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horizontally-opposed
I've been reviewing past discussions on these (links below) off and on, having test fit a 215/60R15 Pirelli P6000 on a 911R wheel into both rear fenders of my narrow-body 914. It seems doable, but it's going to take some massaging on the outer fender, custom spacers, and—maybe—narrowed trailing arms. Which got me to thinking about the current state of the 914 trailing arm, which is the same it's been since 1970.

Basically, those heavy, non-adjustable steel trailing arms are one of the very few things on the 914 that hasn't been addressed or evolved by the aftermarket.

I'm running PMB-rebuilt trailing arms with PMB-rebuilt calipers, and can redo them again with reinforcements and/or some reshaping, but I wonder how hard would it be to do blade-type trailing arms of similar strength with less weight and/or more adjustment. Could a 911 spring plate, or a triangulated or otherwise reinforced version of it, be adapted? Looking at the basic design of the 914 arm, it doesn't look all that complicated, but I'm no engineer.

EDIT: Possible use of a machined 986 wheel carrier, an aluminum casting by Brembo that incorporates the 986 e-brake and 986 four-piston caliper mounts, comes up later—a very interesting idea from @Chris914n6, particularly as the castings are available for $100-200ea used or new from Porsche. Bolting that carrier to a new steel trailing arm with a lower damper mount seems viable to me, but here to learn.

The custom work to narrow factory 914 trailing arms looks extensive, but has been done by both @914timo and @sixnotfour as well as, it looks like, Rich Johnson. I could see doing it in the process of moving to 911 e-brakes and 986 2.5 brakes, maybe, but I wonder if a group buy might attract a 914 vendor we all want to support?

Relevant threads:

http://www.914world.com/bbs2/index.php?sho...p;#entry1247827

http://www.914world.com/bbs2/index.php?sho...ailing&st=0

http://www.914world.com/bbs2/index.php?sho...238144&st=0

http://www.914world.com/bbs2/index.php?sho...234391&st=0
Mark Henry
I'll look through the links later, interesting.

One issue is the 215/60R15 tires, your choice beyond sucks, best tire you can do is a very short list of all season and winter tires.

Now do this and fit in 17x7" rims and you might have a winner.
horizontally-opposed
Test fit of 215/60R15 in stock rear fenders:
horizontally-opposed
And on a 911R wheel with stacked washers to optimize spacing.

The wheel/tire fit into both fenders so that the car could be safely lowered, but the fenders would need a bit of rolling/pull before the wheels were spaced further out. It's been done with regular 15x7 Fuchs and Cookie Cutters, but the 911R wheel will provide better offset.
horizontally-opposed
Interference!
eeyore
If you want to go off into the weeds for ideas, look at the rear suspension bits for the Audi/VW MQB platform (e.g. Tiguan 4motion, Q3 or Q5?)

They have a blade type rear suspension with transverse links for camber and toe control.
gms
I have always thought it would be great if someone made trailing arms out of cast aluminum like the later 911s
Chris914n6
I have a 225/50-16 stuffed in the rear. I ran out of room between the sheet metal way before the arm could be an issue.

2nd thing... why would I ever want an oversized 215/60-15 with huge sidewall bulge?
horizontally-opposed
QUOTE(gms @ Jan 26 2021, 02:34 PM) *

I have always thought it would be great if someone made trailing arms out of cast aluminum like the later 911s


This. Or carbon fiber if it makes sense, at this point.

QUOTE(Chris914n6 @ Jan 26 2021, 02:41 PM) *

I have a 225/50-16 stuffed in the rear. I ran out of room between the sheet metal way before the arm could be an issue.

2nd thing... why would I ever want an oversized 215/60-15 with huge sidewall bulge?


On factory 16x7s, right? I have seen it done a few times. I'm more interested in getting the tire inboard on a 911R-style wheel, as I want to stay with 15s and the "narrow body" look.

185/70R15 or 195/65R15 front and 215/60R15 are the correct spec with the right overall diameter for a lot of Porsches—from the 1973 911 Carrera RS through Carrera 3.2s and 944s of the late 1980s. Good setup, several performance tires available, and period correct looks. There's a lot to like about factory tire sizes—and now there are some good wheel choices as well, ready to mount for similar or less money than "normal" Fuchs that need to be restored and a lot less than previously unobtanium 911R wheels.

https://tremotorsports.com/exterior/fuch-st...deep-6-7-wheels
SirAndy
From the looks of it, even if you did use slimmer trailing arms, you don't have *any* space left for the tire to move as the suspension loads.

Every little bump in the road will make the inside of the tire rub. What you show in the pic below is not nearly enough clearance to deal with camber changes as the suspension moves.

