Tranny question

[BoostLess7mge]

i have an 89 n/a and just swapped in another auto tranny from a 91 turbo(swapped the trans ECU as well). speedometer now reads higher than actual vehicle speed, is it as simple as switching a cable to correct this? and would it beneficial to me to switch the factory 4.30 rearend to the 3.73 that i pulled from the turbo car? thanks guys!

steve

 

[CRE]

You need to swap the sender gear from the old tranny into the new one. There are different gears for each diff. It's where the speedo cable meets up with the tranny.

You might need to drain the tranny first... you do with the W58 since the gear is on the bottom.


As for the diff.... you'll loose acceleration, but you'll gain top end speed and highway cruising will be at a lower RPM. It increased my mileage as most of my driving is highway. 3.91 is what I'd recommend for a diff swap on an N/A though, I don't imagine I'd like a 3.73 without some more power behind it.

 

[BoostLess7mge]

finally a simple fix. thanks for the quick reply!

 

[CassMori]

You need to swap the sender gear from the old tranny into the new one. There are different gears for each diff. It's where the speedo cable meets up with the tranny.

You might need to drain the tranny first... you do with the W58 since the gear is on the bottom.

finally a simple fix. thanks for the quick reply!

I didn't need to drain my w58 when I swapped out the speedo drive gear....but the one for the 4.1/3.9 gearset did not mate up with the gear in the transmission. The autos may be different from the manuals, though.:dunno:

 

[CRE]

Yeah, the auto is the same on both cars, same size housing and same diameter gear.

As for not having needed to drain your gear oil, I'm stunned... I got drenched. Also, the drive gear for the R154 has a smaller diameter than the drive gear for the W58... just enough to prevent it from mating up.