Aaron Cockerham wrote:I havent had any problems and I got everything from a 89Grand Am and the tanny was the same as the one in mine they are both automatics so if the grand am tranny held up to mine should and has[/quote
Yes botht he N/A sunbirds and turbo sunbirds, when automatic use the TH125C 3 speed w/ locking covnerter auto trans. Even 3rd gens used this trans for a while.
The difference is that the turbo auto trans has a higher rpm stall rating on the converter, different gear ratios AND a different final drive ratio. You'll be blowing thru tires like crazy in low gears because of how short the n/a gearing is.
I have yet to confirm it but I bet the turbo auto trans also has upgraded clutches and bands too and perhaps a higher interal pressure (IE a shift kit) because they felt different quite different from N/A trans and the trans definetly needs to hold more power.
That being said the auto trans doesn't even hold up that well to the STOCK power of a sunbird turbo, with the sunbird turbo auto trans, when racing. The TH125C especially stock, is not a strong trans.
The HM282 5 speed found in 2.0 sunbird turbos is nearly indestrictable as far as a FWD 5 speed trans go. You will blow a stock motor long before you blow the stock trans. Guys like Curtis walker have pushed 300 + lbs/tq thru them no problem on slicks over and over.
The isuzu MK7 trans found in the n/a applications is NOT strong at all, and is why GM switched to the HM282 for the turbo models. It also has poor / short gearing stock as well. The HM282's gearing is long and has a different final drive.