My Mantic 9000+ Twin Ceremetallic bought new and installed July 2020 started slipping perhaps 3 weeks ago. No leaks to be found.

I do not know whether my clutch kit is using sprung or unsprung discs. I thought I took photos of everything before installation but I cannot find the photos. I inferred from Geoff at Mantic that all of their disc hubs were sprung on this model? I'm not sure on the mileage, but it's been about 14K since summer of 2019 (engine rebuild) without any unusually long trips... maybe 9-10K miles on the clutch. The pedal engagement point does seem to have moved up. Once in awhile it's notchy getting it into gear from neutral.

My original 2009 Tick master had a failure around September 2021, so I had a local LS1 shop replace it. They said everything felt normal and sent me on my way. I still thought there was some sponginess in the pedal. Drove it across town a few days later and I became stranded in stop'n'go interstate traffic when the brake fluid reservoir ran empty. Same shop then replaced the slave the following week. Shop owner verbally said the pedal felt normal and I'm pretty sure the receipt said they adjusted the clutch, but I'm not convinced they measured for a spacer (provided) or did anything special with the master rod adjustment. This shop was not my preferred installer but my preference was too busy. The clutch fluid reservoir is still full. If the last slave failure was in Sept/Oct 2021, does it seem reasonable that slippage would be delayed ~6 months after clutch fluid potentially contaminated the discs?

Last night I found both locking nuts on the pedal rod to be flush with the ends of the turnbuckle and not loose. There was minor rotational play in the overall rod assembly but otherwise seemed normal. I loosened the bottom nut and began rotating the rod in the same direction to move the turnbuckle closer to the floor. So far I may have moved it a number of 1/4 turns and the engagement point seems to have moved down a bit, still getting some slippage though. What I want to know is the happy medium between making things much worse (can one damage the slave or clutch fingers if the rod is shortened too much) and attempting to correct the slippage issue without replacing parts. With the clutch currently slipping, how do I know when I'm on the verge of shortening the rod too much, and then know I need to lengthen it a bit?

If I need a new clutch, then debating on trying them again with a twin organic (since I despised the takeoff chatter) or a Monster LT1-S. I know the latter doesn't have a sprung hub and is heavier. I generally don't give a vendor a second chance if there was a premature parts failure that isn't due to human error. I basically want the OEM behavior of a LS7 clutch (that lasted me over 10 years and began slipping only after I installed the 416) with some weight/MOI savings that doesn't effect drivability or reliability.

 

After watching some YouTube videos, I've continued to slowly screw the turnbuckle clockwise (as viewed from the top). I haven't loosened the top nut, only the bottom nut, and the turnbuckle will not spin freely in my fingers, I am using an adjustable wrench to turn it. The engagement point on the pedal travel continues to move down, but I see that the bottom threaded rod portion is turning with the turnbuckle at the same time. Is that expected behavior? The slippage seems to have reduced a little in 1st or 2nd gear, anything any other gear is still slipping at low RPMs when adding throttle too quickly.

Is it safe to continue to turn the turnbuckle in the same direction until the car wants to move under it's own power in 1st gear with clutch pedal in, and revving to ~5000RPM on a level surface? Then extend the turnbuckle a little? If it still slips at the point then I'm SOL and need a new clutch (or a rebuild) I presume.

 

I haven't shortened the rod any more in the past month. Ordered a Monster LT1-S Triple clutch on May 6, they shipped it on the 16th and I delayed delivery two days so I could sign for it. Due to work projects I can't get it into the shop until June 2nd. I'm not dropping it off and have it installed unmonitored. It's about 16lbs heavier than the Mantic 9000+ Twin ceremetallic I current have installed. I took it apart and added additional alignment marks to ensure it all goes back together the way I received it. I was surprised to see that it came with the Howe throwout bearing instead of the expected OEM slave cylinder.

Mantic
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Flywheel ~15.5lbs (bath scale)
Spacers 30.34oz (avg)
Red cover: 79.2oz
Plate 1: 61.4oz
Disc 1: 45.2oz
Plate 2: 59.4oz
Disc 2: 51.0oz
Total 296.2oz
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Bolts, nuts, washers: 312.73g
Spacers+clutch+Hw=337.57oz (21.1lbs) + flywheel (15.5lbs)=36.6lbs
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Monster LT1-S Triple carbon organic
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Pressure plate (includes 3rd disc) 391oz
Outer removable disc 33.2oz
3 pressure plate stands 17.4oz total
floater plate 53.2oz
Inner removable disc 33.2oz
Flywheel 308oz
Total ~836oz=52.25lbs

 

I'll say that if the clutch worked in the past without a shim no shim would be needed after a master and slave replacement. Adjust the master and you should be fine.