Backwards Rear Shocks?

[Liamrdv]

I have an 82 XS400J Maxim, it was converted to regular suspension from the single shock but I guess the guy who had it before me somehow put the rear shocks with an angle facing away from the head of the bike rather than towards it, it feels kind of off and I'm not sure how to go abouts this, anybody have any comments on this?
I can post pics if anybody wants to see, very janky looking set up.

 

[Liamthedevastator]

A photo would be great, I can't picture what you mean. Also, whereabouts on VanIsle are you?

 

[Wolfe_11B]

Oh man I want to see a picture of this.

 

[Greasey Fingers]

........

 

[Liamrdv]

Haha sounds good boys, local mechanic got a good laugh out of it, personally ive never seen anything like this, the previous owner must have made the mounting holes himself and everything, post back in a few minutes.
Also, Campbell River mainly, spend some time in Victoria as well.

 

[Liamrdv]

I'm honestly unsure of what this even does that would be detrimental to the handling, but I know it just doesnt really feel right, it looks like theres mounts for where they should be but I think the previous owner wanted this to be lower and had it that way, which I like , the guy seemed like he knew what he was doing though when I bought it off of him, seemed like a pretty smart and mechanically savy guy. I'm probably going to try to move them to the forward mount today and see how it looks, maybe invest in a pair of shorter shocks because I like feel of a soft tail and I still want it to be low on that end.
Anyone got any thing to add on to that?
Im hoping I can get away with the shocks that are on there already.

 

[Liamthedevastator]

That's basically what I figured you meant, and it really comes down to geometry. There are wizards on here that could tell you exactly what this means, but I'll tell you that you should put them so the are tangent to the swingarm's arc of motion. The reason shocks are generally installed at that forward angle is to transmit the forces directly along it's length. When you hit a bump the swingarm moves in a circular path (due to it pivoting from one point) towards your butt, and the shocks compress and resist that motion, while dissipating the energy from it.

You get the maximum force 90 degrees from the swingarm (this is called a moment arm), which is why the shocks are more or less perpendicular to the swingarm (under compression). Now, the shock is what's called a "two-force member" which means it can't transmit any torques through it. Essentially, the fact that it can pivot around the two mounting points at the end means it can't support any torque and will behave like a shock normally would at weird angles (like the one your setup is at right now).

HOWEVER (and this is big) that doesn't mean the shock can handle the potential for buckling forces. I don't think it is really possible given the small stroke, but the fact that the shock is absorbing forces along a geometry it wasn't designed for (technically close to tangential to the swingarm but gets farther away from 90 as the swingarm compresses, not good) that would be why it doesn't feel right. I imagine it feels sluggish and sloppy on rebound.

You can probably still use them, but give them a once over for bent shafts or cracked seals. I think it would be possible for the odd forces to mess with it a bit. I would definitely move them back to a more "standard" geometric position.

Edit: Just saw the bit about wanting to keep the lower stance. I would do one of two things:

1) Buy shorter shocks. Sucks that you can't use these ones but at least a set that is designed to be short will work awesome.
2) Weld some big posts on there so you can move the mounting point a few inches above the frame

 

[XSLeo]

That is an unusual way of lowering a bike. It may work but it looks odd. And apparently, from what you say, it doesn't function well.
I might try moving the shock forward and see how it works. If it improves things, then try a shorter shock.
Leo

 

[xschris]

I would look for the original swing arm and mono shock the would have come with.

 

[Liamthedevastator]

I would look for the original swing arm and mono shock the would have come with.

Oooh, I understand now. Previous Owner converted it from the monoshock to dual shock. I guess that would definitely affect the ride.

OP, if you want to keep it with the dual shock setup I would move the mounts to a place that better resembles the stock dual-setup, and also check to see if the frame is braced enough to support the suspension load there. You may want to truss up the frame to add some stiffness. That's just my thought though, and Master Guru XSChris has spoken so I'd think about what he has to say

 

[drewpy]

not to mention the amount of force on the end of the frame/swing arm, enough to bend it in a pot hole I recon.

