1983 40mm forks

Sorry if this has been asked before, but what is the best seal combo to stop leaking forks ? Had mine done twice now, i run gaiters to keep the crap out but still they leak - it drives me nuts

The last time the guy did them he said the bush in the lower fork leg was badly worn and that is what is causing the problem, is this right, can you buy a replacement bushes ?

Cheers for any help.

Rathers

Yes the upper and lower bushings can wear and allow leakage
This guy has what you need:http://www.husqvarna-parts.com/page/page/3737813.htm
Use his seals, thier much better than say the " Leak Proof" brand.

Here's a look at the bushings:

The 86 forks were very easy to rebuild. So EZ in fact I didn't take many photos. Anyway, here's how it goes:

Before removing the fnt. wheel, have an assistant sit on the bike and put full body weight on the forks. Doing this, slightly loosen the bolt at the bottom of each fork leg. Just break loose.
Before lossening triple clamp bolts that hold the fork tubes, slightly loosen each fork top cap.
Remove the fork tubes from the triple clamps.
Remove the top cap, spacer ( s ), spring, and drain the oil.
Remove the dust wippers or gators.
Remove the spring clip above the fork seal. An ice pick and small screw driver work well for this. There may be corrosion to deal with here so penatrating oil and small hammer to loosen up the clips may be needed.
Remove the bolt for the bottom of the fork leg.
Grab the slider in one hand and the tube in the other and fully extend the fork repeatedly using the tube to hammer out the seal, backup washer and top bearing.
Remove the internal snap ring from the bottom of the tube and remove the bottom valve pc and metering tube.
With both thumbs expand the lower bearing and slip off the tube.
At the inside bottom of the slider there is a bottom out washer that has a radius on one side. There is also a stepped washer that is sealed to the outside bottom of the slider. Remove these.
Clean everything and chase threads at bottom of metering tubes. Steel wool packed on a 12Ga. shotgun bore brush soaked with Gunk Engine Degreaser works well to scrub out the inside of the tubes and inside of the sliders as well as the bottom of the sliders. Clean the seal area.

Get wiper boots, fork seals, upper and lower bearings, cap O rings, and top out washers from: http://www.husqvarna-parts.com/page/page/3737813.htm He sells Cagiva/MV/Husky OEM fork seals. Go to a local hydraulic seal supplier or to McMaster Carr to get 8MM fastener seals for lower bolts. McMaster #93786A150 and 6MM fastener seals for the drain screws McMaster # 93786A125. You will also need something made of hard plastic, aluminum, or brass with a 40MM id. for upper bearing and seal installation.

Reassemble: Put top out washers on metering tubes. Put metering tubes in fork tubes. Put bottom valve in fork tube and secure with snap ring. Slide lower bearing on to tube.
Put bottom out washer in slider insuring curved side is down.
Coat bearing with oil and put pre assembled fork tube in slider. Apply sealer to stepped washer and put fastener seal on bottom bolt. Screw lower bolt into metering rod and snug up to set sealant. Tighten later.
Coat the slider upper bearing bore and upper bearing with oil. Using your 40MM id tool start the bearing into the slider. Place the old bearing on top of the new bearing and using the 40MM id tool drive the new bearing all the way in. Grab the old bearing with channel locks and pull old bearing out of slider. Put the metal seal back up washer in the slider. Coat the new seal with oil and slide into possition concave side down. Use your 40MM id tool to start the seal into the slider. Place the old seal on top of the new seal and use the 40mm id tool to seat the new seal. Install the retianer ring.
Install springs and spacers. Put new O ring on top cap and snug it into fork tube. Reinstall forks and wheel. Get your assistant to comperss the forks and tighten up the bottom bolt. Install drain screws with seal washers. Check pre load of the springs and adjust spacer length to suite. Remove the top cap and put in fork oil. Reinstall top cap and tighten.

It is strongly recomended that you service the steer head bearings at this time.

Hi Guys,
I don't mean to confuse the information here or detract from it in any way; it's all very useful. But I'm pretty sure the 40 mm forks used on a 1983-85 are different internally than those used on a 1986. There are no lower bushings and some other assorted parts and there are no clips retaining the seals in the outer tube. At least that is my experience. Perhaps others can confirm.

The OP, Rathers stated his had worn bushings in his first post. The parts manuals for those years 83/86 show similar construction, but agree, and we all know there can be quite a bit of varance in these older bikes. AND, maybe not the original forks?????

