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Don't Replace your Front Shocks/Struts until you've seen this!

12K views 16 replies 7 participants last post by  matt_tr 
#1 · (Edited)
My front struts were worn (W639 Vito) in that the front was bouncing. At just over 80,000km I guess it's to be expected the oil would be past it's use by date

I bought a set of new KYB's.

What I find as total hypocrisy is the fact the OEM Sachs struts have the top bushing pressed in and the outside tube peened over making them a sealed unit preventing you from dumping the oil. The new KYB's are the same.

In days gone by struts had a threaded collar allowing you to pull out the shaft and replace the oil. But what do Sachs, KYB etc want and how do they generate revenue? ... by selling as many struts as they can. They have no incentive to make them in way to allow you to replace the oil. The high end competition struts have the threaded collar arrangement.

I'm sure the manufacturers will say it's a cheaper way of manufacturing which is probably true, however with modern robot manufacturing the additional cost would be peanuts. I'd gladly pay a few dollars more to have the threaded collar.

I took to the Sachs unit with a cutting wheel and opened it to see what makes it tick. The valves, shim stacks, inner cartridge tube, shaft and the seal were perfect. There was nothing wrong other than the fluid was tired plus it smelled like whale oil. It didn't appear to be good quality hydraulic oil.

The basic structure of the strut is the same as the cartridge forks on my track motorcycles. We don't throw the front forks out when the oil gets tired ... we replace the oil! I replace the front suspension fluid on my track bikes every 20 hours and the rear suspension once per year.

The hypocrisy is we are forced to throw out perfectly good struts just because the oil needs replacing ... in the next breath our Governments are rabbiting on about Climate change and telling us we need to reduce our carbon footprint and greenhouse gases. The whole thing is a con and a contradiction.

It's bloody nonsense when the consumer system is based around planned obsolescence forcing is to throw things out and buy another ... but at the same time we're supposedly meant to reduce our carbon footprint. It's simple ... buy less stuff. In the next breath governments and corporations complain about low or no growth. You can't have it both ways.

Buy less stuff = less carbon.

I put the the thinking cap on and have been able to make a cheap modification to allow the struts to be drained and re-pressured. I got hold of another second hand Sachs that was going to be thrown out so I built a reconditioned pair and fitted them to a friends 2007 W639 Vito.

We filled the refurbished struts with full synthetic ATF and pressured to 50psi. ATF is great hydraulic fluid. The The results were truly outstanding. In fact I'd say these struts perform better than my new KYB's. This method would work on most front struts. I'll do it to my W204 C320CDI.

I'm going to make the same modification to my new KYB's so I can replace the oil every few years.

 
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#2 · (Edited)
Very strange conclusion.
When we have lifetime transmission and differential oils, I did own 30 years old tractor with hydro-static transmission and 20 years old hydraulic oil in it did not require change. We are talking about oil used for driving field machine, where extreme dust, high temperatures and overloading are normal way to treat them.
Hydraulic oils don't have any chemistry in them and beside mechanical contamination - they are truly lifetime fluids.
I understand that struts have no oil filters, but if you are saying the mechanics were flawless, while oil was bad, that contradict all the science.
Anyway, my family drives E-class for almost 20 years and several cars have 260-300,000 miles on original struts. I hope that will continue.
Now on commercial forum , you will always find "opinions" that you should keep dropping new parts in your vehicles. My pointing that this is not necessary got me banned in couple of those places.
Go figure it out.
 
#3 ·
To the contrary I think science says oils will gradually degrade over time with the heat cycles and contamination.

I change the oil in my motorcycle front suspension every 20 hours because you can feel the damping starting to fade. Replace the oil and the suspension feels good again. Racing pushes the limits of all the lubricants. The competition race car struts have threaded collars to allow the damping oil to be changed ... and it's changed for for every race meeting.

My struts were bouncing over speed bumps and the front would hit the pavement. I changed to new struts and now I can't get the front to hit the pavement because the spring is controlled.

There's been plenty written about "filled for life" transmissions. It's nonsense propagated by the manufacturers to get through the typical 4 to 5 year lease period. Read about all the failed 7GTronic transmissions because they'd never been serviced. Frequent lubricating fluid changes are the answer to component life and availability.

