wt. of coil-overs

Randy Webb · 08-31-2003, 08:26 PM

Does anybody know how much wt. would be saved in the rear by using coil-overs instead of the stock torsion bars?

dean · 09-01-2003, 05:40 AM

I don't think you would reduce the weight by very much. I would guess no more that 20 lbs. But I don't know. I think you would loose the most weight in your wallet

I would lilke to got to rear coilovers in my car so I can move the povertrain forward some. But that mod is a few years away.

09-01-2003, 06:01 AM

from Calzia's chart:

Front Suspension Assembly

Steel cross member, 2xA arms, 2x23 mm solid torsion bars, 2x Boge struts w/ Koni inserts, 2xiron rotors, 2xaluminum hats, all wheel bearings
98 lbs
ERP Al cross member, 2x935-style A arms, 2xBilstein RSR struts, 2x350 lb/in springs, 2xAl rotors, 2xAl hats, all wheel bearings
71 lbs

Rear Suspension Assembly

2x29 mm torsion bars, 2xadjustable spring plates, 2xaluminum bananas, 2xKoni shocks, 2xiron rotors, all wheel bearings and stub axles (inner and outer) 2xERP spring plates, 2xaluminum bananas, 2xcoil-over Koni shocks, 2x500 lb/in coil springs, 2xaluminum rotors, all wheel bearings and sub axles (inner and outer)
110 lbs
2xERP spring plates, 2xaluminum bananas, 2xcoil-over Koni shocks, 2x500 lb/in coil springs, 2xaluminum rotors, all wheel bearings and stub axles (inner and outer)
77 lbs

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Randy Webb · 09-01-2003, 11:49 AM

Thx -- I should have remembered and looked that up for myself.

Chuck Moreland · 09-01-2003, 12:23 PM

Unfortunately the weight of the coils gots lost in the table mix. I expect a great deal of the front wt savings is from AL rotors and ERP control arms. The AL cross member saves about 15 lbs all by itself. In the rear you've got AL rotors and ERP spring plates, both saving a good bit of wt.

A solid 29mm tbar weighs about 8.5 lbs. A hollow 29 weighs about 6.5 lbs. So the potential savings using coils is something less than that. Don't forget to add in the weight of the spring perches.

jluetjen · jluetjen's Garage

You also need to add half of the coil's weight to the Unsprung weight of the car on each corner. Unsprung weight is EVIL. The neat thing about T-Bars is that they are entirely sprung, while only half of a coil spring on a 911 style suspension is unsprung.

So while you're reducing the overall weight of the car by some less then 18 lbs, you're adding a fairly significant amount to your unsprung. You might want to compare the overall percentage change in the car's weight versus the percentage change in the car's sprung weight.

To be honest I still don't understand the magnetic attraction to coil-overs on 911's, especially on non-competition cars.

Chuck Moreland · 09-01-2003, 03:19 PM

And those coils raise the CG, and they are further rearward than tbars.

Bill Verburg · Bill Verburg's Garage

Just as an aside the al. metal matrix rotors are an idea whose time hasn't quite arrived yet.

Chuck Moreland · 09-01-2003, 03:26 PM

Not to hijack the thread, but Bill what do you know about these? What's wrong with them, how much to the weigh, where to buy?

Bill Verburg · Bill Verburg's Garage

AFAIK they had a tendancy to overheat, and if not melt at least soften to the point of uselessness. As a result they were withdrawn from the market.