GT4 Race Car - QA1 Issues Advice Needed

(Note: all suspension references below are for the QA1 shock upgrade, so no reference is made to any other shock, including the original Konis. Also, this a track-only car that will be set up vintage racing. And it's a GT4, not a GTB/GTS.)

Ok, so I did the QA1 set up exactly as described in the seemingly 1001 posts here, and also detailed specifically in Verrell's booklet on the suspension upgrade, last edited in 2014.

I used the longer rear QA1 shock that has been referenced specifically as a way to use a longer shock as opposed to using the GTB QA1 shock with using the extension. And "extension" does not mean the Verrell part for the front shock that eliminates the need to chop a V in the A-Arm, I'm referring to an upper eye-bolt extension that adds an inch to overall shock length.

Part Numbers:

Front QA1 shock (GTB/GTS/GT4): HAL-DS402
Rear QA1 shock (GT4 only): HAL-DS602

Front Spring Eibach: EIB-1000-2500-400 (10")
Rear Spring Eibach: EIB-1200-2500-350 (12")

I used for reference the 350/400 track only recommendation in Verrell's booklet and in other individual FC posts.

I also did all the suspension bushings and the thicker rear sway bar (both parts from Superformance UK.

A key issue is the ride height in the rear. The ride height was adjusted at the lowest point where the spring has some load on it when on the lift, but, when taken off the lift, the ride height is very high. Confusing the issue was a discussion with someone at QA1 who said the HAL-DS602 is designed for a 14" spring! He claims the longer spring would allow the ride height to lowered with the spring tension "corrected" by the extra length (a little counterintuitive, but I understand the logic).

Here's the problem…in all the posts about the QA1 upgrade I can't see any reference (or debate) about using a 14" spring in the rear! Nor have I seen a post where someone has put these shock in a GT4 and said they can't make the ride height lower. I saw a post where someone specifically references having 11 threads showing on the bottom of the shock - you can see in my photo that I have a lot more than 11 threads!.

But, maybe my mechanic (someone well-versed in Ferrari 308's but not as much with aftermarket parts and race prep).

But…does it matter if the shock spring is "loose" when the rear end in up on jacks? When the car is off the lift and on the ground, the shocks will simply be pressed into the upper housing by the load – and it seems like it would take a lot of force (or the worst possible combination of a sharp turn angle and a big bump in the road) to pop the spring off the shock. Eibach actually makes a "helper spring" that consists of a very soft spring that you place on top of the actual spring (along with a and it acts as a spring tightener when the shock is unloaded. And…. I've never seen a post where anyone has ever mentioned using these. My old 914 race car had springs that popped out of the top shock housing and the mechanic just put a zip tie on it! (...no duct tape was available..)

Another thing – if the GT4 indeed requires a 1" longer shock, would that not also effect the length of the spring that should be used? The Eibach spring part number above is the same part used for the shorter GTB/GTS QA1 shock.

Also, in some of the posts, there seems to be some contradictory information about the need for a longer rear shock on the GT4 (either the DS602 shock or the shorter GTB/GTS shock with the extender), so I'm not fully clear if the longer shock is even the right the way to go. (But –*80% of the info seems to support the need for the longer rear shock on the GT4 because they stock shocks are 1" longer than the GTB/S.) (Which a couple experienced Ferrari mechanics told me was not the case…which makes all this more confusing.)

So – advice, please! I'm on a crazy deadline to get the car ready to be picked up for transport to Monterey on the 10th! Maybe one of the issues is that there are far fewer GT4's being modified with the QA1's (vs. the GTB/S), so the advice circle is pretty small, so getting feedback from another GT4 QA1 guy is not as easy as a GTB/S QA1 guy.

Anyway, sorry it's so long...
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And, by the way, both Birman and Verrell happened to be on vacation!!

 

Thanks BBB, I'll let you know. LD, I have a garage too. I wonder if you can ask to be roomies? It's looking good that I'll make deadline. My fab guy can't do his stuff until Tuesday, and I don't have tires yet - but I'm going to try to go to a Willow on Sunday and do a "pre-test" on one of the small tracks there (dirt track!). This way, I can at least get the car running at some speed and see what's up. And it won't matter as much that there are new - but 13 years old tires on it! And do a general nut and bolt check and oil change. This would allow me at at least see if the Elecromotive and the carbs are working at speed. And then maybe go back on Friday at the big track. I was there yesterday testing my Reunion car - it was about 7000 degrees! Or BBB, if you know of a really big parking lot in town... (Car us not street legal.)