Sound deadening for diff whine

[jpbritten42]

Evening all

This may be an old topic but I'm trying to come of with a way of reducing the volume of the diff whine at cruising speeds of 50-60mph.

I appreciate the old 'TATHS' responses when it comes to the last Ford diffs so I wondered if anyone had tried tackling the issue by fitting sound deadening to the boot area and / or the panel that sits behind the seats.

Has anyone tried it and if so what material / product did you use for the material..?

Any advice or feedback would be greatly appreciated! 

[SM25T]

Overhaul by Road & Race ! Sort it ... don't mask it.

[jpbritten42]

They're the ones who built the diff....! 

[Wrightpayne]

What oil? Hypoid ep90 (ford stuff) can reduce noise with added lsd modifier where appropriate.

it does help if you're wearing ear protection !!

Ian

[SM25T]

Was it recent work ? Have you complained about it to them ?

[DJ.]

My ford (original, not remanufactured) diff whines at that speed, it was built by Road and Race, performs perfectly in every other way and sounds exactly like the previous Caterham diff that I changed because it whined. Oil made no difference to either diff.

It seems to me that on some chassis there is a resonant frequency that makes it louder at that sort of speed.

I wore earplugs for ages and even though it was quieter, they seemed to make the whine appear proportionately louder.

I've just changed to wearing a home made intercom headset based on a pair of Peltor Optime 2 ear defenders, and I have noticed that they cut the whine dramatically while making the lower exhaust noises seem louder which is much better

[jpbritten42]

Not sure what oil, but it was newly built diff was recently fitted by a well respected Caterham specialist who I'm fairly confident put the appropriate oil in. Will ask them what oil they put in though.

I have used ear plugs which do help, but I was wondering wether anyone had tried some of the lightweight sound deadening material that you can get these days. 

[jpbritten42]

Sorry SMT25, was typing when you posted your last response!

I don't think complaining will make much difference, they'll want to have it back to check it (which I understand) but that means another £400 for someone to take it out and put it back in again (properly), and they'll probably find nothing wrong.

It's got to the point where I'm considering other options, all be it ones that might not have been tried before...!

[jpbritten42]

Thanks for the feedback DJ. Your experience follows along the same lines as mine.

Intercom headsets do appeal, may try that after the sound deadening idea 

[SM25T]

You have mail ... in a minute.

[elie boone]

is it possible that if the shims (used to position the diff ) touch the chassis it's louder ? because they would transmit the vibration direct on to the chassis.

[Colin Cooper]

i could lend you SWIMBO for a bit if you want.......................................................

[Jonathan Kay]

Good luck with the project.

What materials are you considering?

How about using a sound level app on a smart 'phone to document the effects? Reviews and recommendation.

Jonathan

[revilla]

Following elie boone's comment ... isn't the Sierra diff bolted rigidly to the chassis anyway? In which case I would think most of the noise and vibration will be going straight into the chassis and trying to soundproof the boot would be fairly futile.

[Alan Reeves]

Interesting comments. I changed my quiet diff last summer for a taller one but only on the basis that it was not going to end up noisey .

R n R refurbished  one for me and assured me that it would be fine. Unfortunately it was not but I thought it was a resonance rather than noisey diff. R n R replaced with no issue and the next one was fine, I have no complaints re their service.

 

[jpbritten42]

I must be honest and acknowledge that my assumption is that the crown wheel & pinion is the route cause of the whine but it could well be other factors like shims or alignment. I'm fairly confident that the diff is aligned correctly though but maybe the shims necessary to align it are a factor.

I think the reason for me exploring other solutions is that people have chased the cause of the whining noise and given up. Changing to a different brand of diff oil may be a temporary solution but as it's only done a few hundred miles since the replacement R&R diff was filled and fitted by a well-respected Caterham specialist I'm not inclined to change it.

For what it's worth it's just the whine at a constant speed I'm looking to address in some way, I don't actually mind the clonks at low speed and backlash when decelerating.

If I can just reduce the whine my car would be perfect (for me!).

[Wrightpayne]

Andrew,

there are 4 metalastic bushes in the chassis, similar to those on the front wishbones. I can understand how a large washer could bridge the rubber between the inner and outer metal parts of the bush and transmit noise - something to check on mine!!

Ian

 

[revilla]

Ian,

The diff being one of the few bits I haven't had cause to pull off my car (yet), I hadn't appreciated that. Thank you for filling me in 

Andrew

[jpbritten42]

I think Ian may well be referring to a potential cause, particularly on metric chassis like mine.

I spoke with Phil at R&R this afternoon and i'm inclined to agree with him that the metric chassis is the consistent factor in this issue although how I would resolve it if metal washers are necessary for alignment / mounting is beyond me.

I'll have a look underneath my car at the metalastic bushes in the chassis tonight.

As for sound deadening, it would appear so far that I'm the only person whose considering this. Which doesn't bode well...

Very grateful for all the input so far though, I'll do some more research and then experiment.. (with sound deadening!)

Paul

[thompster]

Paul, just to reassure you, I have a 2007 metric car -first of the metrics, near last of the ford diffs and have the same cruising speed whine as you. It only does it when hot but given they all do it I've never considered any sound deadening

[sjl1]

My 2017 360r bmw diff whines badly at 50 and i have just tried changing the oil to motul but alas to no avail. The transmission noise on these cars is frankly rubbish. I doubt there is anything substantially wrong with my car, have drive  a few now and they are all noisy.

Would be interested to hear if anyone has had success with sound deadening, the transmission noise really ruins the enjoyment of the car?

many thanks

simon

[StevehS3]

Perhaps I’ve been lucky but my 2006 imperial SV with Ford diff was a bit noisy and clunky but didn’t have a loud whine at a particular speed. My current 2012 metric chassis S3 with BMW diff is far quieter and less clunky but again doesn’t have much of a whine at all. Strange that some have it and others don’t. Perhaps it is a resonance and if so what could be changed to prevent it?

[aerobod - near CYYC]

If I can hear the diff whine in 4th on the overrun in my R400D, I forgot to put my earplugs in.

[gulf 1]

No diff whine in my 2015 Supersport R with BMW diff.No idea what oil is in it.

[Dave J]

there will be whine in 4th as it’s direct drive through the gearbox.

If the diff

is quiet for the first 6 or so miles then that because it hasn’t yet heated up and expanded, altering the clearances on the diff internals . As from the mounting bushes being the cause