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Oh no ... it'd my diff!


Jeffds1360
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Thought my uj's were away but no.... it is worse!

It is the wear in the diff. causing my 'noises' Used my tame back street garages four poster and he found it straight away. He is an ex mechanic for Carlos Sainz when with Ford and says escort diffs had 'pins' to adjust the slack. Does the herald?

It is obvious that the prop-shaft can be rotated 'quite a few degrees' before drive shafts take up the slack.

Anyone need two rimmers greasable ujs?

Whats next step guys? Is it 'shimmable'?  do I need new innards ? Is an exchange diff available.

What route have you guys taken?

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The conventional wisdom, started by the great John Kipping and found to be true by many others, is that differentials don't knock or vibrate. The diff on my Spitfire has quite a few degrees of rotation before making the half-shafts move too and it is still very quiet in operation.

You can't really tell how worn the UJs are until you have unbolted them and removed the spring loading. I really would urge you to change the joints before spending huge amounts on a reconditioned diff, especially as you have the new UJs already. You'll find all the encouragement and moral support you could wish for on here.

Adrian

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Apart from your doomsayer mechanic, what is the problem? What noises do you have? As Adrian said, diffs don't knock, clonk, tap or any other such noise. They can cause vibration but only when really shot - like, great big hole in the casing shot - notwhen just a little worn. A bit of play in the propshaft - and "quite a few degrees" is hardly anything really - is normal and harmless.

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Oh.... fiddlesticks... thanks guys. What a conundrum!.

The noise is a thrum thrum thrum at wheel rotation speed. It happens under load and deceleration, also when going left, right or straight.???? But...not all the time..... right, ujs first. Decision made :)

thanks all.

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OK, it is possible to get a thrumming from a diff... but it's actually more common (especially if it's at wheel speed) for it to be wheel bearings. Look under the car at the brake back-plates. If either of them is askew - not perfectly aligned with the drum - then it suggests quite severe bearing issues. Also look for signs of the grease having escaped, either along the shaft or into the drum and out of the hole just below the bearing carrier. Of course, if the shafts are coming off to do the UJs then you can inspect for any bearing play while you're at it. Or rather, before you start on the UJ, as the inner bearing tends to take the shaft out with it and you don't want to be replacing a UJ only to find you need to replace the shaft you just fitted it to!

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25 minutes ago, NonMember said:

OK, it is possible to get a thrumming from a diff... but it's actually more common (especially if it's at wheel speed) for it to be wheel bearings. 

As famously quoted to me by a mechanic at BLRC (Landrover Centre in Co. Down) when looking at a Freelander 2 - "It's your differential! I'd stake my career on it. £1200 minimum."

£95 fitted a new bearing at another garage and it went for years after that.

Jeff - when you say it doesn't happen all the time - can you identify when it doesn't happen?

 

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the free play in the prop is nothing to do with crownwheel backlash its caused by the thrust washers on the planet and sun gears and doesnt matter at all .

the diff mounting distance of the pinion and backlash of the craownwheel is controlled by shiming the bearings  not a job for the fainthearted or without a carrier spreader 

i suggest you find another carlos the one youve got is out with the fairies 

stick to UJ or wheel bearing   always do the simple first ,and if possible the cheapest , never dig deep pockets based on the daft opinion of an exspurt

Pete

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Thanks for that but I have checked wheel bearings and they are sound, my back plates are square with no grease visible. 

I'll have a bit cruise out tomorrow and try to get a better feel of what where and how the thrumming occurs.

Thanks again all. I'm going to join up properly after 5th when pension arrives. ATB. 

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yes a slow drive take some corners , which side does it emanate from,  

get someone else to listen with you, and the rotation frequency of the rumble  any thing wheel speed start with the wheel and finishes at the diff output shafts 

not the diff itself. 

does applying brakes change the noise and so on 

but any noise more on corners at low speed is going to be your UJ   as everyone has said 

Pete

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Another test is to drive along at a speed when the thrum thrum occurs then change gear. If the noise is the same then it's definitely from the gearbox back. 

