Axle tramp

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ndevans
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Axle tramp

Postby ndevans » Thu Aug 29, 2019 7:59 am

Hello world.

I have recently rebuilt my engine and gearbox (see separate threads). It's a 1275, which has been bored +040", and the gearbox has had both main bearings renewed, and the needle bearings, as well as a new layshaft & 1st gear.
There are a couple of issues with engine and gearbox, which I won't go into here.
There's a knocking or clunking noise when changing gear, which seems to come from the rear of the car. It feels like it's drive train or axle/diff related. Is this axle tramp?
I saw a video on here recently, showing the diff and axle rotating up towards the floor of the car-could this be what is happening?
Cheers N
cheers N
'69 Traveller, 1275, discs.

pgp001
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Re: Axle tramp

Postby pgp001 » Thu Aug 29, 2019 8:20 am

Have you checked the universal joints in the prop shaft ?

Phil

myoldjalopy
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Re: Axle tramp

Postby myoldjalopy » Thu Aug 29, 2019 10:26 am

I think if it were axle tramp you would actually feel the back end hopping/bouncing around - not just hear a noise. Most likely to occur if you are taking a bend too fast. I have only experienced it once - in an 803cc car! :o

ndevans
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Re: Axle tramp

Postby ndevans » Thu Aug 29, 2019 10:33 am

pgp001 wrote:
Thu Aug 29, 2019 8:20 am
Have you checked the universal joints in the prop shaft ?

Phil
Must admit I haven't yet, the propshaft was off recently when I had the engine out. Would loose bolts cause it to knock? Or would it just rattle all the time?
cheers N
'69 Traveller, 1275, discs.

Murrayminor
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Re: Axle tramp

Postby Murrayminor » Thu Aug 29, 2019 10:56 am

Worn Universal Joints will "clang" on taking up drive (letting the clutch out).
Mine did it turned out to be the UJ's on the propshaft.

Axle tramp can best be described in the chase sequence in the movie Bullitt, Mr McQueen overshot a junction and put his 1967/8 Mustang into reverse and dropped the clutch, the tyres then bounced causing the axle to jump up and down as the tyres gripped then spun then gripped and spun and so on.

See here for a https://www.youtube.com/watch?v=no7XR7s8Z7o

The Axle tramp is at 59 seconds.
Proud owner of my first Morris Minor

pgp001
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Re: Axle tramp

Postby pgp001 » Thu Aug 29, 2019 1:05 pm

ndevans wrote:
Thu Aug 29, 2019 10:33 am
pgp001 wrote:
Thu Aug 29, 2019 8:20 am
Have you checked the universal joints in the prop shaft ?

Phil
Must admit I haven't yet, the propshaft was off recently when I had the engine out. Would loose bolts cause it to knock? Or would it just rattle all the time?
I was not actually thinking about the bolts being loose, rather the condition of the bearings themselves.
Just get under the car and give the propshaft a twist, (you may need to jack the rear wheels up and try this when the car is in gear for the front end of the shaft) if the bearings are shot you will be able to feel some movement between the halves of the joint, it also shows up on the overun as a knocking noise when the direction of load on the shaft is reversed.
I had a similar problem once on my Austin 7, it turned out to be worn splines on the input end of the propshaft.

Just go through the drive train methodically from front to back and see if you can feel any play anywhere, just hope its not in the differential.

Just a thought.......Are all your suspension bushes in good nick and the U bolts done up tight on the axle ?
Phil

philthehill
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Re: Axle tramp

Postby philthehill » Thu Aug 29, 2019 10:21 pm

Are your rear axle spring seats ok?


ndevans
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Re: Axle tramp

Postby ndevans » Thu Aug 29, 2019 10:46 pm

Had the rear wheels up on the ramps tonight. Cardan shaft bolts are tight, no discernible play across the u/j at either end. There is backlash in the diff-I can turn the flange about 3mm relative to the diff casing. I think this is normal.
There is no noticeable fore & aft movement of the cardan shaft. Nothing in the rear suspension, springs, u-bolts, shackle pins or shackle plates appears loose, and as far as I can tell, there is no sign of the axle moving relative to the u-bolts or springs. Apart from appearing to sit lower at the rear on the n/s than the o/s by about 10mm (leaf springs were new a year ago), all appears normal.
Haven't looked at the front suspension closely, but a brief inspection revealed no obviously loose nuts, bushes etc (all poly) look ok.
So-where is my "clunking" coming from? I know tie rods are a possiblity-they look ok, but I will check properly over the weekend.
Could something in my newly rebuilt gearbox be the culprit? Loose bearing? Surely not, I'd expect oil to be everywhere.
cheers N
'69 Traveller, 1275, discs.

