Hey guys I need a little help.

I had my swap up and running, but the car would not shift at high RPMs. If I was just cruising around and shifting lightly the car would shift fine. My swap is a 5.3 with a Ram Clutch 1550 Billet steel fly wheel, ACT 6 puck sprung clutch disc, and a ACT heavy duty pressure plate. The transmission is a CD009 with a Collins Adapter plate and a T56 bell housing. The slave cylinder is a standard GM slave.

I reached out to Collins Adapters about my poor shifting issues and they suggested that I use a .050" shim to help with the release of the clutch. I have pulled the transmission in order to install a shim, and while it was out I decided to measure everything to verify the proper shim thickness.

I am using the method below to get my measurements.

For measurement A I measure from the bell housing face to the pressure plate fingers I get 2.387". I have verified this measurement probably 25 times and I am always within 1 to 2 thousandths each time. For measurement B I remove the spring from the slave cylinder, fully compress the slave cylinder, and measure from the bearing face to the mounting face of the bell housing. When I do that I get a measurement of 1.9410". I then subtract A from B and get .446". This seems crazy thick to me when the suggested shim thickness was only .050".


I welcome any help or advice anyone could offer to help me figure out what I might be doing wrong.

Thanks,
Andrew

 

Speedway Hydraulic Clutch Release Bearing Set-Up Tool Gets the bearing set up perfectly.


Measure both distances and subtract the readings. That will give you the air gap requirements. My Tilton throw out called for bearing to clutch clearance of .125” (tolerance +/-.025”) that gave a .1-.150 range. I set it at .130

 

That's the key right there. Collins didn't know what your actual measurements were. You measured and then your math says that you need quite a bit of shim thickness. My project car needed about the same thickness as your car. I measured two different ways and got gaps of .420" and .409". I used a .180" thick Tick shim and brought the gap down to .240" or .229". I should've added another shim to tighten up the gap but I didn't. My project is still not running so I can't comment on whether or not this big of a gap will work. I've been advised by a knowledgeable forum member to take it all apart and add an additional .055" shim that came in my Tick, 3-pack shim kit.

 

Thanks for the input! I have provided the updated measurements to Collins, and I am still waiting on a response. I also ordered the measurement tool that Jason recommended. I doubt it will show much of a difference from the multiple measurements I have taken with my digital calipers, but I will give it a shot and see what I come up with.

 

Following along to see what I can learn -- I don't understand these things at all....

 

I was assuming you indexed the bell housing. If that’s not correct. That will prevent clean high rpm shifts. That will also ruin your transmission bearings over time. The wrong air gap will prevent full release/stroke of the pressure plate.

 

Being a novice to this, if one was using a factory T56 bell housing would indexing still be needed? Do you need to index the bellhousing every time it comes off?

Thank you!

 

Yes you will want to make sure it stays the same once it’s indexed. Both surfaces have to be clean and no burrs or paint. Mine was at .0001 after the .007 offsets and would stay the same if I slapped the bell housing down from the top and make sure you torque it down the exact same. If I just slid the bell housing on without slapping the top down it doubled the measurements. There are some good videos online on how to index properly. The flywheel should have been checked also for runout. Indexing centers the input of the transmission to the center of the crankshaft. Here are some specs.
Standard Automotive Bellhousing Alignment Specifications:
Concentric: +/-.005” or .010” TIR Parallel: +/-.001” or .002” TIR
Hi-Performance 7,500+ RPM Bellhousing Alignment Specifications:
Concentric: +/-.0025” or .005” TIR Parallel: +/-.0005” or .001” TIR
Flywheel runout .001” to .005” Max (less is always better)

 

Sounds like, as with other things, slapping it down every chance you get is a good thing. Mine was almost perfect just bolting it on. Flywheel parallel (no picture) was even better -- 3 at zero and one at .001".

Attachment 712686

 

As has already been said, yes, you still need to index the bellhousing. I used a stock, aluminum Tremec bell and mine was off. My total indicator reading was .019" and the recommended limit is .010" TIR. Like Jason, I had to use a pair of .007" offset dowels to get my measurement within specs.

No, you shouldn't need to index every time the bell comes off. In my case with my offset dowels, as long as they're locked into position, I should be able to remove my bellhousing and reinstall it and my indexing should stay the same.

 

Andrew - I was wrong on the phone - the pic above is measuring if the tranny mount surface is parallel to the flywheel.

 

 

replacing my clutch while the motor is out for rebuilding, and noticed the plastic behind the release bearing is damaged so I wanna replace it , figure I should replace the bearing and spring diaphragm too but can’t find a part that looks like it. I am using the wildwood clutch slave. Thanks !


Is this a shim?

What parts are recommended to replace?