O/T rebuilding older dirtbike shock- What's involved?

The rear shock on my 1985 XR350R is no longer doing it's job. It's an oddball one year only design remote reservoir Showa.

The bike's in nice shape. Really a time capsule from 1985. I would prefer to keep the original shock if possible.

I've spoken with two somewhat local guys that were recommended as rebuilding dirtbike shocks and while one sounded like he knew his stuff and could do it, he has turned out to be a complete flake.

Makes me a bit gun shy to ship it somewhere. I'm heavily leaning towards learning and buying whatever it takes to do the job myself at this point.

Since my shock is still in my bike and you can't see much of it, here's an Ebay listing for the exact shock so you can see what it looks like- 1985 HONDA XR350R XR 350R XR350 REAR SHOCK SUSPENSION SPRING RESERVOIR | eBay

Has anyone been into one of these before? Are there any USA resources for quality seals and internals for these old shocks or is it best to just take the parts down to my local seal house?

If I find the housing is worn or scored inside can I bore/hone it oversize, sleeve it?? Should I consider having the housing hard anodized while apart?

I appreciate any advice.

I don't know.

I've always considered shocks to be a nightmare of un-fixability due to their fine finished bores, odd sizes, pressed parts, and one-way assembly methods.

I am sure some higher end shocks can be taken apart and reassembled, however.

In the case of a 35 year old Japanese shock, I'd expect the seals to be not only metric but also 'proprietary' Honda pieces. That might limit your availability pretty severely, especially here in the USA. But maybe they are common with other shocks.

Most guys who have rebuilt shocks/forks that I personally know end up with a leaky shock/fork before long. That's because you can replace the seals but the bores usually have scoring that is a 'death sentence'.

I'd try to fix it but I'd also look into a backup plan that involves a good, new, aftermarket shock.

I don't know a whole lot about these either but always wanted to take one apart and see exactly how it works. After my back got fugged up I didn't ride dirt bikes anymore so never did get roundtuit. If you end up delving into it I sure would like to follow along if you post some pics and such as you go.

GregSY said:

I don't know.

I've always considered shocks to be a nightmare of un-fixability due to their fine finished bores, odd sizes, pressed parts, and one-way assembly methods.

I am sure some higher end shocks can be taken apart and reassembled, however.

In the case of a 35 year old Japanese shock, I'd expect the seals to be not only metric but also 'proprietary' Honda pieces. That might limit your availability pretty severely, especially here in the USA. But maybe they are common with other shocks.

Most guys who have rebuilt shocks/forks that I personally know end up with a leaky shock/fork before long. That's because you can replace the seals but the bores usually have scoring that is a 'death sentence'.

I'd try to fix it but I'd also look into a backup plan that involves a good, new, aftermarket shock.

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The one guy that sounded experienced, but flaked out said the housing bore is likely scored if it was rode low on oil. He also said that the OE seals were much better than the aftermarket stuff so you end up with a piece of shit if you don't source the right parts.

So I guess that's the million dollar question- Where do I get seals?

Here's a company in Australia that has a wide selection- Genuine Showa Suspension Parts | Teknik Motorsport

Not finding anything in the USA so far.

everything is repairable

aint no magic in a shock

tear it apart and figure it out

seals are machined

chrome is an option same as anodize

obviously cheaper to purchase

Never had one apart but memory's clicking - aren't they inert gas pressurised? …..something to do with inert gas to help damping and stop ''dieseling'' ……..ISTR in the very early days of such systems (early 70's) some prototypes etc literally blew up when they got hot ……...if they are how do you re-pressurise them yourself.

I've heard that with the pressure getting them apart can be ''fun ''

Personally I'd keep the original on the shelf and replace it with a decent modern shock unit, ….which will probably work out a lot cheaper.

Yes I know it's a challenge etc etc - but I can see a lot of work and aggro - only to end up in the scrap bin.

Usually they are pressurized with nitrogen. Pretty easy to get in a bottle and they just have a Schrader valve so no problem to fill.

The problem is all modern shocks have the reservoir integral with the shock body. They won't clear the frame or the airbox or the carb, etc, etc on my bike.

Worx will build me a custom with remote reservoir for around $800.

Eight hundred fucking dollars for a bike that's worth $1500 as long as I keep the plastics pristine. I choke on spending $250 for a set of 4 shocks for my truck, but I can't ride the bike without the shock.

I have assembled several race engines, a hundred of diesel engines, several hundreds of transmissions and a few dozen diesel injection pumps. I've had a couple automatic transmissions kick my ass around pretty good, but I got it done eventually. I can't see a shock being so damn difficult, but I don't know anyone who's ever been inside one. My riding buddies just buy cheap replacements for their CRF's on Ebay and done.

