TexasGunRunner

I've read some of the threads on suspension about cutting coils, upgrading coils, coil-overs, etc.

In one thread, a number of people argued that coil-overs weren't worth the expense, and in another thread a week later there was nothing but praise for it.

In speaking to a non-rotor autoXer friend (he has a highly modified and lowered 2000 Audi TT), he told me I"I must have them." He said coil overs meant "coils over the shocks" in front. I told him I already had that and I showed him the diagram of stock suspension from the '85 FSM. He, of course, pointed out that with coil-overs you could adjust it.

So, the only gen I coil-over kit I've seen links to is the ground-control setup. Very expensive, and requires specific springs, correct?

Do I understand that really the only difference between the upgrades (Racing Beat, Suspension Techniques, etc.) and the coil over kit (requires Eibach springs?) is that they are adjustable?

Wouldn't going with the progressive springs of Suspension Techniques achieve much of the same, at significantly less cost and effort? I mean, if I understand that correctly, the spring acts stiffer under compression, therefore it acts stiffer under hard cornering, when you want stiffer springs.

Also, how do the coil overs allow you to drop more, if the 1" limit is imposed by the issue of bottoming out the suspension? Wouldn't you have to extend the stock towers even with the coil overs to get more than a 1" drop?

I would appreciate any knowlegeable person helping me to understand this from the basics up.

Thanks,
Brian T. C

Re-Speed.com

iTrader: (3)

A true coil over set up is used for a number of reasons. First, it will allow you to run a industry standard aftermarket spring (i.e..2.5"). These springs come in way more pound rate options than are available as direct replacements for your car, this allows you to tune your handling. Second, they are smaller in diameter. This will allow you more clearance for tires under the fender. They also allow more clearance inside the shock tower of the vehicle shell. This will allow you to run more negative camber. Third, they are adjustable by means of a threaded spring base. This will allow you to adjust you ride height but more importantly you will be able to corner weight your vehicle to obtain equal wheel rates.

Also true would be to convert your rear springs if your rules allow. This will allow you the spring options and allow you to corner weight the whole car. You will need camber plates up front to take advantage of the new clearance. Ideally you would also want adjustable end links on your sway bars to adjust out any pre load on the bars.

The first gen race cars I have built all used shorter than stock shock inserts. This allowed me to remove approximately 2" out of the strut housing to keep the shock from bottoming out under bump travel after the car was lowered more than 1".

hope this helps.
-billy

JIMMY54

iTrader: (2)

That's the groundcontrol coilovers on my first gen,

The springs come with the kit. and you have a rear coil over kit also but it requires abit more custom work.

adjustability has been usefully lately with getting the car on the dyno and onto hoists.

However you can't bring the suspension all the way down without getting wheel spacers of have rims with a large offset.

On mine I have it set up so there is half an inch between the tire and fender.

TexasGunRunner

OK, so if I understand correctly, a real coil-over isn't just adjustable, it is also gives you more options for doing other things (greater flexibility/scalability).

It also seems like it is a whole other level, in that you would have to know and understand what you were doing in setting the height, choosing specific spring rates, and setting the camber.

I am curious, how many people on the forum and running aftermarket springs, progressive springs, or coil-overs, and how many with the coil overs are using it (i.e. adding camber plates, etc.)?

To be honest, I will probably have to be bitten by the AutoX bug before I will want to go to that level.

Thanks for explaining it to both of you, and thanks for the on-board photo Jimmy.

Regarding the spacers for the wheels - that brings up another question. My Audi TT friend uses spacers, they are very common in Europe (he bought the car in Europe, but it is a NorAm config). He wanted to get slightly bigger spacers and was told by Discount Tire (massive US tire chain) that they would not sell them to him or mount them for him. They also said they doubted anybody else would due to liability and safety concerns.

Is that just because we are so litigious, or are US spacers just that poorly made?

TexasGunRunner

One other question - is ground-control the only one that makes a coil-over kit for the Gen I RX-7?

nosajwrx-7

MazdaTrix sells the adjustable perches and I assume the top plates. Not sure if the springs are sold separately, or come with it. G-force also sells a the same and you do have to buy the springs separately. I think Ground Controls kit is the least costly. That is what I have on my car. You should look into buying the Book "Tri Link" from G-force. It is a great informational asset for setting up a 1st gen to handle.