× 1-800-946-2642 Home My Account Social / Forum Articles Contact My Cart
Shop Now
Select Your Car Type Sale Items Clearance Items New Items
 

 Primary gear - extremely scored edition?

 Created by: metalwright
   Forum Width:     Forum Type: 

Found 26 Messages

Previous Set of Pages 1 | 2

 Posted: Feb 4, 2018 09:06AM
Total posts: 6349
Last post: Oct 22, 2023
Member since:Mar 9, 1999
Cars in Garage: 0
Photos: 0
WorkBench Posts: 0
Others have addressed the cause.

File the crank groove like CTR says before just sticking the primary gear back on . Don't muck about with trying to sand the inside of the bushing smooth again or replacing it with another or anything like that. Just stick it back on. Zero problems with using that just as it is.

Yes, I'm a hack mechanic. And yea, you'll probably lose concours points at the next show when they disassemble your motor to make sure your crank is ground to the correct Ra (or RMS if it's a really snooty judge) and they see those scratches. (joking)

Seriously, I would not hesitate to just reinstall it as is so long as you have no other warning signs like too much end float that you can't correct by flipping the C clip or some radial slop.

 Posted: Feb 4, 2018 07:52AM
Total posts: 9241
Last post: Aug 17, 2023
Member since:Jun 5, 2000
Cars in Garage: 0
Photos: 0
WorkBench Posts: 0
US
To elaborate on what Steve is saying, the new bushing will be undersized when pressed in.  It has to be bored to the correct size, preferably on a lathe with care taken to make sure it is running true.  Also, the bore size should ideally be machined to fit your specific crank.  That means taking the primary gear and the crank to the shop that does the work for you so they can get the clearance right.

Doug L.
 Posted: Feb 4, 2018 04:21AM
Total posts: 4134
Last post: Oct 13, 2020
Member since:Oct 8, 2011
Cars in Garage: 0
Photos: 0
WorkBench Posts: 0
US
Mur has it, the C clip grooves take a bit of a beating over time. This pushes up a burr which will cut the rear bushing upon removal. A little work with a jewelers file before removing the primary will stop that. You can buy a new bush and replace that one, be sure someone who know what they are doing sizes the new bushing. Depending on the condition of the front bush you may repalace that one with a floating bush. You may want to inspect the c clip as they wear as well and increase primary end float. I have a fair collection of 998 primaries which I hope some day to have bored to take a 1275 front bush. 

This reminds me I need to order new primaries to go with the new cranks I have to build a few spec short blocks. New crank, rods, cam/lifters, timing set, two part balancer, flywheel and back plate. All in an aged block freshly cleaned, machined and balanced. I guess a new primary would be a good idea. Steve (CTR) 

 Posted: Feb 3, 2018 06:38PM
mur
Total posts: 5840
Last post: Nov 1, 2019
Member since:Nov 12, 1999
Cars in Garage: 0
Photos: 0
WorkBench Posts: 0
It looks like you caught it on the corners of the C clip groove. I know- how can there be corners on a round crankshaft!

You can always drift that out and use the bushing in the 1098 primary gear. Or clean it up.

 Posted: Feb 3, 2018 06:09PM
Total posts: 287
Last post: Jul 8, 2022
Member since:Jul 5, 1999
Cars in Garage: 0
Photos: 0
WorkBench Posts: 0
US
Ok, it seems that area is the bushing..  I'm trippin'.

--trying to set a record for the longest Mini restoration ever!
 Posted: Feb 3, 2018 03:45PM
Total posts: 287
Last post: Jul 8, 2022
Member since:Jul 5, 1999
Cars in Garage: 0
Photos: 0
WorkBench Posts: 0
US
Alright, I'm rebuilding a 1275 A+ to go into my poor Moke because the 1098 is on its death bed, and I had this guy sitting around..

When I got the primary gear off the end of the crank, I noticed that it is scored REALLY BAD.  The crank looks decent in that area, however..

Thoughts?  Just replace this?  No big deal? 

This is my first build, and I am trying to do it on a budget, but I keep finding bad news, like pitting on the pistons, scoring on the middle journal of the crankshaft... And I broke the transmission housing.

--trying to set a record for the longest Mini restoration ever!

Found 26 Messages

Previous Set of Pages 1 | 2