Modern trailing arms for the 914?, 986 carriers/calipers/e-brake, more adjustability, more tire? Options

[Chris914n6]

I did the research on putting a Cayman rear suspension under a 914.

The track is about 6 inches wider. So you get 3 inches on each side. A different offset wheel (A Cayman wheel) would probably fit with no spacers under a narrow bodied car. For a flared car, just use a wheel with the correct offset.
Clay

Cayman/Boxster/996 wheels are only offset an additional inch, none of that will work as you think.

You need to narrow the subframe, which likely means fabbing a new steel frame which holds the susp arms, which would be built to fit the 914.

[horizontally-opposed]

You forgot the underscore in my user name, so I didn't get the notification.

Anyway, I do not remember who made the arms. I think it was on Porschephiles back in the 90s, and what I remember is:
- They made tubular trailing arms, not blade-style
- Adjustment was out at the wheel end
- They didn't sell, and were abandoned
- It was done at least a few years before I heard about them, so possibly in the 80s

That's it. Sorry I don't have any more information.


I'd be worried about the strength of blade-style arms. There's a lot of torsion going through the 914 arm, and a flat piece of metal will bend a lot in torsion. Multiple blades can deal with that to some extent, or a blade to carry the loads in one direction with an I-beam or a box to carry the rest. (Note that the 911 spring plate for the most part only carries the torsion bar loads. The cast arm carries the twisting loads and such.)

Sounds like this is a lot of work for little benefit, frankly.

--DD

Sorry for forgetting the underscore, Dave!

Thanks for sharing what you remember. I had the sense the trailing arm project you mentioned was more recent and failed to find buyers. I suspect the market is quite different 30-40 years later—consider the number of six-figure 914 projects in recent years, or upgrades to four-piston calipers and/or 911-style e-brakes. This thread already has 3,100 views, so it would seem there's at least some interest.

As to work and cost, a pair of brand new arms that allow use of factory parts that didn't exist in the 1980s or early 1990s might end up less expensive than restoring and modifying 50yo trailing arms. People are already doing a lot of work for little benefit, building trailing arm jigs to reinforce, add 911 e-brakes, change the caliper mounts, and/or narrow 50yo trailing arms. Sounds like there are quite a few of those jigs out there, with most presumably built for just two arms. One friend suggests "about a day" to build the jigs, and one has to hope the arms used to build them aren't bent 45-50 years later. Going rate for the work above sounds like $800-2400, without making jigs.

So the critical question seems to be: Can a simple multi-blade, blade/rod, or even partially boxed arm that works with existing 914 bushings up front and mounts a modified or unmodified 986 wheel carrier at the back be engineered? That's well past my pay grade, but solving the torsional loads seems do-able. The result would leave 914 owners with long-term parts availability and choices (stock rubber, poly, or needle bearings, not to mention used or new 986 brakes, wheel bearings, e-brake parts, etc). Added clearance for a 215 or 225 rear tire with less pulling on the outer fender would be a nice upside for those who don't want M471 flares or don't want to spend $5,000-20,000 extra to put M471 flares on a "mild" six conversion with ~200 hp. Multiple lower mounting points for the rear damper might be interesting, as fine adjustment for ride height as seen on Rennline's steel 911 spring plates for $250/pair would be.

And even if steel is the obvious choice for new trailing arms due to cost, killing any weight advantage, lighter 986 calipers and an e-brake design that makes use of the interior of the brake "hat" would offer significant advantages. A two-piece rotor with an aluminum hat would take that savings even further.

[ClayPerrine]

Pete...

Modding the trailing arms for wider tires won't help when the trailing arm is at the same relative location as the inner fender wall.


Clay

[horizontally-opposed]

Pete...

Modding the trailing arms for wider tires won't help when the trailing arm is at the same relative location as the inner fender wall.


Clay

Maybe. When I did the test fit with a 215/60 on a 7R, the brake line was the only point of interference. Relocating the hard line alone might would help, particularly as the outer fender is pulled and the 15x7R is spaced out (and the less the better), but I got the sense the arm will also need to be narrowed at least a few millimeters so the tire can move around—and likely even more so with a 225/50.

