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Scalloped tyres, particularly if they are muddies will cause vibrations, no matter if balanced. 'Square' tyres, such as occurs with bias ply tyres that have stood for a while will also shake - although you probably have radial tyres, some may have suffered some carcase problem.Quote:
Originally Posted by DEFENDERZOOK
I would try some other tyres, beg or borrow if you don't have enough spare.
Sorry - double post
Scalloped tyres will make a lot of noise and sound and feel like a wheel bearing is shot........
But I have a wheel balance problem.....and a wobble which is coming in at different speeds......so there's really no consistency.......
That's what's making me think it may be bushes.....as they may change position and do different things......
I do have the factory wheels here and I will swap them over if I get a bit of extra energy over the weekend.......and a bit of dry weather.......
Just to see what changes if anything.........
If I could see the wobble from outside the vehicle.....such as by driving along next to it when it's having a fit.......I may just be able to tell what it is straight away.......it's easy to pick dodgy shocks......or buckled rims......or a few other worn components.......
But from the drivers seat......well......can't really see too much......
Quote:
Originally Posted by DEFENDERZOOK
gaffa tape your iphone / video camera to the bull bar :wasntme:
Hey......don't laugh......you just gave me a great idea........
My mate has a go-pro.........might just have to borrow it for a little while.......plenty of places to mount it under a defender.......
Thanks.......
I recently had a problem with muddies that scalloped alternate edge blocks (these blocks were narrower in the tyre pattern). At a particular speed (80 to 85 km/h) they were shaking the vehicle badly. I assume the frequency was related to the spacing of the scallops and also contributed to the wear rate of the scallops.Quote:
Originally Posted by DEFENDERZOOK
Quote:
Originally Posted by Bush65
That seems to be a pretty common wear pattern on MT's, it's what I usually end up with if I haven't rotated frequently enough.
Speaking of using an outside observer, years ago when I was in my late teens, Dad had a Jeep that had the front end take off at a certain speed on a particular bump. I think it had either 11R-15's or 31-10.5R-15's on heavily offset rims.
I stood on the side of the road to watch as he hit the bump at I think an indicated 35mph.
Both front wheels just started oscillating wildly as the tie rod bowed and wobbled and flexed up and down alarmingly. It was a pretty amazing thing to observe !
The old full size Jeep used a front mounted tie rod and IIRC it was a larger OD than Land Rover use in the 90/110/130.
Some angle iron tack welded along it's length cured it, (we didn't have any tube the right ID) then I added a steering damper.
Problem solved.
Ok here is my 10 cents worth.
By balancing your wheels on a static balancing machine (the same type as used in tyre workshops), all you have done is added lead weights around the circumference of the rim to mask and counter act the fact you have missing or worn rubber on your tread. Just because the machine gauges say 'zero, all good', that means jack s#*t, it just means the wheel centrifugally weighs the same when free spinning in a circle. To exaggerate my point, if Bridgestone made a completely square tyre to fit on a 16" round rim, you could also put that on a static balancing machine and weight that up to read zero too. But that doesn't necessarily mean it's going to drive smooth on the road afterall it's the black rubber on the outside circumference that contacts the road surface, not the lead weights on the rim.
If you are serious about balancing your wheels, try a dynamic balance, then I'm sure you will change your mind. The dynamic balance involves putting your perfectly static balanced wheel on a steel roller and running it up to full road speed to simulate what it's doing once the tread is contacting the road surface. By this point I'm sure your balanced wheels would be trying to jump off the roller. Deformities and imperfections in the tread where it contacts the road is crucial, this is why your wheels are dancing around. Once you get to a certain road speed and a bump is hit it generates a harmonic oscillating frequency that no amount of lead weights around your rim, or new shockers, or steering and suspension bushes can fix, the laws of physics make sure of that, you would be throwing good money after bad to start replacing things that aren't causing your problem.
The only time you should ever need to balance your wheels is when your tyres are brand new, because dynamically the outer circumference of the tread is perfect (except Chinese tyres) which will give a dynamically perfect ride and you are only static balancing the wheel to 'fine tune' the centrifugal weight distribution to make it perfectly balanced in all areas. If you had a big brake lockup and shredded a flat spot on the tyre, forget trying to static balance it, you are wasting time and money, you could put 200 grams of weight on the flat spot side of the tyre to make the static balancing machine say it's perfect, but as soon as that tyre contacts the road it's gonna howl and jump and shake and wobble etc because the circumferential tyre tread is no longer dynamically perfect. Get what I mean ?
A construction road that gets a lot of truck traffic is always corregated for the same reason, the truck tyres generate a harmonic frequency on the dirt surface that pounds it into ruts, you can't fix this problem either.
I am like yourself in some ways, I have also purchased second hand tyres off ebay. It's a risk because you could be buying someone elses rubbish tyres they removed for the exact same reason as you are having right now, but they will never tell you that in their ebay listing will they? I never balance mine because as mentioned, if the tread surface is second hand, damaged or unevenly worn you are wasting your time trying to static balance, if it's bad enough to feel through the steering on a steer tyre I will either shift it to the rear where it could be quite happy and cause no suspension vibrations, use it on a trailer or just scrap it as a bad mistake. Sometimes I get lucky and other times I don't. Sometimes one mans trash is another mans treasure, but other times another mans trash is exactly that.
If you are in Melbourne I'd be more than happy to swap a spare set of Defender rims of mine to your vehicle to prove there is nothing wrong with your bearings, shockers, steering damper, swivel pin preload, suspension bushes etc etc. And I'd be confident to put $100 on the table as a wager that says I'm right.
I've got other wheels to try......just have to get out there and swap them over.....
But it's pouring with rain right now and I can't be stuffed.......
What you say makes sense.......and I'm just taking it all in and thinking......would different pressures affect at what speed the harmonic frequencies kick in and start causing the vibrations......due to the different flex in the tyre.........?
ok...a bit of an update........
i have put the factory wheels and tyres back on.......and it hasnt made any difference.......
but what i did discover today is that under acceleration.....it doesnt wobble.....
it does it if im up to speed.....and am either coasting or on overdrive......
so by playing with the throttle....i can basically control the vibrations......
so im back to thinking the bushes are at fault.....?
i was also thinking the track rod might be flexing for some reason......although it should be engineered enough not to......
when i get the dollars together.....ill change out the front radius arm bushes.....
just thought id update this thread for those that may be interested......