Topic: How to Bob Rear Fender on CB550

[ironandtime]

Hi All, I'm a newbie here in the group, and I am anxiously awaiting my recent Craigslist find to arrive here in San Jose CA: a 1978 Honda CB550. Hard to find those around the Bay Area as of late, so I searched further afield and found a solid one in Portland. The total cost for the bike and transporting it is less then many bikes I've seen for sale on CL or eBay, so I feel lucky. The bike is all stock and runs good.

I am not planning on doing a total tear down and rebuild, but instead will selectively modify to come up with a stock-modified combo that fits my taste and needs. One of the things that I know I want to do is to 'bob' the existing chrome rear fender if possible. How does one go about doing that, i.e with the chrome? If I want to keep it chrome, is there a way to do it without having to have it re-chromed after cutting? Or, am I better off leaving the fender pure, and simply purchasing an aftermarket one? Any and all thoughts are much appreciated! Cheers, Matt

[mrbreeze]

I just used another fender to graft to the one mounted on the frame. Cut the bottom off the one on the frame and the bottom of the donor. Set the new bottom on top and screw in under the seat. You have to trim the part by the mount just where it rolls up. Hard to explain but it looks fine with the seat down. Nothing show quality!!

[ironandtime]

That's a great idea, and it does make sense to me...I do appreciate it!

[FunJimmy]

Matt,

Sounds like you found a good platform.
Avoid rushing in with all the compiled project influences and figure out what's right for you. Good bikes evolve into the best combination of parts and format for your riding.

It's a fun journey.
Enjoy
FJ

[ironandtime]

Thanks FJ - I think you are right. I'm excited to jump in and make things happen, but this is a long term endeavor and so doing it right and enjoying/learning from the process is key. Cheers

[Bootlegger56]

++1 on the MrBreeze method or if you do not have a spare fender you can just chop the end that goes under the seat and move it up.  A couple of easy spacers (nuts or pipe) with carriage bolts between the frame fender mount and through the top of the newly trimmed fender and your in business.  If you have a stability problem from the sides you can do as I did and put longer bolts in the grab bar mounts and extend them through the sides of the fender.  Nothing shows after the seat pan is back on.

[ironandtime]

Thanks, Bootlegger, that's a good tip! cheers

[riverfever]

I cut about 4" off my rear fender and then did just that...used some spacers and longer bolts under the seat. I re-drilled the sides of the fender (had just enough room) and bolted it to the frame in the factory location. I have just enough room left to mount turn signals there as well. It's not show quality but the fender had some minor dings in it anyways.

[Bootlegger56]

My donor fender was junk too.  I bought it from a local bike shop for five bucks and saved the original which was in good shape just in case some future owner wants to return the bike to stock.  I sandblasted it after I cut it off and filled and fiber-glassed the holes and dings.  Of course that only applies if you are going to paint it.  I did basically the same for the front fender too except I cut all the bead off the sides and shaped the nose and tail.  That way I got to keep the fork brace function that the original provides.

[WhyNot2]

I'd like to see some pics of these mods.....pleeeeezzz?

[riverfever]

I don't think I took any pictures during the cutting process but it wasn't really all that eventful. There is a little triangular shaped piece (where a bolt connects it to the frame on each side). I used a hammer and dolly to flatten that out on both sides only because it made life easier when bolting it up. That's also the area where I'm going to mount the turn signals.



The view from behind. It wasn't all tightened up here so it looks a little off. I plugged up the holes where the stock brake light was.



This is before I bobbed it. I used some nylon tube (had to drill it out slightly for the new bolts) as spacers under the seat so that I could easily file them into the curved shape of the top of the fender.



I'd like to try making fiberglass fenders down the road. Then I can do the body work on both of mine and fix the small dents and still have that factory rolled edge.

[ironandtime]

Thanks riverfever for the tips and pics, that's really helpful. Once I get to that stage I'll post some pics of how it turns out.

[Bootlegger56]

Sort of the best I can do for now pic wise.

[ironandtime]

Bootlegger, thanks for the pic. That fender looks great, as does the whole bike - well done! I'm loving what you've done. Are those 'euro' bars? Love that seat as well....

[Bootlegger56]

Superbike bars with an inch off each end.  The seat is a stock cut down and re-formed that still hinges and opens like a stock.  This was a real budget minded build.  Us "PO" people gotta survive!

[ironandtime]

Bootlegger, - looks great. I will be switching out my stock bars with euro ones, and I am also planning on re-doing the existing stock seat and pan as well. Probably very similar to yours as far as thickness, but probably ribbed like the seat on this 350 in the attached photo.

[Bootlegger56]

I like the 350 with the butt bump on it.  I contemplated it with mine but thought that the next owner might want to go two up.  Sleeping bag mat makes a good starter layer.  Its not hard to cut the stock seat down. Once you get the old foam off you can see all of the humps and bumps that can be smoothed and trimmed down.  If I had it to do over I would have turned the pan upside down; pulled all the mounts and fittings and put a thin sheet of poster board inside it and used it as a mold to make a fiberglass one.  It would have saved weight and probably been easier than chopping, welding and filling the stock pan.  Shoot me some pics when you get er done!

[ironandtime]

Briliant! Yeah, I am unsure of the back hump..might just go ribbed all the way across so that I can go 2-up when I want to. I'm hoping to use the pan and just cut'er down and recover. Probably will get someone to do that part for me so that it looks right! cheers

[heymak]

buy an alloy mudguard (fender) from ebay cut to length drill 2 holes and bolt to bracket under seat fit bobber light and number plate bracket, easy even for me a 1st timer

[ironandtime]

Thanks, heymak. Nice looking bike!

[WhyNot2]

I know this thread is old, but I finally got around to bobbing the rear fender on my CB750.

[newday777]

I know this thread is old, but I finally got around to bobbing the rear fender on my CB750.

You really need to rethink this....
Your middle picture shows you have it too low to the tire, which will contact the fender hitting bumps of the smallest size.

[Kelly E]

I bobbed my CB 550 rear fender but kept it in the same arc as stock.

[WhyNot2]

I know this thread is old, but I finally got around to bobbing the rear fender on my CB750.

You really need to rethink this....
Your middle picture shows you have it too low to the tire, which will contact the fender hitting bumps of the smallest size.

Yep, that was taken before I raised the rear shock up a couple of notches.

I'm 212, and it rode smooth, and did not hit. Even at 80 mph.

[Don R]

 I had a 750 fender that was damaged by a sagging rear rack, I drilled the spot welds and removed the damaged section, then re-attached to the reinforcing bracket by plug welding under the Lucas taillight.