While the ability to more easily sneak a 215 or 225 into stock-ish rear fenders is an upside that may or may not justify a new trailing arm for some, the far more compelling upside is no longer having to fuse 911 wheel carriers/e-brakes/caliper mounts/etc to 50yo trailing arms. I've seen that go wrong, to the point it had to be done over, even with a good shop doing the work. New arms + 986 carriers may be cheaper, as well. Any further advantages—adjustability, weight, off-the-shelf availability, etc—would be just that.

I can see a market for a good alternative to modded/restored trailing arms, no matter what sort of 914 hot rod someone is building—mild or wild. I have a tougher time seeing much a market for a setup that requires new pickup points, cutting the chassis, welding, etc. or anything else that isn't reversible.

[Chris914n6]

FYI
Boxsters use 914 rear bearings, thus the compatibility I inferenced.
911 e-brakes bolt on with a welded on tab to secure the shoes. Not complicated.

The wheel well is like 10" deep. If you are hitting arm before inner you have a camber issue.

I think you are focused on a problem only you have because you want to run 80s 911/944 spec (and 80s tech) balloon tires.
15" tires are what was made at the time. 16s were new and pricey. Today 18s are stock on just about everything.

[horizontally-opposed]

FYI
Boxsters use 914 rear bearings, thus the compatibility I inferenced.
911 e-brakes bolt on with a welded on tab to secure the shoes. Not complicated.

The wheel well is like 10" deep. If you are hitting arm before inner you have a camber issue.

Camber is within spec; it was set when the PMB arms went in and more recently checked again.

The section width for Avon and Pirelli 215/60R15 tires is listed at 8.7-8.8", while a 225/50R16 Michelin Pilot Sport 4S is listed at 9", so I'd be thrilled if there was something like 10" to play with. My test fit suggested it's closer to 9".

Adding 911 e-brakes doesn't concern me, but I've seen complications with adding tabs for 911 calipers that led to brake squeal. The remedy was a do-over. Having watched a friend deal with that after a good shop got it wrong, that is a consideration. 986 wheel carriers would eliminate that issue and make 986 four-piston Brembo calipers and drum-type parking brakes a bolt-on upgrade for a fraction of the price of 911 brakes plus 911 e-brakes, spot calipers, or RSR clamps. And unlike most caliper upgrades for the 914, which are 911 or 930 parts, 986 f/r calipers were sized and balanced for a mid-engined car. It's an idea worth exploring imo.

I think you are focused on a problem only you have because you want to run 80s 911/944 spec (and 80s tech) balloon tires.

(IMG:style_emoticons/default/unsure.gif)

215/60R15
Avon CR6ZZ (vintage race/road rally available in three compounds)
Pirelli P6000 (N-spec summer)
Pirelli CN36 (N-spec w/period looks & modern technology)

215/55R15
Michelin TB 15 VHC Racing Tyre (Dry / Wet, road legal)

225/50R15
Pirelli P-Zero Trofeo R (R compound/summer)
Pirelli P Zero Asimmetrico (summer performance)
Pirelli Cinturato P7 N4 (period correct summer in modern construction/compound)
Toyo RA1 (R-compound track-day tire, retro looks)
Toyo R888R (R-compound track-day tire)
Yokohama Advan A052 (Extreme Performance Summer)

225/50R16
Michelin Pilot Sport 4 (Ultra-High Performance summer, O.E. 991/992)
Michelin Pilot Sport A/S (Ultra high-performance All-Season)
Pirelli Cinturato P7 N4 (High Performance Summer)
Pirelli P-Zero Trofeo (ultra high performance Summer)
Bridgestone Potenza S007A (Extreme Performance Summer)
Bridgestone Potenza RE-71R (Ultra high performance Summer)
Continental ExtremeContact Sport (Ultra High Performance)
Toyo Proxes RA1 (R compound track day/race tire)
Yokohama Advan Neova AD08 R (ultra-high performance summer)
Yokohama Advan A052 (Extreme Performance Summer)

Many/most of these are at the cutting edge of current tire tech, and some allow staggered sizing with 185, 195, or 205 fronts—and there are other summer tires, all-seasons, and near slicks not listed here.