You're right in that "opinions" are everywhere especially behind the counter of a Mercedes dealer. I'm a degree qualified Engineer and have researched this stuff.
 
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#4 · (Edited)
I had oil classes, but that was long ago to make it non-substantial.
You don't have heat issue in shock absorbers and I serviced 5-sp with I believe was original ATF at 230,000 miles. Never had a problem, but figured out after 230 k the car deserves a treat.
Science says the oils have infinite shelf life and that applies to motor oils, who have very strong % of detergents and chemicals antidotes.
When it comes to racing, in some competitions they have 3 engines for single competition.
Years ago I was involved in flying models.
For "combat" airplane competition I was allowed to bring 3 model airplanes and often that was not enough for 3 minutes the combat lasted.
Bottom line - comparing racing bicycle to limousine is out of this World.
 
#5 ·
There's no point debating as we all have different experiences. Shocky's get very hot depending on how they're used. I recently did a desert crossing through Australia on very rough roads and a Toyota Landcruiser had a rear shock catch on fire!

A limo cruising around town is not going to stress the suspension so will go a long time on the original shock oil.

The facts with my case are:

My W639 Vito had 85,000km on the clock and the front was bouncing several times after a bump. This vehicle is nearly 10 years old and has been driven on a variety of roads and conditions. I had it tested on a suspension dyno and it showed the extra rebound strokes like a pogo stick on the graph. The recommendation was the front shock/struts needed replacing as the rebound damping wasn't up to standard. I purchased new KYB struts. After installation no more bouncing over bumps. The rebound of the spring was being controlled again.

Conclusion:

The damping fluid in the original struts was not controlling the spring rebound as the oil properties had deteriorated. The seals were still good and they were still under pressure. After replacing the oil with good quality synthetic ATF .... which is a good hydraulic fluid with seal conditioners and anti foaming agents the front struts/shocks again performed like new and controlled the rebound damping as good or better than the new ones.

All I'm trying to say is if your front struts have got to the point where the rebound is not being controlled it's possible with most of them to make the modification I designed and refill and pressure the original struts and they will perform like new again. This only applies if the top seal is still good. If the seal has gone it can't be replaced and you'll have to buy new struts.

The alternative is you throw out perfectly good mechanical components and buy new ones ... which is exactly what the manufacturers of struts want you to do 'cos they sell more struts, more revenue, more growth, more bonuses.

With the 722.6 transmissions I change the ATF every 3 years. Others may want to keep going and never change it as it's an individual choice.

I'll copy into another post what the Technical Director of the Mercedes Benz Club of America says about the "filled for life" transmissions. He's a Mechanical Engineer.
 
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#6 ·
How’s this article from a Mechanical Engineer ex the nuclear power industry who’s the Technical Director for the Mercedes Benz Club of America. He says a dealer serviced MB is actually a black mark for the car.

How many ads selling a used Mercedes-Benz have you read that stated in so many words “. . . always dealer maintained . . .” Supposedly this assures a potential buyer that the car has had meticulous maintenance throughout its life. What if I told you that a few items NEVER receive any attention if only the M-B maintenance program is followed? In fact, some dealers neglect to perform some of the more important items listed on the maintenance sheets.

Following is a summary of the often-neglected maintenance items on M-B automobiles.

Power Steering fluid and filter change

M-B service called out for the power steering (PS) system usually consists of simply checking and topping up the fluid level. No mention is made in M-B maintenance documents to change the fluid or the filter. (M-B did away with the PS filter as a cost saving measure in late 1999). The power steering on your Mercedes Benz is a simple hydraulic system that uses automatic transmission fluid or M-B special PS fluid. As the miles go by, the fluid becomes contaminated with wear metals, moisture and dirt. In my experience, earlier models with a PS filter in the reservoir seem to have fewer problems with the PS system than the newer models without this important feature. The filter part # for these earlier systems is 000 466 16 04 – (about the size of a hockey puck).
Fluid and filter change is relatively easy – I use a “feed and bleed” technique which involves running the engine to pump fluid through the system into a container while pouring new fluid into the reservoir. When new clean fluid emerges from the drain hose, shut off the engine, install a new filter, and top up the fluid level – you’re done. For a list of cars equipped with a power steering filter and a detailed step-by-step procedure, contact technical Director George Murphy at perfanalysis@comcast.net.

