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TD TF gearbox sliding hub clearance

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Tim66 Avatar
Tim66 Silver Member Tim Burchfield
Toledo, OH, USA   USA
1951 MG TD
1953 MG TD
I bought two new sliding hubs for my TD gearbox rebuild. I have seen various clearances posted to determine if the synchronizers are worn. I thought I'd post pictures of the synchronizer clearance (average) when new sliding hubs are installed. This will give a starting point when determining synchronizer clearance. Other more knowledgeable members can advise what the minimum clearance should be on a useable synchronizer. This is just a starting point. BTW, the MOSS 1st 2nd gear sliding hub took a lot of filing of the grooves and lands to get a smooth sliding fit on the mainshaft. I don't know if others have had this issue.

Tim



1951 MG TD TD26711
1953 MG TD TD12524
1980 Corvette

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sliding hub clearance.jpg    55.8 KB
sliding hub clearance.jpg

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rowinghuge Avatar
rowinghuge Silver Member Hugh Pite
Sidney, BC, Canada   CAN
Tim, these clearances seem very high. I measured some factory NOS hubs and found a clearance of about .090". Are you sure that there is no dragging on the syncros when the gearbox is assembled?
0.045" clearance is the minimum clearance. At about this clearance the the gear in question is touching the steel part of the sliding hub and not the brass synchro' ring.
Hugh Pite

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Tim66 Avatar
Tim66 Silver Member Tim Burchfield
Toledo, OH, USA   USA
1951 MG TD
1953 MG TD
Hugh, that's what I measured. I pushed the synchronizers together firmly.

Tim



1951 MG TD TD26711
1953 MG TD TD12524
1980 Corvette



Edited 1 time(s). Last edit at 2019-03-02 01:05 PM by Tim66.

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UMG0251 Avatar
UMG0251 Platinum Member John H Twist
Grand Rapids, MI, USA   USA
1962 MG MGA MkII De-Luxe "The A"
You want to lap the synchos to the speed gear faces. I do this on a lathe. Use valve lapping compound. My experience is that many of the synchros don't work out of the box -- this lapping ensure that the faces are parallel and the synchro grabs tightly. You might find the clearance between the speed gear and the sliding hub less after lapping.

John Twist
University Motors


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Tim66 Avatar
Tim66 Silver Member Tim Burchfield
Toledo, OH, USA   USA
1951 MG TD
1953 MG TD
Thanks John. I assume you mean putting the lapping compound between the brass synchro ring and the mating surface on the gear. I also assume the lapping compound will not damage the surface of the mating ring on the gear. If that correct? I don't have lathe but I think I can use a drill press to do the same thing.

Regards

Tim



1951 MG TD TD26711
1953 MG TD TD12524
1980 Corvette

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