Thread: Koni damper issues

Bill The only thing I can think of looking at the internal drawings for those shocks is that there may be some sort of impurity in the oil (scale from the body)allowing a partial restriction of the relief port or hindering the operation of the valve.Of course all the normal things you would already have checked no doubt,like shock body damage etc.Hopefully it is one of the rebuildable 88 series,as I not that not every one is rebuildable in this series.

Wayne

Originally Posted by wagoo

"Koni adjustable 14'' stroke model 88 1339Truck and bus series dampers being virtually hydraulically seized".
Wagoo.

............here is the problem, your vehicle is neither a truck or a bus....hence they went on a hydraulic stike as mandated by the suspension union for contracting work not in their field.

hi Bill

Originally Posted by LowRanger

Bill The only thing I can think of looking at the internal drawings for those shocks is that there may be some sort of impurity in the oil (scale from the body)allowing a partial restriction of the relief port or hindering the operation of the valve.Of course all the normal things you would already have checked no doubt,like shock body damage etc.Hopefully it is one of the rebuildable 88 series,as I not that not every one is rebuildable in this series.

Wayne

Thanks Wayne, They were sold to me as rebuildable and they do have what appears to be a screw in retainer with two holes for what probably is a special spanner in the top of the main body.The body appears to be dent free and the shaft is straight.Do your drawings show these as mono tube or twin tube construction?
My experience with Konis hasn't really been a positive one.A set of gas ones on a previous vehicle only lasted 6 months, and I had another new straight oil one the same as I run now fail in the workshop while I was cycling the suspension on a hybrid I was building. I'm starting to think the koni name is a bit overated.
Wagoo.

Originally Posted by uninformed

............here is the problem, your vehicle is neither a truck or a bus....hence they went on a hydraulic stike as mandated by the suspension union for contracting work not in their field.

hi Bill

Hi Serg,but you are wrong. It was the family 'Bus' once.

Well it was for about three days, until the wife read me the riot act and demanded I get a proper family bus or make alternative sleeping arrangements.
Wagoo.

Originally Posted by uninformed

............here is the problem, your vehicle is neither a truck or a bus....hence they went on a hydraulic stike as mandated by the suspension union for contracting work not in their field.

hi Bill

ahh, but as a derivative of the 11 seat "Omnibus" model, the strike would be ruled illegal.....

Bill, pm Rick, he knows a lot about these shocks....not sure if he is here to much at the moment, he's be busy filing chains

Originally Posted by uninformed

Bill, pm Rick, he knows a lot about these shocks....not sure if he is here to much at the moment, he's be busy filing chains

ringadingding

Bill, you can make a tool to open the top cap, I've used some RHS and welded some pin punches in the past, and broken them eventually.
Actually still have it, just have to fix the tool to re-use it.

I asked Jeff at Proven Products about breaking the tools and he said they make their own and break them all the time too.

Anyway, a Koni 88 Series is really straight forward.
It's a twin tube damper and FWIW the adjustment only preloads the rebound shim and closes off some orifices for the rebound circuit, (affecting low and high speed circuits) it doesn't affect the bump circuit at all.

I'm not sure what happened with yours other than guessing some crap has blocked the foot valve (bump valve) and hydraulically locked it, Unlikely, but it's the only thing I can think of ?

Have they gone full bump (compression) at all ?

That'll stuff the foot valve as the rebound adjuster crashes into it and bits of valve go everywhere, that may have caused it ?
If so, you'll need a new foot valve as they are flowed as an assembly, although I re-valve them.
When they go metal to metal the pressure tube/working tube also cops a beating and usually bulges, but the work around is to just flip the tube so the bottom of the tube becomes the top.
Oh, and a new rebound adjuster is necessary too.

If you want to open them up, give Jeff at Proven's a call and order some top cap o rings, piston bands and shaft seals (I'd do them as an axle set) and ask exactly how much oil for each damper.
You'll have to quote the model # to get the correct bits.

I'd use Silkolene Pro RSF 5wt shock absorber fluid.
It's the right viscosity (I've done a rudimentary test against some fresh Koni fluid, timing how fast it's flow through a syringe at various temps) and will work much better at elevated temps than the Koni stuff, it has a much higher viscosity index.

Thanks Rick, that is great information.I just realised that the bump stop rubber on that damper had fallen off somehow, but that appears to be working fine now, but I discovered when I went to adjust the damping on the other side, that damper has got air in it and is inneffective for the first 50mm of suspension up travel when in the fitted position.I'm not able to bleed it out and there is no evidence of fluid leakage It appears to work ok by hand at a longer extension though Anyway i've got a shorter 12'' stroke version I can borrow from another truck while I play around with the faulty one.
Would the screw in cap be loctited in ? and if so maybe a little heat from a butane torch would break the bond?
Wagoo.