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Trans alignment

Wes Harden

Wes Harden

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Most of us are aware of timing chain adjustments after a block has been align honed, and indexing for the manual trans.
Is there a need to do automatic trans? How would one check?
 
The Automatic indexes on the engine block dowel pins, and the torque converter registers in the crankshaft pilot. Missing dowel pins, worn trans case dowel holes, worn torque converter pilot or crankshaft pilot hole can all create pump and torque converter damage/failure.
 
Copy that. What happens when the crank is higher in block( closer to cam) after block is align honed. It only .005 .007 can the front pump bushing handed and survive that? Balance issues?
 
That is a good question Wes, there is some wiggle room but not very much. Acceptable runout between the converter pilot and drive hub surface is about 10-13 thousandsth, we try and keep them under 5 thousandths, but I have seen over 20 thousandths even on factory stuff, so your .005-.007 should be in tolerance.
 
Always thought align boring kept everything centered... didn't realize it moved the centers.

I need to center my bell housing when I do my nv4500 swap.
 
Big Ray said:
Always thought align boring kept everything centered... didn't realize it moved the centers.

I need to center my bell housing when I do my nv4500 swap.
Click to expand...
Same here. They mill the main cap Mounting surface down so many thousandths, then rehone the bore on center. It shouldn’t change I thought.
 
Fastereddie said:
Same here. They mill the main cap Mounting surface down so many thousandths, then rehone the bore on center. It shouldn’t change I thought.
Click to expand...
That's what I thought too. With the use of bearings that are thicker to deal with the undersized crank journals it still should be on the same centerline as before.

I have heard of offset machining of the rod bearing journals to slightly increase stroke but not the main bearings.
 
It moves, if done right it will be @ .005. the 1st time. They have timing chains to compensate for align boring.
If it has been done more than once, who knows how much the center lines have moved.
Gen 1 blocks aren't getting any younger. Something to keep in mind.
I never considered flex plate index till recently, have checked it and adjusted a few manual trans.
1 was a 392 Hemi way back in the day, stuffed in a 31 chopped A.
 
a set of dowel pins offset ground. The bolt holes would probably have plenty of space, but could be reamed if needed.
 
just saw this again and all i can think is, "waiiiiiiiiiit a minute..."


wouldn't/shouldn't the crank go back into exactly the same alignment after align boring and grinding/polishing and ordering oversized bearings??? as far as timing is concerned, im having a hard time wrapping my head around this. why would my manual trans care what the thickness of the main bearing is???
 
Ok so when a block is align bored through the mains.
The caps are milled @ .005", bolted back on then a boring bar cuts both the block and caps, to round in spec main bearing diameter.
Under size bearing shells only compensate for a ground under size crank bearing surface.
 
soooo if they make bearings for oversized rods and undersized crank rod journals... you're saying they don't make crank bearings oversized? how/why could that be?:eek1::eek1::eek1::eek1::eek1:
 
theoretically, if doing what's drawn on the left in red... the timing is not going to off... the whole timing system would need to be changed??? timing gear size, tooth profile, and/or size of the links in the timing chain and space between the pins... in theory, have you not just thrown off the entire motor design by relocating the crank?? (unless you have adjustable cam gear and a tensioner, in which case shut up.)

Or, no??
 
Simply put, no.

Line boring resizes the main bearing bore on the crank centerline. The oversized bearings then allow the crank to remain in the intended centerline it was built with.

If it didn’t then yes you would have to deal with timing chain/cam to crank dimensional changes as well as the line up of the torque converter or clutch.

It’s been done thousands of times. The math has been worked out.

The key point is the new oversized hole for the crank main bearing is still on the same centerline just bigger. So with a thicker bearing to “fill the gap” of what was removed the crank is still where it was to start with.
 
Thicker bearing shells would indeed keep the crank in it's original position. I haven't looked for a larger od main bearing.
I do know they offer timing sets that compensate for align boring.
 
So I have looked at summit and Clevite, I can't find any bearings that are larger od. Only bearing to compensate for ground journals.
 
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