Broken 350 th Trans

psychomotors

Dragway Regular
Mar 31, 2011
896
0
0
Bonne Terre, Mo
My buddy has a 85 SS monte and he has broken 3 cases at the bell housing. He is using a Poly trans mount and solid engine mounts. He has a pretty strong 406 in it . I am leaning towards the engine causing the damage but would like some other opinions.
 

SSedan64

Dragway Regular
Oct 5, 2009
948
0
0
MACON, GA.
Rear axle movement is most likely causing the damage. A Driveshaft with too little clearance with the Yoke and Tran's Output Shaft can cause this.
Have the rear Control Arm bushings been changed?
 

psychomotors

Dragway Regular
Thread starter
Mar 31, 2011
896
0
0
Bonne Terre, Mo
I'm not sure because alot of work was done to it before he got it,roll cage,etc. I am starting to think that its engine related because it shakes like crazy at idle but as you increase the RPMs, it starts shaking really bad. He said that he ordered a balanced rotating assembly and I'm thinking that maybe they internally balanced it by mistake. He is using an external aftermarket balancer and flexplate. He is gone on a trip for the weekend and when he gets back, he is going to call the company and check with them as to what they sold him.
 

TNTS79

Dragway Regular
Jan 6, 2006
1,252
0
0
Illiniois
If it shakes that bad the motor won't last long! If it's already broke 3 bellhousings im surprised it hasn't beat the main caps out of that block yet!!
 

SSedan64

Dragway Regular
Oct 5, 2009
948
0
0
MACON, GA.
That doesn't sound good.
Shops don't normally Internal balance SBC400s unless instructed to or the Crank is designed to be Internally balanced. Usually when it's Externally balanced the Flexplate will come with the Crank unless they didn't have to add/remove weight from it..
 

psychomotors

Dragway Regular
Thread starter
Mar 31, 2011
896
0
0
Bonne Terre, Mo
Yeah, I hear you. I will just have to wait till he gets back from his trip so he can call and find out. He has $3000 wrapped up in this thing and is so disgusted with it that he says he will sell me the entire engine( carb to pan) for $1500. I told him that we would try to figure out the problem first.
 

psychomotors

Dragway Regular
Thread starter
Mar 31, 2011
896
0
0
Bonne Terre, Mo
I talked to him last night and he has called them at Competition Products . They told him that anytime someone requests an engine to be balanced, they automatically internally balance it. He was only really wanting the parts match weighted and not internally balanced. I asked about seeing any Mallory in the crank and he said the only thing he remembered was lightening holes. He showed me the parts in the catalog he ordered i.e. externally balanced 400 crank. I told him that it would have been easier for the shop guy to switch cranks to an internal and balance than to try to balance the external (cheaper also) So now he is going to switch the flywheel and balancer to internal balanced and hopes it takes the shake out.
 

SSedan64

Dragway Regular
Oct 5, 2009
948
0
0
MACON, GA.
It would've been nice if they had told him that or put it on the Balance card. :!:
Hopefully there wont be any Bearing damage.
That's the 1st time I've heard a Shop say that about balancing a 400. :-k
As you said, much cheaper to start with the correct parts.
 

psychomotors

Dragway Regular
Thread starter
Mar 31, 2011
896
0
0
Bonne Terre, Mo
I'm just repeating what the salesman told him,I dunno. I agree with you that they should have said something on paper. I am really hoping that this will cure the problem and that his bearings are still okay. I say "I" because he is disgusted with the whole ordeal and has lost interest in it. If this fixes it, he might get back into enjoying it. If not, I will probably end up buying it and I really cant afford it but he has to many top quality parts in it for me not to. Geez,lol.
 

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