Jump to content
Sign in to follow this  

lowering xr400 spring length?

Recommended Posts

I am going to lower the xr by 1.75 inches by puttting spacers internally to shorten travel. I bought 11.5 kg rear springs and .47 kg fronts. I am 220 dry,LOL and plan on doing shim stock mods also. Is this going to put more load on springs at resting position,thus stiffening it up too much in front? Not so worried about rear,plenty of adjustment for spring. Should i cut off inch or so of springs,or use stock ones? I know there are lots of people who say dont lower,just too hard to get on and off it at 62 years old with 28" inseam,and lots of injuries,no flexibility left. Thanks for any help guys,as always!

Share this post


Link to post
Share on other sites

Cutting the springs and making up the difference with a spacer doesn't change the length of the forks or change their distance of unladen travel. With the right spring rate, all that would do is cause more sag, making the bike sit lower in the stroke. I'm guessing this is what you mean in saying "shorten travel". To actually shorten unladen travel you'd have to cut and re-machine the length of the damper rod, then try to calculate the right spring rate and cut a spring to match.

.47 springs seems like what you'd use for your weight with the fork configured normally. Cutting them and increasing spacer length to try to get the bike to sag more to lower ride/seat height seems counter intuitive. If you're going to cut springs, try the stock springs first. You know, you can also raise the fork tubes in the triple clamps to lower ride height.

What year XR are we talking about here? You indicate you bought more than 1 rear spring.

Are you aware that you can install lowering links for the rear to bring ride/seat height down?

Share this post


Link to post
Share on other sites

heard mostly bad about lowering links,any input? Thought i would machine spacer so dampers wouldnt return full length,thought i could slide custom made spacers over dampers to lessen travel,then shorten springs similar amount.?? Only 1 rear spring,my bad!

Edited by firstplacephoto

Share this post


Link to post
Share on other sites

Oh, I see. You're going to put a spacer on the piston rod, above the piston and slide that assembly inside the damper tube. Don't guess I've ever heard of anyone doing that.

Do you plan on doing the same kind of thing to the shock?

Don't remember reading anything bad about lowering links. They're a pretty simple concept, not much to go wrong.

 

Share this post


Link to post
Share on other sites

plan on same deal on shock,believe that is how they are lowered for ice racing,maybe? Have heard the lowering links change ratio of shock linkage and not for the better. Need new oil and seals front and back anyway,so im gonna open them up and see what i can do. Bought a nitrogen fill setup,and have a tank of nitrogen for shock. Worst case scenario ill leave it stock height,and do shim stack mods recommended here at TT. Any input would be appreciated,making a couple of seal seating tools tomorrow,and have seal bullet for shock.

Share this post


Link to post
Share on other sites

Bad news,I changed seal and put 5 wt maxima shock oil in rear. Went step by step with rocky mountain atv video on shock rebuilding,didnt seem too tough. I removed shim stack,kept as set on screwdriver,and installed a spacer on shaft below seal which i made .700 thick,14mm id and probably 24mm od,so it didnt hit face of new moose seal,just hit inside metal part of it,didnt want it to keep rubbing seal. The moose seal looks a little different shape on bottom than the honda seal,so i made spacer smalled od than washer which used to bottom on original seal. Reassembled stack,peened and loctited nut,bled air,made sure oil was passing thru valve from chamber to reservoir,all looked good. Put it together with new heavier eibach spring,but didnt have correct nitrogen regulator,one i was gonna use fron welder only goes to 50,need 160 i believe. I ordered new regulator and put small amount of air pressure in reservoir to get things seated. Seemes like little dampening when in vise,but thought nitrogen would help. Put together,bike feels great  height wise,with forks raised up a similar distance in triple clamps,but its a pogo stick in rear! Turned adjuster on reservoir both ways and rebound screw on clevis both ways and didnt seem to have any effect. Will filling it with Nitrogen make a difference,or should i pull it apart now? Dont mind paying for a nitrogen fill if it will fix it,but dont want to spend 25 or 30 bucks if it wont. Regulator was supposed to be here on friday,but doesnt look like that will happen,shipped from Cal. delivery date doesnt seem right that was on auction,had high hopes of riding this weekend.

Edited by firstplacephoto
omitted info

Share this post


Link to post
Share on other sites

They say definition of insanity is to keep doing same things over and over again,and expect different results! Just took bike and shock apart again,same results! Checked if lower screw on clevis was working,seemed to move rod inside shock shaft body in and out,was a little crap in there,rinsed and blew it out a few times. bled and reassembled according to rmatv video again,but slower and waited longer for any air to come out. Seemed to have dampening in vice,but in bike its a freakin pogo! Time to pay somebody i guess,i just enjoy doing new things on bikes,and this didnt seem so difficult....Glad i took half day off to get it done,would have been way better than working if shock was ok,LOL

Share this post


Link to post
Share on other sites

If you have ANY debris in the shock body, it is contaminated. needs to be surgical clean. And sounds like there is still air to be bled out. 

Share this post


Link to post
Share on other sites

You need nitrogen to get the full effect I believe, but I am inclined to think you may also have air in the oil still as RH said.  Good excercise and don't give up. I am building a Nitorgen rig right now so I can rebuild my shock.