I guess my frustration is I can't find anyone who has been in these things. They're designed to be repairable. Figured I'd post here and see if anyone has been there and done that.

Garwood said:

<SNIP> ....They're designed to be repairable. Figured I'd post here and see if anyone has been there and done that.

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OEM shocks not so much. Often they weren't that great even out of the crate. Fox, Ohlins, Penske etc certainaly were designed to be serviceable. You might get on some dirtbike forums and start asking your questions. At very least you might get pointed to some decent suspension service outfits.

I always sent mine out as their are a host of specialized tools and knowledge I just didn't have.

The problem is not your skills....it's an issue of the parts being 'onerous' to work with and/or impossible to get.

A lot of stuff that's crimped together or friction welded etc. becomes very, very tough to rework due to limitations of space. They leave no room for alternate methods of assembly.

The fact yours is worn out is scary....that implies a lot of cycling and hard-to-fix wear. Hopefully it's just the seals got old and cracked apart. In my experience, the Japanese have some of the worst rubber/plastic parts.

Few people fix anything anymore and it's only getting worse.

so....take it apart with lots of digital pics so you can put it back together.

The only 'unrepairable' shock I've rebuilt was for a Yamaha Banshee. The rod gland was captured by opposed circlips, you basically had to hack at the gland until you could remove the outer clip.

Anyhoooo, post some pics of the unit? Detail shots of the rod gland and fill port on the reservoir are what we need to see, they're probably your only points of entry.

Last thing, short of a manual or documentation of a rebuild determining proper oil volume and pressure will be a headache. Not hard, just trial and error.

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Cole2534 said:

The only 'unrepairable' shock I've rebuilt was for a Yamaha Banshee. The rod gland was captured by opposed circlips, you basically had to hack at the gland until you could remove the outer clip.

Anyhoooo, post some pics of the unit? Detail shots of the rod gland and fill port on the reservoir are what we need to see, they're probably your only points of entry.

Last thing, short of a manual or documentation of a rebuild determining proper oil volume and pressure will be a headache. Not hard, just trial and error.

Sent from my SM-G930R4 using Tapatalk

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I ordered an original 1985 manual for my bike. Hopefully it will have that info. I figured when I get the manual next week I will disassemble and see what the body bore looks like inside.

I sent a PM with my phone, I have done these before.

If you want to talk to someone who wont bullshit you - you might try these guys - best to call, they get a million e-mails a month.

BBR Motorsports, Inc - Contact

I have known these guys for going on 40 years - I remember the first frame they welded together when they were still in Junior High School - I told them they were crazy to think they could make a living playing around with thumpers. I have two 1988 XR 250's that are also time capsules and the front shocks were rebuilt a few years ago with no difficulty by one of my employees who used to work for a Honda dealer back in the early 90's as a mechanic.

I realize that front shocks are a different animal . . . the rear shocks on my bikes also have the separate reservoir.

eko said:

I sent a PM with my phone, I have done these before.

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I didn't get a PM from you.

Can't hurt to take it apart,,, ,make sure it is depressurized and you need to have the stuff to repressurize it.
The "nut guy" maybe not that far off on concerns.
What is available as a "replacement" shock of a maybe slight different design? Would this be a workable option?

Sleeving a worn is very fussy work and sometimes not much stock on that bore to work with.
I used to play with valving ports and oils for different tracks so I'd have a bunch "handmade hobby stuff" and swap around.
Much,,much guess and check, the big guys have "shock dynos" for tuning even back in the days with two shocks on the back end.
A US source for a lot of seals, bands and such is :https://herculesus.com/
The oil weight used to refill makes a HUGE difference as does the pressure within 1 PSI.

I am all in favor of rip it apart, inspect and try. It does not work now, there is no downside other than time spent and few dollars.
The big part of any fix is is always inspect, why did it fail?
A really good builder will also ask rider weight, use and riding style and recommend a spring. This is the insane expensive world. Doubt you need that.
Bob

I had an 85 XL350R ,the DP street legal model.That was the duel carb,duel exhaust model.I wanted to find an XR and do a little finagling and use my tag on it.
It was one of the best DP's at the time and I doubt that there is any thing a whole lot better now.
When I was riding dirt bikes I used to subscribe to Dirt Bike mag and there were more than a few rebuilders listed.I think Fox at one time rebuilt other makes.

My son is into mountain bikes and he has the stuff to recharge his shocks,i don't think it was very expensive.

