Koni's aren't what they used to be

[mikew]

Driving back from Canley Classics today (no connection with this event), and there was a "bang" from the rear of the car, followed by clonks and funny handling.

This is what I found



This was only purchased 3 years ago, and has obviously had a stress crack for some time, and was finally finished off by the current state of our roads. Still worrying why it had partially fractured before and then rusted in the crack.

mike

[StagNL]

Just curious, what were the bushes made of?  Standard rubber or polyurethane?

[mikew]

699 wrote:

Just curious, what were the bushes made of?  Standard rubber or polyurethane?

I fitted the standard bushes that came with the koni's, and they weren't over tight.

mike

[piman]

Hell Mike,

any chance that the stud had grounded at some point and bent causing the original crack?

Alec

[mikew]

piman wrote:

Hell Mike,

any chance that the stud had grounded at some point and bent causing the original crack?

Alec

I don't think so, I have never had to straighten the stud, and it was straight 2 weeks ago when I dropped the diff out and replaced the quill shaft bearings. Oh the joys of old triumph cars!

mike

[StagNL]

mikew wrote:

I fitted the standard bushes that came with the koni's, and they weren't over tight.

mike

I'm guessing the standard Koni bushes are a rubber rather than the harder poly?  I've been told that poly shouldn't be used on the shocks as they can't take the constant hammering that rubber can.

Julian

[mikew]

699 wrote:

I'm guessing the standard Koni bushes are a rubber rather than the harder poly?  I've been told that poly shouldn't be used on the shocks as they can't take the constant hammering that rubber can.

Julian

Yes the Koni bushes are rubber. I suspect part of the problem is that the bushes need compliance to allow for the angle change as the trailing arm swings through an arc, so the lower fixing needs to allow for the angle between the damper and the arm changing. Modern cars do this via a horizontal bolt (which allows the damper angle to change) but triumph have a flat face fixing so the angle change must be compensated for in the bush. Some TRs have recently been suffering with the trailing arm fracturing on the damper mount, presumably for a similar reason.

I had a look on the Stag forum tonight, and there have been some other recent incidences of rear damper failure at this point.

so, is it the roads, poor parts, or changes in the damper bush?

mike

[piman]

Hello Mike,

the lower fixing is not the best idea, as you point out. I forget how old my Konis are but eight to ten years at a guess. I forget if the bushes are steel sleeved which would give a set compression to the bushes?

Alec

[mikew]

piman wrote:

Hello Mike,

the lower fixing is not the best idea, as you point out. I forget how old my Konis are but eight to ten years at a guess. I forget if the bushes are steel sleeved which would give a set compression to the bushes?

Alec

Alec,

there are no steel sleeves, they are the same mounting as a 2000. I have a coil over kit at the rear of my 5, which has a modified lower mounting with a horizontal bolt to cope with the arc change.

mike

[CRAJ]

I have poly bushes on the rear shocks on my pi, they were sold to me by Chris Witor who I have never heard of, recommending something that wasn't a good idea on the big saloons.
They are the softest type (blue) and it has always been my understanding that these are not a lot harder than the standard rubber bushes, but far more resistant to degredation!

Colin.

[mikew]

CRAJ wrote:

I have poly bushes on the rear shocks on my pi, they were sold to me by Chris Witor who I have never heard of, recommending something that wasn't a good idea on the big saloons.
They are the softest type (blue) and it has always been my understanding that these are not a lot harder than the standard rubber bushes, but far more resistant to degredation!

Colin.

I had the standard Koni rubber bushes, I wonder if I over compressed them, but looking at the otherside I don't think so.

I am just going to put it down to the poor state of our roads.

mike