I have a rebuilt 42re in my 2000 WJ and it's okay, but it shifts way too softly. They say that's the way it's supposed to shift. Well, maybe for an 80 year old businessman, but I'm a 75 year old ex-drag racer and it's just not as smooth as the original one was, even after it had 200K miles on it. It seems the 1-2 shift is the worst. At light throttle starting from a stop, it seems to let go of 1st for a split second before it grabs 2nd. The 2-3 shift is only slightly better. I can definitely feel the 3-4 shift and the lock-up changes and the throttle cable is set perfectly for load downshifts when required. It's better at heavier throttle, but still not to my liking. I talked to my mechanic about it and he said he has to check with the rebuilder because he doesn't want to void the warranty by messing with it, but he's busy and hasn't had the time or thought about it. I'd be interested in your thoughts on the subject. Thanks for your time.
Not an expert by any means, but certain principles apply. One is the accumulator cylinders. Usually two. One for the band and the other in the valve body fills with oil and is used in shifting. The spring rate in that cylinder affects shift speed and that positive feel you are looking for. Changing that spring is not tough, though you do have to drop the pan.
Here, this will explain what I am trying to say with proper terminology. Having trouble with the next page, but it is the view with the pan off of these parts
Yes, I am aware of accumulators and how they work. My brother built a THM 350 for his Chevelle and he reversed the accumulator springs and pistons so when it shifted, it knocked mud out of the fenders when it shifted! When I rebuilt my 700R4 in my Chevy truck, they suggested flipping the piston and spring in the 4th gear accumulator so the shift would be solid when pulling a load. That worked very well. I was thinking the accumulator spring rate could be tweeked for this one, but I didn't want to do anything until I was sure. The purpose of accumulators is to reduce the sudden inrush of fluid pressure to soften the shift, but I think they overdid it in my trans. Thank you for the confirmation. Now to do some research on what springs to use or maybe just cut one coil off each of them.
Now see, I was thinking a weaker spring so the fluid pressure build quicker when actuating the clutches. The idea of flipping the pistons and springs is so the chamber is full of fluid already and doesn't have to fill, thus reducing the time until max pressure is applied.
After watching a couple of Chrysler transmission classes, I see the 42re only has 1 accumulator in the main case for shifts up to 3rd and a second one in the valve body for 4th. There are servo pistons for band engagement and the accumulator is a balanced double spring type and is controlled by governor pressure, the vehicle speed, and throttle angle. So at low speed the governor pressure is low and the shifts are soft and as speed increases, governor pressure increases and the shifts get harder. Which is what is happening. The 1-2 is weak, the 2-3 is better, and the 3-4 is normal because it's controlled by the PCM. There may be some way of making the low speed shifts better, but it's going to take a specialist to do it. There are 4 different governor pressure curves depending on throttle angle and vehicle load involved. Can they possibly make it any more difficult? Sheech! Just give me an old A500 TorqueFlite will you? I can live with a 3-speed.
On the rebuilt, I would start with a simple band adjustment. Likely things have burned in a little bit. Be willing to bet it's recommended on a new rebuilt. My 150k re was doing that when I got it, I was like whoa! So did that, cleared it right up. That and a dozen fluid changes. Oh its a bit clunky now but highly reliable still at 210k.
There's only 4K on it now and it's been doing this since day 1. I thought it would get better, but it hasn't changed at all. This is why I was looking to do something about it, but Palladino wants the check with the rebuilder before doing anything and it's just not one of his priorities. I'll bet I can kick him in the *** by asking him for a phone number so I can check on it.
I spose if it's under warranty you would want to do that first. My guess is it wouldn't void anything but who knows.
Mine was loose between 1and2 and 2 and 3. This was 4 years ago when I adjusted them last. Amazingly it's smooth as silk now under most conditions. Shifts great. If I really hammer on it, it will slip , but at this point it is totally fine to drive around. With nothing invested I intend to not fix it if it isn't broke.
