Transmission Shimming

How to correctly shim a 4 speed transmission

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1950HD1950
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Transmission Shimming

#1

Post by 1950HD1950 »

Hello gents,

looking for advice on shimming a 4 speed transmission. I have torqued down the transmission plate which needed a shim on the rear left corner, then i tightened down the 2 rear nuts of the transmission and have a small gap at the front between the trans and the mounting plate. Is it just a matter of shimming to the plate? Is this the correct way to go about it?
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Re: Transmission Shimming

#2

Post by PanPal »

I’ve never seen a shim there. Better for the shim to be between the plate and the frame. Perhaps the frame took a hit. The plates don’t normally need shims either.
1950HD1950
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Re: Transmission Shimming

#3

Post by 1950HD1950 »

Frame has never been in an accident, it's as straight as an arrow.
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Re: Transmission Shimming

#4

Post by awander »

1950HD1950 wrote: Sun May 15, 2022 12:57 am ...it's as straight as an arrow.
Well, except for the transmission mount... :?
1950HD1950
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Re: Transmission Shimming

#5

Post by 1950HD1950 »

I believe the issue is the transmission mounting plate, will get my mate you check it on his milling machine.
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Re: Transmission Shimming

#6

Post by Robbo »

When I did my engine and trans I used this advice from the knowledge base.

Motor Mount, how-to
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Re: Transmission Shimming

#7

Post by Frankenstein »

Good advice in the knowledge base post. Two important parts in that are, one: motor and trans are both level to each other. The goal are that motor mainshaft and tranny mainshaft are true or level with each other. (this for good clutch operation)
Second point made in knowledge base: No stress on tranny/tranny plate when pulled up tight. Shim the mating of the two so that one stud isn't taking undue stress. It's a good idea to check that the mounting plate is flat and true as well. Had one recently that got rust between the two sections and caused warpage. Ground off the welds and flattened the junction between the two parts, then rewelded together.
Again,you're after no undue stress on the tranny case, and making sure that the tranny mainshaft and engine shaft are absolutely true and parallel to each other for smooth, grabfree clutch operation!
DD
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Re: Transmission Shimming

#8

Post by RooDog »

When Phil Ross came up with the idea of a front belt drive the MoCo told him it wouldn't work. The main reason being that the parallel orientation of the crank and tranny MS was of significant importance fort the belt to track true. In most belt drive installation instructions that procedure and corrections are spelled out in great detail. A chain drive, on the other hand is tolerant to some misalignment, but regardless of alignment the component parts must mount flat and true. So shimming, and or machining may be in order to correct the mounting footprints. Do also bear in mind that the tubular frames are flexible, and factory assembly tolerances vary widely from absolute precision. Again why they said the belt drive would not work, even after Phil road from his home in California to E-Town, Ky on his belt driven Shovelhead....

https://supermax.net/Pages/ManBehindBeltDrive.php

Too bad that when Phil passed on to Harley Heaven, his survivors lacked what ever it takes to keep SuperMax afloat, and now his good stuff has passed on into history also....
Same for Alan Sputhe, but that is another story....
....RooDog...
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Re: Transmission Shimming

#9

Post by 1950HD1950 »

Thanks for the replies. I also found some interesting info in this article https://forum.antiquemotorcycle.org/bbo ... t-question
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