Hydraulic fluid and filter change

Self-leveling rear suspension was fitted as standard equipment to the rear of U.S. Model W123, W124., W126, W203 and W210 models to maintain the car level under expected loads. Some gray market S-class cars and all model 6.9 cars have hydropneumatic suspension at the front and rear for full suspension of the car without traditional springs.
Note: The power steering and self leveling systems are combined in the late W124, W203 and W210 models with ASR, so they use the same fluid and filter.
Fluid part # 000 989 91 03 Filter part # 002 184 55 01
Being a mechanical engineer with a 30-years experience in nuclear power plants, I had occasion to work on large steam turbine hydraulic controls at several plants. These hydraulic systems had rigorous maintenance requirements set by the equipment supplier to maintain these huge turbines on-line generating electricity. But I was surprised to find no reference in M-B maintenance booklets for periodic care of the self-leveling suspension on our Mercedes-Benz cars - after all, the operating principles, fluids and components are similar and are subject to wear and contamination much more severe than the systems I worked on at the power plants.
In my experience with this system on Mercedes-Benz automobiles, I found neglect to be the prime cause of failures and leaks in the system. A M-B that receives so-called dealer maintenance all its life would receive hardly any attention to the hydraulic system other than topping up the reservoir from time to time. Hydraulic systems need periodic fluid and filter replacement to keep them in top working order. I recommend the fluid and filter be changed at 30,000 to 40,000 mile intervals, the same as the transmission and the power steering systems.

Automatic transmission fluid and filter

M-B initiated so-called lubricated-for-life 722.6 automatic transmissions in 1996 models. Unless this component shows obvious leakage, the fluid level is never checked. If you don't service the transmission, you will have problems - most automatic transmissions from 1996 to 2005 are touted as needing no fluid or filter replacement for life. Under these conditions, the “life” is about 80,000 to 100,000 miles - long after the warranty has expired. In addition, M-B then recommends replacement of these "lubed for life" transmissions at 100,000 miles if they are not operating properly. I have seen a number of these transmissions at my local independent M-B mechanic's shop with sludgy, dirty fluid at 80,000 miles or so because surprise (!) the fluid and filter were not changed as with the older models . . .
LESSON: Change fluid and filter in ALL automatic transmissions every 30,000 to 40,000 miles as used to be required by M-B prior to 1996 - that's why the older units lasted so long. The newer 722.6 transmissions are no more resistant to contamination and moisture than the older ones - and now they have computers INSIDE the case, leading to electronic problems from increasing conductivity of the operating fluid due to moisture, wear metals and manufacturing debris.
The wear metals, mostly iron and aluminum, originate from machining during manufacture and initial wear-in of the new parts. Silicon originates from sand left over from the casting process - it is not possible to clean the gearbox castings completely as microscopic particles lodge in the pores of the parts. The normal "breathing" that occurs with temperature changes draws in moisture and dust, which can only be flushed out with periodic fluid changes.
In 2001 M-B did initiate installation of a magnet in the transmission pan to attract any metal particles – these magnets may be used in any M-B automatic transmission and are a good idea. The part # is 169 371 00 03 – just lay the magnet in the rear of the pan so it does not interfere with the filter.
In 2006, M-B changed service procedures to include automatic transmission fluid and filter change at around 35,000 miles. For a do-it-yourselfer, web site installuniversity.com shows how to change transmission fluid in a 722.6 unit, along with change of the transmission data plug connector. (More on this in a later article)
Parts needed: Transmission filter 140 277 00 95
Transmission pan seal 140 271 00 80
Dipstick tube closure 140 270 00 91 + 140 991 00 55
722.6 Mercedes Benz transmission dipstick – zdmak.com
Transmsiion fluid 001 989 21 03 10 or Fuchs 3353 (8 liters)
Based on this experience, I recommend that all gearbox lubricants be changed at about 30,000 to 40,000 miles – even better is at 5000 miles from new to remove initial contamination outlined above. REMEMBER - no gearbox is "lubricated for life".

