Bluemoon
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| posted on 4/7/13 at 02:46 PM |
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Any experiance of polybush grease nipples?
Hi all,
Thinking of fitting grease nipples to the poly-bush housings to help keep the bushes from seizing up, what are peoples thoughts on this:
This would allow a simple grease service without dismantling the whole lot.
Things I wonder:
1) Not much wall thickness to fit even a 6mm one?
2) Will they cause more problems than they solve?
3) What orientation to fit them (away from the road I guess!)..
Cheers
Dan
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SCAR
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| posted on 4/7/13 at 03:08 PM |
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Polybushes are designed to not require greasing (other than during assembly). I raised this question with a manufacturer and was told that they had
maintenance free polybushes, correctly fitted, lasting up to 60k miles on production cars. If that's true your wishbones would need replacing
before the polybushes do. If you go ahead be careful what you use as I have read that some greases can cause the polybushes to fail.
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Slimy38
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| posted on 4/7/13 at 03:28 PM |
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Someone suggested it to me when I was asking about polybush greasing. There was a picture of them fitted, but to me it seemed like overkill. Mind you
it was on a track car where poorly moving suspension could possibly be the difference between first and last.
Polybushes will not seize up, generally it's metal on metal that would seize. They might bind, they might tear, and they might disintegrate. But
those are very big 'mights'!
Have a look here for the question I posed not too long ago, and the approach I intend to use;
http://www.locostbuilders.co.uk/viewthread.php?tid=183165
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MikeRJ
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| posted on 4/7/13 at 03:59 PM |
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quote:
Originally posted by Slimy38
Polybushes will not seize up, generally it's metal on metal that would seize. They might bind, they might tear, and they might disintegrate. But
those are very big 'mights'!
They can "seize" up leading to broken wishbones as witnessed by several posts on here in the past. The problem is when a mild steel crush
tube is used, which rusts and prevents the bush from turning on the tube, which then puts very high cyclic forces into the welds joining the bush tube
to the wishbone arms.
More to the point, the bloody things have an annoying tendency to squeak once the initial assembly lubrication has been squeezed out, so a grease
nipple would be great IF it was capable of actually pushing any grease between the bush and crush tube. I'd only use silicone grease (or other
types that are fully compatible with polyurethane) though.
Personally I avoid using them unless I have to, as they regularly fail to live up to the long life claims stated by the manufacturers. We were
replacing them on a tarmac rally Pug 205 every few events at one stage as they just fell to bits (Superflex). Now running standard road bushes which
last far longer, though changed every year just for piece of mind.
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Not Anumber
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| posted on 4/7/13 at 04:09 PM |
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I'd be interested in knowing more as the polybushes on the back of my 8 year old Indy creak. I'd wondered about dismantling them to apply
some light grease - but of course which grease is the question.
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Slimy38
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| posted on 4/7/13 at 05:02 PM |
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quote:
Originally posted by MikeRJ
quote:
Originally posted by Slimy38
Polybushes will not seize up, generally it's metal on metal that would seize. They might bind, they might tear, and they might disintegrate. But
those are very big 'mights'!
They can "seize" up leading to broken wishbones as witnessed by several posts on here in the past. The problem is when a mild steel crush
tube is used, which rusts and prevents the bush from turning on the tube, which then puts very high cyclic forces into the welds joining the bush tube
to the wishbone arms.
Ah ok, that makes sense. Didn't really consider the crush tube as being the bit that causes the seizure.
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rusty nuts
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| posted on 4/7/13 at 06:30 PM |
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My Luego supplied polybushes had crush tube that were 2 short which caused rock hard suspension and loads of squeeks . Skimming the outer surface of
the top hat section on each bush to ensure that the wishbone rotated freely around the crush tube sorted all of the problems. I did use rubbergrease
when reassembling which may or may not have helped . I suspect had I left the bushes as they were I would have suffered wishbone failure
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iank
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| posted on 4/7/13 at 06:38 PM |
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quote:
Originally posted by MikeRJ
...
Personally I avoid using them unless I have to, as they regularly fail to live up to the long life claims stated by the manufacturers. We were
replacing them on a tarmac rally Pug 205 every few events at one stage as they just fell to bits (Superflex). Now running standard road bushes which
last far longer, though changed every year just for piece of mind.
