Rear Shock questions and Ideas

[Chuck78]

I'm quite perplexed as to your 9-inch wheel travel conundrum. I need to go mock this up after a bit and see where this came from. You never really stated what the limiting factor was or where the wheel ended up, if it was not even close to bottoming on the fender? The shock position never changes except in the top-out position versus stock shock, it lays into the knuckle further in order to extend more than the stock shock. The pull rod links definitely should give the swing arm and rear wheel more ability to travel up higher, as you are changing the initial swingarm position as well as extending the range up higher than what the KDX swingarm and chain roller tab and fender can manage.

[Chopperpilot]

The 9" appear to come from the showa shock. I don't have a wheel/tire on it, I was measuring travel at the end of the swing arm. The limiting factor was the shock bottoming out (with no springs or bumpers installed) the shaft on the shock body. At first, the suspension droop was limited until I clearanced the knuckle/clevis. When I did that I got an additional 3/4" droop vs the stock KDX shock. I didn't see anything other than the shock stopping upward movement. I thought it was pretty shocking too, hence why my next step is to take apart the KDX shock and mock it up the same way to see how it limits travel.

[Chuck78]

The 9" appear to come from the showa shock. I don't have a wheel/tire on it, I was measuring travel at the end of the swing arm. The limiting factor was the shock bottoming out (with no springs or bumpers installed) the shaft on the shock body. At first, the suspension droop was limited until I clearanced the knuckle/clevis. When I did that I got an additional 3/4" droop vs the stock KDX shock. I didn't see anything other than the shock stopping upward movement. I thought it was pretty shocking too, hence why my next step is to take apart the KDX shock and mock it up the same way to see how it limits travel.

Hey chopper,

I was alarmed at your troubled findings here, so I made some time to go down to the shop and test out the same setup using the '98 RM125 shock that I have which I'd pulled the compression adjuster out of and drained all the oil from (drained previously to test the Lainer Suspension aftermarket compression adjuster in).
This is the slightly longer "short-medium" clevis like the DRZ400 clevis. I had to file a bevel on this one still, and wow, it required SIGNIFICANTLY LESS beveling than the shortest of the short clevises on the '01-'04 RM125.

I'm not sure what issue you were running into, but WITH a shock installed this time, I was able to stuff the wheel up basically as high as I was yesterday without it, until the chain tension was giving resistance and almost bottomed/sandwiched between the swingarm chain buffer and that upper chain roller

Pulling out my rear wheel prop and slowly letting down the cinch strap that I've had holding the wheel up to the frame, I achieved around the same amount of wheel travel as last night, now with the 115's.
I had about 12.6" of rear wheel travel with the rocker knuckle linkage topped out against the frame.
Last night I'd measured about 12.75" roughly. I think I didn't have the cinch strap in the same place today which was limiting the tire/wheel.

I swapped back to the 117mm KLX300 links, and it more easily was able to stuff up to full compression/bottoming. I also noted that with this setup, I still actually had maybe just a slight bit of shock shaft travel remaining and unable to be used, so that would be adequate for the foam bottom out bumper.



As far as your issue, I'm achieving very much full travel with this setup, so I'm not sure what the difference is with yours? With no shock mounted, I believe you were mentioning the tire just barely was buzzing the rear fender, and also said you were able to achieve full droop, and with axle all the way back, nearly 14" of wheel travel? So your linkage bearings aren't rusted up and binding...

Which shock body are you using, and when you have the shock length set at 438mm eye bolt to clevis bolt to simulate lowering spacers added (no nitrogen or oil or spring), how much shaft is exposed on your setup?
Is this the RM shock with a redrilled clevis? If so, then there lies your problem.
I believe all the 2005+ Showa shocks with the extra long clevis also have bodies that are 6mm-10mm longer approximately vs the '01-'04 RM125 bodies. And also iirc, you had drilled the clevis a bit further down than you initially estimated?
You need to run the DRZ400 body or '98-'00 RM125/250 or '01-'04 RM125... + a DRZ400 clevis and lower spring seat or the long RM clevis drilled to the distance of the DRZ400 clevis or up to 5mm shorter to mimic the '01-'04 RM125 clevis length.

What pull rod dog bone links were you using in this setup? The only thing I didn't test out here was the stock 112.5 dogbone pull rod links with the long Showa '98 RM125 shock.

