Thread: B&M shift kit disaster... HELP

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Hey guys, new here but I knew this was the place to get great advice. 1982 Chevy Impala, 350v8 , th350 tranny, originally took tranny down to change flexplate and torque converter. Did that successfully. Had a leaky trans line so I replaced them with PVC hose and fittings to my intercooler, installed b&m shift improver kit, followed all directions to the "T" , installed new filter & gasket, and a new adjustable vacuum modulator , put everything back together. Happy!! Put in 5 QTS of valvoline max life atf , shifted thru all gears slowly while foot on brake, put it in drive and it took off slowly, shifting fine,made it almost around the block before it stopped moving, hit gas harder and it caught back on and took off, turned to pull back in to my garage and hit the gas and I heard a POP and seen something shoot out the back went to go see what it was and it was the accumulator cover, spring and snap ring. I'm sure it was locked on there how did it pop off? I got a new o ring reinstalled it and now the car won't move at all in any gear

Welcome to CHR! I'm definitely not a tranny expert, but the first thing that hit me was the 5 quarts of Valvoline Max Life ATF. If you changed out the torque converter you'd have needed a lot more than five quarts to fill your system, IMO. It sounds to me like you ran the system low on fluid, rev'd it up as it got a suction prime and then put a massive pressure surge through the tranny. I'd say that you've got a tranny rebuild in your future, but then again I led this with a disclaimer that I'm not a tranny guy.... Hope I'm wrong.

First, welcome aboard. It's good to see you here.
It's been maybe 20 years since I had a TH350 open.. but, there's at least 2 manual that can provide you with the test procedures to help you diagnose your problem.

And of course there's always youtube, I haven't done any searches there but I'd bet dollars to donuts you'll find something there.

I can't say I've ever seen or heard of that cover "popping" off. Which kit did you install? Changing shift points only or shift points and pressures? B&M kits are very reliable, usually they install with no issues..

Hope it helps and let us know what you figure out.

Thanks nice to meet you all, I used the B&M kit, changed the valve body plate and upper and lower gaskets, the 2 separator hold downs with my stock one on top (filed it flat) via instructions, left one check ball in, removed the other 3. perfectly aligned everything, torqued bolts to spec. Made sure everything was good internal clearance wise. Sealed her up. Now later after the cover blew off, I removed the spring, sealed it back up with snap ring, and thought the same thing about the low fluid, added 2 more quarts and it started moving again, but won't up shift without almost flooring it, checked detent cable it was correctly adjusted. I've heard of these kits putting so much pressure on the internals that you have to reach over 2500 rpm just to get it to upshift to second. I'm just mad I did all that hard work and have to take it right back out, think I'll just buy one brand new, don't add a shift kit and call it a day. The basic tci sizzler 350 tranny is around $1100 , almost every trans shop in Indy charges $1200-2000 for a rebuild... Might as well go brand new. Thanks for all the help

I tend to agree with the others that your initial problem was likely not having enough fluid in the transmission. My experience is you normally lose a minimum of 4 quarts of fluid just dropping the pan on a TH350. A dry convertor will normally require anywhere between 2-5 more quarts and a drained cooler and lines could hold up to an additional 1 quart.

Now some more bad news for you. You probably smoked the clutches and/or bands and some of that material likely migrated into the convertor and is sitting in the transmission cooler and cooler lines. The cooler and lines are not a big deal....they can be blown out. Besides getting a bunch of crap in the convertor, running the car extremely low on fluid possibly also damaged the internals of the convertor. Yeah, I'm saying to be on the safe side you will also need to replace the convertor again........or you can take a chance and possibly have to do everything over for a THIRD TIME. That is why new/rebuilt transmissions require a new or rebuilt convertor in order for the warranty to be honored.......and believe me what you now is a used convertor.

Here is the procedure I normally use to initially fill a new transmission/ torque convertor.

Before installing the convertor into the transmission slowly put a minimum of 1-2 quarts of fluid in it. Once the transmission if installed and everything hooked up add 4 quarts of fluid to the transmission. Start the engine (on slow idle) and immediately start adding fluid checking the level often......helpful hint if there is no fluid showing on the bottom of the dipstick a full quart at a time can be added. Check the dipstick after each quart. Once the fluid level reaches the tip of the dip stick add fluid a 1/2 quart (pint) at a time. Once the fluid is between the add and full line, get in the car put your foot on the brake and run the transmission thru the gears, put it back in park and recheck the level. I usually stop adding fluid when the dipstick shows it is about 1/2 a pint low (between the full and add marks). To properly check the fluid level the transmission needs to be a full operating temperature and that is not going to happen idling in the garage. Check for leaks then take the car out and drive it easily for a couple of miles, go back to the shop and recheck the fluid level.....add fluid if necessary.

Here is a link to a fluid capacity chart.

https://www.tciauto.com/tc/fluid-capacity/

THIS IS JUST A GUIDE!!! Due to differences between stock and aftermarket transmission pans, coolers and cooler lines and convertors the only real way to check the fluid level is with the dipstick.



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Originally Posted by Mike P

I tend to agree with the others the other that your initial problem was likely not having enough fluid in the transmission initially. My experience is you normally lose a minimum of 4 quarts of fluid just dropping the pan on a TH350. A dry convertor will normally require anywhere between 2-5 more quarts and a drained cooler and lines could hold up to an additional 1 quart.

Now some more bad news for you. You probably smoked the clutches and/or bands and some of that material likely migrated into the convertor and is sitting in the transmission cooler and cooler lines. The cooler and lines are not a big deal....they can be blown out. Besides getting a bunch of crap in the convertor, running the car extremely low on fluid possibly also damaged the internals of the convertor. Yeah, I'm saying to be on the safe side you will also need to replace the convertor again........or you can take a chance and possibly have to do everything over for a THIRD TIME. That is why new/rebuilt transmissions require a new or rebuilt convertor in order for the warranty to be honored.......and believe me what you now have now is a used convertor.

Here is the procedure I normally use to initially fill a new transmission/ torque convertor.

Before installing the convertor into the transmission slowly put a minimum of 1-2 quarts of fluid in it. Once the transmission if installed and everything hooked up add 4 quarts of fluid to the transmission. Start the engine (on slow idle) and immediately start adding fluid checking the level often......helpful hint if there is no fluid showing on the bottom of the dipstick a full quart at a time can be added. Check the dipstick after each quart. Once the fluid level reaches dip stick add fluid a 1/2 quart (pint) at a time. Once the fluid is between the add and full line, get in the car put your foot on the brake and run the transmission thru the gears, put it back in park and recheck the level. I usually stop adding fluid when the dipstick shows it is about 1/2 a pint low (between the full and add marks). To properly check the fluid level the transmission needs to be a full operating temperature and that is not going to happen idling in the garage. Check for leaks then take the car out and drive it easily for a couple of miles, go back to the shop and recheck the fluid level.....add fluid if necessary.

Here is a link to a fluid capacity chart.

https://www.tciauto.com/tc/fluid-capacity/

THIS IS JUST A GUIDE!!! Due to differences between stock and aftermarket transmission pans, coolers and cooler lines and convertors the only real way to check the fluid level is with the dipstick.

Excellent advice, Mike! Especially the shout out at the end about it the capacity chart being a GUIDE. Some OEM coolers internal to the radiator hold a lot more than a quart if additional fluid, from what I remember.

Thanks for all your help. Lesson learned. The only way to learn is by trial and error. And this was a big one on my end, I guess I grew impatient and was ready to get back out there. I'll use all your info on my next one! Thanks again, if anything changes I'll report back to tell you my findings.