Suspension bushings

["Bob Layman"]

I still am hoping for an answer to my original question on suspension
bushings (exhaust manifold portion was answered). Help please>
*****************
I would appreciate seeing (hearing) the opinions of those who have
replaced rubber suspension bushings with plastic. What brand, material,
price, and observations as to differences in ride, handling, and noise?
Were there any fitting or other problems (e.g., longevity)?
*********************

TIA,
Bob Layman (located in USA)

[Lincoln62]

Bob, as you didn't get a response I thought I would give you my $0.02.
I tried Nolothane bushes in the front suspension of my Mini many years
ago and they were so clunky and harsh I had to take them out. They
rattle your teeth. They would be great for racing as they give good
suspension location but I wouldn't have them in a road car. The Elan
may be different but I doubt it. I love the feel of the car as
standard, skinny tyres, donuts and all.

Peter
66S2

Bob Layman wrote:

["e s"]

Ditto,

if the car feels squirrely it may need new bushings, or likely struts, but plastic is useless in a street car.

[lotuselan2]

Peter

Rattle your teeth? My race Super 7 had BRONZE bushings in the front and
Teflon in the rear. Rubber? What's that?



Ken

'69 Lotus Elan +2 with BDR

[Lincoln62]

Ken

It's agreed then, nolothane is for sissies (along with springs and shock
absorbers). I think the key word is race, I'd like to see you driving
that baby on our bumpy Aussie roads.

Cheers
Peter

[steveww]

My S4 has poly bushes from Mick Miller fitted all round. As this was
done by the DPO I can not comment on a before and after. However I do
not find the ride harsh even on the UK's infamous B raods. The car feels
very planted and direct and goes round corners on rails. Had many
moderns screeching tyres behind me trying to keep up

Regards,

Steve Waterworth
***@***.***

Einstein: "The faster you drive, the slower you age..."

[twincamracing]

Hi Bob, I've used a variety of brands of poly bushes in a variety of
autos over the years. I tend to use them in sway bar, watts links and
control rods where the lower compliance than std improves handling. I
also use them in steering rack mounts and trans mounts.

I think about application before installing in components with a great
deal of rotation, like street car A arms, as the poly is not elastic in
rotation. Something has to move as the arm pivots. This is why poly
kits come with a grease (not just to ease assy), when the lube is gone
they tend to squeek like a rusty hinge and don't have a means of
lubrication without disassembly.

When the poly bushing is dry it tends to stick or bind until enough
force is generated to make it slip. As the resistance isn't linear it
can lead to odd handling.

Oh, with any suspension bushing installation put the car back on the
ground, and roll it and bounce it until it settles to its normal ride
height before tightening as the bushings are then in a neutral
position, that is without any rotational preload which will alter
corner weights and ride height.

Cheers,
Scott



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[s2lola]

Is Delron a feasible material in this application???

Cheers,
Bill Tebbutt

["e s"]

Delrin is fine; if you like breaking things.

What tires do yo have?

145, 155 80 13 ?

Try this, grab the top of the tire and pull it back and forth really hard, sideways. My guess is you get 2 inches of sidewall flex. When you can get rid of that, start worrying about solid bushings

[s2lola]

Not advocating Delrin, just asking. A friend of mine uses it in a few cars
because he says it has better self-lubricating qualities than poly.

My preference would be to use stock, factory rubber bushings on everything,
as I don't think that I can get to 90% of the car's handing capabilities (on
the street, anyhow) terribly often.

BT

["Bob Layman"]

Thanks for the responses so far. Apparently, I didn't give enough
info. The car, a 1970 S4 is being built for SCCA Solo 2 events in
the A-Street Prepared class (I believe the UK equivalent of Solo 2 is
a Sprint, but I am not sure). I am not worried about the compliance
of standard bushings as much as their likely non-linear contribution
to effective spring rate.

Compliance, however is a concern as the car will run on 13x8 wheels
and Kumho or Hoosier R-compound tires (near race slicks). The
clearance to the bolts for the rear lower outer bushings will be
minimal so longitudinal compliance here could be an issue.

As to being competitive against the primary competition of Z06
Corvettes and GT2/3 Porsches, it won't be unless I outdrive them
(likely for most but not all). Primary problems are: 1) intake
manifold is free for all except those with an integrally cast intake
manifold (read Lotus twin cam), 2) I'm not allowed to swop the damn
doughnuts out for CV halfshafts, and 3) Elan suspension geometry was
designed for 1960 era tires, not today's excellent tires.

Primary advantage of the Elan is it is quite narrow so tight courses
are less tight to the Lotus compared to the very wide Z06 and
Porsches. The other advantage to me is the Elan, since I already
have one, is easier on my wallet. If money were not an issue, I
probably would just buy a new Elise and have an easier time of it.

Bob

[lotuselan2]

Bob

Considering your purpose and the big tires, I would go for very
non-compliant bushes. Back in my Super 7 racing days I was able to legally
run Formula Super V front tires all around. At that time they were a
cantilever design with a big bulge out from the rims (7+ inches of slick
tread on a 5 1/2" wheel). I modified the rear trailing arms and sway bar
with a bow in them to clear the tires. As for the bushings, I used
glass-filled Teflon bushings. The good lubricating properties of Teflon
five low resistance to normal suspension travel. One thing that is good
with a Teflon or other machined busing is that you can have the hole drilled
as an eccentric. This than gives you some suspension adjustment. Back in
the '70's that was the only legal way to adjust front camber on the 7 (must
guys cut off the lower suspension ears and welded on a new ones with the
hole where they wanted it). I did have oilite bronze bushings in the front
but I would not recommend them. Buying the Teflon is easy via a plastics
distributor. You buy it in round rods and pay by the pound. Be sure to get
the glass-filled Teflon it is much more durable. Any machine shop can cut
them to size. Be sure the make at least two sets, they will wallow out in
time.



Ken

'69 Lotus Elan +2 with BDR

["Bob Layman"]

Ken,

Thanks for the info, it is what I was looking for. A few further
questions, however.

Did you have each bushing machined as a one-piece hat for each
location, i.e., four "round hats" for the lower rear inners, or
eight "round hats" with each inner rear requiring two bushings to
complete the assembly? Either way, what was the logic (which
presumably would apply to the front inners)? I have seen a picture
of a solution where the bushings were merely a round section not a
hat section, but this logic escapes me as it would require washers to
bear on the suspension arms which defeats the quest for low friction.

For the rear outers, the one piece solution with hats toward the hub
carrier seems the only feasible solution from a packaging (wheel
clearance) perspective.

Thanks,
Bob

[twincamracing]

might be easier to get bushes of the proper size than buy stock and
have it machined...plastic has dimensional changes when machining, when
the finished part is done it will move as it cools.

suppliers like powerflex usually have dimensional stock available in
straight and top hat style or someone like
http://www.buntingbearings.com/

cheers,
scott




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[twincamracing]

Hi Bob, you might also be able to source proper sized od bushes with a
larger id, reducing the amount of rubber, and simply sleeving the id to
the right size.
Scott





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