Suspension upgrade project using Rebel Racing bits

[gsxrken]

After 11 years of my ownership, I've decided to address the 27 year old suspension on my 1986 930. It wallows around on transition and porpoises a bit on braking and accelerating, but it was still a tough call because I'm determined to keep this car enjoyable on the street.I've built a few cars and when the dust settled, they were more track oriented than I originally had in mind and I just don't end up using them much as a result.

To that end, I got a hold of Clint at Rebel Racing and spent a good half hour discussing in detail what I had in mind and how I use the car. 2 track days a year shouldn't dictate the setup for the other days of the year, but this car is ready for a firming up hopefully without any real impact to NVH.

We landed on 22 and 30mm torsion bars:


Custom valved Bilsteins to match the torsion bars"


Since every bushing on the car is a bone s-t-o-c-k 27 years old, I went with his front RSR bushing kit:


For the rear, Clint recommended Porsche rubber bushing for the banana arm to frame, but on the rear spring plates I tossed all concern for the wallet aside and purchased his RSR rear bushing kit:




Front and rear Tarett anti sway bars should tighten things up on transition when I do track the car, and afford me the ability to soften/tune them for the street for most of the year.




I also purchased a shock tower brace to further tighten things up without any bump harshness:

[jpnovak]

Just finished a similar upgrade on a friends 69S with original suspension. What a huge difference in how planted the car feels.

I always recommend suspension upgrades of this nature for those looking for a little extra out of their car.

[9Thirty]

Congratulations. I just a bought a full kit, Elephant racing street performance 2. I also chose a 22mm front, 30mm rear torsion, triangulated tower brace, sport Bilsteins and a bunch of other stuff, installation next week. Planning on lowering the car. Hope to feel a huge improvement. Let us know your thoughts after installation and a long drive.

[philip j]

Can't wait to hear your opinion after its done. Looks like this may be my winter project. Are you doing the install yourself? Philip

[gsxrken]

I am going to do the install myself. I have a nice work area, respectable amount of air tools, and this forum as well as shop manuals to help me through. You make a good point about a "winter project" because this is smack in the middle of the NorthEast driving season. I'd like to get the front arms powder coated and the rear trailing arms plated (any platers remaining out there or should I just powder coat them too?) which wil add time.
I want to get to just under Euro height or just to the point where I dont need raised spindles and bump steer setups.

[jsveb]

I have rebel racing bushings on my Carrera 3.0. Though I don't have many miles on it ( struggling with oil pressure problems) they are some awesome. It feels fantastic.

The 930 wil get a set when it is time for a refresh.

[speednme1]

Man those bits look too nice to put under the car. They need to be seen....quality looking parts. Did you get the bump steer kit?

[unclebilly]

I am running 23 and 30mm bars in my 77 track car with Weltmeisster sway bars and a strut brace. I think it might be a little harsh for your liking but maybe given the extra weight of the 930, it won't be too bad.

[gsxrken]

Originally Posted by unclebilly

I am running 23 and 30mm bars in my 77 track car with Weltmeisster sway bars and a strut brace. I think it might be a little harsh for your liking but maybe given the extra weight of the 930, it won't be too bad.

I hear you but can only trust that Clint is right here. My car was 2,877lbs with half tank of gas and no driver on some CB scales. We discussed squat on accel and with my future plans for more power went from his 29mm recommendation to a 30mm rear bar based on that.

By the way, having seen several "where is Clint?" threads here (but still desiring his bushings), I went with him and have to say my experience with Clint was excellent. We spoke at length about my build, and he shipped all the parts out the following day. They look excellent and were well packaged.

Now I just need to get started on this, and I'm beginning to have reservations about tying the car up for it. That and Jacob described this as "caveman" work in a similar thread! I'm going to need a solid block of time and not chip away at this an hour a night...

[JFairman]

It looks like you have the origonal fuchs on your car.
With 16" wheels and the taller sidewall tires that are available these days and fit on them have some sidewall squish to absorb bumps and that helps a lot to smooth the street ride when you have stiff suspension.

If you had 18" wheels with high performance 40 series tires in front and 30 series in the back the short sidewalls on those tires would definately result in a harsh ride for an all around street car.
Street ride comfort vs handling performance is to each his own opinion though.

The suspension parts you bought look really nice. I'm sure it's going to handle much better than before and in a big way.

