TR-3650 proper spec for throwout bearing

TheCrowdPlow

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Ive had a hard time finding a solid answer for the proper spec for the throwout bearing "preload" on a TR-3650. I did my measurements and from engine block to pp fingers is 2.95". and from bellhousing to top of throwout bearing with the throwout bearing fully compressed is 4.14". Throwout bearing can extend 1.46". Im pretty sure I need .5" of travel movement for the throwout bearing. So I need to shim the throwout bearing correct? Ive got 2 .17" spacers on hand but am skeptical of stacking 2 on top of each other cause the throwout bearing locates onto a flange on the bellhousing to prevent it from moving side to side. Or is that a non-issue?
 

Midlife Crises

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Trying to figure out your numbers, I come up with from the bell house to throwout bearing is 3.68” and from the engine block to the PP fingers is 2.95”. That is 0.73” preload and should work. I would add a 1/4” spacer myself to be closer to 1” preload. Don’t forget to use longer bolts to mount the throwout if you add shims.
 

TheCrowdPlow

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Trying to figure out your numbers, I come up with from the bell house to throwout bearing is 3.68” and from the engine block to the PP fingers is 2.95”. That is 0.73” preload and should work. I would add a 1/4” spacer myself to be closer to 1” preload. Don’t forget to use longer bolts to mount the throwout if you add shims.
Isnt it 2.68" from bellhousing to throwout bearing? 4.14-1.46=2.68. If it was 3.68" wouldnt the throwout bearing not contact the fingers on the pp because block to fingers is 2.95"?
 

Midlife Crises

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wouldnt the throwout bearing not contact the fingers
The throwout bearing With its light spring pressure is supposed to ride on the pressure plate fingers. There is no “gap” or free play allowed.
See what I mean, trying to think backwards. Just measure from the block to the PP fingers and from the bell house flange to the throwout bearing as it is mounted. Don’t compress anything. You want near 1” interference.
 
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TheCrowdPlow

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The throwout bearing With its light spring pressure is supposed to ride on the pressure plate fingers. There is no “gap” or free play allowed.
See what I mean, trying to think backwards. Just measure from the block to the PP fingers and from the bell house flange to the throwout bearing as it is mounted. Don’t compress anything. You want near 1” interference.
Yes I know its supposed to contact the fingers, I just was using your numbers and wouldnt your 3.68" number mean that the throwout bearing would have .73" of gap between it and the fingers?

So 1 inch of compression of the throwout bearing is the go to? Does it work where the closer I am to 0" of compression the clutch will start disengaging closer to the floor? and Vice Versa?
 

TheCrowdPlow

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bell house flange to the throwout bearing as it is mounted. Don’t compress anything. You want near 1” interference.
that measurement without any spacer is 2.68". so 2.95-2.68=.27, only 1/4" of compression, so wouldnt that mean i need about a 3/4" spacer for it to be about 1" of compression?
 

Midlife Crises

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that measurement without any spacer is 2.68". so 2.95-2.68=.27, only 1/4" of compression, so wouldnt that mean i need about a 3/4" spacer for it to be about 1" of compression?
Yes. That is what it means. I believe you can get by with 3/4” preload so a 1/2” spacer would do the job.
 

TheCrowdPlow

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Yes. That is what it means. I believe you can get by with 3/4” preload so a 1/2” spacer would do the job.
Thats kinda what I figured but wanted to make sure that what Im doing is correct. What about my other 2 questions?
Do I need a kind of spacer so that it locates the throwout bearing perfectly centered on the shaft or do plain flat spacers work with no issues?
And does have the amount of preload on the throwout bearing affect where the clutch engages and disengages at the pedel?
 

Midlife Crises

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fits perfectly
Yes, the spacer I purchased (from Summit) is machined on both sides to fit. It works on the 3650 and 6060 type transmissions. Fits the GM models also. As far as clutch pedal position, what I found was when I had less than 1/2” preload I had to push the pedal to the floor. Makes sense because the throwout it at the end of its travel. When I shined it to 1” preload I do not have to put the pedal on the floorboard to shift. It did raise the working zone of the pedal a little bit. You will not really gain travel because it is hydraulic and the master only pumps X amount of fluid.
 

AutoXRacer

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What made you research spacers for the throwout bearing?

Just curious as I'm running a T-56M XL with McLeod twin disc clutch and OEM throwout with no spacers.
 

Midlife Crises

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What made you research spacers for the throwout bearing?

Just curious as I'm running a T-56M XL with McLeod twin disc clutch and OEM throwout with no spacers.
I was running a McLeod street extreme clutch with McLeod OEM style throwout and a T56 Mag and a McLeod light weight steel flywheel. It stacked up with 7/16” preload. I had to push the clutch pedal to the floor or the clutch would drag. I could feel it when shifting. When I killed that clutch I replaced it with the RXT. It stacked up just about the same so I added a 1/2” spacer to make sure it will not drag on a speed shift.
 

Midlife Crises

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So is the McLeod OEM style throwout bearing shorter than OEM...?
No. I measured them side by side and they are exactly the same. Also measured a friends Exedy OEM replacement and it was the same length.
 

rocky61201

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What made you research spacers for the throwout bearing?

Just curious as I'm running a T-56M XL with McLeod twin disc clutch and OEM throwout with no spacers.

Aftermarket flywheel and clutch combinations are not always the exact same spec (thickness) as OEM. Sometime you needs a spacer a two. I had to install 2 spacers with my setup. Been working great for a couple years now I think.
 

Rick Simons

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The finger height will vary between clutches, but the release bearing preload is CRITICAL! If the bearing travels too far it can push it past the crimped edge of the inner sleeve that it rides on, causing it at best to leak and at worst, well, use your imagination.
With an Exedy Mach 400 I set mine up with 24mm preload using a .375" spacer. The Hays 82-116 spacer I bought was nothing fancy- didn't have any alignment features other than the bolt holes (could have built the same thing at home with a lathe or a couple of hole saws) so I just eye-ball centered the release bearing. The bearing is built such that it will center itself if it's a little off.
 

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