coilovers on an SC street/DE car?

[twobone]

A car I'm looking at has coilover shocks

Are they usually just as tunable as a torsion bar swap?

If they are too stiff, is it as simple as a coil swap?

Thoughts and experiences?

[JMatta]

Coilovers are very easy to adjust due to their threaded shock bodies. Simply turn the adjuster one way or the other for height. You can also substitute various spring rates depending upon your end goal. For street use, they are over-kill; stick to torsion bars. But for track use, they are indespensible.

I run coilovers on the rear of my car and torsion bars on the front...best of both worlds.

[rusnak]

it depends on the manufacturer I'd say. I have the Bilstein RSR struts in mine, and they are able to be re-valved, but not "tuned" like Konis or Fox shocks. When you say "too stiff" I think you might be talking about the springs. Sometimes they can also sag, and then they will seem too stiff because you've had to shorten the travel by raising the ride height. The springs are not tuned or adjusted, just changed. It's a piece of cake. Ride height is also easy to adjust. I'd find a good parts guy who can take your existing spring information and find out what spring rate you have, and then order springs that are more to your liking. Install them, and disconnect the sway bars. Try to get the springs and shocks a close as possible, and then reconnect the sway bars and do fine tuning by changing or adjusting the sway bars. Alignment and corner balancing of course comes last.

If in the end you don't like the coilovers, sell 'em. I'll send you a full set of torsion bars out of my '84 3.2 Carrera in trade.

[scottbooth]

JMatta, why is a torsion bar front and coil over rear the best of both worlds?

I am still considering doing a coil over rear suspension in my 78 SC track car and was wondering about leaving the front as-is to save some money, at least for now.

Thanks
Scott

[Noel]

Remember that since these cars were never designed to have coilovers/struts, the upper mounts must be reinforced prior to the conversion.

[scottbooth]

Yes, I am planning to reinforce the rear whether or not I do the coil overs. I figure the added stiffness can't hurt if I end up waiting on the upgrade.

[rusnak]

I have the coilovers in front, torsions in the rear. The reason is that when you lower the car, you lose suspension travel. In the rear, it's not such a problem. But in the front, you need to raise the spindles. I therefore have the RSR struts with the spindles raised 13mm which are also very beefy and reinforced with steel plates.

I now have a lowered car with plenty of suspension travel to work with. As for stiffness, I went with soft springs so that I can keep all 4 wheels on the ground even over bad roads, of which there are plenty in the central California coast.

[sl951]

torsion bar front and coil over rear the best of both worlds?

Rear:
It's harder to adjust ride height with rear torsions. Coils make this just easier. You should reinforce the top strut tops if you go coils.

Front:
A front coil springs will limit the amount of negative camber and sometimes tire width you can add (coils will end up rubbing against the chassis or tire). It will also increase steering effort even if you get those coil-spring bearing things (dirt accumulates in the bearings over time). With front torsion bars you don't have the above issues and frankly ride height adjustment is easier (IMHO). Swapping out front bars is easier....

------------------------
The biggest advantage of coils is the broad range of sizes/stiffnesses available. And the ability to have double-stack springs etc.. etc.

[rusnak]

I've read that the RSR struts will not allow any negative camber because they were designed for bias ply tires, and negative camber was not desirable to run with them. Radial tires need more negative camber, and therefore RSR struts are not the way to go. However, I have been able to adjust 1.5 negree negative camber on mine. I personally don't like that much negative camber, just know that it's possible. I run 1 degree negative and it's fine for my driving.

As for the bearings, you have to install them between the bottom perch and the bottom coil. If you install them at the top, then yes you will get a lot of dirt. Install them at the bottom, near the center of the wheel, and there is very little dirt accumulation there.
------------------------
The biggest advantage of coils is the broad range of sizes/stiffnesses available. And the ability to have double-stack springs etc.. etc. [/B][/QUOTE]

[sl951]

Originally posted by rusnak
I've read that the RSR struts will not allow any negative camber because they were designed for bias ply tires, and negative camber was not desirable to run with them.

I had RSR front struts on mine. No negative camber..designed for bias ply tires? I've never heard that one before.

In the front, you can gain negative camber via 3 methods... move the strut tops in (i.e camber plates), change the length of the a-arm, or change the angle of the spindle.

On the RSR struts the spindle to strut housing angle was the same as stock, the only difference was the raised spindle... so pushing the strut tops toward the center of the car will create more negative camber, just like stock. If you have a coil-spring on it, the coil will hit the chassis at the limit. I ran 2.0 on my 16 Fuchs.. do a search, for DE's 1.5-2.0 fronts and 2.5-3 rears is common.


As for the coil-thrust-bearings.. I did have them in the center so the spring sat on them. After a couple of years of water and dirt, bearings are toast... then you get coil-binding and increased steering effort at low speeds.

