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Re-lubricating Fluidbloc bushes for R8 upper wishbones

JohnW

Too many posts!
Has anyone done this? It seemed worth asking a wide audience.

The R8 upper wishbone bushes are Fluidbloc, that is like Silentbloc but with the rubber not bonded to the outer part of the bush. Instead it has a textured finish and comes lubricated. After a mere 20 years since I fitted new ones, my upper bushes are not loose or slack at all, but not smooth in action (it's dismantled, so I know from hand action). Seems to me all that is wrong is shortage of lubrication.

Is there any experience out there? I find that there are even mixed experiences with what type of bush is fitted there, some having the Silentbloc bushes as their consistent experience. My spare bushes are Silentbloc, I'd add.

It's worth Googling "Fluidbloc bush" if you aren't sure what they are.

All comments welcome, with thanks.
 

jaahn

1000+ Posts
Hi John :)
Now that is interesting ! I have never heard of them before but I see that they might have some application in the front end of a 8/10 because of the potential difference of loading height. The double bonded bushes do present a significant 'spring' in the system when displaced from the initial tightened position. Whereas these would move to accommodate the unloaded to fully loaded "boot" weight.:rolleyes:

To relube them looks difficult by the diagrams. Sooo if there are no signs of excessive leakage I might try warming them up a 'bit' to make the lube more fluid and fully rotating them in both directions a few times and see what happens. o_O Who knows what lube is in there ?? silicon ?
Good luck Jaahn
PS It is a bad day when you do not learn something !
 

JohnW

Too many posts!
Woo Hoo. A reply!

The good thing about Fluidbloc bushes is that they give the vibration insulation but with the advantages of very low resistance to rotation and allowing larger angles of movement than can be achieved with Silentbloc bushes, which rely on deformation of the "rubber" in the bush.

Porsche apparently rejected them when designing the 911. If the web is to be believed, it was due to concern about service life. I've just got the wishbones out and onto the bench. The ones in the R8 did pull apart when new so I might be able to do it again. I agree silicone grease would be the way to go btw.

Thanks for the warming suggestion. Paint stripping guns are really good for that sort of thing - you don't need a flame!

According to Paulstra's tables, the lower arm Silentblocs have a 30 degree angular capacity, based on their dimensions, but the shorter upper arm bushes, much thinner in the rubber, allow only 20 degrees if Silentbloc. The upper arms are significantly shorter so the arms (and the bushes) move through a greater angle than the lower ones. This is exactly the wrong way around!!

I guess the Silentbloc bushes, which seem to be the only available replacements, must be OK as there are hundreds of these cars out there globally with rebuilt suspension. The same bushes are used on Alpine A110, Matra Djet, and R8 Gordini models.

Thanks for the thoughts. Interesting, isn't it?
 
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Shoji

Renault 17 TL 1312
So maybe the lube has dried somewhat, John? Can they be rejuvenated by a bit of heat, as said above? Worth a try.
The silentbloc helps the suspension come back to it's normal position as apposed to the fluidbloc??? Because then your relying on the other two shock and spring to do that, cancelling out a third helper. Just trying to get my head around the concept...
 
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Exfrogger

1000+ Posts
When I was young and foolish (as opposed to being old and... never mind) I attempted to remove bushes from an upper control arm with a blow torch. (I still use the blow torch to melt the rubber these days but only to get the rubber out so l can hacksaw a grove in the bush casing). What happened was that the rubber separated from the casing and came out easily. Hmm, thinks l, why not just heat the casing of the new one to get the rubber out and slip that in rather than pressing (read: pound with a hammer) the old one out. That I did, and all was peachy.

That said, what I thought I was doing was heating the glue which bonded the rubber to its outer casing so that when I slipped it into the old casing it would rebond when it cooled.

Now maybe I’m reading this wrong, but I thought the of movement came from the inner steel bush sleeve rotating on the pivot pin. With the pin out a bit of steel wool and kero to polish it up, a little Nulon gorilla snot or your favourite rubber-friendly lube on the pin would make it just like a bought one. Maybe a bit of lube under the washers at either end wouldn’t go astray either.

As bits get harder to find, using a two part nolathane product to make your own becomes an option. As does off-setting the inner sleeve to give a little camber change as well.
 

JohnW

Too many posts!
So maybe the lube has dried somewhat, John? Can they be rejuvenated by a bit of heat, as said above? Worth a try.
The silentbloc helps the suspension come back to it's normal position as apposed to the fluidbloc??? Because then your relying on the other two shock and spring to do that, cancelling out a third helper. Just trying to get my head around the concept...
Partly correct, yes. I have the Fluidbloc bushes out now and they pop apart easily. The rubber looks just fine but I remember them being well-lubricated when fitted by me 20 years ago.