[Chopperpilot]

Stock dogbones (112.5), 2003 DRZ shock body, 2005 RM clevis/shaft. And this bothered me so much that I just went back out there after work and checked again....... and I have 12" of travel (without bumpstops/spring installed)! I don't know what happened yesterday that was getting it hung up on something. I still have some beveling to do to get even more droop, and I'll need to clearance the engine case for the spring. From my eyeballing of assembled shocks, I ended up drilling the RM clevis about 1/2-3/4 of a shock bolt diameter longer/lower than the KDX shock length. I think the RM shaft 'sits' a little higher in the body than the DRZ shaft would, due to a top out spring on the seal head that the DRZ shaft doesn't have.
OK, we're back to game on for rebuilding shocks! I'll be re-valving the frankenshowa and gold valving the KDX. I figure I'll run the KDX shock first and after a bit swap in the showa to gauge any improvement using the bigger shock.

[Chuck78]

Ahhhh yes, I had some similar moments trying to crunch numbers and do all sorts of moderately complex tasks and logic late night lol...

If I had no other major projects or obligations, the thing to do here would really be to map out the rear wheel travel vs shock shaft travel with the stock setup (with this NOT starting at zero travel since the custom Showa 438mm shocks will be starting travel prior to the 425mm stock shock), and then with the DRZ shock or RM shock etc, and then compare this leverage ratio data throughout the range with the stock 112.5's, 115mm KLX650 links, and 117mm KLX300 links...


Just based on seeing the orientations of the linkages at full bottomed out compression, the 117mm seems like it should either run a more rubberized type short shock bump stop, or else cut and relocate the upper chain roller mount slightly higher. Granted I'm running 13/49 on that bike, I bet it'd be a slightly lesser issue on my other bike with it's 12/44 or 12/45 due to the chain being just a hair lower.
Based on that, I think I'm going to stick with the 115mm KLX650R links thanks to your priceless tip, chopperpilot!

I figure with the rocker knuckle rotated beyond it's original stock starting position due to a 13mm or 15mm longer shock rotating the rocker knuckle into an even more initially plush position, and adding the 115mm or 117mm links which appear to give more wheel travel per unit of shaft travel over stock, as well as planning to run the axle back about 65% of the way for better steep hill climbing, ALL of the above will soften up the suspension action, so these RM125 shock valving settings perhaps won't even need a significant amount of shim shuffling to revalve, so going with the 117 really is perhaps overkill, as the longer shock / rocker knuckle rotation and 115's will probably give more rider sag to where ride height reduction via 117's vs 115 would not really be needed. My fork swaps on both bikes will be running around 24mm taller than stock, and with an extra plush back end especially on the initial travel, I can get away with running this 4.9kg titanium spring with minimal preload hopefully, vs Race Tech's recommendation of 4.6kg (assuming stock linkage/shock) which I feel on this setup would be incorrect. I was running the stock 5.0 on both bikes, but it was no good for the first few seasons until someone schooled me on not having enough rider sag. After backing the preload off to get 105mm-110mm sag on the 5.0kg stock shock spring, my riding immediate improved significantly. These setups should definitely be softer initially as best as I can tell, I'm thinking that this would allow running a spring on the firmer side of recommended with the preload backed off, which is a trend in recent years all over really, but still benefiting deeper in the stroke with the spring taking up the slack and holding the bike up on moderate hits.


I also may make some 114mm links out of 1/2" 6061 aluminum plate that I've got here, but I'll need to source some stainless steel bushings or whatever metal the bushing sleeves are in these aluminum KLX links. They aren't there as a bushing for friction, they are there as a solid steel clamping surface and impact load surface to prevent the softer aluminum from getting deformed from clamping forces and impact forces. They get clamped down solid to the inner bearing races, and the only lubricant needed is a high molybdenum content paste to prevent wear and tear from the shockloads and minuscule movements. 2 of my stock links and this steel set of 117mm KLX links are seriously worn out, the STEEL versions, so these aluminum versions seem far superior with a much harder sleeve through the bolt holes to better last. These things despite being twice as thick and longer bolts, are still 30% lighter than the steel short stock versions. Add KX500 titanium linkage bolts, and you save like 1.5lbs with the swingarm bolt in ti as well! (yes, I've been slowly dropping abrsurb money into these KDX220's for being a kick start "old dinosaur' bike to some... but those who know, know! With a fork swap and shock revalve, pipe and jetting, they sure do keep up and run with the brand new bikes just as well!

