broken th350 bellhousing

[sgblazer2]

i have a 89 chevy s10 blazer with a 383 sbc and a th350. i have broken the bell housing on the trans three times. i've secured the motor and trans, they are not moving, the trans yoke has 1 inch of clearance, stiff drag shocks, a 4.56 rear gear,a mini spool and drag tires. if any one can help, thanks.

[Tod74]

you secured the motor and trans? as in solid mounts? I would run a rubber mount on the trans.

[Racefab57]

Run a poly trans mount.David.

[sgblazer2]

the motor mounts are solid and the trans is a new stock rubber mount.

[Racefab57]

I repeat- solid mounts, or motor plates; POLY TYPE TRANS MOUNT! David.

[jmarksdragster]

Rubber mount is fine, you have to allow for chassis flex. Look at your pinion angle, make sure you have no more than 4 degrees. Are you using traction bars? What kind? When I had my chevelle I used plumbers strap to keep the rubber mount intact if it broke.

[sgblazer2]

no traction bars and the pinion angle may be off, i put a 2/2 inch drop.

[jmarksdragster]

That will do it. Correct pinion angle and run traction bars the limit housing rotation.

[sgblazer2]

thanks jmarks, how exactly did you use plumbers strap?

[jmarksdragster]

I ran a 1/4" bolt front to back through the metal part of the mount, and ran the strap under between the mount and crossmember. It would limit the mount from pulling apart, but still allow the mount to absorb the flex.

[SST4530]

Well I don't think it should be cracking the bell housing in the first place. I've been racing for 25 years and never busted a trans case. You've got a real problem if you are. Do you have sub frame connectors or a roll cage? Sounds to me like you have way to much chassiss flex along with not enough flexibility in the mounts.

If go to an ultra bell you may still brake something just in a different location, so your just covering up the problem and transfering it to the next weakest link. Just my $.02

With soild mounts and rear rubber mount, you must be getting alot of chassiss twist to bust the case. have afew questions:

1. How much converter are you running?
2. Transbrake?
3. Slicks?

I think you need a cage, front strut tubes and cross bar to stiffen this thing up. Just my $.02 :wink:

[sgblazer2]

the stall is a 2000, iknow its needs more with the 292/292 duration cam, no trans brake and 28/12.5-15 mt et street.

[lanham]

I used to have a long wheelbase s-10 that i put a 350 engine in.It was a street truck.Before i got the problems out of it i busted two bellhousings on it.Before it busted the bellhousings it had a bad vibration in it.The only things that i found was the tip of the bellhousing was touching the firewall and the starter was tight against the frame(very little clearance) and was a stock size starter.I clearanced both areas and i had been running a one piece driveshaft,(it destroyed both of those too) and after the clearancing i went back with the stock two piece driveshaft.After that i had no more vibration and no more problems.I had stock motor mounts and tranny mount.Just giving you something else to look at.This truck ran 13.40s in the 1/4 so it wasn't no big high horsepower deal.

[sgblazer2]

thank lanham. my best time with all the problems was 9.146 in the 1/8

[bjuice]

you can best believe the tranny is moving "flexing" or it would not crack...the cheapest way i can tell you to fix this is a MID-PLATE..this is why they make these plates..to stop the tranny/motor from moving in that area.....a mid plate should stop the cracking.

Brian

[DaKoTaKiD]

bent driveshaft, or excessive runout.

[kiesel]

there are three huge clutches are lugged to the case on a th350. if you have it set up to shift hard this will cause the th350 to breack the case. This is the only transmission that uses that style clutch instead of a second gear band. It does have a second gear band but only for engine braking. hope this helps.

SnK Performance
REAL WORLD POWER

[qiksix]

i'm having the same problem but at the other end, the cone cracks. trans has been in same car for 8 years no changes, cracked 2 since being refreshed.

[sgblazer2]

I have put a 8pt. rollcage, traction bars, motor plate, and pinion angle shims on the blazer and the problem is fixed!! Iam no longer breaking the bellhousing and I picked up a half sec. Thanks for the help!

[jmarksdragster]

Good job!! It's surprising what tying the car together will do with ET and you'll find that consistancy will improve as well. 8) 8) 8)