Hot Rod Forum banner
1 - 13 of 13 Posts

·
Registered
Joined
·
332 Posts
Discussion Starter · #1 ·
I'm finding .010" TIR to be what most people recommend as a maximum run out for a bellhousing. I have the MDL adaptor plate to mount a T-5 to a stock Ford bellhousing on a 351W and I'm getting .012"TIR. This is a street application. Does being .002" over require installing offset dowel pins to try to get this under .010"?
 

·
More for Less Racer
Joined
·
20,218 Posts
Modern transmissions like the T-5 and T56 are rather intolerant of the input shaft being off alignment....I'd fix it is you have the time and capability, just as insurance against a future problem.

If you can't, you don't have much choice but to roll with it and hope it never acts up.
 

·
Registered
Joined
·
332 Posts
Discussion Starter · #5 ·
I believe you take the TIR divided by 2 which would be how much you need to move the bell to be in spec. So, mine would be .006" vs. a max of .005".
 

·
More for Less Racer
Joined
·
20,218 Posts
The .010" spec worked for older muscle stuff like Muncie's, Toploader's, Super T-10's, NP A883's that have ball bearing input shaft bearings that can handle some misalignment...but the modern stuff has tapered roller bearings and they can't handle misalignment.
They went to needle bearing input shaft bearings in the back of the crank instead of bronze bushings for the same reason.
 

·
Cars, Trucks, Boats, Motorcycl
Joined
·
7,481 Posts
I believe you take the TIR divided by 2 which would be how much you need to move the bell to be in spec. So, mine would be .006" vs. a max of .005".
Also need to note what DIRECTION it has to be moved... can't just jam some offset dowel pins in...
.
 

·
High Performance Rear Ends
Joined
·
3,764 Posts
Before you center the hole you need to make the face of the bell housing parallel to the back of the block. Then center the hole.
 

·
Registered
Joined
·
3,604 Posts
Buy a set of lakewood adjustable dowel pins. I am cheap. But these are worth every penny. You can easily get the bell within 5 within 10 minutes. They are also reusable on your next block.
 
1 - 13 of 13 Posts
Top