bell housing to transmission alignment - The 1947 - Present Chevrolet & GMC Truck Message Board Network

prg machine · 01-11-2008, 06:31 PM

I have a standard shift cast iron bell bolted up to my small block and the indicator is reading .015 TIR ( total indicator runout) by mounting to the crank and spinning in transmission bore.
i know about the offset dowel cure.................is .015 too much? what should I shoot for?

Thank you.

prg machine · 01-15-2008, 04:42 PM

well I researched ang got it done to within .003......... all of the info i found was that .015 is too much.............bad set up............

apparently GM was willing to take the risk of warranty against the cost of all bell housings and all blcks being within specs.............for us after spending all of our allowances on parts and skinned all of the skin off of every knuckle..............we don't want stuff breaking and clutches having to be changed out left and right.....so buy the adjustable dowels , indicate the bore in to the crank and live with something better than factory.

pretty simple fix........( I guess I answred my own question huh?!!)

JimKshortstep4x4 · 01-16-2008, 03:38 AM

.003 TIR is very good. The accepted practice is to be within .005 TIR.

Good job!

Jim

68gmsee · 01-16-2008, 11:18 AM

Can you educate me? What is TIR adjustment?

68gmsee · 01-16-2008, 01:57 PM

Disregard. I found this site tonight in case there are others that didn't know. I never knew or really thought about this alignment before.

http://www.mr-gasket.com/pdf/bellhou..._procedure.pdf

prg machine · 01-16-2008, 06:55 PM

I was advised to do it as so: drill and tap the block through the side so that 8-32 set screws can tighten and lock the new adjustable dowel pins in place.. They should be very snug, but still be able to rotate.. i turned mine myself and tapped the end for a 3-8 set screw then installed a set screw .. This gave me a method of turning the offset dowel to adjust the bell. once it was as close as i could get it........... I loctied the set srews drilled a small dimple on the side of the dowel for the set screws and tightened them home for keeps!!! worked real good!\

01-11-2008, 06:31 PM	#1
prg machine Registered User Join Date: Jun 2007 Location: oregon Posts: 1,069	bell housing to transmission alignment I have a standard shift cast iron bell bolted up to my small block and the indicator is reading .015 TIR ( total indicator runout) by mounting to the crank and spinning in transmission bore. i know about the offset dowel cure.................is .015 too much? what should I shoot for? Thank you.

01-15-2008, 04:42 PM	#2
prg machine Registered User Join Date: Jun 2007 Location: oregon Posts: 1,069	Re: bell housing to transmission alignment well I researched ang got it done to within .003......... all of the info i found was that .015 is too much.............bad set up............ apparently GM was willing to take the risk of warranty against the cost of all bell housings and all blcks being within specs.............for us after spending all of our allowances on parts and skinned all of the skin off of every knuckle..............we don't want stuff breaking and clutches having to be changed out left and right.....so buy the adjustable dowels , indicate the bore in to the crank and live with something better than factory. pretty simple fix........( I guess I answred my own question huh?!!)

01-16-2008, 03:38 AM	#3
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	Re: bell housing to transmission alignment .003 TIR is very good. The accepted practice is to be within .005 TIR. Good job! Jim __________________ 1971 Shortbox step side 4x4, 350 sbc, 3:07 rear end 1965 Impala SS 400 sbc, Muncie rock crusher 1966 Impala SS 396 bbc, TH 400 1969 El Camino, 350 sbc, TH 350 1971 Snowplow built on a Blazer frame 1972 GMC Short bed, stepside, TH 400, 427 BBC

01-16-2008, 11:18 AM	#4
68gmsee Active Member Join Date: Jul 2007 Location: Centrally located between Houston, Austin and Waco. BCS area. Posts: 7,947	Re: bell housing to transmission alignment Can you educate me? What is TIR adjustment?

01-16-2008, 01:57 PM	#5
68gmsee Active Member Join Date: Jul 2007 Location: Centrally located between Houston, Austin and Waco. BCS area. Posts: 7,947	Re: bell housing to transmission alignment Disregard. I found this site tonight in case there are others that didn't know. I never knew or really thought about this alignment before. http://www.mr-gasket.com/pdf/bellhou..._procedure.pdf

01-16-2008, 06:55 PM	#6
prg machine Registered User Join Date: Jun 2007 Location: oregon Posts: 1,069	Re: bell housing to transmission alignment I was advised to do it as so: drill and tap the block through the side so that 8-32 set screws can tighten and lock the new adjustable dowel pins in place.. They should be very snug, but still be able to rotate.. i turned mine myself and tapped the end for a 3-8 set screw then installed a set screw .. This gave me a method of turning the offset dowel to adjust the bell. once it was as close as i could get it........... I loctied the set srews drilled a small dimple on the side of the dowel for the set screws and tightened them home for keeps!!! worked real good!\



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