So this is less about "80s balloon tires" or the idea I'm alone in wanting more tire without big flares—as others have snuck 215s or 225s into narrow 914s to varying degrees of success or failure. This is about charting a path that isn't going it alone and doesn't leave other 914 owners to do so. The keys to minimizing work on the outer fender (and all the ills it brings) appear to be wheel offset (15x7R or custom 16x7~) and inner fender/trailing arm clearance. My goal was to stoke discussion around a sensible, repeatable path to the best tires and brakes that will fit under a narrow 914 with the prospect of long availability for consumables. And maybe a trailing arm that offers benefits to any modified 914, including one with big flares.

"All" that's missing is an arm between the 914's pickup points and a pair of (modified?) 986 carriers. Can such an arm be reasonably engineered? I don't know, but I think it's a fair question to ask in a 914 forum…

[rick 918-S]

Some of us really dig the look of fat vintage rubber. The trick is to stuff it into the wheel wells without having to pull the quarters. Or pulling them just enough to gain clearance. I like the narrow cars. I have a couple in storage that I hope to revive with the retro track day look. KISS. (IMG:style_emoticons/default/biggrin.gif)

[rick 918-S]

Some of us really dig the look of fat vintage rubber. The trick is to stuff it into the wheel wells without having to pull the quarters. Or pulling them just enough to gain clearance. I like the narrow cars. I have a couple in storage that I hope to revive with the retro track day look. KISS. (IMG:style_emoticons/default/biggrin.gif)

[horizontally-opposed]

Some of us really dig the look of fat vintage rubber. The trick is to stuff it into the wheel wells without having to pull the quarters. Or pulling them just enough to gain clearance. I like the narrow cars. I have a couple in storage that I hope to revive with the retro track day look. KISS. (IMG:style_emoticons/default/biggrin.gif)

Yeah, there's the aesthetics too. I ran 205/55R15s for a long time but have come to like the look of period correct enough performance tires on narrow and M471 cars. If space and budget permitted it, I'd probably have one of each, (IMG:style_emoticons/default/wub.gif) but I just have one, so I need to make the best of what I've got.

Chris' snark prompted me to take a fresh look at what's available, and I am actually shocked how many great 15- and 16-inch performance tires are available in 215 and 225 widths right now. Things have really changed in this regard.

[live free & drive]

You can see the tire rubbing on the inner wheelhouse in the pic below, but it does not look like it hits the trailing arm.




Maybe it's set up with a lot of negative camber and hitting the bump stop Hard?

[live free & drive]

If you are willing to use 6" or 7" x 16" Fuchs the tires below are very close to the original diameter at 24.8" and I bet will give good performance too:

https://www.tirerack.com/tires/tires.jsp?ti...0&tab=Sizes

[horizontally-opposed]

You can see the tire rubbing on the inner wheelhouse in the pic below, but it does not look like it hits the trailing arm.




Maybe it's set up with a lot of negative camber and hitting the bump stop Hard?

Saw that, and had same thought. My 914 did the same thing to its inner fenders with 205/60R15 Yokohama A-008R TU R-compound "balloons" back in the 1990s, but less aggressively. Had too much negative camber, something I fixed shortly thereafter. Never had inner fender issues again.

With the camber within spec, the first point of contact for a 215/60 on a 15x7R is the brake line on trailing arm. Relocating the line is easy enough; getting a bit more space there for a 215 is the trick. A 225 would presumably need that much more space at the arm, and would love the option to run either.

If you are willing to use 6" or 7" x 16" Fuchs the tires below are very close to the original diameter at 24.8" and I bet will give good performance too:

https://www.tirerack.com/tires/tires.jsp?ti...0&tab=Sizes

Very cool that the A-008P (with P being for Porsche) is available again, but want to stay on 15s.

