Checking Bellhousing Alignment

[Ron Earp]

I've been advised by my engine man that I should definitely check my bellhousing alignment before installing my transmission. I'm performing this on my BBF and Toploader, but I imagine the same should/could be done for some GT40 transaxles if a separate bellhousing is used. Anyone have any tips or advice on doing it?

I'm using a Lakewood bellhousing/scatter shield and have already sent it down to Jerico for truing of the two faces of the bellhousing. They were a little bit off.

Now I'm wanting to check to see if the bellhousing is aligned with the crank centerline. The plan is to mount the flywheel with a couple of bolts and then install the bellhousing. After that I use my dial indicator with a magnetic base on the flywheel and set the tip of the dial indicator on the inside rim of the bellhousing. Crank the engine over and record the run out on the dial indicator. Clearly the indicator needs to be securely mounted and the inside rim of the bellhousing needs to be smooth so as to not throw off the measurements.

Any other hints? Maximum run out acceptable, < 0.010"? That run out figure seems to depend a whole lot on who you talk to.

 

[Rick Muck- Mark IV]

Ron,

Look on the Ford Racing site, they have a "how to" for bellhousing install/centering/checking. Lakewoods are known to be a "little off". Quicktimes seem to be closer from the factory, but all should be checked.

 

[JohnC]

Ron, here's an alignment procedure from Lakewood.

 

[Pat Buckley]

I would also use more than a "a couple of bolts"......

To be safe I did it with the flywheel torqued in place.

Remember to divide the reading by 2 to get your actual runout......I went for less than six thousandths total....

 

[Seymour Snerd]

FWIW I just did this on my FE without the flywheel: I just put the magnetic base on the crankshaft flange.

I also bought a roller tip for the dial gauge (McMaster 20625A665, $22.26).

My bell housing had been powder coated, so I had to account for a couple thousandths of variation in coating thickness. But since I found three points about 120 degrees apart that were the same measurement, I was able to get away without adjustment.

 

[Ron Earp]

Hmmm, you fellows do this with the "midplate" mounted. Not sure what you call it, but it is the plate that goes behind the flywheel and mounts between the block and the bellhousing. If I try it that way not much of the alignment dowel sticks out, and what does stick out is the beveled part that won't align the bellhousing.

Which begs the question, my alignment dowels are too short or I'm not supposed to use that "midplate" at all?

R

 

[Pat Buckley]

I use the plate -

The dowels really shouldn't have much of a bevel - they should fit into the bellhousing fairly snugly.

 

[Ron Earp]

They fit snug and engage well without the plate. They fit snug with it, but not quite as well. Checking the runout now but my biggest problem is getting the magnetic base to hold well and the indicator positioned. Ally flywheel so I can't stick it where I'd like to put it.

 

[Pat Buckley]

I use an aluminum flywheel also - I stuck the dial indicator on the flywheel bolts......

Having an extra set of hands when you turn the engine is helpful as you've no doubt figured.

What I did is turn the engine 90 degrees, take a picture, turn it another 90, take a picture, etc.....(my memory sucks)

 

[Ron Earp]

Having a computer in the garage is a good thing!

Thanks fellows. From best I can tell I've got about 0.055" of total run out, sort of at the upper limit of what the adjustable dowel pins can do. I want to test with another set of hands in place though so that I can watch the indicator while the engine is being turned. And I want to check the mounting and so on, but it appears that it'll need adjustment.

Surfing around on the web it seems that very few get away without needing the offset dowel pins to sort this out. And those that don't check it seem to always invariably come around to doing it right due to problems with shifting or worse yet broken parts.

R

 

[Pat Buckley]

You will want to look at these dowels:

Impala Parts | ADJUSTABLE OFFSET DOWEL PINS .014" | Classic Industries

I used somethiing similar - they make life a lot easier.

 

[Eric A.]

I have seen jigs available to redrill the dowel holes in the block and bellhousing and then install bushings to fit the original dowel pin size or use oversize dowels. I just cannot remember where. It did require positioning the jig precisely on the engine and bellhousing so I couldn't see how it would be much faster or easier than using the offset dowels. The only advantage I could see is that you could prepare several bellhousings for one engine if necessary

 

[Brian Kissel]

Here is a link to a previous discussion about the alignment process. It also includes information about the BHJ fixture to relocate the dowels. I use a lot of BHJ fixtures and the quality of the stuff is great.
http://www.gt40s.com/forum/gt40-tech-powertrain-transaxles/26702-bellhousing-alignment.html

Brian

 

[Randy]

The CAV bellhousing was WAY WAY off, over 55 thou. I made high-off-set dowell to correct.I got it down to 5 thou. When I first measured the dail was spinning around so fast a thought I was doing something wrong.
I thought I got a bad unit,so I got CAV to send me another and it is the same!If you get a jig let me know I'll have you re drill this one!
Bottom line always check!
Randy

 

[Ron Earp]

How did you guys get the dowels out of the block?

About the only thing I'm coming up with is to center drill them, tap'em, and then slide hammer them out. I tried the vise grips and that was a no go.

 

[Jac Mac]

Just punch em from front to rear with pin punch, IIRC they are not blind holes. I dont take em out, just mod the bell as per attached dwg..

 

[Ron Earp]

They are blind as far as I can tell. I shall look again, but I'm pretty sure they don't have any rear access.

That is a good idea!

So drill out the bellhousing to 0.750". Then make a sleeve that is 0.750" ID and drill a 0.5" hole in the sleeve, but, drill the hole offset, then I can turn the sleeve and move the bellhousing around.

 

[Jac Mac]

They are blind as far as I can tell. I shall look again, but I'm pretty sure they don't have any rear access.

That is a good idea!

So drill out the bellhousing to 0.750". Then make a sleeve that is 0.750" ID and drill a 0.5" hole in the sleeve, but, drill the hole offset, then I can turn the sleeve and move the bellhousing around.

Not quite.. the 'stepped' washer ( ferrule) on RHS of dwg should be around 7/8 to 1"" dia, the 'step' about 5/8" dia & the 1/2" dowel hole are all concentric. The 5/8" loose fit in the bell/housing 3/4" hole should allow for the existing runout while you get it all concentric & once welded in the ferrules become a permanent part of the bell housing, due to the shape of the bell housing it might be necessary to trim the ferrule O.D. slightly to get it to sit square on dowel prior to welding...

 

[Ron Earp]

Not quite.. the 'stepped' washer ( ferrule) on RHS of dwg should be around 7/8 to 1"" dia, the 'step' about 5/8" dia & the 1/2" dowel hole are all concentric. The 5/8" loose fit in the bell/housing 3/4" hole should allow for the existing runout while you get it all concentric & once welded in the ferrules become a permanent part of the bell housing, due to the shape of the bell housing it might be necessary to trim the ferrule O.D. slightly to get it to sit square on dowel prior to welding...

Ok, that works too and is maybe a bit easier than what I understood. I shall try it. The tricky part will be, no, it won't, duh. I'll weld the damn thing while it is all on the block and lined up.

I am pretty sure I have some steel rod with a .500" ID hole and inch OD. It'd be possible to turn these off on the lathe.

 

[Jac Mac]

Ok, that works too and is maybe a bit easier than what I understood. I shall try it. The tricky part will be, no, it won't, duh. I'll weld the damn thing while it is all on the block and lined up.

I am pretty sure I have some steel rod with a .500" ID hole and inch OD. It'd be possible to turn these off on the lathe.

Looks like you are starting to read my mind, a lot of folk would like to be able to do that, even me!!!, update on dwg to ( I hope ) clarify..