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Author Topic: Fitting rear tire to swing arm odd problem  (Read 1173 times)

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Offline jamesbekman

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Fitting rear tire to swing arm odd problem
« on: July 10, 2013, 07:26:44 AM »
Hi,

So I ran into what appears to me to be a strange problem last night.  I have a 1971 CB 500K0.  The frame was stripped down and painted, swing arm removed and put back on, new fork tubes etc.  Put the front tire on without a hitch, then when putting the rear tire on my brother in law and I ran into a problem.  The long bolt which holds the wheel in place with the castle nut and pin just does not want to go all the way through to the other side.  I have both spacers in that were there upon removal and it just will not pass through all the way to where you can get thread on the castle nut to start to tighten it down and you can see there is still some space between the spacers and the swing arm.  So to try something out really quick we got tie down straps and tried to just rachet it in and pull it together.  When we did that my brother in law unfortunately stripped the castle nut threads... 

Long story short, obviously we are doing something wrong...  Just how wrong?  The bike has comstars on it and those were not stock with a 1971 CB500 bike.  Originally when we were sorting out the bike and getting it running before we stripped it down, the bike was horrible to try and move...  I associated that with a maladjusted drum brake and adjusted the brake and it made it easier to move but not as easy as it should be.  Should I be worried about a bent swing arm or just having a comstar rim with the wrong spacers fitted?  Or am I just blatantly missing something here?  The tire came off easily enough when it was disassembled.
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Offline Xnavylfr

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Re: Fitting rear tire to swing arm odd problem
« Reply #1 on: July 10, 2013, 07:40:57 AM »
Did you notice if the axle was protruding completely out and the CASTLE nut tightened down BEFORE tear down???  I know from experience that the SOHC swingarms are shorter and narrower then those on the 79 and up DOHC models. I believe all the SOHC swingarms looked like it was stamped with 2 pieces then welded together and the seem is lengthwise. The DOHC swingarms look like a pipe slightly curved to allow for the width of the wheel/tire, this swingarm is AT LEAST 2 wider at the axle plates and requires a DOHC axle!!!!  I'll go out and measure both and post measurements later.

Xnavylfr(CHUCK)
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Offline jamesbekman

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Re: Fitting rear tire to swing arm odd problem
« Reply #2 on: July 10, 2013, 07:56:02 AM »
Thats the problem, it seemed like everything was ok when I tore it down.  Pulled the pin, undid the castle nut, but my memory doesnt serve me as to what it looked like when I took the castle nut off. 
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Offline Xnavylfr

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Re: Fitting rear tire to swing arm odd problem
« Reply #3 on: July 10, 2013, 08:23:23 AM »
I went and measured a DOHC and SOHC swingarm  and the BIG difference is at the pivot point, the DOHC frame is about 3" wider than the SOHC. The axle plates on the SOHC (CB750) measured at 9.25" and the DOHC was 10.25". Remove the wheel and measure between the axle plates then measure the axle. The axle should be AT LEAST 2" longer from the shoulder of the HEAD to the end of the threads to allow for the thickness of  the wheel adjusters. You may just need a longer axle!!


Xnavylfr(CHUCK)
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Offline jamesbekman

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Re: Fitting rear tire to swing arm odd problem
« Reply #4 on: July 10, 2013, 08:31:08 AM »
Thanks.  Im stuck at work.  Waiting on the bro in law to text me back some measurements. 
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Offline jamesbekman

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Re: Fitting rear tire to swing arm odd problem
« Reply #5 on: July 10, 2013, 10:34:21 AM »
Ok so I made some headway...  Below is an ebay link to what the axle bolt is supposed to look like for a cb500.

I happen to have two cb500's...  The one with the correct wire wheels has this bolt and spacer pictured below in the ebay add.

The one with the comstars has a spacer on the right side that looks different than the one pictured and does not have the ridges pictured.  But it might be the same length.

The axle bolt on the bike with the comstars also has a totally different axle bolt that is a hex pattern on the right side, not a circle as pictured in the ebay add which is also the same as the other CB500 (chrome circle).

The comstar bike also has a spacer on the left hand side as well which I would say would be about 2 inches.  Is that supposed to be there?

http://www.ebay.com/itm/1971-72-HONDA-CB500-CB-500-FOUR-K0-K1-USED-OEM-REAR-WHEEL-AXLE-BOLT-SPACER-NUT/330895090291?rt=nc&_trksid=p2047675.m1851&_trkparms=aid%3D222002%26algo%3DSIC.FIT%26ao%3D1%26asc%3D261%26meid%3D8978447471158603487%26pid%3D100005%26prg%3D1088%26rk%3D4%26sd%3D150619661774%26

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Offline Bankerdanny

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Re: Fitting rear tire to swing arm odd problem
« Reply #6 on: July 10, 2013, 11:12:32 AM »
Since you are fitting a Comstar to a bike that never came with one you can't simply look at the setup from the bike it came from and assume the same will apply to yours.

You may need to measure key parts of the two hub (stock and Comstar) like the width of the hubs with and without the sprockets, the length and thickness of the axles and then mix, match, and fabricate.

