Repair-It

I re-read my other transmission thread where I did fluid and band adjustments. Even though I acknowledged the existence of a TV cable, apparently it didn't really sink in. This is supposed to be an electronic transmission (the "E" in 42RE, as opposed to 42RH which is hydraulic). My brother in law called me on my way to Boston on Friday and brought up the 42RE in his JGC. He started talking about the TV cable and I'm like...how does that have a cable? It's electronic. In GM land, when they updated the 700R4/4L60 to electronic controls starting in 1993 in trucks, the TV cable completely went away (same for the vacuum modulator on the fully electronic 4L80E in 1991). Dodge converted to "electronic" in 1993, too (though introduction of overdrive wasn't until 1989) but they kept the cable. Weird, eh?

So as he was talking about the TV adjustment changing shift behavior (on an electronic trans) I'm like....wait, WAIT. Do I have this adjustment on mine?? I must. Could it be responsible for some of the bad shift timing I've been complaining about the entire time I've owned this truck?? It got a rebuilt trans at 105k, what are the chances the TV cable wasn't adjusted properly? Pretty high actually. Soooo....

Yesterday I went out to look. Since this is a simple 90s vehicle, I could get to the adjustment after simply opening the hood. Here it is: Adjustment is kind of the opposite of the GM way to do the 700R4. On the GM ones, you set the cable so at WOT, the TV also goes wide open, so they match. However there is a "hack" on those where you can just tighten the adjustment, then smash the throttle, and the plastic detents skip to where it is supposed to be. This is not GM sanctioned and while it will get close I do not think it is correct. The good news is, GM gives you a spring loaded button, after pressing you can just move the cable sheath forward or backward.

On the 42RE, there is a plastic C clip that you remove and that's what holds the sheath in place. Cheaper design and the plastic seemed to be fatigued but still holding. Not just a cheaper design though because on the 700R4, you can fairly precisely adjust the TV forward or backward to fine tune the adjustment. On the Dodge, when you pull that plastic clip, the adjustment kind of just pulls itself to one limit and you have to readjust.

OK, so what you do is remove the clip, disconnect the end of the cable from the throttle bracket, and pull the adjustment until it aligns with the center of where it could clip onto the throttle, at idle. So basically the adjustment is done at idle, instead of WOT on GMs. Same idea.

Anyway, I found that the adjustment was set too tight. So at idle, the TV was being pulled. This is why the 2-3 shift point, particularly at lower throttle/speeds, always felt so screwed up. Because it was. I spent probably 20 minutes trying to tweak the adjustment and doing test drives. Here is the result.

The WOT 1-2 is still firm and seems fine (softening the TV adjustment on a 700R4 will impact all shifts especially if the TV can't go fully open at WOT). Shifts around 4800rpm. So far so good. The 1-2 part throttle seems maybe a little earlier but overall the 1-2 business seems "good" though that wasn't where I had an issue. Onto the 2-3.

This adjustment definitely influences the 2-3 more. The 2-3 behavior from a shift point aspect has improved. It still does some 3-2-3 business at certain speeds and throttle positions but overall seems better. Getting into 2nd at higher speeds now requires some heavy throttle. This is fine. It has a lot of throttle travel and I think it is normal to require the throttle to reach what would have been a kickdown detent toward WOT. However, the firmness of the 2-3 is still unsatisfactory as it was before. If anything it may have gotten a touch softer. It will do a WOT 2-3 around 4800rpm.

Didn't really play with the 3-4 but it seems fine and I think that shift may be 100% electronic anyway.

TL;DR: I think the shift points make it feel more like a real transmission now, even though my assessment is this transmission is too light duty for the power and weight of this truck (seems to be the highest stress application of the 42RE, if mine had either the 5.9L or 4WD, it would have the 46RE - not sure about long bed, so maybe it could get slightly worse in 2WD since mine is the short bed). Reducing some of the 3-2-3 behavior is probably good for the transmission but other than that, I don't think anything else I did will enhance its life, either. Worth doing either way.

Bonus fact: The overdrive on the original A500/42RH was literally bolted on as the tailshaft. It continues to perform that function in the 42RE but the controls were simplified.

https://www.bigblockmopar.nl/2018/08/a5 ... d-project/

The A500 (or also known as 42RH) transmission is based on Chrysler’s ‘904’-smallblock transmission. The A500 has an overdrive-unit added to its housing, and a stall convertor lock-up function. The overdrive increases the output-shaft of the transmission by 0.69.

Note the part about overdrive being contained within the extension housing and also the fact that the 3-4 shift is fully electronically controlled: https://en.wikipedia.org/wiki/TorqueFli ... 42RE/44RE)

An extension housing mounted (New Process built) overdrive unit was bolted to the rear of the case to provide a total of four forward speeds; the extension housing and its internals interchange with the 46-48RH/RE (A518/618) - when overhauling the overdrive unit transmission rebuilders usually would use replacement parts from the A518/618 overdrive section since the A500 internals are light duty e.g. number of friction discs and thick pressure plates. The overdrive housing (RWD/2WD) uses an output shaft yoke commonly shared with the A727 and its later derivatives except the A618/48RE.

It was made by New Process!

To drive the point home, here is the tailshaft which is also called the overdrive extension housing:
https://globaltransmissionparts.com/a50 ... using-2wd/

The 700R4 was an integrated 4-speed automatic in like 1982 and the THM200-4R was 1981. I think the 200-4R has some relationship to the Turbo 350 (it was in fact designed to bolt into where a Turbo 350 previously was, unlike the 700R4) but it certainly didn't have a bolted on OD unit. I don't believe either the 700R4 or 200-4R were a "Turbo 350 with overdrive." The 4L80E was electronic in 1991 and while it actually is very similar internally to the Turbo 400 (same 1-3 gear ratios even), the overdrive was all internal and developed by GM. Chrysler bolted an OD unit on for 1989, ~8 years after GM introduced TWO integrated 4 speed automatics. Just saying.

Initial engagement into R or D doesn't slam now. This makes sense because the throttle valve was a little open even with no throttle before.

Overall I am glad I made the adjustment.

I still have to laugh at this transmission. TV cable, band adjustments...you'd think this was 1975.