MikeV8SE

New Member
Here's the situation - I recently fitted a set of Insa Turbo Traction Tracks (235/70/16) and from 60mph upwards there's a really loud/intrusive rumbling noise in the cab, combined with some equally bad and intrusive vibrations. This was not apparent with the original tyres.

I had the tyre pressures checked (28/34Psi F/R), refilled the tyres with Nitrogen to keep the temperatures more constant and checked the wheel bearings - all OK.

I kind of put it down to the fact that they're a fairly chunky remould tyre, although not happy about it, but wasn't sure what else to do.

However, my mate has just had a set of the same tyres (235/85/16) fitted to his standard Discovery 1 (basically the same car underneath) - and guess what, none of the loud rumbling or bad vibrations at motorway speeds!

So, what the hell is going on? Could it be defective tyres? Or something wrong with the car that wasn't showing up with the original 205 wide tyres?

Please help, I need to get this sorted!!
 
First test is swap wheels/tyres with the Disco and compare the results. You know they are good on the Disco so this will rule out vehicle difference. Are they directional because a directional tyre going the wrong way howls like a banshee.
 
When I replaced the tired springs and shocks on my classic with new one's it introduced heavy vibrations, I traced it to the swivel preloads, adjusted these and have had no trouble since.

Probably not the same as your vibration because it used to kick in at speed when you hit an uneven bit of road and wasn't there all the time. But it was certainly the much tighter springs and shocks replacing the saggy old one's that high lighted the problem with the swivel preload.

Your new tyres with lots of tred have probably done something similar and exposed a weakness in the suspension. Be it shocks, bushes, tie rod ends etc, etc. The trouble is finding which component.

If it was me I'd bite the bullet and go back to a less aggressive tyre. Which I know means taking a hit in the wallet but at least you would have a smooth ride.
 
Might be worth replacing the panhard rod bushes. usually transforms the handling of a RRC
 
First test is swap wheels/tyres with the Disco and compare the results. You know they are good on the Disco so this will rule out vehicle difference.

Yep, that's was what I was thinking, good call! Just don't have any axle stands to leave the Disco on, will have to go buy some.

When I replaced the tired springs and shocks on my classic with new one's it introduced heavy vibrations, I traced it to the swivel preloads, adjusted these and have had no trouble since.

Your new tyres with lots of tred have probably done something similar and exposed a weakness in the suspension. Be it shocks, bushes, tie rod ends etc, etc. The trouble is finding which component.

How do you adjust the swivel preloads? Mine has got 4 new air springs and new rear shocks, so this could be a factor. I'd rather sort what is wrong with the suspension than get another set of tyres - fix the problem rather than mask it!

Might be worth replacing the panhard rod bushes. usually transforms the handling of a RRC

The handling is fine (unless towing) - where are the panhard rods located? And are they front, rear or both? Can you replace the bushes independently of the rods?

Cheers!
 
Panhard rod links front axle to chassis. You press the old bushes out and new ones in. Replace them with blue polybush. Try getting the wheels balanced somewhere different. Another likely candidate is the steering damper which I have had fail and that made the car horrible on motorways.
 
Panhard rod links front axle to chassis. You press the old bushes out and new ones in. Replace them with blue polybush. Try getting the wheels balanced somewhere different. Another likely candidate is the steering damper which I have had fail and that made the car horrible on motorways.

I'm tempted to order one of those full bush kits and just replace everything, they're not that expensive to buy. Can they all be DIY removed/fitted or do they require specialist tools or a press to get them in?

I think I will replace the steering damper anyway, they're only £20 and easy to replace. The place I go for tyres has absolutely top notch machines, but I may get them to check the balancing again, just to be sure.

poly%20black.jpg
 
I had horrible vibration on mine until I had the swivel preloads done.
It made the car almost undrivable at speed.
You need a set of spring balances.

Your symptoms don't sound like mine though.
 
I see - I don't have one of those gadgets! Something else to buy, then. Can those shims really make that much difference?
 
From personal experience - yes!
Mine got to a stage where a trip down the motorway at 60+mph was all but impossible. The whole car would shake violently if you hit even the tiniest bump.
All better now :)
 
From personal experience - yes!
Mine got to a stage where a trip down the motorway at 60+mph was all but impossible. The whole car would shake violently if you hit even the tiniest bump.
All better now :)

See, mine shakes all the time at 60-70mph, not just when you hit a bump! So I'm not sure this will solve it. Hmm...
 
How do you adjust the swivel preloads? Mine has got 4 new air springs and new rear shocks, so this could be a factor. I'd rather sort what is wrong with the suspension than get another set of tyres - fix the problem rather than mask it! Quote




I don't think you would be necessarily be masking the problem. Whenever new suspension components are introduced to a 15+ year old motor there is always the chance it will throw up issues. Not knowing the history of your car many of the suspension components could be original and if they are they've kept it on the straight and narrow up until now.

My springs and schocks needed replacing because the springs had lost some of their tension and one of the shocks was leaking, apart from that the rest of the suspension was fine and the ride was acceptable. By replacing those components I exposed a weakness in the swivels that before had not been present.

If it had not been such a pig of a job to do the springs and shocks I probably would have have just replaced them with the originals:eek:, but because it was I researched the net which led me to the swivel preload.

But it if was a case of replacing the tyres to something less aggressive to restore the peace and quiet I would be tempted to that.
 
The steering hub on the RRC is fitted to a chrome ball using two pins (Swivel Pins) top and bottom which allows the hub assembly to turn.

The pins are adjusted by fitting different thickness and number of shims to either raise or lower the pins inside the bearing housing that the hub assembly rotates on....the more shims the looser the preload is and the less shims the tighter the preload.

You have to get the preload correct to stop the hub from rocking and moving around under load and for the steering to not feel to loose and slack.

If they are too tight the steering will not self-centre correctly and will become outright dangerous to drive.

You set the preload, by disconnecting the steering links to the swivel houseing and then using a spring balance (I use a small fishing scale from an Angaling supplier that read to the amount required) to pull the swivel housing to see how much force is required to move it....add and remove shims as necessary until the force to mve is correct.

I can't remember if you have to have the brake disck and caliper removed for this as when i did it it was all taken apart anyway to replace all the swivel housing seals.

It is wise to replace the swivel bearings that the swivel pins fit into whilst it is all apart, and replace the pins too as inevitably they will be worn too.

Not a hard job just a bit fiddley at times, make sure you get the right pins though as some models have the ABS sensor and some don't.
 
Thanks guys! First step is too see if its the tyres - as I said, CarlV8 has just fitted the same tyres (albeit 235/85/16 rather than 235/70/16) to his Disco and that drives perfectly, so I plan to swap wheels with him - if the problem disappears chances are it is my wheels or tyres. If it persists, it is something on the car.

If this is the case I'll have to start looking at all of the above - not sure if I have the technical know-how/confidence to tackle this myself, but then you only learn by doing so we'll see!
 
Hope this helps to clarify (Note: this is for the RRC with ABS)

rrc_swivel.jpg


To set the pre-load you add or remove shims (Numbered 13 in the image) until the force to turn the swivel housing (numbered 14) reaches the desired figure (as in the Workshop Manual)....
 
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When I did mine a year or so ago, I got new Pins, Shims, Bearings, Bushes, Seals and Washers from Paddock Spares.
 
I would try switching the tyres first then move onto steering damper. Panhard rod next then start looking for other issues. If this has just happened I would suspect either balancing upsetting the geometry or damper and bushes. Pre loads would show before you changed the tyres and you would likely have some movement in the swivel pins.
 

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