Technical SBC Bellhousing Alignment? Or?

OK. So, I'll ask my question and then explain.
Is there any way to get even a decent estimate of the bellhousing alignment with the clutch in place?

Now I'll explain. FYI, car is a '56 Chevy 150, 383, ST10, old Lakewood*****tershield and block plate. When I put my hot rod together originally, I can't remember for sure if I checked the bell/crank alignment. It went together fine and worked well initially. The transmission had some miles when I got it, but looked good inside(even when I had it rebuilt recently I was told that, with a few exceptions, it looked good inside). It eventually started getting hard to do the 1-2 shift at high rpm and one of the synchros was going. FYI After I had the transmission rebuilt I read that much of my trouble may have been synthetic oil. Anyway, when it was rebuilt, the shop used a new forged front bearing retainer and there was much less play in the input shaft than these transmissions traditionally have. I reinstalled the transmission(went together pretty easy) and only ran the car for about 1 minute when it started screeching. I shut it down and pulled the transmission. It appears that the input shaft and the front bearing retainer rubbed enough to get blue. The transmission guy took it back and opened it up. It was just the input and the bearing retainer that had any issues. The only guess we have come up with is that the bell is out of alignment just enough for the difference in the input shaft play to be the issue. But, we would like to check it before disassembly to have a greater****urance if this was the problem or not. Hence the original question.

Thanks for any help.

 

Anything is possible,
That Lakewood *****ter shield stamped steel?
It could be tweaked from a previous incident.

 

Stamped steel Lakewood*****tershields are notoriously out of alignment, and all the makers of steel bellhousings state they need to be checked and adjusted for alignment. I do it on every one I've ever installed, and some have been so far out of alignment that the offset pins with the largest .011" offset barely got things within the .005" maximum misalignment allowed.
Afraid you're going to have to pull the pressure plate, and set up a dial indicator on the flywheel to check and adjust alignment. Even if you could somehow check alignment with the pressure plate in place, there's no way to install and set the offset pins without pulling the bellhousing anyway.

 

Yes, it is stamped steel.

 

If it didn't happen until after the rebuild, I would suspect defective replacement part's, namely the bearing retainer.

 

We had to use these alignment dowel pins on*****ter shields.

offset dowels come in a few different offsets.
We used these to center the bell housing to the crank center line.

 

That's why I was hoping there was a way to get even a ballpark measurement before I disassembled it any further. So that we could hopefully say either "yes, alignment was definitely the issue" or "no, that shouldn't have created such a problem". I'm going to take it apart and check it either way. It would just be nice to know if there were any other factors that created the problem.

 

That would be pretty tough to do without a solid mounting point for the dial indicator. Clutch removal is almost a must-do.

 

Is it hard to remove the clutch? You will need to have the bellhousing loose more than likely anyway to adjust the alignment.

 

You could try setting up a dial indicator on the fingers a the pressure plate and see what you get. Then use the Moroso dowel pins like Anthony suggested and tac weld them to the can. This way if you have to pull the clutch again you can skip that step.

 

I'am looking at the same problem and don't want to remove clutch and pressure plate. What I'am going to try to do is put one of my clutch alignment tool and put in my lath and drill a hole in the center and put in the indicator mounting shaft in and mount the indicator off of that to see how far my bell housing is out of spec. and go from there. If it is out by a lot then I will have to take it all apart.

 

how will you keep the wobble out of it?

 

I tried to do this. But I couldn't get things to stay where I needed them surprisingly(or maybe unsurprisingly).

 

I was going to try this also since I have a couple extra input shafts. But, there was too much movement in it to accurately measure the tolerances I need for this.

 

We would drill the side of the block and insert roll pins into the dowels.
This locked them into the block.

 

I recently helped someone with an OT LS with a T56 transmission alignment check. The T56 came with a checking plate and we followed their instructions all the way. We had a good indicator set up and everything was well within spec. Things like a total TIR of .005" were less than .002".

I have checked a few Chevy installations using factory parts and they were good to go as is. So with aftermarket*****tershields, it is a must to do your homework once and get it right. My local speed shop had the offset pins on the last one we did. I recall we had to draw a few sketches so it made sense.

 

I can't think of any fixture that you could try with the clutch in place that would be accurate and repeatable at the tolerance you need. So the clutch needs to come out. Then hopefully you have enough room with the engine in the car to get the housing aligned if needed.

