indexing a bellhousing

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  #1  
Old 01-22-09, 03:07 PM
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indexing a bellhousing

Hello, anybody out there have any experience indexing a bellhousing? I'm going to be installing a 5 speed trans. into my 67 firebird and they say it is critical that the bellhousing hole and the crank align (within .005) My old 3 speed saginaw seems to work ok but I want to make sure everything is right before I install the new trans.(Tremec TKO600). When I rebuilt the motor I had it align bored so that in itself would move the crank slightly. There seems to be several methods and tools to do this job.The dial indicator on a magnetic base seems to be the most popular, but there are several special tools available also (pricey though). Your thoughts and experience would be appreciated.
Thanks
Steve
 
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Old 01-22-09, 04:00 PM
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No experience in doing it. This is apparently so the tranny lines up with the crank/flywheel and within .005. That would be close. Then your bell housing doesn't have the alignment pins on it, does it? Do you use an OEM bell housing or is there one with the transmission?

Let us know how you get that done. With that tolerance, I'd like to know what you come up with - sorry I can't help you.
 
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Old 01-22-09, 05:40 PM
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magnetic base and dial indicator would be the best way to check the alignment. but you will need to take either the block or bell housing in to a machine shop realign the locator pins unless you have some excentric dowels

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  #4  
Old 01-23-09, 03:48 AM
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There are dowels on the block that align the bellhousing. If the tolerance if off (which most are I hear) you then use offset dowel pins to correct. If it is way out of spec it can cause shifting,clutch and input shaft bearing problems. This was news to me as I thought the dowels took care of the alignment problem. They say because these components are mass produced they can be way out of whack. The older cars like mine just had a pilot bushing, but the new one uses a bearing. That old bushing may be a little more forgiving if things are off a little. I just thought maybe you guys had run accross this before because I never heard of it until now.
 
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Old 01-23-09, 06:50 AM
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I'd never heard of that before. With the tolerance they're asking for and what most of us have to start with it makes you wonder if the whole drive train has to be rebuilt to make that tranny work. The output shaft would split into the input shaft. Are there tight tolerances coming out the other end?
 
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Old 01-23-09, 07:42 AM
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Little bit of checking around at some HiPo car sites show this as a pretty common question. Apparently .005 is a common spec as well. This seemed like the best solution I found. Of course, still need the dial indicator and such.

RobbMc Performance Products - Bellhousing Alignment Dowels
 
  #7  
Old 01-23-09, 10:23 AM
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I had looked at those dowels from RobbMc before and they do look like the best product out there. Thanks for all the replys. Time to crawl under there and check it out.
 
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Old 02-02-09, 07:34 AM
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Cool

Originally Posted by Gunguy45 View Post
Little bit of checking around at some HiPo car sites show this as a pretty common question. Apparently .005 is a common spec as well. This seemed like the best solution I found. Of course, still need the dial indicator and such.

RobbMc Performance Products - Bellhousing Alignment Dowels
Never had to do the dowel re-locating thing, but I really like those dowels! Thanks for the info.. Will save for later use if needed. I have heard of having to re align the trans. input hole for the crank and input shaft to be in alignment.
 
  #9  
Old 02-13-09, 05:45 PM
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Well after getting the dial indicator on the bellhousing I found that my vertical axis was fine but the horizontal was off by about .006. Some of that was probably due to the block being align bored and moving the crank upward a little. The fix is to install .007 offset dowel pins. The problem however is getting the old dowels out. Pontiacs (at least mine) don't have holes behind the dowels so you can't just pound them out. These dowels are in blind holes. You would think that something that has been installed for only 32yrs wouldn't be that hard to remove-ha, ha!! They would turn with a vise grip but wouldn't come out. I finally ended up drilling and tapping them and screwed in a piece of threaded rod and made a slide hammer of sorts. After heating the area a little and using a BFH they came out. Just thought I'd share my "fun" with you.
Steve
 
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