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kw90supercoupe
07-15-2014, 01:44 AM
I just swapped my auto to a 5sp and the rpms are up their on the highway. So i have the rear end gears from the 5sp car. Do i have to change the pinion gear to. If so can i drop the rear end without pulling one of the rear hubs out. Also dosent the autos have a posi and the 5sp has a open diff. Which one would be better to have both wheels spinnin.

S4gunn
07-15-2014, 02:07 AM
I just swapped my auto to a 5sp and the rpms are up their on the highway. So i have the rear end gears from the 5sp car. Do i have to change the pinion gear to. If so can i drop the rear end without pulling one of the rear hubs out. Also dosent the autos have a posi and the 5sp has a open diff. Which one would be better to have both wheels spinnin.

1) You must change the rear end gears as a matched set (pinion and ring gear).
2) You don't need to disconnect the hubs from the axles but you will need to pull the axles out with the rear hubs attached in order to drop the diff.
3) You don't have a posi, you have a "tractionlok" unit. While TLs were options on automatic cars, it's surprising that a SC-equipped 5spd would NOT have a TL unit.
If your 5spd diff was indeed an open diff, you will only get one-wheel peel.

Recommendation:
* It it was a stock unit, the automatic has a 3.08 or a 3.23 gearing inside the diff depending on the tbird model. The difference between that an the 5spd diff (2.73) isn't that significant. I would personally prefer the increased acceleration of the shorter gearing over the slightly higher RPMs at hwy speeds.
* If you do decide to swap back in the diff that came with the 5spd (or just the gears), take the time and effort to rebuild the TL unit inside (i.e.: replace the internal clutch discs) while you are swapping out gears.
-g

Jacob_Royer
07-15-2014, 03:28 AM
Nobody likes 2.73s so there is probably someone that will sell you a whole rear end for dirt cheap takes about 2hrs to swap tops.

820
07-15-2014, 07:07 AM
Nobody likes 2.73s so there is probably someone that will sell you a whole rear end for dirt cheap takes about 2hrs to swap tops.

I wouldnt say that nobody likes 2.73s.

KMT
07-15-2014, 07:11 AM
Some would claim that the 'easiest' way is to swap out the entire differential with one that is in good condition and has the gear ratio you want. Don't forget to check the fluid and consider the swap as a chance to refresh mounts. With any luck you can sell your old unit and reduce your costs.

BirdofPrey97
07-15-2014, 09:14 AM
I dont know of a SC auto or 5spd pre 94 (non traction control) that didn't come with TL. I like the 2.73 as the SC is driven interstate for 40 miles a day. That is the stock gear this 5spd came with. Had 3.27, but didnt like them with the 89-93 trans or the 94-95 trans.

From the way the question is presented as a suggestion take the rear in to a shop and have it swapped out for your safety and everyone else on the road.

Tim Groth
07-15-2014, 02:37 PM
I have a complete 5spd rear diff from a parts car if it's something you'd rather just buy and take your old one out - swap the new in ...I am sure many others on the forums that have parts cars do also.

I'd sell it for $50 plus shipping if you're interested.

Tim