Alta MX Cone Valve / Trax Suspension Swap

[#76]

I weigh almost the same as you. But our bikes weigh exactly the same. You need to go stiffer.

Dampers are dampers, and springs are springs. Both have their functions. You can partially compensate for the inadequacies of one by adjusting the other, but you should not. Traxx is just a damper, it is not magical. You first have to have a proper spring rate for your bike. Then you adjust your damper for that spring and for your riding. Not the other way around.


I know what you mean. Have you cased the ground on flat landings yet? I have.

Thanks Philip.
OK, so what did you settle on in the end from your chart / would say is best for me please?...
Oh yes...i sure have, and with my wrist full of metal and Arthritis its making riding plain painful, not fun at all....this is why i am swapping it all out.
So, please let me know what you think / have settled for on your 17 MX...and i will find one here.

I was going to ask again about the front end and to also go heavier too?...again...from your chart what should i go for?.

 

[#76]

Do not forget to use proper fork spring rates either to keep your bike balanced. Altas have heavy front ends, so the front spring should be pretty stiff.

As above - Thanks.

P.S. pretty stiff will result in less comfort?...or not if its valved and set up right maybe?.

Man i hate suspension!.

 

[Philip]

OK, so what did you settle on in the end from your chart / would say is best for me please?...

For your weight and riding, I wouldn't deviate from the rates that I have in my MX suspension thread by more than 1 - 2%. More than that, and the bike will be too soft/stiff/out of balance.

I prefer the front ends that are slightly stiffer than the rear compared to the balance that most stock bikes have. So, if you cannot find the exact spring rates that I had, then you can err to be slightly stiffer in the rear, or slightly softer in the front. But I would try to keep the overall balance about the same. You can install two different fork springs if you need to go in-between the spring rates.

 

[#76]

Thanks again. Very helpful info!.

"if you cannot find the exact spring rates that I had"

You can say that again, i have looked everywhere over here for a 66-260 or near and nothing!. Can have one made but damn.

So, @querlenker did not reply back, but searching the site i found this thread The German eMXM

In said thread is this picture :



So, that's this bike :



And in that thread @Sumik said "If you want to learn about better suspension, let the Alta ones modify by Mototech and you'll feel the difference immediately".

So, after me searching all of Google what the "M" could have been on the shock bladder it's now Mototech!, so i can and just have sent a msg over to them for some more help in all this to see just what they did with their 2017 MX. I am hoping that it might be possible to use a newer "shorter" (480ishmm) shock with some way of using the newer KTM linkages that might make it work out, somehow & give much more options for spring rates than this old prehistoric one i have!

Hope to hear back from them with some more info, will post back.

 

[#76]

OK, so no reply back from @querlenker or anyone at Mototech!.

Philip, you said that the stock spring on the MX is a 62 N/mm (even tho it says above 6.3). So, on the rear spring rate on your graph above both on Var 1 and Var 2 is 6.6, is that the same as 66N/mm?, like if you wrote it as 66?, I mean am i looking for a 66-260 spring?, or a 66N/mm spring.....urrrgh...

 

[Number Six]

Contact these guys & you should be able to get the shock spring you're after ;

http://www.diverse-mfg.com

 

[Philip]

Philip, you said that the stock spring on the MX is a 62 N/mm (even tho it says above 6.3).

6.3 kg = 62 N. The conversion factor is 9.81.

So, on the rear spring rate on your graph above both on Var 1 and Var 2 is 6.6, is that the same as 66N/mm?, like if you wrote it as 66?, I mean am i looking for a 66-260 spring?, or a 66N/mm spring.....urrrgh...

6.6 kg = 65 N. You need a 65-260 spring with the WP internal diameters.

I dug up my email records and this is what I bought from Slavens Racing (back in 2018, when they had these springs):

Product	Quantity	Price
Fork Springs WP48mm 44mm x 470mm for KTM WP 4CS & WP XPlor - 5.4N/mm (pair)	1	$110.00
Shock Springs Straight Rate for Linkage KTM & Husqvarna - 65N/mm - White	1	$110.00

 

[Philip]

I think they are still there. You are welcome!

Shock Springs Straight Rate for Linkage KTM, Husqvarna, GasGas - Slavens Racing

These Shock Springs Straight Rate for Linkage KTM & Husqvarna models are cold wound on computer controlled (CNC) equipment to achieve perfect fitment/rates.

slavensracing.com

 

[#76]

OK, so an update!.

I have managed to find a very little used from new Trax rear shock (correct for the year that the older MX suspension used) and have also been lucky enough to have it custom made to the stock 490mm length the MX uses.



Had it valved and sprung and a bladder kit too, all new seals , piston , bushes , piston ring, bladder, bump stop & a new spring all rebuilt as-new. After looking at @Philip chart and the work and time he had put into trying to find the best set up, and taking into account his ability and weight we went with a 66-260 spring in the end as i am 208.9lbs now (been hitting the Gym a lot - more muscle!) so with rider kit should be about right, hopefully!.

Even had custom machined spring collars!, as the Trax shocks use a non standard size spring diameter which is obsolete and now I have fitted a standard size WP linkage spring of 63mm I/D so its more easy if I need make further changes. Many thanks to Julian for his time and help!.

Fitted it today, I was aware that to fit the Trax shock onto the bike, the mounting area on the MX frame needed some grinding to give it the room it needs, mmm....a lot of very careful grinding!. But it's all done now and very happy with the fitment and finish too.



Thankfully i did not have to worry about the clearance of the shock with the rear subframe as there was plenty of room. So, for now all done on the rear and I will have the bike all back together by the weekend. No battery in the bike atm and man does that bike bounce back sharp if you push the seat down hard - i guess that 5 stone battery really helps!.



I really hope the Alta is going to be so different to ride when i get it all sorted out and go to test!, am very excited as never had any suspension set up for myself, ever. I know its all trial and error, especially with the Alta and it's limited knowledge for tuners, well over here anyway, and it being the older Alta too. I just hope it's all going to be worth it.

Will have more to post up soon - on the front forks i have gone with. Thanks for looking if you have, can't let this site be taken over by the Varg - Alta was first!. #76.

 

[#76]

Now the rear shock is all in and done and i can relax a bit more on that, time to get on with the front suspension!, I just picked up some WP XACT PRO 7548 front Cone Valve forks, so this will be my set up now all sorted, finally!.

Need to have them serviced & sorted for my weight and riding etc, so will be sent off soon and looking forward to it all coming together.

@Philip - again would you say to go with the 0.54's or the 0.55's from your chart?, i am now 208lbs - plus kit (Gym!) and remembering what you said about shocks are shocks and springs are springs - even tho you was doing all your homework and testing on the stock Alta 4CS - still will be ok to use that data to go into the newer type CV's i now have?.

As bought :



Test fitting : Need to run shorter Allen bolts for the front caliper!.



I am getting there, i really enjoy taking this bike apart and putting back together....still have all the Track to go and sort out from the Winter lay up!, but that's for another thread section here, but I am only one man so I do my best.

#Altarules

 

[Philip]

@Philip - again would you say to go with the 0.54's or the 0.55's from your chart?,

You went with a heavier rear 66N spring than what I had, so you definitely should go with at least 5.4N/mm (0.55kg/mm) front springs.

You are in an uncharted territory with these dampers and springs. I know people have run them before on Alta's, but you are using a different tuner, so this is like an all-new suspension project that you are starting from zero. Your spring rates will be okay, so if you need to adjust the suspension it will be all damping adjustments and front/rear ride heights.