How do you tell if shockies are worn?

[twr7cx]

This afternoon I replaced the front and rear shock absorbers on a mates Discovery 1 for him. His old ones were shagged, could tell when driving and once removed and depressed 20 minutes later they still hadn't pushed themselves back out - vehicle had done 280,000kms and they looked like the original ones. New units are Repco Maxitracks and made a huge difference!

But this got me wondering. How do you tell when they are just worn/aged, but not completely shagged? For example my vehicle is a 2003 Discovery 2 HSE with the ACE system. The suspension is raised 2", but I'm not sure that the shock absorbers were replaced when this was done, which means they may have 180,000kms on them already (although they look reasonable clean and unmarked). Is there a method to testing them?

[rick130]

If they were original they wouldn't "20 minutes later they still hadn't pushed themselves back out" as they aren't gas pressurised ;)

The OE D1/Defender dampers were twin tube hydraulic without any gas pressurisation.

In a gas pressurised damper the gas doesn't provide any damping, all damping on a modern damper is hydraulic, so even if a twin tube gas pressurised damper loses it's nitrogen it can still work effectively if it hasn't lost any oil or isn't worn or broken internally.

A mono tube damper such as a Bilstein won't work adequately if it loses it's gas charge, but it's highly likely it's lost it's hydraulic fluid as well.
It's just the way they are designed/built.

For the average punter checking shock absorbers/dampers is nigh on impossible, even experienced race car drivers can't often pick a dying shock.
The only surefire way is to remove a damper and dyno it.
Mostly you replace on mileage/time unless you are experienced at setting up suspensions.

[Blknight.aus]

bounce on the bull bar or tow hitch.

more than one oscillation (up down then return to normal height) is excessive.

depending on how firm the shockies were to start with anything more than a return to the rest position may be excessive

[101RRS]

I had a 74 Galant and took the shockies off it for a while - made no difference - likewise try bouncing a 101 - ain't going to happen.

I find the best way is to get a mate to drive your car along a B road at about 100kph. Follow along in another car and observe the motion of each wheel in turn. If the wheel tracks along with no obvious bounce then the shockie is OK - certainly for on road use. If there is a is a bit of bounce or a lot then the shockies have failed or are on the way out.

Garry

[bee utey]

Speed humps are useful for shocker testing. If the car does a few wallows after the bump they are probably stuffed. Mind you a top rate shocker can wear to be a just adequate shocker without being actually failed. It all depends on how you want to drive the beast.

[blackbuttdisco]

A few years ago due to financial limitations, I repaced the D1 shockies with a cheap pair. Made an enormous difference, it now stayed on course and didn't wallow all over the road. Bounce test was the same as the 101, didn't happen. Now they are worn out and the new konis are waiting to be fitted.

[onemore]

What if on the speed hump test there is banging noise coming from the rear end?
The girlfriends Honda with 220,000kms does that.

Thanks for the info.
Cheers

[Blknight.aus]

the honda is rooted and needs to be replaced.

Id recommend a D1.

[onemore]

I don't reckon she is going to fall for that one from me, she is amazed how much money I pour into the '93 classic.

mikm

[twr7cx]

What if on the speed hump test there is banging noise coming from the rear end?

My Disco does that. Often at low speeds there is quiet a violent bang noise, but not always, hard to get it to happen when I want it. I still haven't figure out what it is...

[tailslide]

My Disco does that. Often at low speeds there is quiet a violent bang noise, but not always, hard to get it to happen when I want it. I still haven't figure out what it is...

I would guess that it is coming from your rear shocks that have lost their rebound damping allowing the shocks to extend to their maximum length. Hence the bang when you run out of travel... Well that is what is happening to mine at the moment.

I haven't made my mind up as to fitting a 2" lift yet so haven't made a decision on the appropriate shocks to fit. I will probably go with a "cheap" Original Equipment replacement and leave the expensive after market ones for later.

Cheers
Ron

[broonski]

My Disco does that. Often at low speeds there is quiet a violent bang noise, but not always, hard to get it to happen when I want it. I still haven't figure out what it is...

My old rangie did this aswell, I found it was the bushes on the top mount of the rear shocks. The eye on the top of the shock kept chewing out a section of the rubber bush, so it would bang whenever it dropped into a pothole.
Something maybe worth checking out.

Cheers,
Bryce

[Zute]

The OME on my disco just got firmer. So bouncing showed nothing. But 80 000ks is time to change them.
Ive also had a shock on the Zook lock solid with its mate having no oil.
I remove both pairs and compare to each other. Any doubt, chuck em out.

[Yorkshire_Jon]

I was told recently that one of the best ways to check was to feel how warm / hot they are after driving along a corrugated road.

HOT = working
COLD = rooted!

Personally I think you need to take a balenced view on most of the above suggestions and know your car.

I can tell my rears are about stuffed through regular driving and noting the change, bouncing on each corner and operating temp of the casings.

J

[Tombie]

My Disco does that. Often at low speeds there is quiet a violent bang noise, but not always, hard to get it to happen when I want it. I still haven't figure out what it is...

Lifted on stock length shocks will always bang!

It's the shock piston meeting the end of the housing violently...

If you're lifted you need longer shocks!
If you aren't lifted yet - they are hopelessly worn out!

Sent from my iPhone using Forum Runner

[rick130]

I was told recently that one of the best ways to check was to feel how warm / hot they are after driving along a corrugated road.

HOT = working
COLD = rooted!

Personally I think you need to take a balenced view on most of the above suggestions and know your car.

I can tell my rears are about stuffed through regular driving and noting the change, bouncing on each corner and operating temp of the casings.

J

That may show nothing, the performance of a damper over bumps and in pitch, squat and roll are more telling.

I rebuilt some Koni's using a syn fluid, added an insulated thermocouple to the outside of the body and went for a drive down a 30km dirt road at race speeds (ie. as fast as a 300Tdi will go, jumps, sideways on every corner, etc.)
I only had minimal temp rise above ambient, the road just wasn't rough enough and the heat wasn't transfering to the outer tube.
A mono tube damper would have been much warmer.

Basically if you are getting any body float when driving over undulations your dampers have seen better days.
If one or both axles skips or patters when driving fast on a rough road they may be past it

[twr7cx]

Lifted on stock length shocks will always bang!

It's the shock piston meeting the end of the housing violently...

If you're lifted you need longer shocks!
If you aren't lifted yet - they are hopelessly worn out!

Sent from my iPhone using Forum Runner

Cheers. The vehicle has been lifted by the previous owner. Looks to me as though it is still the original shockies. Might be time for me to invest in the replacement OME remote reservoir units...