Hot Rod Forum banner

82 chevy longbox with fresh t-350 and a vibration

3K views 7 replies 6 participants last post by  speed_demon666 
#1 ·
i just installed a new th350 with stage 2 transgo, a 2000 stall b&m and a new flexplate in my 82 chevy longbox. before the swap i had minimal vibration, but now if i take my truck over 2000 in any gear i get a really bad vibration. new rear tires and 3 month old ujoints by the way. could i have a defective flexplate or sumthin?
any help appreciated
 
#3 ·
speed_demon666 said:
i just installed a new th350 with stage 2 transgo, a 2000 stall b&m and a new flexplate in my 82 chevy longbox. before the swap i had minimal vibration, but now if i take my truck over 2000 in any gear i get a really bad vibration. new rear tires and 3 month old ujoints by the way. could i have a defective flexplate or sumthin?
any help appreciated

Need to isolate the vibration.

Does it vibrate only driving / moving?

Will it vibrate with trans in park , vehicle stopped? IF so , is it possible for you to unbolt the torque converter...... slide it back into the trans so the engine can run with out the converter connected?

This would isolate the vibration to the flex plate IF it vibrates. If there is no vibration with converter loose..... then the converter may be the problem.

:cool:
 
#4 ·
it vibrates in 1 2 d and n i havent tried in park and i try not to get my revs that high in reverse. i was kinda leaning away from driveshaft because it says in my haynes book that if the vibration occurs at the same speed in all ranges (in my case right around 2000 rpm's) it will not be the driveshaft because in 1 2 or d it will be spinning at different rpms. i just really wanna get this fixed and dont want ***** to start blowin up on me or to hurt the new tranny.
 
#5 ·
over 2000 in any gear
Sounds like it can't be the driveshaft. First guess is converter or flexplate. Run it in park, up to 2000.

Wrong flexplate? If it had a 400 SBC flexplate on a 350 SBC, I would think the vibration would be so bad that you would shake the truck apart.

On some occasions, I have been able to add washers on the flexplate bolts to "balance" a minor vibration. IT is a pain because you need to add a washer, then test, then if it's worse, mark that bolt and move the washer to the next bolt..etc. I ended up with 2 wahers on one bolt on one car I did. It was a "rebuilt" converter that was out of balance.
 
#6 ·
speed_demon666 said:
i just installed a new th350 with stage 2 transgo, a 2000 stall b&m and a new flexplate in my 82 chevy longbox. before the swap i had minimal vibration, but now if i take my truck over 2000 in any gear i get a really bad vibration. new rear tires and 3 month old ujoints by the way. could i have a defective flexplate or sumthin?
any help appreciated
Check the pinion angle on your rear axle. It should be about 3 degrees (downward) relative to your driveshaft angle. Under load (acceleration), the rear axle housing will tend to rotate upward a few degrees and align with the driveshaft. If this is out of whack, you'll experience a vibration.

Antny
 
#7 ·
speed_demon666 said:
it vibrates in 1 2 d and n i havent tried in park and i try not to get my revs that high in reverse. i was kinda leaning away from driveshaft because it says in my haynes book that if the vibration occurs at the same speed in all ranges (in my case right around 2000 rpm's) it will not be the driveshaft because in 1 2 or d it will be spinning at different rpms. i just really wanna get this fixed and dont want ***** to start blowin up on me or to hurt the new tranny.
From this, it says the problem is on the engine.......or something spinning the same as the engine (flexplate, converter, front pump)........You also said in your 1st post, that you had minimal vibration before. What does that mean?....You had vibration before?

Was the tranny done at a shop?.......new trans, new flexplate?
 
#8 ·
it vibrated before just on the highway because i had unbalanced tires, the tranny is newly proffesionally rebuilt with a stage 2 transgo kit, i installed a b&m torkmaster 2000 converter and a new flexplate. i was looking at the old flexplate yesterday and it had 3 extra holes drilled not quite all the way through it and my new one does not have this was the old one balanced specifically to my rotating assembly.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top