Dual clutch shudder - first gear from start - SUH

Good Morning,
This is my first foray into the clutch ('89 Mondial t - 36k miles - original clutch). First gear takeoff has a significant shudder 8 out of 10 times (worse when fully warmed up) unless I start very, very slowly with lots of clutch modulation. The triple seals were leaking, so I replaced with the assist of forum posts. I clean all the components with brake cleaner (assuming it was oil contamination causing the problem) and reassembled, but the condition remained. No other symptoms, no throwout bearing rattle.

I pulled the pumpkin again - no signs of leakage and wanted to check the set up height and measure plate thicknesses - found all the dimensions, but couldn't find the checking procedure in the forum for set up height (47-51 mm). Can anyone point me to the procedure? Thanks in advance.

 

Wade,
Thanks for getting back to me so quickly! I had looked at those references earlier and have the specs, but not the measuring procedure. I did make an attempt to measure using a reference point (top of a 2-foot level across the top of the clutch and measured down to the two points) and the compressed thickness of the driven plates using various size allen wrenches - +/- 0.25 mm accuracy.


The Ricambia link didn't work for me I think this is the updated link
https://www.ricambiamerica.com/car-diagrams/ferrari/v6-v8/348-group/348-1989-1992/clutch-controls.html
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Does this procedure make sense? Subtracting the two measurements for the SUH I got 50 mm.
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Ferrarium,
Yes, that should do the $$$$ trick! I'm looking for a cheaper solution first.

Wade,
I searched, but couldn't find anything that addresses the process in detail - so for now I'm using my approach - hopefully not missing something. Since my measured/calculated number was 49 mm and the range is 47-51 mm then I'm in the ballpark. I guess if your stack too short then you'd add shims, too tall and you'd have to remove shims or mill the intermediate plate?

I tend to think it's an issue with oil contaminated friction plates - interesting when I measured the uncompressed thickness that the flywheel side plate averaged 7.37 mm and the bearing side was 7.22 - the "new" spec is only 7.25 mm and clearly there is wear, so perhaps oil/oxidation has caused them to swell? When I attempted to measure compressed thickness the flywheel side plate was only 5.5 mm, which was below the spec of 6.10.

You mentioned the possibility of plates being "rotated a few degrees." Are the friction plates supposed to be in some sort of rotational alignment other than just the splines lining up?

 

Thanks

1. Yes - leaning towards the oil contamination cause

2. I don't believe they were skimmed, but have no history and I've had the car for three years - also a possibility as you mentioned.

 

Problem Fixed.

I had tried cleaning the discs with brake cleaner and reassembled - the test drive showed no improvement after the car was warmed up - still shuddering with first gear start, so back apart.

I was out of town for three weeks, but decided to send the discs out for relining to ALL FRICTIONS CO. (Tim Doran) PORTLAND, CT, 860-342-2001
[email protected]. Tim confirmed oil contamination, but noted very little actual wear. I got them back in a week, but couldn't install until yesterday. In addition to the new lining the frames were bead blasted and painted. They stamped a "B" on the bearing side disc and "F" on the flywheel side disc. The cost was $198 (organic material) total for both including shipping.

I had also noted during the disassembly/reassembly that there are a lot of metal to metal contact surfaces that clearly have to be clean and smooth for the plates to move. there was surface oxidation and wear marks that I cleaned carefully with a scotch brite pad and brake cleaner. During reassembly I applied a very THIN film (more like residue) of copper grease to the contact points to make sure there was no binding of the assembly in operation.

I bolted the clutch assembly back together and took the car for a test drive - shudder was gone, engagement smooth and positive and no evidence of slipping. I believe the oil contaminated clutch disc linings represented the majority of the problem, but wouldn't rule out binding assembly as a contributing factor.

Pictures of New/Old discs...


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I provided them with the spec thickness, but of course they measured the clutches I sent. As I noted I had very little wear on mine, but they were oil contaminated.