Problem with FOX shocks

[netarch Member Find all posts View Profile Close netarch]

Well had a nice drive through Toolangi on Saturday nothing to difficult on the day just a pretty good drive. We started with Rocky track, Downies spur, RPC620, Luke creek, Lyndels track, Aeroplane track, so a good range of tracks and conditions. Anyway after the drive thought that the car was bouncing a little more than normal but thought it was normal as after a day in the bush as it always takes a while to get use to roads again. So got home didn't think anything more about it until I washed the car this afternoon. It was at that point I notices the reservoir on the fox shock was adrift and on further inspection there was no shock connected to the chassis. Anyway what are your thoughts on what would make this happen? The springs are the same as I was using with my old OME shocks they lasted 4 years the fox shocks only 4-5 months.

What they looked like before.



What they look like now

[Whitey Shockie Maker of the Month Award Find all posts View Profile Close Whitey]

Hey,

Can you tell us what the closed-open lengths of your rear shock are and what free length your rear coils are?

It looks like something (stick etc.) has become trapped in between the chassis and the reservoir hose and forced it apart. Must have been strong to snap the shaft!

Very unlucky, but at least you didn't lose the shock and can get it rebuilt.

Best

Mark

[seenthelight Junior Member Find all posts View Profile Close seenthelight]

Looks like the shock was only holding on by about 1/4 of the pin....
3/4 of the pin is rusty and 1/4 grey,(the grey is what was holding the pin to the shock)
when the pin let go the reservoir hose tore out
If it was mine I would return it and see what they say
Cheers
Geoff

[netarch Member Find all posts View Profile Close netarch]

Unfortunately I didn't measure them when I had them off but they were about 4cm longer than the ome ones they replaced. Below is a picture of them side by side with the OME ones they replaced.

I am pretty sure that the shock broke and the reservoir line broke after as it cannot reach to where the shock is currently sitting. It also had a sharp bend towards the current shock location when I first looked at it.

[netarch Member Find all posts View Profile Close netarch]

Looks like the shock was only holding on by about 1/4 of the pin....
3/4 of the pin is rusty and 1/4 grey,(the grey is what was holding the pin to the shock)
when the pin let go the reservoir hose tore out
If it was mine I would return it and see what they say
Cheers
Geoff

Definitely going to talk to the guys there about it. I cant confirm the rust I havent taken them off yet. I think that what you are seeing is more dirt in the top of the shock than anything else. The thread on whats left of the shock connected to the chassis looks pretty clean though (on the part of it I can see) the lower parts look to have some metal fragments in the thread from being pulled out of the top of the shock. I just sprayed a little more water on it and have posted some cleaner photos below. There is definitely damage to the top of the shock as can be seen below.

[photoprado Avid PP Poster! Find all posts View Profile Close photoprado]

Hmm. This is curious.

So the top mount is a threaded stud into the top of the shock, not a welded top mount?

[kevdebbi Senior Member Find all posts View Profile Close kevdebbi]

Unfortunately I didn't measure them when I had them off but they were about 4cm longer than the ome ones they replaced. Below is a picture of them side by side with the OME ones they replaced.

I am pretty sure that the shock broke and the reservoir line broke after as it cannot reach to where the shock is currently sitting. It also had a sharp bend towards the current shock location when I first looked at it.

40mm longer sounds like a lot longer, how much longer than standard do you think they are when fully closed? It looks like the bump stops are still the standard length so maybe the longer shocks are bottoming out before the bump stop? This would cause a huge load to be transferred directly to the shock and mount. So the top mount is just screwed into the top of the shock? Doesn't sound very strong. Like the others said definitely get on to the supplier and see what they say. I hope they can sort it out quickly for you.

[Razorback81 Advanced Member Find all posts View Profile Close Razorback81]

that would happen when full droop is at it's most extreme
as the shock is what is the limiting factor
the weight of the diff wheel & the HD spring trying to throw it's self away from the car every time the wheel leaves the ground

i see this regularly on race cars with no limit straps

with the threaded section on top , each cycle up & down wants to make the shock try to turn slightly so if there wasn't enough lock tight when installed the constant shock over corrugations could have made it loose and then slowly unwound to where it has been pulled out of the last few threads


where did you get them from ?
from a local supplier or did you buy them direct?

i might be able to source the parts to repair it ( and rebuild it for you ) as i am a shock specialist for both King Shocks & Fox shock

did it bent the shaft?
looking at it it would require 1 x body + 1 x hose, plus oil & assembly

James

[netarch Member Find all posts View Profile Close netarch]

Yes 40 is probably to much I was going on the picture I think I added 2 rubber pieces when it is only one bigger. They were the ones recommended for a 150 prado with 2 inch lift.

