swingarm, Radian or braced stock

[pa23driver]

Color me shallow but putting on a TX750 swing arm is like peeing in dark pants. It will give you a warm feeling but no one will notice. This may be heresy but I have even thought of DIY bracing a stock swing arm just so it looks trick.

not too worried about looks, there'll be engough on the bike to make it look unique, i just care if it improves handling - that warm feeling will be enough when i go into a tight corner.

besides, for 45 bux, might as well while the thing is in pieces.

 

[dwyatt]

No poser points for the TX swingarm for sure, but a good, subtle way to get the job done if performance is your only prioriety.

 

[5twins]

I've also considered bracing a stock one myself. As I see it, the hardest part would be bending that tube loop for the front of the brace without kinking the tube. Well, I discovered the perfect tube loop pre-made - the loop section of a stock frame just behind the rear shocks under the seat. This is the section many cut off and throw away when doing a bobber or tracker. I got mine from a parts bike frame that had no papers. I also cut off various sections of straight tube to use for extending the loop so it reaches back to the axle plates and making the support struts. So, I have all the stuff, I just have to do it, lol.

 

[gggGary]

sounds like both a great idea and a race, I have extra frames and swing arms. First one with pics gets a beer and bragging rights.

 

[oldbiker]

hi guys,, swingarms,,,, a guy in australia put a gsx1100 alloy swing arm in a 77d ,,,and about all he had to do was machine the width of the swinger aera to get it in i recently put 1 in a 1980gs1000e ,,and at the time put it up near the yam ,,and near changed my thoughts,,,,and no frexing and was 1/2 the weight of my steel swing arm...andthey are reasonably cheap to get.... hope this helps you if you use a radian or the 1 made in usa ,,, you also need to make or get a new axle new different size bearings and spacersetc .. regards oldbiker

 

[5twins]

Unfortunately, I'll probably be a "DNF" in that race, lol. I do all my welding outside so I'm about done with it for this season. That doesn't mean I can't fab up the rest of the tubing parts though, if I get around to it. Besides saving the various tubing bits from that frame, I saved the bottom part of the frame that cradled the engine. With this I figured I could bolt a swingarm and rear wheel in then fit up the brace parts to check the clearances. The most important is fitting the brace in such a way so that it clears your chain and brake stay. I'd also like to design it so the stock centerstand could be retained if possible.

 

[XSLeo]

This maybe just a bit off the subject, but it's about a swing arm.
The older Harley's with the 4 speed tranny, they sell a swing arm that has adjustable shock mounts. Instead of swapping shocks to adjust ride height you just move the bottom of the shock on the swing arm.
I have thought that using a square section arm like a Radian you could put a lower shock mount on the arm with holes at different places. Like one over the axle, one about where the stocker is and one about that much father forward.
This way if you want the standard height you use the center holes, the front holes to raise it for a more sporting aspect, or the rear hole for a lower cruiser look. All with just one shock.

 

[jackstraw650]

Color me shallow but putting on a TX750 swing arm is like peeing in dark pants. It will give you a warm feeling but no one will notice. This may be heresy but I have even thought of DIY bracing a stock swing arm just so it looks trick.

Gary.....have to agree with you on this one! I think running the 750 arm makes a lot of sense and will probably do so on my '79, but that triangular tubing brace looks so trick....reminds me of late 70's Superbike racing machines. I actually braced the swingarm on my '79 Suzuki GS1000S[the one bike I have owned that I wish I had never sold!] that way. I'm thinking though, why not have the best of both worlds? Brace the 750 arm! Overkill? I think not.....remember "too much of anything is just enough"!

 

[xstim]

Lots of info. Cool.
Bracing the 750 arm? When do you need to help out the frame? I remember an old thread on a different forum that added some support to the frame in this area but do not remember just what was recomended. Any thoughts on this?
Cheers
Tim

 

[gggGary]

Good point, balance is key I have not heard any complaints about flexing elsewhere in the frame but all things in a balanced manner. My untrained eye says at some point the steering head bracing is not up to modern standards. But the swing arm area (appears) pretty well braced. Again this is for gung-ho track use not typical or even hard street use. If you really want handling, an XS650 is simply the wrong place to start.

