Auto transmission trouble
Thread Starter
8th Gear
Joined: Aug 2018
Posts: 8
Likes: 3
From: Mount Airy, NC
Auto transmission trouble
My 74 has a problem with either the torque converter or the transmission, I don't know which. After startup the car will back up about 10 feet then act like I put in the clutch, after 2 seconds it will start moving again. It will occasionally wait a few seconds to move at stop lights as well. It also leaks to the point of leaving a puddle after a few weeks of sitting. I replaced the speedometer drive parts which cut the leaking down but there is still a puddle. Because of the leaking I check the fluid level frequently, following the check it hot procedure. I've tried to get the local transmission shop to look at it and he said he will but it has been months. I remind him and he says he will but I get the feeling that he won't because parts for the th400 are hard to get. I live in a small town so there isn't a choice in shops. I tried the next town over and the shop there said it would be a few months until he had a chance to look at it. I don't trust it enough to go to far with it. I have rebuilt engines but never attempted an automatic.
Le Mans Master
Joined: Nov 2016
Posts: 9,297
Likes: 951
From: Lake Tahoe, CA
My 74 has a problem with either the torque converter or the transmission, I don't know which. After startup the car will back up about 10 feet then act like I put in the clutch, after 2 seconds it will start moving again. It will occasionally wait a few seconds to move at stop lights as well. It also leaks to the point of leaving a puddle after a few weeks of sitting. I replaced the speedometer drive parts which cut the leaking down but there is still a puddle. Because of the leaking I check the fluid level frequently, following the check it hot procedure. I've tried to get the local transmission shop to look at it and he said he will but it has been months. I remind him and he says he will but I get the feeling that he won't because parts for the th400 are hard to get. I live in a small town so there isn't a choice in shops. I tried the next town over and the shop there said it would be a few months until he had a chance to look at it. I don't trust it enough to go to far with it. I have rebuilt engines but never attempted an automatic.
https://documents.holley.com/112002.pdf
Btw, TH400 parts are available.https://www.monstertransmission.com/...ts_c_5254.html
Tech Contributor
Joined: Aug 1999
Posts: 14,385
Likes: 6,414
From: At my Bar drinking and wrenching in Lafayette Colorado
Nonsense. Without the special tools required to disassemble and re-assemble a TH400, he doesn't stand a chance. You can't even do the first step of removing the front pump without the front pump puller, and you can't compress and disassemble the clutch packs without a drum compression tool.
It's not your converter. You have a tranny problem. Usual cause is that the clutch pack drum seals are old, brittle, and leaking, so your clutches are burned. The TH400 is a common transmission, and any competent tranny shop has the parts and can fix one easily. All major auto parts stores can get TH400 parts (and every major mail-order place can get the complete rebuild kit, like Summit and Jeg's). However, if you can't fix it yourself, and if you don't have the tools to do it, you have to either pull the tranny out and get it to a shop, or you need to flatbed your car to a shop that can fix it. There are tranny shops in Greensboro, so start making calls and arrange for your car transport. Welcome to the joys of owning a half-century old antique automobile!
Lars
Lars
Last edited by lars; Aug 20, 2022 at 12:42 AM.
Thread Starter
8th Gear
Joined: Aug 2018
Posts: 8
Likes: 3
From: Mount Airy, NC
I was afraid it might be a trans rebuild not just a torque converter replacement. Rebuild kits are hard to find. After the local guy said that I got on line and checked. Many of the big places like Summit have them in their catalog but if you dig deeper you will find that they don't actually have them in stock and don't know when they can get them. I get C3 parts from Zip Corvette since they are in Virginia so parts generally show up next day. I called to see about a rebuild kit and the guy said they have been on back order for more than two years.
That said, I think I would replace the trans with a rebuilt one. Any recommendations for a source? Also what details will I need to order with, like tail length for instance?
That said, I think I would replace the trans with a rebuilt one. Any recommendations for a source? Also what details will I need to order with, like tail length for instance?
Thread Starter
8th Gear
Joined: Aug 2018
Posts: 8
Likes: 3
From: Mount Airy, NC
Ok, I've been looking into sources for rebuilt transmissions. I found a shop that deals in Monster Transmissions that is just 30 miles from here. I thought I'd get the trans and do the swap myself, but first I'd check them out online. Wow, eleven hundred complaints on BBB. Some were real horror stories.
So how about Jasper? I found an article comparing Jasper to Monster. Jasper was better but just barely. There are others out there but they are performance rebuilds. The mildest ones still promise firmer shifts. This is my wife's car and she will not appreciate firmer shifts. So again, any recommendations for rebuilt units?
So how about Jasper? I found an article comparing Jasper to Monster. Jasper was better but just barely. There are others out there but they are performance rebuilds. The mildest ones still promise firmer shifts. This is my wife's car and she will not appreciate firmer shifts. So again, any recommendations for rebuilt units?
