DIY poly bushes

[budd]

It is possible, realistic to cast poly bushes at home?
I've been looking at various products to create a 95A shore replacement bush and this one see link from resins online looks like it may do the trick
http://www.resins-online.com/product...category_id=71
As anyone tried to cast their own bushes? any expreience on what product to use or whether it is veasible would be most welcome.

[Zico]

Personally I dont like Poly bushes, I had a few problems with my application in a semi independent trailing arm rear set-up where the adhesive bonding the dampers poly bushes to the inner metal tubes attached to the trailing arms disintigrated causing them not only to creak but to wear badly due to the rotation and develop play.. while the elasticity of the standard rubber bushes simply didn't allow this to happen.

I dont see any reason why you couldn't cast them, would probably take some trial and error and may not turn out to be very econimical unless your particular application isn't catered for by the various manufacturers.

See http://www.nsra.org.uk/newforum/showthread.php?t=18302

[budd]

Originally Posted by Zico

Personally I dont like Poly bushes, I had a few problems with my application in a semi independent trailing arm rear set-up where the adhesive bonding the dampers poly bushes to the inner metal tubes attached to the trailing arms disintigrated causing them not only to creak but to wear badly due to the rotation and develop play.. while the elasticity of the standard rubber bushes simply didn't allow this to happen.

I dont see any reason why you couldn't cast them, would probably take some trial and error and may not turn out to be very econimical unless your particular application isn't catered for by the various manufacturers.

See http://www.nsra.org.uk/newforum/showthread.php?t=18302

thanks for the response, I guess nothing is without problems and I agree in some applications rubber would be preferred and I think in all race applications rose joints are best solution to removing the slop in production car suspension.
I'm building a Impreza for the Subaru Cup which currently runs in the Nippon Challenge grid, the regs for my planned production class entry don’t allow spherical joints but does allow poly bushes, so I got thinking 2kg of resin woulf make a lot of bushes, so rather than it costing more it should be considerably cheaper than buying a set from a popular manufacturer who typically charge £300 plus for a full set.
The process will require a bit of trail and error but any failures can easily be re-done until it works (or I give it up as a bad job) the idea is to remove the stock bush clamp the arm to a flat surface (with release agent applied) mix the resin with the right amount of hardener to achieve close to 95A shore pour into the suspension where the OE bush once resided once cure it should be possible to drill it out and press in a inner sleeve and bob’s your uncle one poly bush, hopefully this is how it would work, although some experimentation may be required if the poly resin holds together the suspension will pivot on the steel insert and function exactly like a shop bought poly bush.

Thanks for the link, it seems the guys wants to machine his bushes for a preformed ‘rod ‘ of polyurethane, my idea (as suggested above) is to cast the poly direct into the suspension piece, it may prove impractical to drill the bush out after casting due to it’s elastic properties, in that case it would be necessary to include the inner sleeve at the time of casting.
Either way I don’t think it the problems will be insurmountable but I’m interested in anyone else’s experiences, the next stage will be to speak to the resin supplier and get there opinion.

[phoenix]

If you are planning to drill the bushes anyway, why not just machine them from solid bar and do away with the casting process?

http://www.bonaprene.co.uk/shop/13_P...hane_Tube__Rod

http://www.gcip.co.uk/EP/materials/nylatron.htm

http://www.davis-plastics.co.uk/acetal.html

[JamesH]

Originally Posted by phoenix

If you are planning to drill the bushes anyway, why not just machine them from solid bar and do away with the casting process?

http://www.bonaprene.co.uk/shop/13_P...hane_Tube__Rod

http://www.gcip.co.uk/EP/materials/nylatron.htm

http://www.davis-plastics.co.uk/acetal.html

What he said....

I've heard of people machining them, but not casting their own. (although that doesn't mean nobody does it!)

Although, can you not purchase bushes predone for that car? I'd check Rally Design.

[MGDavid]

Originally Posted by JamesH

......Although, can you not purchase bushes predone for that car? .......

quite possibly; then again perhaps not. I took it from the OP that it's something unusual. DIY polybushes were discussed on an MG forum a while back, needing to replace a bush that's NLA. IIRC we concluded it's do-able but I don't think anyone actually went through with it.
Cost would be another reason to have a go, a car set for my latest acquisition is 300 quid whereas if you could make them for say, 50 quid's-worth of material then that's another race entry....

[budd]

Originally Posted by JamesH

What he said....

I've heard of people machining them, but not casting their own. (although that doesn't mean nobody does it!)

Although, can you not purchase bushes predone for that car? I'd check Rally Design.

