Figures from dialing in bellhousing runout

DanEC · #1 (**permalink**) 06-09-2012, 12:00 PM

I think these figures are going to be OK but see what you think? I'm running a Toploader, Quicktime and bronze pilot bushing. This was the second run. After the first run I loosened the bellhousing and tapped it in the direction it was closest to centerline and then re-torqued the bolts again and re-measured. It appears this shifted it about a thousand.

Top .0128

Left .0155

Bottom .014

Right .0115

The fourth diget was just an interpretation when the needle fell between marks. Six thousands was what I remember from long ago as barely acceptable and I'm well within that.

Dan

FWB · #2 (**permalink**) 06-09-2012, 02:26 PM

while i have no idea what is acceptable or not...even though i have slept at several holiday-inns over the years...

but 6 thousandths is .006 your measurements are about twice that....

Gaz64 · #3 (**permalink**) 06-09-2012, 03:26 PM

Dan,

Your measurements are vague, measured in respect to what?

The point of alignment is the input shaft HAS to be in line with the crankshaft.

Your numbers are twice of .006, and .006 is too much off centre in my book.

Your bellhousing and/or block doesn't have dowels?

strictlypersonl · #4 (**permalink**) 06-09-2012, 03:40 PM

If those are numbers read directly from the dial indicator, your runout is about 0.002" left-to-right. That's a very good number, not requiring offset dowels.

charles roybal · #5 (**permalink**) 06-09-2012, 04:23 PM

Automotive Tech Articles | Lakewood Bellhousing Alignment Procedure

DanEC · #6 (**permalink**) 06-09-2012, 04:46 PM

Quote:

Originally Posted by strictlypersonl

If those are numbers read directly from the dial indicator, your runout is about 0.002" left-to-right. That's a very good number, not requiring offset dowels.

Yes that's correct. I didn't try to zero the dial indicator. I just set it to read and then took readings at 90 deg intervals by turning the crank. Top to bottom absolute figure was .0012. Left to right was out .0040. Runoout would be half of that figure or .002 in and .0006 in (.001 rounded for all practical purposes).

After posting I realized I had not put in the adaptor ring in the bellhousing that the Toploader requires. I re-ran the figures with the adaptor ring in and they didn't change much althogh the ring was very slightly elliptical I found out by spinning it around in the opening and reading the stationary dial indicator.

Keith Craft was to dial everything in but I'm not too sure they didn't forget so I thought I better double check it.

DanEC · #7 (**permalink**) 06-09-2012, 04:49 PM

Quote:

Originally Posted by Gaz64

Dan,

Your measurements are vague, measured in respect to what?

The point of alignment is the input shaft HAS to be in line with the crankshaft.

Your numbers are twice of .006, and .006 is too much off centre in my book.

Your bellhousing and/or block doesn't have dowels?

Keith Craft built motor - yes it has dowels. Measured with a magnetic base set on the crank flange and 1 inch dial indicator reading at 90 deg intervals around the bellousing register for the transmission. Numbers have to be divided in half for runout so they are well under .006.

Gaz64 · #8 (**permalink**) 06-10-2012, 02:48 AM

Dan,

I see how you do it, you are well under max spec.

RICK LAKE · #9 (**permalink**) 06-10-2012, 03:37 AM

DanEC Dan the spec you are looking for is .000" Have not ever seen this. If you can get down to .003" you are good. This is top to bottom and side to side. 2 of the numbers need to be negitive. The easy way is to buy the offset dowel pins and have them install and setup the bell this way. I did it the harder way with grinding out the holes, centering the bell and welding nuts on the locators for repeat assembly and bell being centered. It took 2.5 hours to get this correct. My lakewood was .038" out. I am down to .002"-.004", close enough for me.
Best thing to do is install flywheel, setup magnetic base and dial gauge and retest your measurments then come back with the numbers and we can see what off set dowels you need to get this setup into spec. 2 numbers plus and 2 numbers neg. You know which way to move bell. Once this is done, torque bell to block and get dowels install and twist to match holes. If you have the room, drilll and tap holes for bolts or allen head screws to lock the dowel in location. You are good to go after this. Rick L.

jon@harrison.ne · #10 (**permalink**) 06-10-2012, 11:01 AM

The measurements being discussed here do not address the angle between the the crankshaft centerline and the transmission centerline. In other words, they assume that the plane of the bell housing is orthogonal ( i.e. perpendicular ) to the crankshaft axis. This is probably a good assumption for a bell housing with machined mounting surfaces ( housing to block and housing to trans). This is not the case with some of the stamped bell housing / scatter shields that I have seen. I took mine to a machine shop and had the trans end milled parallel to the block surface. When I watched the operation it was obvious that they weren't parallel to begin with.