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TH350 modulator

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63willys

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So, I found out that the PO had attempted to JB Weld the little ear which holds the retaining clip for the vacuum modulator. How it got broken is long distant history, I guess. The fix held long enough for him to get the car sold. Now I have the modulator held in place with 80 lb. fishing leader wire. The local transmission shop wants BIG $$$$ to replace the case (and as long as it's out of the car, we might as well do a rebuild, etc.) I'm planning to fabricate a bracket that I can bolt on to do the job and save myself downtime and of course, $. Anybody ever done this and have pictures?
 
That will never work.
TH350s require 150 lb leader wire...............

There are lots of folks here who are more familiar with those things than I am.

Greg Ducato comes to mind, but there are others.
Somebody has probably done it already.

I thought I remembered the modulator screwed into the side of the transmission....
 
find a good welder and have them tig weld the area backup and redrill/tap the hole. good to go with new bolt.

makes me sick to hear of people saying case is shot need new for a tiny problem /easy fix. kind of like broken off bell housing ear corners . if you got it a good welder can tig it back on and be just fine.

DO NOT USE SPOOL GUN on a mig welder it wont hold.

1 time had a 3500 chevy van come in broken bell housing . the boss had some joe blow spool gun weld it after i said it wouldnt hold. 3 days later it come back in on the hook/tow truck. :whistle:

he asked me to take the tranny and get it fixed . i called my local guy and took it over. 30 min later back at shop. 20x better. and best part is its still going for all i know. used every day as a delivery / sales route box truck. :haha:
 
If you don't have enough room left on the tab to move over slightly and drill and tap another hole, (it can be smaller, like 1/4" ) then I would use a bracket from an extension housing bolt to retain it. I think I have one of these here at the shop if you need one let me know.
 
Greg Ducato said:
If you don't have enough room left on the tab to move over slightly and drill and tap another hole, (it can be smaller, like 1/4" ) then I would use a bracket from an extension housing bolt to retain it. I think I have one of these here at the shop if you need one let me know.
Click to expand...
If I understand you correctly, a bracket from an extension housing bolt to the modulator base is exactly what I need, and was planning to fabricate. If that's what you have, let's make a deal! Thanks.:bow:
 
Seems to me I remember selling a used Gm tranny at the junkyard,that had a allen head set screw put in the case where the modulator goes into it,because the bolt in the hole for the modulator bracket got snapped off somehow...looked like someone drilled & tapped it and used the set screw to keep it in place,rather than try getting the busted bolt off......dont know how it panned out,we sold it cheap because of that "defect",told the guy no refunds!...it was in a running car we used as a torchwagon for awhile,so we assumed it worked OK....
 
Greg, only slightly off topic.

At my age, I keep checking to make sure I have not gone any crazier than usual. So, when I have a fairly clear memory of something that does not seem to be so, I tend to worry.

I guess it was about 40 years ago, and if you don't think that makes me feel old..., a friend of my father had a GM brand truck.
He started having simultaneous problems with the idle and transmission.

Turned out, the modulator hose had come off the transmission. He stuck it back on, and it came off again later.
He trimmed off the end and it held for a while.

Couple of times, I was recruited to do it.
When the hose got too short, he went to the dealer for a new one.
They told him what the problem was, a pinhole in the diaphragm and sold him a new modulator and hose.

So far, so good. I have diagnosed that same problem for others over the years.

Here is the part that worries me.

I can very plainly remember sitting on the ground next to the truck while they put in the new modulator.
I was holding either the old one or the new one looking at it. It had the hose fitting on one side, and what looked like a pipe fitting with a plunger sticking out on the other.
It simply screwed into the side of the transmission.

Everything I see nowadays, is a smooth tube with an O ring held in by a keeper.

Did GM ever use the other style modulator, or is this some kind of weird false memory.

And if so, am I really typing a message on a forum called K5, or am I sitting in a room somewhere drooling on myself making typing motions with my fingers???

Inquiring, maybe damaged, minds want to know...........I think.....
 
I think I remember seeing a HD version of the 350 transmission with a side mounted modulator, so no, you aren't going senile yet. I have an increasing case of CRS myself, at 65 years young.
 
Thanks folks, that makes me feel better. As for it being a powerglide, would not doubt it. It was a long time ago.

I never knew what type of transmission it was, just somehow figured it was a th350 because they were so common..

EDIT:
Yepper, thats it. I should have gone to RockAuto to start with. Looked for a modulator for a 1968, at the bottom it listed a powerglide and that was the modulator I remembered.

Slightly different from my memory, but certainly close enough given the number of years.

Thanks Folks.
Guess I still got it................... Sure thought that last round of shots would gotten rid of it though..........

powerglide.jpg
 
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Some Fords had threaded modulator valves too Fordum,your not going mad....:D ...the "heavy duty" 350 trans with a side mounted modulator sounds like a TH375,which is has a TH400 style case, and a TH350 output shaft spline count,and the modulator is in the same location as the TH400..I've seen only two of those,one was in a 70's Caprice wagon that was a hearse,with a 400 SB!..other one was in a late 70's G-30 motor home van...
 
diesel4me said:
Some Fords had threaded modulator valves too Fordum,your not going mad....:D ...the "heavy duty" 350 trans with a side mounted modulator sounds like a TH375,which is has a TH400 style case, and a TH350 output shaft spline count,and the modulator is in the same location as the TH400..I've seen only two of those,one was in a 70's Caprice wagon that was a hearse,with a 400 SB!..other one was in a late 70's G-30 motor home van...
Click to expand...
Thank God! I thought I was ready for the rubber room....
 
Update

Many thanks to Greg Ducato for sending me the custom modulator bracket. It was intended to bolt on at the extension housing to hold the modulator, but since my rig has an Advance Adaptor connected to a Willys D18 TC, it couldn't be done. So, what I did was reverse the direction and attach it with clamps, straps, and a long 1/4 20 bolt. Rube Goldberg would have been proud. Now for an oil change, add some ATF, and I'm ready for the road! Thanks again for all the help here.

Yeh, right. Like I'm the only one here old enough to remember Rube Goldberg!
 
I'm old enough to know who Rube Goldberg was...he inspired most of my exhaust systems and "booty-fab" repairs on my many mechanical things!...:whistle:..
 
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