Topic: Cb550 bent frame

[motopilot]

Hello everyone,

My cb550 suffered a T-bone collision that bent my forks pretty good.
I used a jack to straighten the front tubes back and using a straight edge they looks flush and flat against it now.

I used a level to check the head and it looks off by a good amount. Is it time to get a new frame or am I using the level wrong?

The tubes were only 1/8” bent after my collision.
I didn’t see any cracks in the welds anywhere or chipped plaint other than what is normal for a 40+ year old bike.

[motopilot]

https://imgur.com/gallery/oQSYBBd

[motopilot]

https://imgur.com/gallery/GPmxoqd

Here’s a pic of it before I tore everything down to the frame, with new forks on.

[Old Moe Toe]

I have a 750 frame that was bent pretty bad. The front and rear wheels would not line up by a long way. Also the rear of the frame was not central over the rear wheel, it was like the bike had cartwheeled end over end down the road at some stage. I got a bloke who has a special jig to straighten it out for me and it is now perfectly straight. The difference in riding the bike is enormous. It was not cheap to get the frame straightened and would probably have been cheaper to buy another frame however there were no frames available at the time and there is no guarantee a second hand frame is going to be straight.

[motopilot]

I have a 750 frame that was bent pretty bad. The front and rear wheels would not line up by a long way. Also the rear of the frame was not central over the rear wheel, it was like the bike had cartwheeled end over end down the road at some stage. I got a bloke who has a special jig to straighten it out for me and it is now perfectly straight. The difference in riding the bike is enormous. It was not cheap to get the frame straightened and would probably have been cheaper to buy another frame however there were no frames available at the time and there is no guarantee a second hand frame is going to be straight.

I can only imagine how nice it must ride now, I am worried my bike will be unstable in turns and high speed etc.
All the bikes around me don't have titles and Id rather just fix my bike than go through that whole ordeal at the DMV but if my frame isn't worth it than ill
do what I have to haha.

I live in Minneapolis and the shops iv called either don't do frame repairs or only do it in off season and I would like to get the bike on the road before winter.

[69cb750]

The tubes were only 1/8” bent after my collision.

.125" is not much, frame probably ok.

[motopilot]

The tubes were only 1/8” bent after my collision.

.125" is not much, frame probably ok.

What about the head?

[69cb750]

What about the head?

Take two aspirin and go to bed, 5$ frame is ok.

[Scott S]

 In the pics, it's not leaned over because of the kick stand mount, is it? Do you have it resting level on the lower frame rails...not kicked up on the mount?

[motopilot]

In the pics, it's not leaned over because of the kick stand mount, is it? Do you have it resting level on the lower frame rails...not kicked up on the mount?

The kickstand is removed, in the first pic you can see it’s level across the seat area.

[motopilot]

In the pics, it's not leaned over because of the kick stand mount, is it? Do you have it resting level on the lower frame rails...not kicked up on the mount?

The kickstand Mount is balanced on the other side by a shiv I placed under the frame if that’s what you mean.

[Scott S]

 Then, yeah...if the bottom frame rails are parallel to the ground and the steering neck is bent that much, I'd say that's a problem.

[seanbarney41]

Then, yeah...if the bottom frame rails are parallel to the ground and the steering neck is bent that much, I'd say that's a problem.

I have seen other 550 frames where the pressed steel backbone was bent like a banana in a light, non-life threatening t-bone type accident.
That pressed steel section is not very strong.

[motopilot]

Then, yeah...if the bottom frame rails are parallel to the ground and the steering neck is bent that much, I'd say that's a problem.

I have seen other 550 frames where the pressed steel backbone was bent like a banana in a light, non-life threatening t-bone type accident.
That pressed steel section is not very strong.

Yeah it definitely looks bent when I put the level next to it, when I install the forks and triple tree it looks straight tho as you can see in the pic.

I was only going about 30-35 when I Tboned a car, flew over the hood and broke my foot.

[rosewood]

I had to have my frame head stock straightened here in NZ. There is a guy here that has modified a car chassis jig to work on bikes, it was an expensive exercise.

If you have had a decent hit like you have a described I would start buy checking rear sprocket alignment with the engine drive sprocket with a straight edge or a chain alignment tool. that will confirm that your rear end is good.

