42RH total rebuild - soft'ish 1-2 and 2-3 flare under powe

I recently finished a rebuild of a A500/42RH. (OD+LU)

TransTec overhaul kit / new steels and Alto clutch plates.
TransGo Reprogramming Kit
Billet accumulator piston

Now during operation I've found a couple of things;

- Engagement from P or N into 1st gear feels fairly normal, maybe a tad soft considering the TransGo kit being installed.

During normal driving;
- 1-2 shift feels ok, 2-3 shifts feel nice and firm.
- shifting to OD comes in nicely, Lockup is nice and solid. (Both manually controlled with dash switches)

During firm/hard acceleration;
- 1-2 feels soft
- 2-3 very noticable flare up in the engine rpm. As if 2nd gear/band releases to quickly, or starts slipping as soon as the shift-operation is started.
- shifting to OD comes in nicely, Lockup is nice and solid. (Both manually controlled with dash switches)

Adjusted the front a quarter tighter to 1-3/4 turns out, from 2 turns. Helped some but not much.

When accelerating hard in 1-2 and get off the throttle very briefly when trans shifts to 3rd, all feels fine.

Engine in front of the transmission is a 360ci with a mild (Comp XE256) cam. Nothing serious.
Transmission holds WOT-power in all gears, no slip, leaving me to believe this is a band/accumulator issue perhaps?
There's a 3.8 band lever on the front band. I'm thinking a 4.2 lever would provide a little more clamping force?

After support contact with TransGo, did a light mod to the TP-linkage. Slight improvement but not much.

Accumulator port-pressure is 75psi in D and both manual 1 and 2.
Pressure rose when upping the rpm but couldn't test max pressure increase because of single handed in-car operation.


Any tips, things to check / look up?
Hope to be able to solve this with transmission in the car as it's a bear to remove (A-body + headers).

The 1/2 shift under acceleration may be normal, depends on the torque converter, the looser the softer, the tighter the harder. The 2/3 flare is most likely the band releasing to soon. I'm not a fan of the TG kits in the OD transmissions. Use a flat blade screw driver and pry the band apply lever down and see how much gap you have between the lever and the servo. You only need about 1/4" minimum. So start there and adjust looser if you get a little binding.

If you installed the orifice restrictor in the case, remove it. (thread a sheet metal screw into it an remove with claw hammer or pry bar) This will stop the delay of the clutch apply on the 2-3 shift..

I didn't install the tapered orifice, thinking I would reuse the original vb-plate. But later on during the build I did decide to use the TransGo supplied vb-plate because the original vb-plate had too much damage where the check-balls sit.
TransGo mentioned the restriction is (also) present in their vb-plate so I might have to look up where it is and open it up some.

The 2-3 shift flare is because the front band is releasing faster than the front clutch is applying. Where you say you have a soft 1-2, that is the front band applying to stop the spinning front drum. What springs did you use in the front servo apply piston and how many springs did you put in the front clutch? Do you have a way to measure your line pressure?

Well look whose back!!!

Kevin

A TransGo kit with a plate? What's the kit number?

JohnRR
My oil pressure-gauge only goes to 100psi so couldn't do other pressure tests.
Followed the TransGo manual to replace the stock servo spring and install the supplied one.
Don't recall the number of springs, imo the stock amount. This rebuild was spread out over roughly 3 years.
Transmission and OD-unit were build some 3 years ago and I just finished the valvebody mods right before taking the transmission in use.
I took a fair number of pics during the build but of course never enough because of greasy hands.


John Kunkel
Will have to look up the kit.nr on box in the garage.
It came with a manual from 17 sept 2014.
TFOD-HD2

I would be surprised if you had more than one spring in the front drum.

Yeah, 42RH is a single spring like a 904.
The front clutch restrictor doesn't do a lot in my experience. The O/D valve body plates typically have two holes in the front clutch apply port with a check ball in the valve body. I believe that was there to soften the shift into reverse. If you used an aftermarket plate with a single hole and left the check ball in there that could be part of your problem. Chuck that ball in to your junk drawer.

Thanks , I don't have experience with the 42RH , I thought it had a front drum setup more like the 46/47 (727 based) forgetting the 42 is 904 based.

carry on

Prior to this rebuild (3+ years ago), I have been working on a A518, and this clouded my memory now about the 'number of springs'.
Went back looking at pictures I took of this A500-rebuild, trying to refresh the memory when it came back to me again... lol




The old vb-plate had extensive damage where the check-balls had been 'hammering' away at the plate. Some almost made it through the plate. This led me to use the TransGo supplied vb-plate in the kit.
Pics below;

That 5th port from the left where the two holes are, is the front clutch apply port. This arrangement would have had a check ball in there. If you left it in, remove it.

The two holes are for the rear clutch. Never seen any Chrysler trans with a ball for the front clutch.

Just two in some apps. for the L/R servo and some for the rear clutch.

Seems some people used to complain how hard our transmissions went in to drive or reverse.

Because of the 2 balls in the rear servo we had the infamous “snow plow truck” failures.

Yes, that is correct, my mistake.

Could anyone show what hole(s) in the vb-plate to enlarge to get rid of the 2-3 flare up?

I like to open up the transmission just only one more time, as it's a bear to get to the topmounted levers on the trans in the car.

This diagram calls for drilling to .110" but I would drill both "A" and "B" to 3/16". 2-3 to 1/8".

Thanks John.