Suspension upgrade project using Rebel Racing bits
 

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:
https://lh5.googleusercontent.com/-Y...o/DSC_0697.JPG

Custom valved Bilsteins to match the torsion bars"
https://lh4.googleusercontent.com/-X...o/DSC_0705.JPG

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:
https://lh3.googleusercontent.com/-H...o/DSC_0699.JPG

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:
https://lh3.googleusercontent.com/-y...o/DSC_0701.JPG

https://lh6.googleusercontent.com/-4...o/DSC_0700.JPG

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.
https://lh6.googleusercontent.com/-Y...o/DSC_0702.JPG
https://lh3.googleusercontent.com/-t...o/DSC_0706.JPG
https://lh3.googleusercontent.com/-O...o/DSC_0707.JPG

I also purchased a shock tower brace to further tighten things up without any bump harshness:
https://lh5.googleusercontent.com/-3...o/DSC_0704.JPG

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.

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.

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

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.

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.

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

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...

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.

Price on this kit??

(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?

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.
https://lh6.googleusercontent.com/-C...5208_21_27.jpg

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.

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.

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?

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:)

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. :D 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.

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.

I would like to add to what Ken stated about Clint. I too ordered parts(935 spring plates, front and rear bushings) yesterday(Kenny's fault..lol). Parts were shipped out this morning. Clint was vey personable and easy to talk to.

Jacob, I hadn't heard that welding the mounts in was advised, but I haven't even read the directions yet. Is it under any stress? I wouldn't have thought it should even touch the bar, but again I haven't gotten this far yet.

Jim, thank you for posting your approach here. I will definitely attempt to follow how you did it, rather than tackle the much bigger job of removing the arms again. I was 10 years younger but I think that wheel bearing job still took me over 10 hours to do both sides. If I knew any better then, I would have changed that bushing when they were out.

Thanks for the heads up. Maybe the freezer and the torch can help out here too.

Speed- don't blame me for your own insanity. You have to start a thread on what you're up to. Clint's bushings don't even constitute a rounding error on your ride!

I'm glad to help with descriptions like that.

I don't remember removing any of the CV joints and axles either. I think I even left the rear shocks attached to the trailing arms to hold the heavy end up.
I have tarret adjustable rear sway bar drop links and I did unbolt them from the spring plates. I have weltmeister adjustable spring plates on the car.

It's heavy with the rotor and caliper still on it but you can move it around enough and pin up the small end against the sway bar with a floor jack to hold it in place while heating up the small end and hammering out that steel sleave the origonal rear bushings are pressed into.

The front arms are off to the powder coater.
I have no idea how my control arms even moved on those bushings. Besides being out of round which you can see somewhat in this pic, the arm barely moved even after it was free of the strut ball joint. It just stuck out and if I pushed it down, it mostly twisted the bushing and popped back up when I released it.
https://lh4.googleusercontent.com/-p...7_+8_21_28.jpg

Getting them off is easy, a little heat and then when the bushing starts crackling, just twist it all off with a screwdriver.
https://lh4.googleusercontent.com/-0...7_+9_13_51.jpg
https://lh6.googleusercontent.com/-8...7_+9_13_51.jpg
https://lh4.googleusercontent.com/-5...7_+9_13_51.jpg

After four of them, you can detect the smell of rubber in any room of the house.
Smells like... victory.

The Tarrett bars require the old style (pre-73) sway bar bracket. So I had to remove the loop on each arm:
https://lh4.googleusercontent.com/-a...7_+9_13_51.jpg

Chisel off the remains of the sway bar end loop"
https://lh5.googleusercontent.com/-u...7_+9_13_51.jpg

And grind it all away to make room for the older bracket:
https://lh3.googleusercontent.com/-k...7_+9_13_51.jpg
Here's a shot of the new style:
https://lh6.googleusercontent.com/-w...8-no/image.jpg

Into the parts washer and then off to the powder coater:
https://lh6.googleusercontent.com/-v...7_+9_13_51.jpg

Mask off the areas where you will be epoxying the race onto the arm. That will save you the trouble of sanding it off later.

To be clear, the arm is not supposed to move in the rubber bushings. That is what makes them "silentblocks". The suspension motion is accomodated by the rubber twisting like a torsion bar (it does add a small amount of spring rate). Clint's bushings use a dry lubricant so that there is a smooth rotation while getting rid of the deflection of the rubber in the radial and axial directions which cause the alignment to change.

I would recommend against the hot&cold method when fitting the bushings. The fit is tight already and it could make something bind if it is shrink-fitted and expands to be out-of-round. Clint has a small portable lathe to allow him to reduce the diameter of the aluminum piece if the torsion tube is really bad (like one side of my car was) but normally it is rusty and so a pick and various tools in an electric drill will get the diameter back to round enough. It can be a little loose because the epoxy will take up the gap and when you assemble everything without the torsion bar it ensures that the epoxy sets with the bushing properly aligned.