[Jeff Alton]

I have coilovers on my car front and rear. I run the ERP 935 front suspension and TRG rear spring plates. I have used rear coilovers from FOX, TRG and bilstien (in varying valving). Up front I have used TRG and three different bilstiens.

Negative camber?? I run -2.5 and I could probably get at least -3.5 with out any effort. Mind you, with the 935 style a-arm I can lengthen it to make more negative camber possible.

I am impressed with how well a coil sprung 911 rides on the street. Not that my car sees much street use, but it has between 30-50% more spring rate than it did with big torion bars and it rides better. Way stiffer, and a better ride.

Now, for a street occasionaly DE/Autocross car, I say stick with big torion bars and revalved shocks. Easier on the pocket book. Plus, with the suspension my car has, I am not sure I can drive it too its limit. Fact is, the driver is the weak link in most modified 911's, be it with torsion bars or coil overs.......

cheers

[rusnak]

sl951, well now you have heard, so consider yourself more um...learned. And well yeah, if you leave those bearings uncleaned and unlubricated for a couple of YEARS then what else would you expect? No one who drives a 911 should expect maintenance free driving. And since you are doing DEs, why would you not be cleaning and lubing these parts after every event???

I could use torsion bars with my RSR struts. I think the early RSRs may have changed between coils and torsion bars, based on some of the factory photos in Paul Frere's book "911 Story", which show both coils and torsion bars as part of the original suspension. Anyhow, I am also impressed with the way coils work on the street. I opted for a more supple suspension with medium damping. The suspension works very hard, absorbing road bumps and keeps the tires in contact with the ground. One of these days I'm going to post a picture of my 911 with all 4 wheels articulated at different angles and the car riding absolutely level. I don't use my 911 for racing so I don't need a really stiff suspension. In my world, I don't have time for DE (wish I did), so street driving is my one and only priority. Some racing parts do find their way onto my car, and when they work out, I keep em on.

[barney911rs]

If the car you are looking at already has them installed, I'd consider that a bonus if you are planning track use for this car.

As my time permits, I'm putting my new suspension on my race car. I needed to go to higher spring rates then I was able to achieve with torsion bars. One limitation to only doing the front or rear, is that you have to keep the spring rates in line with the torsion bar on the other end or it will get way out of balance. After talking with my vendor, I bit the bullet and found a set of used Bilstein front struts for him to make the conversion to. In addition to providing the threaded collars (square groves like the original RSR) and associated hardware, they raised the front spindles, and had the front inserts and rear shocks re-valved to match the springs we we planning to use.

A side benefit is that I can change the spring rates and ride heights relatively easy.

[rusnak]

Barney, is your vendor using new spindles, or at least re-surfacing the old ones? Have you taken a look at the Smart Racing setup? It looks to be superior to a Bilstein conversion. Another consideration is that the steering arm is beefier on the RSR and SRP struts, and the spindle is gusseted and reinforced to cancel spindle flex.

[twobone]

I pulled the trigger on the car...it is amazing

The front strut towers are fully braced...not the rears...big deal?

[Jeff Alton]

Ummm we need some pics!

Normally, one would re enforce the rear before the front......

Cheers

[barney911rs]

I got all my parts from Clint Smith at Rebel Racing Products. He came highly recommended from this forum. They look brand new. The used struts I bought were from a turbo, which Clint said was an advantage, but I don't recall why.

Rebel Racing Products

The rear bracing won't be a huge issue right away, but you should plan to add it down the road. Congrats on the new car. Pics soon please.

[Jeff Alton]

I now have Clint's stuff on the rear. It looks really nice. I have used the TRG upside down, TRG right side up, Bilstien RSR, and FOX previously. Clints stuff in very high quality. The shocks were new and revalved. I have not driven on them yet, but they look good.

On the front now use a RSR 19mm raised strut (valving by Steve W at Rennsport)with the SRP bumpsteer kit that I further lengthened and gusseted to the steering arm. I tried the "long" verion of the bumpsteer kit but when I measured the bumpsteer I decided I wanted to try and lessen it, hence the added length.

Cheers

[Jeff Alton]

Here is what I am talking about....

This is the Rebel stuff on the car....



And here is the RSR strut with modified bump steer kit....



Cheers

[sl951]

Originally posted by rusnak
sl951, well now you have heard, so consider yourself more um...learned. And well yeah, if you leave those bearings uncleaned and unlubricated for a couple of YEARS then what else would you expect? No one who drives a 911 should expect maintenance free driving. And since you are doing DEs, why would you not be cleaning and lubing these parts after every event???

Not sure what I learned here. You stated RSR struts can't provide negative camber... that just not true. And if is please send a link to more info or provide an explanation about the strut that doesn't allow this.

If you can get the appropriate front torsion bars in the size you want it saves time to not have to clean and lube those extra coil-thrust bearings.

I'm not saying one is better that the other, just pointing out the diffs. Coils come in a better range of stiffnesses. There are issues with torsions too.