The wheel size and tires you put on and resulting sidewall flex will have a lot to do with over all smoothness of ride now.

[Pimpim]

Price on this kit??

[fredmeister]

(Dont know your real name),
Those are nice looking components and your choice of t-bars is right on for what you have in mind.
I am running the same size hollow t-bars in my 79 930. It weighed in at 3090 lbs with driver and full tank of gas. I also replaced the bushings front and rear with elephant racing solid type except I left the OEM rubber bushing in the inner rear control arm mount just because I did not want to go thru the trouble and expense of removing and replacing that banana arm mount. I always wonder if I am losing a little precision with rear alignment during a track day with racing tires....but its hard to quantify. The car feels very good with the changes I made.
I also am running 27mm and 31mm Smart racing sway bars with the above.

Ride is firm but not harsh to the point of disturbing on city streets. I live near Baltimore so the roads are not glass smooth, but I also have not driven it over the wasteland they call streets in NYC and Detroit where I have lived before. I think its fine now and actually thought the stock suspension was too soft to give you an idea where I am coming from.
I think the hardest job for you is gonna be installing the front sway bar and its thru the body mounts in the frt fender well. With the gas tank in the car its difficult to work easily. You might want to consider removing it to make the job easier, keep it near empty before starting the job so you have the option of removing it during the job.
Removing the rear t-bars can get tough too if they are rusty. Good luck.

Fred

[9Thirty]

(Dont know your real name),

Those are nice looking components and your choice of t-bars is right on for what you have in mind.

I am running the same size hollow t-bars in my 79 930. It weighed in at 3090 lbs with driver and full tank of gas. I also replaced the bushings front and rear with elephant racing solid type except I left the OEM rubber bushing in the inner rear control arm mount just because I did not want to go thru the trouble and expense of removing and replacing that banana arm mount. I always wonder if I am losing a little precision with rear alignment during a track day with racing tires....but its hard to quantify. The car feels very good with the changes I made.

I also am running 27mm and 31mm Smart racing sway bars with the above.



Ride is firm but not harsh to the point of disturbing on city streets. I live near Baltimore so the roads are not glass smooth, but I also have not driven it over the wasteland they call streets in NYC and Detroit where I have lived before. I think its fine now and actually thought the stock suspension was too soft to give you an idea where I am coming from.

I think the hardest job for you is gonna be installing the front sway bar and its thru the body mounts in the frt fender well. With the gas tank in the car its difficult to work easily. You might want to consider removing it to make the job easier, keep it near empty before starting the job so you have the option of removing it during the job.

Removing the rear t-bars can get tough too if they are rusty. Good luck.



Fred

Did you have to carefully cut through your rear fender guard to remove the t bar?

[gsxrken]

Fred, thanks for the heads up on the gas tank. I'll consider what it looks like when I get further into it. I did just jump in tonight after I told myself I'll do the front first from start to finish before I tear apart the rear. When I first bought this car in 2002 I immediately had to do rear wheel bearings and those banana arms still intimidate me.

[jwasbury]

Great project Ken.

I made my life more difficult by opting for monoballs for the trailing arm to chassis mounts. Pretty much impossible to install without complete removal of the trailing arm. If you are just refreshing the factory rubber in there, I think you can do this with a "partial drop." I am sure that air tools will help. Looks like you already removed the ball joints...those were a real ***** for me, so you appear to be getting along smoothly.

Re: the through body front anti-roll bar, I think fuel tank removal is pretty much mandatory for installation. Its also recommended to weld the mounts in I believe, and weld the drop link attachment points onto the front control arms. Curious to see how you get on with this because I stayed with factory anti-roll bars, so this is another upgrade I could consider for my ride.

[JFairman]

I replaced the front control arm bushings and the rear springplate bushings with elephant racing polybronze bushings in my '87 over a year ago.
Then I installed Rennline monoballs on the tops of the front struts and in the rear trailing arms.
The feel of the car is tighter and more responsive to steering inputs than before with all the old rubber bushings.
It is also smoother over bumps because the suspension arms have much more freedom of up and down movement now.

I installed the trailing arm monoballs without removing the trailing arms from the car. I didn't even remove the calipers or the emergency brake cables.. I just disconnected the stainless braided brake lines I have on the rear brakes lines so I could remove the trailing arms far enough to do the work while laying on the ground under the car.
Call me crazy but thats how I did it and it wasn't easy but wasn't real difficult either.