The reservoir may be a problem.Some were sealed units.Some had a floating piston others had a bladder.
Just about all of the dirt only bikes of that time had high quality rebuildable shocks.It's BS that the oe shocks were inferior , the tuning is the big difference.The DP's usually had steel throw aways.

ratbldr427 said:

I had an 85 XL350R ,the DP street legal model.That was the duel carb,duel exhaust model.I wanted to find an XR and do a little finagling and use my tag on it.
It was one of the best DP's at the time and I doubt that there is any thing a whole lot better now.
When I was riding dirt bikes I used to subscribe to Dirt Bike mag and there were more than a few rebuilders listed.I think Fox at one time rebuilt other makes.

My son is into mountain bikes and he has the stuff to recharge his shocks,i don't think it was very expensive.

The reservoir may be a problem.Some were sealed units.Some had a floating piston others had a bladder.
Just about all of the dirt only bikes of that time had high quality rebuildable shocks.It's BS that the oe shocks were inferior , the tuning is the big difference.The DP's usually had steel throw aways.

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Funny, there was a guy with an ad on craigslist parting out an 85 XR350. Said it had a good rear shock. So I drive an hour and a half to go buy it. Get there and the bike doesn't look right. It was an XL. I never thought to make sure it was an XR.

I believe the XR500 was just about the exact same thing as the XR350 year for year. So an 85 XR500 shock would probably be identical. There's a good '88 XR500 shock on Ebay for $85, but it's totally different.

OK, I just logged onto the general forum tonight to ask some DRO install and calibration questions, but stumbled onto this thread first. I run a small motorcycle business that is about 95% dedicated to suspension. Shocks and forks are pretty much all I do and making tools and spacers for them is why I have a mill and lathe. I'm still newish and machining, but am glad, for once, to be able to answer something.

This isn't that hard, if you know where to look. As one person mentioned, about the only truly hard ones are a few old Yamahas and KYBs with double-circliped seal heads. They are a borderline nightmare, and once in a while I get talked into fixing one that some other shock has already jacked up. Not always doable. Did one last month that had that setup, and fortunately had aluminum body-tube and seal-head. I used the old alum trick (same as used for dissolving taps) to etch away the out snap ring. I need to refine the process to make it more efficient, but I imagine this is what I'll do in the future.

But I digress.

I see two issues before you.

1) You want a seal source, That'a easy. Many sealheads are rebuildable and the seals for them can be had in the U.S. from RaceTech. Ones and twos-ies easiest to just get from Ebay. Or if you get stuck, message me and I'll get you one. The parts you need will NOT be in your manual most likely, but as it's a Honda, it is probably a Showa seal. You just need I.D. / O.D. and thickness, and it needs to be the same type (soft/pliable, or with a metal or polymer cage -- most are the former for the internal oil seal, and the latter for the external dust seal. Some of the seals that have a 24mm I.D. are about impossible to find, but you can just bore the pocket to 26mm (or 25.95) and put in a more common 26mm O.D. seal. Honda and Showa are about as easy as you get. Just not well documented, so you often have to rip in, see what's thhere, and then as a consumer, order it.

The second part is harder. if the bore is scored because it ran low on oil too long, you are semi-screwed. There is no economical way to replate the inside that I am aware of, and I have >20 years doing this. That having been said, jsut like car motors, they wear a bit barrel shaped, and compared to a shock low on oil, a rebuild can still bring up from useless to anywhere from 50-80% effective. Worth a shot.

If yours is really worn, you can grab a donor off ebay. Obviously no guarantee it's not bad too but I do it pretty often for customers and it's good may 4 of 5 times.

You also need to figure out your shock architecture. Someone above (wrongly) mentioned that all modern shocks have built in reservoirs. That's only 1 of the 4 basic types. I touch all 4 pretty much every day. You can have 1) Emulsion (no reservoir and no separation of oil and gas -- some are pressuized and some are atmospheric) 2) Integrated reservoir (oil and gas separated by a floating piston in most cases). 3) A piggy back external reservoir (oil and gas separated by piston or bladder 4) A remote reservoir on a hose, but otherwise the same.

You need to figure out which you have too, or you won't know how to fill and charge.

Lastly, if the sealhead can't be rebuilt, RaceTech can often provide full sealheads (again, Ebay is probably best). They too are simple and though marked as a brand, not really brand specific. ID (shaft OD). OD (tube ID) and thickness/height (othewise you'll change the stroke and OAL of the shock.

Hope that helps.
Now back to DRO mysteries.

I have an '83 XR200R that I've basically been all the way through, except the shocks. So I'm very interested in this topic. I've found good help here;

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