I found you by way of the GM Square Body forum. I'm getting ready to do a rebuild for my '76 C10 and started the hunt for a good TH350 core. This video was perfectly timed! Great information!! Thanks!
Note - I mention posting a link to the pump checking tool as shown in the video at 11:35-12:00 however have not be able to locate it for sale on any reputable website. I bought it well over 5 years ago off eBay (no idea who the seller was). You can make one by simply taking a TH400 converter hub and welding a shaft to it of the same diameter or make your own, using a set of pump gears as a guide to make the lug cut-outs.
Thanks for this great video, and all your other fantastic instructional videos! Your knowledge of transmissions is truly amazing. I have a few 70's GM car projects, Chevys and Pontiacs, and I've collected some Chevy and BOP th350 cores for them over the years. I'm going to have to rebuild at least 2 of them, probably 3, so your rebuild vids will help tremendously. I'll have to buy you some coffee! 🙂I've tried rebuilding a th350 before, so have the tools and some experience, but it didn't shift right, so my first attempt failed. It turned out to be the new detent cable. Although it looked like the old cable in terms of length, and I adjusted it the usual way, I think the cable wasn't actuating the valve all the way. Not knowing what to do at the time, I took the th350 back apart looking for the reason. Finally, I decided to try that new cable in one of my running cars and removed the pan to watch the cable action with the detent valve and it wasn't pushing the valve all the way in with the carb at WOT. I didn't see any way to adjust it so it would work right. I put the original cable back on, and it operated the valve properly. So, now I know the new cable was the problem, and I also know from now on to make sure I verify the cable is properly operating the detent valve before buttoning up the pan. My question is what do you do when you need a new detent cable? This cable was listed as working for my 79 TA, but it didn't. It's the type with the long metal end with the long slot in it for the carb linkage. Also, I picked up a th350 from a 77 Ventura a couple weeks ago that I'd hoped I could just clean up, change the fluid and filter and run it. I felt good about it because the guy said it came from a running car, and it was complete, with torque converter, cooling lines, filler tube and dipstick. The fluid looked good on the stick. Once home, I cleaned it and dumped the fluid. Looks good cleaned up. But, there was a lot of sludge in the pan. It may still run with new fluid and filter, but the amount of sludge made me think those clutches must be too worn, so I'll have to go through it. Fortunately, it was just mud and not pieces or chunks. One other thing, I have another BOP th350 core I picked up a few years ago. The case looks a little different from my 77-79 BOP cases. Being BOP cases, they have that valley at the top of the bellhousing. The 79 case has a big C9 cast in the valley, and the 77 has a big C12. This different case instead has a huge B4H cast on the driver side of the bell housing. Nothing in the valley. This one looks like a much older version of the th350 compared to the others. It has the same pan, and generally everything else is the same, except for a couple of details. For example, the newer ones have a notch in the top rear part of the case for use with the upper bolt of a bench mount to help secure and stabilize the case when on the mount. This older case doesn't have the top notch made in the case. The 6" tail housing on the old case is not as beefy(less reinforcement) as the ones on the later cases. So, while I have the expert here, I thought I'd ask if you've noticed those differences before between the older and later th350's. Also any idea what those cast letters and numbers mean? Sorry for the long diatribe. But thanks for any thoughts you can share! Now, going back to watching your other vids 🙂, Steve
Hi Steve, thank you for the views and kind words...Re the detent cable, I always provide a new one or ensure the customer knows to check the detent cable for wear and replace it if it's a special/aftermarket set up. Re your BOP TH350, let me know if there's any casting codification on the 1-2 accumulator housing cover...If so, it's a 69-72 BOP unit and the year of production will be represented by the two large numbers towards the top of the cover...If there's nothing on the 1-2 accumulator housing cover but instead you find letters/numbers stamped into the governor cover housing, than it's a 73-81 unit...The year of production is represented by the last two numbers in the code if on the governor cover. LMK.
@@nickstransmissions Hi Nick, thanks for your quick reply! Yes, the new detent cable I used was an original replacement, made by Pioneer I believe. I like to keep things original, including using original Q-jets, so it all fits and works together like it should. I wanted to install a new detent cable, since I was making the tranny like new. Don't know why that new cable didn't work right. The old cable worked fine. Holding the old and new side by side, they seemed to be the same. There seems to be numerous variations. I'll have to find a different source for them and try again to find one that fits my 79 Trans Am properly. And thanks for the info about the date codes. I'll look for those numbers. It'll be interesting to know which years they are. I'll let you know what I find. Thanks again!
Enjoyed it...i knew most of these...checking for end play and @ 27:26 feed through binding are my two favorites to go to. Maybe bring along a lttile metal bolt or use your key to dip into the existing transmission fluid to smell for burnt fluid. Before I buy.. I'm really wanting to drop the pan..check filter, magnet and pan bottoms for debri. Got to get the seller on board that you'll properly re-install everything. If it's too clean, clean magents with new dry filter...then I'd be wary.