After removing the large bolt the trailing arm bushing pivots on use a prybar to get it out of it's pickup point in the chassis. Then you can move it around enough to work on it under the car. I used a steel floor jack to hold it in place under the car while I was under there working on it.

Once the old bushing is out heat up the end of the trailing arm for a couple minutes with a propane torch and it expands enough that the monoball assembly slides right in easily. Then put on the retaining circlip and it's ready to install back into the chassis pickup point.

I used a 3/8" air impact wrench with socket on a 6" extension to remove and reinstall the bolt while holding the nut with a box end wrench.
I had to put another floor jack under the transaxle and remove the transaxle mount bolts so I could move the transaxle about an inch either way to have enough room to get a box end wrench on the nut thats real close to the transaxle.

Again, it wasn't real difficult... just took time and some uncomfortable positions crawling around and laying on the ground under the car while the back end of the car was up on jackstands while doing it.
If my back had been sore at the time I couldn't have done it but that wasn't a problem.

Good luck with your install!
It's very satisfying and a big improvement to the car when you're all done.

[jwasbury]

Originally Posted by JFairman

Once the old bushing is out

This is the part that I could not see how to do while laying under the car with the trailing arm partially disconnected. The rubber piece of the factory bushing comes out easy, but getting the metal inserts out so that the monoballs can go in was a real biotch. I ended up cutting them out with a combo of dremel tool and small hacksaw which I just could see my way to working upside on my back with the car on jack stands. How did you manage it?

[JFairman]

Yeah, that's the hardest most time consuming part of the whole job.

I have a 3/8" thick drift punch that I heated the business end up red hot using an acetylene and oxygen torch and bent over a little and then ground the end down at an angle so it will catch on a small inner diameter lip like the inside edge where those two steel inserts for the rubber bushings meet.

That's what I did laying under the car after heating up the end of the trailing arms with a propane torch for a couple minutes to expand them a little.
Aluminum expands more than steel so once it's hot enough the steel inserts will gradually drive out when you keep hammering on the punch and alternating sides of the steel insert. It takes a while, and some patience.

Once one side of the steel insert had popped out I took a half inch drive socket that fit inside the end of the trailing arm but would stop when it came up against the other half of the steel insert that was pressed into the other side.

Heat up the end of the trailing arm with propane again and hammer on the socket I'm using as a drift with a brass hammer and that one slowly drives out. It's a lot easier then the first side with the hand held skinny punch.

To keep the end of the trailing arm in place while doing all this I had a floor jack under the trailing arm and had it pinned up against the bottom of the car and sway bar to hold it still while hammering on the drift punch. It worked and was less work for me doing it this way then taking apart the emergency brake cable and removing the entire trailing arm first.
I was laying on my side under the car while holding a punch and swinging a ball peen hammer and it was not comfortable but I got it done.

Thats it. I used to work full time as a mechanic on european street cars around 25 years ago and always worked on my own cars rebuilding motors and everything else so this kind of stuff just isn't difficult for me to figure out and do... I'm almost 58 now and can still do this stuff as long as I don't have a sore back

[Flieger]

Good choice on parts. The bushings really improved the ride on my car, but that was compared to old urethane pieces of crap that were so bound up and squeaky that the front end didn't seem to move at all. The Rebel Racing bushings made it ride like a Cadillac in comparison. Also, your choice of 22/30 should be fine. I recently upgraded from 22/27 to 22/29 and the car has a much more level ride- it doesn't pitch and bounce in the rear over bumps now.

I think my car rides just fine. I'd actually like it a little stiffer at least in pitch. It's got monoballs on the trailing arm and strut tops, Rebel Racing bushings for the A-arms and spring plates, 22/29mm torsion bars, 22mm front and rear sway bars, and it weighs about 2000 pounds without a driver.

I should also disclose that I am 23, so it might be a little harsh for others here. However, I did drive it 170 miles (one way) up to Morro Bay to see Clint and back and it was the most comfortable car I ever made the trip in, though that is mainly due to the seats and belts.

[Flieger]

Also, you may need to do some sanding of the torsion tube and filing of the aluminum insert in order to get the spring plate bushings to install properly. There is a lot of variation in that area from the factory it seems. The rubber bushings didn't really need a precision fit.