CMP Rim Disassembly Tip

[rob love]

I was taking apart a couple of C60 rims the other day, and a couple of the nuts were giving me trouble. The first socket I was using managed to climb over the edges a bit and cracked. I heated the nuts to a mellow red and the second socket still would not remove them all....it eventually cracked as well. So when I went home I got a 3/4 drive 1-1/8 socket and I also picked up a special 28mm impact socket I purchased a while ago.

First a little background. The Canadian MLVWs went away from the rims with the side rings about 12 years ago, and instead started using a bolt together rim, somewhat similar to the CMP rim, with the exception that they used a tubeless tire. When I was restoring my MLVW last summer, I found that the 1-1/8 socket would not do the job, so I got out the calipers and determined that I would be better off with a 28mm socket. That is not an off the shelf item around here, so I special ordered one in. It did the job without issue, and without the need for any heat.

So I decided to try that 28mm socket on these CMP rims. It was a very snug fit, but it took the nuts off the three remaining C60 rims with very little effort.

A 1-1/8 socket is equal to 1.125". The 28mm socket is equal to 1.10236, a full .0226 difference. It doesn't seem like much, but I found it makes a world of difference.

Long story short: try a 28mm socket on your next CMP rim takedown. I think you'll be pleasantly surprised. If you have a modern MLVW, try it on those too.

[Rob Fast]

I'm off to buy a 28mm. Prairie Command BB-Q at my place this Sunday, only 10 to 12 confirmed so far, should be a nice fall day for a glass. Cheers Rob

[rob love]

Yep, just sent Gordy a email confirming my attendance. Talked to Derk.....looks like we've lost him to the other side and he won't be making it.

[Rob Fast]

See you Sun. should be good, home made burgers and potato salad. Bring that quick attach. Rob

[Jacques Reed]

Originally Posted by rob love

.
A 1-1/8 socket is equal to 1.125". The 28mm socket is equal to 1.10236, a full .0226 difference. It doesn't seem like much, but I found it makes a world of difference.

Long story short: try a 28mm socket on your next CMP rim takedown. I think you'll be pleasantly surprised. If you have a modern MLVW, try it on those too.

Hi Rob,

You are spot on with the 28 mm deep impact socket. Had the same experience a while back and got an ABW 3/4" drive, 28 mm impact socket to do the job. Worked great on the end of my breaker bar!

For those going this route make sure also to get the deep impact socket to clear the two longer studs on these vehicles wheels.

Another handy hint is to strike the end of the breaker bar with a heavy soft faced hammer or mallet to protect the tool if you value your tools. The shock loading frees the nut and saves your back too. Out of 6 rims disassembled this way no nuts needed heat and no studs broke using this method. Oh, and my back is still in good shape!

Cheers,

[rob love]

I concur with the use of the deep socket. Mine was from NAPA with the part number of 12628M for the price of $19.59. Worth every penny. I do prefer an impact gun over a power bar though. I think it results in fewer broken studs.

[Tony Wheeler]

Something else I've found makes a difference (with wheel nuts anyway) is to strike the nut after heating, using a length of pipe of suitable ID to slide over the hex and seat on the flange (eg. 1'' water pipe for 15/16" wheel nuts). If you rest the other end on a jack stand you can take a full blooded swing without fear of injury and bash away to your heart's content, which as we know is always highly satisfying! Unfortunately on this particular occasion I had yet to equip myself with the correct tools, and consequently failed to remove a single wheel nut! However I did succeed in testing to destruction two double hex sockets and a 1/2" drive breaker bar, which sheared off through the actual 1/2" square stub. Returning some weeks later with a 3/4" breaker bar and 15/16" impact socket I had no trouble whatsover, although some nuts required the assistance of the property owner, made possible now by the use of a much longer extension pipe of far heavier gauge, from which both of us could hang our full weight and bounce up and down! With that kind of torque I found it amazing that not a single stud broke, which leads to believe that most of the force required is due not to seized threads, but to seizure of the flange surface on the wheel. That might explain why striking the flange directly can often help, so it may be worth trying with seized rim nuts as well. It certainly can't hurt and can be quite therapeutic, esp. if you upgrade to a sledgehammer!

[Richard Farrant]

To us "old school" mechanics who still use Whitworth spanners and sockets, (and measure in Inches) we would use a 5/8" Whit socket for these nuts.
The wheels were to a War Office spec. hence why the British sizes.

The actual hex size is 27.94mm so not much in it.

[rob love]

Ahhh, so that's the explanation of the oddball size by today's standards. I had a look on a chart on this page: http://www.dummett.net/ime/website/i...ner_sizes.html and it shows a difference of under 2.5 thou of an inch between the 28mm and the 5/8 Whitworth/11/16 BSF size. That difference can more than be made up by the layers of paint on the nut.

Just checked the NAPA page, and no Whitworth is listed, although of course they can be had form ebay and elsewhere. I think I'll be ok with the 28mm.