Thanks, Larson FamFarm. Yes, great tip bringing a pencil or telescoping magnet to drag/dredge the bottom of the pan through the dipstick tube hole. I am also wary of a very clean pan unless the seller shows me either paperwork or some other equivalent evidence the unit has just been gone through and never installed/ran (very rare are these available for core prices, which is what I'm paying).
Hey been loving these videos I have both th 350 and th409 transmissions questions for ya th350 occasionally no reverse wiggle shifter and it goes in and out but hold shifter in reverse works great and th400 spits fluid out dis tick tube trans works amazing just does it on a hill (overfilled)? Ok that’s your channel rocks and these videos are great wish you were local to me I would bring ya a th350
Thanks, madmechanix! Appreciate the kind words and views. Your reverse issue sounds like more of a column shifter or issue with the mechanical shift linkage going to the transmission as opposed to an internal transmission problem. The TH400 may be overfilled or under filled - they will vent fluid in both situations.
I have an '84 C20 all stock 350 auto transmission Rwd, I believe TH 400, I'm not positive, but recently it's begun to not drop into lower gear when approaching a steep grade and also dropping into a lower gear when passing. The truck was a one-owner California truck, but sat from 2001 until last year when I picked it up. It's got 113,000 miles on it and overall looks pretty straight, engine/body wise.It shifts well from a stand still, fluid is good, looks and smells good, just wondering if you've got some ideas. Great videos, just found your channel after posting in the square body forum. Thanks a lot!
Hi Gman100, thank you for watching...I'm thinking either kick down/detent solenoid is bad, detent or detent reg valve sticking in the bore in the valve body or vacuum modulator system not functioning...I'd first check vacuum at the modulator to ensure you have at least 15hg. If you do (and the hose isn't cracked or damaged in anyway), I'd test the modulator...You'll have to look up the test procedure but you can use a hand-held vacuum pump to test it. Once the modulator is off, take a pencil magnet and remove the modulator valve - see if it's stuck or dragging real bad...If so, take bench buddies (small abrasive hones) and polish the bore (bench buddies are used with a drill)...Also, if the valve has real bad scoring or feels rough to the touch, put it in the drill and polish each land with sand paper (800-1000 grit) - spray it and the bench buddies with WD40.
Yep, just re-watched...I actually cannot find a link to that tool anywhere which is why it's not in there...I'll pin a comment so folks are aware as it just looks as though I forgot to put the link. Thanks for the prompt.
I found you by way of the GM Square Body forum. I'm getting ready to do a rebuild for my '76 C10 and started the hunt for a good TH350 core. This video was perfectly timed! Great information!! Thanks!
Hey Ben - thank you! Glad you are rebuilding it yourself...
Post any questions here or on Squarebody and I'll respond as soon as I'm able to.
@@nickstransmissions I appreciate it! I've started down the rabbit hole of all your great videos!
Appreciate the views and support, Ben!
Note - I mention posting a link to the pump checking tool as shown in the video at 11:35-12:00 however have not be able to locate it for sale on any reputable website. I bought it well over 5 years ago off eBay (no idea who the seller was). You can make one by simply taking a TH400 converter hub and welding a shaft to it of the same diameter or make your own, using a set of pump gears as a guide to make the lug cut-outs.
Thanks for this great video, and all your other fantastic instructional videos! Your knowledge of transmissions is truly amazing. I have a few 70's GM car projects, Chevys and Pontiacs, and I've collected some Chevy and BOP th350 cores for them over the years. I'm going to have to rebuild at least 2 of them, probably 3, so your rebuild vids will help tremendously. I'll have to buy you some coffee! 🙂I've tried rebuilding a th350 before, so have the tools and some experience, but it didn't shift right, so my first attempt failed. It turned out to be the new detent cable. Although it looked like the old cable in terms of length, and I adjusted it the usual way, I think the cable wasn't actuating the valve all the way. Not knowing what to do at the time, I took the th350 back apart looking for the reason. Finally, I decided to try that new cable in one of my running cars and removed the pan to watch the cable action with the detent valve and it wasn't pushing the valve all the way in with the carb at WOT. I didn't see any way to adjust it so it would work right. I put the original cable back on, and it operated the valve properly. So, now I know the new cable was the problem, and I also know from now on to make sure I verify the cable is properly operating the detent valve before buttoning up the pan. My question is what do you do when you need a new detent cable? This cable was listed as working for my 79 TA, but it didn't. It's the type with the long metal end with the long slot in it for the carb linkage.
Also, I picked up a th350 from a 77 Ventura a couple weeks ago that I'd hoped I could just clean up, change the fluid and filter and run it. I felt good about it because the guy said it came from a running car, and it was complete, with torque converter, cooling lines, filler tube and dipstick. The fluid looked good on the stick. Once home, I cleaned it and dumped the fluid. Looks good cleaned up. But, there was a lot of sludge in the pan. It may still run with new fluid and filter, but the amount of sludge made me think those clutches must be too worn, so I'll have to go through it. Fortunately, it was just mud and not pieces or chunks.