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horizontally-opposed
QUOTE(SirAndy @ Jan 26 2021, 02:48 PM) *

From the looks of it, even if you did use slimmer trailing arms, you don't have *any* space left for the tire to move as the suspension loads.


Precisely my point above re: dynamic clearance. I know a 215 or 225 can be snuck into the fender, though. Plenty of people have done it.

Tire is going to have to come out, which means more spacer. That may alleviate the need for a relocated brake line or a narrowed trailing arm somewhat, but I am not sure that it would help enough given 914timo's experiences.

914forme
I ran 225 on 15s never 16s, spacers where used for inner clearance. Fenders ended up being mildly flared to do it.

LOL these where Hoosiers A7 so they tend to run a bit wider than the numbers on the sidewalls. Rule of thumb in NASA racing is the Hoosier run 20 over the number posted on the sidewall.

Would prefer to do a carbon fiber arms if redesigning an arm, but lets be real, if going to all that, change it from a trailing arm to something a bit better. Not going to say what the would be but for me I have had my dream setup for a long time.

Then I hit the easy button and bought a Boxster. Now I can run 285 out back, and 255s up front. Problems solved. All that is missing is an LSD and more power just like the 914, one of two of these items will be solved shortly. The other will be solved when the right car pops up on coparts shades.gif
mskala
I'm not sure of your goal, here. Is your desire wide tires? Or
60-series tires (balloons)? Or do you really just want 911R rims?
Or do you love fabricating stuff just to say you did it?

So my comments may or may not be helpful. On my -6, I can
run Hoosier A7 205/45/16 on a 7.5" rim. It does not have flares.
The fender lips were flattened and pulled on a bit, and I am
using about 2 degrees negative camber. They have rubbed the
paint off the inner fender over time. I needed to get the spacers
right, and I have them in 3mm increments.

Before I had hoosiers, I video taped my suspension with other
racy tires, and like Andy said, they move a lot under side loads.
If you have good paint you don't want to destroy, give yourself
1/2" on each side. The 914 is great if you have plastic bushings,
since you can disconnect the shock and move the arm up and
down as far as you want to check the static fit.

In my opinion, you will never be able to fit the tires you're showing
without fender work.

I don't understand what the trailing arm width has to do with
fitting tires, the stock ones will accept a wide wheel in the location
it needs to be.

Rather than fabricate arms for no reason, you can just get some
Fuchs and have them widened on the inside, and use appropriate
spacers. That has to be cheaper and easier than custom arms,
and probably nobody will will be able to tell.

mepstein
Pete - I don't think you will get wider tires on the car without messing with your fenders in some fashion. In addition, the higher aspect ratio tires will always move more side to side and need more room to keep them off the fender. Ive seen a couple 914's and 911's burn through the paint on the fender from tires that "just fit".
horizontally-opposed
^ Several people have narrowed the trailing arms. I've had 205/60s and 205/55s in my stock rear fenders over the years with no issue. Others have gone up to 225/50R16 or 225/50R15 in stock fenders "with a bit of work." That work has varied. There are a number of threads.

215/60s are hardly "balloons," as that's the factory aspect ratio/overall diameter for all 15-inch applications. I happen to love the bulging sidewall with 215/60—but it's a matter of taste as 50- or 45-series rubber looks incorrect on these old cars. Again, a matter of taste/preference.

Agree on dynamic clearance, and well aware of that phenomenon, but feel that can be dealt with on the fender side and a wheel spacer. Trailing arm/brake line clearance was a bigger problem when I did the test fit, so it would be good to address it.

Trailing arm question came after reviewing threads of others' experiences in sneaking more rubber into a narrow body car. Many of them narrowed the trailing arms, particularly with wheels that tuck the tire inward with the 911R offset (my preference), which I believe is preferable as an offset to a standard 15x7 Fuchs—both technically and visually.

Finally, trailing arm question is prompted by the idea of paying for a second round of work on my trailing arms. By the time you narrow a pair, adapt 911 e-brakes, add new bearings, etc, one begins to wonder if you want the same old boat anchor—and if you're alone. Curious if Dave Darling remembers who built/offered/canceled the blade type arms with camber/toe adjustment at the rear of the arms. Unsprung weight is always nice to get rid of, too—and I know several people building 914s that might be able to justify a better option for the rear arms. Perhaps the economics/demand is different now than it was then—but the hours involved in reworking old trailing arms may help offset the cost of something better.

The right design should have merit regardless of what wheels are used. If it provides more tire clearance on the inside, well, that's a boon.
horizontally-opposed
QUOTE(mepstein @ Jan 26 2021, 06:00 PM) *

Pete - I don't think you will get wider tires on the car without messing with your fenders in some fashion. In addition, the higher aspect ratio tires will always move more side to side and need more room to keep them off the fender. Ive seen a couple 914's and 911's burn through the paint on the fender from tires that "just fit".


