Bellhousing indexing

[jrvariel48]

I was speaking to a gent at a car show this week and he brought up bellhousing indexing. I'd never heard of this so I searched it on line and it seems very interesting. I didn't do this to my motor when I installed the T5 trans and I'm wondering if this is one of the reasons I went through a pilot bearing rather quickly. Is this something I should be paying attention to? I'll be installing a fresh motor this fall so that would be the time to do it. It's an 8BA motor bolted up to a T5 with a bellhousing adapter from Speedway with the Ford stamped steel adapter in between. Thanks Joe

[JSeery]

The bellhousing transmission mounting surface needs to be parallel to the flywheel surface and the indexing hole for the transmission needs to be on the centerline of the crankshaft. One would assume these conditions were met during fabrication, but like most anything the only way to be sure is to check them. The Ford manuals I have provide the procedure and even provides a diagram on how to fabricate checking aids.

[19Fordy]

Very interesting. Makes sense to have perfect alignment, if possible.
http://www.moderndriveline.com/Techn...t-indexing.htm

[Ronnieroadster]

Any time I install an after market bell housing to the back of the Flathead I always check the centerline location. Most times I discover the bell housing is way off the centerline to correct the problem i machine offset dowl pins to relocate the bell housing as needed. Most bell housings i find are square to the flywheel surface.
Ronnieroadster

[Pete]

Usually not necessary but I machine the back of the block square to the mainline. (requires a BIG lathe)
I have had 4 over the years that were off over .010.

For the center hole, which is almost never dead on, after removing the original dowels, I dial the housing in and install taper pin dowels.

All of this may seem nit-picky but misalignment of parts creates friction. Friction is power loss which could mean finishing second instead of first.

Here is a pic of the mainline bar used to chuck the block in a lathe to machine the back.

[Mart]

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Blimey Pete I can see why you wrote BIG in capital letters. That lathe must be a monster.

[Pete]

Originally Posted by Mart

Blimey Pete I can see why you wrote BIG in capital letters. That lathe must be a monster.

It was a 36 inch Axelson. I don't have access to it any more.
The next block will be done in a CNC. Much easier.

I saw a fairly big lathe when I was in Seattle,Wa. once. It would swing a little over 5 ft and had a 30 ft. bed. It had a carriage you could ride on.

[supereal]

Originally Posted by Pete

It was a 36 inch Axelson. I don't have access to it any more.
The next block will be done in a CNC. Much easier.

I saw a fairly big lathe when I was in Seattle,Wa. once. It would swing a little over 5 ft and had a 30 ft. bed. It had a carriage you could ride on.

We were offered a lathe that came from a battleship as surplus. It was a real monster. We passed, as we already have a big long bed lathe the we use for driveshafts, rear axle housing, etc. , but it was certainly impressive to see that seagoing machine!

[19Fordy]

Pete,
Please post a photo of that lathe, if possible.

[Pete]

Originally Posted by 19Fordy

Pete,
Please post a photo of that lathe, if possible.

I didn't own a camera back then. (50's)

There are pics of big lathes all over the internet.

[cas3]

i would love to have a giant lathe to play with. but, like most folks i dont have room for one in the shop. i see them go for cheap, even scrap prices quite often because no average guy can move one, haul one, or store one

[jrvariel48]

Originally Posted by Ronnieroadster

Any time I install an after market bell housing to the back of the Flathead I always check the centerline location. Most times I discover the bell housing is way off the centerline to correct the problem i machine offset dowl pins to relocate the bell housing as needed. Most bell housings i find are square to the flywheel surface.
Ronnieroadster

Ronnie, is there dowels on the back of the 8BA block? I'm not familiar with that and I don't have one to look at. Thanks, Joe

[Ronnieroadster]

Originally Posted by jrvariel48

Ronnie, is there dowels on the back of the 8BA block? I'm not familiar with that and I don't have one to look at. Thanks, Joe

Yes Joe theres removable dowels on the 8BA. Unfortunately no aftermarket offset dowel pins are made that match how Ford made their pins. When I make the pins for the 50A or the 8BA I offset my three jaw Buck chuck in the lath and carefully make a pair of offset pins. Not a simple task but worth the effort. Also like Pete wrote using tapered pins is another option if you have the pins and the tapered reamer. On occasion i have just relocated dowel pins to another spot doing it this way I use straight pins with no steps I do this to center line the automatic bell housings on my race car.
Ronnieroadster

[jrvariel48]

Ronnie, Is it possible to drill out the dowel hole on the flathead to match a size that's more common? This company makes three different sizes.
Thank you, Joe

http://www.robbmcperformance.com/products/dowels.html

[Kurt in NJ]

I reality the bell housing doesn't matter, what matters is that the transmission centerline matches the crankshaft centerline

[JSeery]

Originally Posted by Kurt in NJ

I reality the bell housing doesn't matter, what matters is that the transmission centerline matches the crankshaft centerline

Would depend on how the transmission mounts to the bellhousing. If the transmission has a lip that indexes into the bellhousing, then the bellhousing is controlling the centerline and needs to be correct.

[jrvariel48]

From what I've seen and understand, this is crucial to the T5 because there is no end play at the input shaft and it doesn't tolerate side play very well because of the tapered bearing. This is what I gathered from watching videos and doing a lot of reading. I have no experience with this. I don't believe the trans mounting to the bellhousing can be changed, so the difference, if there is one, is made up by clocking the bellhousing to center the input shaft into the crank. It looks like a simple thing to check and fix. My trans must be out of tolerance, which is .005,because in the last 4000 miles I went through a pilot bushing and an input shaft bearing. The closest offset dowels available are .496 and the 8BA dowel I pulled out is .404. I wanted to know if the dowel holes in the block could be drilled out to match the .496 available dowel

[xelhan]

RobbMc seems to make good stuff. Why not encourage them to make dowels for the Flathead V8

[xelhan]

JSeery wrote: The Ford manuals I have provide the procedure and even provides a diagram on how to fabricate checking aids.

Are you able to post that procedure?

[donald1950]

back in the late 60 my engine builder used a dial indicator on attached to the flywheel with the adapter on the motor and an empty transmission case input shaft hole to center and zero the transmission, any correction needed he made by slightly enlarging the bolt holes and then re-drilling and using oversize dowel pins to lock the transmission case in place.
when i put a T-5 in my '41 pick up i had 3 adapters in place, a chevy to early ford, a hogs head to the early ford adapter, and then a Dwight Bond hogs head to T-5 adaptor. and i was fortunate when i dial indicated with all 3 in palace and i came in at .001. ran good & never ate pilot bushings...
on the hard top race car, at Vallejo Speedway in Northern Calif, with a 301 chevy, that process worked well also as our driver had a hook to lock the gearshift lever in place and hold it in 3rd gear. one time he ran a 50 lap race and when he pulled into the pits he discovered he did not hook the shift lever down and the transmission did not pop out of gear during the race.....