bader$

Mine are 26mm front and 16mm rear i think. Why do you have to upgrade the caster blocks?

Steve PH

That was how I read it too, you re-index the torsion bars so that the car sits low/ rides softly to start with. The new coil overs should then take up the slack and provide easy (in comparison) ride height adjustment.

Scootin159

Thanks.

joseph mitro

when i saw the price for the bilstein escort cup setup, i almost fainted. i spent nearly that much on separate koni coilovers for the front and KLA coilovers for the rear. i would love to have that setup!!

to answer your question - it's much easier (and cheaper) to upgrade the sway bars first and do springs/coilovers later. also, you can adjust for over/understeer using the rear sway bar and tire pressures. however, if your shocks are shot now, might as well go all the way and do the coilovers first.

you could consider (as i am) going to a straight coilover setup in the rear and eliminating the torsion bars altogether. i am told you would definitely need the delrin bushings for added stability.

edit - bader$ - i have the upgraded 968 caster blocks - less rubber compared to original

Scootin159

You don't if you're keeping 15" or 16" wheels, but it is strongly reccomended for going with 17" wheels (Porsche reccomends this, plus it will improve your ride quality).

Oh, anyways, the reason for the upgrade is the 968 units are substantially stronger units & the added forces of 17" wheels do nasty things to stock caster blocks.

tifosiman

150lb springs on the coilovers in the rear, in addition to the t-bars, will not get you a 300lb effective rate. The effective rate of the springs on the coil-overs is not a 100% relationship, it is somewhere between 60% and 75% depending on whom you speak with. This is due to the placement in relation to the moment arm. I am personally inclined to believe it is around the 60% rate due to trial and error with balancing out the handling of my car and trying various spring rates. (my opinion only, others may be a little bit different in their estimate)Thie means that if you want to acheive an effective 300lb rate in the rear, you really need somewhere around 250lb rear coilover springs.

I mentioned the pre-load because it is necessary to keep the springs from clanging around on their perches everytime you unload an inside wheel on a bumpy corner. I'd try to shoot for about an inch of pre-load at your preferred final suspension height setting.

Once you get everything set, you could tweek the height of the rear of the car *slightly* with the coilovers (for corner balancing and levelling purposes), but any change of more than fractions of an inch should be acheived by re-indexing, IMHO.

In reality, how many times, once you get it all set up perfect, would you really need/want to raise or lower the car? Probably never.

bader$

[QUOTE=joseph mitro]when i saw the price for the bilstein escort cup setup, i almost fainted. i spent nearly that much on separate koni coilovers for the front and KLA coilovers for the rear. i would love to have that setup!!

Who sells this ?

joseph mitro

paragon products sells the escort cup setup

Scootin159

Thanks for the heads up on the 60% efficency of the coilovers.

You could address the issue of preload with some helper springs though right? They're only like $10/each, so it shouldn't be too big a deal to put some on there (just need some type of ring to go between the main spring & the helper spring). Obviously I'd still want some pre-load though (don't want the spring rate changing every time I get any body roll), just I may be able to go without a full 1" .

but, basically you're saying to save the $$ & go with just tbars as there's no real benefit to coilovers? I don't plan on changing the ride height very frequently (or as you mentioned at all), but do like the idea of having some ride height adjustment. I guess if it's less than 3/4" in ride height adjustment I could do it with the ecentric bolt anyways.

pete944

Joseph said it on the 968 caster blocks. Much less rubber = less deflection. They are cheap and easy to replace. You will need an alignment after you're all done anyway so you should replace them while you're in there.

Fishey

Scootin 159

The biggest advantage of the rear coilover+dtock T-bars is that it would be much easier to change your spring rates. Then again how often will you change that unless you are racing every weekend?

Also to add to what pete said about the casterblocks most of the time the original ones need replacement as they are prone to failure.

tifosiman

The issue with the additionof helper springs on the coil-overs is that you will still see an increase in ride height in the rear. The rear t-bars just really need to be re-indexed to do it right. You can try to do it without re-indexing, but you will notice a ride height increase.

I personally chose to go with coil-overs for the ability to mess around with spring rates and get things the way I want them to be (my car is always a development vehicle and thus rarely is ever the same). FWIW, I have had 140lb, 150lb, 200lb, 300lb, and finally 400lb rear springs on there. I *may* be finally at the correct spring rates for my application, but you never know. Changing out t-bars everytime I wanted to see a change would have sucked the big one. Again, this is just me, most people would just go with a slightly larger t-bar leave things alone. Keep in mind the following two things, though:

1. The factory used the rear coil-over/t-bar set up on the cup cars.
2. There is a limit to the diameter available in t-bars.

Good luck!

Fishey

Tifo do you know what torsionbars the cupcars ran?
Also what was the rule on springrates for the coilovers on the rear?

tifosiman

From the documentation that I have found, they ran re-indexed 23.5mm rear t-bars with the following:

Inconstant-wire-diameter, conically shaped, progressive-rate (160 to 410lb/in) Turbo Cup springs on the front. (These utilized the stock-configuration spring perches)

Inconstant-wire-diameter, cylindrical, progressive-rate, 2.25 inch internal diameter, Turbo Cup springs on the rear. Most sources suggest these springs have a rate of 140 to 405lb/in.

Fishey

So, they might have been useing the coilovers as a way to easily adjust like we mentioned before?