Mechanics

TRANSMISSION OR DIFFERENTIAL

1995 Toyota Corolla • 4 cylinder FWD Automatic • 255,000 miles

I have a 1995 Toyota corolla 4 cyl. 1.6 litre engine and I was wondering if its the transmission or differential that's acting up.
Sometimes when I turn a corner to go up a hill my transmission slips, it seems to lose power to the drive wheels and it over revs. I brought it to a tranny specialist and he said it was known that the differential in this make and model have differential problems namely a seal between the differential and the transmission. Also it seems to be slipping at 80 kms an hour on the highway. But these problems aren't consistent, He checked the condition of the trans. Fluid and it seems alright I was thinking maybe the trans filter or something. Or maybe the torque converter. I would really appreciate some help. Thanks John
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Johnnnyyy65
May 6, 2011.



The transmission and differential are all in the same housing. Before you get too excited, has anyone checked to see if the fluid level is low? That will let the internal pump suck up air instead of fluid when the fluid runs to one side when you go around corners.

I don't doubt your specialist's comment about a known seal problem, but what is the typical symptom that problem causes? Did he say that seal will cause the problem you're having? I'm happy you already visited a specialist. That is the best place to start.

Caradiodoc
May 6, 2011.
I was wondering if you could clarify is it the internal pump in the transmission or the differential your referring too. Thanks for the prompt reply I appreciate it. And would you have an exploded view of the transmission and differential assembly.

Tiny
Johnnnyyy65
May 6, 2011.
All automatic transmissions have a pump that is driven by the engine. It pressurizes the fluid to push on the many shift valves and it is directed to the various clutch packs. That pressurized fluid pushes on large flat pistons, (discs) that squeeze the clutch plates together to apply them. Since air can be compressed, when it is drawn up instead of fluid, not enough pressure can be built up to hold the clutch plates together with enough force so they slip when you try to accelerate.

The differential was the center section of the rear axle on rear-wheel-drive cars but since it's up front now, it just makes sense to build it into the transmission. That's why we called them "transaxles" for many years but that term has kind of fallen by the wayside. In every transaxle I've ever seen, the differential section uses the same automatic transmission fluid that circulates in the transmission section.

I don't know the story about the seal you mentioned so you'll have to rely on your specialist's experience. I'm sorry that I can't post a diagram of the transmission. I'm supposed to have access to one of the online repair manual services but it never accepts my password.

Caradiodoc
May 6, 2011.
Thanks for the reply I will check the transmission fluid tomorrow when its light out. It explains a lot.

Tiny
Johnnnyyy65
May 6, 2011.
Be sure to check the instructions that are usually printed on the dipstick. If nothing is specified, the typical procedure is to have the engine running and warmed up, run the shift lever through all the gears, then end up in park, wipe the dipstick off before checking the level. That's important because fluid will be getting splashed around and will splash up higher on the stick than the actual level. There will be a small range that is acceptable. Too much fluid is just as bad as not enough. That's because the higher fluid will get caught by the rotating parts and get air bubbles whipped into it. That air will compress and cause valves and clutch packs to not work properly.

I'll be out of town tomorrow but I'll see your reply in the evening. Holler back with some good news.

Caradiodoc
May 6, 2011.
I was wondering if the tranny filter could be the problem because I don't know if it has ever been changed. Provided of course that the transmission fluid level is fine and in good condition. Thanks John

Tiny
Johnnnyyy65
May 6, 2011.
Differentials would not cause the symptoms described. You have a slippage between the torque converter or trsnamission cklutches and more often than not, it is the clutches. Toyota torque converters seldom gives problems.

Transmission is equipped with a maintenance free strainer instead of filter and if it is clogged badly, replacing it is not going to help because the trans is about to retire itself.

If your trans is equipped with the trottle pressure cable, check its adjustment. If it is too loose, fluid pressure would be low and that can result in intermittent slippage.

KHLow2008
May 6, 2011.