bellhousing alignment, to offset or not?

[Blue Viking]

I have just checked the alignment on my Quicktime bell-housing. To the best of my ability, i have determined it to be out maximum 0.005 between the 11 and 5 o'clock positions, which is the maximum allowed (0.01 divided by two). While this is ok, the devil in me tells me to get two .007 offset dowels, which should put the max runout at .002 the opposite direction. I am thinking the error margin in the rather basic dial indicator "could" possibly put the offset over the limit. Should i bother with it, and am i thinking this correctly?

[NAZ]

There is always error in measuring so leaving it at the maximum allowable misalignment is not a comforting feeling. The misalignment spec is a trade-off between transmission performance and difficulty of achieving the spec.

As a machinist and an experienced engine builder, I'm in the camp that believes it's better to be as close as practical on nominal specs so this is exactly what I do. The offset dowels are cheap and easy to use -- why wouldn't you get the alignment as close as practical?

[mike223]

I am thinking the error margin in the rather basic dial indicator "could" possibly put the offset over the limit. Should i bother with it, and am i thinking this correctly?



There is definitely a margin of error if you don't have exactly the right equipment, and if you don't approach the whole process "perfectly".


My final check was this (requires clutch fork assembly, and also allows for setting the pivot ball height - bonus):


1- Check clutch fit on input shaft to determine how tightly the splines engage.

2- Complete the final assembly (engine, flywheel, clutch , pressure plate, clutch fork/throwout bearing, bellhousing, transmission) outside the car (preliminary fit check) - leave pilot bearing out for now.

3- Use clutch fork to release pressure plate and spin clutch (using transmission output shaft - transmission in gear) to center clutch perfectly on input shaft.

4- Release pressure plate to capture clutch - leave transmission in gear.

5- Rotate (rattle back + forth) output shaft to determine how much play the input shaft has in the clutch splines - very little, but it should not be bound up - it should feel + look just like it did in step #1 - you can observe it through the clutch fork hole in the bellhousing.

6- Leave clutch engaged, rotate engine crankshaft 90 degrees - recheck step #5.

7- Repeat step 6 (at least 2 more times - for 360 degree full rotation) until you're comfortable that the input shaft is not (at any point) bound up in the clutch due to misalignment.

8- If it needs offset dowels it will show up on at least one of the (4) 90 degree rotations.



Hope that makes sense,

Mike


P.S. - Don't forget to take it back apart and install the pilot bearing - the pilot bearing was left out to avoid piloting the input shaft to the center of the crankshaft and causing a misleading fit.

[Blue Viking]

There is always error in measuring so leaving it at the maximum allowable misalignment is not a comforting feeling. The misalignment spec is a trade-off between transmission performance and difficulty of achieving the spec.

As a machinist and an experienced engine builder, I'm in the camp that believes it's better to be as close as practical on nominal specs so this is exactly what I do. The offset dowels are cheap and easy to use -- why wouldn't you get the alignment as close as practical?

I'm thinking exactly like you. Just wanted to check if I was over thinking this too much. I will get the dowels, although I won't exactly call them cheap at $44 for the pair. These little things keep adding up...

[Blue Viking]

There is definitely a margin of error if you don't have exactly the right equipment, and if you don't approach the whole process "perfectly".


My final check was this (requires clutch fork assembly, and also allows for setting the pivot ball height - bonus):


1- Check clutch fit on input shaft to determine how tightly the splines engage.

2- Complete the final assembly (engine, flywheel, clutch , pressure plate, clutch fork/throwout bearing, bellhousing, transmission) outside the car (preliminary fit check) - leave pilot bearing out for now.

3- Use clutch fork to release pressure plate and spin clutch (using transmission output shaft - transmission in gear) to center clutch perfectly on input shaft.

4- Release pressure plate to capture clutch - leave transmission in gear.

5- Rotate (rattle back + forth) output shaft to determine how much play the input shaft has in the clutch splines - very little, but it should not be bound up - it should feel + look just like it did in step #1 - you can observe it through the clutch fork hole in the bellhousing.

