• When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.

727 alignment

bobtile

Well-Known Member
Local time
5:38 AM
Joined
Dec 2, 2013
Messages
4,606
Reaction score
6,991
Location
NJ
I have a question about mating the trans to my engine.
Upon tearing everything down after the last mishap, I found the converter snout had a ridge mainly on one side.
The trans went out for inspection and whatever else it needs. The torque converter is being sent out for same.
My question is...
Being this is getting another crankshaft and mains, it will be line bored again. How do I check alignment with a 727?
If I had a bell housing from a manual trans, could I use that to check?
Any input appreciated.
 
Yup, both correct above. The variation is in the casting of the case. A dial indicator on the crankshaft to the pump bore is the way to go.
 
I fabricated a mount for my indicator to bolt to the crankshaft flange. I took 4 readings at 90* intervals and purchased McRobb
adjustable dowels to correct the alignment. Mine was out .011". The case will need to be empty so you can work through the bottom opening.
Indicator mnt..JPG
Indicator mount.JPG

Mike
 
Glad I stumbled across this. I just picked up a 1978 727 that has never been seperated from the motor and looks the same way, little ridge on one side of the converter snout. My plan was to use that case to repair another trans, but it sounds like I need to so some checking before using it! Always learn something new on this website!
 
Glad I stumbled across this. I just picked up a 1978 727 that has never been seperated from the motor and looks the same way, little ridge on one side of the converter snout. My plan was to use that case to repair another trans, but it sounds like I need to so some checking before using it! Always learn something new on this website!

Honestly, a trans case not properly centered should show even wear on the convertor hub but significant wear to one side of the front pump bushing....

Wear to one side of the convertor hub actually tends to indicate convertor hub thats not centered..
 
Being an "**** Retentive Machinist", Not only check the radial alignment, check the Axial alignment too!
Ha! You thought this was going to be easy!
 
I've told this story before, but fought 727 front seal leaks for couple months with multiple bushing & seal replacements. End of season teardown, indicated the front pump bore, EGG SHAPED. So indicated the replacement case which was round, but still needed offset dowels to zero the centerline the 727 case with the block.
 
Just spit-balling here
nobody mentioned yet

maybe ?

Bob in your specific instance

I'm wondering if the wear is from ;
the crank moving around, elliptical movements/trust
to one side (the TC is bolted to the flex-plate & that's bolted the crank)
with the cracked caps/vibration etc.
causing it to wear that way

the other stuff mentioned here, is far more common

I wouldn't rule anything out,
especially after the way the motor/engine mains/caps failed

good luck
 
Keep us informed would like to know what was the cause. Also to 493 mike you are one hell of a fabricator.
 
Just spit-balling here
nobody mentioned yet

maybe ?

Bob in your specific instance

I'm wondering if the wear is from ;
the crank moving around, elliptical movements/trust
to one side (the TC is bolted to the flex-plate & that's bolted the crank)
with the cracked caps/vibration etc.
causing it to wear that way

the other stuff mentioned here, is far more common

I wouldn't rule anything out,
especially after the way the motor/engine mains/caps failed

good luck

The scaring on the TC is from the flex plate moving in and out. Showing wear on one side of the TCs "snout" is showing something off center as in the bell housing to engine block. Just like some have encountered with a four speed if the bell isn't checked for center.

Question is, how much side pressure would this create on the crank? Enough for it to self destruct?

(This is new to me as I've never heard of this problem with a automatic. Maybe never looked?)
 
Just found this on the TC of a 727 I recently pulled. I assumed this was some factory machining and never thought of an alignment problem.
 
A really "stiff" flex plate can also cause converter alignment problems.
 
My thoughts of what happened was that the old factory crank that I myself in 3 years that have put over 450 runs on, had some cracks and broke the main caps causing loss of oil pressure resulting in two spun rod bearings.
As Budnicks stated, I'm thinking the (wobbling) crank may have stressed the converter snout on 1 side.
I really don't know...
 
A broken main cap & crank movement would sure explain it. I'd still indicate the case you plan to use. They can be far enough out to cause that problem.
 
clean the paint off the hob end of converter ,put grease on the hub end in the crank for the converter, when all together with no converter bolts installed yet, the vert should turn pretty easy.
 
I have found the converter will still rotate fine with the TC bolts out, even with a significant misalignment between crank centerline & 727 case centerline. My egg shaped 727 housing would have the converter rotate easily with the bolts out. Still badly wore the bushing & allowed the seal to leak. Just say'in.
 
I've measured converter hubs that vary .025". Various manufacturers. Some are sloppy in the crank, some barely fit. My personal car is a tad sloppy. It has never wore a bushing or leaked. It has about .025" total turnout. It has broken 2 flexplates in 600 passes. My bet is it was caused by the rear face of the Mega block being short. The converter sets right on the crank bolts. Starter only engages about 1/2 way into the ring gear. This is the 2nd Mega block I've had like this. This winter I'll replace the dowels and fab a spacer between the block and trans.
Doug
 
Auto Transport Service
Back
Top