Polybushes 1500

[cleverusername]

After driving the 1500 my father thought it was bit too "rolly", he thought that some polybushes would be a good idea.

The shocks seem to be ok, they pass the bounce test. However I am a bit weary of polybushes having read some other posts here that complain it has made the car too harsh.

The consensus seems to be to use a combination of rubber bushes and ploybushes. So I wondered if anyone has any advice, about what would be best to use where when I get round to it.

[Jon Tilson]

Drag strut ends and rack mountings give a good return. I dont bother with too much esle.
Dont do the inner track control arm bush - stick with the OE rose joint.

Jonners

[Dolly-Nut]

I'd do the axle end of the rear tie bars and front drag struts first. The rest are usually okay.

[tinweevil]

I concur with the wise words above. Just to ensure no confusion poly 152588, never* poly 216903

Poly 152767, never poly ULC1580

Everything else is fine in rubber.

* Never except on a race/track day car where there's little to hit and people on hand to pull you out of the wreckage when you stop barrel rolling.

[Toledo Man]

Not all polyurethane bushes are created equal. Aren't the Super Flex ones equal to rubber? They're certainly the best quality ones.

[alangraham]

Follow all the advice on this forum. I ignored it at my cost and polybushed the whole of my 1500, no expense spared. It's now very harsh and drones, particularly from second to third gear and I used the recommended bushes. Yes it's tightened everything up but if I knew which bushes to replace with rubber again, I would.

[GlenM]

I believe that there are two types of rubber bush ULC 1580, a void one and a solid one.

Years ago a friend of mine tried (very badly) to re-shell his Sprint into a 1500 FWD drive shell. It was a total disaster and the back end used to steer when you came on and off the throttle. After he cooked the engine by fitting an 1850 radiator (I told him not to but he knew best), I broke the car for spares, and found that he had solid bushes on one trailing arm and the void type on the other.

[Jon Tilson]

I like the voided bush for better ride quality. Its fitted on mine to be stiff in lateral twist and softer vertically.
I would never fit poly bushes to the radius arms myself.

For a droney car I would be looking at the subframe mounts. I have poly on mine here too and its not
droney. I'd make sure you have it fitted correctly....the one between the subframe and body at the back
is the crucial one here.

Jonners

[sprint95m]

I concur with the wise words above. Just to ensure no confusion poly 152588, never* poly 216903

Poly 152767, never poly ULC1580

Everything else is fine in rubber.

* Never except on a race/track day car where there's little to hit and people on hand to pull you out of the wreckage when you stop barrel rolling.

Julian, to pick up on a couple of things if I may.....

The diagram showing the lower back trailing arm is incorrect because different bushes were fitted front and back.
It is possible to use the back (solid) bushes in place of the front (void) bushes, which will improve axle location.


The Superflex bush for the track control arm is a straight replacement for the rose joint but without the original's reliance on water shields.
Indeed, as Dave has pointed out, Superflex bushes are of the same shore as the rubber originals...hence their widespread use on road cars.
The other makes of polyurethane bushes are normally much harder because these are aimed primarily at motorsport applications.
(The Rally Design catalogue gives an explanation briefly detailing the differences.)



Personally I don't bother with using replacement bushes for the steering rack mountings, instead I opt for solid aluminium alloy,
simply because it is a fit once option.
As for the harshness or otherwise of the ride quality, our cars compare favourably to a standard (classic) Saab 900 or a noughties Fiesta or 5 series BMW.


A stainless steel "sports" exhaust will make any suspension or road noise inaudible in my experience.



Anyhow,
the point I wish to make clear is that not all polyurethane bushes are the same.




thanks,

Ian.

PS I have been using Superflex TCA bushes since 2008.
At that time I wrote a short article published in Dolly Mixture describing how dangerous the TCA bolts had become on my car (due to water ingress),
a problem that the Superflex design overcomes.

[Jon Tilson]

I have never found the tca bolts to be an issue as long as the water shields and rubber seals have been fitted correctly.
Eventually the rose joint just wears out IME and inner edge tyre wear is the issue.

