• Hello Guest, welcome to the initial stages of our new platform!
    You can find some additional information about where we are in the process of migrating the board and setting up our new software here

    Thank you for being a part of our community!

Checking concentricity of a transmission with an integrated bellhousing.

244tiCanuck

244tiCanuck

Well-known member
Joined
Sep 3, 2004
Location
Edmonton
I'm using the PMC Motorsports adapter plate behind my whiteblock to mount a BMW ZF 320, I'm wondering how to check if the transmission is mounted concentrically with the crank. All the info I can find for checking this is for transmisisons with removable bellhousings. Is there a way to do this without tearing my transmission apart? Like, how do FWD/AWD guys do it?

I ask because my car really hangs between shifts, grinds syncros, doesn't want to shift when idling and stopped with the clutch in, etc. It acts super shitty. I've just gotten used to driving around it, but my drivetrain is coming out for some other things over the winter and I want to correct this. The clutch throw is fine.
It shifts great and nice and notchy when the car isn't running. I will be checking and replacing the pilot bearing, but I'm not 100% convinced it's that and want to check if the transmission is even lined up right. A few years ago, I'd just buy another ZF 310/320 and cut it up to check, but DAMN the prices on them has like tripled or quadrupled around here.
 
Does that bellhousing have a hole for a clutch fork? If so, a dial indicator with a magnetic base will work for what you're wanting to do.
 
That's a good question! Just a coffee thought this morn.... did BMW use a dual mass setup with that gearbox OE? I'm reading lots of complaints from folks using the 3 shaft style torque multipliers with single mass flywheels (M90's, et al).
 
culberro said:
Does that bellhousing have a hole for a clutch fork? If so, a dial indicator with a magnetic base will work for what you're wanting to do.
Click to expand...
It has a small hole for the slave cylinder to poke through. Not sure that does me any good, I could MAYBE measure runout, but not whether the crank and trans are concentric
 
244tiCanuck said:
It has a small hole for the slave cylinder to poke through. Not sure that does me any good, I could MAYBE measure runout, but not whether the crank and trans are concentric
Click to expand...
If you can see the dial indicator as it rotates around, then that’s all that’s needed.

Mag base on the crank or fw, dial indicator on the input shaft or machined retainer on the trans. Get as close as you can to the trans. Rotate engine over and the dial indicator will move around the trans part that you’re measuring.
 
Measure distance from dowel (pin holes) to axis centers, both for engine and gearbox.
You might use a bore gauge for this.
Turning a measuring shaft may be needed.

It is not ideal as you only have 2 points to measure, which are almost in line with crank/input shaft but better than nothing.

But, another question, as measuring is one thing:

What is allowable for difference in concentricity and parallelity of both shafts?
 
Last edited:
culberro said:
If you can see the dial indicator as it rotates around, then that’s all that’s needed.

Mag base on the crank or fw, dial indicator on the input shaft or machined retainer on the trans. Get as close as you can to the trans. Rotate engine over and the dial indicator will move around the trans part that you’re measuring.
Click to expand...
I thought about it, there is no way I would be able to see the dial indicator. Then I thought maybe I just mount a gopro on a magnetic mount on the flywheel, pointing at the dial and just record it. I can make paint pen marks with numbers to index from.
 
On all the FWD/AWD transmissions I’ve dealt with (not many fwiw), the bellhousing has been aligned to the block with dowel pins and there’s no way to adjust the alignment from bellhousing to block.

If the GoPro idea doesn’t work, you could try using extended bolts or threaded rod with machined spacers that replicate the factory dowel pins (the spacers probably need to be made on a lathe to be accurate enough) between the block and bellhousing. That would introduce the possibility of deflection/ misalignment in the bolt & spacer system but I think if the bolts are torqued to spec against the spacers it should be okay.
 
andyb5 said:
On all the FWD/AWD transmissions I’ve dealt with (not many fwiw), the bellhousing has been aligned to the block with dowel pins and there’s no way to adjust the alignment from bellhousing to block.

If the GoPro idea doesn’t work, you could try using extended bolts or threaded rod with machined spacers that replicate the factory dowel pins (the spacers probably need to be made on a lathe to be accurate enough) between the block and bellhousing. That would introduce the possibility of deflection/ misalignment in the bolt & spacer system but I think if the bolts are torqued to spec against the spacers it should be okay.
Click to expand...
It has dowels. Sometimes people end up having to use offset dowels.
 
244tiCanuck said:
I thought about it, there is no way I would be able to see the dial indicator. Then I thought maybe I just mount a gopro on a magnetic mount on the flywheel, pointing at the dial and just record it. I can make paint pen marks with numbers to index from.
Click to expand...
They make bluetooth indicators now, displays the reading on your phone and logs it.
 
You must log in or register to reply here.
Back
Top