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Discussion Topic:
Tightening Motor Mounts
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len47merc |
02-24-2017 @ 5:08 PM
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Senior
Posts: 1165
Joined: Oct 2013
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Any magic or science to tightening the front motor mounts on '46-'48 59ABs? The originals on the car were shot and unable to be 'copied' in terms of 'bulge', and the first set I put on the car when bringing it back to life was recently found to have been labeled correctly but were the incorrect part for this application. Some of you may recall the thread on that and my error in not comparing the new set to the originals. Now I have a new correct set in hand and plan on installing it tomorrow. Basically is it all just personal feel or do any of you have a tried-and-true method to consistently hit the 'optimum' tightness mark every time?
Steve
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cliftford |
02-24-2017 @ 5:55 PM
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Posts: 845
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Steve, I don't ever recall seeing any torque specs for this. I've always tightened them until I see some bulge. Then I start the engine. rev it a few times and watch for excessive engine movement. Maybe someone has more information than I have. but I don't think it is all that critical in terms of ft/lbs of torque.
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len47merc |
02-24-2017 @ 6:16 PM
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Thanks cliftford - yeah, that's been how I've attempted to do this myself. Searched for a while today to see if there was any definitive, objective process information and couldn't find any. Thought I'd ask a stupid question and maybe learn something beyond what made sense to me the first go on an EFV8. Seems there should be something - too loose and (minor) clutch chatter results, too tight and excessive engine vibration through the car, etc.. In the absence of anything definitive I'll follow my gut again and follow the procedure similar to what you stated, this with the intent to get them just tight enough to eliminate any clutch chatter yet soft/loose enough to let the mounts absorb the inherent vibration from the motor. Just hate to possibly go through multiple iterations to get it 'just right' if a procedure exists to short cut the time and effort. Thanks again -
Steve
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len47merc |
02-25-2017 @ 6:31 AM
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Decided, given the castle nut/cotter pin design of these new mounts (Drake/Carpenter), to simply tighten until the cotter pin hole was exposed just enough/first castle to allow pin insertion and call it a day. Both bottom and top bushings are tight/cannot be rotated and the bottoms have just the very slightest amount of perceptible compression/bulge. Will report back later today on effectiveness (engine movement, clutch chatter vs. engine vibration). Fwiw
Steve
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supereal |
02-25-2017 @ 1:31 PM
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Joined: Oct 2009
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Be sure that you have all the parts, including the cupped and flat washers. Some kits have been shipped with just the rubber pieces. A good kit with also have the special stepped bolt. Tightening is no big deal, except someone will have to hold the bottom of the bolt while you tighten the castle nut until there is a noticeable bulge in the big donut.
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Drbrown |
02-25-2017 @ 8:07 PM
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len47merc .... went through that experience with my '47 59AB about year and half ago. No one ever seemed to be aware of any torque spec. The kit I bought from Steele Rubber Products provided everything except the wide flat washers that go on top, underneath the water pump arms - no problem, cleaned and reused existing. The parts matched appearance wise but when done the water pump arms sat about a 1/4 to 3/8 inch higher than before. I had to use a lot of muscle to tighten those castle bolts down enough to get the cotter pins installed. The new rubber didn't "squish" much at all and there seemed to be a small amount of vibration right after installation. However, after I drove the car a number times everything settled in and all is good now. I did check the carb linkage, exhaust pipe clearances and the clutch never acted up.
This message was edited by Drbrown on 2-25-17 @ 8:08 PM
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len47merc |
02-26-2017 @ 5:18 AM
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supereal - appreciate the reply and I have confirmed I have all the parts. Drbrown - your description is almost exactly as I have found these new mounts' behavior to be. While the amount of torque required to get the castle nut to clear the cotter pin hole did seem perhaps a bit high to me, I will correct my earlier statement and say that at this 'minimum' tightness required to get the cotter pin in that the bottom bushing is now quite more bulged than I'd expected is 'should' be. Again, that's only my limited experience expectation. The new top bushing did not bulge nearly as much as I expected - almost imperceptibly, but the bottom much, much more - perhaps this is normal(?). And yes - the clutch is as smooth as it ever was now, maybe even better. To your point there is a noticeable amount of vibration on the first two very short test drives at a couple of specific rpms/harmonics that I've never felt before that has an item or two vibrating/rattling that also never have before. Not oppressively bad but you can feel it in the steering wheel at those rpms. Initially I was considering removing the cotter pins and castle nuts and installing the original Marsden nuts so I would not have to tighten them quite as much but thought perhaps the mounts just need to 'settle in' and I'd drive it for a hundred miles or so to see if it did improve before taking this step. Based on your experience and comments I feel a bit better about this being the case. Follow-up later with results and perhaps a pic of the bottom bushing 'bulge'. Thanks again guys - Steve
This message was edited by len47merc on 2-26-17 @ 5:42 AM
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len47merc |
02-26-2017 @ 7:52 AM
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Went out for a 45 mile Sunday morning cruise and notice a more than perceptible improvement today in the engine vibration so will let this go for a while to see if it completely 'settles in' as Drbrown put it. Attached is a pic of the passenger side bottom mount bushing. The top bushing is so stiff that I can see little to no compression of it, only the bottom bushing seems to be compressed and to my inexperienced eye (on this issue anyway) it seems excessively so, but perhaps this is normal for the repop mounts - ? The original top and bottom bushings, which had 37K miles on them, were equally compressed, relatively speaking. Given the clutch is so smooth and the engine vibration appears to be improving perhaps this is correct. Note again the bottom and top bushings have been confirmed to be seated correctly, all parts are installed in the correct orientation, and the castle nut was only tightened to the absolute minimum tightness to insert the cotter pin at the corresponding first 'castle'. Thanks kubes40 to your reply on the other thread. If long-term, acceptable engine vibration improvement is not realized on this set I'll give Drake's a go. Carpenter is so close and given these are replacements to correct the erroneously provided first set it was necessary to go with theirs for this iteration. Their top bushing seems extraordinarily stiff compared to the bottom. Comments on the bottom bushing 'bulge' appreciated. Steve
This message was edited by len47merc on 2-26-17 @ 7:56 AM
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len47merc |
02-26-2017 @ 7:59 AM
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Man I do this a lot - attached is the pic.
Steve
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kubes40 |
02-26-2017 @ 8:17 AM
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The bolts that come with the repop mounts are shorter than the authentic. That may be why it seems you have to compress the rubber so much. Drake, in my opinion, makes the best quality mounts. However, his bolts are also too short. My .02¢? Use his rubber mounts and the authentic bolts.
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