Results of Suspension Upgrade

[wswilburn]

I finished my suspension upgrade today and thought I would post the results to help others.

The car (1988 Carrera) is mostly a daily driver, but is autocrossed 5-6 times a year. Most of the new parts are Elephant Racing.

Parts
-------
ER 22/29 mm hollow torsion bars
Bilstein HD (front) and sport (rear)
ER Polybronze bearings for spring plates and control arms
ER control arm mounts
ER monoball trailing arm mounts
ER sport rubber upper strut bushings
Stock rear wheel bearings
Stock ball joints
Turbo ties rods
Stock front stabilizer bar bushings
Kept existing adjustable rear stabilizer bar (man. unknown)
Kept existing camber brace (Stable Energies)
Wevo semisolid engine mounts
Hankook Ventus R-S2 225/50R16 (rear) 205/55R16 (front) (from last season, rears bald, will order tonight)

Impression of parts
-------------------------
All the ER parts were high quality
Instructions were clear
Chuck Moreland readily answered my few questions

Installation experience
------------------------------
What can I say, suspension work is always hard, especially on 20+ year old cars.

The hardest part was removing the spring plate bushings, but you're stuck with that job regardless of whether you are replacing with stock or upgrading. Keep applying heat and scraping. It comes off a little at a time. Plan a few hours per side.

The ball joints required heat, a pipe wrench, and a BFH to remove.

A hydraulic press really helps for some steps (thanks Jim).

Engine drop required for trailing arm bushing replacement.

The front torsion bars didn't smoothly engage the splines on either the body or the adjusters. Had to be tapped in with a mallet.

It took me 2-3 tries per side to get the rear ride height set. Not difficult, just patience required.

Corner balance and alignment
------------------------------------------

Initially set fender heights to 25" (rear) 25 1/2" (front). Only had to adjust LF height for corner balance.

Corner weights tuned for equal diagonals (177 lbs added to driver seat):

662 581
954 877

Front camber: -1.0 deg.
Rear camber: -2.1 deg.

Front toe: 0
Rear toe: 8.5' (in)

Rear stabilizer adjusted for no preload.

Would have preferred -1.5 deg. on front camber, but couldn't get more that -1.0 deg. on one side.

Driving impressions
---------------------------
Have only driven around town a bit, spirited, but not overly aggressive.
Steering is very precise and tight.
Ride is not at all harsh, even on old pavement.
Very stable (max. speed so far 55 MPH), does not wander.
No appreciable body roll in turns.

Summary
-------------
Well worth the time and money.
Can't wait to try an autocross!

[gduke2010]

Sounds like a fun car. The upgrades make a big diff. and like you said, "not a harsh ride." I put the ER bushings on my car and the ride smoothed out.

Also, nice to drive a cornerbalanced and aligned car.

gary

[efhughes3]

You're leaving improvement on the table with your shocks, as yours won't match the heavier springs. One of the great things about Bilsteins is how easy it is to get them valved to suit.

[wswilburn]

Thought I would give an update. Here are the things I have learned since the last post.

1. Stiffening the suspension revealed the steering was loose. Rebuilding the steering rack (replacing the bearings and grease) did the job.

2. As others knew, but I didn't, changing cambers affects the corner balance and vice versa. Since a good corner balance is more important than perfect camber, do that last. I've iterated once since my last post, and have a good balance, but the cambers are a bit different L-R. I plan to go another round to get them closer.

3. Ed was right. Matching the shocks and strut inserts to the springs is important. Much more than I realized. I sent them off to Steve Weiner at Rennsport for revalving and he did a great job.

The end result is I am now very happy with how the car drives. On the street it is definitely not too harsh. I've done one autocross since the revalving, and it was my best performance ever. The car felt flat in turns and slaloms, and was very stable. I was able to forget about what the car was doing, and focus on my driving.

[fasteddie99]

Rennsport did mine very similar to your build. Transformed the car. You will be very happy.

