Noisey rear end
Discussion
Some may remember, a while back, I complained about a rumbling noise that has developed since changing my rear UJs.
I have checked the bearings and they have a tiny bit of play (but apparently that is common on Jag setup??!!)
More noticably I have put the drive shaft back on in a different way to the other side(if that makes sense) The Yokes are 90 degrees different. Would this cause an in-balance, leading to the rumble?
Failing that it can only be something in the Dif itself. Is there any way of testing it??
Many Thanks,
Mike
I have checked the bearings and they have a tiny bit of play (but apparently that is common on Jag setup??!!)
More noticably I have put the drive shaft back on in a different way to the other side(if that makes sense) The Yokes are 90 degrees different. Would this cause an in-balance, leading to the rumble?
Failing that it can only be something in the Dif itself. Is there any way of testing it??
Many Thanks,
Mike
Putting the drive shaft on out of line with the other side shouldn't make any difference as the diff will gradually turn them in relation to each other anyway.
The diff/axles on these are noted as being noisey anyway, even freshly rebuilt ones. Apparently the only reason they are quiet in Jags is baceause the weight and construction of the car damps the noise out.
Not sure you should really have any noticeable play in the wheel bearing IIRC. Can you isolate which side is noisey? Perhaps by getting a passenger to turn and listen in each corner as you drive. Maybe your local MOT station may be able to help by running it on their rollers for you.
The diff/axles on these are noted as being noisey anyway, even freshly rebuilt ones. Apparently the only reason they are quiet in Jags is baceause the weight and construction of the car damps the noise out.
Not sure you should really have any noticeable play in the wheel bearing IIRC. Can you isolate which side is noisey? Perhaps by getting a passenger to turn and listen in each corner as you drive. Maybe your local MOT station may be able to help by running it on their rollers for you.
The play really is small, but it is a very bearingesque noise (ie it only happens at about 40-50mph). I think putting it on the rollers could be the best thing. Thanks for the advice. i mainly wanted to check that driving it isn't going to do any major damage and I can't see that anything is loose ( Re: brake calliper!!!!
)
mike
) mike
When you replace a UJ there are two ways of putting the bits back together. It may be that you inadvertantly got the two bits 180 degrees out, so the dynamic balance weights are no longer useful, if you have any. I asked a prop shaft balancing place a while back how much they charged to balance these shafts and they said they were too short to be balanced, and it wasn't worth it. Ho hum. Maybe they aren't balance weights after all, and just TVR putting two very big identification plates on... You could try swapping the bits 180 degrees over, or, if you are feeling lazy put a big jubilee clip on with the fat bit the other side of the balance weight near the replaced UJ.
When I did my driveshafts I asked Proptech if they should be balanced like a prop would be. They said no.
Remember they run at lower revs than the prop due to the differential ratio and are shorter which will push their resonant frequency up higher (think guitar string note vs length), so probably will never get up to speeds where resonant vibrations become a problem.
What speed does a badly balanced prop vibrate at? Multiply by the differential ratio and I'm sure you get a number outside the "envelope of performance" even for a BBW
I also imagine the stonking great brake disks (mass and diameter) mask any imbalance from the driveshaft, not to mention the wheels as well.
If you're changing UJs align the inboard grease nipples with the outboard ones. This will half the time it takes to grease them in the future as you won't have to keep rotating the wheels to get at the next grease point.
Leo
Remember they run at lower revs than the prop due to the differential ratio and are shorter which will push their resonant frequency up higher (think guitar string note vs length), so probably will never get up to speeds where resonant vibrations become a problem.
What speed does a badly balanced prop vibrate at? Multiply by the differential ratio and I'm sure you get a number outside the "envelope of performance" even for a BBW
I also imagine the stonking great brake disks (mass and diameter) mask any imbalance from the driveshaft, not to mention the wheels as well.
If you're changing UJs align the inboard grease nipples with the outboard ones. This will half the time it takes to grease them in the future as you won't have to keep rotating the wheels to get at the next grease point.