Manual transmission and differential fluid change

An almost forgotten component on our cars is the rear axle/differential gear box. Dealers rarely remember to check the oil level, let alone periodically change the oil or clean the gearbox vent. The prime reason for rear axle seal failure is plugging of the gearbox vent. You will pay dearly for seal replacement, as it is not a simple job. The vent should be cleaned and the oil changed at least every 30,000 to 40,000 miles; more frequently under dusty or muddy conditions.
Before you changing these fluids, drive the car for at least 20 minutes at better than 40 mph. This suspends contaminants so that they will drain out with the oil, and it makes everything drain faster, especially the heavy gear oil. For do-it-yourselfers, the differential takes between 1 and 2 quarts, so buy 2 (you're going to spill some). Don't worry about measuring what you put in the gear case; just fill it until it starts to run back out the fill hole. Then let it drip awhile -you don't want it overfilled. (Hint: ALWAYS open the gearbox FILL plug first to assure you can fill it after draining out the old fluid.) Consult your owner’s manual for correct gear oil to use in manual transmissions, transfer cases and differentials.

Wheel bearing service

Front wheel bearings are almost completely neglected by M-B maintenance service. Unless they are noisy or showing looseness, they never receive proper service. In my experience, the grease should be at least checked at the 90,000 mile service – in several M-Bs I have owned, I found the factory grease was getting a little stiff by this mileage and in need of changing.
Use M-B wheel bearing grease part no 002 989 00 51 10 or a good grade of lithium high temperature bearing grease - Kendall Blue comes to mind. Of course, buy new inner hub seals.
Pull a bearing cap and look at the grease - if it is stiff and wax-like, it is long past time for bearing re-pack. Anyway, I do bearing grease at 90,000 miles interval (third 30,000 mile service). M-B specifies their green high temp grease in all cars since 1986.
If your bearings are OK, but if the hubs are coming off anyway for brake rotor change, change the bearing grease and install new inner seals. Thoroughly clean the hub and bearings of ALL old grease. (DO NOT SPIN THE BEARINGS at high speed with an air gun to dry them - be gentle with the air. Some mechanics like to have fun by making that high pitched whine using compressed air to spin and dry out cleaned bearings - it is really hard on the bearings to do that.)
Pack bearings by hand with M-B grease - save all the excess - weigh out the correct # of grams according to the M-B chassis manual for your car and pack it into the hub. There's a reason for the specified grams of grease for the bearings and inside the hub. Too much leads to overheating and too little starves the bearings of grease. The grams specified for inside the hub and the bearings just fills the hub cavity such that centrifugal force during rotation forces the grease outward in both directions to continually pressurize the bearings and keep them lubricated. It has been shown that the grease actually "circulates" inside the hub and through the bearings to keep them lubricated - that's why properly-lubricated M-B front wheel bearings can last so long, and that is the reason for that specified grams of grease.
Use the rest of the grease to fill the hub cap. In this manner the inside seal stops the grease from leaving the bearing due to centrifugal force, and the cap, being full of grease, keeps the grease inside the hub and outer bearing area.
A 150-gram tube of M-B grease will do both front wheels - about 60 grams per hub plus 30 grams for bearings - simply follow the M-B factory chassis manual procedure.
Starting in 1986 all models use the M-B “green” grease part no. 002 989 00 51 10. This should be used in all M-Bs of any age. DO NOT MIX GREASE TYPES – thoroughly clean all parts of old grease before adding new grease or unexpected results may occur.
Be sure to set the bearing free play according to the M-B shop manuals for your car.
 