^ Totally agree. This project, if it happens, will require a mix of things to sneak them in. But it's been done before.
Chris914n6
QUOTE

QUOTE(Chris914n6 @ Jan 26 2021, 02:41 PM) *

I have a 225/50-16 stuffed in the rear. I ran out of room between the sheet metal way before the arm could be an issue.

2nd thing... why would I ever want an oversized 215/60-15 with huge sidewall bulge?


On factory 16x7s, right? I have seen it done a few times. I'm more interested in getting the tire inboard on a 911R-style wheel, as I want to stay with 15s and the "narrow body" look.

185/70R15 or 195/65R15 front and 215/60R15 are the correct spec with the right overall diameter for a lot of Porsches—from the 1973 911 Carrera RS through Carrera 3.2s and 944s of the late 1980s. Good setup, several performance tires available, and period correct looks. There's a lot to like about factory tire sizes—and now there are some good wheel choices as well, ready to mount for similar or less money than "normal" Fuchs that need to be restored and a lot less than previously unobtanium 911R wheels.

https://tremotorsports.com/exterior/fuch-st...deep-6-7-wheels

Stock wheels & tires, for a Boxster biggrin.gif
With spacers I think I ended up at Fuchs 911 offset and a bit of camber and rolled the fender.

I think I test fit a 215/60 on a 7x15 cookie from the 944 set I bought. Billowing sidewalls. Might as well call them pillow tires for a sleepy drive laugh.gif

Found it. Silver cookie is a 6". I recall the 7" rubbed or was otherwise not worth using for donuts.

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For comparison wide 205/55 on a 7x16 911 Fuch spec. Basically the same as my Boxsters.
horizontally-opposed
Silver cookie setup looks good to me. chowtime.gif

As for pillows…  biggrin.gif yeah maybe for all-seasons. But 185/70 front & 215/60R15 rear was standard for a 1973 Carrera RS while 195/65 front & 215/60R15 rear is standard for a 911 SC and Carrera 3.2. So that's a pretty attractive "maximum" setup for a narrow-body 914 with 200-250 hp—and Avon CR6ZZ are available in those sizes and were available from Roger Kraus Racing in three compounds last time I bought a set of 185/70s. Pirelli P6000 and CN36 are available in those sizes, too—and the revisions might accept 225/50R15 rears as well, which opens the door to Toyo RA1s and other interesting options if the car ever sees a track again.

It's going to take some work, but others have done it—on both narrow 914s as well as narrow early 911s—and whatever the work…it's a lot less work than GT flares and painting both sides of the car. Figure it can be pulled for now, and perhaps redone to a higher standard with the next paint job. Need to put some more miles and rock chips on this one first. smile.gif

Chris914n6
I have a set of 225/50-15 on Fuchs I've been wanting to trial fit. Will be at least a week before it stops being cold and wet.

Also, I can spin my 225s in 2nd with 200hp, so 215 isn't going to change anything from 205.

So really, that's alot of work for 1/2" just because Porsche did it on the bigger 911 & 944 in the 80s.
mskala
I wasn't trying to judge what you're doing, whatever you want it's great.

Note one other thing; maybe you already know, but a wider wheel makes
the section width of the tire wider also. The 911R 7" rim is 49mm offset
and Fuchs 6" rim is 36mm offset, so the outside of the rim will be in
the same plane when mounted. So there is no benefit to using 911R rims
(if the tire will mount safely, which 225 or less will.)
Racer
its my recollection that the Maxlite 911R wheel is NOT an exact 911R replica. Maxlite is 47mm offset while the original 911R is 49mm offset.. and in this case, 2mm will matter!

We had a 74 911S (stock narrow rear fenders) and ran 911R wheels with 225/50-15 yokohama A008 (1980s here for reference). Despite fender lip rolling (like yours) previously on our 914/6 (to fit a 205/70-14 in period tire combo), that 911R combo just wouldn't fit on our /6 or on my /4. Both cars would require a slight pull of the fenders to work (but less pull than a 7x15 et23 wheel). fwiw, on our /6, the 205/70-14 was an extremely close fit, such that a 195/70 became the default tire in the 1970s on that car.

You also need to take into account tire flex / expansion and suspension movement etc under use.. and the harder the use, the greater the movements.

Another question, even if the trailing arm was made thinner, what is the relationship (plane) between the arm and the inner fender well? Does the arm protrude past the inner fender well or sit flush? ie, even if you thin the arm, will the tall tire still hit the inner fender?
Andyrew
My issue has always been rubbing the top of the chassis sheet metal. I've done it many times and have the half moon scars to prove it smile.gif


Not once have I hit the trailing arm, and if the brake line got in the way then it was relocated.

