Another chuffing noise
Discussion
adam quantrill said:
This is a useful piece of advice if you're trying to diagnose things:
Bearing whine tends to be there from low speed all the way up and doesn't vary much as you ease on and off the pedal. Gear whine is at tooth contact frequency and is most prominent around 60-70mph (about 2000 Hertz). You can 'play' diff gear whine on the throttle and its sometimes more prominent on the overrun when the 'rear' sides of the teeth touch
We had issues with gear noise on straight cut industrial gearboxes a few years back. When we analysed the noise spectrum, we saw that the noise was in fact a combination of three pitches - one at tooth contact frequency, one at twice tooth contact frequency and the third (you guessed it!) at three times tooth contact frequency! It did allow us to work out exactly which gear pair was causing the issue, out of the four possible.Bearing whine tends to be there from low speed all the way up and doesn't vary much as you ease on and off the pedal. Gear whine is at tooth contact frequency and is most prominent around 60-70mph (about 2000 Hertz). You can 'play' diff gear whine on the throttle and its sometimes more prominent on the overrun when the 'rear' sides of the teeth touch
adam quantrill said:
Mr Tank said:
A1 Gearboxes in St Neots, they have rebuilt three LSD diffs out of wedges for me.
It didn't cost a lot....
Possible, and not that far out of my way.It didn't cost a lot....
What was the average price?
I think it was between £350 to £450 depending on what needed replacing, or they will replace the lot if you want, it just like how longs a piece of string.
Regards
Andy
Cheers Andy,
well I have it sully apart now and even have the front bearing shells out, it isn't that hard to work on, just a matter of putting it back together now with some new front bearings.
I must say that I've heard tell you can replace the front oil seal with the diff on the car, I actually found this one of the trickier things to remove, I had to make a puller to pull it out using the front bearing (that I was going to replace anyway.
I'm pretty sure now that the front bearing has been causing the problems including the "steering left noise disappearing" phenomenon. I could see some evidence of asymmetric wear. I wonder if the wedge propshaft geometry could contribute, where the jag input shaft is offset from centre whereas the gearbox output is on the centre line.
well I have it sully apart now and even have the front bearing shells out, it isn't that hard to work on, just a matter of putting it back together now with some new front bearings.
I must say that I've heard tell you can replace the front oil seal with the diff on the car, I actually found this one of the trickier things to remove, I had to make a puller to pull it out using the front bearing (that I was going to replace anyway.
I'm pretty sure now that the front bearing has been causing the problems including the "steering left noise disappearing" phenomenon. I could see some evidence of asymmetric wear. I wonder if the wedge propshaft geometry could contribute, where the jag input shaft is offset from centre whereas the gearbox output is on the centre line.
Well despite the obvious fault with the diff pinion bearing the same noise is still there with the replacement diff in place.
I suppose on the good news side I have caught the diff before terminal failure, I've flushed the rear brake fluid where a seized bleed nipple would have thwarted that job, and the handbrake mechanism actually works properly now. Plus I caught some corrosion on the back chassis just in time.
The old diff will be reconditioned when I have some more time but for now back to the noise.
- I've bought a contact microphone I can clip onto various parts to help narrow down the noise source while driving along. It plugs into one of the boys guitar practice amps. It should at least tell me which corner it's coming from!
- I spotted a UJ was a little loose so have some replacements ready to go on. Even though it's not usually this sort of noise that it causes but I'm scraping the barrel now.
- The nearside rear bearings have a grease nipple fitted and are re-greased, will do the other side next (had to order another 2.5mm drill bit)
I suppose on the good news side I have caught the diff before terminal failure, I've flushed the rear brake fluid where a seized bleed nipple would have thwarted that job, and the handbrake mechanism actually works properly now. Plus I caught some corrosion on the back chassis just in time.
The old diff will be reconditioned when I have some more time but for now back to the noise.
- I've bought a contact microphone I can clip onto various parts to help narrow down the noise source while driving along. It plugs into one of the boys guitar practice amps. It should at least tell me which corner it's coming from!
- I spotted a UJ was a little loose so have some replacements ready to go on. Even though it's not usually this sort of noise that it causes but I'm scraping the barrel now.
- The nearside rear bearings have a grease nipple fitted and are re-greased, will do the other side next (had to order another 2.5mm drill bit)
Some progress today with the noise. I have rigged up a coax cable to the underside of the car with a 1/4" jack so I can plug it into a battery powered guitar amplifier.
Under the car on the other end is the contact microphone.