Which standard road bushes are suitable for locost wishbones? Or is this just the Pug?
--
Never argue with an idiot. They drag you down to their level, then beat you with experience.
Anonymous
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Slimy38
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| posted on 4/7/13 at 07:36 PM |
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quote:
Originally posted by iank
quote:
Originally posted by MikeRJ
...
Personally I avoid using them unless I have to, as they regularly fail to live up to the long life claims stated by the manufacturers. We were
replacing them on a tarmac rally Pug 205 every few events at one stage as they just fell to bits (Superflex). Now running standard road bushes which
last far longer, though changed every year just for piece of mind.
Which standard road bushes are suitable for locost wishbones? Or is this just the Pug?
In the original book (the £250 book), it lists;
quote:
18 x 1.5 inch(38mm) wide metalastic bushes with 1 in (25mm) o.d. and 7/16 in (11mm) i.d. as used in Triumph Heralds.
Although I don't know whether they're still available, or even fit the revised wishbones!!
[Edited on 4/7/13 by Slimy38]
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iank
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| posted on 4/7/13 at 08:08 PM |
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quote:
Originally posted by Slimy38
quote:
Originally posted by iank
quote:
Originally posted by MikeRJ
...
Personally I avoid using them unless I have to, as they regularly fail to live up to the long life claims stated by the manufacturers. We were
replacing them on a tarmac rally Pug 205 every few events at one stage as they just fell to bits (Superflex). Now running standard road bushes which
last far longer, though changed every year just for piece of mind.
Which standard road bushes are suitable for locost wishbones? Or is this just the Pug?
In the original book (the £250 book), it lists;
quote:
18 x 1.5 inch(38mm) wide metalastic bushes with 1 in (25mm) o.d. and 7/16 in (11mm) i.d. as used in Triumph Heralds.
Although I don't know whether they're still available, or even fit the revised wishbones!!
[Edited on 4/7/13 by Slimy38]
Thanks, should just have looked in the book.
Will probably be these http://www.ebay.co.uk/itm/Triumph-Spitfire-Herald-Vitess-GT6-Front-Wishbone-Bush-Set-of-8-119451-/300922888233 - very cheap!
--
Never argue with an idiot. They drag you down to their level, then beat you with experience.
Anonymous
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BenTyreman
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| posted on 4/7/13 at 09:11 PM |
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After a wishbone failure due to mild steel inserts I now have grease nipples fitted. No ill effects after 18 months/7000 miles using CV lith-moly
grease. No squeaks at all and the suspension has very low stiction. I also have thin teflon shims between the ends of the polybushes and the brackets
to further reduce friction.
[Edited on 4/7/13 by BenTyreman]
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Bluemoon
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| posted on 4/7/13 at 10:14 PM |
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quote:
Originally posted by BenTyreman
After a wishbone failure due to mild steel inserts I now have grease nipples fitted. No ill effects after 18 months/7000 miles using CV lith-moly
grease. No squeaks at all and the suspension has very low stiction. I also have thin teflon shims between the ends of the polybushes and the brackets
to further reduce friction.
[Edited on 4/7/13 by BenTyreman]
Sounds good
My car has the squeaks I think I may try you solution before I have a real issue!
How did you make the shims?
What size grease nipples? M5 seems the smallest I have found might give some a try.
Did you replace the inserts with stainless steel ones (I may investigate if Haynes roadster ones fit as they are easy to find in ss).
Dan
[Edited on 4/7/13 by Bluemoon]
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BenTyreman
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| posted on 4/7/13 at 10:23 PM |
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It was actually 30 months/12,000 miles ago. Fitted the smallest grease nipples I could find. They are just drilled and tapped into the tubes at the
end of the wishbones. I check mine occasionally to ensure there are no cracks propagating from the hole. No problems so far.
Bought some 0.5mm teflon sheet on ebay and cut out circles. Stamped a hole in the middle that was larger than the crush tube. Filed down the wishbone
to accommodate the extra 1mm. The tricky part is reassembling the wishbone into the bracket without the teflon washer slipping out of position.