Hoping Yokohama might add 225/50R16 for 911 fitments, and then the 195/65R15 & 215/60R15 A-008P that was long available. Had a set of 205/60R15 A-008R TUs and some of the very last 195/65R15 A-008P. Both were great for the street—so long as it was dry out.

Car on the A-008P from years ago seen below, on the day after Rennsport Reunion IV, I think—so 2011. My my, time flies…

[rick 918-S]

You can see the tire rubbing on the inner wheelhouse in the pic below, but it does not look like it hits the trailing arm.




Maybe it's set up with a lot of negative camber and hitting the bump stop Hard?

Saw that, and had same thought. My 914 did the same thing to its inner fenders with 205/60R15 Yokohama A-008R TU R-compound "balloons" back in the 1990s, but less aggressively. Had too much negative camber, something I fixed shortly thereafter. Never had inner fender issues again.

With the camber within spec, the first point of contact for a 215/60 on a 15x7R is the brake line on trailing arm. Relocating the line is easy enough; getting a bit more space there for a 215 is the trick. A 225 would presumably need that much more space at the arm, and would love the option to run either.

If you are willing to use 6" or 7" x 16" Fuchs the tires below are very close to the original diameter at 24.8" and I bet will give good performance too:

https://www.tirerack.com/tires/tires.jsp?ti...0&tab=Sizes

Very cool that the A-008P (with P being for Porsche) is available again, but want to stay on 15s.

Hoping Yokohama might add 225/50R16 for 911 fitments, and then the 195/65R15 & 215/60R15 A-008P that was long available. Had a set of 205/60R15 A-008R TUs followed by some of the very last 195/65R15 A-008P, and both were great tires for the street—so long as it was dry out.

Car on the A-008P from years ago, just after Rennsport Reunion IV, I think.

Love those tires (IMG:style_emoticons/default/aktion035.gif)
Hoping they come back with 255/50/16's

July 2007 WCR

[sixnotfour]

Fuch it and go 17s with a deep six lip look..This Kid likes em..
rub marks are from 7x15 Fuchs, 205x15

[rgalla9146]

That's 2" over the line.......my favorite T shirt

[horizontally-opposed]

That's 2" over the line.......

Lol! (IMG:style_emoticons/default/av-943.gif)

Rory, the principled man.

[Chris914n6]

My snark comes from experience (IMG:style_emoticons/default/biggrin.gif)

Your 215/60-15 are the only tires I call balloons. I even have a 225/60 but that pic might get you too excited (IMG:style_emoticons/default/drooley.gif)

A few more pics and I'll post why.

[Dave_Darling]

I agree that the market is very different today from what it was in the 80s and 90s. Back then, the only thing that mattered to most 914 owners was the price. If it wasn't cheap, they weren't buying it. Now, quite a few 914s are in the hands of people who are much more willing to spend money on them.

I don't know what kind of market there would be for aftermarket trailing arms, though. Might be an interesting project for someone, but I suspect that not enough people have run into problems with the 50-year-old steel parts to make that much of one, but my crystal ball doesn't work for crap! (I was absolutely certain that the Cayenne would never sell, for one thing.)

They would be neat, but they might wind up a one-off kind of thing.

--DD

[horizontally-opposed]

My snark comes from experience (IMG:style_emoticons/default/biggrin.gif)

Your 215/60-15 are the only tires I call balloons. I even have a 225/60 but that pic might get you too excited (IMG:style_emoticons/default/drooley.gif)

A few more pics and I'll post why.

Ha, 225/60 just a bit too F-150. (IMG:style_emoticons/default/poke.gif) (IMG:style_emoticons/default/happy11.gif)

215/60 no more "ballooney" than 185/70 or 195/65—matched O.D./sidewall height and was standard on the rear of RS 2.7, RS 3.0, early 930, SC, 3.2, etc. Also look pretty fantastic on the back of a 914…

[rgalla9146]

The wheel /tire combo most sixes actually left the factory with. A rare sight now.