If we didnt have increased camber as the tire went up then the trailing arm might be more of an issue.....

Also I have a fairly well sprung ride (225/275) so I dont have excess travel like a softer car.



I think your looking at the wrong issue here Pete. With the stock chassis 914 owners need to go outwards for larger tires. Not inwards.

(That being said... I have always wanted to build a tube chassis rear that can put a significant amount of tire more inward....)
mepstein
Pete - Just buy this.
914forme
The original Sheridan car had a custom set of rear arms with all the toe and camber settings out on the end of the arm.

Can be seen in the ultimate 914 racer Articles in European car circa 2013
horizontally-opposed
QUOTE(914forme @ Jan 27 2021, 05:11 PM) *

The original Sheridan car had a custom set of rear arms with all the toe and camber settings out on the end of the arm.

Can be seen in the ultimate 914 racer Articles in European car circa 2013


Ah, Roger's car. I wonder if that's the one Dave Darling was thinking about?

Looks like they're pretty trick—as is so much of that car—but that they push the ultra-wide wheels even further out, as one can with the Ultimate 914 bodywork.

horizontally-opposed
Thinking more down this road…though 914 unibody is obviously very different.



sixnotfour
Half way there..
rick 918-S
I totally get the look. 15's with vintage looking tires are so period 914. It really sucks that the tire selection is so limited. I really liked the Yokohama's mounted on my 15X8's with 225/60's and 215/60's vintage cool. I ended up going to 16X8 and 16X9's running 275/50's and 225/50's Yokohama tires until they discontinued the 275's I am down to one tire selection and that will eventually evaporate too.

Question: I don't have a car here at the new house I can examine. Is the trailing arm the first obstacle inboard or is the body sheet metal the first point of contact?

The trailing arms can be modified pretty easily really without going to a flat plate type arm if there is any benefit.
horizontally-opposed
QUOTE(sixnotfour @ Jan 28 2021, 04:33 AM) *

Half way there..


Holy moly…
horizontally-opposed
QUOTE(rick 918-S @ Jan 28 2021, 05:39 AM) *

I totally get the look. 15's with vintage looking tires are so period 914. It really sucks that the tire selection is so limited. I really liked the Yokohama's mounted on my 15X8's with 225/60's and 215/60's vintage cool. I ended up going to 16X8 and 16X9's running 275/50's and 225/50's Yokohama tires until they discontinued the 275's I am down to one tire selection and that will eventually evaporate too.


Your car looked fantastic on the 15s—I hope you kept them? I am hearing more and more good things about the Radial T/A, which appears to be available in 215/60 and 225/60. I wrote them off as Trans-Am tires but some Porsche guys are running them out here and say they feel good. They were cheap for a long time, then went up considerably (still much cheaper than Avons or a lot of other tires). My guess is that Michelin, which owns BFG, may have updated the technology behind them or at least the compounds. May be worth a shot, with black letters out?

And yes 16 choices are thin on the ground these days but better than they were a couple of years ago. Period P7s and a good Yokohama are out now, both of which would look great on a 914 with M471 flares, though they're 225/50 and 245/45. The fact that 15s went to near zero choices, sending many to 16s, suggests maybe the 16s will come around again too. I know people who buy and bag tires for old cars when they come available, as they're loathe to settle for all-seasons or worse, no tires at all—a big part of why I'm liking factory tire sizes. They not only look right, they're likely to be available in at least 1-2 sizes.

QUOTE(rick 918-S @ Jan 28 2021, 05:39 AM) *


Question: I don't have a car here at the new house I can examine. Is the trailing arm the first obstacle inboard or is the body sheet metal the first point of contact?

The trailing arms can be modified pretty easily really without going to a flat plate type arm if there is any benefit.


First point of contact is brake line & trailing arm—there's room at the inner fender, to my surprise with a 215, though not enough for the tire to move around under load. So pulling the outer fender and adding more spacer will help the inner fender more than the brake line & arm. Right solution probably needs to address both.

Sounds like I might be shopping for a pair of good trailing arms…
Montreal914
A few years back, planning on my 5 lugs upgrade, I had a nice set of 15 x 6 Fuchs. After reading that the tire selection is greater with the 16", I sold them and got a set of 16 x 6. headbang.gif

I am currently preparing my narrow body car for paint and will eventually reassemble it with the 5 lugs.

I am puzzled as to what summer tire selection there actually is in the 16" sad.gif . It feels like the selection is greater in the 15", or am I missing something... confused24.gif

Being in SoCal, I am looking at summer tires, but don't want too much of a modern look. I understand that by switching to 16, I walked away from the proper era look headbang.gif

Sorry to jump in the OP's thread, but I know Pete is thoroughly investigating the tire file... I read one of your post talking about the Michelin Pilot Sport AS3 205/55/16. I am not sure if this model is still available though...

