How-to: checking bellhousing alignment / runout
 

Well, this is my first manual trans install and I like to be prepared. My preparations led me to understand that bellhousing alignment is critically important for transmission function and longevity. It should always be verified and adjusted (if necessary) when installing a manual transmission. There are a couple of tutorials out there in cyberspace, but none here. I found out this is pretty easy, the hardest part is setting up a dial indicator.

Step 1: Mock-up your dial indicator so it is located roughly in the center bore of the bellhousing. I didn't think a magnetic base would work, so I fabbed (and I use the term loosely) a rigid piece of metal to firmly hold the indicator and provide a little adjustment. Here's a look at what I made, it bolts straight to the crank and there's a slot for the dial indicator, which I fastened with a 2" bolt and three nuts to adjust it. With the slot I made and the bolt it could adjust in both axis. It's important that the indicator be in the same plane as the mounting surface, and it will fit in the bore.

Step 2: Install bellhousing onto the engine block (without flywheel or clutch) and snug up the bolts.

Step 3: Rotate the crank, finding near center and zero out your dial indicator and make a mark at that location.

Step 4: Rotate the engine about 30-45 degrees (pick one, keep it consistent). Make a mark where you stop and note the runout. Rotate again and do the same until you have marked the bellhousing in a complete circle.

Step 5: You are comparing these measurements against each other in planes. If you have a reading of .010 directly opposite of -.006, subtract one from the other and divide by 2 to determine which way the bore is shifted. In this case, you have .004/2 = .002 or "2 thousandths".

Step 6: Runout should not exceed .010. In my case all measurements opposite each other were less than .010 so I'm good to go. However if your runout exceeds .010 you will need to source bellhousing alignment dowels, which I believe are available in increments such as .007, .014, .021.

If I'm off the mark or missed something please feel free to add to this thread.

Re: How-to: checking bellhousing alignment / runout
 

Thanks! I've always just 'slapped them on' but now I have a much better visual on how to do this.

Re: How-to: checking bellhousing alignment / runout
 

Leevon, you found an A833 for your truck? I have never seen one on an LSx before. Do you have any other pics of your swap?

Ray

Re: How-to: checking bellhousing alignment / runout
 

Yes but I wasn't really looking for it. I had this trans and about three others in mind so when it popped up on Craigslist I bought it. Nicoslam sold two on here the other day in about 24 hours. I sand blasted it, that's why it's so clean, other than than I have no idea of it's condition, just figured if it's bad or I don't like it I can change it out easy enough. Some rock-crawler guy figured out the cheap and easy way to put a GenIII engine to a GenI trans, I just copied his parts so I can't take credit there (not that smart). Here's a couple of pics I have, and if you go to the link to my build below you can see the full write-up.

http://farm5.static.flickr.com/4124/...1433013b_z.jpg
http://farm5.static.flickr.com/4054/...07edd69d_z.jpg

Re: How-to: checking bellhousing alignment / runout
 

Thank you for the link. Your build is impressive and that is an extremely well detailed and informative write-up.

Ray