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Speedo Calibration

blkcorvair

Jedi Knight
Offline
Anyone know a good source for getting a speedo re-calibrated. I put a 4.22 diff in my 76 (Normally 3.9) so Id like to re-calibrate the speedo. I was also wondering if I bought an early speddo from a 4.22 car if this would coreect my prob. (dont know if the 1500/1275 trans have the same speedo ratio???????)
 
One of the guys here has a site on adjusting the spedo for speed calibration, but the odo is a fixed ratio and probably needs a part for the correct diff ratio. I know the MGB has different drive gears in the transmission.

According to the pdf
https://pcbunn.cacr.caltech.edu/jjb/TR6/speedo.pdf
there are several different odo drive gears, interchangable from most Smiths spedometers.
 
Any good speedometer shop should be able to sell you a geared adaptor to re-calibrate your speedo. This is something that the old hot rodders did all the time.
 
Either sell some of them or build a larger garage.
 
When I did this in the past, I just used a GPS and marked the speedo at a few points with the corrected speed
(I used little pieces of white tape marked "35", "50" and "65").

Cheesey, but simple and easy.

If you don't have a battery-powered GPS, I'll bet you can borrow one from friends or family...lots of folks have them these days.
 
jlaird said:
Either sell some of them or build a larger garage.


LOL I just rented a 1 bay garage to build my Westie in. And the Benz V-8 is up for sale....
 
Surprisingly, no one has mentioned Paul Asgeirsson of Morriservice in Portland. Paul has various adaptors to accomodate various gearbox/rearend/tire/wheel combinations. Give him a call and see if he can fix you up. I told him "Datsun gearbox/3.9 pumpkin/70 series tires" and he sent me one that has proven to be pretty accurate. Small device like the original tachdrive for the generator, mounts between the trans output and the cable.

Glen Byrns
 
Glen thats what im looking for. Id like to get 2 adaptors so i can swap out the pumpkins and keep the speedo mostly accurate. ill give him a call!
 
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