Topic: Clutch-Vibration


bo8109b    -- 04-14-2020 @ 1:04 PM
  '40 Sedan has always had some engine vibration but after changing out the clutch disc, vibration is serious at mid to high rpms, car stationary or moving, clutch in or out. Used same pressure plate, replacing hardware bolts with proper shoulder bolts. Probably didn't mount on flywheel with same orientation. Don't pressure plates come balanced or what's up? Carl


40 Coupe    -- 04-15-2020 @ 4:02 AM
  pressure plates do not come balanced. They can be out of balance by quite a bit.


TomO    -- 04-15-2020 @ 7:24 AM
  Both the flywheel and the pressure plate should be balanced. The flywheel should also be checked for run out as it can also cause vibration.

SHOULDER bolts are NOT used to mount the pressure plate. The bolts are 5/16"-18 x 49/64" and thread length 25/64". I used a grade 5 bolt 3/4" long with a standard 5/16" lock washer. A shoulder bolt would not secure the plate to the flywheel, it would allow some movement that could cause vibration.

Tom


bo8109b    -- 04-15-2020 @ 9:55 AM
  There is a nice picture of the bolts on Ebay at NOS Ford Flathead 1932-56 V8 special clutch pressure plate bolt set. Carl


kubes40    -- 04-15-2020 @ 4:34 PM
  I'd like to add just a bit of advice garnered from years of experience and NUMEROUS clutch assembly swaps.
When you swap the disc, replace the plate and throw out bearing ALWAYS.
Too often the restored friction from the new disc will cause the plate and / or the bearing to fail quickly.
Trying to save $60 - $75 is not worth the labor required to do this job twice. Not to me anyway.
When I had my shop in the 70's - 80's I'd refused to do a clutch job of the client wasn't willing to replace all pieces. Even though they'd get the "talk" about what might happen if all pieces weren't replaced, those that still insisted with just a new disc couldn't seem to recall the "talk" when their clutch failed soon thereafter.
Two times I went through that scenario... after that, if you wanted me to replace a clutch, it was all or nothing.

Mike "Kube" Kubarth


39 Ken    -- 04-16-2020 @ 6:20 AM
  ""When you swap the disc, replace the plate and throw out bearing ALWAYS.""

Kube, I agree with you procedure completely. I've always done almost exactly that. These day's the pressure plate "replacement" is somewhat of a cr*pshoot with all the off shore junk that's out there. I've come to the point that a rebuild of the existing pressure plate by Ft. Wayne clutch is a preferable option. Do you have any opinion re: a rebuild? As always, your input is invaluable.
Ken


kubes40    -- 04-16-2020 @ 9:20 AM
  Ken, I tend to use Ft. Wayne as well. They do good work and are actually very reasonable. Do you agree?

Mike "Kube" Kubarth


39 Ken    -- 04-16-2020 @ 9:35 AM
  Yes on both counts. Plus, they will rebuild "your" pressure plate and clutch disc back to original specs or to your specs depending on your application by using stronger springs or marcel.
Ken


TomO    -- 04-16-2020 @ 6:51 PM
  Carl, if you are referring to this item:
https://www.ebay.com/itm/NOS-Ford-flathead-1932-56-V8-special-clutch-pressure-plate-bolt-set-6-hot-rod/263663631948?hash=item3d6393be4c:g:sYgAAOSwHLFa7m2k

they are not shoulder bolts. They look like the description that I gave.

I agree with Kube and would send the pressure plate and disc to Fort Wayne Clutch for a rebuild. When you get it back, have the flywheel and clutch dynamically balanced. That should solve your vibration problem, if it is not related to another engine problem. I would not drive the car or run the engine with the vibration, it could ruin your main bearings.

After looking through my restoration log, I found that the last time I did a clutch job, I bought the correct bolts from Roy Nacewicz and did not use hardware store bolts.

Tom

This message was edited by TomO on 4-17-20 @ 6:30 AM


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