Sound deadening for diff whine

[p.mole1]

I  had no noise from my old diff and I have have just rebuilt one so I was worried about noise but it's just a quiet as the one it replaced. 

I'm guessing if it hasn't been centered properly in the chassis with the correct amount of washers you can get metal to metal contact which will transmit noise. The bushes are very small.

[Tom_Arundel]

Caterham do a stick on carpet kit that helps if you have bare panels.

I adjusted the crown wheel in 6 notches and use Redline heavy shockproof oil...silence!

Mmm...I can hear every bird that sings as I go by and every other rattle in the car now.

The diff gets very hot, due to its hidden position and reduces the oil viscosity... an air scoop will help but that`s another story.

[sjl1]

Thanks for the feedback, i will take a look at the bushes but doubt its going to fix things, these diffs need to be bolted in pretty tight

think i will try some sound deadening and use the carpets as template for the rear panel behind seat and inside the boot, possibly also transmission tunnel, suspect this will make a big difference

[7 wonders of the world]

Its not about the final drive being bolted in tight more the transmission of vibration ie noise via metal to metal contact as using spacers washers with the wrong OD bridges the insulation rubber in the bush.

[Jim 123]

Simon, when you say that you get whine at 50 mph it is a bit hard to interpret what you might be encountering in order to assist.

Is the whine only at 50 and do you drive through the whine by increasing or decreasing road speed? Does it occur in all gears at 50? Do you still get the noise within the same road speed range with the car coasting in neutral? Does the noise frequency vary when you are on or trailing the throttle? Have you noticed the whine beginning within a rev range regardless of gear?

[sjl1]

Thanks Jim

whine is speed dependent and comes and goes with load and speed, worst at 50, although it never really disappears.

Going on the throttle or coming off makes it reduce, worst on a steady throttle at 50 on the A2 (which has average speed check)

Not gear or rev dependent, pretty certain its the diff and this seems to fit with others experiences of whining at a particular speed. Had the car from 500 miles and its  now 2500 and noise has definitely got worse, which suggests diff bedding in rather than bolted in wrong? (Its a bmw titan diff in that diff cage adaptor)

the mazda gearbox also rattles when coming off load and on overrun but this isnt so bad, have driven two others with similar characteristics 

i will take a look at spacers to see if this might be the problem but suspect its a difficult job to replace them, very hard to reach. Sound deadening does appeal because transmission is just so very noisy.

This is my third caterham and the one with the worst noise. I wouldnt mind if it was just the engine! (I built a tiger 6 with an xflow in 95 and the noise that made was amazing, noisy doesnt begin to describe it, brilliant)

[SM25T]

Lift the boot floor out ... makes access easier.

[Downlands]

Hi

Just resurrecting this thread as I'm considering the same source of action to reduce the diff noise on my 2007 R400 Duratec.
 

The car has been serviced over the years by a number of Caterham specialists and when I've commented on the diff noise, they have all said there's nothing wrong. 
 

I can tolerate the noise when going aero as I use ear plugs but when the full screen is on, it's very intrusive and makes conversation difficult, and it gets worse when the car is warmed up. Diff oil was changed by Caterham in Jan when it was serviced.

So I'm looking at the insulation route.... Just wondered if anyone has tried adding noise insulation on the bulkhead and boot floor and did it help?
 

Thanks

Tim

[7 wonders of the world]

On that year yours will have the Sierra final drive assembly.. have you considered getting it correctly rebuild..?

[SM25T]

This suggests you use no hearing protection when you drive with a full screen. You should protect your hearing. Everything is producing a lot of noise .... not just the diff .... wind roar, tyre noise, induction, exhaust, engine, gearbox. Consider using ear defenders with an intercom system if you have a passenger.

[Alan Reeves]

The noise scenario goes on. I had a quiet diff in a CSR but , nearly foolishly, had it changed to a much higher 3.14 ratio .

Great for the power and more relaxed for touring but...it had a serious resonance ( my interpretation) on a slightly trailing throttle between 50 and down to 35 mph. Nightmare as I was about to set of on a 2000 mile italian trip.

The well known expert company I bought it from were aghast and sorted it on my return ( thanks ) and the result was back to a nice quiet diff.

