The Stovebolt Site Forums The Shop Area Engine Shop Clutch housing alignment

I have a 1941 pickup, model AK. It has a 235 mated to the original 216 clutch housing. I’ve checked the run-out of the pilot hole in the clutch housing and have found that it has to move .014” to bring into spec. Are adjustable alignment pins available and who sells them? If they’re not available, what can I do?

I would suggest elongating the bellhousing bolt holes in the proper direction to bring the bearing retainer hole into concentricity with the crankshaft centerline, then drilling the bellhousing and the back of the block for drive-in guide pins once the alignment is established properly. That should be a "one time" operation unless it's necessary to remove the bellhousing again for some reason.
Jerry

The service manual for 47-51 says that the dowels should be pulled from the engine, the bellhousing aligned and then the dowel holes drilled with a 13/32" drill and then reamed to 27/64" for oversize dowels. The bolt holes probably have enough play to allow aligning without the dowels in place. I would imagine the process is the same for the earlier (1941) trucks.

The 55.2 truck service manual says to ream the dowel holes to 21/32" so from those measurements, the 235 dowels are already larger than the 216. The runout spec for the clutch pilot hole is 0.008 inches in both manuals, so it only needs to move 0.006 to get within specification.

Rumor had it that some engines came from the factory with up to 0.040 misalignment. Others have said that you shouldn't swap belhousings between blocks. I have done lots of swapping without problem. Maybe I'm lucky.

I have heard that there were/are offset dowels for just this purpose but the manual quotations indicate that the tech writers were unaware of that if they really existed. One indication of misalignmet would be shortened clutch-gear bearing life in the transmission. I have not seen this problem though.

Misalignment would likely shorten the clutch gear bearing, but also would contribute to slipping out of top gear. I've seen that happen if the pilot bearing is too sloppy. It basically "walks" the clutch gear out of engagement with the shift sleeve.

I have read the same material in the manuals, but I understand it as being for the powerglide. Different housing altogether from the three speed housing. There’s no way to fit a drill, stubby drill bit, get the holes straight and still be able to drill through both the housing and block.I was thinking of making my own offset dowels, enlarging the housing holes in my mill and making a drill guide to enlarge the block dowel holes. Wish this would be as easy as the V-8’s!!! Does anyone have any other ideas?

Stand the block up on the base of a radial drill press, with the bellhousing bolted snug, but not tight to the back. Dial indicate the bellhousing hole concentric with the rear main bearing bore or the crankshaft flange and torque the bolts tight. Recheck alignment, and drill and ream for a few dowels- - - -1/4" or 5/16" should be plenty big. Drive a few dowels into the reamed holes and press on.
Jerry

Do a web search for offset dowel pins. There are places that will sell you the right ones based on your indicator measurements.

Good point, but there was no powerglide used in trucks before 55 for sure, so why would they put that info in the 47-51 Truck Service Manual?

Jerry, Good idea, but not everyone has a drill press big enough to stand a block up in it.

"press on" indeed. LOL!

I have a tall drill press, keeping around for just such purpose, but never use it, Bridgeport serves most all other purposes!

Ed

Here are a few pics of what I’m dealing with. The only access I have is from the inside. So, I can’t drill for new pins with the housing bolted to the block.

Yeah, that would be tight for drilling. I've borrowed a 3/8" right angle drill before to drill in a tight spot. Maybe with a stubby bit and right angle drill it would be do-able. Might be tough to keep aligned, though.

Is there some reason you can't remove the engine from the frame? The job you're contemplating isn't a weekend project. It would best be done with at least a partially disassembled engine- - - -a bare block with nothing but the crankshaft in it would be the best approach. I've got a couple of bare blocks and several bell housings out in the shop- - - - -in the next few days I'll look at the alignment dowels and figure out how the factory did it. Probably the best bet would be to make some offset dowels and clock them for the minimum runout.
Jerry

Look here - - would these help ? ?

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

jim

That's what I'm suggesting- - - -but they would probably have to be machined out of round stock to fit the stovebolt engne block and bell housing. I doubt that there's enough demand for them to make a supplier tool up and stock a supply of them.
Jerry

It can cause undue wear on your input shaft bearing. I have a Tremec TKO 600 on my 292. Warranty requires less than .005" runout. I used the offset pins with the set screw in the center that lock the dowel in place and make adjustment easy. I got it to .002" I think. The pins I bought were .007" offset. You order the size you need. https://www.summitracing.com/search...ord=Transmission%20offset%20dowel%20pins

The factory methods 70 years ago were "measure with a micrometer- - - -mark with chalk- - - -cut with an axe". Getting obsessive-compulsive about imaginary stuff is a luxury today's hobbyists can afford- - - -not so much on a production line. Some people lie awake at night wondering why the faucet on the kitchen sink isn't dripping! How much wear does an input bearing get while sitting on a shelf while the car builder spends 10 years getting the vehicle ready to make its first road trip?
LOL!
Jerry

I apologize for being late to the game here but the one question I have is are you trying to get the bellhousing in spec simply because its out of spec, or are you doing it because the trans does not want to slide in freely?

I ask this because its a lot of work to do what you are contemplating simply to get it within specification. One way to see if you actually have a problem is to make up some pins out of long bolts, and install on the bellhousing, then install the trans on the pins and see if it slides into the new pilot bushing with ease. If it does, I think you are going to be just fine. if it jams up, wont install because the center is so far off, then you might have to do the modifications or try another bellhousing.

It cost me $60 to not void the warranty on my $3500 transmission. I believe the question in the original post was if they were available and where to get them.

Not inexpensive but here are offset dowel pins. https://www.shiftsst.com/accessories-dial-in-kits-dowel-pins/p37
Make sure how much you need to move it to center because you should only need to move half the distance that it measures off.