[Chopperpilot]

So are you planning on a DRZ length shock? or are you going with something different? I'm glad I drilled the hole a little 'long' because I figure it gives more room for travel when mixed with 115 links, and more height adjustment to go with front forks. I'd say the setup I'm planning to run is about 1/2 way in between the KDX length and the 2003 DRZ length shocks.

[Chopperpilot]

Technical Touch just got back in touch with me....... I didn't see anything particular for our shock on their site (or my KLX650R, which appear to be the same almost) and asked on a contact form. They replied that they didn't have anything for these bikes. Odd too, because cross referecing the All Balls seal heads, they work on a bunch of late 80' early 90's honda CRs and the later XR series...... I guess All Balls it is! There's more than one post on TT that says the shock seal heads are pretty decent actually, just not the fork seals.

[Chopperpilot]

Now I'll just need to source the reservoir bladder if I can.

[Chuck78]

You must be talking about the stock 44 mm KDX shock? They AllBalls seals are not known for being very smooth, the SKF seals are definitely superior, same with OEM.

I suppose this is a perk to going up to the modern gold standard 50mm Showa?!

Race Tech lists all these parts, look into them.

[Chuck78]

After talking to the tech guy at Diverse Spring yesterday, I got my Showa 49mm Superlight fork springs on the way, but didn't yet order any additional Superlight chrome-silicon shick springs yet,and I'm glad I didn't! For one, sadly, Diverse only makes their various part # 50mm Showa & KYB springs in one color, RED!! They often find that for Kawasaki guys , that's typically a deal breaker except a few late models with red in the OEM graphics.
What they did tip me off to is that their springs are all 245mm & tapered on the bottom to be a few millimeters smaller o.d./i.d. on the bottom end. He said all the new late model Showas use this setup. The other longer springs ir those with a different diameter at the bottom use a different torsion bushing included, which lengthens the spring as well as bringing it to the required lower seat size.

Well sure enough, all my springs which I had always just installed with the color-coded paint indicating the rate, mounted on the bottom, also our tapered in slightly at the bottom!
Looking up aftermarket springs trying to find different colors than red in a chrome silicon super light spring construction, what I found is all the companies advertised read only and their pictures actually show the diverse spring part number on the coils!

But... Teknik Motorsports out of Australia have black and white options in their house branded "Made in USA by the finest spring manufacturer" HiCalibre name brand with the less common sizes stating that they are a special order as they are stocked in the USA and shipped to Australia.
This got me looking into these a lot more, and I realize that late model Honda CRF250R shocks use a 243 mm spring, whereas the standard Showas are 250 or 260, and the 46 mm Showa 1996-1997 RM shocks which I had hoped would clear the crankcase better on the KDX application, actually come with even longer springs and that is why they weigh more or the same as the 50 mm springs, the longer springs have to have thicker coil wire stock, and also are too long for our internal lowering unfortunately, so those are deal breaker.


Where I'm going with all this is that I realize one could get the aftermarket springs for the CRF250R models that are 243 mm long, preferably in the HiCaliber or possibly Eibach brand as they advertise that their springs are also extra lightweight, but they do not advertise chrome silicon on most of them although I suspect it might be Eibach that makes the HiCalibre springs.
Using this absolute shortest spring possible, and now realizing that they have a taper on the bottoms so they are smaller outside diameter, that longer lower spring seat on the '01-'04 RM125 shocks might help get a slight bit better clearance against the KDX current case with the shock spring topped out.
I initially started brainstorming about this late last night thinking about the 2024 KX450 shocks using the same spring and having that extra tall lower spring seat that is like nothing I've seen prior, it's almost the entire height of the bump stop that is contained within it. I see now that this shock is perhaps is the # 1 best candidate in conjunction with the shortest 243 mm Honda CRF250R spec 243mm spring from HiCalibre or Eibach. With us lowering the shock internally to get 438 mm length fully extended with at least 118 mm of shaft travel, the short spring and tall lower spring seat definitely sounds the best.
I still need to do my crankcase clearancing test and see just how well my titanium spring will clear, as it doesn't really have that taper since it was another universal type aftermarket fit spring.

[KDXGarage]

Technical Touch has KYB seal head, piston, piston o-ring, special nut, bladder and bumper.

Someone clicked on a computer, and the computer didn't tell it the easy answer.

I used to sell rebuild kits and bought parts from them.

[Chopperpilot]

Technical Touch has KYB seal head, piston, piston o-ring, special nut, bladder and bumper.

Someone clicked on a computer, and the computer didn't tell it the easy answer.

I used to sell rebuild kits and bought parts from them.

