wondering about chain to frame clearance on my chopper

[emzdogz]

hi folks, hope you all had a good holiday weekend.

I am sooooo close to being ready to tear down for paint. I have a sissy bar bent "loop" coming with tail light mount. Once I sort that, and finalize that's how I want it, this thing is ready tear down for paint, finishing etc.

Not sure why this never caught my eyes before, but yesterday I noticed the clearance between the bolt heads that hold the rear sprocket on and the end of the frame tubing where axle plate mates to it, is not very great. Maybe 1/4" (or maybe even only 3/16ths).

So, going down the road, that just doesn't seem like a whole lot of room. Wheel is centered, and that clearance remains constant when I spin it by hand. (no wobble and wheel is aligned ok)

Wondering what kind of clearances others with a hardtailed frame might have in this area?

There are places too, where the chain is closer than I'd like it, but test riding doesn't show that the chain actually hits the frame or fender or anything, so I think I'm good there.

Anybody got a photo, that shows the left side frame tube where it joins into the axleplate and the clearance between that point and sprocket bolt heads?

thanks!
Em

ps: I did search on this without much luck, thx

 

[Downer]

My frame was tight I had only one bolt rubbing from the sprocket witch was weird anyways I just took the grinder to the top of the one bad one just a little bit my chain was rubbing frame a bit too so I had to put a washer in to make the frame not clamp down so much when I tightened the axel nut

 

[emzdogz]

ok, thanks for the info.

 

[peanut]

theres likely to be more flex in the wheel , hub and frame when riding the bike, especially on cornering. I'd try to get a bit more clearance now if it were me

 

[emzdogz]

would love to hear from others, how big that "gap" is on their hard-tailed bike.

 

[emzdogz]

wow, just found this old thread of mine. I think I need to finish up this bike finally, lol.
http://www.xs650.com/forum/showthread.php?t=10560

 

[emzdogz]

I need new sprockets anyway - might go ahead and use .520 chain. Buy myself a little room..

 

[emzdogz]

I figured out if I move the wheel farther back in the axle slot, it gives me more clearance between bolt heads and frame tube.

To me, now, the problem is that the axle plates should have been welded in differently or the tubing cut differently at the time of fabrication (not by me) so that there was more axle plate in that area, and not yet tubing. Tubing comes back too close to axle slot. So I just need to pull the rear wheel back as far as I can in the slot, and maybe add a link if I have to. (or get a new chain)
I really hate doing that - it looks better shoved up forward in the slot.

So I've finally found a weak spot in this frame.

I went out last evening and compared two stock swingarms I own to the back of hardtail's axle plates. The spacing is exactly the same.

I wish I could get a peek at the clearance between those bolt heads on a stock bike, right there at the juncture where axle "plate" goes into fat tubing of stock swingarm. Thinking it must have been pretty close, too - at least with the axle in front-most position.

I was thinking of adding another 3/4 washer behind the left axle plate, to tweak that side to the outside. But I really hate to put anything under additional pressure, by "spreading" the axle plates more - especially since they are exactly the width of the stock ones.

I guess worst-case scenario is I have to cut this hardtail off and have a better quality one installed by a pro. Back when I got this done, there weren't so many convenient options as now.

lol, at least I have stuff to occupy my mind....

 

[drog]

Hey Em,i just measured a stock swingarm with the stock spacers in place, it has 1 3/16" clearance between the axle plate and top of the bolt head. Distance between axle plates side to side is approx. 8 1/2 ". On my hardtail bike the chain comes close to the top frame bar (approx. 3/16") but doesn't rub. The bolts do not even come close to the frame. Sounds like the tubing is a bit "too long",i.e. "intruding" in the bolts circle.Sounds like an easy fix. If you don't have the ability to correctly notch it,heck, bring it up to my shop and I can put it on my jig and get it properly fixed for you.No problem.

 

[emzdogz]

Hey Em,i just measured a stock swingarm with the stock spacers in place, it has 1 3/16" clearance between the axle plate and top of the bolt head. Distance between axle plates side to side is approx. 8 1/2 ". On my hardtail bike the chain comes close to the top frame bar (approx. 3/16") but doesn't rub. The bolts do not even come close to the frame. Sounds like the tubing is a bit "too long",i.e. "intruding" in the bolts circle.Sounds like an easy fix. If you don't have the ability to correctly notch it,heck, bring it up to my shop and I can put it on my jig and get it properly fixed for you.No problem.

hey there, first - thanks for checking that for me. I think what you said "the tubing is too long" - that's exactly it. The tubing extends too far towards the rear of the axle plates.

I was just making some sketches and I think if I just shove the axle back as far as it can go in the slots, or even back 1/2 an inch more, it will take care of the prob.
"Chain to frame" on mine is about like you what you said - 3/16ths or so, and I've seen no sign of it having hit there. So later when I go home I will try that, and see how much further back the axle can be moved. Might have to get a new chain!

thanks for the offer, Drog! If necessary, I will see about bringing it up to you. As far as notching it - once an axle plate is welded in, is it even possible to cut it back out and reinsert it (or a new one)?

thx again!
Em

 

[emzdogz]

it's kinda like this...this is all very approximate, but shows the general area. The tightness is exaggerated on here some. Also my little sketch shows the chain crooked, but IRL it is straight.

 

[drog]

Nice sketch Em,that's what I thought was the problem. There is no need to remove the axle plate,just nip the tubing where it interferes and weld in a piece of flat stock.

 

[emzdogz]

Great! thanks for the info and helping me think about it.

 

[drog]

I forgot to mention that for more bolt head clearance I used domed head allen bolts,sourced from Gardner-Wescott. They give at least 1/8" more clearance than the ugly stock ones.They can be had in chrome or stainless.

 

[emzdogz]

Good idea on the bolts. Those stock ones really do have humongous blocky heads (which would be fine if not for the clearance prob).
One more question: did you think of going to the .520 chain option?
thx!

 

[XSLeo]

Going to the 520 chain will move the outer edge of the chain 1/8 inch away from the frame.
Just my $.02.
Leo

 

[drog]

Something to consider Em,by sliding the axle back that 1/2" or so you will lose much that much new chain stretch and adjustment. With the price of chains you will want all the adjustment that you can get.Now is the time to fix your little problem properly,before paint,etc. Just my H2O.....And yes,Deacon Blues is from an old S.D. tune.

 

[emzdogz]

thanks XSLeo and drog. Appreciate the input.
I think what I'm going to do is when I take it apart to paint and go over some welds and finish this up (soon) I'm going to go ahead and carefully cut into the part of the frame tube that is on the inside of the axle plate and see how it's put together. I may be able to get away with removing only the rounded tube end. So instead of it having the round tube end, on the inside only that tube will have a squared-off end. Then I can plug it with a small bit of steel, welded in.

Or, drog, if looks like I would screw it up doing that myself, maybe I could take it up to you after all?

 

[emzdogz]

Maybe something like this, to give a general idea.
Left side shows before, right is after.

 

[drog]

You are welcome Em. Your plan sounds good.After the portion is removed you could then replace it with flat stock or even reverse the piece that you removed and weld it back in,as long as it was removed in a clean cut manner.This would give it sort of a "curvey" profile with plenty of clearance. If you trust your own welding/cutting skills enough you can do it,but that is your decision. I will gladly help you out if you need it.I have been doing this type of work since the 1970's and have all of the proper tools and skills to fix it safely.I do this for a living,not a hobby.Your call. Have a good one.I'm going back to work now.