I swapped trannys from my cars. Both the same gears and same specs, gear ratio wise. But one car is over, and the speedo is about 25mph higher than what it should be. Any ideas?
Speedo is off by about 25MPH
- Thread starter 7upstang91
- Start date
bgdowski
Member
Did you use the Vehicle Speed Sensor (VSS) from the old tranny or just keep the VSS from the new(er) trans in there? The new(er) trans may have a different VSS gear calibrated for the rear-end gear ratio that was in the vehicle it came out of, not your rear-end ratio...
The tooth count is denoted by different colors... Ex: Red gear = 19 tooth for 3.73 rear gears (certain year t5s).
The tooth count is denoted by different colors... Ex: Red gear = 19 tooth for 3.73 rear gears (certain year t5s).
MustangLX-5.0
Founding Member
Do you mean you swapped trannys from your 7-up to your 87 notch? Are they AOD's or T5's? Or is one a T5 and the other an AOD? If the latter is the case, then you can't use an AOD speedo gear in a T5 as it will be off. Unless you meant the trannys are the same, spec wise.
OT, sorry to hijack the thread but could you send me that pic of the swaybar when you get a chance?
OT, sorry to hijack the thread but could you send me that pic of the swaybar when you get a chance?
cjrpony
Member
Check to make sure the same color gear on the output shaft of the tranny is the same. I believe they came in 6 tooth (black), 7 tooth (yellow), and 8 tooth (green). I have had this problem before and it turned out I had the 8 tooth and I needed the yellow. Different years had different colors on otherwise same transmission. I had a link to a chart that showed the different combos, but it is dead now.
This maybe my problem. Dang, not sure I want to take it out again. But I know it came out of a 1990.
Ones a T-5 the other a Tremec t5. The tremec is just stronger. Both are in 90 motors. Same rearend gears and everything.
cjrpony
Member
I found a chart in a catalog that has the different combos in it. A 1990 T5 should have an 8 tooth (green) gear on the output shaft. Pull your speedo sender out of the tranny and you should be able to see it. I'll bet you have a yellow one in there. Or you have the green gear but your speedo has the gear for a yellow one. My cars' speedo was way off when I bought it and that is what it was. You can either swap it out or just get the correct gear for the speedo. Tell me what rearend ratio and what color output gear you have and I'll let you know what gear you need.
I once bought a t 5 trans from a junk yard from a 90 mustang to go in my 84 gt 350 and the speedometer was way off cant remember what way high or low but pulled it back out and found the junk yard tried to stick me by selling me a 4 cylinder trans instead of a 5.0 trans.
I just had the tranny out to do the clutch, darn. Where is the speedo senser? The speedo cable that goes into the tranny?