Interesting topic! smile.gif popcorn[1].gif
horizontally-opposed
QUOTE(Montreal914 @ Jan 28 2021, 08:25 AM) *

A few years back, planning on my 5 lugs upgrade, I had a nice set of 15 x 6 Fuchs. After reading that the tire selection is greater with the 16", I sold them and got a set of 16 x 6. headbang.gif

I am currently preparing my narrow body car for paint and will eventually reassemble it with the 5 lugs.

I am puzzled as to what summer tire selection there actually is in the 16" sad.gif . It feels like the selection is greater in the 15", or am I missing something... confused24.gif

Being in SoCal, I am looking at summer tires, but don't want too much of a modern look. I understand that by switching to 16, I walked away from the proper era look headbang.gif

Sorry to jump in the OP's thread, but I know Pete is thoroughly investigating the tire file... I read one of your post talking about the Michelin Pilot Sport AS3 205/55/16. I am not sure if this model is still available though...

Interesting topic! smile.gif popcorn[1].gif


16x6 allows for some GREAT tires—from (at last check) the Pilot Sport AS3, which has a simple sidewall and an "old enough" looking tread pattern and more than enough performance and feel for me on the street, to some pretty serious R-compound tires for autocross and track use. Last I checked, not only Toyo RA1 but also Michelin Cups and some others.

The good news with 205/55R16 is it was original fit for Porsches on 16-inch alloy wheels from 1975~ through 2004 (last of the 986s on 16s) as well as a ton of other performance cars built in big numbers, such as the Subaru WRX. The bad news is sneaking them into the rear fenders. I had no problems with 205/60R15 other than a bit of rubbing on the inside, so you might get them in. Some 914s seem to have less clearance than others.

You may also have a bit of interference up front depending on where your wheels sit in the fenders (I use spacers up there, and 185/70s can occasionally just barely catch my LE-style spoiler with the right amount of steering lock and suspension compression, such as on the way into a certain kind of driveway…though it's ultra rare and I've seen zero damage). But if you sort them, as many have, 205/55R16 is a wonderful size for a narrow body 914 and probably the ultimate performance setup without resorting to much in the way of trickery.

Looks like the AS3s are available in H-rated or V-rated for $135-140ea, but may be on closeout? But whatever, I doubt availability or selection will be a problem with 205/55R16. 225/50R16 may be a bit more of an issue, and 245/45R16 has already been an issue (being down to track tires or Fuzion, take your pick) but there are some very good 245/45 options out there again.
Montreal914
Thank you for this very valuable information smilie_pokal.gif
I will look for some AS3 thumb3d.gif I do have an LE replica valence, and also have a set of thin spacers (6-7mm?) off of a 68 911 that I might use in the front to fill up. I will definitely keep in mind all of the clearance issues you have pointed out. I hope the rear wont be an issue. sad.gif Didn't think it would be... You are now making me wonder if I should try the rear fit before having the car painted, but that would mean installing the new 5 lugs trailing arms and... Many things to think about, Thank you!!! smile.gif
horizontally-opposed
^ You are welcome, but @sixnotfour is probably our resident king of sneaking 205/55R16s into stock or stock-ish rear fenders.

I just wanted to get a conversation about rethinking the 914's trailing arms going.

After some more thought, I wonder if I can't rope @Optimusglen in, as some of the thinking stems back to the dreamy "GT" build we commissioned him to render for 000 (below) and might even tie into something else he's working on.

If a North American wheel supplier can create custom billet 20x12-inch wheels that exactly match Porsche AG concept car wheels for $1250~/wheel, I have to suspect two pieces of billet aluminum to accept stock, poly, or needle bearings up front and a 911 e-brake, wheel bearing, and a caliper at the back connected by a "blade" or two of carbon fiber might not be so crazy? It would be interesting to compare prices for the above against making jigs to narrow 50yo steel arms, adapting 911 e-brakes, repainting, and rebushing a set of stock trailing arms—which would still be boat anchors. Lightweight arms might save 20-30~ pounds in unsprung weight. Pair that with a lightweight battery, and it could add up to half~ the weight gain of a six conversion in roughly the same part of the car. Not gonna be cheap, but look what folks spend on bodywork, paint, wheels, lightweighting (!), etc.
mepstein
Pete - Have you weighed a 914 trailing arm. They look heavy but really not that bad. I don't have one in front of me but I'm guessing a bare one at 12-15lbs.
horizontally-opposed
QUOTE(mepstein @ Jan 28 2021, 12:45 PM) *

Pete - Have you weighed a 914 trailing arm. They look heavy but really not that bad. I don't have one in front of me but I'm guessing a bare one at 12-15lbs.


