tranny problem th350

[71chevylongbed]

i was driving my truck and when it went to shift to 3rd it started slipping like it was in neutral and would start bogging down and when i gave it some throttle it would start shifting back and forth between 2nd and 3rd, and 3rd would slip like crazy. when i give it enough gas to kick the tranny down it goes into 1st and then shifts to 3rd really hard skipping 2nd. and when i give it alot of gas it wont shift at all. it also is making a rattling sound and i would assumethat is a bad sign. apparently 500 ft lbs of torque and constantly driving it like i stole it was too much for it, 2nd trans this year tranny is only 3 months old with about 4,000 miles last trans lasted for a year with this motor

sorry for long post

[jmanz69]

Yeah, 500ft/lbs with a TH-350 = Kaboom! Did you have the trans built for that much power? They can handle it if you have good parts put in. Otherwise I would go to a TH-400. The 350's aren't meant for that much abuse. You will keep replacing them if you don't switch. Good luck.

[71chevylongbed]

yeah i told the guy at the trans shop how much power it had and that i wanted to be able to hot rod the crap out of it and pull my horse trailer with it and he said "oh yeah it can handle it no problem" i guess that shows you how much he knows. i should have put in a manual

[jmanz69]

I wouldn't be pulling a horse trailer with a TH-350 period. They are fine for 1/2 ton trucks and pulling medium wieght trailers. You should definately go with a TH-400 or a 4L80E. The 4 speed would be way expensive though. Should be able to get a good 400 core and rebuild at a resonable price.

[imdarren]

I would not waste any more time with the TH 350. Go with a TH 400, and have it built to the hilt. You will never need another tranny.

[71chevylongbed]

Originally Posted by jmanz69

I wouldn't be pulling a horse trailer with a TH-350 period.

yeah and i probably shouldnt floor it from every stop when i am pulling it. tranny has an 18 month 18,000 mile warranty so i will see how many more i can fry in that time period

[3 on the tree]

This is probably a dumb question, but have you upgraded the cooling system for the tranny? I can remember when there were alot of Chevy trucks out there pulling everything with 350/350 combos. I was one of them. Had a 70 burb with 406/350 towed race cars with it, stock trailers etc. Never had a problem with stock tranny. It had a big aftermarket cooler plumbed in line with the radiator cooler. I beat on this thing till the body fell off, finally pulled the motor and put it in a blazer,along with the trans.

[71chevylongbed]

Originally Posted by 71chevylongbed

yeah i told the guy at the trans shop how much power it had and that i wanted to be able to hot rod the crap out of it and pull my horse trailer with it and he said "oh yeah it can handle it no problem" i guess that shows you how much he knows. i should have put in a manual

ok so i take it down to the trans shop today and the guy asks me "have you been hot rodding it or racing stop light to stop light?" while he is asking me this i am thinking to myself does it really matter? and then he says that 500 ft lbs of torque may have done it in. read quote. and if that is the case then it is not covered by the warranty. then he goes on to tell me that the transmissions that they build for the drag race cars do not come with warrantys because hotrodding transmissions can cause them to fail at any time. they always seem to change their story when something breaks. all i know is that he said it could handle racing and towing and it came with the 18,000, 18 month warranty and if he wont honor that im going to be mad

[spencra]

Kick a$$ and take names my man.

If he can change his story than so can you. "Ah, no sir, i'm not hot-rodding my truck. No way, no how." F***'em if they can't take a joke.

Make them prove it.

[71chevylongbed]

[QUOTE=spencra] "Ah, no sir, i'm not hot-rodding my truck. No way, no how."

Make them prove it.[/QUOTE

thats what i told him when he asked me. the he said that if i had he would be able to tell when he takes it apart and then if he tries to get me to pay for it im gonna tell him he can shove it up his a$$ and keep it!!!!

[c-1072]

What do you guys think of my cheap tow hooks pretty flashy huh , i figured chrome is nice and for eight bucks how could i go wrong . :p

[spencra]

Originally Posted by c-1072

What do you guys think of my cheap tow hooks pretty flashy huh , i figured chrome is nice and for eight bucks how could i go wrong . :p

Woh, that post came out of left field.

[spencra]

Yeah, I would say go with the th400 for hauling stuff. It's meant for hauling and being abused.

THM350 - Medium duty 3 speed trans used from 1969 to 1989, Used in Buick, Olds, Pontiac and Chevrolet cars and Chevy & GMC light trucks until 1987. Generally used in straight and V6 and small block engines. Generally able to handle up to 400 foot pounds of torque

THM400 - The THM400 was GM's Heavy-duty 3 speed transmission used from 1964 to 1990. Used on large displacement, high torque engines and engines with towing packages. Generally found in Chevy & GM trucks, cadilacs and large displacement engined, full size GM rear wheel drive cars.

[Sweet72]

Cableguy0 has gone through a few in his truck too. A TH350 should be able to handle a hot street 350 for everyday driving. Now if you race and use nitrous or forced induction and are really twisting the hell out of it, of course it won't last for long. I find it hard to believe you're getting 500 ft. lbs. out of that motor.

[71chevylongbed]

Originally Posted by Sweet72

I find it hard to believe you're getting 500 ft. lbs. out of that motor.

i had it on a chassis dyno and it put out 226 hp and 456 ft lbs torque. so figuring for power lost through the driveline that should be about 300 hp and 500 ft lbs torque at the flywheel right?

[Sweet72]

That's one torquey engine you have there. Man, I was hoping for that kind of torque out of the 383 I'm building, now I may be disappointed if I don't achieve those numbers or better.

[Robert1970C20rstbukt]

Did you try manually shifting it?

[71chevylongbed]

yeah i tried manually shifting it and it will go into gear but when i give it gas it starts slipping. i took it for a quick drive yesterday and that rattling/grinding noise is worse than before so im guessing that i tore something up pretty good any ideas on what that noise might be?

[67ChevyRedneck]

Instead of getting another tranny, get your money back and invest in a 4L60 out of a new chevy truck. With a bowtie TV cable kit and a lock up kit you'll have OD. ALSO, the 700R4 and 4L60 have lower 1st and 2nd gear ratios than the turbo 350....not sure about the 400 though...The lower take-off gears will help with your hauling....also, do you have a 3.08 rear or a 3.73....a 3.08 may have contributed to your tranny frying. I personally think a 3.08 is too high for towing, even with a 350 tranny.