6- Leave clutch engaged, rotate engine crankshaft 90 degrees - recheck step #5.

7- Repeat step 6 (at least 2 more times - for 360 degree full rotation) until you're comfortable that the input shaft is not (at any point) bound up in the clutch due to misalignment.

8- If it needs offset dowels it will show up on at least one of the (4) 90 degree rotations.



Hope that makes sense,

Mike


P.S. - Don't forget to take it back apart and install the pilot bearing - the pilot bearing was left out to avoid piloting the input shaft to the center of the crankshaft and causing a misleading fit.

Sounds like a good procedure to check for binding. The engine already has the pilotbearing installed, so i won't be able to perform it exactly like this, but I'll do a check anyway once everything is hooked up except the driveshaft. Using hydraulic release bearing, so have to wait until the engine and transmission is installed in the car.

[Sdonnel]

My initial build runout was at the .005” limit as well. Within a short time, I found an rpm related vibration while driving or in neutral with the clutch out (sitting still). Bought the offset dowel and got the runout down to .0005”. No more vibrations at any rpm since then. It’s cheap insurance. Do it and know it’s done right.

Scott

[Blue Viking]

My initial build runout was at the .005” limit as well. Within a short time, I found an rpm related vibration while driving or in neutral with the clutch out (sitting still). Bought the offset dowel and got the runout down to .0005”. No more vibrations at any rpm since then. It’s cheap insurance. Do it and know it’s done right.

Scott

Yep, already ordered and on the way across the pond along with a lot of other miscellaneous parts.

[NAZ]

You're doing it the correct way -- good luck with your build.

[SteveP]

I'm assembling my clutch and bellhousing now. I don't know how to check the alignment. I always thought you simply put the clutch plate on with the alignment tool and the bellhousing on the alignment dowels. If it fit, you were good to go. I know I'm missing something when you are talking about dimensions and the transmission instructions talk about measurements. U tube videos show measuring the runout of the flywheel as it rotates. That does not seem to be what you are measuring because it is done independently of the bellhousing. Please excuse my ignorance and any advice or a link to detailed instructions will be greatly appreciated.
Also, which driveline adapter do I need to attach a TKO 600 to the IRS pumpkin? You guys cost me a lot of money when I followed your advice and changed from a T-5 to the 600. When I started my engine on a test stand and heard the engine run, I was glad you talked me into the bigger transmission. The engine sounds like it will eat T-5's for lunch. I have the silver adapter and I'm not sure it's the correct one. Mike Forte already exchanged driveline yokes with me so I have the correct spine count.

[NAZ]

https://www.youtube.com/watch?v=vO9f4FhK13U

[SteveP]

https://www.youtube.com/watch?v=vO9f4FhK13U

Thank you. I am eager to visit you when I get back to Az. Maybe next month but for sure in November. Should I register my roadster in Az? Is it easy there? I can do it in Washington or Idaho if they are better to deal with.

[NAZ]

November is a great time to visit AZ and by then this Covid-19 thing should be in the rear view mirror. When I built my car and took it to the MVD (same as DMV in other states) to have it inspected and titled/registered I made an appointment (required) for the inspection and after the inspection waited in line for the title & registration. The whole process took around an hour as I recall and it wouldn't have been that long but the inspector was admiring the car and asking a lot of car-guy questions outside the typical inspection process. And the great thing about AZ is they title the car as a 1933 Ford which is exempt from any smog controls. So if you meet the State resident requirements it is a great place to register a hot rod.

[SteveP]

Sounds like Az. will be a good place to title and register. I'm not a resident but I think they will go by where the car is kept. If I leave it in Az., they will want it registered there I think.
We have a little patio home in Mesa and usually spend April, May, Oct., and part of November there. We like to ride bicycles on the fabulous trails at McDowell Mt. part and Browns Ranch. Soon I can drive around town in style.