Looking around on the web quickly I found these measurements

Extended 24.80 in (629mm) .; Collapsed 15.20 in.(386mm); Stroke 9.60 in.(243);

So a bit longer than other 150 shocks when collapsed

[Razorback81 Advanced Member Find all posts View Profile Close Razorback81]

can you have a look at the other shock to see if it has any damage to the diff side of the shock body

as they are a 2.5" body when fully compress (if you can before the bump rubber stops the up travel) as to whether the body touches the diff and puts extra pressure on the top pin

i just had to go and check my Kings to see how their top pin is installed and it is welded in

James

[netarch Member Find all posts View Profile Close netarch]

All sounds pretty reasonable I was thinking the same that they pulled apart on full droop but when installing them I still had to compress them with the axel hanging with no support. I definitely didnt touch the top section of the shock.

I got them from transamerican wholesale on my last trip to the states in Jan. I will get onto the guys there and see what they say. But from what you are saying if it works free they wont be saying its a problem with the build of the shock.

I may take you up on the fix option, pm me your number and we can talk about it. Whatever happens I need a better replacement before mid june as we are off to the cape. In the mean time the old ome ones are going back on, but thats a job for next weekend.

[Razorback81 Advanced Member Find all posts View Profile Close Razorback81]

PM sent

if i get them from you in time i should be able to turn them around and send them back to you the same day i build it
getting the parts will pose the problem

you can call them till Tuesday morning (or real late Monday night)
then its a week to get them once they have the correct part ( if they don't have to make it !!)

if you wanted any valving changes that is a good time to do that as they have to come apart completely to fix it

so we should need
1 x pin top
1 x body
1 x seal kit
1 x hose
i have the oil in stock

is there any other damage ?? seal hosing ? shaft?

James

[Whitey Shockie Maker of the Month Award Find all posts View Profile Close Whitey]

with the threaded section on top , each cycle up & down wants to make the shock try to turn slightly so if there wasn't enough lock tight when installed the constant shock over corrugations could have made it loose and then slowly unwound to where it has been pulled out of the last few threads

Hey,

This is definitely the cause.

After speaking with John at Zordos today, he mentioned he has seen this type of problem numerous times, particularly on Bilsteins with top pin adaptors in 100 series landcruisers.

The problem really lies with the design concept, a "standard" shock body that can be used in multiple vehicles simply by changing the top pin adaptor.

Many installers will use small tack welds to prevent this unscrewing occurring. Even a lot of loctite can sometimes not be enough to prevent the top pin unscrewing.

Apparently Icons are the same as Fox, but King is welded?

Hope this helps netarch get on top of this problem!

Best

Mark

[sunny120 Junior Member Find all posts View Profile Close sunny120]

Don't make sense. Unless the piston rod doesn't twist/turn independently from the shock body (welded together) I can't see why on a compression or rebound stroke of the shock would want to twist the top mounting pin off. The body is secured to the chassis and should not move, any twisting motion I would assume would be taken up by the piston rod as that is a moveable part of the shock.

[Whitey Shockie Maker of the Month Award Find all posts View Profile Close Whitey]

Don't make sense. Unless the piston rod doesn't twist/turn independently from the shock body (welded together) I can't see why on a compression or rebound stroke of the shock would want to twist the top mounting pin off. The body is secured to the chassis and should not move, any twisting motion I would assume would be taken up by the piston rod as that is a moveable part of the shock.

Hey,

The shaft in this case can't twist around as it's connected to the ring eye at the bottom pin.

It looks from the photos that only a very light dab of loctite was used in the top pin adaptor thread...not enough.

Also keep in mind that the rear axle is also experiencing twisting motions (as it's a solid axle) as one side goes up and the other goes down, it is following an arc.

With small repetitive twists like this, I think the piston seal is gripping on the inside of the shock body and transmitting the twisting forces experienced by the diff, eventually twisting the shock enough that it unthreads from the top pin adaptor.

This is apparently quite common with this design of shock, and a couple of small tack welds on the top pin adaptor is typically used to prevent this happening.

Best

Mark