Author Topic: Junk it or fix it? Case dilemma (Read 1930 times)

nobrake · « **on:** June 04, 2009, 05:10:49 AM »

When I practiced assembling the case I found an opening. More like a slit.
I did notice some welding job on bottom case and less on upper case. If
I had to guess this area was cracked and PO got some welding done. As you
can see upper and lower cases are not even for tight seal. When I clean those
areas previously I did take out good amount of some sort of bondo.

Any ideas what I should do?

Thanks

razor02097 · « **Reply #1 on:** June 04, 2009, 05:13:03 AM »

Not bondo.... probably JB weld...

nobrake · « **Reply #2 on:** June 04, 2009, 05:15:18 AM »

When I scraped that area the stuff was light greyish color.

CB750F2 · « **Reply #3 on:** June 04, 2009, 05:42:44 AM »

It looks to me that some welding has been done causing warping. I had a similar repair done and similar warping. I suggest that you split the crankcases and check carefully, using a straight edge, the areas where bearings sit. Warpage in these areas may mean that the bearings are loose in their housings allowing vertical movement. Replaceing the cases may be the best option. Pat

nobrake · « **Reply #4 on:** June 04, 2009, 06:10:23 AM »

Just checked with a ruler. No visible signs of warping. Perhaps PO
filed that area too much after some welding job?
Opening is about 1.5mm.

bryanj · « **Reply #5 on:** June 04, 2009, 06:17:38 AM »

Not JB weld but DEVCON for aluminium leveled carefully and correct use of silicone will make em useable but unless its a number correct resto of an odd model best way would be different cases

nobrake · « **Reply #6 on:** June 04, 2009, 06:22:21 AM »

Devcon for aluminum

If I built it up with devcon and level them both sides then the case
can be saved?

Thanks

nobrake · « **Reply #7 on:** June 04, 2009, 06:25:17 AM »

http://www.devcon.com/products/products.cfm?brandid=1&familyid=107

This Devcon Aluminum Putty?

nobrake · « **Reply #8 on:** June 04, 2009, 07:47:01 AM »

I have JB Weld. Can I just use this?

I read somewhere here that you need least 3mm for JB. Slit is only 1.5mm.

Someone help

bryanj · « **Reply #9 on:** June 04, 2009, 08:39:35 AM »

Thats the one, its an expoxy like material with metallic filling so its stronger than just epoxy

754 · « **Reply #10 on:** June 04, 2009, 08:51:41 AM »

You dont need 3mm. You MUST have it CLEAN. You may want to start over, to
A, see what you are up against..
B, make sure it is clean and holds, or it may need welding.

Nothing worse than being 500 miles from home and suddenly havving to try to poke back in a postage stamp size chunk of gresay alloy-n-epoxy..

nobrake · « **Reply #11 on:** June 04, 2009, 09:07:49 AM »

All the thanks guys.

I am gonna JB Weld and level as much as possible on both cases.
Assemble the case with permatex ultra copper (rtv stuff).

If it dosn't work then f#$k it. Just my bad luck at first SOHC.

mystic_1 · « **Reply #12 on:** June 04, 2009, 09:20:18 AM »

Sand the area with course sandpaper first, say 150 or so, to create some surface texture where you'll apply the JB weld. This will make it stick much more firmly.

mystic_1

nobrake · « **Reply #13 on:** June 04, 2009, 09:20:55 AM »

Just found a 1976 750 Super Sports on craigslist for 200.00 as for parts.

Mine is 1976 750k. Can I use the SS engine parts for replacement?

razor02097 · « **Reply #14 on:** June 04, 2009, 11:15:40 AM »

I don't think there is a difference in the cases...

WHALEMAN · « **Reply #15 on:** June 04, 2009, 04:32:22 PM »

I would not use silicone for cases. Dan

babyfood1217 · « **Reply #16 on:** June 04, 2009, 05:28:30 PM »

Where are you located? If near Chicago, theres... http://chicago.craigslist.org/sox/mcy/1195399800.html

nobrake · « **Reply #17 on:** June 05, 2009, 05:59:15 AM »

Thanks guys.

Yesterday I spread thin layer of JB Weld on the bottom case ( sanded and cleaned well )
and clamped it down so JB Weld would have strong bond to the lower case. Waited 6 hourse
for it to cure and laid second coat of JB. This time slightly thicker than the opening ( opening was 1.5mm..JB was built to 3mm). Then I applied some motor oil on upper case ( area where it will have contact with JB Weld when two halves are closed ). Used lot of paper towel around the area just in case too much JB squeezed out. Place top case to bottom carefully and bolted down its surrounding.

This morning I unbolted and upper case came off easily.
Oil trick worked well - JB Weld don't stick to oil.
I scraped off excess JB Weld. Visually, it seems it will be nice tight seal but not perfect.

I think it came out descent for my first try.

I was planning to use silicon for super tight seal.
Even with this kind of case repair do you think I should still use 3 bond 1194?

754 · « **Reply #18 on:** June 05, 2009, 09:04:41 AM »

A good method to resurface is to use a file, maybe lathe style.

Keep it CLEAN (use file card) and make sure to remove NO material anywhere else on the cases.

I would not bolt them together with a high spot in there.

mystic_1 · « **Reply #19 on:** June 05, 2009, 11:53:32 AM »

Quote from: nobrake on June 05, 2009, 05:59:15 AM

Thanks guys.

Yesterday I spread thin layer of JB Weld on the bottom case ( sanded and cleaned well )
and clamped it down so JB Weld would have strong bond to the lower case. Waited 6 hourse
for it to cure and laid second coat of JB. This time slightly thicker than the opening ( opening was 1.5mm..JB was built to 3mm). Then I applied some motor oil on upper case ( area where it will have contact with JB Weld when two halves are closed ). Used lot of paper towel around the area just in case too much JB squeezed out. Place top case to bottom carefully and bolted down its surrounding.

This morning I unbolted and upper case came off easily.
Oil trick worked well - JB Weld don't stick to oil.
I scraped off excess JB Weld. Visually, it seems it will be nice tight seal but not perfect.

I think it came out descent for my first try.

I was planning to use silicon for super tight seal.
Even with this kind of case repair do you think I should still use 3 bond 1194?

I was going to suggest exactly this process myself last night, never got a chance to post. With this method you're as close as you're going to get with JB Weld.

Do not use silicon! Use 3Bond or Hondabond. That's the proper sealer for between the case halves anyway.

mystic_1

nobrake · « **Reply #20 on:** June 05, 2009, 01:16:18 PM »

- 10Q

One down........

999 more to go.......

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Author Topic: Junk it or fix it? Case dilemma (Read 1930 times)

WHALEMAN