I've handled three pairs of them over the years, with and without other parts on them, and they seemed like a heavy, strong, and inexpensive part for a mass-produced car.

Kinda like early 911/912/911 steel crossmembers, before PAG moved to aluminum.

I'd be curious to know their weight without bearings, etc.—as that would be the relevant comparison. In the old days, I could head down to EASY and very likely weigh one. Those days are gone, sadly.
ClayPerrine
Just put this under the back of your 914. Better suspension design, already has a parking brake and big vented rotors.

IPB Image
horizontally-opposed
QUOTE(ClayPerrine @ Jan 28 2021, 01:35 PM) *

Just put this under the back of your 914. Better suspension design, already has a parking brake and big vented rotors.

IPB Image


^ Ha.

Guessing this requires cutting the 914's unibody up, isn't compatible with 914's track width, wouldn't fit under standard 914 fenders, and would ultimately be heavier and more expensive than custom trailing arms let alone a small run of lightweight arms…
mepstein
QUOTE(horizontally-opposed @ Jan 28 2021, 04:28 PM) *

QUOTE(mepstein @ Jan 28 2021, 12:45 PM) *

Pete - Have you weighed a 914 trailing arm. They look heavy but really not that bad. I don't have one in front of me but I'm guessing a bare one at 12-15lbs.


I've handled three pairs of them over the years, with and without other parts on them, and they seemed like a heavy, strong, and inexpensive part for a mass-produced car.

Kinda like early 911/912/911 steel crossmembers, before PAG moved to aluminum.

I'd be curious to know their weight without bearings, etc.—as that would be the relevant comparison. In the old days, I could head down to EASY and very likely weigh one. Those days are gone, sadly.

I'll do it tomorrow if nobody beats me to it.
rick 918-S
If I had my new shop set up I would build a gig and narrow a couple. One of you guys should take this on for Pete. Couldn't take but a couple days of messing around to make a couple.
Eric_Shea
We could play with it if you want...
mskala
7.5"x16 ET38 wheels, minimal spacers different on each side. Normal trailing arms.
Hoosier 205/45/16 which of course runs wider than numbers would suggest.
Does not hit the brake line or arm. Fenders were yanked a bit and folded. Inner
wheel well rubs first, before you would rub brake line or trailing arm.

Click to view attachment
horizontally-opposed
QUOTE(rick 918-S @ Jan 28 2021, 02:30 PM) *

If I had my new shop set up I would build a gig and narrow a couple. One of you guys should take this on for Pete. Couldn't take but a couple days of messing around to make a couple.


Thanks, Rick—but I am actually interested in something for more than me.

Our 914s have always lived in the shadow of the 911 when it comes to suspension upgrades, being "lucky" to benefit from parts developed for the front of the 911 and even luckier if a matching rear damper/spring was available. I get the idea that there wasn't enough market to justify the developments we've seen for 911s in years past, especially when 914s were $5000-30,000 cars, but I have to wonder if there isn't now?

How many people have made jigs to narrow two trailing arms (I've found several independent jobs in my research) and/or slice off the wheel carrier to weld up a 911 e-brake to gain access to better/lighter calipers? And you're still dealing with a 50yo arm that might need to be repainted, etc. And maybe reinforced, too—though there are two schools on that. How much does all that labor add up to?

Might be cool nice to see something developed that addresses all that, takes any of the three available bushing types up front, accepts a 911 e-brake, can accept different calipers via adapters (914, 930, 986), and maybe offers some adjustment with 2-3 mounting points for the rear damper. Won't be cheap, but people are spending real money on 914s these days. I know of someone who might be willing to fund such a thing if it's done to a high level—and that would leave a cool product on the market. Or maybe we can figure out a group buy. I've been cooking through another idea that might drop serious weight off the back of the 914, and might not be insane in lieu of what some are spending or will eventually spend in this area of the car. I know an F1 contractor who might be cajoled into helping with the billet aluminum (or?) sections, but we also have some very smart cats here.

Yes, I'm definitely thinking out loud—and taking some hits for it—but that's all good.

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QUOTE(mskala @ Jan 28 2021, 03:01 PM) *

7.5"x16 ET38 wheels, minimal spacers different on each side. Normal trailing arms.
Hoosier 205/45/16 which of course runs wider than numbers would suggest.
Does not hit the brake line or arm. Fenders were yanked a bit and folded. Inner
wheel well rubs first, before you would rub brake line or trailing arm.

Click to view attachment



Thanks for this, and very cool to see. I've seen people sneak 16x7 Fuchs in (both 951 and maybe 911 too?), but not these—as they appear to have a bit of lip on them. 205/45R16 definitely seems to help, too. @sixnotfour is running custom 16x7.5 Fuchs also, I think, but they're flat-faced with the added width on the back iirc. Like a 16-inch 911R wheel.

