Hydraulic Throwout Bearing - No Clearance

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Old Apr 25, 2016 | 05:35 PM
  #1  
Delmont 88 PA's Avatar
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Hydraulic Throwout Bearing - No Clearance

I'm converting my '67 Delmont 88 4 speed to a hydraulic throwout bearing. Ram calls for 0.180" clearance. I have approximately 0.030" interference with no shims.

It's a Saginaw 4 speed with a new (from NAPA) clutch and pressure plate (10.5"). The flywheel is after market and I'm not sure if it's thicker than stock (this would put the pressure plate farther away for the engine).

I emailed Ram and have not got a response so far. I couldn't find info on what the installed height of a GM pressure plate should be so I don't know if buying another pressure plate would help. Also, a thicker clutch disc should bring the pressure plate fingers in but, again, I'm not sure what clutch disc that would be.

My ideas are:
1. Fabricate an aluminum spacer plate between the bellhousing and trans.
2. See what I can cut from the flywheel.

Any ideas?

Thanks,
Chris
Old Apr 25, 2016 | 07:03 PM
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First I would check and make sure there is no load on the MC from the pedal. Second, I'm thinking a spacer but I would wait to hear from Ram. I would not under any circumstances cut the flywheel.
Old Apr 25, 2016 | 07:54 PM
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I agree on waiting to hear back. You need the room to account for clutch wear.
Old Apr 26, 2016 | 03:50 PM
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Delmont 88 PA's Avatar
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Thanks for the responses.

The master cylinder is not connected yet.

Ram got back to me and recommended cutting the bearing retainer where the throwout bearing mates. He said that he had good luck doing that and it's easier and won't create possible issues that a shim plate could cause.

Thanks again and I'll post when it's all done.
Old Apr 26, 2016 | 04:02 PM
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Glad you have a direction to correct your issue.
Old May 9, 2016 | 04:55 PM
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The throwout bearing is installed and has clearance. We had to fabricate a plate to install between the trans and bell. Ram recommended cutting the bearing retainer but there wasn't enough material. We also found out that the splines would have interfered with the Mondello pilot bearing (which did fail in the original installation).

Everything is together and the clutch works; however, there is a lot of flexing of the firewall where the master cylinder is mounted and the next step is to make a plate to beef up the firewall.

Maybe this weekend I'll have a car to drive....




Fabricated plate between trans and bell






Plate on trans
Old May 9, 2016 | 05:48 PM
  #7  
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I had an aftermarket pilot bearing that came with no instructions. It should have said to drive the bearing in as far as possible, and should have showed an illustration. It caused the engine thrust bearing to fail.
Old May 9, 2016 | 07:22 PM
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Making a doubler plate for mounting the M/C will work. Hopefully it has an adjustable actuator rod.
Old May 10, 2016 | 04:31 PM
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This was a Mondello throwout bearing that fits in the recess for the snout on the torque converter--since it was originally an automatic it wasn't drilled. It was driven in as far as it would go. Good point though--I'm glad that the bearing came apart rather than the thrust bearing failing.

The is adjustment on the M/C rod and as you state above, "There is nothing that can't be solved with a suitable amount of explosives!" We're getting close to that....
Old May 10, 2016 | 04:37 PM
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PFFFt, you'll get it. Post some pictures of the setup when you get a chance.
Old May 18, 2016 | 04:16 PM
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Shown below is a picture of the cardboard template we made (the master cylinder is not mounted but setting there sideways and out of the way and the finished installation (0.100" sheet metal painted red).

The kit that Jegs sold me has a 7/8" diameter piston in the M/C and it calls for 3/4" maximum. I'm a big guy and need a good breakfast and a tailwind to depress the clutch pedal. Ram technical said that as small as a 5/8" diameter M/C will work if I have the travel--which I do. Jegs is making good and sending a 5/8" M/C. This should reduce pedal effort significantly.

I'll let you guys know how it works when it gets here.

My father-in-law is a retired body shop owner and has built many custom cars and trucks. Thanks to him for designing the patch. I did the dumb work--cutting and painting.



Old May 18, 2016 | 04:35 PM
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Whats it look like at the trans? Nice work up top.
Old Jun 10, 2016 | 03:29 PM
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This is a picture of the hydraulic lines running through the shift fork boot.

The car is finally streetable. The good news is that the clutch pedal is easy with the 5/8" diameter master cylinder. The bad news is that the clutch barely disengages. I could pull the tranny and install another shim on the pilot bearing but I'm trying to drive it for awhile and see if it gets better when the "fuzz" wears off the new clutch disc.
Tomorrow I will be making the 55 mile trip from my father-in-laws garage to my house. I put a few miles on it last weekend and the clutch is a pleasure to use compared to how it was with the clutch arm and slave cylinder....
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