Speedometer gear drive q
Thread Starter
Drifting
Joined: Aug 2007
Posts: 1,924
Likes: 6
Speedometer gear drive q
Will the gear drive out of my removed 81 automatic fit and work in the 79 Borg Warner 4 speed I replaced the auto with?
My {1981} 85 mph speedometer is waaaaaaaaaaaay off.
(yes, I'll get rid of the 85 mph unit someday, but I have other more important things to tend to on the car)
My {1981} 85 mph speedometer is waaaaaaaaaaaay off.
(yes, I'll get rid of the 85 mph unit someday, but I have other more important things to tend to on the car)
Safety Car
Joined: Oct 2000
Posts: 3,547
Likes: 12
From: Carbondale Pa.
Only if they are of the same general design, some automatics use a very much larger (diameter wise) gear. The T-10 should take a smaller size wise gear that gets placed in a bullet shaped housing. Is any of this clear to ya, if not someone with a better grasp of explaing it can help out,,,Peace,,,Moosie 
P.S. if the speedo is reading too fast you need a gear with more teeth to slow it down, how many ?????who knows. Try looking @ a few vendor websites for a picture of what I mean by difference in physical size, DR.REBUILD comes to mind.
P.S. if the speedo is reading too fast you need a gear with more teeth to slow it down, how many ?????who knows. Try looking @ a few vendor websites for a picture of what I mean by difference in physical size, DR.REBUILD comes to mind.
Last edited by moosie982; Oct 8, 2007 at 10:18 AM.
Race Director
Joined: Sep 2001
Posts: 10,560
Likes: 439
From: Wellington, FL
St. Jude Donor '11 thru '25
You need to count the number of cogs on the gears. If the count is different, mph will be off. This is assuming the physical sizes are the same 
Last edited by Jud Chapin; Oct 8, 2007 at 10:10 AM.
Thread Starter
Drifting
Joined: Aug 2007
Posts: 1,924
Likes: 6
It's a '79 M21 trans and an '81 2.87 rear end
