Ever since I did my swap, my speedo has always been off by +15-20mph. Is there anyway to re-calibrate the speedometer to display the correct mph? Car is a 91 Firebird w/ an 87 GN motor swap, 700r4 still and a Dana 60 rear.
Thanks!
Ever since I did my swap, my speedo has always been off by +15-20mph. Is there anyway to re-calibrate the speedometer to display the correct mph? Car is a 91 Firebird w/ an 87 GN motor swap, 700r4 still and a Dana 60 rear.
Thanks!
'91 Firebird - LC2 3.8, 6776S Turbo, Alkycontrol, S60 Rear, ProBuilt 700
You must have changed gears or tire size. The only way to change the MPH readout (because it is cable driven) is to change these little plastic gears in the tailshaft of the 700R4 trans. Getting them, installing them, getting the correct ratio gears? Goodluck with that part, im sure the info is out there.
Denny Villemure
PSSSSSSST!
Vortec 4200 Turbo IROC-Z on 15psi
10.85 @ 126mph
There are a few speedo drive vs driven gear calculators that will get you within a tolerance. You need to know your rear axle ratio. Knowing the tire size (if different from stock) will help get even closer.
Seen this out there if it's any help.
First I saw this page...........
http://www.firebirdcentral.com/Articles.asp?ID=258
Then there was this link on that page about speedo gears
http://www.v8volvo.se/mekartips/arti...eedo-gear.html
I Drag Race Because It's Fun, Not Because I'm Good At It.
91 is about the year they went electronic.
If you have plastic gears you are in luck. I have every gear & housing in stock & can calibrate what you need with tire height & gear ratio
If its electronic I need to know if the vehicle has a Drac module under the dash (pictured below)
If it has a drac you either need a new one made or one with dip switches installed like the one pictured.... I had several made for this issue with older vehicles.
If it has no drac I think you can recalibrate on the back of the dash.... its been years since I seen one of those.
I guess I should wait to do this after I swap the rear tires again. This is good stuff though. I found this thread on TGO as well - https://www.thirdgen.org/forums/tech...r-way-off.html.
It's not electrical. Sounds like I need to do some measuring and find the right driven gear size. @Detroit Gearbox I'll hit you up as soon as I figure out my numbers and what I need.
Thanks, everyone!
'91 Firebird - LC2 3.8, 6776S Turbo, Alkycontrol, S60 Rear, ProBuilt 700
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