engine to bellhousing runout spec 904?

[65TerrorCuda]

Howdy, anybody know the bellhousing to crankshaft runout spec for a 904 off hand? Checked this due to some pump bushing wear and wondering if what I got is good to go. Didn't find squat on a search, maybe I'm using the wrong words.

Thank you,

 

[1WildRT]

Only spec I have is in an old Atra manual, it shows .008 as max.... Don't know if you are aware of it, but to check the runout the transmission case has to be empty.....

 

[65TerrorCuda]

Only spec I have is in an old Atra manual, it shows .008 as max.... Don't know if you are aware of it, but to check the runout the transmission case has to be empty.....

Yeah, I just got through doing it. The gutting was the easy part, trans is out for a refresh. It was .007 or .008 total due to being a little hard to see the numbers. Phone video'd while I rotated her over.

Still don't understand why you're supposed to use a .007 dowel to correct a .014 offset. Makes no sense to me.

Here's what I just followed,
https://www.moderndriveline.com/mm5/graphics/00000001/bellhousing_align_procedure.pdf

Thanks for the quick response Wild!

 

[matthon]

Still don't understand why you're supposed to use a .007 dowel to correct a .014 offset.

To measure, mount indicator and spin 360 degrees.
Mark the largest # on the bell, then zero out the indicator on the opposite side, 180 degrees.

Spin again and record the largest number.

This is done because it's difficult, if not impossible, to set the dial indicator on the exact centerline of the crank.

Mine had a .020 maximim total indicator reading, aka offset, with 0 on the opposite side.

Moving it .020 will just make it .020 off on the opposite side.

I used .014 dowels, moving it .014 for a total offset of .006.

Mine must not exceed .008 maximum total indicator reading. That's any radius along the circumference.

So, if my max is now .006 with 0 on the opposite side, the max number from the center is actually half of that, .003.

And yes, I measured again, and the max is now .006.
Half of .006 is .003, which is damn good, imo.

 

[65TerrorCuda]

To measure, mount indicator and spin 360 degrees.
Mark the largest # on the bell, then zero out the indicator on the opposite side, 180 degrees.

Spin again and record the largest number.

This is done because it's difficult, if not impossible, to set the dial indicator on the exact centerline of the crank.

Mine had a .020 maximim total indicator reading, aka offset, with 0 on the opposite side.

Moving it .020 will just make it .020 off on the opposite side.

I used .014 dowels, moving it .014 for a total offset of .006.

Mine must not exceed .008 maximum total indicator reading. That's any radius along the circumference.

So, if my max is now .006 with 0 on the opposite side, the max number from the center is actually half of that, .003.

And yes, I measured again, and the max is now .006.
Half of .006 is .003, which is damn good, imo.

I had to make a diagram with the measurements to get my head around it but finally did. Thing is, with the available offset dowels it'd make my .004 into .003, probably not worth it.
Good work on your part! This wasn't the most fun thing to do.

 

[1WildRT]

Put a new bushing in the pump, use the proper tool to align the front pump halves when assembling the pump, if the halves aren't properly aligned the bushing will fail & the seal will leak...

 

[65TerrorCuda]

Put a new bushing in the pump, use the proper tool to align the front pump halves when assembling the pump, if the halves aren't properly aligned the bushing will fail & the seal will leak...

Yessir, I did all the bushings except the tiny one inside the stator support. That one looks like new. Not sure what tool you speak of, I just flipped the pump upside down and reinstalled in the case to align it while torquing the bolts.

I saw somebody used a huge hose clamp to align the halves. Wonder if you could set the converter on the bench and lower the loosely bolted pump/gutted case onto it and torque the bolts from inside.

I might never finish this trans lol

 

[1WildRT]

Yessir, I did all the bushings except the tiny one inside the stator support. That one looks like new. Not sure what tool you speak of, I just flipped the pump upside down and reinstalled in the case to align it while torquing the bolts.

I saw somebody used a huge hose clamp to align the halves. Wonder if you could set the converter on the bench and lower the loosely bolted pump/gutted case onto it and torque the bolts from inside.

I might never finish this trans lol

I've always done the convertor & a band clamp... Using the convertor assures the bushing & stator support are aligned while the band clamp aligns the housing halves..

 

[65TerrorCuda]

I've always done the convertor & a band clamp... Using the convertor assures the bushing & stator support are aligned while the band clamp aligns the housing halves..

Now I've got a plan, thanks brother! Gotta bug Hughes again to get my converter back from refresh. Getting closer

 

[oldkimmer]

A lot of ppl put too much thought into bellhousing run out. Never thinking of the flex plate and converter run out. Or flywheel/ clutch runout. Just tightening the converter to the flex plate can pull it outa whack so the converter rubs on the pump bushing. Lots that ppl never think about. Kim

 

[65TerrorCuda]

A lot of ppl put too much thought into bellhousing run out. Never thinking of the flex plate and converter run out. Or flywheel/ clutch runout. Just tightening the converter to the flex plate can pull it outa whack so the converter rubs on the pump bushing. Lots that ppl never think about. Kim

It didn't have a front seal leak, but the pump bushing was scuffed halfway around, enough to catch a fingernail. Oddly the tc didn't have any visible wear. Hadn't considered looking at the flexplate other than for cracks.

I was guessing that the bushing was probably worn due to gravity and the heavy converter and geartrain resting on it during cold starts, plus my valve body doesn't charge the converter in park.