Bell housing alignment opinion

[hurlbird]

About to put my 4 speed back in... I've become aware of the need to align to the bellhousing/tranny to the crank. Is this really necessary? i cant believe they did that level of precision at the factory.. thoughts?

[pbf777]

     O.E.M. bellhousings are generally pretty close (if not damaged  ), aftermarket you sure better check!   

     Scott.

[csxsfm]

+1

[hurlbird]

gotcha thanks

[98SVT - was 06GT]

I've never done it on a street car or had any problems with the stock parts or scatter shields that were US made. I'm going to check it on the race car but, I'm not looking forward to learning. I have to change the discs to fit my TKO600 dog box. Just too many variables. Multi disc 5.5" Tilton clutch, Throwout bearing mounted to altered aftermarket bellhousing. Yes that's the left side header crossing above the bellhousing blocking the top bolts. The original toploader is looking easier bit it breaks those pretty easily and I'm not a fan of Jerico prices.

[shelbydoug]

About to put my 4 speed back in... I've become aware of the need to align to the bellhousing/tranny to the crank. Is this really necessary? i cant believe they did that level of precision at the factory.. thoughts?

It is not an issue on a street car with a Ford bell. The amount of play in the pilot bushing is greater then the misalignment would ever be.

If you are going to rev your engine constantly 8 to 10 thousand rpm then you need to check everything as always.


In 50 years, I've only had to replace one input shaft bearing. That was on a stolen and recovered 69 Boss 302 that not only did the thief blow the transmission input bearing but they are still looking for the pistons in the trees somewhere.

A shame. Another C8FE block gone to Heaven.


If memory serves me right, that was an issue with the early Lakewood "scattershields" for the 427's? On those you needed to use offset dowels BUT that was MOSTLY because the starter ring on the flywheel would contact the top of the bell house.

That's actually a waste of time anyway. What we would normally do is start the engine and let it run until the sparks stopped coming out. Then it was clearanced. 

[hurlbird]

thanks.. i could not imagine it being necessary for a factory set up.

[Kent]

Where can I buy a good measurement gauge to aligne bellhousings? I cant find a real good tool for that? Or what are you guys using?

[shelbydoug]

I don't think there is a ficture that you can buy that would simplify measuring this.

I'm sure that someone in the past has made one for their own use but I can't think of any off hand that I can send you to.

It just would be a combination of using a transmission input shaft and a dial indicator.

Then you would need to measure the input shaft for straightness and if it is located accurately in the transmission case that you are using, etc., etc., etc.

It's a big deal to do this with virtually nothing to gain.



A failed input shaft bearing would likely be the most significant indication that there was an alignment problem.

I would also SUGGEST that there is a reason that virtually all of the US manufacturers used a BUSHING in the crankshaft rather then a bearing.

I acknowledge that there is a roller bearing that you can substitute for the bushing but I'm not sure that I see the value in that?



Measure the difference between the od of the transmission input shaft and the id of the stock bronze bushing. (NO I don't know it). That should give you an indication of what the acceptable variation should be.

I would think, take 1/2 of that number and that is what the acceptable misalignment is?



It isn't just the dowels that align the bell, it is also the throwout bearing retainer on the transmission as well.

Without a dedicated fixture to plug everything into, this is going to take you days if not weeks to determine accurately.

[OldGuy]

Where can I buy a good measurement gauge to aligne bellhousings? I cant find a real good tool for that? Or what are you guys using?

The best way to determine the alignment of the transmission locating bore of the bell housing is to measure its concentricity with the center axis of the crankshaft. This is accomplished by affixing a magnetic dial indicator base (with dial indicator attached) to the flywheel and "sweeping" the bore (with the dial indicator) by manually rotating the crank shaft one full turn. Ideally, the indicator would read "0" if the bell housing bore was perfectly concentric with the axis of the crank. Naturally this operation has to be completed prior to the installation of the clutch components. Removing the spark plugs also makes the procedure easier. I'm sure that a web search will find a more detailed procedure explanation/pictures.

Frank   

[pbf777]

It's a big deal to do this with virtually nothing to gain.

I and many others would have to disagree.   

A failed input shaft bearing would likely be the most significant indication that there was an alignment problem.

Generally the damage incurred is witnessed at the juncture of the input and mainshafts involving the intermediate bearing and to related improperly loaded surfaces.   

Without a dedicated fixture to plug everything into, this is going to take you days if not weeks to determine accurately.

Please read the post from OldGuy!   

Sorry, I just had to say it!   

Scott.

[Steve McDonald Formally known as Mcdonas]

Old Guy is right. It's something that should be checked but mostly is not because most fall within production tolerances
Ford had a CTP (Certified Training Program) booklet that showed how to check it.
Here is a website that shows how to do it.
A few hours spent checking it can save a lot of headaches down the road
https://americanpowertrain.com/general-bellhousing-alignment-instructions/#:~:text=If%20the%20reading%20is.024%E2%80%B3%2C%201%2F2R%3D.012%E2%80%B3%20so%20use.014%E2%80%B3%20dowels.,offset%20positioned%20roughly%20at%20the%205%20O%E2%80%99clock%20position.

[shelbydoug]

It's a big deal to do this with virtually nothing to gain.

I and many others would have to disagree.   

A failed input shaft bearing would likely be the most significant indication that there was an alignment problem.

Generally the damage incurred is witnessed at the juncture of the input and mainshafts involving the intermediate bearing and to related improperly loaded surfaces.   

Without a dedicated fixture to plug everything into, this is going to take you days if not weeks to determine accurately.

Please read the post from OldGuy!   

Sorry, I just had to say it!   

Scott.

I have no issue. I can agree to disagree with both of you. Not a problem for me.

[98SVT - was 06GT]

Don't be this guy........