[steely]

Good for you - on the work - and thanks for posting this.
I am doing my front and just keeping it stock (and it's just street), but I was glad to see you touched on some points that I stumbled onto myself - made me feel I was on the right page.

Thanks too for the insight regarding the rear, as I was planning that for next year. For example, I didn't realize a drop would be needed to do the trailing arm bushings.

[michael lang]

Scott, in order to install the rear monoballs, why did you have to drop the engine? I'm curious because I have right now a brand new set of ER rear monoballs in my garage with my car on jackstands that I was literally about to start taking apart to install the monoballs and a pair of adjustable spring plates. I don't want to get to a point of no return and be in over my head.

[wswilburn]

Mike,

I was unable to get a wrench square on the bolt heads with the transmission in place. Also, they required a huge force to break loose (breaker bar + pipe) that I probably couldn't have gotten enough torque if I could have found a wrench to fit the close geometry.

No harm in trying though, as long as you don't round the head on he bolt.

Also, some have reported success using a Sawzall, but I couldn't see how to get it in there.

I have a G50, not sure it is the same for a 915.

[wswilburn]

Dan,

The drop is really only required if you are replacing the bushing where the trailing arms attach to the body, like Mike is doing.

[efhughes3]

Nice!

I will say that when I put my ER rear monos on a few years back-breaking the bolts loose on the trailing arms was one of the toughest things I've ever come across. I was able to do with the motor/trans in place. But I ended up with about an 8' long lever arm and my 210lbs to budge them.

[Wil Ferch]

Some comments on your corner weights--->

662 581
954 877

....with a 177 lb load on the drivers seat...based on my experience and past notebook calculations....this 177 "driver" is *probably* added this way over an empty car--->

72 13
59 33

So....if we remove the 177 lb "driver".....I'm gonna guess your bare car is---->

590 568
895 844

My point?...not bad....but you can do better. Look up an old thread where Randy Blaylock taught me a few things....like the idea that "perfect" corner balance may not be the ideal target. That instead equal fronts may work better ( to avoid premature one-wheel lockup), as a compromise that "turn-in" may now be a bit different turning-right vs turning left. The argument made that equal turn-in can be compromised for more consistent threshold braking.

Altogether....I grudgingly admitted was a good idea and a fair trade-off from "ideal".

[NoLift911]

Originally Posted by wswilburn

Thought I would give an update. Here are the things I have learned since the last post.

1. Stiffening the suspension revealed the steering was loose. Rebuilding the steering rack (replacing the bearings and grease) did the job.

2. As others knew, but I didn't, changing cambers affects the corner balance and vice versa. Since a good corner balance is more important than perfect camber, do that last. I've iterated once since my last post, and have a good balance, but the cambers are a bit different L-R. I plan to go another round to get them closer.

3. Ed was right. Matching the shocks and strut inserts to the springs is important. Much more than I realized. I sent them off to Steve Weiner at Rennsport for revalving and he did a great job.

The end result is I am now very happy with how the car drives. On the street it is definitely not too harsh. I've done one autocross since the revalving, and it was my best performance ever. The car felt flat in turns and slaloms, and was very stable. I was able to forget about what the car was doing, and focus on my driving.

Curious about your shock revalving with the 22/29 combo...how did you arrive that they needed to be revavled? I have 22/29 on my car (yet to touch the ground) and went with Bilstein sports all around...I notice you went sports in the rear and HD in the front.

What did you wind up with with the "revalving"? I think Chuck mentioned that with the 22/29 sports were a good setup.

Thanks

[efhughes3]

Two things:

Car should be balanced with equivalent driver weight in the seat.

22/29 t-bars definitely benefit from valving. I drove with sports for two years and thought they were fine. THEN, I had Jae at Mirage revalve. I then knew what fine truly was.

[michael lang]

I was pretty set on doing it myself but I think I may be better off having a professional tech do what I have planned. I had no idea taking off the trailing arms was going to be such an ordeal. I definitely don't want to screw anything up.

[mtb001]

I did trailing arm bushing with motor/tran in place but had to cut the bolts with sawzall and replace.