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#7 ·
So now from racing principles you are suggesting to follow nuclear plat and steam turbines principles to our cars?
The first rule of judging the oils is to never judge them by look.
So let me repeat. I drove lot of high mileage vehicles.
Often I don't have 100% records, but the mentioned 230,000 miles ATF had goo-like consistency on bottom of the pan. New fluid made softer gear changes, but the transmission never had a problem before.
So we can discuss if those transmission who failed at 100k did so due old ATF, or per my observation main problem with those transmissions is $10 pilot bushing and unqualified mechanics are replacing whole transmission simply becouse they don't know better.
And don't take it that I don't trust your need for new shocks at 80k km.
In my younger years I drove Fiats, where 30,000 km on shocks was good before replacement.
Water pumps usually lasted 50,000 km, starters maybe 60k.
Still not anything I would dare to compare to E class we are using right now.
If you feel you are right about oil replacement in shocks, why don't you make a plug in them and follow your own advise?
I had similar feeling with installing filter minder (a gauge) on our cars and recorded 80,000 miles on air filter before sold the car and the gauge did not even went into yellow zone.
Same with removal of engine fan on our diesel that was found unneeded with good coolant and proper maintenance even in 114F (45C) weather.
Making new rules, no matter how good is always going to have lot of skepticism.
My fanless car become legend not only on this forum and even some used the fact in their propaganda stunts.
So here is your chance to become famous.
 
#8 · (Edited)
If you read the last sentence of my OP you'll see I've already said I'll be making the same modification to my new KYB's ... not to become famous but to allow me to change the hydraulic oil every few years.

I've also run a vehicle without the belt driven fan ... but not when using it in heavy traffic. I fitted an electric fan with a temperature switch.
 
#10 · (Edited)
Thanks Dean. Well motorcycle fork oil is very expensive. Motorcycles used to have ATF in their forks until the marketing guys realised they could charge a lot more if it was called salubrious fork oil!

I have at times used ATF in modern cartridge forks when I was racing state championships in the 1990's and it's fine. However the trend has changed to use much lighter oils which now sort of rules out ATF as it's about 10W whereas we use 2.5W to 5W max in our forks these days.

Also sports motorcycles have far more sophisticated suspension due to the ratio of sprung to unsprung weight being very low so they require closer attention to oil weights, springs etc. Motor vehicle suspension can be far less sophisticated due to the ratio being very high. The greater the sprung weight to unsprung weight the less affected are the vehicle and occupants to bumps on the road. It's commonsense really as the massive sprung weight is harder to knock off course.

With my track bikes I'm very careful with suspension and set up due to my life depending on it. If I could find an ATF that's about 5W I'd use it in my track bikes to save money but I'm pretty sure its closer to 10W or even more.

So what I'm saying is you don't need to get too anal about motor car suspension ... as long as a good hydraulic oil is used and it controls the wheel that's all you need to worry about. Logic tells me it needs to be heavier oil as the wheel and the other sprung weight has a lot more mass than the wheel on my bike. So I took a guess that ATF would be about right (around 10W or a bit more) and it appears to be on the money. In fact when struts first appeared on cars they often used to be filled with ATF.

ATF is a good hydraulic oil. It has anti foaming agents and seal conditioners and is designed to be pumped and take high temperatures so it's an ideal suspension oil. The internal cartridge in the struts is sucking the ATF into it when the sprung is rebounding and pumping it through the rebound valve and pushing the ATF back out again through the compression valve when the spring is compressing. ATF can handle this easily.

We did a road trip on the weekend to a track a few hours south and my mates 2007 Vito with these modified struts worked brilliantly on some very potholed unsealed sidetracks associated with some major rural road works. At 80km/hr on these gravel tracks the Vito was absorbing the bumps in it's stride with no wallowing or discomfort.

The reason I went public with what I did was to try to save others some money. In this country a dollar saved is two dollars earned due our high income tax rates. I'm certainly not wanting to be famous ... I'm only passing on what I've learnt to try to help a few others who want to take control.

I'm fed up with governments and corporations constantly sticking their hand in my pocket.
 
#11 · (Edited)
Economy make huge difference for sure. Since I did not buy shock in last 20 years - I have no idea how much they cost in USA, but I am still comparing economics, where in my native Poland people are still buying "rust buckets" and put 2-3,000 hr to repair them as the pricing still makes it economical.
In California fender-bender will put 10 years old car on junk yard as repair will exceed car value. We have no rust.
So even if shock absorbers would have drain plugs for oil change, I doubt Californians would pay mechanics $500 for shock oil change on regural basis.
And again, our shocks last 300,000 miles easy.
 
