Too slow to low

[Raider L]

@Matt69olds,

And whoever else who is well experienced in TH350's. I just had my trans rebuilt. I can't give you any details whatsoever about what they did or what parts they put in. But they came highly recommended because of all the race trucks, cars old and new, and hot rods, custom purpose built vehicles they deal with those trans all the time. I felt they knew what they were doing especially since my truck is far from stock even though the trans is stock.

So here's my question, it's shifting too early from 2nd to 3rd, like at pulling away from a stop under light acceleration it's in 3rd gear at 20 mph. I've driven this truck since '81 and I have paid close attention to how the trans works and I like it going into 3rd at about 24 maybe 26 mph, and with a bit more acceleration maybe 28 but NO later. Now I know that it also would shift to 3rd if I was going real slow like as if you were looking for an address and were just slipping down the street it would shift to 3rd at 22 mph. I know the trans is set up to do that as well. That function is okay. I wouldn't want to still be in 2nd driving slow at 30 mph because I'm not far enough into part throttle yet. It decelerates okay, like it should.

And under moderate acceleration, like from a stop, you are pulling out into traffic that is at street speeds of 35 to 45 it would shift to 3rd at I think...28 mph, maybe 30 but it would take moderate acceleration part throttle to make it do that, you know? The way it's set now even under moderate acceleration it shifts to 3rd at 20 to 21 mph, no matter.
I know from hearing people on this site and from what I've read in magazines the TH350 are these soft and easy shifting transmissions and they are made that way, and a lot of people don't like that about the 350's. It's just what I've gotten used to and it's alright with me. You know everyone is different like that. I don't care for a hard shifting trans when I'm going down my neighborhood street at 25 mph, you know? I don't ever drive down them at 25 I always drive at 30 or maybe even 33. Never the less, I called the trans shop that rebuilt it and the guy said turn that screw in the modulator valve, "...a couple of turns." I made some comment and that was the end of the call. I knew to do that to the modulator valve but just to make sure that was all, that's why I called in case I needed to bring it back over there.

My other question. How much will "a couple of turns" produce in mph? And which way, in or out, I think "in"? What will a quarter turn, a half a turn, three quarter, etc. produce in mph change? When you all were helping me last year, the trans was to messed up for any changes to be working right, that's why I never fooled with it in that way. And that's why I told you all I've never messed with transmissions at all.

And I have read about the different springs that can go inside the thing, and damn it my memory, it's got the domed cover with the wire clip on it, and it's on the left side near the back kinda, that has the fly weights inside of it, I can't remember what it's called. Can't some gear shift timing be changed there as well? Help me out here, What's it called and would I need to fool with that?

Or playing with that little screw in the back of the mod. valve will be all I need to do?? And also, will changing the screw setting change all shifting, 1st, 2nd, and 3rd or just 2nd to 3rd?

 

[82sbshortbed]

From what I've seen on YouTube it's all preference and feel. Trial and error. Turn it some and take a test drive, then repeat. I'm gonna put and adjustable vacuum modulator on mine as soon as I get the new rear end in and see how it shifts.

I like a hard shift and have a shift kit in it. With mine at moderate throttle it shifts into 3rd pretty quick too. I don't think it's a problem because when I stand on it it shifts around 5k into 3rd.

Adjust your kick down cable? I don't know near what Matt knows about them. Maybe he'll chime in.

 

[Matt69olds]

You can change shift points 2-4 mph either way buy turning the screw in or out. In make the shift later, out makes it earlier. If you need more of a change than that, then you need to play around with the governor.

Unless the governor was replaced during the rebuild, new clutches/etc shouldn’t make a difference in shift points. Some shift kits include a slightly stiffer 2-3 shift valve spring, installing the spring will make the shift slightly later.

Before doing anything, ask the shop what was damaged and replaced during the overhaul. Just to cover your ass, ask the shop about adjusting the modulator. Some shops might get pissy if you adjust things without running it by them.

 

[Raider L]

@Matt69olds,

Thanks. That's what I thought but wanted to run it by you before I fooled with it. As a matter of a fact that was the first thing I did was to call the shop and ask them about it and whether I should bring it in. He said, no that I could adjust the modulator valve screw myself to get it to shift later, etc. But that was one thing that I kinda was bothered by and that was I didn't get an itemized list of all they did. All I got was like a register receit from my card charge. I had to ask for a piece of paper with the different charges for whatever and even that was skimpy. When I asked him about what all needed replacing he said, all of it. When I queried him further he just said it was all worn out. It's been to long now to get any more details about the work because it took two and half weeks to get the truck done because of all the cars and trucks that were in there I was surprised I got it back that soon!