My current BMW diff in a Duratech car is absolutely fine . Neither situation had a LSD .I dont think its necessary to live with the noise and pop it to R and R or at least ask their advice.

 

[Rich Goddard]

Read this and other similar posts with interest for opinions & advice.

I have a loud diff whine on my (new to me) 2015 Supersport R. Understand the source is the crownwheel & pinion  

Just before I took delivery of it in February R&R had removed the knackered Titan LSD, overhauled the diff with new seals & bearings and fitted new Tracsport LSD unit. I love the LSD unit, the car feels very well planted! No issues with that. 

Should say I don't mind mechanical noises - all part of it in my opinion, but if there's an easy fix to reduce the pitch and volume of the noise a little I'll try it. 

Steve Perks of SPC/Tracsport fame suggested trying Redline Shockproof oil.  Have others tried this with success? Does it require friction modifier additive too? 

Also read in this thread about oversized spacer washers bridging the diff-mounting rubber bushes and transmitting resonance direct to the chassis.  Has anyone positively determined this as being a cause of amplifying the noise? And if so, a fix?

Cheers, Rich. 

[Tom_Arundel]

As I said earlier, I did all the carpet oil and C/W adjustments to good effect but also I ran a long 1/2 " drill through the top diff mountings because they are 2-3mm out of line when new. Many new builds hammer the top bolt through which preloads the rubber bushes.....just saying!   

50mph whine I think is a resonance in the prop shaft....I`m considering shrink wrapping it! 

[Rich Goddard]

Reply to #38

Thanks Tom. 
So it sounds like the CW adjustment and Redline Shockproof helped, but didn't completely nail the issue if you're still considering other measures. 
Can I just check please....did you add LSD additive to the Redline Shockproof as well?

cheers, Rich 

[Speedtrip]

I must have this wrong, but I thought fitting the Tracsport diff was the option to remove the unfortunate whine from these cars.

My 360R has howled like a banshee since new and I've been planning to ditch the Titan in preference for a SPC unit at some point.

[7 wonders of the world]

LSD noise usually knocks and bangs in the case of the Titan, leading to likely failure and whine induced by the reused 'selected' and / or badly set up CWP are often mistaken for each other.

They are two seperate components with entirely different tasks who reside in the same housing 

[Dave Hardcastle]

#40 I had a Tracsport LSD put in my Seirra diff by Steve Perks. The crown wheel/pinion still makes a lot of noise, as it did before the replacement.

I tried the expensive Redline Shockproof style oils and, if anything, found them noisier than standard Ford SAE 90 rear axle oil.

Hope that helps someone

[ScottR400D]

As said, it's the CWP that gives the whine. Some cars don't have any significant noise, some do but it can be adjusted out and some never seem curable. 

I have spoken to a few people who've had unbearable whine and adjustment by the best in the business hasn't cured it. Perhaps a  whine caused by poor set up causes damage that then perpetuates the whine.......?

Also as said, the Tracsport simply eliminates the grunting and groaning typical of the Titan. It also functions better IME and lasts longer. 

[Nigel B]

I'd agree that a poorly adjusted crown wheel & pinion can cause damage.

I fitted a Quaife ATB to my previous Seven, a live axle car. I got the local garage who did my MOTs to fit the Quaife, but they didn't get the adjustment of the CW&P quite right & it developed a whine that got louder over a few hundred miles. Prior to getting the Quaife fitted, it was pretty quiet.

I took the diff out again & sent it to Road & Race, who re-adjusted it.

When I refitted it, it immediately sounded quieter, but over the next 500 miles or so it got progressively quieter still, until it had no discernible whine at all. 

I can well imagine that if I hadn't had the CW&P re-adjusted quite promptly, it could have caused permanent damage & a permanent whine.

[Rhys Mann]

Ive installed killmatt on mine and although heavy has made a world of difference!  Id rather less noise personally

[Britspud]

On 01/06/2023 at 16:41, Rhys Mann said:

Ive installed killmatt on mine and although heavy has made a world of difference!  Id rather less noise personally

Hi Rhys...interesting. Did you drive the car/experience the noise before you installed the killmat? Or was it installed at build stage? I'm just getting to the carpet install part of my build, and have been considering putting some deadening mat on the bulkhead and boot floor. 

Thanks,
J.