JOHN383

I am wearing out the pilot bushing (sintered bronze) on my 66 vette
after 4000 miles. I suspect the bellhousing needs to be aligned better
with the crankshaft. ( I have a dial indicator and mtg bracket that will
bolt to the crank shaft.) How much run out is allowed using a Muncie
4-speed? Are adjustable bellhousing pilot pins recommended for resetting the bell housing alignment vs solid offset pins? I'll have to tap the bellhousing lightly to position for a more precise alignment.

I had this same problem with my 60 vette... alignment problem
and premature wear on the bilot bushing.

Tom Austin

I just finished checking my bellhousing alignment using a Browell alignment tool. Fortunately, my bellhousing was almost perfect. So, now I have a brand new alignment tool - and unused RobbMc Performance alignment dowels availalable (both .007 & .014 offset). Shoot me a PM if you're interested.

Tom

W Guy

I don't know what the specs are, but if you had the mains align honed, that would raise the crank centerline with respect to the bell. Usually those alignment hones are no more than .002".

Verne

JohnZ

You want to keep runout below .005" TIR; adjustable dowel pins (Lakewood, RobbMc, etc.) are easier to work with than solid offset pins.

DansYellow66

[QUOTE=JOHN383;1583448550]I am wearing out the pilot bushing (sintered bronze) on my 66 vette after 4000 miles. QUOTE]

Not to be a wise guy but how do you know, or why do you suspect you are wearing the bushing out? Noise? Chatter? Actual micrometering the bushing bore? GM bellhousing are usually pretty much in spec.

BB767

Tom, you have a PM.

Thomas

JOHN383

I installed a brand new GM ZZ383 engine in this vette, bell housing/tranny was the
Muncie that came with the vette. The new pilot bushing I installed with the engine
and the tranny started to squeal when I held down the clutch pedal...possibly the input
shaft bearing spinning in the housing. When I pulled the tranny this afternoon the new
pilot bushing was about .015 oversize. Same thing happened with my 60 vette... that bell hsg was offset over .020. I later used offset dowel pins to reset... no problems since.

By the way I installed a brand new ZZ 383 in my 60 vette too!

JOHN383

Tom:

Thanks for the offer... I think I'll go with the adjustable dowel pins. I bought the Browell alignment tool two years ago... had much better results with the dial indicator which
took me about 6 hours of tweeking til I got it right.

DansYellow66

Let us know what you find out.

JOHN383

Here's the situation with my runout using a new dial indicator. Pulled out all the spark
plugs to turn the engine at the vibration damper. Started at 0 reading at 12:00, at 9:00
it read .006, at 6:00 it read .005, at 3:00 it read .006. I went around 3 times and it
read the same. Also I used a mirror as I rotated to make sure the indicator wasn't
bouncing around on any nicks inside the circular bore on the bellhousing.

It looks like I need to drop the bell hsg down .0025" to adjust the runout. (Not sure
why I'm getting a .006" reading at both 9:00 and 3:00 but they are both equal).

This doesn't seem like a big problem. I'll have to check for a bent transmission
input shaft too. As mentioned earlier my pilot bushing was worn oversize about .015!
and was brand new 4K miles ago. Anything else I should check?

Thinking of picking up .007 solid offset dowel pins for this minor correction.

DansYellow66

If all of those readings are on the same side of 0 the most you are out is .0025 inch which is well within spec. Looks like the transmission receiver hole may be a couple thousands out of round but I would say the bellhousing is good. If you are getting rapid bushing wear you do need to look elsewhere. Was the bushing still solidly in the crank when you pulled the transmission or did it come out loose?

Plasticman

Have you checked the bell housing for parallelism (per the #1 orange instruction sheet posted by JohnZ)?

What does the surface of the input shaft pilot surface look like? I recently had an input shaft pilot surface repaired, due to much roughness & grooves caused by a failed pilot (needle) bearing.

Plasticman

JOHN383

I did not check parallelism, I guess I should. The input shaft has a small bit of rust about
3/8" from the end... not good but the surface still felt smooth. I plan to have my tranny
guy replace the input shaft with a new or good used replacement and check the shaft itself for straightness (he uses a dual center stand with dial indicator) and has hundreds of used parts and new for Muncie & Borg Warner.

JOHN383

The powdered metal pilot bushing was tight in the crankshaft (not loose). It was very difficult to remove. I used a 5/8-11 tap to extract first, that stripped out and I tapped it
3/4-10 then using a bolt, washer and nut to screw it out. Much tighter in this GM crate
engine than I have experienced in the past. A new bronze bushing is now installed
which required a sledge hammer and special insert toolthat I made to prevent marring
the bushing.

Kerrmudgeon

Just a thought, but when I rebuilt my T-10 the front bearing for the input shaft only had a few ***** left in it! Amazing it ran at all. When I put it back in I had the same problem you have, and it turned out to be a warped shaft from all the years of having a bad bearing. You might check the runout on the shaft on the trans.

DansYellow66

I think I just noticed you to say you had a powdered metal bushing in there last (magnetic I assume). That could have been a part of the problem.

Did you try putting the bushing in a deep freezer overnight and then pull it out and immediately drive it in. Not too surprisingly this makes a big difference in installation effort.