Originally Posted by MGDavid

quite possibly; then again perhaps not. I took it from the OP that it's something unusual. DIY polybushes were discussed on an MG forum a while back, needing to replace a bush that's NLA. IIRC we concluded it's do-able but I don't think anyone actually went through with it.
Cost would be another reason to have a go, a car set for my latest acquisition is 300 quid whereas if you could make them for say, 50 quid's-worth of material then that's another race entry....

Unfortunately I don’t have access to machining facilities, which I why I was thinking of casting insitu, plus the cost of buy pre formed rod would be prohibitive I may as well buy a set of dedicated bushes.
It may turn out that for various reason it’s not feasible to cast these, eg they may need to be pressure cast to avoid bubbles / imperfections etc but as stated a full set of bushes from powerflex / polybush et al cost in the region of £300 and looking at the stuff from resins online the cost of the basic resin is around £50 plus pigment so a total of £60 and some evenings in the garage over winter, and as quite rightly said the difference is a race entry or nearly 2 tyres, any money saved is a good thing in my book, however if it doesn’t work then it’s money wasted which isn’t good, but given the relatively small outlay it’s got to be worth serious look

[Dave Brand]

Originally Posted by budd

once cure it should be possible to drill it out and press in a inner sleeve and bob’s your uncle one poly bush,

Why not just cast it with the inner sleeve in situ? You would probably get more accurate location of the bush & possibly a better bond between the sleeve & the bush.

[budd]

Originally Posted by Dave Brand

Why not just cast it with the inner sleeve in situ? You would probably get more accurate location of the bush & possibly a better bond between the sleeve & the bush.

I considered this, but IIRC poly bushes generally come in 3 parts, 2x 'top hats' (the bush part) and the central sleeve, this sleeve pushes through when the bushes are in place, when tightened the bush will rotate on the sleeve, OE rubber bushes have enough 'flex' to allow for the suspension travel with a bonded in sleeve, a bonded in sleeve on a poly bush wouldn’t allow this flex and would cause stiction(?) and tear free possibly causing the bush to wear / disintegrate.
It shouldn’t be to difficult to accurately drill a 10-12mm hole through the centre of the bush, maybe even offset slightly to include geometry changes.

[JamesH]

Originally Posted by budd

I considered this, but IIRC poly bushes generally come in 3 parts, 2x 'top hats' (the bush part) and the central sleeve, this sleeve pushes through when the bushes are in place, when tightened the bush will rotate on the sleeve, OE rubber bushes have enough 'flex' to allow for the suspension travel with a bonded in sleeve, a bonded in sleeve on a poly bush wouldn’t allow this flex and would cause stiction(?) and tear free possibly causing the bush to wear / disintegrate.
It shouldn’t be to difficult to accurately drill a 10-12mm hole through the centre of the bush, maybe even offset slightly to include geometry changes.

You are right - the bush should rotate around the centre sleeve. Worth lubricating them as well - they do tend to rust, and need to be regularly dismantaled to keep them running smoothly as well.

Also, you may find the centre is very very stiff depending on how good the fit is. I've had some success with heating up the centre bush and pushing it through the top hats which in the suspension arm - this 'melts' a smooth straight path through the bushes. Need to do it a couple of times to get right through though. And use thick gloves and pliers!

[budd]

Originally Posted by JamesH

You are right - the bush should rotate around the centre sleeve. Worth lubricating them as well - they do tend to rust, and need to be regularly dismantaled to keep them running smoothly as well.

Also, you may find the centre is very very stiff depending on how good the fit is. I've had some success with heating up the centre bush and pushing it through the top hats which in the suspension arm - this 'melts' a smooth straight path through the bushes. Need to do it a couple of times to get right through though. And use thick gloves and pliers!

I think it's lithium grease that is used to lube them, good idea heating up the bush though.
I'm just waiting for a call from the tech people at resins online to see if it's feasible and what product they wouuld recommend.

[MGDavid]

I'd be very interested to hear how you get on - please keep us updated :-)

[JohnD]

Seen this?
No sound, but it looks as if he's making P/u bushes in a three part mould.

http://www.dailymotion.com/video/x2ml0f_moulage_tech

John

[phoenix]

Originally Posted by JohnD

Seen this?
No sound, but it looks as if he's making P/u bushes in a three part mould.

http://www.dailymotion.com/video/x2ml0f_moulage_tech

John

Hmmm.

You don't need much kit to save a quid or two on the final product then?