Share this post


Link to post
Share on other sites

I'm not familiar with this shock, but using a spacer (.7mm) on the shock shaft to reduce travel can cover the low speed rebound ports on the shaft. These ports (two holes opposite each other on the shaft near the base plate) allow fluid bleed at low rebound speeds and flow here is adjusted by your rebound clicker. A lowering spacer can cover these holes causing slower (more restrictive) rebound damping. Some use an external spacer instead between the seal head and it's retaining circlip to restrict travel.

Also. Delrin is a preferred material for the fork lowering spacers. I've seen aluminum used instead and over time the aluminum rubbed enough to develop fragments. These small particles alter damping and can create excessive internal fork wear.

Is it possible your shock piston is in upside down? This would make the larger compression ports control rebound damping leading to less rebound damping (pogo).

Also, a stiffer shock spring can cause faster rebound (pogoing) if rebound damping isn't stiffened to restrict the increased spring energy.

Most suspension tuners recommend not using lowering links for many reasons.

Just a few things to consider. Good luck!

Share this post


Link to post
Share on other sites

Also, your fork springs need to be shorter by the same length as your lowering spacers to keep preload the same. If you choose to cut your existing springs, your spring rate will be stiffer. If you don't wish to increase your spring rate you will need to buy new, shorter springs of the rate you desire.

Share this post


Link to post
Share on other sites
7 hours ago, motrock93b said:

I'm not familiar with this shock, but using a spacer (.7mm) on the shock shaft to reduce travel can cover the low speed rebound ports on the shaft. These ports (two holes opposite each other on the shaft near the base plate) allow fluid bleed at low rebound speeds and flow here is adjusted by your rebound clicker. A lowering spacer can cover these holes causing slower (more restrictive) rebound damping. Some use an external spacer instead between the seal head and it's retaining circlip to restrict travel.

Also. Delrin is a preferred material for the fork lowering spacers. I've seen aluminum used instead and over time the aluminum rubbed enough to develop fragments. These small particles alter damping and can create excessive internal fork wear.

Is it possible your shock piston is in upside down? This would make the larger compression ports control rebound damping leading to less rebound damping (pogo).

Also, a stiffer shock spring can cause faster rebound (pogoing) if rebound damping isn't stiffened to restrict the increased spring energy.

Most suspension tuners recommend not using lowering links for many reasons.

Just a few things to consider. Good luck!

Only noticed 2 holes on shaft under shim stack,not in view when stack is on rod.Put in .7" thick spacer,not .7mm which takes about 1.8" of travel away at rear wheel,lowers it same amount. I have spacer mounted right under seal head.Delrin sounds like a better idea,i have some at work,thanks! Will try it again,have been told more than once i am insane,its not news,LOL. Appreciate all the help guys,think shock on spare xr is going on tonight,and then i will play some more with the lowered shock.

Edited by firstplacephoto
  • Like 1

Share this post


Link to post
Share on other sites

I didnt remove and count,check shims. I just slid them off and directly onto a big phillips head screwdriver,then slid them back on shaft afterwards,without removing them from each other. I was afraid to mix them up!

unnamed1.jpg

Share this post


Link to post
Share on other sites
picture of shim stack on rod,and my spacer
592757044a7a0_xr4shimstackandspacer.jpg.0717cfcfcee0a9567d07a61cc7b0c1a8.jpg

That looks a lot like a Race Tech Gold Valve. Most suggested shim stacks on TT are for stock pistons. Gold Valve shim stacks will be different. Just something to be careful about.

You can pump your shock up with air to test it out. If it feels more normal, you can purge the air out and charge it with nitrogen.

Share this post


Link to post
Share on other sites

bike came from colorado set up with summers brace,frame guards,baja kit etc. Maybe he put gold valve in shock,no way to contact him,didnt mention it at time. Any idea what oil would be used with gold valve,I put 5 weight in it,maybe too light? i believe the bike has gold valves in it from previous owner. Racetech sells special lowering washers which have triangular holes and grooves cut into them. I assume its to let oil get to valve,which might explain my lack of dampening. I also dont know what weight oil they reccomend,I put 5 weight in mine. Its still apart,will call race tech tomorrow,fingers crossed. Thanks motrock93b  for pointing it out!!!

SPLS.shaftS_TX2.jpg

SPLS14S_220_tx.jpg

Edited by firstplacephoto
new info
  • Like 1

Share this post


Link to post
Share on other sites

My pleasure. I wonder if your forks may also have gold valves. Either way, I would suspect fork valving may not be stock.

Race tech is a good option for spacers, shims, shortened springs, fluids, and most importantly tech info. I'd try to get shim valving charts from them.

Good job getting so deeply involved in this project!

Share this post


Link to post
Share on other sites

I suspect forks will have them also,I have new eibach springs and new seals,expected that to be done by last weekend,the ss xr minnow is not getting done as quickly as i expected,LOL will call racetech today,as another forum member showed me pic of gold valve kit with plastic shim band which looks to go around the gold valve over oring,it wasnt in there,not more confused,just new confusion. 2 steps forward,1 back!

 

8802113.jpg.627b25cc4bb6f4b7b332a800a14ab481.jpg

Share this post


Link to post
Share on other sites

2 new piston bands and set of lowering washers ordered from race tech,were very helpful on phone,no rush or issues,nice to deal with brad in tech/sales. Sending me other instructions by email also! Ill keep up post and hopefully it will improve,missing parts never help,LOL Ill never understand how i rode it,but bumper on top of shock was shot,maybe it was taking the beating,new one on way also. Time to strip shock from other xr4 so i can ride this weekend. Wont be lowered,but nothing new there.

  • Like 1

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×
×
  • Create New...