1980 corolla shifting problem

[bandag]

Hi all, I have a 80 corolla, all original, low miles 1.8 automatic, I just recently went from the original 165-13 tires to 15 inch custom wheels, the car shifted fine before the swap, now it seems like it won't shift into high gear but stays in second. Someone said I need to adjust the kickdown cable to compensate for the bigger diameter tires. I can see how to do this in the Haynes repair manual but I don't think I want to set it to original specs do I? Do I need to lengthen the cable? (by adjustment). Could there be something else wrong that's not letting the car shift? Thanks in advance for your replies.

[Zembonez]

How much taller are the new tires?

[Donald]

I think it is just coincidence that it stop shifting after you changed the tires, unless you got real crazy with the tire size, but even then, that should not matter.
Check your fluid level, then check the kick-down cable adjustment (to factory steeing). If those are good, have the tranny pressure checked. It might be going south.

[bandag]

Sorry, just getting back to this posting now. The original 13 inch tires are 23.3 tall, the tires on car now are 225/50/15 and are 23.8 tall. I tried not to go much taller but did go quite a bit wider, the car still sits at stock height, springs are not cut, did have to roll the fender lip so these tires didn't rub. they are on 8 inch wide wheels. Holeshot wheels, custom made.

[Zembonez]

Not enough difference in tire size to have much of any effect.

HMMMMM.

[Donald]

Originally Posted by Zembonez

Not enough difference in tire size to have much of any effect.

HMMMMM.

I say it is just a coincidence.
The tires shouldn't make a difference anyway. I think the tranny is loosing pressure internally.
Blown seal.

[bandag]

Don,
You mention trans pressure and that it might be losing it. After driving the car I have noticed a few times that the tranny dipstick is sticking up out of the tube about an inch. And I know that I didn't leave it that way the last time I checked the fluid. And I see that it has a rubber seal up inside the dipstick, if this is sticking up when I am driving could that be where the trans is losing pressure from and thus not shifting right?

[Donald]

Originally Posted by bandag

Don,
You mention trans pressure and that it might be losing it. After driving the car I have noticed a few times that the tranny dipstick is sticking up out of the tube about an inch. And I know that I didn't leave it that way the last time I checked the fluid. And I see that it has a rubber seal up inside the dipstick, if this is sticking up when I am driving could that be where the trans is losing pressure from and thus not shifting right?

Ummm, not quite.

This is a very crude description.

The way an automatic transmission works is that it has a series of pistons that are like doughnuts. Those are operater in sequence by the valve body, with pressure from the hydraulic pump. Each one, as it is pressurized, presses against a set of clutch plates, which hold or release planetary gears.
As one reaches it's upper pressure limit, the valve body (with springs and sliding valves), decides it is time to pressurise the next one, engaging the next gear.
If one piston has a leaking O-ring, the valve body has a leaking gasket, or the pump is worn, enough pressure might not be developed to operate the next piston, and engage the next gear.
I think, the most likely culprit is a broken piston O-ring, but there are other things inside there that can leak (accumulators, pistons with springs behind them that absorb the shock of shifting), causing a pressure loss. Those have O-rings too.

A propper pressure test should narrow it down to which is the probable culprit.

Now, the dipstick. The dipstick is not meant to hold pressure, but its blowing out, is an indication of an internal problem.