In the seventies I had a Mk2 Escort that had a nasty drum at around 60-70mph. After the local Ford dealership emptied my pockets an old guy said it's your new rear tyres and to prove it he put another set of wheels on and he was right! I had travelled all the way back from Inverness at 50-60mph thinking my diff was about to explode when it was the crappy new tyres to blame! Have you recently changed your tyres?

I also had an Alfa with a dodgy diff which used to clonk when I backed off that was just wear but didn't drum.

Iain

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bearings in these diffs seem pretty bullet proof if run with a lack of oil the pinion bearings being splash lubed are the first  brg  high loaded to fail and if in a poor way will 

whine not rumble and are running at engine speed where the wheels will be doing 4 time slower so the noise frequency is quite different 

rumbles are more road wheel speed failures  , so back to UJ or hub bearings  both will change the song  with  cornering forces 

 

 

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15 hours ago, Badwolf said:

I put up with something very similar for years. Did the ujs last year.. noise gone. In a way I miss it. It was part of the car for ssooo long. Now still picking up needle bearing from around the garage from the old ujs.

As long as you're sure they're from the old UJS... :) Iain's post on tyres is quite interesting - was the car standing for any length of time ie could there be a flat spot in one or more of the tyres?

 

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Iain and Colin's posts on tyres are well worth considering.

I had a VW Golf years ago where the rear tyres went out of shape and produced a rythmic thrumming around 50mph. The car was about 5 years old with 50k miles on the clock and being FWD, was still running on the original rear tyres. The tyre fitter said tyres going out of shape was a common problem.  A new pair of tyres solved the problem. 

Nigel

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56 minutes ago, Colin Lindsay said:

As long as you're sure they're from the old UJS... :) Iain's post on tyres is quite interesting - was the car standing for any length of time ie could there be a flat spot in one or more of the tyres?

 

There were plenty of bearing in the new ones. I don't think that a few missing would make much difference!!!!

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16 hours ago, Badwolf said:

I put up with something very similar for years. Did the ujs last year.. noise gone. In a way I miss it. It was part of the car for ssooo long. Now still picking up needle bearing from around the garage from the old ujs.

Hi.  On Vitesse, I've had a fairly quiet, thrumming/drumming sound for about the last 6000 miles, that doesn't appear to have got worse, (sounds like from rear nearside) at a constant speed in the range of 55-65 mph (not sure at speeds above this). Disappears if accelerate/de-accelarate.

Was hoping it might go when I had new tyres recently. No.

Should I just leave it?.  Only concern is if hub bearing or shaft U/J mullers drive shaft.

Thanks, Dave 

Edited by daverclasper
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Eeeeeh well, after a 30 mile trip I am much more at ease. My wife could not even hear the thrumming!!! I too actually found it difficult to find a situation where it was noticeable... 5mph, right hand bend under gentle throttle....maybe.??? No change when braking or in various gears. Definitely wheel rotation speed related

My previous test trips were all in my estate with semi-detached houses  and walled gardens 5' away. I guess the sound was echoing back and seemingly amplifying it to such an extent it became foremost in my thoughts.   Something to keep an ear on in the future :)

Thanks for all the help and advise Lads, you are all stars........... My tyres are round btw :) 

Next step is the 1-2 mm play in steering wheel to column up down left and right. ... is that enough to require a top bush? (or MoT fail.

no play in rack or joints btw,  The road wheels move at the slightest rotation of the steering wheel.

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Cheers Pete, I've had a couple of wheels off and all is standard. Trims are very clean and tidy as are hub caps. Nuts are done up to my standard 'tug' - that's not too tight! Some garage windy guns are set to a massive torque!  Just had a run through my estate and it is audible again! Thrum thrum thrum at 10 mph straight road light throttle. Mind.....I have fixed the interior light and door switches work now so I'm happy for the day :)

Wife is not happy though.... the chassis is coated in some black oily greasy/gritty crud and some small blobs dropped on drive and I tramped some in house!... it's war!

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