The Silentbloc system was developed in the 1950s I think, as all the post-1957 4CVs and Dauphines had it. They are super-cheap and reliable and there are no moving parts to need greasing, complex machining to make etc. When tightened up, the pin locks the inner steel bush so it cannot turn. The outer steel is pressed into the moving part, like a suspension wishbone, and the angular change in the wishbone as the suspension works is taken up in the Silentbloc bush by the deformation of the rubber under torsional loads. The bush's torsional strength is trivial compared with the car's weight and suspension springs. The advantage of the Fluidbloc system is that it has no limitations regarding the magnitude of teh angular change that it can accomodate and little resistance to that movement. I imagine it is rather more expensive to make than Silentbloc.

I read that Porsche considered using Fluidbloc bushes for the 911 but decided to remain with Silentbloc.- long term reliability concerns I suspect.

I now know that there is a procedure for setting up the R8 suspension before tightening the Silentbloc system - get this wrong (as I probably did 20 years ago) and the bushes can be over-stressed by too much rotation. I suspect mine are in that category as the originals lasted 35 years. Of course, there is a chance that I only replaced the upper bushes. I really can't be sure. So maybe they lasted 56 years!!!
 

JohnW

Too many posts!
When I was young and foolish (as opposed to being old and... never mind) I attempted to remove bushes from an upper control arm with a blow torch. (I still use the blow torch to melt the rubber these days but only to get the rubber out so l can hacksaw a grove in the bush casing). What happened was that the rubber separated from the casing and came out easily. Hmm, thinks l, why not just heat the casing of the new one to get the rubber out and slip that in rather than pressing (read: pound with a hammer) the old one out. That I did, and all was peachy.

That said, what I thought I was doing was heating the glue which bonded the rubber to its outer casing so that when I slipped it into the old casing it would rebond when it cooled.

Now maybe I’m reading this wrong, but I thought the of movement came from the inner steel bush sleeve rotating on the pivot pin. With the pin out a bit of steel wool and kero to polish it up, a little Nulon gorilla snot or your favourite rubber-friendly lube on the pin would make it just like a bought one. Maybe a bit of lube under the washers at either end wouldn’t go astray either.

As bits get harder to find, using a two part nolathane product to make your own becomes an option. As does off-setting the inner sleeve to give a little camber change as well.
Thanks Mr ExF.

The Silentbloc system has no rotational sliding at all - it's all in deforming the rubber.

The Fluidbloc system is quite different - the rubber annulus slides against the outer steel part of the bush. Less resistance to movement and unlimited angular displacement. They are meant to be lubricated for life, but mine seem 100% but for lubrication (and I remember what they were like when newly fitted by me). Do you have any lurking in a box?

Thanks to the R8 Gordini and Alpine A110 folk there is steady demand for all these moving parts. I reckon all these "sealed for life" systems have whiskers on them. I fitted grease nipples to the R8 ball joints years ago because they ran low on lubricant and got sticky.

I hadn't thought of an offset top bush to change camber!

Cheers for now.
 

Shoji

Renault 17 TL 1312
I believe the R17 has silentbloc style bushes too. I had the suspension guy across the road swap out the bushes on the wish bones with new ones from Ren 12 shop. I have no press so couldn't do it myself. Could have bought brand new wish bones complete but I didn't. The procedure (from the M.R. 156) for the final tightening of the pins and bushes was to have the car resting normally (without jacks) and torque it up, securing the inner bushes.
Interesting these fluidblocs. What difference is noted? Is it better suspension wise for ride, handling, etc.
 

JohnW

Too many posts!
Yes, it would have several of them I imagine. I don't know how the difference feels. I suspect it's impossible to do a realistic comparison. I guess theoretically the suspension might respond a bit more sharply.

For the R8 there is a factory tool to set the suspension correctly before tightening the bolts. Our mutual friend uses 40 kg in the boot, which makes sense to me. I suspect, but can't remember, that I had mine up on blocks, suspension fully down, when I tightened them 20 years ago. Hence the short life of 20 years and I guess 100,000 km or so.
 

schlitzaugen

1000+ Posts
When you tightened them you probably didn't get the wishboone angle right hence in service they were probably twisted beyond their capacity.

What does the Fluidblock manufacturer say about recommended lubricants?

Some food grade silicone could be the answer as it does not react (it's not supposed to anyway) with anything and it is impervious to water, but why not use just plain old rubber grease?

I have been using a smear of silicone grease (Dow Corning food grade) on heater hoses in all my cars to prevent them welding on spigots/similar and avoid metals corroding with no adverse effect to the rubber over more than 25 years. Hoses come off easily and never leak, and you can see the grease is still there after long years of service. Stops coolant ingress and corrosion of metals too. Never tried it on suspension bushings though.
 

JohnW

Too many posts!
When you tightened them you probably didn't get the wishboone angle right hence in service they were probably twisted beyond their capacity.

What does the Fluidblock manufacturer say about recommended lubricants?