Heres a parts list for an 83 that shows the forks:https://www.halls-cycles.com/Catalog...all_models.pdf

Heres a parts manual for an 86 model, similar, that shows the parts a little better: https://www.halls-cycles.com/Catalog...t_models-2.pdf

The 1986 fork lowers are cast K2 and the lowers of 84 (and other years?) is cast K1. There are external differences, i cannot remember internally, but i believe they are different as with the 1986 forks you can undo the bolt at the bottom of the fork and use the stanchion to pop the old seals out. You cannot do this with the 1984 forks.

l have a pair of 1984 forks apart, let me know if you want pics.

My forks are 83. I think the bushes referred to above are for an 86 fork (items 46 & 47 on page 4 of the 86 parts manual). Looking at my 83 manual I can't see any bushes identified, so I assume the 86 ones won't fit ?

From memory, the only bush I can remember in the forks is a bronze sintered type which was part of the lower fork leg, to be honest it didn't look like you could get it out.

Whilst I want to keep the bike as close to original as possible, it is for racing so maybe a good set of 86 forks is the way to go, at least then i stand a chance of keeping the oil in for more than 3 races.

Any other advice, greatfully accepted.

Cheers, Rathers

Hi there Northern Husky,

Could you upload some photo's of your 84 forks so I can compare to my 83 ones ?

Can you see any bushes in yours ?

Cheers, Rathers

Soory, apalling English.

I mean't bushings of course.

......................lol , sorry yesterday i got bored pillaged the seals from 86 forks and fitted the 84s to the bike ( just find i dont have a brake stay ).

Don't know if this is possible, but can you fit the later internals say 86 into 83 lower fork legs ?

I like the forks looking original, so not having disc brake mounts would be better, the rules over here in the UK not really an issue. Most of the Jap bikes have newer forks on with disc brake mounts, I just don't think they look as good.

If anyone has done this I would be grateful to hear how easy / difficult it is.

Cheers, Rathers

l tried and couldnt make it work, doesnt mean it cannot be done, its just not a straight swap, there are differences in the lower stanchions.

The early style 40 mm fork used two pressed oil seals stacked on top of each other. They are 40mm x 52mm x 8 mm. They are a rubber/steel spring loaded oil seal with a wiper lip. If your forks leak consistently (Many do) there is an easy fix available through your local bearing and seal supplier. Buy an otherwise identical metric oil seal in 39mm x 52mm x 8mm. Some run only in the top position, others run both seals in the smaller size. It works, the 39mm ID seal is only .040" in diameter smaller. If you run both positions the forks are a little tight for a day or two.
By the way, my experience with "Leak Proof" brand fork seals is that they leak very consistently in all applications, even the Pro Moly. That type of seal design is better suited to higher pressures (The pressure acts to increase the sealing force) than it sees in motorcycle fork suspensions and it doesn't seal effectively when the forks are extended and the pressure is low (IMHO)

Regards,
PC

Thanks alot for the tip, HT maybe stick this one in the tech section? I have three bikes all with new seals 40-52-8, two in each side and still weepage. Getting a set of 87 forks ready for my 84 WR250 and will try the 39-52-8 seals, Thanks again, Scott

I think the K1, K2 may be misleading. I have a set of 40mm from a WR year unknown. Stamped K2. No bottom bushing just a top bronze one. My 84 XC forks are stamped K1. Hmmn.

I don't recall seeing this thread. From my experience those things in the picture of the secont post in this thread seem to be associated with the single 10mm thick seal secured with a snap ring. I call them teflon bushings, I bought the last three Letco had a long time ago so I am short one, they cost quite a bit more now. Perhaps different models made the change at different times, my 86 ae430 still had the bronze top bushing, no lower bushing that I am aware of and two 40x52x7 seals. Strange I see a lot of 8 for the thickness here. Or maybe I don't remember too well. And it is hard to get 10 mm thick ones like origional most standard size seems 9.5 or that is what I found and just got the real 10 mm ones from the dealer network. Well not all dealers in the network sell you oem (origional equipment m????) so if you care you ask. If you don't ask you might get tucker rocky 9.5 with the tucker rocky identifying portion of the packaging cut off.

How to make them not leak, The first dealer and real local I used liked to turn the top one around. I can't say that worked real well but he went on to different things. I once had a little red container perhaps like one for face makup a short cylinder whith pop up top. It had some grease like stuff you would smear on the seals when you put them in and I think that helped.

Fran