 

Can you PM
Me info on this? I’m putting a T56 in my daughters car, I’m really curious how you indicated it.

 

Disregard the request. Googling was my friend!

 

Checking alignment off the center shaft will likely give a false reading since the center pilot shafts will have slop in them, and not be true. If you're going to do this important step, don't cut corners, and end up with a bad reading, and possibly all the work done for naught. If it shows you need an alignment it's going to possibly be incorrect by cutting corners. So just bite the bullet and do it the right way, so the work isn't done wrong.
And please don't weld offset pins into the bellhousing! The fit of those pins into the block is snug, so welding them into the bellhousing will only result in fighting to get the bellhousing mounted if they're welded in.

 

The pins ain’t snug if you take a little bit of Emory cloth to them. They ain’t that tight to start with.

 

Even if you could get an indicator attached somewhere on the clutch, the clutch itself may not be perfectly concentric. So you would be starting with some eccentric reading most likely.
The only way to do it correctly is the old reliable clutch removal and indicator attached to the flywheel. When you try to take shortcuts, it usually results in more work or bad results in the end.

Edit Note: After thinking about this some more, I realized that I mis-stated.......nope, I realized I was WRONG. Even if the clutch was not perfectly centered, if an indicator was stuck on it with a magnet, it would still turn a concentric circle. It would amount to the same thing as attaching the magnet to the flywheel at that same location.

The only way it would be eccentric would be if the indicator was mounted in the center of the clutch fingers with a bushing. Then it would turn either concentric or eccentric depending on how well the clutch itself was centered to the flywheel/crank.

Sorry for the mistake.....

Still though, the best way is to remove the clutch to indicate the housing.

 

I've had alignment probs wayy back in the early 70s when I tried to dial in a few Lakewoods while in the cars.
When I thought everything went great, I still suspected the bellhousing was off a bit by the way the*******s acted after several hundred miles... like things were not perfect. Inspections after a few hundred miles appeared to have the wear patterns in the pilot bushings look not quite right, ..
I took the Lakewoods to a machine shop to have them precision checked on a surface plate. Surprise- the deep drawn pressed*****tershields measured perfectly level, perfectly parallels, ... Congratulations to Lakewook for being spot-on.
So from then on, I made it a point to always dial them in with the engine nose-down to eliminate any chance of slight dial-indicator-droop by gravity influence.
I slap a magnetic base on the flywheel, and then dial it in by rotating the crank with the pointer running along the bearing bore.
Since I always seemed to get a slightly different reading when the bellhousing bolts were tight vs loose (maybe I'm a little too picky?) , I started taking my readings with bolts snug, then loosen them to tap tap to a different reading, tighten, then take a reading.
That seemed to make everything perfect to get many miles out if a street hotrod. for me.
Engine nose-down is the only way I'll do it today.
I dono if Ive helped or not.

 

For initial check,as long as the indicator had a solid grip on the clutch and the clutch itself doesnt move, the indicator will still rotate centered on crank.
Another thing you can do is onced dial in is to drill for a couple of small roll pins. Then you can re install and it will stay lined up.
Dont forget to check the face as well.

 

Where would you be drilling for roll pins? I ask because I’m wondering what needs to be done after a bell housing or*****ter shield is dialed in to be put back like it was.

 

We just followed the instruction book. The T56 and everything came from American Powertrain. I still have the manual around, I took a copy home for "homework". I will dig it out if you have any questions. The kit came with a sub-plate that we used first IIRC, it was a 2-part indication task, IIRC. This was a year ago.

 

I would pick a spot down low. Maybe just above lower bolts in block.
3/16 pins should be good. Make sure to use a soft pin just in case you have to drill them out later.
Only need to drill 1/2 deep or so.
I guess you really shouldnt have to if the offset dowels stay where you put them.
But nothing wrong with having a little insurance.

 

No worries, I looked on Google and found a maker of the plate and a video of them doing it.
Plate is 89$ so seems money well spent.

 

I see, you mean for the bell housing. I don’t think that’s needed if one uses offset dowels. I don’t think you can move a BH much with the dowels in place.

 

Yeah, there is no way around it. The 1st one my buddy got was way too tight to go on the back of the engine, he sent back the OG one and the new one went on smooth as silk.