Diff

[Mrp]

#25 When mine was rear ended a week after I collected it, it went back to Caterham to have the damage sorted.  I did a sneaky upgrade at the same time and got them to fit RBTB. When SWMBO went in it next she said its far more noisy than before is that because it went back to Caterham so use it as an upgrade opportunity  

[Dave Hardcastle]

I have a 2008 R400D I purchased mid 2020. It had a diff whine from the start. I had a Tracsport LSD fitted towards the end of last year, so I know the unit is functionally OK and set up correctly. It still whines.

I recently did some research on here and found the thread about oils. I'd initially filled the diff with Comma LSD oil. I changed it to the recommended Ford SAE 90. The whine now 'appears' to be in a smaller rev band, but it's still there.

I contacted Steve Perks and he said I could try Red Line Heavy (red) Shock Proof Oil. At around £26/litre and the fact I'd need 2 bottles, I haven't tried it yet, and not sure that I will. I use ear plugs anyway, and putting my foot down removes the whine

[Beagler]

Thanks for your comments Dave. Its a case of do I leave it or do I change the diff. If I dont change it I will always wonder if it would have eliminated the noise. The diffs sold by Oakmere are new and not reconditioned..

[GulfSeven]

My 310R with LSD and lightweight flywheel whines. It's done it from new. Could be gearbox though. Who knows? All normal according to Caterham.

[ScottR400D]

#28. The diffs fitted by Caterham are new, so yours is only 2 years old and an open diff? Barely run in. Bear in mind that this diff is used by BMW on a range of cars and they do t suffer from whine etc  at then they aren't bolted almost solidly to the chassis 6" from your backside!

What's the price of a new open diff? £2k+? Hell of a wager when the odds are it'll be no better; maybe a little different but better? I doubt it. 

You seem to be doing what lots of others have tried in  the past searching for what doesn't really exist. 
 

[Beagler]

£1260 about

[ScottR400D]

Yes, of course. It's £2k + with an LSD. 

I should have known! I bought one and had an SPC LSD fitted to it just last year! £1160 at CC.

Anyway, still a fair bit when the odds are it won't help, IMO, but I'm sure we'd all be interested to see if it does make a difference. 

[Geoff Brown]

After my Steve Perks (Tracsport) LSD overhaul I filled with Castrol B373 SAE90 GL5 LS oil (down graded from GL6 to conform with latest oil ratings). Steve commented that this was OK & as good as any other mineral based LSD oil.

Some times there is a discernible whine & some times not at certain RPM & speed when cold. When fully warmed up no whine at all.

Being a full mineral oil I intend to change frequently.

[Benton]

I've recently changed the oil twice in the last few months in my Sierra lsd diff.  The original oil was mineral based (make unknown).

I first tried Motul synthetic (the Caterham endorsed one) and then tried RTT mineral based oil.
I'm convinced the diff runs more smoother/quieter with the RRToil than the Motul stuff but then I don't have significant whine with my diff.

 

[Beagler]

I suppose I should ask "Who doesn't have a Whine" ?

[ScottR400D]

Good idea! I don't know, I can't hear for all the other noise and my earplugs!!

Actually I get low pitched 'gear noises' from my diff but not what I'd call a whine, or at least not a significant whine. I get chatter from the diff on light overrun and overrun noise from the gearbox. 

All that mixes with the induction noise and exhaust but otherwise the car's quite silent..........

[Beagler]

[Tom_Arundel]

crown wheel turned in.....redline heavy.......no whine 

[7 wonders of the world]

so what backlash are you now running Tom..?

[ScottR400D]

A good question. 'Crownwheel turned in'? Does that mean backlash reduced or what? How do you do that?

I know some diffs allow for backlash adjustment by adjusting the preload on the bearings but with the BMW it's a matter of adjusting shims isn't it? 

[Dave Hardcastle]

Further to my comment above, I tried the Red Line Heavy shockproof oil in the diff. As soon as I left the drive, I thought it was noisier. Unfortunately, I wasn't mistaken. Expensive experiment!

Refilled with SAE90 Ford oil, part number 1 781 300, bought from a Ford van dealer for £12 incl. Also changed the gearbox oil for Halfords 80W90GL4 as a belt and braces exercise. Diff and gearbox quieter, latter well worth doing. My car's done almost 20k. As I only bought it last year I don't know how long the gearbox oil has been in, or what it was.

Thought I'd post my results in case anyone else considers buying expensive Red Line oil

[aerobod - near CYYC]

Redline Shockproof oils shouldn't be used in most applications unless explicitly tested, the non-Shockproof oils they produce should be used instead. The high film thickness combined with high slipperiness of the Shockproof oils is problematic in plate LSDs and gearbox synchros.

[David_Long]

An understanding of what is generating the noise is worth a comment.

The classic diff whine is essentially generated by the oil being ejected in pulses from between the teeth. These pulses can resonate in the housing and the oil itself and are heard when they are in the audio spectrum. A change of viscosity will alter things, but picking an oil that doesn't create noise is not all good news. The high performance oils tend to be noisier as they do a better job of adhering to the surfaces. Redline Heavy Shockproof in particular is formulated to adhere and cushion contact areas. 

WRT the Ford diff, a lot of research and developments was done by Ford to create a quiet diff solution. The oil they specified was part of that solution. The compromises was to create an oil good enough for the job, but not one necessarily offering the best protection possible.

[David Brown]

The Ford oil is probably designed to last the life of the diff. Not suggesting that you shouldn't remove the magnetic filler plug to check/clean it.