What are the bushes made from?
 

Is there different types of polyurethane? We have some at work and I'm considering using it to make the wishbone bushes but want to make sure its the right stuff.

all i know is that the bushes have to be flexible & not too hard so that you dont get too much stress on the welds but i´d also like to know exactly what kind they´re made of because i´ll also be making them myself at work.
cheers

Poly bushes !!
 

Polyurethane is sold by it's shore rating

80 or 90 shore should be ok.

I have heard it said that this material can be difficult to machine.

One thing I would say, my Poly bushes were definately injection moulded. ;)

Personally, I would not know as I have never tried to turn the stuff :)

Heres a linky to the correct grade

Polyurethane Bar

It has been mentioned that freezing makes it easier to machine.
It is very expensive and is it worth the effort when they can be purchased with the sleeves for about £90.
I am making my own and used UHMWPE,total cost about £30,including sleeves.

Hi, ive made my bushes from black delrin its probably harder than the poly bushes but i figured if some people use rose joints then a slightly harder bush should be ok

Quite happy if anyone wants to give me a valid reason why not.

I paid £15 for 1metre of delrin and £3.50 for the four 300mm peices of 19mm stainless from the scrappy

I have my own lathe so making them was easy for me (engineer 28yrs)
Ray:)

There is no valid reason "why not" ,we are building on a budget and you get the I made this factor as well.

the reason not to use hard bushes is that there are alot of forces in all directions on the suspension so not only up & down but also forward & backwards & so if the bushes are too hard all that stress & force will go to the welds .
Cheers

raylee what speed do you turn them at i allso want to turn my own.
thwang

question to flyerncle re bush material.
 

Hi there,
reading your reply on the bush material subject and would like to know what the UHMWPE material stands for and is it as good as poly bushes.
cheers
tony

Here you go Tony

A Bit of info & online shop

I must admit, I had to find out when I read that :D :D

can you use neoprene instead?

Cheers Ronnie,saved me trying to remember/work it out.

Neoprene is soft so possibly not good for bushes.
With regard to using hard bushes I understand your concern that passing more forces to the weld/structure may cause failure, but on the other hand what about the use of Rose joints as they are more or less solid.
Personal opinion on bushes, I have used the best/cheapest/easiest solution to the problem and it will do what I need it to do.
A certain amount of give in the bushes will lessen feedback from the road ie bumps and the like as this will not be fed back through steering and suspension, I think I have read that poly bushes are abrasive and the stainless tubes were sacrifical/meant to wear, so I suppose it all depends on what you want from the car and how much time and money you want to spend.
Please do not take any of the above as argumenative it's only my point of view and there will be someone on here who can give the definitive solution.


Cheers All

UHMWPE = Ultra High Molecular Weight PolyEthylene

Neoprene is more than likely far far too soft for bushes - although the only neoprene I have dealt with is in Diving kit. (as an aside - neoprene is generally made by injecting nitrogen into rubber sheets)

To Flyerncle - I assume that it is only the SS tube that is meant to rotate inside the bush. Otherwise given (a lot) of time surely the outer wishbone bush tube would also wear??

I personally think, that in terms of wear, the mileage we do is probably inconsequential. A lot of rep-mobiles are doing 50k a year, how many roadsters are doing more than 10k??

Again, not trying to start a ruck, just furthering my learning:D

Sean

Sean,If you look at how the suspension is set up the tube is clamped in the bracket and the bush turns on it, if fitted correctly the bush should not rotate in the sleeve of the wishbone and that would defeat the object of the poly bush as it is meant to rotate around the stainless tube.

You are dead right about the mileage and wear and tear thing as in reallity the car will do very little in terms of road use and most suspension bushes are rubber with a sleeve moulded in to it.

That would be why the sleeves are a tiny touch longer then:rolleyes:

This is turning out to be quite interesting. The neoprene we use at work is very tough. Its used to hold sharp steel panels in pallets, For rollers on heavy pallets and as spacers on welding arms (welders used constantly for approx 16 hrs a day). I will find out the spec of the material and compare with the polyurethane

I must say, I never imagined neoprene could be quite so tough, but then again, look at the info Dupont has on it, specifically for car use - Neoprene info for cars

Material science is crazy

Sean

Just to complicate matters further, factor this into the equasion,every rubber compound has "hysteresis"(possibly spelt wrong)basicly the amount of bounce/rebound it has.
So if you use something that is not hard enough you will end up with soggy feeling suspension/steering.