 

[jackstraw650]

I have to agree about the swing arm area vs the headstock as far additional bracing goes. Bikes from the 70s were notorious for the "hinge in the middle" handling which was usually caused by four things or, more often, a combination of these four things. They were crap bearings in the swing arm and/or the headstock, flexing of the actual swing arm, flexing at the headstock area, and "fish oil" shock and fork fluid. I remember Cycle Magazine, back in the Gordon Jennings/Cook Neilson era, did an article on bike handling where they stripped a couple of different bikes to the bare frame and mounted them in some sort of fixture to hold them firmly. They then took a long steel bar and slid it through the frame in various places, applying force to a particular area of the frame. They found that the headstock area would actually flex several degrees off center when force was applied through that area. They found the same thing when force was applied between the two "legs" of the swing arms. After that, they started trying to correct these factors one by one in order to affect a handling improvement. The most improvement they found was after they braced the headstock area with diagonal tubes they placed until the area wouldn't flex any more when force was applied from the steel bar. They ended up welding a circular strap around the headstock on one of the bikes in addition to the tubing braces before they could stop the majority of flex in that area. The other part of this improvement came by adding swing arm bracing like we have been talking about. Cycle ended up being amazed both at the poor design of some of these frames and how relatively easy it was to markedly improve the handling with these fixes. You have remember that this was the late 60s, early 70s when the Japanese were having major trouble getting their GP bikes to handle much less the street machines. It wasn't until the late 70s early 80s that Suzuki actually started focusing on handling with the GS series of bikes.
Whoa, sorry guys.....got carried away down memory lanemust be older than I thought! At any rate, bracing the headstock and swing arm on bikes from this era is a good idea.............

 

[5twins]

Yes, you can add additional bracing to the pivot area. It consists of nothing more than a tube between the 2 pivot points, tying them together and to the frame backbone .....

 

[xstim]

Hey, Thanks 5twins. That photo brings it back to me. Do you find it a worth while addition? It seems simple enough, even if you need to get someone else to weld it.

It is good to hear a few others are spending a bit more money on these old bikes than I care to admit to my buddies. I am currently spending a bit on what I call a Cafe lite while I collect parts for a more extravegant rephased 750 cafe. Although I have a daily rider Duc st2, a nice bmwr100s, and a cool rz350 that needs some tlc, these old xs650's have me hooked like heroin.


Tim
xs1b
83 Special
and a few in between

 

[5twins]

I haven't tried the mod myself, just saved the pics in case I want to. I'm pretty happy with my bike as it is now. It took several years doing one mod at a time to get it nice and solid handling wise. The last thing I did was add a fork brace. That was the missing link and really, really helped. I've tried a fork brace on pretty much every bike I've owned. On some they helped, on others, not so much if at all. This 650 really needed it.

 

[xstim]

Hey, Did the fork brace do more than a special's giant chrome fender? I guess I should ditch that monster fender anyway.

 

[5twins]

The fender helps some (I certainly wouldn't run without one) but the brace helps lots more. Just grabbing the front brake and pumping the forks up and down in my driveway, I could see the front tire moving left and right under the fender. The single disc might cause this. Maybe a double disc set-up wouldn't flex like that. All I could think was if it's doing this in my driveway, what the heck is it doing when I'm going down the road, lol.

 

[XSLeo]

I had the 75 fender on the bike, it just didn't look right. I picked up an 79 XS1100 fender. It didn't have the heavy bracing underneath. As far as handling it was like not having a fender. I then got and 82 650 fender, AHHHH much better. The heavy bracing helps.
If you choose not to run a fender at least run a brace. A fender and a brace is best.

 

[Jack]

Yes, you can add additional bracing to the pivot area. It consists of nothing more than a tube between the 2 pivot points, tying them together and to the frame backbone .....

bracing the swing arm pivot points with these types of devices calls for the swing arm to be in place pre-loaded to specs or you'll end up shimming the pivot points to reduce swing arm side play

 

[xstim]

OOHH,
Thanks Jack, I had not thought about that.
Just lost a bid on a tx swing arm, anyone reading this just buy it and want to make a few bucks?
I just put the duc away for the winter and took a short ride on my local favorite twisties with the '84 special What a wobbly old girl. Gotta get the Cafe thing running.

 

[XSLeo]

xstim, have you replaced the swing arm bushings and head bearings? This made a world of difference in my bike. Doing some fork mods and better shocks helped.