Cabrio rear bearing noise?

[mike woodley]

Hi,
I have just replaced the offside rear wheel bearings on my Sierra based Cabrio as i thought they had worn and were causing a noise. I was getting a noise from around 40mph. It was not a whine but more a wha, wha, wha, wha sound which increased in speed, with the speed of the car. Sadly have just got in from a test run and the noise is still there. Unless i have done the wrong side, i am at a loss as to what it could be. Has anyone else experienced this sort of noise from the rear of their Cabrio?
Any ideas or advice as to what could be causing the noise would be greatly appreciated.
Regards Mike.

[scott h]

Re: Cabrio rear bearing noise?

I had a similar problem with my Mondeo which turned out to be the tyres. Although the tyres were less than two years old with plenty of tread they were misshapen. Swap front and rear wheels and see if the noise moves to the front.

[Alan c]

Re: Cabrio rear bearing noise?

Consider prop shaft - check UJs

[chris_cussen]

Re: Cabrio rear bearing noise?

I used to get wha wha wha noise when being chased by Mr.Plod

[wiggiesworld]

Re: Cabrio rear bearing noise?

I had a similar problem with my Mondeo which turned out to be the tyres. Although the tyres were less than two years old with plenty of tread they were misshapen. Swap front and rear wheels and see if the noise moves to the front.

Agreed, always a good first step is to check whether your tyres have gone out of shape. This happens more than you would think.

[mike woodley]

Re: Cabrio rear bearing noise?

Hi Everyone,
Thanks for all the advice. Have tried swapping tyres around, checking UJ's drive shafts and all to no avail, the noise was still there. Put the car up on blocks and ran it in gear and found horrible noises from the diff useing a VERY long screwdriver to listen, hubs OK. So now to find a 3.62 final drive push in shaft type diff. My Cabrio has the thicker 27mm drive shafts, will any 7in push in type diff be suitable?
Thanks once again for the advice.
Mike

[greyV8pete]

Re: Cabrio rear bearing noise?

Hi Everyone,
Thanks for all the advice. Have tried swapping tyres around, checking UJ's drive shafts and all to no avail, the noise was still there. Put the car up on blocks and ran it in gear and found horrible noises from the diff useing a VERY long screwdriver to listen, hubs OK. So now to find a 3.62 final drive push in shaft type diff. My Cabrio has the thicker 27mm drive shafts, will any 7in push in type diff be suitable?
Thanks once again for the advice.
Mike

Hi Mike. It sounds like a diff carrier bearing has failed. First I would get the diff out and take the rear cover off and have a look what is going on inside. Although setting up a diff from scratch is not for the faint hearted, in your case it should be possible to replace just the diff carrier bearings, as you only then need to check and reset the backlash between the crown wheel and pinion.


Give me a call when you have it stripped down and I can pop up and have a look at it for you, or you can bring the bits to me.


If you do have to get a replacement then with a V8 consider a lower ratio if you can find one! I fitted a 3.38:1 in mine and it gives much better cruising and with the V8 any loss of acceleration is hardly noticeable.


As far as I know the flange type diffs have the same configuration and diameter at their inner ends as the push in type. You need get the rear cover off to remove the inner circlip from each one so they can be pulled out. Obviously you need to check dimensions carefully.


I bought my diff from John at KitFit. His are second hand but he always checks them over for wear etc and replaces the seals before shipping them. I have always found him very helpful.


Give me a call if you want to chat about it. Peter.

[scott h]

Re: Cabrio rear bearing noise?

Just had a quick look on ebay. This is a link to one of several at the moment.

https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F264355738029

[greyV8pete]

Re: Cabrio rear bearing noise?

Just had a quick look on ebay. This is a link to one of several at the moment.
https://rover.ebay.com/rover/0/0/0?m...2F264355738029

Thats a pretty clean set of teeth and would make a quick swap. Not too far away Mike for you to collect! :-)

[mike woodley]

Re: Cabrio rear bearing noise?

Hi,
Thanks again for all the advice. Now looking to buy another push in type diff. Seems to be quite a few to choose from out there.
Are the push in type diffs the same, apart from ratios, in the full range of Sierra's, i.e.1.6, 1.8 & 2.0 ltr? That is the build, casing, bearings, crown wheel and pinion etc.
If they are, then my thinking is to go for a diff from a lower power 1.6 or 1.8 as they will have had less stress put on them and should have a lot more life in them.
Its going into my 200HP V8 Cabrio.
Am i right in my thinking or not?

[milliemarlin]

Re: Cabrio rear bearing noise?

Sierras have pretty robust diffs. I think you have been unlucky to have one fail. I would not choose based on potential wear. I have been told the 1:9 is best for a 2L Cabrio.
Paul

[scott h]

Re: Cabrio rear bearing noise?

Hi,
Thanks again for all the advice. Now looking to buy another push in type diff. Seems to be quite a few to choose from out there.
Are the push in type diffs the same, apart from ratios, in the full range of Sierra's, i.e.1.6, 1.8 & 2.0 ltr? That is the build, casing, bearings, crown wheel and pinion etc.
If they are, then my thinking is to go for a diff from a lower power 1.6 or 1.8 as they will have had less stress put on them and should have a lot more life in them.
Its going into my 200HP V8 Cabrio.
Am i right in my thinking or not?

Here is a pic of my Haynes Sierra manual. It would seem that the only difference is two sizes of crownwheel.

20190616_115049-1224x1632.jpg

I know that there are two widths of casing, 7ins and 7 1/2 ins, when measured across the top long bolt bracket, but I think this is one difference between push in and bolt on shaft differentials.

My thoughts on engine size v's diff wear are that total mileage will have a much bigger effect. Once a Sierra is up to speed, which is by far the highest proportion of total journey time, it will use the same power to maintain that speed regardless of engine size.

[philcoyle]

Re: Cabrio rear bearing noise?

Mike,
having shredded 2 Marina axles I would not recommend an axle from a lower powered vehicle. I have fitted a Ford Capri Laser Axle limited slip diff and after 12years it has not caused any problems (Hope I haven't just jinxed it) go the same hp or a bit higher but I would steer clear of lower.
Only problem I created was having to widen the car by about 8 inches, and fit a Ford escort mk11 steering rack forward of the front axle.

Phil

[mike woodley]

Re: Cabrio rear bearing noise?

Thanks for that. Helps my decision making no end.

[chris_cussen]

Re: Cabrio rear bearing noise?

I'm willing to be shot down in flames but: ignoring XR4is as far as I know the internals of the Serria diff are good for at least 250bhp regardless of the donor vehicle and diff ratio..
The differences depend on the type of joints (Lobro or tri-pod) for the half shafts. Lobro were fitted to cars with disc rear brakes.
You may find this useful https://www.locostbuilders.co.uk/for....php?tid=85080