I did indeed replace the mild steel inserts with stainless steel. I got a full replacement set from Saturn Sportscars in Hartlepool. I believe they
are sold as Haynes Roadster (I have an MK).
[Edited on 4/7/13 by BenTyreman]
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Bluemoon
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| posted on 5/7/13 at 10:21 AM |
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quote:
Originally posted by BenTyreman
It was actually 30 months/12,000 miles ago. Fitted the smallest grease nipples I could find. They are just drilled and tapped into the tubes at the
end of the wishbones. I check mine occasionally to ensure there are no cracks propagating from the hole. No problems so far.
Bought some 0.5mm teflon sheet on ebay and cut out circles. Stamped a hole in the middle that was larger than the crush tube. Filed down the wishbone
to accommodate the extra 1mm. The tricky part is reassembling the wishbone into the bracket without the teflon washer slipping out of position.
I did indeed replace the mild steel inserts with stainless steel. I got a full replacement set from Saturn Sportscars in Hartlepool. I believe they
are sold as Haynes Roadster (I have an MK).
[Edited on 4/7/13 by BenTyreman]
Hi Ben,
Thanks, sounds like a good plan.
What direction did you make the grease nipples face?
I wonder if they are pointing down on the lower bones weather they are vulnerable to being ripped out?
Good point about cracks starting at the nipple hole, I had not thought of that!
Cheers
Dan
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SCAR
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| posted on 5/7/13 at 11:23 AM |
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I still cant see why you would put grease nipples in when you can use the appropriate grease on assembly and it should last 40k miles (unless you go
rally cross which knackers polybushes through shock loads not wear) . Polyurethane is described as self lubricating that's why its used for
bushes.
How many road miles are you intending to do? average 5k a year and those nipples will come in handy in 8 years time although I don't know how
you will get silicone grease through the nipples anyway (it comes in 50g tubes)?
It seems to me that you would be putting in nipples that aren't needed to facilitate applying the wrong grease.
Only my opinion, of course, I am sure you should build what you are happy with.
[Edited on 5/7/13 by SCAR]
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MikeRJ
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| posted on 5/7/13 at 12:59 PM |
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quote:
Originally posted by SCAR
I still cant see why you would put grease nipples in when you can use the appropriate grease on assembly and it should last 40k miles
The grease doesn't tend to last 40k miles though, you're lucky if it lasts even 1k miles before the squeaking starts IME. It's not
really surprising either, since there is no clearance between the bush and the crush tube (a negative clearance in fact) so any lube gets squeezed out
by the normal action of the suspension.
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Bluemoon
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| posted on 5/7/13 at 01:31 PM |
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quote:
Originally posted by MikeRJ
quote:
Originally posted by SCAR
I still cant see why you would put grease nipples in when you can use the appropriate grease on assembly and it should last 40k miles
The grease doesn't tend to last 40k miles though, you're lucky if it lasts even 1k miles before the squeaking starts IME. It's not
really surprising either, since there is no clearance between the bush and the crush tube (a negative clearance in fact) so any lube gets squeezed out
by the normal action of the suspension.
I will probably rebuild with SS crush tubes first but from experience I doubt it will last long before drying out. My own opinion is most people do
only a few 100's dry miles a year (may be 1,000) and these problems just don't show up! There is a good reason why the large manufactures
use flexible rubber bushes, fail safe, cheap and no maintenance.
Cheers
Dan
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Slimy38
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| posted on 5/7/13 at 03:28 PM |
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I bought these;
http://www.ebay.co.uk/itm/181161852772
stainless inserts, and the pairs of top hat bushes have a gap in the middle that I was going to pack with grease. That gap is where I might expect a
nipple to be most effective, you'd basically refill the gap with grease when you start hearing mice.
At the very least they might do you a set of stainless inserts for a good price?
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atomic
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| posted on 8/7/13 at 08:16 PM |
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To aid in assembly/disassemble wrap your polyurethane bush/crush tube in PTFE tape as unlike grease it doesn't attract dirt, it also helps get
rid of the squeaking that can occur when using poly bushings. We've been doing this for years and use POLY-TEMP HD or XHD branded tape as
it's the best quality we could find.
[Edited on 8/7/13 by atomic]
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