Some food grade silicone could be the answer as it does not react (it's not supposed to anyway) with anything and it is impervious to water, but why not use just plain old rubber grease?

I have been using a smear of silicone grease (Dow Corning food grade) on heater hoses in all my cars to prevent them welding on spigots/similar and avoid metals corroding with no adverse effect to the rubber over more than 25 years. Hoses come off easily and never leak, and you can see the grease is still there after long years of service. Stops coolant ingress and corrosion of metals too. Never tried it on suspension bushings though.
I'm sure you are right about the angle business - it was years after I did the job that I realised that was important. They've only lasted 20 years! The first ones lasted 35 years.

All I can find online regarding Fluidbloc bushes is "lubricated for life". Plain old rubber grease might actually be the right answer although I am inclined to silicone grease. Do you have a brand/identification for the grease you have?

Good idea on the hoses - I use rubber grease but it isn't there when you pull the hoses off years later, unlike your silicone description. Hence my interest in silicone grease.

Thanks for that.
Lower right front wishbone bush 2 sml.jpg
 

Armidillo

1000+ Posts
I'm sure you are right about the angle business - it was years after I did the job that I realised that was important. They've only lasted 20 years! The first ones lasted 35 years.

All I can find online regarding Fluidbloc bushes is "lubricated for life". Plain old rubber grease might actually be the right answer although I am inclined to silicone grease. Do you have a brand/identification for the grease you have?

Good idea on the hoses - I use rubber grease but it isn't there when you pull the hoses off years later, unlike your silicone description. Hence my interest in silicone grease.

Thanks for that.
View attachment 122909
Yep, looks like all it needs is a bit of grease and it should be as good as new!
 

JohnW

Too many posts!
Yep, looks like all it needs is a bit of grease and it should be as good as new!
I neglected to mention that the wrecked bush, one of four I'd add, is a Silentbloc bush from the lower wishbones. The upper Fluidblock ones seem just fine but need lubrication.

Very funny! :)
 

jaahn

1000+ Posts
Hi :)
I would not argue against schlitz's suggestion but good old rubber grease is specifically made for rubber and metal interaction and easy to get also. But either way how are you proposing getting it in to the working area. It is probably in there but just needs a bit of activation(heat) and redistrubition(turning the parts) a few times and even a bit of "tapping' with a piece of wood or rubber hammer.
Is it worth pulling the wishbone out and just getting a drill and a way of driving the inner around at a modest speed for a while both ways to 'free it up' ;) not too fast or might get too hot inside.

The way to get good unstressed life from the Silentbloc bushes is to tighten the nut with the car at the usual height on the wheels. This may not be with 40Kg in the boot for your car. Perhaps it never has anything in there. Put your weight in the drivers seat and possibly a passenger seat weight also depending on the 'normal' usage now a days.
Jaahn
 
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JohnW

Too many posts!
Why the two different types, John?
Good question. My conjecture is that the upper bushes, being attached to shorter wishbones than the lower ones, turn through a greater angle than desirable for Silentbloc bushes, which rely on the rubber in the bush deforming - nothing slides mechanically. Also the Fluidbloc system has less resistance to rotation. So back in the late 1950s when they engineered the R8, their first car with ball joints instead of king pins, someone made that decision.

I'm not sure that the Fluidbloc bushes are available as spare parts now. And the Silentblocs supplied have much less tolerance for rotation because of their small dimensions. Still, hundreds of people must be using them.
 

JohnW

Too many posts!
Hi :)
I would not argue against schlitz's suggestion but good old rubber grease is specifically made for rubber and metal interaction and easy to get also. But either way how are you proposing getting it in to the working area. It is probably in there but just needs a bit of activation(heat) and redistrubition(turning the parts) a few times and even a bit of "tapping' with a piece of wood or rubber hammer.
Is it worth pulling the wishbone out and just getting a drill and a way of driving the inner around at a modest speed for a while both ways to 'free it up' ;) not too fast or might get too hot inside.

The way to get good unstressed life from the Silentbloc bushes is to tighten the nut with the car at the usual height on the wheels. This may not be with 40Kg in the boot for your car. Perhaps it never has anything in there. Put your weight in the drivers seat and possibly a passenger seat weight also depending on the 'normal' usage now a days.
Jaahn
Thanks. Yes, I reckon I probably got the tightening wrong last time, in about 2000. The Fluidbloc bushes actually push apart, so it is easy to relubricate one the wishbones are out, and mine are OUT now! The bush on the left is the Silentbloc replacement and the two images on the right are the Fluidbloc bush pressed apart (easily).
Upper wishbone bushes of both types sml.jpg
 

Shoji

Renault 17 TL 1312
Quite interesting John. I also have been busy today ripping out the rear axle to replace the trailing arms (come with new bushes).
You must have spurred me on.
 

Dapco Auto France

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