[Zico]

You should find these DIY cases links helpfull Budd.

http://forum.bmw5.co.uk/viewtopic.php?f=9&t=47577

http://forums.turbobricks.com/showthread.php?t=146478

[budd]

thanks for the links, interesting stuff, the BMW link very interesting in that he is just strengthening th OE rubber bush, so it got me thinking that if I drilled out / removed 90% of the rubber in the bush and then filled with Polyurethane it would produce a much stiffer version of the OE bush, the only problem is the flex required to allow suspension travel would be limited, so the retaining bolts would need to be losened to allow free movement, this should be a problem if they are all torqued to allow free movement with no free play, and the nuts retained with split pins / R clips/ lock wire etc to stop the nut coming off if the became 'to' loose.
At the moment I'm waiting for a response from the online supplier, to decide the appropriate product although the Ultracast 10 95A shore stuff looks perfect to me, but I'll take advice before buying.

[GORDON STREETER]

I have been looking at this thread from time to time, although I will give you credence for what you are trying to achieve I feel you are wasting your time and money on something that any machinist can make in 5 mins out of "off the shelf" materials. OK you "might" save yourself a few quid, but its not as if you will be making loads and certainly wont be cost effective (I know this doesn't matter in this case) Anyway I hope I'm proved wrong
Years ago my brother told me that he had though of a way of making "perpetual motion" with a gizmo he was making. I told him that it was impossible with the mechanical devise that he was making, however he carried on with it for months until I was proved right

[forestdweller]

Didn't the original poster say he was preparing an Impreza? It's a very common "tuner" car here in the States. Poly bushings are readily available and inexpensive.

http://www.allsuspensionbushings.com/17638.html

[MGDavid]

Originally Posted by forestdweller

Didn't the original poster say he was preparing an Impreza? It's a very common "tuner" car here in the States. Poly bushings are readily available and inexpensive.

http://www.allsuspensionbushings.com/17638.html

crazy fubar website, search doesn't work with firefox !

[phoenix]

Originally Posted by budd

the only problem is the flex required to allow suspension travel would be limited, so the retaining bolts would need to be losened to allow free movement, this should be a problem if they are all torqued to allow free movement with no free play

This sounds like a very bad - and dangerous - solution to me.

[budd]

Originally Posted by GORDON STREETER

I have been looking at this thread from time to time, although I will give you credence for what you are trying to achieve I feel you are wasting your time and money on something that any machinist can make in 5 mins out of "off the shelf" materials. OK you "might" save yourself a few quid, but its not as if you will be making loads and certainly wont be cost effective (I know this doesn't matter in this case) Anyway I hope I'm proved wrong
Years ago my brother told me that he had though of a way of making "perpetual motion" with a gizmo he was making. I told him that it was impossible with the mechanical devise that he was making, however he carried on with it for months until I was proved right

you may well be right, although casting poly bushes should be a damn sight easier than making a 'perpetual motion' machine LOL, but without people like your brother 'giving it a go' where would we be? it takes alot of trying and failing before a 'eureka' moment.

Originally Posted by forestdweller

Didn't the original poster say he was preparing an Impreza? It's a very common "tuner" car here in the States. Poly bushings are readily available and inexpensive.

http://www.allsuspensionbushings.com/17638.html

your quite right poly bushes are widely available and reletively inexpensive at around £300 a set, but I'm aiming to do the job for around £60 OK it's extra work but as someone said the difference in cost is the best part of a race entry, so it's got to be worth looking in to.

[budd]

Originally Posted by phoenix

This sounds like a very bad - and dangerous - solution to me.

it does doesn't it , leaving bolts intentionaly loose isn't the best idea and only shows that the central bushing must be free to rotate within the poly bush

[budd]

Originally Posted by forestdweller

Didn't the original poster say he was preparing an Impreza? It's a very common "tuner" car here in the States. Poly bushings are readily available and inexpensive.

http://www.allsuspensionbushings.com/17638.html

just checked this site out and their 'master' bushing kit and thought WOW a complete bush kit for under $150 that's great value but then had a look at the contents of the kit see below, not very comprehensive is it!!! free shipping though


Energy Suspension 19-18101G Energy Suspension
Product Line: Energy Suspension Hyperflex Bushing Kits
Part Type: Complete Bushing Kits
Part Number: 19-18101G
Bushing Material: Polyurethane
Bushing Color: Black
Front Control Arm Bushings Included: Yes
Rear Control Arm Bushings Included: No
Front Sway Bar Bushings Greaseable: No
Rear Sway Bar Bushings Included: Yes
Rear Sway Bar Bushings Greaseable: No
Front Sway Bar End Links Included: No
Rear Sway Bar End Links Included: No
Steering Rack Bushings Included: No
Body Mounts Included: No
Front Strut Rod Bushings Included: No