It takes about 80k miles though...

The shield washers and runner seals are similar in design to spitfire trunion bushes. They seem to last reasonably well too.
Maybe you have just been unlucky Ian?

The crucial fitment point is not to tighten the tca bolt until the car is on its wheels in the resting position, as with all other
metalastic style bushes.

Jonners

[tinweevil]

I agree with you on most points Ian, not least that the image I used for the rear is incorrect. I agree that the waterseals are not ideal. I cannot agree with you on two issues though:

1) Why was it unnecessary for Triumph to go to the additional expense of using a rose joint at the TCA? They could have used rubber and had several shore grades in common use at the time but opted for additional free movement.
2) Why was it unnecessary for triumph to go to the additional expense of using a voided bush for the front of the trailing arm? They could as you suggest used the rear bush at the front but opted instead to use a different design that gave different resistance to rotational vs other load directions.

In both these cases the designers stamped their feet hard enough to get the expense past the beancounters. That speaks volumes to me. So Ian, how precisely were Triumph incorrect? Bear in mind that any answer along the lines of 'It'll be fine because <insert manufacturer/reseller trying to flog their product> say so' will just get laughed at. Science please.

[cleverusername]

Thanks for the replies, I seem to have started quite a debate.

I will take the above advice, and go for minimum changes first. I don't like harsh rides, modern cars are awful in this reguard. So much money spent on sound proofing, and ergonomics, runined so it can put on a decent show on a track for some road tester.

Just want to tightened it up enough that I can feel confident overtaking on the ring road.

[sprint95m]

Thanks Julian, I can hopefully satisfactorily answer your first point but can only give further questions to the second:

Point One.
I didn't say it was unnecessary to use a rose joint, only that its reliance on water shields is its weakness.
Over the years I have completely stripped three front suspensions....a Sprint with 33,000 miles, a Dolomite 1300 and my current 1850 (50,000 miles)
and all had varying degrees of corrosion to the bolts. The 1850 was worst as one bolt had seized resulting in the pickup holes being worn oval (I fitted new uprights).
Hence why it is the water shields that I don't like.

The problem with rubber bushes is that said rubber is bonded to the steel centre, therefore on a Dolomite suspension the rubber has to work very hard
resulting in a short lifespan (and of course associated deterioration of other components and the road holding of the car.)
Superflex bushes replicate the operation of the RJ rather than a rubber bush (the Superflex bush moves around its fixed stainless steel centre),
hence my comment about their suitability as an alternative.
(That is also the case for Superflex bushes intended for MacPhersion strut TCA bushes where originally rubber, eg T2000, Cortina, Capri....)


Point 2. Are voided bushes really significantly more expensive to make? I am thinking I disagree that they are, given the volumes we are talking about?
(What is curious is why use two when one could suffice....you could use the voided bushes at the back.)
(Also, the bushes used to retail for the same price so I don't know if price would have come into the decision at the design stage? Whatever, the retail prices
are irrelevant to the question.)
When they were testing prototypes did they try all solid bushes (or all voided)? With 155 tyres on rather narrow rims I am thinking that any differences
in suspension setups are harder to determine?
Using voided bushes was common to other manufacturers too.
These bushes are fine but do however have a rather short lifespan. (I know someone who fitted them annually to a Cortina after the summer caravan holiday.)



On a more general theme....
Even though technologies have moved on since the 60s and 70s,
the main problem we have with certain remade parts is that they aren't as good as the original versions.
I have experimented with some alternative parts from other makes. This is not because I am necessarily dismissive of the original designs
but because I am looking for viable alternatives, which hopefully means resources can be directed into remaking quality parts where we have no alternative.
(On a personal level I will use remade or alternative parts rather than originals because I prefer that said originals be fitted on restorations.)

Many things are better nowadays, eg tyres, hoses, hose clips, oils, coolants, headlamps, radiators, wiper blades, switches, etc,etc.
Some things are not as good brake pads, adhesives, fishing tackle.





Ian.