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Bottom End, Thrust Washer Selection

Moderators: Curt!, Pa

Post Wed Mar 16, 2011 6:01 am

Posts: 85
When scratch building a bottom end from scout cases and Chief Z wheels and new or nos pieces, the pinion & drive shaft thrust washer choice starts at .047 & gets thicker from there. Without the luxury of disassembling the complete motor, noting end play & checking current thrust washer, where do you start determining which size thrust washer?

Logic suggests start thin & get bigger. Is there more to it than that? I understand this question will be
answered when wheels are in the cases during a trial assembly, but until then...

Post Wed Mar 16, 2011 7:00 am

Posts: 634
Location: Wisconsin, USA
I use a telescoping gage and a micrometer to measure the distance between the races with the casers bolted together, then take a measurement of the thrust washer surfaces on the flywheels with an old non calibrated type caliper. I use a dial caliper to measure between the points of the old style caliper. Subtract the flywheel measurement from the race measurement, divide by 2, add clearance and you should be in the ballpark. I assume you are trying to order a minimal number of the thrust washers for the job. The problem is, if you are going to center the flywheels in the cases, you may need to use completely differant size thrust washers.

Post Wed Mar 16, 2011 1:56 pm

Posts: 85
Thanks for your reply. I considered something along the lines of your suggested method. I hadn't considered the issue of different shimming combinations for actual centering as you pointed out. My thought was to simplify the ordering process, but maybe that isn't possible.

Post Sun Apr 10, 2011 11:05 am

Posts: 202
Location: Middle England UK
I don't know what range of sizes the washers come in,or what the tolerance is for end float,but maybe you can get away with ordering four washers.
Work out using above method what you'd use as a matched pair of washers.
Now work out if you'd be within tolerance if you used one size up on one side,and one size down on the other.
If it looks good,order those four.You then have the option of moving the rods over by the minimum amount.

Post Fri Apr 15, 2011 12:49 pm

Posts: 85
YES! that will be my approach...just couldn't get there without someone breaking into baby steps.


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