 

[Liamthedevastator]

I'm with you there Drewps. Looking at the photos again I see that the top of the shocks are mounted to the very end of what I'd call the fender mounts; this is probably creating a huge amount of flex which is why the ride doesn't feel right. The torque being created there could cause it to fail.

Liam, I would buy some mounting tabs from Chop Source and get them welded on where the licence plate is currently. Putting the force through that triangle peak of frame will be way better than where it is now. Check to make sure the welds around there are good and put a solid brace across the two sides of the frame like a bridge. May seem like overkill (probably is, I've done no math to support that recommendation) but a good stiff frame will improve the ride and safety if you want to keep the dual shock setup.

 

[Liamrdv]

Right and convert it back to the original you guys are saying, that'd be worth a shot I see now that the original swing arm was chopped to fit the dual shocks and theres some rigged up looking shit on it.
I think I might try to convert it to a more regular looking dual shock, with shorter shocks of course, but I'm not sure how solid the frame is, I see that its hollow across the point where I would have them sit.
Would you guys think it would survive? You can see in the picture, theres a bolt where I've threaded through my license plate I was thinking about moving the shocks to there, pretty well it would be the same strength I believe as where they are now, all I would have to do is drill through the frame a bit more and I would probably install a pin that the bolt would sit inside of for a bit of extra support to brace it on.
Let me know what you think! If not I might have to go back to the original set up at some point when I find the parts at a decent price.

 

[Liamthedevastator]

I would not drill the frame. It's probably under and inch diameter and the mounting bolts are M10. You'd have some kind of failure in no time, most likely the bolt tearing through the frame. I would weld on new mounting tabs or go back to the original monoshock.

 

[Liamrdv]

Thanks Liam, I didnt see your other post before I had responded last thats helpful, anyhow Im looking at the mounting tabs and I see that on XS400J Maxim frame there is already something that looks similar, I will attatch pictures, now it's definitely not the same and im sure its probably not meant for that but it may do the trick if I have something like a hollow pin through it with the bolt through that for extra brace like mentioned above I believe, here I will attach a bunch of pictures I took and maybe you can tell me what you think, it's not directly the frame so it wouldnt rip through the entire frame if anything just that bracket which looks to be welded on, after some research i see that other frames have that same bracket welded on. not sure what its for, between my fingers in the one picture is the hole that I have the license plate bolted to but on the other side.
If all else fails I will get the mounting tabs and have them welded.

 

[Liamthedevastator]

Unfortunately I can't help with figuring out too much more about these frames cuz I have a 77 and am not familiar with anything else. Maybe wait to see what someone with more experience with this year could suggest. My google search showed bikes with both the dual and mono shock setup so I'm stumped. My guess would be that that hole is for some kind of rear hand or brace... but I've got no clue! Could work the way you're saying with a tube to put a bolt through, but I would just as soon buy two brackets and have more points of contact to spread the load. Good luck mate

 

[Liamrdv]

Thanks again for the input, I'm going to give it a shot I'm thinking, I'll post pictures when I'm finished with it, not sure when I'll get around to it, hopefully get a bit more input from folks on here before I move ahead with it.

 

[Liamrdv]

Okay so I went ahead and moved the shocks, I left them on the outside and just drilled out the hole to fit a 3/8th bolt, nice and heavy duty.

It rose the bike up a lot higher than I expected , when I measured it eye to eye, I found that the shocks were about 13 inches, and at the height the lower end was at before, from eye to eye I would have needed 12 inch shocks to keep it looking the same, but I used the same shocks and so it rose up, but honestly it looks like it rose it higher than just inch, but I must be wrong, anyhow this is how it looks now!
Took minimal effort with just a bit of rerouting some wires and what not.
Does anyone know if 12 inch shocks would bring it back down to the height it was at before? Maybe I will step it down to 11.4's.