#12 ·
My front struts were worn (W639 Vito) in that the front was bouncing. At just over 80,000km I guess it's to be expected the oil would be past it's use by date

I bought a set of new KYB's.

What I find as total hypocrisy is the fact the OEM Sachs struts have the top bushing pressed in and the outside tube peened over making them a sealed unit preventing you from dumping the oil. The new KYB's are the same.

In days gone by struts had a threaded collar allowing you to pull out the shaft and replace the oil. But what do Sachs, KYB etc want and how do they generate revenue? ... by selling as many struts as they can. They have no incentive to make them in way to allow you to replace the oil. The high end competition struts have the threaded collar arrangement.

I'm sure the manufacturers will say it's a cheaper way of manufacturing which is probably true, however with modern robot manufacturing the additional cost would be peanuts. I'd gladly pay a few dollars more to have the threaded collar.

I took to the Sachs unit with a cutting wheel and opened it to see what makes it tick. The valves, shim stacks, inner cartridge tube, shaft and the seal were perfect. There was nothing wrong other than the fluid was tired plus it smelled like whale oil. It didn't appear to be good quality hydraulic oil.

The basic structure of the strut is the same as the cartridge forks on my track motorcycles. We don't throw the front forks out when the oil gets tired ... we replace the oil! I replace the front suspension fluid on my track bikes every 20 hours and the rear suspension once per year.

The hypocrisy is we are forced to throw out perfectly good struts just because the oil needs replacing ... in the next breath our Governments are rabbiting on about Climate change and telling us we need to reduce our carbon footprint and greenhouse gases. The whole thing is a con and a contradiction.

It's bloody nonsense when the consumer system is based around planned obsolescence forcing is to throw things out and buy another ... but at the same time we're supposedly meant to reduce our carbon footprint. It's simple ... buy less stuff. In the next breath governments and corporations complain about low or no growth. You can't have it both ways.

Buy less stuff = less carbon.

I put the the thinking cap on and have been able to make a cheap modification to allow the struts to be drained and re-pressured. I got hold of another second hand Sachs that was going to be thrown out so I built a reconditioned pair and fitted them to a friends 2007 W639 Vito.

We filled the refurbished struts with full synthetic ATF and pressured to 50psi. ATF is great hydraulic fluid. The The results were truly outstanding. In fact I'd say these struts perform better than my new KYB's. This method would work on most front struts. I'll do it to my W204 C320CDI.

I'm going to make the same modification to my new KYB's so I can replace the oil every few years.

Are the Sachs front shocks not gas
 
#13 ·
They're pressurised. We just used air and they're still going well.
 
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#14 ·
hi guys

i bought new shock absorber to vito 2006 111 cdi,brand is sachs 311 645 model,but its hitting too hard and hitting like a punch to front side,its made in turkey,zf sachs has open a fabric here,im wondering what is the problem? i have to change it with export ones? or do you have any suggestion?

note car specialist has checked theres no noise while turning the wheel,he said he didnt see any problem,but i feeling the hitting on sharp bulges,even front glass gets noises

thank in advance
 
#15 ·
Čaute ľudia

Kúpil som si nový tlmič do vito 2006 111 cdi, značka je model sachs 311 645, ale naráža príliš tvrdo a udiera ako úder do prednej strany, je vyrobený v mori, zf sachs tu otvoril látku, zaujímalo by ma, čo je to problém? musím to zmeniť za exportné? alebo mate nejaky navrh?

všimnite si, že špecialista na autá skontroloval, či pri otáčaní volantom nie je žiadny hluk, povedal, že nevidí žiadny problém, ale cítim nárazy do ostrých hrbolčekov, dokonca aj predné sklo vydáva zvuky
ahoj mam vianoce s pohodlnym zadnym podvozkom - vzduchove vankusy. Idem meniť predné tlmiče komplet aj s horným ložiskom aj pružinou. Chcel som ti dať aj vrecúška, ktoré si mi dal, ale nechcem, aby jazda bola ťažká, ale pohodlná. Máte nejaké ďalšie odporúčania? A čo KYB?
vopred dakujem
 
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