Houstonhood32

I have a 94 Toyota SR5. It's an automatic ( I know, I know, but I got an awesome deal on it). It drives great, but won't move in reverse in 2 high or 4 high. In 4 low it's strong in reverse. I'm thinking it's my transfer case. Anyone have any ideas? Thanks.

RJR

Give us a little more detail on the symptoms. When you say it won't move, does the engine rev like it's in neutral, or is the engine lugging like you've got your foot on the brake? Any noises (like grinding or slipping) from the drive train anywhere?

It's pretty hard to imagine how the transfer case could transmit torque in one direction and not in the other. It's just planetary gears, a chain, and some sliding shift collars. No directional elements at all.

I would suspect a slipping reverse clutch in the auto-tranny. The lower gearing of 4LO requires ~2.5X less torque from the tranny to move the vehicle, and so could mask a weak clutch.

Ron

Houstonhood32

Thanks for you response.

If you rev it up to 4,000-5,000 rpm it will creep backwards like you have your foot on the brake, just barely enough to move the truck. Having a friend listen from outside the truck and me on the inside, no grinding or slipping can be heard.

So you're saying that if the truck drives, then shifting collar is engaging and you should get power to the rear wheels on matter if you are in drive or reverse?

Also if it is the transmission, could it be a weak pump? From what i understand, reverse takes the most hydraulics to work correctly?

Is it worth overhauling or would a used tranny be an easier option without knowing exactly what the problem is?

Thanks in advance

RJR

Thinking about it more, I'm only really familiar with the manual transmission version. With an automatic, does the transfer case still have a lever on the floor, or is it shifted electronically? If the latter, there could be a valve or clutch problem in the transfer case.

I would think a good automatic transmission shop should be able to give you some advice without having to spend a lot of money. They've probably seen similar things before.

Houstonhood32

Yea there is still a lever in the floor. Thinking through it, if it is getting power to the rear wheels at all should mean it is not the transfer case.

I'm just gonna have to take a look at the transmission.

rustypigeon

It's not the transfer. The transfer only provides gear reduction and 4wd engagement.

You have a slipping clutch pack in the transmission. It is slipping because it is either worn out, or it is not getting enough line pressure to operate properly.

Do all the forward gears operate with no slipping? 3rd and o/d in particular?

Houstonhood32

Yes all other forward gears work fine. No slipping. I drove it almost an hour home when i bought it without any problems, and checked the other gears.