One other thing, I have another BOP th350 core I picked up a few years ago. The case looks a little different from my 77-79 BOP cases. Being BOP cases, they have that valley at the top of the bellhousing. The 79 case has a big C9 cast in the valley, and the 77 has a big C12. This different case instead has a huge B4H cast on the driver side of the bell housing. Nothing in the valley. This one looks like a much older version of the th350 compared to the others. It has the same pan, and generally everything else is the same, except for a couple of details. For example, the newer ones have a notch in the top rear part of the case for use with the upper bolt of a bench mount to help secure and stabilize the case when on the mount. This older case doesn't have the top notch made in the case. The 6" tail housing on the old case is not as beefy(less reinforcement) as the ones on the later cases. So, while I have the expert here, I thought I'd ask if you've noticed those differences before between the older and later th350's. Also any idea what those cast letters and numbers mean?
Sorry for the long diatribe. But thanks for any thoughts you can share! Now, going back to watching your other vids 🙂, Steve
Hi Steve, thank you for the views and kind words...Re the detent cable, I always provide a new one or ensure the customer knows to check the detent cable for wear and replace it if it's a special/aftermarket set up.
Re your BOP TH350, let me know if there's any casting codification on the 1-2 accumulator housing cover...If so, it's a 69-72 BOP unit and the year of production will be represented by the two large numbers towards the top of the cover...If there's nothing on the 1-2 accumulator housing cover but instead you find letters/numbers stamped into the governor cover housing, than it's a 73-81 unit...The year of production is represented by the last two numbers in the code if on the governor cover.
LMK.
@@nickstransmissions Hi Nick, thanks for your quick reply! Yes, the new detent cable I used was an original replacement, made by Pioneer I believe. I like to keep things original, including using original Q-jets, so it all fits and works together like it should. I wanted to install a new detent cable, since I was making the tranny like new. Don't know why that new cable didn't work right. The old cable worked fine. Holding the old and new side by side, they seemed to be the same. There seems to be numerous variations. I'll have to find a different source for them and try again to find one that fits my 79 Trans Am properly. And thanks for the info about the date codes. I'll look for those numbers. It'll be interesting to know which years they are. I'll let you know what I find. Thanks again!
You're welcome...Yea, could be that you have a defective cable....Yea let me know on what you find out re that BOP TH400...
Enjoyed it...i knew most of these...checking for end play and @ 27:26 feed through binding are my two favorites to go to. Maybe bring along a lttile metal bolt or use your key to dip into the existing transmission fluid to smell for burnt fluid. Before I buy.. I'm really wanting to drop the pan..check filter, magnet and pan bottoms for debri. Got to get the seller on board that you'll properly re-install everything. If it's too clean, clean magents with new dry filter...then I'd be wary.
Thanks, Larson FamFarm. Yes, great tip bringing a pencil or telescoping magnet to drag/dredge the bottom of the pan through the dipstick tube hole. I am also wary of a very clean pan unless the seller shows me either paperwork or some other equivalent evidence the unit has just been gone through and never installed/ran (very rare are these available for core prices, which is what I'm paying).
Hey been loving these videos I have both th 350 and th409 transmissions questions for ya th350 occasionally no reverse wiggle shifter and it goes in and out but hold shifter in reverse works great and th400 spits fluid out dis tick tube trans works amazing just does it on a hill (overfilled)? Ok that’s your channel rocks and these videos are great wish you were local to me I would bring ya a th350
Thanks, madmechanix! Appreciate the kind words and views. Your reverse issue sounds like more of a column shifter or issue with the mechanical shift linkage going to the transmission as opposed to an internal transmission problem. The TH400 may be overfilled or under filled - they will vent fluid in both situations.
I have an '84 C20 all stock 350 auto transmission Rwd, I believe TH 400, I'm not positive, but recently it's begun to not drop into lower gear when approaching a steep grade and also dropping into a lower gear when passing. The truck was a one-owner California truck, but sat from 2001 until last year when I picked it up. It's got 113,000 miles on it and overall looks pretty straight, engine/body wise.It shifts well from a stand still, fluid is good, looks and smells good, just wondering if you've got some ideas. Great videos, just found your channel after posting in the square body forum. Thanks a lot!
Hi Gman100, thank you for watching...I'm thinking either kick down/detent solenoid is bad, detent or detent reg valve sticking in the bore in the valve body or vacuum modulator system not functioning...I'd first check vacuum at the modulator to ensure you have at least 15hg. If you do (and the hose isn't cracked or damaged in anyway), I'd test the modulator...You'll have to look up the test procedure but you can use a hand-held vacuum pump to test it. Once the modulator is off, take a pencil magnet and remove the modulator valve - see if it's stuck or dragging real bad...If so, take bench buddies (small abrasive hones) and polish the bore (bench buddies are used with a drill)...Also, if the valve has real bad scoring or feels rough to the touch, put it in the drill and polish each land with sand paper (800-1000 grit) - spray it and the bench buddies with WD40.
@@nickstransmissions wow, thanks so much for the info, big help!
What "link in the description"?
What specific information do you need? Ill reply with a link to that information and update the desc later
@@nickstransmissions At 12:10. 4L60E Pump tool.
Yep, just re-watched...I actually cannot find a link to that tool anywhere which is why it's not in there...I'll pin a comment so folks are aware as it just looks as though I forgot to put the link.
Thanks for the prompt.