Uprated Wishbone Bushes

Noddie

Noddie

Hi guys,
As some of you may know iv been working on some uprated wishbone bushes for the K11.

I have sent a set to @frank for testing and he seems happy with them.
So I have designs which I'm happy with but I'm struggling with getting the correct stiffness. I wanted to offer two different ratings; one mild (most people seem to call it 'fast road') and one stiff option for track and under 25's (no back pain yet).

Im happy with my version of 'fast road' stiffness, they are Shore A-85 which falls somewhere between StrongFlex's red and yellow rating ( -LINK- to their info). Gotta say, frank didnt see much difference between the A-85 and stock bushes when he levered the wishbone with a crowbar.

The problem I have come up against is sourcing stiffer polyurethane, I have found a supply but its VERY stiff, it will be almost solid (something like nylon).

So what I would like your input on is whether you would consider buying the fast road bushes? and whether solid bushes would be appealing? Honesty as always please :)

They will end up somewhere in the region of £35 for both sides possibly slightly more for the very stiff option).
Pic of them (different colours will be for different stiffness ratings):
wishbone bushes (Small).jpg
 
yep on mine one time after oulton park with the turbo n pulsar brakes the old weak bushes were shredded by the intense force of the pulsar brakes and steering was darting all over on the way back home.
upgrading to PU bushes never happened ever again after several trackdays in the turbo:cool:
 
@Enuo
The bushes I have made are designed to fit without removal of the metal sleeve so burn out the rubber and fit new poly. pretty dam easy! I think the hard part could be the bolt for the front bush but frank seems to have worked out a pretty easy way for that even.

Its the stiffness I need feedback on really. Would people consider solid bushes?
 
Noddie said:
@Enuo
The bushes I have made are designed to fit without removal of the metal sleeve so burn out the rubber and fit new poly. pretty dam easy! I think the hard part could be the bolt for the front bush but frank seems to have worked out a pretty easy way for that even.

Its the stiffness I need feedback on really. Would people consider solid bushes?
Click to expand...
I would, I'm bot planning on running stretch so I have a sensible sidewall to take most of tghe abuse ;)
 
Noddie said:
@Enuo
The bushes I have made are designed to fit without removal of the metal sleeve so burn out the rubber and fit new poly. pretty dam easy! I think the hard part could be the bolt for the front bush but frank seems to have worked out a pretty easy way for that even.

Its the stiffness I need feedback on really. Would people consider solid bushes?
Click to expand...
either burn of drill the rubber out eh, and if you use a brand new blade, a snap-off stanley knife cuts any remains of rubber out no probs :)
and yes i had to cut the head off one of the bolts on my red car, the drove a wedge in between to ease the thread out, the 2 bolts on the white car had,nt seized :)

P2030479.JPG
 
Enuo said:
I would, I'm bot planning on running stretch so I have a sensible sidewall to take most of tghe abuse ;)
Click to expand...
i would definately go for solid ones for a track car (and a daily d too, if i was younger :D) i would say these yellow ones are about 50% stiffer than new factory ones (and 100% stiffer than the 17 year old ones that were removed)
 
frank said:
i would definately go for solid ones for a track car (and a daily d too, if i was younger :D) i would say these yellow ones are about 50% stiffer than new factory ones (and 100% stiffer than the 17 year old ones that were removed)
Click to expand...
Well since the council reduced the speed limit on the A38 (road to my work) from 30 to 20 I don't have to worry too much about comfort on my daily commute, never going fast enough to be uncomfortable ;)
 
OnlyA1.0 said:
I'd be interested in some of the fast road ones if youre deciding to go ahead with making this
Click to expand...
No problem Matt. Iv got everything I need to make those. There are a couple of types of wishbone so will need to know which you have. If you email me or send a message through the nodspeed website site (link in my signature) we can sort it :)
 
So it turns out the OEM wishbone bushes are less stiff than at first thought. I borrowed the durometer at uni to check and it turns out they are around a Shore A60 (brand new).
The polyurethanes I have been using are A70 and A85 so 15% and 40% stiffer :) So I will be sticking with these options :)

I will also be looking into solid bushes but they pose other problems (bearing surface wear mostly but also the need for exact fitment) so may be a little while.
 
frank said:
handling benefits alex, when you accelerate the bushes flex forward, and when you brake the bushes flex backwards.
and this effects the caster, toe-in, toe-out and stagger :)
Click to expand...

Ahhh gotcha, keeps the setup/handling more constant... May have to look at getting some then
 
the PU is stiffer, less give than rubber and is not bonded to the metal insert so:
- forces are transmitted to the chassis faster = faster response
- more % of the vibrations are transferred to the chassis rather than being absorbed by the rubber = more feedback sensation
- less deflection = more consistant arm position = consistent suspension geometry/alignment & handling
- bush can spin freely around the metal insert without twisting itself apart
- able to withstand higher forces for longer periods = durable

here's some cheap stock weak rubbery front bushes after afew trackdays with the turbo and pulsar brakes

30722669.jpg
38704314.jpg
scaled.php


and upgraded to these with no prob at all since

dsc06107-jpg.27735


http://micra.org.uk/threads/pollymobiles-rebuild.35251/page-50#post-509593
 
I have aluminium front bushes and nylon rear. You can tell the difference from the solid ones and normal rubber bushes

Although expect balljoints to suffer from increased vibration
 
Madmonkee said:
Yarp, might have a set of these :) probs buy new wishbones to start with. Whats the two different types?

