help with a TH350 - The 1947 - Present Chevrolet & GMC Truck Message Board Network

JesseSimon · 07-18-2010, 12:08 PM

A few weeks ago I bought a 77 Silverado. Great truck, needed some minor stuff. Got a TH350 in it. Good trans but it was leaking all over the place and shifting hard. I replaced the modulator (wrong one was on the truck), filter, fluid, pan gasket, and swapped out the leaky rear seal. Shifts great now.

I had a hard time getting the new seal in and ending up getting a little more forceful with it than I would have wanted too. It still leaks, more than before actually. I have bought another seal and am about to head out to mess with that. This time when the guy at Autozone asked if I wanted just the seal or the one with the bushing, I said I'll take the bushing.

My two questions are:
1) Any tricks for getting the seal in smoothly?
2) Where does this bushing go? This isn't my area of expertise so don't rib me too bad haha! Its like an 1.5 inch round 1.5 inch long tube with grooves in it........

JimKshortstep4x4 · 07-18-2010, 01:19 PM

The bushing goes into the housing first and then the seal. If you have the correct driver for the seal and bushing it goes pretty easy. The old bushing and seal must be removed first and there is a special puller made for the removal of the bushing.

Jim

JesseSimon · 07-18-2010, 07:28 PM

Thanks for the help so far. I got the truck lifted up and started inspecting things and now I am not sure its the seal that is leaking. Is it possible for fluid to be leaking from the speedo cable?

Sinister · 07-18-2010, 07:30 PM

Quote:

Originally Posted by JesseSimon

Thanks for the help so far. I got the truck lifted up and started inspecting things and now I am not sure its the seal that is leaking. Is it possible for fluid to be leaking from the speedo cable?

Yes.

charx2 · 07-18-2010, 07:34 PM

Quote:

Originally Posted by JesseSimon

Thanks for the help so far. I got the truck lifted up and started inspecting things and now I am not sure its the seal that is leaking. Is it possible for fluid to be leaking from the speedo cable?

That's where mine is leaking from, it's the O-ring I need replacing I think.

Quote:

Originally Posted by JesseSimon

It still leaks, more than before actually.

Story of my life!

JesseSimon · 07-18-2010, 07:53 PM

I'm pretty sure thats my culprit then. I will probably just pull the tailshaft off and replace all seals involved, And the speedo cable, it feels loose and won't tighten up and its about 10 mph off

charx2 · 07-18-2010, 08:15 PM

That's where mine is leaking. Take off that nut and it's like a little bullet, check the o-ring. It houses some gears which you can replace to slow down your speedo...

charx2 · 07-18-2010, 08:17 PM

Not saying that's what it is, but it's worth looking at.

68K30 · 07-18-2010, 11:35 PM

Take the tail-housing to a local trans shop,they have the correct tools to install the bushing and seal. It's an easy job, should be fairly cheap if you buy the seal and bushing from them and they will also have the two seals for the speedo adaptor and the square cut O-ring that goes between the case and the tail.

Good luck
Bill

07-18-2010, 12:08 PM	#1
JesseSimon Asks alot of questions Join Date: Feb 2009 Location: Rogers, Arkansas Posts: 231	help with a TH350 A few weeks ago I bought a 77 Silverado. Great truck, needed some minor stuff. Got a TH350 in it. Good trans but it was leaking all over the place and shifting hard. I replaced the modulator (wrong one was on the truck), filter, fluid, pan gasket, and swapped out the leaky rear seal. Shifts great now. I had a hard time getting the new seal in and ending up getting a little more forceful with it than I would have wanted too. It still leaks, more than before actually. I have bought another seal and am about to head out to mess with that. This time when the guy at Autozone asked if I wanted just the seal or the one with the bushing, I said I'll take the bushing. My two questions are: 1) Any tricks for getting the seal in smoothly? 2) Where does this bushing go? This isn't my area of expertise so don't rib me too bad haha! Its like an 1.5 inch round 1.5 inch long tube with grooves in it........ __________________ MY STABLE: '66 C10 LWB turning it into a shortbed stepside '77 LWB (my daily driver).....oh its a FORD ahhhhh! '07 MAZDA 3 (the wife's ride)

07-18-2010, 01:19 PM	#2
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	Re: help with a TH350 The bushing goes into the housing first and then the seal. If you have the correct driver for the seal and bushing it goes pretty easy. The old bushing and seal must be removed first and there is a special puller made for the removal of the bushing. Jim __________________ 1971 Shortbox step side 4x4, 350 sbc, 3:07 rear end 1965 Impala SS 400 sbc, Muncie rock crusher 1966 Impala SS 396 bbc, TH 400 1969 El Camino, 350 sbc, TH 350 1971 Snowplow built on a Blazer frame 1972 GMC Short bed, stepside, TH 400, 427 BBC

07-18-2010, 07:28 PM	#3
JesseSimon Asks alot of questions Join Date: Feb 2009 Location: Rogers, Arkansas Posts: 231	Re: help with a TH350 Thanks for the help so far. I got the truck lifted up and started inspecting things and now I am not sure its the seal that is leaking. Is it possible for fluid to be leaking from the speedo cable? __________________ MY STABLE: '66 C10 LWB turning it into a shortbed stepside '77 LWB (my daily driver).....oh its a FORD ahhhhh! '07 MAZDA 3 (the wife's ride)

07-18-2010, 07:53 PM	#6
JesseSimon Asks alot of questions Join Date: Feb 2009 Location: Rogers, Arkansas Posts: 231	Re: help with a TH350 I'm pretty sure thats my culprit then. I will probably just pull the tailshaft off and replace all seals involved, And the speedo cable, it feels loose and won't tighten up and its about 10 mph off __________________ MY STABLE: '66 C10 LWB turning it into a shortbed stepside '77 LWB (my daily driver).....oh its a FORD ahhhhh! '07 MAZDA 3 (the wife's ride)

07-18-2010, 08:15 PM	#7
charx2 Registered User Join Date: Apr 2010 Location: Mobile, AL Posts: 365	Re: help with a TH350 That's where mine is leaking. Take off that nut and it's like a little bullet, check the o-ring. It houses some gears which you can replace to slow down your speedo... __________________ ----------------------------------------- My 67 c10 Thread. http://67-72chevytrucks.com/vboard/s...d.php?t=409192 Last edited by charx2; 07-18-2010 at 08:31 PM.

07-18-2010, 08:17 PM	#8
charx2 Registered User Join Date: Apr 2010 Location: Mobile, AL Posts: 365	Re: help with a TH350 Not saying that's what it is, but it's worth looking at. __________________ ----------------------------------------- My 67 c10 Thread. http://67-72chevytrucks.com/vboard/s...d.php?t=409192

07-18-2010, 11:35 PM	#9
68K30 Registered User Join Date: May 2007 Location: Pennsylvania Posts: 99	Re: help with a TH350 Take the tail-housing to a local trans shop,they have the correct tools to install the bushing and seal. It's an easy job, should be fairly cheap if you buy the seal and bushing from them and they will also have the two seals for the speedo adaptor and the square cut O-ring that goes between the case and the tail. Good luck Bill



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