Arrrggghhhh! where did fourth gear go???? slipping?

[Dan RareGP]

ok, im kinda green with tranny problems as Ive never had any before but the car shifts fine in all gears and the tourqe converter locks up in third.
however when im on the highway im in OD at like 3000rpm and If I give the car any gas the revs shoot up to over 4000rpm before I start making anymore power again and then its still not transfering the power correctly. I think this is "slipping" but not sure. If im in D3 I dont get the problem as 4th is locked out. Dunno whats going on here. Had the tranny flushed and filled today and the shifts on 1,2,3 cleaned up nicely but 4th still has this issue. Fluid looked good and no metal on the magnet as I asked to see it. Can I just drive around in D as opposed to OD to prolong life as I hate to see my valvetrain taching out at over 4k on the highway for long periods of time. Is my tranny gonna die? or am I just never gonna get full use of 4th gear? I added the Lucas magic oil stuff today too. whats going on? burnt clutch pack or whatever? what does it take to fix it short of a full rebuild?


Car is a 1990 Turbo grand prix with 130,000 miles and 40,000+ miles on a rebuilt tranny.


minor correction, it still occasionally shifts late going into third gear, but rare and not very severe. all other shifts are good if not great.

Thanks
Dan

[Chris A]

probably. 4th gear is very very weak and prone to failure. Typically it will kinda weld toghether, but there are other parts that can break or cut it apart so it won't work well. Driving in D can work, but you are right, cruising at such high rpm's isn't good.

chris

[Dan RareGP]

got a quote today from a reputable rebuilder for about $1300. ops:


they only do full rebuilds using OEM parts. Anything I need to communicate to them before the rebuild occurs such as any packets of info by Jeff M floating around?

what if I dont decide to rebuilt it until say I get out of school for the semester in may? It drives now and shifts high and obviously sucks on the highway but I can live with it until then. How long will the tranny last like this? will it completly die out and shit on me at the wrong time? I want to either get this done next week or wait until summer. also are partial rebuilds possible and or worth it? the shop will only do full rebuilds.

[TurboGTU]

Funny thing....My other brothers Mercury Cougars AOD is doing the same thing. All gears are fine but OD goes away when any little acceleration is appled. We came to a conclusion that the OD sevo is messed up and/or the OD Clutch band is worn out.

Don't know if this applies to the 440s. We will check the Cats AOD.