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Old 06-03-2018, 10:58 PM   #1
billrobbobjo
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LQ4 w/ LS Luk Clutch, wont disengage

Hi, I have just put a LQ4 in my 57. I was planning on running a manual trans so i bought a ls1 clutch set up for it. Currently im just trying to get it running w/ my old running gear which was a T5 that was on my 235 before. Long story short, I get it all together w/ the new fly wheel w/ matching pressureplate with the T5 10 spline clutch disc in the middle. I adjust the linkage so its where i believe it should be almost tight at the top of the pedal. Only problem being I cannot get the clutch to disengage as I push the pedal down. I havent ran the truck yet but i thought i should be able to spin the yoke on the output shaft by hand w/ the clutch in like as if it was in neutral. Currently everything feels/ seems correct but I dont seem to have any luck of spinning the yoke. Is the pressureplate for an LS alot harder to push or does the hydraulic one move farther than the older style throw out bearing? i believe the fork should be able to handle the pressure, I have even tried using a comealong to move the fork back far enough and I cannot get it to spin with 2 people trying to spin the driveshaft.

I also have tried losing the bolts on the tranny to make sure that the splines on the input shaft were not driving the disc into the back of the fly wheel.

Any ideas? The T5 clutch disc is about 1/4 inch. The LS 26 spline disc is closer to 3/8 to 1/2 inch thick. My only last idea is that the clutch fingers have to move farther being that the disc is smaller in width because the pressureplate might need so much preload or something?
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Old 06-05-2018, 03:39 PM   #2
Wrenchbender Ret
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Re: LQ4 w/ LS Luk Clutch, wont disengage

If you have a cover over the bottom of the housing, prop the clutch pedal down & see if the pressure plate moves back enough to leave a gap between the lining & the plate & flywheel. You may just have a drag on the pilot bushing that will clear out when you get it started.
You can't put a preload on the clutch. You will destroy the TO brg &/or the main brg in the engine.
George
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Old 06-07-2018, 01:07 PM   #3
mr48chev
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Re: LQ4 w/ LS Luk Clutch, wont disengage

You did put the disk in with the raised portion for the springs to the back? There have been cases where guys have put the disk in backwards and it won't release because it is catching on the heads of the flywheel bolts.

I agree with wrechbender as I usually do in that you don't even want to "preload" the clutch as that will eat up release bearing and disk.

If you have the cast bellhousing with the cover on the bottom I would first do as he suggested and get under the truck and watch while a helper pushed the pedal. The pressure plate should release and you should be able to reach up with a screw driver and turn the disk with the trans in neutral. I it doesn't turn with the pressure plate released you might slip it back a bit with the screw driver and see if it will turn then.

If the disk is still hanging up when you can see that there is space between it and the pressure plate you could take the bolts out of the pressure plate (maybe sticking a couple of longer bolts in place to slide it back on so you could look up inside and make sure it is oriented right before taking the whole thing apart.

I've replaced at one clutch disk that someone else replaced that had the hub bent because the guy who installed it let the weight of the trans hang on the splines of the disk/input shaft while installing it. That one wouldn't release all the way.
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Old 06-16-2018, 11:31 PM   #4
billrobbobjo
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Re: LQ4 w/ LS Luk Clutch, wont disengage

I switched to a NV3500 clutch disc and fly wheel w/ matching pressureplate.
Problem solved. The pressureplate i was using had 2 diaphragms in it and the throw out bearing wasnt engaging the second one.

Thanks for the help guys! Off to the next problem, Tuning the LQ4....
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