But I wanted to ask you when I do change the screw setting, will it affect all shift points or just 2-3? Oh yeah, how many, or what part of a turn do I need to turn the screw, i.e. 1/2 a turn equals 2 mph or what? Or one whole turn equals 2 mph or what?

 

[Raider L]

@Matt69olds,

Yeah, the "governor"! That's what I couldn't remember the name of. That I have read a lot about. It's got a plastic gear on the end of it and from the picture in the article there were a whole bunch of different springs you could replace and different weight fly weights as well you could try. I don't really want to get that involved in it so if adjusting the mod. screw will get it shifting where I'm used to it doing that will be enough. So why would there be a time where they would need to change the governor out anyway? Is that a normal part in the overhaul process to replace? Or would they just check it and if it's okay they just clean it and put it back in?

 

[Matt69olds]

If the plastic gear is worn, most shops will simply install a good used govenor instead of taking the time and expense to replace the gear. The plastic gear is designed to be the weak link, if the governor stops turning in the case, the gear is designed to strip instead of chewing up the case.

The shop might replace the governor if the valve inside won’t move freely.

At most, you can change shift point 4mph. If that’s not enough of a change, a governor swap is the only other option. Get another governor to experiment with, that way if you have problems you can reinstall the original.

Modifying the governor isn’t very hard, it’s just time consuming. Depending on how picky you want to be, there are hundreds of different combinations of weights and springs you can try. Take detailed notes, make one change at a time until your happy.

 

[AKguy]

This site has a couple good, short articles regarding the modulator and the governor.

http://www.indianachevelles.com/ind...karticles/169-article-th350-400-governor-mods

 

[Raider L]

Thanks guys!! When it comes to automatic transmissions I need all the help I can get. I like fooling with complicated machinery, my gosh I was a aircraft mechanic for seven years in every inspection phase and repairs there is including wing bolt changes and engine changes. I did all the welding repairs both airframe and power plant, on twenty two aircraft by myself. I was the welding dept.. I had to do repairs with the FAA inspectors standing right there whenever I had to do the jet engine exhaust duct welded repairs. Because we were the only large commuter airline that did those kinds of repairs in the field, in the whole U.S.. We even had Grumman Mfg. tech guys come and approve pressure dome repairs, pressurized aircraft, that no one ever did in the field before due to the extreme complication of the repair, on big ass G1 twin turbo prop passenger aircraft. It was fun! Fortunately we had a retired U.S. Airforce chief master sergent who ran the sheet metal dept. at the air base across the river where I live. He and I were the only two people authorized to do that repair.
But when it comes to an automatic transmission it scares the crap out of me. I just know I'm going to break the dang thing.

 

[Raider L]

@AKguy, @Matt69olds,

I went to that site, AK. It was okay. But I typed into my computer, "What shift point change is there with governor spring change, TH350" And it took me to the B & M site where they have a governor recalibration kit that has several weights for outer and inner flyweights, and several colored springs. It also had a whole instruction sheet and explained what the governor was for and how it worked. What your site AK, said was that if rear end ratio has been changed then the governor is out of calibration. Well, I didn't know that!! Also it said the calibration process is trial and error, I figured that. The B & M site also interated that if rear end ratio has been changed the governor is out of calibration. It said that I need lighter weights for later shifts, or a spring change can also affect the shift point.

I have no idea what was done to the governor other than the trans was overhauled.
The problem is my physical condition has gotten so bad what with crawling under and out from under the truck that I just can't be doing it more than one or two times and I'm finished!

So I'm just going to try to get my son to help me get the truck up and I'll try to mess with the modulator valve first and maybe that will get the trans where I need it to be. But that thing about the rear end ratio change worries me. I drove it for many years and even raced it a little right after the truck was rebuilt and the trans shifted what seemed right on. It wasn't early or to late at WOT. So If the trans shop did anything at all to the governor it should be the same. But the other day I got on it with moderately heavy acceleration and it still shifted to 3rd at 20-21 MPH. Now I don't know if that's the modulator valve or the governor or both!

Now, there was some mention about the down shift cable in my TH350 that needed to be adjusted. I may look at that later. I can mess with it, but at least I know it's been overhauled and not in the terrible shape it was in. So whatever I do won't cause it to do what it was doing before. At least I hope it won't. If I do mess something up I know that I've got the time and money to get in the shop and get the dang thing right.

 

[Matt69olds]

No kickdown cable changes things big time!!!

You will never get the WOT shift points right is the cable isn’t connected. The trans will always short shift with it unhooked.

Unlike a 700, a 350 doesn’t depend on the kickdown cable to control line pressure. So you won’t damage the trans with it unhooked.

The kickdown cable pull should max out at full throttle.

