Transmission whine

[Gareth H]

Sorry if this has been discussed before, I have tried searching but the function seems a bit limited (unless I'm doing something wrong).

My 7 (08 CSR) has a really annoying transmission whine when the throttle is being feathered (disappears with no throttle or when you are starting to push on) I had a chat with Road and Race who had recently rebuilt the diff, their view was that this is caused by the engine being slightly inclined, and they thought that somebody in the past had made some spacers for the gearbox that remedied this.

Does anybody have anymore info?

Thanks G

[Jonathan Kay]

https://duckduckgo.com/?q=site:caterhamlotus7.club+transmission+whine

https://duckduckgo.com/?q=site:caterhamlotus7.club+gearbox+spacers

Jonathan

[JAL73]

I have noticed a similar noise on my 2020 420R SV with feathered throttle.

R&R also mentioned the Caterham spacer (see pic below) which I have purchased and is awaiting fitment.

Note the website says its for 5 speed 2013 onwards, so not sure if its appropriate for an 08 CSR? 

Im not sure whether the spacer will fix my issue as it might be unavoidable crown wheel and pinion noise. I guess it would be interesting to hear whether the diff whine noise is also experienced by owners with open diffs and plated LSD diffs alike, in which case it would imply the crownwheel and pinion is the source and might be resolvable by adjusting the backlash.

It might also be noise from the Titan LSD but i dont think it is because i get the noise when driving in a straight line when the LSD plates should be disengaged.

R&R also mentioned their special LSD oil blend they make (with friction modifiers?) which sometimes reduces excessive noise from plated LSDs, though I imagine if it reduces friction in the LSD plates it means your LSD is less effective than with a higher friction oil?! (please correct me if im wrong on this)
I noticed a lengthy thread here about how choice of diff oil can make a huge difference to diff noise.

Hope this helps

    

 

 

 

[Mike-360R]

I fitted that spacer during my kit build in 2020 as part of the engine / gearbox installation. I have a 360R with Mazda 5-speed gearbox and I've not noticed any transmission whine when feathering the throttle. I'm also considering changing the diff oil to the alternative spec designed to quieten my Titan LSD down a bit - will be doing that at next service.

[ScottR400D]

The engine inclination is a red herring. The Duratec is tilted downwards by a small amount to clear the hood but the diffs I've been involved in measuring are also tilted downwards, in some cases more than the engine. 

That doesn't mean that there won't be an alignment error but does mean that it would be worse were the engine horizontal. And if you do bring the engine more to the horizontal you then risk it touching the underside of the hood  

In any case the alignment is well within tolerance to rule out any effect from the UJ rotation, which is what is alluded to. 

It's common to get a light chatter in the conditions you describe rather than a whine, or even what some describe as a scream! 

I understood the spacer was more to do with stopping the Mazda box hitting the tunnel sides but have no experience of it  

"R&R also mentioned their special LSD oil blend they make (with friction modifiers?) which sometimes reduces excessive noise from plated LSDs, though I imagine if it reduces friction in the LSD plates it means your LSD is less effective than with a higher friction oil?! "

Correct. It deals with a symptom, it doesn't fix the issue. 

[Dave Hardcastle]

I have a 2008 R400D. When purchased it had a Quaife ATB fitted and had a considerable whine around the 3-4k rev area.

I had a Tracsport LSD fitted to the diff by Steve Perks, and I still have the same whine. I'm quite happy Steve set the crown wheel and pinion up correctly.

I've tried a variety of different diff oils, including a very expensive one, and none made it any quieter than Ford SAE 90, which I now use. If your diff doesn't whine, you're probably just lucky

[SamC]

Well, this is a well timed thread!  I was going to do my own on exactly the same subject (although my noise is on both feathering and overrun…).

I’ve uploaded mine to youtube here, how does it compare to yours Gareth?  (Note I’m leaning towards the diff to try and hear whether it is Diff or ‘box, but I’m pretty sure it is ‘box)

My car is a 2008 CSR260, 6 speed box with MTL oil (freshly re-built at R&R), Quaife diff with R&R’s oil (rebuild last year) and diff struts fitted.  The overrun noise has greatly increased between the diff rebuilt (noise wasn’t bad) and the GBX rebuild and diff struts being fitted (done together over the winter)…

I don’t think I have the spacer fitted above.

Sam

[ChrisC]

Based on your post, I would remove the diff bracing, on the assumption that it's not a massively involved job. The purpose  being to identify the winter change that amplified the noise.
That spacer is only for Mazda gearbox cars, so to relevant to your car.

[ScottR400D]

#7 I'm sorry to say it but that's sounds awful! It's reminiscent of my Titan/BMW after being rebuilt with sintered plates. But worse.......

Have you asked R&R what they think of it? 

[SamC]

Yes, I only recorded it yesterday pm (just got the car back), and have sent them the same link.

The microphone is right next to the transmission tunnel under the dash, but I'd say it's a pretty accurate representation of what it sounds like in the car.

Id be interested to hear if it is similar to Gareth's, although it sounds like it may be a different thing...

[SamC]

Just thought, I had a lightweight flywheel fitted at the same time! I bet that is contributing...

Sounds fine when heavily loaded (either accelerating or engine braking), it's only low load that's noisy...

[Gareth H]

Sam, mine sounds pretty similar, maybe a little more Stuka like! I'll try to get a recording.