Sent from my GT-I9505 using Tapatalk
Click to expand...
If im honest, Im not sure I completely understand them either.
Im trying to collect as many pictures and car details as possible to see if there is a pattern.
New wishbones and later models seem to be what I call 'size A' with a 32mm long bush housing with second inner sleeve (which PollyP cut out but should not be removed with my poly bushes).
It seems that the 'size B' are possibly tapered (not deformation as stated above).
I need more data really. Gotta take orders on a case by case at the moment and ask everyone for lots of pictures so I can work out what they have. ~
If you do get new wishbones, I got THESE which have served their purpose and I can guarantee they are sizeA
 
UPDATE:
Iv decided not to offer the 15% stiffer bushes. If someone really wants them I will sort it out but Id like to concentrate on performance upgrades.
So 40% stiffer is now 'Fast Road' and solid is now 'Track' :)
Solid bushes currently only available in Size A due to the need for a perfect fit and the odd shape of Size B.
 
So I tested a wishbone today for longitudinal strength (simulating breaking force or in extremes hitting a rock).

It failed with a maximum load of 13.5KN, but yield was around 10kN so thats the limit really.

This is the load extension graph. x axis is 0-50mm extension and y axis is 0-20KN
wishbone load_extension.JPG
 
Last edited:
Noddie said:
ha.
not really, it pull the wishbone down and measures the force needed to do so.
The wires are for separate strain gauges which will measure strain at particular spots.
Click to expand...
Forgive me if I've missed this bit.

So your testing to find a weak point... strengthen.. repeat?
 
Noddie said:
Create cad model. Perform physical tests to validate cad model then use cad model to improve design. Then manufacture improved design and test. :)
Click to expand...
Ah I see :) good stuff
The only thing I'd say is... start a fresh... the standard design is poo :p
 
Noddie said:
Any reason you consider it bad other than strength?
Click to expand...
Well the ones I had to replace weren't bent, they cracked.
On the back of that crescent shape where the front bush is joined... it cracked there. Didn't get too far but that was only a 60/70mph impact (it'd help if I saw the rock :p)
 
i,ve had to jig the chassis outrigger that hangs down on a few crashed k11,s ed (where the front of the wishbone bolts to) so the wishbone may be designed to collapse in a controlled fashion ?
 
Cracking sounds like fatigue failure, were they old?

The problem with making new ones is the cost. As part of the project I have designed some chromoly tubular ones, but I would have to charge lots for them and in my project I have stated that the target market is young rally drivers/teams who spend up to 5K on their setup, they arnt going to want to spend £500(guess) on the wishbones when they could get some strengthened ones for £150(also a guess).

For a one off, yes, tubular is the best bet, but not for a 'product' design imo
 
frank said:
i,ve had to jig the chassis outrigger that hangs down on a few crashed k11,s ed (where the front of the wishbone bolts to) so the wishbone may be designed to collapse in a controlled fashion ?
Click to expand...
This is also a concern, I will be looking in to this as part of the project as I am bound to get asked that question in the presentation. Any pictures of the bent chassis legs by any chance??? :)
 
Noddie said:
This is also a concern, I will be looking in to this as part of the project as I am bound to get asked that question in the presentation. Any pictures of the bent chassis legs by any chance??? :)
Click to expand...
this was when i was panelbeating in the 80,/90.s ed :) they were stretched outwards and had to be pulled back into position, you might want to also market a brace that holds the 2 outriggers in place/together :)
 
Noddie said:
Cracking sounds like fatigue failure, were they old?

The problem with making new ones is the cost. As part of the project I have designed some chromoly tubular ones, but I would have to charge lots for them and in my project I have stated that the target market is young rally drivers/teams who spend up to 5K on their setup, they arnt going to want to spend £500(guess) on the wishbones when they could get some strengthened ones for £150(also a guess).

For a one off, yes, tubular is the best bet, but not for a 'product' design imo
Click to expand...
They weren't new but they weren't old approx 6 months at most.

The ones I've made have cost less than £20 minus rose joints (just a fancy extra) and if rally is your target market strength is key over weight. Any rally crew with an ounce of sense puts a lot of thought into armouring the underside

Honest opinion uprated wishbones are not necessary on the junior tarmac cars at all as there's nothing to hit.. you're targeting forest cars if rocks etc are involved. Whose budgets are alot higher :)
 
h701micra said:
They weren't new but they weren't old approx 6 months at most.

The ones I've made have cost less than £20 minus rose joints (just a fancy extra) and if rally is your target market strength is key over weight. Any rally crew with an ounce of sense puts a lot of thought into armouring the underside

Honest opinion uprated wishbones are not necessary on the junior tarmac cars at all as there's nothing to hit.. you're targeting forest cars if rocks etc are involved. Whose budgets are alot higher :)
Click to expand...

Not all tarmac events are smooth, ex raf bases can be very tough with humps
 
If im honest, the actual product side of the project was slightly fictitious, its more for the grade really. I would like to make a good design but if its not a viable product it doesnt really matter (I just have to persuade the examiners that it is).
 
As far as the collabsible aspect goes, am pretty sure it was the fact that my wishbone snapped almost clean in 2 that saved the white car when I crashed it, meant the new wishbone bolted straight on :) Mk4 and 5 fiesta wishbones are made from a single sheet of pressed steel and thats a much more modern car so having wimpy wishbones must be slightly deliberate, if disconcerting!
 

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