Please help to diagnose my "transmission" noise

Hi folks,

First heard yesterday .

A noise that increases in frequency depending on speed of the car.

Starts at about 15 mph - whether in D, 3,2, or 1 - also happens when I coast along in N

Does not happen as car is accelerating or driving up a slope - nor does it happen in reverse. Happens when I take my foot off the accelerator or the car has reached a steady speed.

I tried right and left hand turns at speed - bit difficult in Edmonton - could not discern much difference though.

I shone a torch underneath but did not see anything obviously wrong though of course I am not sure what to look for

The closest I can describe the noise is if something is lodged on a tyre - I have checked - nothing there - anyway the noise seems to be more in frequency than the rotating wheels.

Hopefully someone with more experience could shed some light on the matter ?

Alex

I had the same on mine - only ever happened on the overrun. Turned out to be tyres.

Differential nose bearings?

Think you`re gonna have to jack it up and start crawling about under it. Spin the wheels listen to wheel bearings, diffs, and transfer box. Shake the props about while you`re there (although it doesn`t sound as if this is your prob).
Remember the h-brake works on the rear prop so Chock Wheels!

Diff Noise ..or Front Prop

Thanks for the interest so far

rewmer - tyres are pumped up ok and no signs of bulging - I had an estate car once that had a weak spot on a section of tread on front tyre - though that manifested itself with steering wheel wobble - no wobble in this case. What should I be looking for.

claw/gtland - by props I take it you mean the drive shaft to the diff from gearbox - the ones with a universal joint at each end ?

Thanks so far

Alex

Mine too Where fine physicaly the only thing that was odd was that i had two directional tyres on the rear i tried swapping front to rear, but still the same. can't tell you what the problem was , but when I fitted a new set, problem gone

Looks like a leak from front diff is the culprit - will have to sort out asap.

When one front wheel is lifted clear of the ground how easily should it turn by hand ( assuming autobox in " N " and handbrake on ) ?

Thanks

stiffly

trukka said:

Looks like a leak from front diff is the culprit - will have to sort out asap.

When one front wheel is lifted clear of the ground how easily should it turn by hand ( assuming autobox in " N " and handbrake on ) ?

Thanks

Click to expand...

Said diff nose bearings, they are the first thing to lose lubricant when oil is low. Your symptoms sound a ringer for nose bearing wear.

Thanks wammers

What gaskets/seals would I be looking for to fix the leak from the front diff - I mean the "technical descriptions " ?

How many differential "nose " bearings are there and is that their description as well ? They might need changing.

My local independent should be able to tackle the job.


Thanks

Hi I had this with mine and the front diff was completley shot, the pin that carries the planet gears had worn the carrier oval and was totally scrap, both circlips had vanished and god knows how the pin didnt fly out and lock the front diff solid, before you think of rebuilding your diff I would check the pin for wear? there is a modified 4 pin diff fitted in the 4.6 but only fits the rear I believe?

2 pin front and rear diffs are the same but the front just runs backwards.

Hi jellyspanner,
pins , planet gears ? I have no idea about the innards of a diff !!

Mine is a 1998 4.6 HSE

When I lifted one front wheel at a time I could just about rotate the wheel but there were a few degrees "loose "rotational movement back and forth on each wheel before exerting pressure to turn it further.

trukka said:

Hi jellyspanner,
pins , planet gears ? I have no idea about the innards of a diff !!

Mine is a 1998 4.6 HSE

When I lifted one front wheel at a time I could just about rotate the wheel but there were a few degrees "loose "rotational movement back and forth on each wheel before exerting pressure to turn it further.

Click to expand...

Inside the diff there are 4 small gears which allow each wheel to turn at different speeds while cornering and turning etc, two of the gears are splined onto each driveshaft and the other two are located with a pin which goes through the diff carrier, ask your mechanic to check this pin and most of all the carrier for wear, sorry I havent got any photos.

My car made the same noise as yours on over run and when it got to cruising speed, from what you say the play in the wheels sounds the same, really you need to rotate both wheels as a pair and see if there is alot of movement and a clunk from inside of the front axle.

First check would be drain front axle and observe for metal fragments on the drain plug magnet....It could be a cv joint but doesent sound like it...

If you have to obtain another differential, they will want to know how many drive splines the drive shafts have...

JellySpanners said:

Inside the diff there are 4 small gears which allow each wheel to turn at different speeds while cornering and turning etc, two of the gears are splined onto each driveshaft and the other two are located with a pin which goes through the diff carrier, ask your mechanic to check this pin and most of all the carrier for wear, sorry I havent got any photos.

My car made the same noise as yours on over run and when it got to cruising speed, from what you say the play in the wheels sounds the same, really you need to rotate both wheels as a pair and see if there is alot of movement and a clunk from inside of the front axle.

First check would be drain front axle and observe for metal fragments on the drain plug magnet....It could be a cv joint but doesent sound like it...

If you have to obtain another differential, they will want to know how many drive splines the drive shafts have...

Click to expand...

Worn planet gears will cause clunks when drive is taken up but will not cause whine as they turn with the crown wheel most of the time. The only time they actually move much on their pins is if you are turning a corner and that is very little. They do not cause diff whine.