Possibly so Sean;)

Bring back Metalastic bushes

Nice soft ride ;)

Suit my old stiff bones :o :o

On a serious note. If when my build is completed & I find the ride a bit harsh, i'll certainly look into Metalastc bushes as an option. :)

i having my bushes turned out of uhmwpe, not sure if this will be to stiff, but gonna try it and see how it goes.

Thought about it too Ronnie,but finding the right size is a pain.

after reading this i fancy having a go at turning my own bushes i plan to make as much of this car as possible

ive got a small variable speed penmaking lathe from axminster
whats the material to use then? where can i get it from
what tools should i use and what speed


thanks Andy

Plastics direct,Delrin,Nylon 66,UHMWPE, Sharp tools and not too fast or the plastic will melt.

Good Luck.

cool thanks for that
nylon 66 is very cheap half a metre of 32mm £12 should be more than enough
just need to find the steel tubes now

Andy

If you are making the bushes - make the tubes

19mm round bar (stainless or mild steel, with SS being preferred ) centre drilled on the lathe to 12mm

Cut to length, and put a chamfer on the end to aid squeezing into the bushes

hmmm getting technical now lol

whats this oilon rod im looking at it looks very tempting

Andy

Which bit of that was technical:confused:

Oilon is basically an oil (lubricant) impregnated nylon.

It is well used for bearings, but not necessarily bushes, which also have to absorb shocks.

A few on here are using 'rigid' plastics for their bushes. I have to admit to buying a set of PU bushes complete with tubes when my lathe was up the spout.

Nothing to do with the horrible stringy mess turning nylon seemed to make:D

the drilling out the centre of the 19mm stainless iv never done anything like that before
ive made pens out of very hard acrylic before have to get them down to half a mm thick too! so the bushes shouldnt be a problem

Andy

ok, what I have learned so far, from advice, books, tinterweb and advice, on drilling centrally.....

Get the work as centred in the chuck as you can - use a dti
Take light facing cuts on the end until you have a flat face
use a centre drill to bore a pilot hole (centre drills have a very thick shaft - bit like this - )
Start with a smallish drill, then work up in a couple of steps to just under finished size (say 11 or 11.5mm) use a 12mm drill to finish off
Use plenty of cutting fluid (I think I used 3mm 7mm 11mm then 12mm when doing parts for the rear uprights)

Stainless always seems harder to work than mild steel to me

Using progressively bigger drill bits gives the lathe an easier time.

Hope this helps

As for cutting speeds:
On the mini lathe - I used what sounded/felt right
On the myford - RPM is on slowest, feed is on finest - I just vary the depth of cut:D

Stainless is a dog to drill, I got some scrap rod and tried it and just burned drill after drill even with cutting fliuid/oil, steel is much easier and given the mileage the car will do does it really matter.

The problem with stainless is that it has a work hardened surface that you need to get under, if you let the drill run slow, this will work harden the material and the drill will burn out. What you need to do is have a sharp drill and don't be affraid to push it. Oh and use plenty of coolant ;)

Kind regards

John

I must just be unlucky John,I had the lathe running fairly fast and was not frightened to push the drill hard but no luck, it was scrap studding so who knows what it was but it is hard stuff.

Cobalt is your friend:D

But your wallet will hate him:rolleyes:

Bloody expensive drills Sean...

I know:rolleyes:

Better if you buy a set, but mine were still £50+ for 1-13mm in 0.5mm steps

Still, they only come out the box for tough stuff:D

I actually have a set of HSS, plus a set of Titanium coated (nicer on ally) as well.

Different tools for different jobs.

we work almost only with stainless & have never had any problem drilling ,however it can happen that the drill wasnt sharp or wrong speed & the drill can burn & then what happens is that alot of the drill matirial stays in the hole & makes the steel immpossible to brill (so the inside of the hole can get as hard as the drill itself when it burns).
cheers

Made them from steel bar in the end,easy to machine and for the use they will get, probably last a lifetime.:D