Wow Ken, that is some serious work there. I need to get my skills up...:(

Not really required to remove the tank. I think I did it with it in place but it made getting to the reinforcement plates more difficult. Its been awhile so I dont remember exactly how I did it.
I was able to remove the rear t-bars through the small round hole in the rear fender that is covered by the cover plate. Its just removed with the small little nut that sandwiches it between the inner and outer wall of the fender.

Its gonna be a nice project tot ackle and the ride will be much improved in the car.

Fred

I got my control arms and front tow hook covers for them back from the powder coater. I had welded on the drop link bracket prior to PC so now it's all nice-nice in a chassis black coating.
I made sure he didn't coat the bearing surfaces, and I just checked and the RSR bushings slide right on with no issues. Perhaps Flieger you were only referring to the rear plates.
In either case, I can resume the front end assembly.
https://lh6.googleusercontent.com/-b...7_12_18_49.jpg

I did some searching on welding in the sway bar brackets due to Jacob's note. Actually, I couldn't find reference to welding in the triangular bracket, but there are a few examples of guys welding in a reinforcement piece of metal around the area were the bar passes through the tub. The 914 guys seem to sandwich the tub sheet metal with two thicker pieces and drill through all three to beef up the area. But in general it appears that as long as the bars adjustment are within the proper orientation, it is not necessary. It appears that when the link is adjusted near straight up or straight out and cannot articulate further, then the bar can go solid and introduce way too much stress to the bushing area and tear the sheet metal. The vast amount of users of these bars have had no welding nor any issues.
I'll post up more progress when I can get back under the car... I'm up to my nose in a bathroom remodeling project as well.

I meant both. Powder coating usually makes shafts too big for the race to fit over. Looks like everything is good.

A few progress notes...
One of the leaps of faith with the through the body sway bars (on the later cars that did not come with them) is drilling the sheetmetal for the bushings. The Tarrett instructions assume you have the holes already, and if not, see your authorized dealer for the adapter mounts and control arm u-channel.
There is an indentation under the stock body schutz where you can see where a sway bar might go. I buzzed off the undercoating with a wire wheel and got down to this:
https://lh3.googleusercontent.com/--...7_17_22_+2.jpg

The next step is to drill out an 1-1/8" hole and the three holes for the bushing-to-bracket bolts. Again, there is some trepidation in drilling into the tub irreversibly and without any sense of precision...
https://lh3.googleusercontent.com/-Z...7_17_22_+2.jpg

On the passenger side, it was easy to use a telescoping magnet to maneuver the backing plate bracket down to the new holes, catch it with my fingers and secure it with the bolts. The drivers side was a bit more challenging, but snaking a coat hanger from the wheel well through the holes and up alongside the gas tank allowed me to loop the bracket onto the coat hanger and then fish it back out towards the hole until I could catch this one with my fingers as well. Absolutely no need to remove the gas tank on this 1986 930.

A trial fitting of the bushing to make sure I could catch all three bolts:
https://lh6.googleusercontent.com/-C...7_17_22_+2.jpg

And then a quick touch up with rattle can on the exposed metal, and miraculously the sway bar slid right through one bushing and appeared through the other one on the far side. I was relieved that it lined up so well! I can twist the bar with a thumb and forefinger and it spins with very little effort.
https://lh6.googleusercontent.com/-c...7_17_22_+2.jpg

I installed one control arm with the new bushings, and after some fiddling with the concave/convex washer, got it nicely adjusted so that it falls from horizontal to vertical from its own weight. I now need to do some searching on how to set the torsion bar adjuster end cap. I'm not clear on what postion the arm should be in when I try this.

Some people turn the clevis on the A-arm 90 degrees from the factory orientation so that the bolt goes laterally and is therefore parallel to the sway bar axis. Gives more freedom for adjusting the bar and the other axis of misalignment isn't as critical with lowered, stiffened cars. You can basically just assemble the sway bar and put the A-arm at the angle it will be when on the ground and see where it needs to go, then just try to match it to the other side.

Mine is in the factory orientation.

http://farm6.staticflickr.com/5257/5...de5de6ee_z.jpg
Front Suspension Geometry_ 019 by Max_911S_fahrer, on Flickr

A great idea but I already welded mine in the stock orientation prior to powdercoating. Clint had sent a picture with the center to center measurement and I zapped it in.

