Excessive road noise

certainly very impressed with Uniroyal Tyres, got them on all of the cars in slightly different flavours. Nice for classics as they've got slightly softer sidewalls than normal, seems to suit the older suspension systems.

DSC_0560 by 1275midget, on Flickr
 
Well having recently had to press into service the original 40 year old Avon spare for the short journey back home, tyres at the rear make a colossal difference too. Road noise very much diminished.

Looks like there is a reason why all that soundproofing is under the rear seat. The weird thing is I could have sworn the noise before came from the front......
 
Not only that, but wheel bearings at the rear and UJs on driveshafts and propshaft that are beyond their best add to what appears to be "road noise".
When i did renew the whole set at once in my TC the difference in "road noise" was significant.
 
Time for some thread revival!

I’ve done several jobs on the car to try and improve the road noise, but it still remains. First I tried stripping and re-greasing the existing wheel bearings. There didn’t appear to be anything wrong with them, and this didn’t make any difference to the noise. Next, I’ve tried replacing the brake discs, and fitting new front bearings. The old discs were a bit pitted, so I wondered if that was causing noise that transmitted into the car. The car then spent a year in the workshop whilst I got bogged down with other jobs. Yesterday was the first time out back on the road for a decent trip, and frustratingly the noise still remains.

I’m becoming more and more convinced this is tyre noise. If I find the right texture tarmac, it improves! Maybe it’s time to fork out for a new set of Pirelli’s?
 
Having run older Land Rovers for years, which are not exactly silent, two things spring to mind that can significantly influence in cabin noise.
1)Tyres 2) Any, even small, hole in the body shell . Make sure all grommets around cables , gearshift etc and plugs are in place .
Talking to one of the design engineers who worked on the P6 when under development, He said the P6 was the first monocoque vehicle Rover had developed and the first with radial ply tyres, both things have their own significant influence on noise. On tyre noise , they worked closely with Pirelli to come up with a tyre that was acceptable .
 
Note that many (if not all) tyres now come with a noise rating - maybe mandated by EU? Had a cyclic noise once (rpm dependent) that I couldnt find, soon after fitting a new fan belt. Eventually checked the working faces of the belt and there was a chunk missing...
 
Tyre noise measurements are taken from outside as the car drives past and doesn't have too much relevance to noise in the cabin. The P6 tyre noise (road noise) is worse than many cars of the era as the suspension is mounted back up to the bulkhead, which can easily transmit the noise into the cabin. The heads of the bolts/studs that hold the front suspension onto the car are actually inside the car, behind the glove boxes.

Modern road surfaces really don't help either.

Mine is a little noisy on the N/S front as I know the stub axle has some scoring on it. I will be sorting that shortly :)
 
One question; what sort of condition is the rubber bushes and dome like on the front suspension? If those are at their end of life you will hear a lot more noise.
 
Road surface has a massive difference on road noise. I think concrete surfaces offer the ultimate test.
A short stretch on the inside lane of the northbound M11 approaching the M25 sets up an alternating hooning noise on one of our cars so it's also tyre dependant of course.
 
Concrete roads have drainage slots. Roads with the slots across the carriage way will make your ears bleed, however we have a stretch near us with the slots running with the road, it is so quiet you think you have gone deaf.
 
One question; what sort of condition is the rubber bushes and dome like on the front suspension? If those are at their end of life you will hear a lot more noise.
I’ve not had the front suspension apart and off to check completely. However, they are both still there, and from the outside look in good condition and still feel compliant.
 
Concrete roads have drainage slots. Roads with the slots across the carriage way will make your ears bleed, however we have a stretch near us with the slots running with the road, it is so quiet you think you have gone deaf.

Saying that, it must depend on the concrete mixture. The surface to the east of the Potters Bar junction on M25 (for one) is horrendously noisy with the joints setting up an entirely different accompaniment to the stony cacaphony. The A12 up near Colchester is another one with the very worn tarmac skim (assumedly laid in an attempt to quieten it down) now adding to the symphony. :eek:
 
I’ve done a few more miles now. The noise is definitely road surface dependent. On the right patch of tarmac it disappears.

So possibly tyres? Either the inherent design and construction of the ones I have, or they’re just a bit worn and a new set would help. It’s an expensive experiment though, to find out what make and model works best.

Another area I’m going to look at, which is much cheaper to diagnose and fix if necessary, is the wheel trims. They look and feel like they’re made from McDonalds ash trays, and when tapped, there’s the same distinct metallic ring. Tapping on the side of the tyre produces the same ring too, but doing it with a hand on the wheel trim at the same time doesn’t cause a problem. I’ll run without them first to see if it makes a difference, and if so, a section of sound deadening pad on the back should sort things.
 
Here is a tip to help diagnose noise leaking in through door seals not doing their job. Cut some newspaper into 1-2" wide strips. With somebody sitting inside, lay the strips from inside to outside (door partly open) every few inches all the way around, and shut the door. See if any of the strips can be pulled out past the rubber seals very easily , indicating poor contact with the door body. One of the worst areas can be the forward end of the rear wheel arch that is covered by the door - lots of tyre noise there, and if the rubber seal there is not in good contact with the door it will get noisy,
 
And of course as you probably know, only use rubber not poly in your suspension and steering.


Graeme
 
I’m not a fan of poly bushes. A triumph of marketing over engineering function in my opinion.
 
I’m not a fan of poly bushes. A triumph of marketing over engineering function in my opinion.
Yep, they definitely take a set over time too. It’s a problem with polyurethane, especially in environments where you get higher temps in the summer.
 
Another update on this. I’ve just replaced all 4 tyres as the ones on there we’re getting on a bit. So far, I think things are improved, but the noise isn’t eliminated. It’s a while since I drove the car far on the old threes as it’s been laid up over winter. I can still detect a difference between tarmac surfaces, but overall the noise is reduced. Placebo effect maybe, as can’t do back to back A to B to A testing.
 
Another update on this. I’ve just replaced all 4 tyres as the ones on there we’re getting on a bit. So far, I think things are improved, but the noise isn’t eliminated. It’s a while since I drove the car far on the old threes as it’s been laid up over winter. I can still detect a difference between tarmac surfaces, but overall the noise is reduced. Placebo effect maybe, as can’t do back to back A to B to A testing.
Are you expectations realistic? Have you ridden in a known "sorted" car over a known surface? TBH I find mine near silent below 50mph and then it's wind noise all the way. I can however listen to a podcast through a cheap phone speaker at 82mph (130kphn) through France so it's not bad for the period.
Another possibility is contact from the engine or transmission to the body. Make sure the mountings are present and correct.

TBH these cars are of an age where nothing short of a strip and rebuild of the suspension will sort certain issues. I have some unwanted movement on one side at the front of the suspension. 4 people have looked at it, the individual bushes have been pushed and prodded and there's nothing obviously wrong with it. Yet..... Annoyingly......
 
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I’ve not been in another P6, but it used to detract from the enjoyment of the car. Now it feels less intrusive, and is on par with the engine/transmission noise and wind noise. I don’t expect it to be as good as a modern car but given the Rover’s reputation for ride and comfort I expected it to be better than it was.
 
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