1988 Txr312 Shock

[canadaler]

The Marzocchi "Duo-Shock" on my bike works as a great spring retainer...but little else.

 

I was told this shock was the same as the Marzocchi on the Fantic 305, but it isn't. Different lengths (Fantic is longer) and different bottom mount (clevis type on the Aprilia.)

 

I can't find a Marzocchi part number for the shock so I can't search for a rebuild kit. Checked with Mike at the Tryals Shop and he has no rebuild kits or shocks in stock.

 

Anybody know where you can buy a rebuild kit for it? I have at least a couple of shops locally who can install it and charge the shock.

 

Alternatively...anybody know of a replacement shock manufacturer? I've seen some "Wilber" shocks available for the Fantic, but no listing for the Aprilia. Ohlins...others????

 

Also does anyone know if the TXR312 shock is identical to the TX311?

 

Thanks in advance.

[lineaway]

 Shocks are not as hard as people think. With that being a remote reservoir, I think it had a Schrader valve. Which makes it quite easy to release pressure and charge once you are done. Get help to take it apart. If the seal head is in reasonable good shape, all you will need is two seals and several o rings. These parts can be ordered through any hydraulic shop. Just might take a week or two. This way is much cheaper than sourcing the parts through a `kit`. Probably under 20 bucks. I did my Ohlins this way over a year ago.  Good Luck! 

[pschrauber]

I would look up the gas filling. The gas evaporates with the time probably to through the valve.

That was all I had to do to the shock of my TXR, only thing I need ow is a new bottom rubber. ...

[canadaler]

Well there is absolutely, positively NO gas in this shock because there is no accumulator bottle on the remote adjuster/reservoir.

 

There is plenty of oil residue around the bottom of the shock which indicates to me there's probably zero oil in the shock as well. I expect that if the shock did have oil it would still provide some dampening even though there is no gas pressure. I believe the gas pressure is there simply to prevent foaming of the oil under continuous load and flow.

 

I have a reservoir/bottle from a Fantic, so that can be used in a rebuild. However I'm pretty sure this shock needs more than just gas pressure.

 

Now for a tip regarding the bottom rubber on this (or any) shock. Get yourself to the nearest discount/dollar store and find a kids hard rubber ball. (Those of us who are old enough used to know them as "Superballs.") They are dense rubber that can be drilled and trimmed as required to make a rubber stopper/bumper for your shock. Drill a hole through the center of it, equal or slightly larger diameter than your shock rod. Now use a sharp knife to trim the top and bottom of the ball (at the hole) to match the overall height of your original bumper. Now use the knife again to cut a slot in one side of the ball all the way through to the hole so that you can fit it over the shock rod without having to disassemble the whole shock. Even though this new bumper has a split in it, it will not come off because when it is in use (shock completely compressed) the concave shape of the spring retainer along with the spring acting as an outer "cage" will automatically hold the ball together and prevent it from coming out of position.

 

As a matter of fact, I've found these dense balls actually provide nicer bottoming protection than the original rubber stops. I've used this trick on both twin and mono shocks and it is cheap, easy and effective.

 

I guess I've got nothing to lose in tearing this shock apart to see if I can fix it myself. As it is, the thing is junk anyhow. 

Edited August 28, 2016 by canadaler

[pschrauber]

Well very interesting your last post, so you did change the reservoir of this shock. Then you kindly have reported in your last post that the shock is leaking a lot of oil.

Pardon ... but would it not be appropriate to tell these circumstances in your first post.

Pardon again ... but to let first guess around and later on come with all details is a bit strange.

To your shock this model from Marzocchi was made without any intension for rebuilding, but as already stated the seals are replaceable.

Beside that you need some experience and the right tools, especially when it comes to the refill of oil and gas. And when the diaphragm between the oil and the gas in the reservoir is toast due of too low gas pressure you will have a hard time to get this fixed. A professional workshop can fix this (at least where I let shocks and forks to be rebuild) as they can in need remanufacture one.

To the bottom rubber I like to have one that has a sealed surface as if you cut any kind of foam in a custom shape or drill holes inside there are everywhere hallows from the the foam bubbles attracting dust, dirt, water and oil immediately. A circumstance I want to avoid, rather I don't use any bottom rubber unto I have found the matching item.

Good luck with your home made rebuild and please don't forget the saying: "The cheap guy is paying twice" ...

[canadaler]

(Comments edited to delete responses to above criticisms over the original post.)

 

I don't come out here often...now I remember why.

 

Appreciate the information you provided that there is apparently no rebuild kit available for this shock. Thanks. 

 

Edited August 28, 2016 by canadaler

[2stroke4stroke]

If you look down from your high horse Canadaler you might spot that pschrauber is not a native English speaker and that you have placed an unjustified interpretation on most of what he said.

[pschrauber]

I just wanted to be helpful in my first post in this thread. All I got from the TO as reply where corrections and an advise at least I don't want to follow as I explained in my second post on this thread. And that I di feel a bit uncomfortable when I try to be helpful and then got blamed for not knowing what in reality was up from the guy that just asked is evident and I have no problem to speak it out too.

The TO can do write state what ever he things is eligible but should in my opinion think about that WE ALL are sitting an a kind of a glad house so throwing stones is probably not the best idea. Have a nice day Sir.

[markgm1957]

@ canadler , I got a repair kit for the DuoShock on my 312 from Andre Horvath in Austria. the shock was also fitted to older mono KTMs.

http://www.enduroklassiker.at/en/shocks-and-rear-swing-arm/4457-marzocchi-monoshock-duo-reparatursatz.html

 

 

Just disassembled all and ready to reasemble. Which damping oil is recomended? 2,5 / 5 / 7,5/ 10W? or doesn't it matter?

 

Also does someone have a manual for the bike and or the shock? That would help me lots.

 

thanks

 

@ pschrauber, Grüsse aus dem Chiemgau.......

[pschrauber]

Hi Mark,

 

great resource, thank You very much.

I ordered one already!

 

I would suggest SAE 7,5 which worked well so far for all forks and shocks to me, (weight is just 70kg!). If you weight more then probably SAE 10 would be better.

Edited October 9, 2016 by pschrauber

[markgm1957]

Thanks I will try 10W then...

[canadaler]

I ended up rebuilding it myself.

 

Machined off the rolled aluminum part of the seal head which permanently held the steel retainer cap. Removed the cap, changed the seal (14 X 22 X 5) then reinstalled the cap and held it in place by drilling and tapping the outer circumference of the cap/head with three 1/2" #4 machine screws w/Loctite.

 

I used 10W oil to refill it bled the air out of the system then temporarily recharged the accumulator to 120psi. This was the limit of my compressor and is obviously not pure N, but was sufficient for test purposes. Everything worked fine with no leaks or shock fade throughout a fairly difficult trials. I'll get it charged properly at a local shop to about 140psi of N now.

 

Total cost for the seal and oil was about $25. Several hours of labour in it for me as I hadn't had one apart before. But it was simple enough to do once I figured it out. Only trick to it was getting the circlip off the rebound dampening adjuster assembly. You need to back off the rebound clicker as far as it will go to loosen the stack and provide enough clearance to get the clip out of it's retaining washer. 

 

So far so good. Now we'll see how long it lasts. As I said before it was junk as it was so it was worth trying to save for a minimal cost.

Edited October 18, 2016 by canadaler