I have all but finished the front suspension work. I have the control arms on new bushings, the sway bars installed and finger tight for now, the new strut inserts installed, and the 22mm torsion bars in place. I really need to have the car down on its own weight for the next steps to tighten everything up and adjust the sway bar down link length. One of the next steps is to figure out where I need to put the torsion bar adjuster. With the new bushings, the arm swings down as far as the strut will allow it. I'm not sure where to orient the splined adjuster arm so that it will be roughly centered in the crossmember when I'm at my desired ride height. I guess it will be a trial and error process.

https://lh6.googleusercontent.com/-Y...7_21_21_30.jpg

https://lh6.googleusercontent.com/-t...7_21_21_28.jpg

https://lh5.googleusercontent.com/-e...7_21_21_28.jpg

https://lh5.googleusercontent.com/-q...7_21_21_28.jpg

Forgot to mention the easiest part of the job- probably because it was so easy it took up no bandwidth. The strut tower brace is installed by removing tow of the upper strut mount bolts and replacing with two longer bolts that secure the bar's eyelets. Couldn't be less drama.

https://lh4.googleusercontent.com/-i...7_21_21_29.jpg

The rest of the work is decidedly more time consuming. If it wasn't for a nice array of air tools, I would probably have maimed myself at some point, and from a time standpoint I would definitely still be out there. As it is, I need only to lower the car and adjust/tighten everything and take it for a ride. I've lost 2 weeks of in-season seat time and might wait for later in the year for the rear. Kind of not in the mood for it right now, either.

C'mon Ken, time to cowboy up and finish that rear..lol. Jk man I know you have other things going on. The front came out sweet, can't wait to see it on the ground.

Time for a few more updates. I have completed the front end. The control arm adjuster "ears" were fine right where I had them. With the suspension at full droop, I installed the arm as far down as it could go in the crossmember and put maybe three or four threads of the bolt showing. When I put the car on the ground, it was too low but reaching under and cranking in a few turns and I'm back at my original ride height.

I set the front Tarrett bar to the softest position; I don't know whether at that setting the new bar is even as stiff as my 1986 stock (larger than earlier turbos) 22mm bar that I removed. In any case I thought I'd start there, and I took the car out for a quick 5 mile spin. I must say I need to move on to the rear refresh sooner rather than later. The car was definitely smoother in hitting road imperfections, which is a bit counter-intuitive since I removed rubber bushings and replaced with teflon-like bushings throughout) and the front end was definitely firmer on low-speed dips and whoops in the road. But the car still waggles on quick right-left, right-left jerks of the steering wheel. Of course the rear suspension is 27 years old and has 100k miles on it, but if there was ever any doubt, the rear suspension is as important as the front in terms of responsive turn-in. So I will move onto the rear work next week rather than wait til winter.

I also jumped at the opportunity to get some very nice Forgeline's from a friend of Rey's. They are 17s, which to my eye still fit the era of the car while offering a stiffer sidewall and a wider tire choice than my stock 7x9 16s (albeit not as wide a choice as 18s).
https://lh4.googleusercontent.com/-R...7_26_12_35.jpg

Right now as Rey said above, I'm all over the place. One of the bathrooms is completely under renovation to restore balance in the household given the 930's recent updates.
https://lh5.googleusercontent.com/-q...7_26_12_45.jpg

And now we're off for some time upstate for some ATV and 2nd Amendment exercising. So the car will have to sit a bit more.
https://lh5.googleusercontent.com/-O...7_26_12_47.jpg

Looks good Ken.. You will really enjoy the ride with Clint's stuff. I have it in my 930, but the car is not done yet. I did a full set up, including coil overs on a friends Carerra and he loves it.

Those quads look like fun!

You are making the right decision to do the rear right away. It controls the behavior of the car. That is why Porsche went to so much effort with the passive rear steering on the 964, then the multilink 993,996,997, and now the active rear-steer 991 GT3, all the while keeping the tried and true strut setup on the front.

Beautiful work!

Thanks Fraggle and welcome to the board.
I began the rear suspension work this weekend.
First one needs to disconnect the rear arm from the spring plate. Before fully disconnecting, I took an angle measurement with an inclinometer level:
https://lh4.googleusercontent.com/-H...8_+5_19_+5.jpg

to get the torsion bar out, I needed to pull off part of the rubber trim and peel back the vinyl black sticker on the rear quarter:
https://lh5.googleusercontent.com/-7...8_+5_19_+5.jpg
Then I could remove the cover plate on the rocker so the torsion bar could come out.
https://lh6.googleusercontent.com/-Q...8_+5_19_+5.jpg

https://lh3.googleusercontent.com/-7...8_+5_19_+5.jpg

Bushings in both arms were deformed where the rubber had cold-flowed around the weight of the torsion bar supported car. These provided years of good service and deserve retirement now.
https://lh4.googleusercontent.com/-w...8_+5_19_+5.jpg

Down to the torch, vise and wire wheel grinder to get the bushings off and cleaned up:
https://lh6.googleusercontent.com/-Z...8_+6_12_17.jpg

As the directions suggest (and Flieger pointed out somewhere in this post), the arms required a few passes with a flat file to allow the inner bushings to slide on:
https://lh3.googleusercontent.com/-N...8_+6_12_17.jpg

Last shot of bushings oriented loosely on the arms before I JB-Weld the bushings on and had to quit:
https://lh6.googleusercontent.com/-a...8_+6_12_17.jpg



This job is very doable by the backyard mechanic. Air tools make it easier but there is just no rushing possible. The car is going to down for a while unless you can blast out 8 hour days in succession. And I have yet to tackle the frame bushing. JFairman posted that it is possible with the arms in the car and I am going to try that soon.