First clipped it onto the offside diff carrier. It was a bit noisy but didn't seem unusual and no whirring noises. Turned down the volume control to set the gain.
Then I moved the mic over to the other side - it was like night and day! Massive whirring noises, that alter on cornering too.
The odd thing is the bearing is quite quiet when the wheels are off the ground, and it has ho play. This is what has been putting me off diagnosing the fault.
Looks like I have a new diagnostic tool....
Under the car on the other end is the contact microphone.
First clipped it onto the offside diff carrier. It was a bit noisy but didn't seem unusual and no whirring noises. Turned down the volume control to set the gain.
Then I moved the mic over to the other side - it was like night and day! Massive whirring noises, that alter on cornering too.
The odd thing is the bearing is quite quiet when the wheels are off the ground, and it has ho play. This is what has been putting me off diagnosing the fault.
Looks like I have a new diagnostic tool....
adam quantrill said:
Some progress today with the noise. I have rigged up a coax cable to the underside of the car with a 1/4" jack so I can plug it into a battery powered guitar amplifier.
Under the car on the other end is the contact microphone.
First clipped it onto the offside diff carrier. It was a bit noisy but didn't seem unusual and no whirring noises. Turned down the volume control to set the gain.
Then I moved the mic over to the other side - it was like night and day! Massive whirring noises, that alter on cornering too.
The odd thing is the bearing is quite quiet when the wheels are off the ground, and it has ho play. This is what has been putting me off diagnosing the fault.
Looks like I have a new diagnostic tool....
Blimey, sounds a very interesting way to diagnose the noise, but if it works then well done. I had no noise whatsoever on a rear wheel bearing on the 390SE, until it completely let go and failed........ giving me almost 3" of movement.Under the car on the other end is the contact microphone.
First clipped it onto the offside diff carrier. It was a bit noisy but didn't seem unusual and no whirring noises. Turned down the volume control to set the gain.
Then I moved the mic over to the other side - it was like night and day! Massive whirring noises, that alter on cornering too.
The odd thing is the bearing is quite quiet when the wheels are off the ground, and it has ho play. This is what has been putting me off diagnosing the fault.
Looks like I have a new diagnostic tool....
Some good news at last - took out the split pin and had another go at moving the nut, this time with wheel on and handbrake on, in gear and chocked.
After bending a 1/2" drive bar I joined the breaker bar to it on both sides of the bar adapter, and after bening my breaker bar in the middle, it finally moved.
Also in another stroke of luck I found out one of my son's rugby team dads owns a garage with a couple of presses and negotiated having the bearing pressed out and back in.
After bending a 1/2" drive bar I joined the breaker bar to it on both sides of the bar adapter, and after bening my breaker bar in the middle, it finally moved.
Also in another stroke of luck I found out one of my son's rugby team dads owns a garage with a couple of presses and negotiated having the bearing pressed out and back in.
Well my hub had been pressed, new bearing in, off to collect it this morning.
Also new HT bolts are here so I have the full set for replacing any others that go, but I will be doing just the 5" one as the 6" one was done last year anyway.
Hopefully it will all go together without a hitch, plenty of grease in the bearing, and we'll be back on the road. About time too!
Also new HT bolts are here so I have the full set for replacing any others that go, but I will be doing just the 5" one as the 6" one was done last year anyway.
Hopefully it will all go together without a hitch, plenty of grease in the bearing, and we'll be back on the road. About time too!
Drove to work today, first "whoo hoo hoo" moment for months when I hillclimbed up Madingley hill in first then second. We have so few hills around here!
Bearing is now quiet, whirring noise gone.
THe old one must have had water ingress through the seal as thre was some mucky rusty looking grease in the inboard side.
The old style seals are solid rubber and once they wear they lose sealing ability, the new style ones have a metal spring inside the lip to keep them closed on the shaft for longer.
Nothing in the old bearing was actually broken, which is why I didn't diagnose it for so long, it wan't flopping about or getting loose.
Only problem is, now the whirring noise is gone, I can hear all the other squeaks and grinds when I put the power down!
Bearing is now quiet, whirring noise gone.
THe old one must have had water ingress through the seal as thre was some mucky rusty looking grease in the inboard side.
The old style seals are solid rubber and once they wear they lose sealing ability, the new style ones have a metal spring inside the lip to keep them closed on the shaft for longer.
Nothing in the old bearing was actually broken, which is why I didn't diagnose it for so long, it wan't flopping about or getting loose.
Only problem is, now the whirring noise is gone, I can hear all the other squeaks and grinds when I put the power down!
Edited by adam quantrill on Monday 24th September 20:49
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