Then check your front and rear wheel alignment using a straight edge or the string line method. There are a number of things that could be out on the front end......forks/tubes, head stock, top and bottom triple tress. its a process of correcting and eliminating each one which sounds you have started already with your tubes. Even if your wheel alignment checks out the rake angle could still be out and bent triples could also be masking another problem. From your pics the head stock definitely needs some attention.

     

[motopilot]

I had to have my frame head stock straightened here in NZ. There is a guy here that has modified a car chassis jig to work on bikes, it was an expensive exercise.

If you have had a decent hit like you have a described I would start buy checking rear sprocket alignment with the engine drive sprocket with a straight edge or a chain alignment tool. that will confirm that your rear end is good.

Then check your front and rear wheel alignment using a straight edge or the string line method. There are a number of things that could be out on the front end......forks/tubes, head stock, top and bottom triple tress. its a process of correcting and eliminating each one which sounds you have started already with your tubes. Even if your wheel alignment checks out the rake angle could still be out and bent triples could also be masking another problem. From your pics the head stock definitely needs some attention.

     

Oh man so I’d have to put the engine back in and install the rear tire?

All things considered it seems like my best choice is to just get a new frame.
With that being said, how hard is it to register a frame with out a title? All the ones Iv seen for sale don’t have titles...

[754]

I would make sure its leveled off the  swingarm pivot, or motor mount.. make sure the bar or rod is straight..

[motopilot]

I would make sure its leveled off the  swingarm pivot, or motor mount.. make sure the bar or rod is straight..

Ok I’ll try that next,

Yeah iv used a few different straight edges and they all showed the down tubes bent and then straight after I bent them back. I drilled holes in some angle iron and fitted them to where the engine mounts bolt holes are so when I bent the tubes back so the engine mount holes would line up correctly and not bend the down tubes away from the engine bolt holes. Probably not a big deal since they were only 1/8” from being straight...

[Desert-SOHC]

Where are you located?  There is some pretty good frame places around.

[motopilot]

Where are you located?  There is some pretty good frame places around.

Minneapolis, I called a few shops and only one does frame work but only in the off season.
I found a scrap yard with literally 5,000+ vintage bikes and I’ll be going back Saturday to pick up a new(old) frame that isn’t bent. Probably would cost the same to fix mine as replace it with a undamaged one. Plus, give me peace of mind on the integrity of the frame as well.

[motopilot]

I would make sure its leveled off the  swingarm pivot, or motor mount.. make sure the bar or rod is straight..

The swing arm is straight, no bend in the mounting rod either.

[754]

Was it level  , if it wasn't that changes get way the neck looks.

[motopilot]

Was it level  , if it wasn't that changes get way the neck looks.

I suspected the initial level test I did on the head was off because of a bump in the weld that wasn't allowing the level to sit flat against the head. Yesterday I put the font forks on and made sure the top of the frame where the shocks mount and the swing arm were both level, I measured the distance from the fork axels to the lower engine bolt mount and it was exactly 20" on both sides (which is the correct distance I found from another forum post, if it was less than the down tubes or neck would have to be bent.) The forks were also level vertically, I also centered the triple tree with the spine on the frame and checked the forks level horizontally in the lower, middle and top of the forks, which indicated level as well.

I measured the ends on the swing arm where the real wheel axels are mounted to the same lower engine mount bolts on the down tubes on both sides and they were both the same distance, which shows there's no twist in the vertical axis of the swing arm. So I think from all the measurements iv taken it looks ok across all axis. 

I also measured the head holes to make sure they were not warped into an egg shape and they check out as well. I used a right angle to measure the triple tree too and that checks out. 

everything looks symmetrical and level to me. Anything else I should look for before I start to build?
At this point I don't know what else to look for, and iI'm starting to get analysis paralysis.

[motopilot]

https://imgur.com/dFbinTS

Heres what my bike looked like after the wreck

[rosewood]

Best way to measure head stock is with a couple of cone fittings and a rod once the rest of the frame is leveled. 

[motopilot]

Best way to measure head stock is with a couple of cone fittings and a rod once the rest of the frame is leveled.

I’ll try that next

[motopilot]

welp, I put my front tire on and centered my triple tree (the gap at the top) along my frame spine and my front tire was definitely crooked. So all things considered there is either a problem with my triple tree or my wheel is bent and knowing my frame has sustained a wreck I don't feel comfortable using the frame so im just gonna look for a new frame/bike for peace of mind...