As you note, actual tire widths ≠ tire sizes. When I ran 205/60R15 A-008Rs, I had the same point of interference as you and no interference at the brake line/trailing arm. I went on to drop down to 205/55R15 BFGs and, later, Yokos, and had no issues. 185/70 and 195/65 have all been fine, but no surprise there. Test fit with the 215/60R15 Pirelli P6000 shows brake line clearance is a bigger problem than inner fender clearance—so pulling the fender and spacing the wheel further out will help the inner fender more than the brake line, and I'd love to minimize that fender pull…


QUOTE(Eric_Shea @ Jan 28 2021, 02:35 PM) *

We could play with it if you want...


Was hoping you might chime in, as one of very few logical vendors for trick 914 trailing arms. sunglasses.gif

Would be great to compare notes and do some thinking…
mskala
QUOTE(horizontally-opposed @ Jan 28 2021, 07:15 PM) *

Thanks for this, and very cool to see. I've seen people sneak 16x7 Fuchs in (both 951 and maybe 911 too?), but not these—as they appear to have a bit of lip on them. 205/45R16 definitely seems to help, too. @sixnotfour is running custom 16x7.5 Fuchs also, I think, but they're flat-faced with the added width on the back iirc. Like a 16-inch 911R wheel.

As you note, actual tire widths ≠ tire sizes. When I ran 205/60R15 A-008Rs, I had the same point of interference as you and no interference at the brake line/trailing arm. I went on to drop down to 205/55R15 BFGs and, later, Yokos, and had no issues. 185/70 and 195/65 have all been fine, but no surprise there. Test fit with the 215/60R15 Pirelli P6000 shows brake line clearance is a bigger problem than inner fender clearance—so pulling the fender and spacing the wheel further out will help the inner fender more than the brake line, and I'd love to minimize that fender pull…


Slight error with the pic, it was taken earlier with Kumho V710 215/40/16, which I
measured as 8.5" section width. Hoosier was wider than this.
mepstein
185/70 front & 215/60R15 rear was standard for a 1973 Carrera RS

So one of Porsche's most iconic cars made due with relatively narrow rubber and a 914 could be said to be lighter and better balanced.

Is it just about getting the wider tire on the car. Better handling. Both?

One thing that was suggested to me to improve the ride and handling on our cars was better custom valved shocks. The most common shock upgrade to Bilsteins just uses a 30+ year old design.

We all just tend to throw a lot of "upgraded part" on our cars without really testing how they work together, sometimes assuming a stiffer ride will be a high performance ride.
horizontally-opposed
QUOTE(mepstein @ Jan 28 2021, 05:33 PM) *

185/70 front & 215/60R15 rear was standard for a 1973 Carrera RS

So one of Porsche's most iconic cars made due with relatively narrow rubber and a 914 could be said to be lighter and better balanced.

Is it just about getting the wider tire on the car. Better handling. Both?

One thing that was suggested to me to improve the ride and handling on our cars was better custom valved shocks. The most common shock upgrade to Bilsteins just uses a 30+ year old design.

We all just tend to throw a lot of "upgraded part" on our cars without really testing how they work together, sometimes assuming a stiffer ride will be a high performance ride.


We're on the same wavelength, and agree with much of the above—but would go further, and less far. smile.gif

I've been testing factory and aftermarket Porsches on road and track since 1997. Long ago lost count of how many cars, track days, and road tests. Along the way, the cars that hit the sweet spot and were "soul connected" were the ones that stood out. They were often less is more, such as a 986 2.5 that was just plain more fun to drive than a 993 Turbo. Or the 987.2 Boxster Spyder, which was far more than the sum of its parts—and probably quicker over the road in the hands of more drivers than a contemporary GT3. And, dare I say it, more fun despite a merely wonderful engine instead of that insane Mezger.

There are a lot of other examples, but the 914 stands tall in this regard—and that goes for virtually any good 914.

The standouts from the Porsche aftermarket are even fewer and further between. Most go for more more more, and the experience isn't any better. And, I'd argue, the driver often ends up less confident, extracts less out of the car, and has less fun. Which is perhaps what you're getting at. I can probably count on 2-3 hands the number of truly brilliant aftermarket Porsches I've tried—they've been rare, and sometimes come from unexpected shops or individuals. One line usually tied them together: Those who carried out the mods were methodical, planned their ideas out carefully, and saw everything as a system. Again, what I think you're getting at.