 

[Raider L]

@Matt69olds,

I will look at the cable tomorrow and I might even get my wife out there and have her floor it so I can check if they got it right. Of course I will look when I open the hood if the cable is even hooked up. Gee, I sure hope they weren't in that much of a hurry to get it out the door after they had it for two and a half weeks, and $1400 dollars to overhaul it. The last time I called them to check on it they said they were finishing up on it but they weren't going to be able to test drive it to adjust everything because of the condition of the front end. I agreed that I didn't want them to drive it in the shape it was in. So I told them what I had planned was to have it towed over to the shop that was going to do the suspension, and when they were done I was going to have it towed back over to them and they could drive it all they wanted in order to get the adjustments right.

Then when I called him a couple days later to tell him the tow truck was on it's way what he told me kinda surprised me. He said, "That's okay we adjusted it and it won't need to come back over here." I thought it needed to be adjusted and he couldn't do it unless it was drivable? So I just said "Okay".

Well, Matt what adjustments would have been needed? The modulator valve? The governor? The kick down cable? All the above??

I'm telling you the place was so over loaded with cars and trucks needing to be worked on I don't see how he could do it all. I figure that they had all the big work done, and they had put that Lokar shift rod in already, and they just needed to get it out the door and weren't going to fool with it anymore. I wish I knew someone who could take a look at it. I'm just not physically able to do it anymore. Even just last year the difference is big how my body has gotten so much worse this year. That's why I say I'm going to rest up some and get some pills down me and get my son to help me and get under the truck and fool with the modulator valve first. But like I said I got about two times under it and that's going to be it for me. That's why I may call around and see if I can find someone who can help me.

 

[Raider L]

@Matt69olds,

Last night I finally remembered what my original rear gear was and it was a 3.47:1. I wanted to put that Richmond overhaul kit in it but I remember they didn't have a 3.47, but they did have a 3.50:1 so that's the one I put in. Do you think that little of a change would require the governor to be recalibrated? I don't know the numbers of a gear ratio that would require a recalibration but don't you think with as little a change that I made, just leaving the governor alone would be okay?

I read, and read last night about governors and modulator valves and adjusting kickdown cables until I was blurry eyed. One of the things I took away from all that was about the only time the governor needed to be recalibrated was if you were going from a 2.80 highway gear to a 4.10 gear. Now, that I can see. Even like a 3.23 to a 4 something would need a recalibration. I don't think I fall into that category. So I'm just going to reset the modulator valve.
I just wish I had some quick way to get my truck up without having to jack it up with a floor jack. And no, I don't own a set of ramps. And no, I'm not going to buy a pair just to get under the truck one, or two times. So we'll see how it goes. I just want it to drive like it did for the last twenty five years. And if I can get twenty five years again, I don't think I'll live that long, but at least I would have been able to have fun with it until then.

 

[Raider L]

@Matt69olds,

I got my son to help me jack the truck up just high enough to get under there. I first turned the screw 3/4 of a turn. I read the factory maint. manual and it said 1/2 to 3/4 of a turn adjusted the modulator valve. Well the guy from the trans shop said, "...a couple of turns.". So I got the truck down and drove it and it didn't make any difference at all. I just drove it normal no WOT. It shifted at 20-21 mph. So I came back and my son jacked it up, this time I turned it to one full turn. Drove it, no change. Came back, this time I jacked it up and turned it another full turn. That makes two full turns like the trans shop guy had suggested. Drove it...no change! So, in my limited experience I would say it's the governor and I can't imagine what the trans shop did to it to make it like it is now. Hell, it was shifting fine before the rebuild, it was just shifting messed up but I could still get on it and it would whind out the gears. It won't even begin to do that now.

 

[Matt69olds]

Final drive ratios have a big influence on shift points. If the gear swap was done before the trans overhaul, it should shift the same after the rebuild.

As you discovered, the modulator has no affect on WOT shift points. Modulator adjustment at most can change 2-4 mph.

Something was changed during the overhaul. Either the kickdown adjustment is different, the shop swapped valve bodies/govenors, or maybe the converter they used is much tighter, or a combination.

Did you verify the kickdown cable is connected and adjusted correctly? The trans is always going to “short shift” at WOT if the cable is connected.

 

[75gmck25]

The TH350 kickdown cable is a five minute adjustment and requires almost no tools.

The kickdown cable retainer is square and is inserted into the bracket next to the throttle cable . If you look at the square retainer you will see that the top has a separate tab, which is the top of a locking piece that slides up and down.

- use a screwdriver and/or pliers to gently pull that slider up . If nobody has moved it lately it might be stuck in dust and dirt.
- have someone go in the cab and push the pedal all the way to the floor and hold it there
- with the linkage still at full throttle, push the tab back down to lock it in place
Kickdown adjustment is done.