• Husqvarna Motorcycles Made In Sweden - About 1988 and older

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Shortening WR400 -84 forks

Krudd

Krudd

Husqvarna
AA Class
Hi! I'd appreciate some advice on how to shorten a pair of 40mm WR400 -84 forks. I'm trying to make the length suit my 1981 WR240.

I've read here that it's possible to use, for example, a 4T valve spring or a piece of pvc-pipe under the damper rod and that will shorten the fork. But I don't know if it ok that the spring or pipe rests against the bottom of the top out washer as the blue arrow points at?
Or should it stop against the "shoulder" as the red arrow points?

I've got a spring that just barely fits over the "shoulder". Is it ok to grind the shoulder down a bit so I get a mm or two in clearance?
Damper rod WR400.JPG
 
Can you swap the damper rod out of the '81 forks? Because of the springless setup on the Husky fork, adding a spring does not work very well.
 
The stock forks on the '81 are 35 mm and the '84 WR400 forks are 40 mm, so the damper rods are different diameter I guess.

I've seen comments about adding a topout spring from later Husky EVO-forks to stop the fork clunking at top out,
but I'm not sure that applies to the '84 40 mm fork!?
I could get a pair of shorter damper rods from a pre-84 WR but figured I could fix two "problems" at the same time.:D
Any ideas or comments are welcome! :)
 
How long do you need them to be? The '82 WR forks have the same travel as the '84 which is 10.6" but I think the '81s with the 35mm forks were 9.8". It might actually be easier to use the '84 forks and have the spacers removed from the '81 shocks to balance it out.
 
Yes thanks, that could be a good option. I measured the forks from top to centre of axle and the difference was about 40 mm so something has to be done to get the balance back.
 
I've seen comments about adding a topout spring from later Husky EVO-forks to stop the fork clunking at top out,
but I'm not sure that applies to the '84 40 mm fork!?

The clunking is from bad top out washers ( the black ring in your picture) & yes that's a common problem on 40mm
forks.

Husky John
 
I would not even bother reducing the travel in the 84 WR forks as by the time you set up the suspension with an appropriate amount of static and rider weight sag, you will have used up at least an inch of travel.

I have both 35mm and 40mm damping rods in my basement workshop and it appears the OD of the 35 & 40mm tubes are identical for what it is worth.
 
Not sure if this helps or not, You say you need to make the length suit the 81 wr . (length or travel)
I put 84 wr forks on my 79 wr and just slid the forks up in the triples. Max stick out length is 1 and 3/4 inch any more and your tire will bottom in the fender.
 

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84scrambler said:
Not sure if this helps or not, You say you need to make the length suit the 81 wr . (length or travel)
I put 84 wr forks on my 79 wr and just slid the forks up in the triples. Max stick out length is 1 and 3/4 inch any more and your tire will bottom in the fender.
Click to expand...


Thanks, it helps. It's the length, I'm trying to balance with the 410 mm shocks so the bike doesn't look like a chopper!
But I guess I'll need to get the bike back on wheels first and try the '84 forks on before I can decide what action to take really.

jimspac said:
I would not even bother reducing the travel in the 84 WR forks as by the time you set up the suspension with an appropriate amount of static and rider weight sag, you will have used up at least an inch of travel.

I have both 35mm and 40mm damping rods in my basement workshop and it appears the OD of the 35 & 40mm tubes are identical for what it is worth.
Click to expand...


Thanks, good info. I'll need to have another look at the 35 forks I got then!
 
Answering my own question here..
I was at Arne Kring's shop the other day and he said it is possible to use a spring to shorten the stroke but it will need to stop against the shoulder at the red arrow. And also the damping would be affected of course, as the slight taper under that shoulder would be put out of play.
Damper rod WR400a.jpg

The 35 and 40 mm damping spindles are different but he had short (270 mm) ones to sell me so now the 40 mm fork I put together for my '81 WR240 has the same length as the original 35 mm one. :)
(And I got the frame etc. back from the paint shop yesterday so now I can carry on the rebuild :D )
 
Bigbill said:
Just let them sit above the triple clamp. I've seen them 2"& 3" above the clamp.
Click to expand...
3 inches can be very dangerous, have to be careful upon hard bottoming the tire doesnt stick in the fender, causing the wheel to lock up. real bad news at speed. a good check is to remove springs, let bike sag, and see if tire touches fender. can send you over the bars landing off a jump or an unexpected obstacle.
 
justintendo said:
3 inches can be very dangerous, have to be careful upon hard bottoming the tire doesnt stick in the fender, causing the wheel to lock up. real bad news at speed. a good check is to remove springs, let bike sag, and see if tire touches fender. can send you over the bars landing off a jump or an unexpected obstacle.
Click to expand...

This is how it should be done, this gives you maximum drop without the tire hitting the fender at bottom.
 
Sounds like you did the best thing, bought shorter spindles from someone who knew how to set them up. I imagine even these simple forks are designed to ride in a certain portion of the stroke for the most part.

As to sticking the tubes up it is pretty much impossible on the later clamps without the rubber dampening as the bars are in the way. I just had some springs out and the forks compressed to add oil last week didn't pay much attention to where the tire was but doubt it could have been 2 or three inches more.
 
Thanks for all input! Yes doing it this way won't interfer with how it was designed to work at least.
And I will definetly remove springs when I've got the chassis together to make sure I won't be doing any somersaults over the 'bars..
Hopefully it will soon be on wheels! Also have a TLS front brake, but need to re-lace that wheel first..
81WR240.jpg
 
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