symptom help request
 

Hey all,

So I had a low mileage used tranny installed about two months ago when the original died. It's been driving and shifting fine until recently, when i've noticed on three different occasions, about a week apart, that it slipped shifting from 2nd to 3rd (revs briefly before shifting)(while in 3). I drive in 3 when the posted speed limit is below 40. Again, it doesn't happen regularly, just once, and on 3 separate occasions.

I've got a 6 month warranty on the tranny and I need to know if I should go back and get my money back. Four months to go!

Thanks!

Re: symptom help request
 

Sounds like the brake band is starting to wear and needs to be adjusted asap to prevent it from getting worse and wearing out the high gear clutch.

Slight chance that it could be the tps but I would bet on the brake band.

Re: symptom help request
 

Thanks Nate! There is a good transmission shop here so i'll see if they can do it.

Re: symptom help request
 

how difficult is it to access in order to adjust? just curious I spoke with the shop and he said he needed to take a look to see how easy it was.

also, should i avoid driving in 3 until it gets adjusted? Going to get it done tomorrow but just curious - is the brake band what provides engine braking?

Re: symptom help request
 

No Dave the over run clutch does that. Third gear will be fine, you can keep driving in third. You just need to do the brake band adjustment, to stop the flaring from second and third.

Harvey.

Re: symptom help request
 

That's right. I forgot. Thanks Harvey!

Out of curiousity - what exactly does the brake band do?

I have to say i'm amazed with the incredible technical knowledge you guys have. This site is a godsend.

Re: symptom help request
 

When it is in first gear, the forward clutch is on so the epicycle gear-set is giving the lowest reduction. For second the brake band comes on to hold the front Sun gear stationary so that the epicycle gears have to walk around the sun gear. This reduces the reduction to give second gear ratio.

For third gear the band is released, and the high clutch is applied at the same time. If the band is loose, it releases before the high clutch has come on, so the box goes back to first, till the high clutch clamps up.

Nothing is slipping when this happens, it is just a matter of timing, but it can start the band slipping when in 4th gear that will burn it out. That's why it is important to do the adjustment early.

Harvey.

Re: symptom help request
 

so it revs briefly because it's in first.

It does it VERY briefly and when i'm going like 25-30ish.

So hopefully that is inline with what you guys think and indicates early symptoms of a loose brake band. I'm taking it in tomorrow.

Re: symptom help request
 

Yes when the band comes off, it is in 1st till the high clutch comes on to get third.

It has a fair bit to do with a the line pressure that is the operating medium for the change over. The low speed and the light throttle will produce a low line pressure, so the action is not as sure as it would be. Then the line pressure is dropped again during the change, so that is when the flair is first felt.

Harvey.

Re: symptom help request
 

So the quick change would probably help as well wouldn't it? I think I'll be buying one next week.

Re: symptom help request
 

Yes it will, but you must do the adjustment, as the Quick Change won't affect the light throttle changes. As its action increases the engagement pressure progressively as more throttle pressure is used.


Harvey.

Re: symptom help request
 

I've noticed mine doing this under light throttle, from this thread I gather it is the brake band, and not the TPS as I suspected? It doesn't slip or anything at all under moderate to heavy throttle, only if I'm just creeping along like in a 25 zone or somethng. I guess I will have to see if Don (master tech) knows some trick to adjusting it with the tranny in the car.

Re: symptom help request
 

Yes it can be done in the car, you can almost see it, down past the brake booster and the starter.:D A lot easier on a RHD.

If yours is an original transmission it may have a low line pressure from wear. That increases the amount of ATF leaking out of the pressure system, along with the low speed and low throttle opening it is too low to apply enough pressure.
If the adjustment does not fix it, you could use one of OT resistors to raise the line pressure to throttle position. That will increase the pressure at low speed.

Harvey.

Re: symptom help request
 

Or for now you could disconnect the dropping resistor for slightly line pressure.
The power light will flash, but it could help untill you ADJUST THE BRAKE BAND!

PS, Thanks, Harvey!:)

Re: symptom help request
 

My tranny is a Subaru reman unit with roughly 30k on it. I don't know exactly, I need to call Patrick and see if he still has the receipt from the car it came out of...