Leo
[puts on devil's advocate hat]
I had an outboard UJ go so bad there was nearly 1cm of play in the bearing - and it didn't vibrate until about about 120 on the autobahn. I discovered it because the drive shaft hit the damper on roundabouts with a clonking noise!
However, the inboard UJ may cause a problem. On the cardan shaft of my Alfas a front inbalance would resonate at 2000 to 2500 rpm, wheras the rear would be close to 5000 rpm, so it may be that an inbalance on the inside of the prop shaft near the differential could be within the normal driving range. - ie about 60mph.
[takes off devil's advocate hat]
Wheel bearings rumble, and driveshafts vibrate in my limited experience. Did you remove the drive shaft from the bearing when you did the UJ? You might have got some crud in it. Also, the lip seals on the bearing carrier apparently only seal over about 10 micrometers, so if you nick it at all, water will get in, and corrode the bearing surfaces, and you will get a rumble - the noise will start at a very slow speed and get louder and louder as you go faster whereas driveshafts tend to vibrate at only a few selected speeds.
I inspected a grumbly bearing from my old 280i, and it looked perfect to the naked eye, so I repacked it but. It still rumbled, so I replaced it with new - no rumble. Oh, and mine didn't rumble if you turned the wheel with the car on jack stands, only when they were loaded with weight of the car.
-Jim
I had an outboard UJ go so bad there was nearly 1cm of play in the bearing - and it didn't vibrate until about about 120 on the autobahn. I discovered it because the drive shaft hit the damper on roundabouts with a clonking noise!
However, the inboard UJ may cause a problem. On the cardan shaft of my Alfas a front inbalance would resonate at 2000 to 2500 rpm, wheras the rear would be close to 5000 rpm, so it may be that an inbalance on the inside of the prop shaft near the differential could be within the normal driving range. - ie about 60mph.
[takes off devil's advocate hat]
Wheel bearings rumble, and driveshafts vibrate in my limited experience. Did you remove the drive shaft from the bearing when you did the UJ? You might have got some crud in it. Also, the lip seals on the bearing carrier apparently only seal over about 10 micrometers, so if you nick it at all, water will get in, and corrode the bearing surfaces, and you will get a rumble - the noise will start at a very slow speed and get louder and louder as you go faster whereas driveshafts tend to vibrate at only a few selected speeds.
I inspected a grumbly bearing from my old 280i, and it looked perfect to the naked eye, so I repacked it but. It still rumbled, so I replaced it with new - no rumble. Oh, and mine didn't rumble if you turned the wheel with the car on jack stands, only when they were loaded with weight of the car.
-Jim
wedgtable! You have a picture on your website of my FHC getting its windscreen replaced at BBWF- cool. Shame you and silverback didn't have the space to paint my car!
To replace the wheel bearing you'll need access to a press. Freeing up the suspension bolts will be such fun - if you are really lucky you might get to replace some bushings if the bolts are too far gone. The bearing is off the rear of a MK2 Granada , but you need one extra seal. The bearing kit is £50 from a TVR specialist, or £5 off eBay (Thats what I sold my spare one for - eek). I may have a spare one in my parts bin if you are desperate.
-Jim
To replace the wheel bearing you'll need access to a press. Freeing up the suspension bolts will be such fun - if you are really lucky you might get to replace some bushings if the bolts are too far gone. The bearing is off the rear of a MK2 Granada , but you need one extra seal. The bearing kit is £50 from a TVR specialist, or £5 off eBay (Thats what I sold my spare one for - eek). I may have a spare one in my parts bin if you are desperate.
-Jim
Actually most of it was rebuilt recently (2 years ago) so fingers crossed it shouldn't be too bad.
I am afraid it is not the space down here it is the atmosphere, to dirty and a french polisher which leaves silicone in the air (which always ruins paint jobs so I have given up) I'd do mine otherwise.
cheers again for the advise.
Mike
I am afraid it is not the space down here it is the atmosphere, to dirty and a french polisher which leaves silicone in the air (which always ruins paint jobs so I have given up) I'd do mine otherwise.
cheers again for the advise.
Mike
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