Yeah, I went through their website and saw a few 14mm bushings, oil seals, etc (figured I could just rebuild the seal head). The descriptions for them listed different bikes and the oil seals had different lengths, so I wasn't going to guess. Hence my email to them describing the bikes and the 44mm KYB shocks on them. I don't want to get a part that doesn't fit, any ideas? maybe just tell them I have a 97 KLX300R?

[KDXGarage]

It is possible to rebuild the seal head. It would be just about the dumbest thing you could ever do in your life. Just buy a new one. It is VERY difficult and time consuming to get the seal body peening opened up with normal tools. If you have ever seen a video of people in India or similar place on a dirt floor and safety sandals, no eye protection, etc. beating on car parts with whatever tools they could scrounge up, then that is the point in my life I would try again on rebuilding a steel seal head.


Bladder

120104600101



Bumper

120341600101



Nut

120181200401



Piston o-ring

120224400101



Piston Ring

120214400101



Seal Head

120244400101

[Chopperpilot]

Awesome, thanks. Looked up the part #'s on their website, most are out of stock. They have the seal head, but are listing it as a 16mm. Aren't the shock's shaft size 14mm? The seal head and bumper are both listed as 16mm

[KDXGarage]

You're welcome.

[Chopperpilot]

The shock shaft is 14mm, so I think maybe the 'salesman' was correct? Or they are mislabeling their stuff?
Anyway, my plan is to build the KDX shock up with a gold valve, RT shim recommendations, RT (and KDXGarage) spring recommendations. I am also going to build a 'frakenshowa' shock. Some of this will be educated guess work because I'm using a 2005 RM shaft(18mm), spring (5.1 - 5.2? The ebay seller didn't exactly know what he had) in a 2003 DRZ body. I'm going to use the 2005 RM HSC adjuster (more holes for flowing the 18mm shaft oil) and probably a rebound separator valve. The valving will be guessing off of some threads on TT. I think the nice thing about this is that I'll have a known, 'nearly perfect', shock to ride on and judge the valving and other performance benefits of the Showa shock on.

[KDXGarage]

All the 1986+ KDX200 / KDX220R / KDX250 USA models are 14 mm. I think 1983 - 195 are also, but can't remember. I assume they all are really on back to 1980 with the KDX175 Uni-Trak. The body and piston are 44 mm on 1989 and newer.

They don't really go first by what it fits. It is not exactly customer oriented first, just for techs and tuners mainly. It is by size and not so much application.

20 years ago, I did a fair amount of buying and disassembling as you are doing now. I just kept it all lime green. It helped me to learn what was going on in these shocks.

[Chuck78]

Back on the Yamaha KYB topic.... A guy that's semi-local to me just told me some very interesting news today!
He picked up a cheap 2012 YZ250F donor chassis that he was using the forks off of for his KDX200, and was hoping to use the shock also. I'd previously looked up the approximate length of the Yamaha YZ shocks via Teknik Motorsports website listings, and they are all way too long. Well from what he says, the clevis off the KDX shock looks like it will swap directly in place of the clevis on the YZ250F shock, reducing the overall length almost to that of the KDX shock, & only about 2mm longer than the KDX shock when swapping the KDX clevis to the YZ shock!
I'm curious to see if the rebound adjuster assembly will be a perfect match still or not. If not, then that would be a pain to get to work correctly. Also curious to see how it will fit into the KDX frame as far as reservoir placement.
Edit - he said he does believe the rebound adjuster will match up perfectly

This was a very very interesting discovery especially with these new 28mm bearings or even the prospect of making a reducer in a lathe for the 30mm ID bearing (30x47x12) that AllBalls and Pyramid Parts sells...

We're making some pretty awesome discoveries lately on suspension mods for these KDX's. The stock suspension does alright for a casual trail rider once revalved & correctly sprung, but really if you push it hard or want significant weight savings, it's best upgraded to either of these YZ or Showa routes.

[Chopperpilot]

Well dang! I was disassembling the KDX shock today and trying to pull the reservoir bladder cap out I ended up cracking/breaking the schrader valve part. Anyone got an extra cap laying around? Haha. Guess a trip to ebay for a KLX shock now.......
BTW, is it a good idea to replace the bladder every time (or at least every 10 years like this probable one) if there's no issues of it breaking down?

hmm wonder if I could put a 'bolt in' schrader in place?

[Chopperpilot]

The reservoir on the YZ shock is way too long.......like the clevis is. So is he suggesting swapping the clevis onto the 16 or 18mm YZ shaft?