Fredman6

Hello, have a ‘22 718 GT4. Getting corner balance and track alignment done next week. After reading recommendations at https://rennlist.com/forums/gt4-spyd...etup-wiki.html
I’m shooting for:-2.7 to -3 Front Camber with 0 Toe, -2.3 to -2.6 Rear Camber with 3mm Toe In. Appears best to keep rear camber 0.5 less than front?

Car will be used 90% on track and AX. I have the front adjustable thrust bearing for correcting caster and the rear toe links with lockouts.

What ride height and rake is recommended? I want aggressive for track, want to reduce stock understeer but I do not want any tire rubbing.

Thanks, Fred.

edub

Tire rubbing can happen on the stock springs, I'm not aware of anyone explicitly 'solving' for that but I'll follow the thread to see if anyone chimes in.

I have a one degree less in the rear while running -3degree in the front. For track I have very even tire wear, but I don't have tire temps to share.

As for ride heights - I haven't seen an actual data sheet for a 718 GT4, but piecing together information from forum posts I have the following notes for now

Front 109mm +2/-0mm. Measured from ground to measuring point on the cross member

Rear 130mm 2/-0mm. Measured from ground to measuring point on diagonal brace



Notice the ride height variance front rear and left right.

Measuring ride height the factory way is difficult, as the measuring points are not under a typical lift and the measuring datum needs to be set up. You'll find a lot of people just go with the fender heights. I can share what worked well for me while using 20" cup2's.
26 1/8" FL, 26 1/4" FR
27 1/8" RL, 27 1/4" RR

You can see its about 1" of rake in terms of ride heights from the fender.

edub

Front measuring point, it's near the front wheel brake duct. I don't have the rear photographed.

Fredman6

Thanks. I too found the 109F/130R factory specs. Was curious if there’s benefit to lowering ride height or not. Appreciate your feedback.

edub

Dunno, I haven't done the measurements to figure out what the difference would be to lateral load transfer. With a move to 19" or 18" you are in effect lowering the ride height, maybe some folks who run those sizes can explain their perceived differences if any.

lovetoturn

Not much benefit in lowering the car except increased risk of blowing out a front shock tower.

voods

I have this setup, except with front toe out as well. Car came with some random garbage rake and ride height from factory. I set the 981 rake/heights from the pdf above and it was so much better, killed off a lot of understeer. I wouldn't lower beyond 109mm front on stock shocks because of strut top mounts being weak.

edub

Yeh I'm curious about this one, the MR setup drops the front 16mm below the factory ride height (109mm) but you said that was measured on hubstands. I don't see why hubstands would be any different than the actual ride height, it kinda flys in the face of using hubstands if you don't measure off what would be the ground and relative ride height.

Either way though, the rake is the rake. Seems more is better, I'd be keen to test that in a meaningful way. I'll have to see how I could manage doing that at the track one day.

sgreer78

It doesn't matter what the number is as long as it's consistent. They know what the hub stand height is relative to the actual wheel-on height.

edub

Anyone have a photo of the rear ride height measuring point. I see the image in the manual but without a lift, I can't really see what the heck is going on down there

sgreer78

The black line is the OEM measuring point.

edub

Ugh - why don't they have a service hole to measure here.

sgreer78

I thought the same thing. It was much easier on the 981. I supposed to you get a measurement with it on and off and figure out the difference then use that for future measuring.

edub

During an alignment today I measured the fender heights and front ride height.

The rear ride height I'm not sure about...its well below spec. I foolishly didn't snap a photo of where I measured from, but I had the presence of mind to mark it with a pen. Well at least I'll know where my mistake was if I made it.

I also took a measurement from a always exposed portion of the rear subframe for future reference.

2021 718 GT4

245/35ZR-20 CONTINENTAL EXTREMECONTACT DWS 06 PLUS XL @ 30.5 psi

295/30ZR-20 CONTINENTAL EXTREMECONTACT DWS 06 PLUS XL @ 32 psi

Front ride height - 93mm (LOLOLOLOL)
Rear ride height 104mm (left) 105mm (right). I think I measured from the wrong spot on the subframe, how could it be 26mm below factory spec?

Fender ride heights
664mm Front Left (26" 1/8), 667mm Front Right (26" 1/4)
676mm Rear Left (26" 5/8), 679mm Right Rear (26" 3/4)

(my metric to inch conversion is for convenience, actual conversion should be in 64th of inch)Pictured is the rear ride height location I "added" since the subframe is usually covered. This distance to ground is 86mm (left) and 88mm (right). I realize these numbers are meaningless to others without knowing the tire height. Welp, thats life.


If my rear subframe measurement was actually from the right spot, I'll probably raise the rear for more rake. Hopefully I just measured wrong.

edub

In the paddock today, I wandered around and measured stock GT4's on 20" Cup2 tires.

the two cars I found had the following values. Granted, unknown fuel and luggage, not level ground.

Car 1 - ground to fender height
695mm front
700mm rear


Car 2 - ground to fender height
689mm front
705mm rear