The Comstar can work on the SOHC 500/550's, I've seen them, but you will have to be creative. You are asking for off the shelf solutions to a custom problem.
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"The problem with quotes on the Internet is that you never know if they're true" - Abraham Lincoln

Current: '76 CB750F. Previous:  '75 CB550F, 2007 Yamaha Vino 125 Scooter, '75 Harley FXE Superglide, '77 GL1000, '77 CB550k, '68 Suzuki K10 80, '68 Yamaha YR2, '69 BMW R69S, '71 Honda SL175, '02 Royal Enfield Bullet 500, '89 Yamaha FJ1200

Offline jamesbekman

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Re: Fitting rear tire to swing arm odd problem
« Reply #7 on: July 10, 2013, 12:20:35 PM »
These came mounted to the bike when I bought it.
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Offline Duke McDukiedook

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Re: Fitting rear tire to swing arm odd problem
« Reply #8 on: July 10, 2013, 12:33:29 PM »
I would have problems trying to put a tire on a swingarm too, makes no sense.
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Offline Bankerdanny

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Re: Fitting rear tire to swing arm odd problem
« Reply #9 on: July 10, 2013, 12:43:36 PM »
That doesn' t mean it was set up correctly. I just did a quick scroll through your other posts. If I read correctly you acquired both of these bikes as non-runners. So it is possible that the PO (prior owner) fitted up the wheels, but never got them to work right and just let the bike sit until he sold it to you.

My advice is the same, start measuring. You are fortunate to have a 2nd stock bike to use for comparison.
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"The problem with quotes on the Internet is that you never know if they're true" - Abraham Lincoln

Current: '76 CB750F. Previous:  '75 CB550F, 2007 Yamaha Vino 125 Scooter, '75 Harley FXE Superglide, '77 GL1000, '77 CB550k, '68 Suzuki K10 80, '68 Yamaha YR2, '69 BMW R69S, '71 Honda SL175, '02 Royal Enfield Bullet 500, '89 Yamaha FJ1200

Offline jamesbekman

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Re: Fitting rear tire to swing arm odd problem
« Reply #10 on: July 10, 2013, 12:55:54 PM »
That is correct Danny,  He had a 550 tank, and exhaust on it as well... 

Ive been looking for a decent pair of spoke rims/tires/hubs that I can polish up but I keep on coming up dry on something decent.
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Offline Bankerdanny

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Re: Fitting rear tire to swing arm odd problem
« Reply #11 on: July 10, 2013, 02:41:34 PM »
The 550 tank and exhaust are no biggie since the 500 and 550K frames are the same and I think the engine is mostly identical as well, so those two should bolt right up.

Are the wheels on your other 500 no good? Don't assume that just because there is rust that the wheels are bad. I am constantly surprised with how nice an initially junkie looking wheel turns out to be once an appropriate amount of elbow grease is applied.
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"The problem with quotes on the Internet is that you never know if they're true" - Abraham Lincoln

Current: '76 CB750F. Previous:  '75 CB550F, 2007 Yamaha Vino 125 Scooter, '75 Harley FXE Superglide, '77 GL1000, '77 CB550k, '68 Suzuki K10 80, '68 Yamaha YR2, '69 BMW R69S, '71 Honda SL175, '02 Royal Enfield Bullet 500, '89 Yamaha FJ1200

Offline jamesbekman

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Re: Fitting rear tire to swing arm odd problem
« Reply #12 on: July 10, 2013, 08:27:54 PM »
Funny you should ask.  I was actually just starting to polish the wire wheels on the other cb500.  That one we are riding as is while we do all the work on the other bike. 

I was able to take some measurements and a few pics.  I'm on my iPhone right now so I'll post pics tomorrow. 

Both cb500 swing arms measure the same length of 10 inches between the middle of both adjuster nuts that stick out of the back.

The axle rod in question measures 11inches.  The hex attached to it is 22mm

The right side spacer measures 1 3/4

The left spacer measures 1 3/8 after it is taken out of the recess it sits in.
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Offline jamesbekman

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Re: Fitting rear tire to swing arm odd problem
« Reply #13 on: July 11, 2013, 07:17:40 AM »
It looks like my axle bolt is an inch too short compared to the ebay link I attached. 
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Offline lucky

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Re: Fitting rear tire to swing arm odd problem
« Reply #14 on: July 11, 2013, 10:26:55 AM »
You might need to get away from your brother in law.
Stop forcing things together with force.lol..lol.lol

Another CB750 axle ruined. Soon there will be none available even on Ebay.
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Offline Bankerdanny

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Re: Fitting rear tire to swing arm odd problem
« Reply #15 on: July 11, 2013, 10:55:45 AM »
Fortunately he has a 550, so no 750 axles were injured in the making of this problem.
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"The problem with quotes on the Internet is that you never know if they're true" - Abraham Lincoln

Current: '76 CB750F. Previous:  '75 CB550F, 2007 Yamaha Vino 125 Scooter, '75 Harley FXE Superglide, '77 GL1000, '77 CB550k, '68 Suzuki K10 80, '68 Yamaha YR2, '69 BMW R69S, '71 Honda SL175, '02 Royal Enfield Bullet 500, '89 Yamaha FJ1200

Offline jamesbekman

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Re: Fitting rear tire to swing arm odd problem
« Reply #16 on: July 11, 2013, 11:08:16 AM »
Oh he has done a silly thing or two and so have I.  But this is the way it came when I bought it.  The more I think about it the more I dont even think the cotter pin was there when I took the rear tire off.

The axle rod still beeees guuuds if you want I can mail it to you.  Its purty.  I hit it up with the wire wheel and even buffed it cuz I was bored. 
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Offline kghost

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Re: Fitting rear tire to swing arm odd problem
« Reply #17 on: July 11, 2013, 02:17:31 PM »
Lots of people cobble rollers together out of whatever is on hand.......

A roller frame is easier to move around a shop.

Doesn't make it ready to ride.

Hope you get it sorted.....
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Offline tino montreal

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Re: Fitting rear tire to swing arm odd problem
« Reply #18 on: February 14, 2014, 07:30:54 PM »
I may post some pics.
Starting this same conversion...comstara on 1973 cb500f ...
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