Case mating

Bottom End (crankcases and crankshaft)
Post Reply
Rammy
Former member
Member
Posts: 119
Joined: Wed Sep 03, 2003 6:24 am
Bikes: -
Been thanked: 1 time

Case mating

#1

Post by Rammy »

Description: My cases mating surfaces are not perfect and tend to drip alittle.

My cases mating surfaces are not perfect and tend to drip a little.
how much can be taken off here ? can this be done at the home shop somehow, or who can be trusted to do this out there?
Also what is the best sealer to use here?
Thanks guys ???
Cotten
Senior Member
Posts: 6937
Joined: Sun Feb 10, 2002 2:30 am
Bikes: -
Location: Central Illinois
Has thanked: 112 times
Been thanked: 310 times

Re: Case mating

#2

Post by Cotten »

Rammy!

I often encountered distorted and weld-repaired cases that need attention, but could not justify the tangled chain of expenses involved in re-machining. Each one required its own approach.
Please start with carefull inspection.
One method is to ink one side's mating surface with a broad felt-tip pen, and then attempt a rubbing upon the opposite case to determine gaps and blemishes that otherwise may escape notice.
If there is very minor "daylight", and only handling knicks, the cases may be improved by simple lapping of the two together with a coarse compound.

More likely, you will immediately discover highspots and knarfs. A repeated inking and scrapeing of just the highspots (with a decent machinist's scraper) will eventually bring the cases significantly closer to a mate, given enough diligence and attention to detail.
This is time consuming of course. But there will be a minimum of metal removed, and alignment will hopefully not be affected (beyond what a line-hone can correct when fitted for oversize rollers.) Machine set-up would have inherent errors that then require.....more machine set-ups!
If a lot of meat must be removed, then be prepared to grind some thin thrustwashers. I just finished a SportScout where extensive hand-scraping brought the cases together a whopping .020+" (.5mm); I hope the cylinders will go over the studs!

....Cotten

PS: Oh yeah, sealers....I avoid silicones, traditional Permatex, Yamabond4, and anything that gets hard.
I'm sure there are some excellent ones out there, but I use 3M #800 Industrial Adhesive.
Rammy
Former member
Member
Posts: 119
Joined: Wed Sep 03, 2003 6:24 am
Bikes: -
Been thanked: 1 time

Re: Case mating

#3

Post by Rammy »

Thanks Cotton,
I will try thease things. Have you ever heard of a product called Gortex I think it is called , I got a sample of it , neet stuff , comes on a roll kind of like teflon tape.
They say it`s good for machined surfaces . ???
Cotten
Senior Member
Posts: 6937
Joined: Sun Feb 10, 2002 2:30 am
Bikes: -
Location: Central Illinois
Has thanked: 112 times
Been thanked: 310 times

Re: Case mating

#4

Post by Cotten »

Think you will do best to avoid a band-aid solution,

...Cotten
Red55FL
Member
Posts: 88
Joined: Fri Jan 14, 2005 3:35 am
Bikes: 1955 FL on a 54 frame
2012 Heritage Softail Classic
Location: Inola, Oklahoma
Has thanked: 1 time
Been thanked: 1 time

Re: Case mating

#5

Post by Red55FL »

Rammy
Gortex is a good product for sealing wide flanged surfaces. I use it in several places on oilfield equipment.
I would not use it to try to seal the cases as it will extrude into the crankcase and end up in a lot of places in the engine that you really don't want it to be.

Red
Post Reply

Return to “Bottom End / Crankcases / Flywheels”