XT600 Rear Suspension
 

Hi there. I own an XT 600 1989' (2KF). I 've made some improving modifications, or at least, that's what my intension.

I 've made a front suspension swap, with a full front end from Yamaha YZ 125 1990'. Upside down forks, 41mm (the red anodized ones), 300mm stroke. I have also changed the (tiny motocross) disc, along with the caliper, but that's irrelevant to my major concern right now.

I 've found a real bargain, an Ohlins rear shock from TT 600 S, 270mm stroke (the so called "Belgarda") with the UpsideDown Forks, not the "new" one with the conventional Paioli Forks, the TTR 600. I 've chosen the previous TT 600 Ohlins, cause it was -almost- a perfect match with my stock XT 600 shock, in both upper and lower ends (eyelet-hole on both sides, frame and swingarm linkages).

Here's the deal. Both shock absorbers, measure the same distance, 40 cm (400 mm) from upper, to lower eyelet. So, I thought I 'd just enjoy a better shock experience, without changing at all the geometry of the bike. Fact is, the YZ 125 front end, is not just a longer stroke fork, but it seems to be a longer-bigger fork, from top yoke to wheel axle distance. For example, the specific TT 600 that I used it's rear shock, has either a front end with the same "long" stroke (310mm), but for sure it is less "long-huge" from top yoke to wheel axle.

That was my initial thinking fault, same stroke does not mean same overall length of the front suspension. And now my bike is just like a custom, relaxed seat, chopper. The whole foockin' center of gravity is well backed up and down! Of course it's a matter of physics, I don't doubt, but the bike has become reluctant to lean (obvious) and when I ride the seat it gets even worse (pretty obvious too). I 've done some settings, lowered the top yoke (raised the forks through it), but as you 'd expect, no magic solution-balance appeared.

Due to "no dog bones" style of swingarm-linkage-shock, I can't intervene in the bottom part of the shock. So I am wondering about the top linkage (frame). I 've seen a couple of owners who have used, a special extra linkage (between the frame eyelet-hole and the top shock one). It seems that this gadget, reduces the stock distance that the shock mounts, and consequently forces it to "extend", to the only direction it is able-free... vertically...and that's it! The whole back-tail of the bike is lifted up!

Heckhöherlegung xt 600 | eBay

1) Have you ever tried it?
2) Do we have any alternatives in something like this?
3) What do the older-more experienced riders-mechs think about it?

I would appreciate every opinion, thought, idea, whatever helps...


PS. Ohh! I almost forgot. Through my bike "upgrading", I 've ordered a spare swingarm, a bit different. Mine (2KF) has an Iron one, so I bought and fitted an Aluminium one (43F) without disc, but with a drum. The Ohlins shock, is fitted in that swingarm. I am 99% sure that everything else ecxept from the aluminium, are totally same. The linkages, etc. I don't think it could interfere with my problem, bit is's better to mention it...

I bought one of those raiser blocks "Heckhöherlegung" of the German ebay. I needed the extra ground clearence for the things I do, so it has helped me a lot.

I also makes the bike look a bit more "motorcrossy", and not so much a gravel-tourer.

The first ride felt speciel because i sat differently on the bike, but that was it. I tried to remove it once to see the difference but didnt like, so mounted the raiser again.

Mines a 2003 model btw, heres an old pic of the shock removed with the raiserblock:

http://peecee.dk/uploads/122011/heck.JPG

Actually, it was your post in this forum that I 've seen.

Nice photo! Very usefull! I 've already seen another photo of yours, with your "uprised" bike, side by side with a stock one and the difference is pretty clear.

I can assume (from the above photo) that with that "gadget" installed, the top mount eyelet-hole, it "turns" 90 degrees and mount "vertically" in the "Heckhöherlegung", cause the "Heckhöherlegung" itself needs to mount the same way the shock did in the frame...(hope didn't confuse you)...

Anyway. I followed your initial link, I did found a reference to that "product", but it's not available right now, nowhere, nor the german ebay, or anywhere else. Pretty sad...

I have to thank you for the detailed photo. Suppose, you don't know any other place-eshop, whatever, that I can buy something like that...

I think that you can easily reproduce this just cutting a square section metal bar with the same sizes, would be really easy.

But before to do it, please verify how much you can extend the swingarm, before the leverage parts touch the frame. You could find that you cannot do a lot, maybe not more than one cm. Please note that it's better not having the linkage smash the frame at the end of its travel, to avoid frame cracks.

Before to start disassembling, I would work with paper and pencil, and do this:

check the distance between center of front wheel axle and top of fork tubes of the old fork, and compare to the size of the YZ one. You will get a difference. This is what you have to compensate. Then you can start to plan how to do this, as there are a few ways.
I had the same issue swapping a WR250 front end to my TT350. In my case, I extended the length of the frame tube (top side).

http://www.bikepics.com/members/b4nz4i/92tt350/

A more expensive but ultimately much better option would be to get a specialist to make you up a longer shock. If your budget could stretch to it you could get one with a ride height adjuster so you can fine tune the geometry (and get the forks sprung and valved to suit...)

