rear coliovers on a Carrera

[Mike the mechanic]

Hey guys, I am curious, what is invloved in installing rear coilovers on a Carrera?

Do you just renove the torsion bars alltogether?

I guess if you do, you need a monoball pivot at the swingarm?

Do the upper shock mounts need to be reinforced?

Is there any disadvantages to having rear coilovers on a mostly street car? It will be tracked about once a month.

Thanks in advance for any input.

Mike
86 Carrera (soon tt)

[Chuck Moreland]

The reason to go with coil overs is to achieve a higher spring rate than you can get with tbars, and perhaps save a couple pounds. Some people find them easier to adjust for height. And they normally have double adjustable shocks. These things are really for balls-out race cars that are tweeked and adjusted all the time.

Since you can get man-sized tbars that are easily as big as you'd want for your mostly-street car, there really is no reason to put coil overs on your car.

But if you did decide to put them on you can retain your existing spring plates, just pull out the tbars. You should reinforce the shock tower mounts and tie them into your roll cage. I know people who run coil overs without the reinforcements. Time will tell if these hold up.

[Wayne 962]

The hollow bars can give you greater stiffness, without too much extra weight...

-Wayne

[APKhaos]

Chuck said it. The max rear Tbar size is limited to around 31mm, although I've seen a rare 35mm custom bar being fitted to a hightly competitive track car.

If you want a higher spring rate than the that, then coilover is the only road. Probably talking dedicated track use, with roll cage tied in to reinforce the upper shock towers.

[CamB]

I have read that the later RSR used "helper" coil overs in conjunction with big torsion bars.

I also understand the shock towers are not strong enough for any meaningful spring rates (ie standalone).

Cam

[Mike the mechanic]

Guys, thanks for the responses, greatly appreciated. I failed to mention that the main reason for asking this question is. I plan on installing a g50 tranny and I just can't justify the cost for a short bellhousing conversion. I mean it's close to $2000 for the conversion to the tranny alone. I am also entertaining the thought of installing a 6-speed. which would require cutting at the torsion tube anyway you look at it. The way i see it, the coilovers would be a great solution and give me all the adjustability I would ever require in the long run.

Mike
96 Carrera (soon tt)

[CamB]

Be careful. Last time I read about this, the best way to get sufficient strength in the rear to mount the coil-overs was to tie in the shock towers to a roll cage:

G50 in 911 conversion question

However, you could try and replicate whatever the 964/993 use (I've never looked, so I have absolutely no idea...)

These guys oughta know:

http://www.racersgroup.com/911%20suspension.html