Murrayminor
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Re: Axle tramp

Postby Murrayminor » Fri Aug 30, 2019 6:37 am

Have you checked the halfshafts are secure?
Proud owner of my first Morris Minor

ndevans
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Re: Axle tramp

Postby ndevans » Fri Aug 30, 2019 7:05 am

No, I haven't checked the halfshafts, but they haven't been touched in all the recent work.
cheers N
'69 Traveller, 1275, discs.

pgp001
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Re: Axle tramp

Postby pgp001 » Fri Aug 30, 2019 8:07 am

You could try putting the car in gear on a flat surface and push/pull it against the drive train to see if you can replicate the noise.

Phil

Murrayminor
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Re: Axle tramp

Postby Murrayminor » Fri Aug 30, 2019 8:30 am

Try placing a mobile phone camera under the car with the light on, then with the engine running release the clutch and see if anything is amiss.
Try this for each of the major components such as axle,leaf springs, diff, and both ends of the propshaft.
You mention in your original post there are issues with the gearbox, would those issues cause the problem?
Proud owner of my first Morris Minor

ndevans
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Re: Axle tramp

Postby ndevans » Fri Aug 30, 2019 9:25 am

pgp001 wrote:
Fri Aug 30, 2019 8:07 am
You could try putting the car in gear on a flat surface and push/pull it against the drive train to see if you can replicate the noise.

Phil
Good idea. Job for the weekend!
cheers N
'69 Traveller, 1275, discs.

ndevans
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Re: Axle tramp

Postby ndevans » Fri Aug 30, 2019 9:29 am

Murrayminor wrote:
Fri Aug 30, 2019 8:30 am
Try placing a mobile phone camera under the car with the light on, then with the engine running release the clutch and see if anything is amiss.
Try this for each of the major components such as axle,leaf springs, diff, and both ends of the propshaft.
You mention in your original post there are issues with the gearbox, would those issues cause the problem?
Another good idea......
As for the gearbox issues (whining in 1/2/3, rattling that dies away if I hold the gear lever), well bearing in mind the gearbox has been stripped down to every last component, yes, possibly it could be related. The only way I'll know is by getting the engine and gearbox out again, which is a faff that I want to avoid, unless I have some evidence that is necessary. I want to eliminate the obvious, simple things as far as possible first.
cheers N
'69 Traveller, 1275, discs.

Edward1949
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Re: Axle tramp

Postby Edward1949 » Fri Aug 30, 2019 9:47 am

ndevans wrote:
Thu Aug 29, 2019 7:59 am
..............................There's a knocking or clunking noise when changing gear, which seems to come from the rear of the car. It feels like it's drive train or axle/diff related. ...
Can you be more specific? Does the knock happen when you re-engage the clutch after a gear-change? Can you avoid the knock if you re-engage gently? Can you replicate the knock by driving in top gear and powering on and off with the accelerator?

paul 300358
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Re: Axle tramp

Postby paul 300358 » Fri Aug 30, 2019 9:49 am

Probably a daft suggestion, is there anything in the boot rolling around? I keep a 600mm 1/2 inch drive bar in the boot, if it's not secured it clunks around.

ndevans
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Re: Axle tramp

Postby ndevans » Fri Aug 30, 2019 10:16 am

Edward1949 wrote:
Fri Aug 30, 2019 9:47 am
ndevans wrote:
Thu Aug 29, 2019 7:59 am
..............................There's a knocking or clunking noise when changing gear, which seems to come from the rear of the car. It feels like it's drive train or axle/diff related. ...
Can you be more specific? Does the knock happen when you re-engage the clutch after a gear-change? Can you avoid the knock if you re-engage gently? Can you replicate the knock by driving in top gear and powering on and off with the accelerator?


I'll have to have a drive and confirm, but from memory, it's when I disengage from say 2nd or 3rd and change gear. Can't remember if it's when accelerating or decelerating, I'll have to do some tests. It's not every time though.
cheers N
'69 Traveller, 1275, discs.

ndevans
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Re: Axle tramp

Postby ndevans » Fri Aug 30, 2019 10:17 am

paul 300358 wrote:
Fri Aug 30, 2019 9:49 am
Probably a daft suggestion, is there anything in the boot rolling around? I keep a 600mm 1/2 inch drive bar in the boot, if it's not secured it clunks around.
Daft suggestions sometimes turn out to be correct!
I don't think there's much in the boot area, but I'll have a clear out to be sure.
cheers N
'69 Traveller, 1275, discs.

ndevans
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Re: Axle tramp

Postby ndevans » Wed Sep 04, 2019 8:01 am

So after a short trip last night, it appears that the "clunking" happens when in gear, but coasting. More noticeable in 3rd or 4th.
cheers N
'69 Traveller, 1275, discs.

ampwhu
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Re: Axle tramp

Postby ampwhu » Wed Sep 04, 2019 4:50 pm

engine and gearbox mounts, take a look at them
rear hubs, any end float movement

all I can think of at the moment


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