Nice bike, Cyberzarbierindeed man...
I 've just measured the distance (wheel axle-top yoke)...:helpsmilie:
My stock XT 600 forks = 86+ centimetres
My new YZ 125 -//- = 91- -//-

Total difference = ~5 (five) centimetres.....(46-48 milimetres to be exact)

Regarding that even with the stock-factory front end, the back part of the bike was -already- kinda low and a lot of users without changing the front end, they although did fit an aftermarket shock (usually longer), I must be in seriousl trouble with 5 whole cm added to the equation...:confused1:

Please, let me be as noob as it takes...

I am watching at the interesting photos of Cyberzar. I am trying to understand, how the linkage works under load and what affection would happen if we were trying to fit a longer shock in the specific stock distance. I assume that the upper part of the swingarm linkage (the one that is facing backwards, to the rear wheel) should tend to touch the swingarm itself. For example, in Cyberzar's bike, there is a tiny little space (...about couple mm?) and is almost touching the main body of the swingarm. Suppose it is on the limit, on the edge of extension? Does this happen due to the longer shock? Or this is the "typical image" of a swingarm linkage, even with the stock-factory rear shock? (...please...try to be polite with a...non expert)

I 've taken some photos from my bike, although it's late evening here and the quality is not ideal, and I 've found that I too have an almost identical "image" of my upper part of the swingarm linkage. Almost touches the main body of swingarm. Is that a bad sign? Do I have any more "room" for a longer shock, or not? I 've also tried to take a photo of the lower part of that bloody swingarm linkage (tired of this worddoh). Seems there is more "room" in the bottom (I 'say -at least- 1 cm). Maybe I am lucky enough, and that specific space, between the lower linkage and the main swingarm body...defines the spare "room" I can take advantage?

(I 'll try to upload couple of photos)

Last one. What do you Cyberzar mean by:

"I extended the length of the frame tube (top side)."

In which direction? backwards? up verical? Any photos, please?:innocent:

Thanx again for sharing knowledge...

OK, Cyberzar. Think I got your point of modification.

I misunderstood about your bike. Thought it was an XT 350 and along with your WR front end, you also fitted an aluminium swingarm and that your reference about "extended length of frame tube", was about the rear shock mounting and I was trying to figure in which direction...blah-blah-blah...

Man! I am possesed! I always see -only- shock problems! Whatever I read, I think it's relevant with my shock problem:oops2:

PS. I am about to go to a machinist and order an exact copy of that damn thing. Hope he can build it...

+1 on that, there's a guy here in Australia who mods any Ohlins shock to hearts requirements, longer shorter, custom spring & valve.

It may seem an expensive solution but as my old fella used to say,,,"son, do it once & do it right" and he was right of course.

Search Google for KTM shocks (Ohlins) they are cheap as shit in the US, i was getting them for $30 to $50 a shot, get one longer than you need & they can shorten it pretty easy.

http://members.iinet.net.au/%7Emezo/...n%20Shock1.jpg

Mezo.

Hi Mezo. You are another one of my "heroes"bier Your XT revival project was my main inspiration, to restore my old and very first bike of mine. For over 7 years, I 've been cheating my beloved 2KF, with a modified YZF 1000 as a streetfighter. But now I am back:thumbup1:

I 've been looking for a long time about these types of rear shocks. You can find some excellent bargains. That's true. But in my set up, I 've left in it's place my stock airbox and as you can imagine...it's pretty difficult to suit a shock like that (with the bottle gas in side-top of it's mounting), into that restricted area.

Note that, I don't fix-repair-upgrade my bike in the back yard of my house, with my tools in my garage. Mostly I pay for everything to get done and truth is, I don't wanna spend a "fortune", cause I can't afford it. I 've paid for buying this shock, rebuild this shock, installed this shock. It's a pitty to just abandon any chance of setting it up correctly to my needs.

Anyway, nice to "see" you arround.

Remote reservoir?

...R U talkin' 2 me???....................:smartass:

Yeah, I 've fitted an Ohlins from TT 600 1996, with Remote Reservoir. Very handling...

I think you'll find KTM use WP suspension. Arent Ohlins part owned by Yamaha?

Used to be, for ~20 years. Ohlins is independant again, I think from 2008.

I 'll stretch all my options about the -already- fitted ohlins shock.

I keep this alternative solution (WP or other shock) back in my head, in only case I will fail to adjust the existing -nice- shock.

Nice you could use an old post. :)

Yeb, I understand, you simply twist the origial mountinghole 90 degrees. I out a screwdriver through the hole, and turned it, really simple :)

Yep remote reservoir is the way on XT`s as there's no room for the can hanging off the side, those shocks were on a DR650 project bike.

One my latest 34L projects (slow one) one of the bikes came with an Ohlins shock (was used in desert racing) with remote reservoir clamped to the frame.

http://i916.photobucket.com/albums/a...UILD/883_3.jpg

Standard shock next to the Ohlins.

http://i916.photobucket.com/albums/a...ILD/883_13.jpg

Mezo, and thanks for the compliment, dunno about "hero" but hopefully an inspiration for others to have a go at restoring.