When it comes to our 914s, a lot of people go for big engines, big brakes, and 16- or 17-inch rubber with 205-225 (or larger…) front tires and 225-265 (or larger…) rear tires. And some 914 hot rods do benefit from that despite relatively modest weight gains vs much less modest power gains. Others end up fast but distinctly un-fun or even scary to drive.

In terms of power, my 914 is making a modest 169 hp at the wheels, so maybe 190-200 hp at the flywheel (insert favorite "conversion/guestimation" here). Target achieved. The 1973 RS 2.7 was rated at 210 hp, and wasn't all that much heavier unless it was a full-boat RST. (One thing to remember re: 914 tire sizes: Wider road/consumer tires weren't widely available on Porsches before the RS 2.7, and were pretty rare in general. Up to 1973, a 185/70R15 was a wider performance tire, and something of a gold standard. Then the 215/60 arrived—and Porsche staggered the tire sizes on a lot of their cars, including even the most modest 2.5-liter early Boxsters.) Porsche used that same 185/215 or 195/215 wheel/tire package on 911s from the 260-hp early 930 through to the 230~ hp 1988 911—in other words, a wide variety of 911s with 180-260 hp and weights both below and above the 914. 16s with wider tires were available as an option or standard on some models (Turbo 3.3, SC, Carrera, SC/RS, Turbo Look, 1989 Carrera, etc). I'd say the 185/215 and later 195/215 has breadth, and we know that tire package met Weissach's performance standards. And the right tires of today in those sizes are better than tires of the same size back then. Much better.

My humble narrow-body 914 drove really well with 185-205 tires at all four corners when it had 80hp. I didn't need the 205s due to power, to be sure, but the chassis sure could put 205s to good use at high and low speeds. Perhaps more importantly, I just liked the car that way.

Fwiw, I was talked into Bilstein HDs by a number of people I respect during my last suspension rebuild. About the only thing we got right was sticking with rubber suspension bushings and the same spring rates. I vastly preferred my previous Koni reds to the HDs, and see no reason to reinvent the 914's torsion bar/coil-over concept or move to exotic and/or remote-reservoir dampers. I might convert my Koni reds to double adjustable, but I might not. Zero desire to go to higher spring rate up front, and will likely keep my fairly soft rear springs. Might go up 20-40lb. We'll see. There are other upgrades that are pretty interesting—such as Tangerine's strut top mount for lowered cars (been eyeing that one), raised spindles (should have done that last time), better bump-steer solutions, etc. Little stuff that can make a big difference. There is some big stuff out there, too, such as Elephant or ERP's A-arm replacements, but I am not sure these are right for a street car—especially at the front end.

On the other hand, trailing arms in modern materials and lighter brakes might offer a chance at serious weight loss (total, unsprung, and rotational). Steel trailing arms were cheap and strong. Heavy, too. Steel brake calipers and one-piece rear rotors were, as well. Better rear arms, alloy calipers, and maybe even two-piece rear rotors—if the right disc can be sourced and the e-brake can be figured out—might drop significant weight. No, it won't be cheap, but I suspect an Avon 215/60R15 on a 911R replica wheel on a lightweight arm with a lighter brake setup—along with a well thought-out front end—might end up less expensive than adding M471 or custom flares, the usual suspension/brake upgrades, and repainting the car. And for those of us who like the narrow-body look…
Chris914n6
~21.5 lbs as seen. Scale might not be 100% accurate.

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mepstein
QUOTE(Chris914n6 @ Jan 29 2021, 03:16 AM) *

~21.5 lbs as seen. Scale might not be 100% accurate.

IPB Image

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So without the hub, bearing, bracket and shaft, fifteen-ish, maybe?
horizontally-opposed
Thanks Chris!

A little lighter than I expected, but they certainly aren't light. There may be 30 to 50+ pounds in unsprung/rotational mass to be shed between the 914's steel arms, steel calipers, and one-piece steel rotors x2 while adding a number of technical upsides.

Question is how light they can be made, and for how much.

Next question is what the $ might look vs against narrowed/reinforced/e-braked/rebuilt arms. Or flares + paint. And then how many orders would it take for a vendor to step up? The concept is easy. The execution is well outside my ability, and likely prohibitive as a one-off, but it would be a great piece to have on the shelf while assembling parts for the next suspension redo…
horizontally-opposed
QUOTE(mepstein @ Jan 29 2021, 05:40 AM) *

QUOTE(Chris914n6 @ Jan 29 2021, 03:16 AM) *

~21.5 lbs as seen. Scale might not be 100% accurate.

IPB Image

IPB Image

So without the hub, bearing, bracket and shaft, fifteen-ish, maybe?


Not much to be done with the wheel bearing, but the shaft and hub might be a place to apply better materials. Maybe also set up for four or five lug wheels.

Anyway, suspect your guess is within a pound or two.
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