Gearbox noise

[magnethutch]

Sorry about the 3 post with the same topic and no extra info, seems that the site was not being very phone friendly.

So, i am new to owning a Caterham i have had the car since December and its been making a strange loud noise when in 6th gear and coming off the throttle, grinding/crunching noise. It is now starting to make the noise in other lower gears. I have also found it hard to get the car into reverse with it grinding and crunching into gear also. This is now getting worse and louder. I have also started to notice that going into other gears it is starting to crunch also.

The car is a 2010 R300 with 28,000,

Thanks

 

Sam

[Jonathan Kay]

You've posted that three times... can I help?

Jonathan

[SM25T]

Did you buy it from a dealer or privately. If you have any warranty ... take it back quick !

[magnethutch]

Yes I purchased it from Caterham so still got a warranty until December. When it's cold it seems to select gears ok, just once it has been on a long drive it gets hard to select reverse. The noise in 6th gear is all the time caterham said it was just the diff and is normal in the 6speeds. 

[SM25T]

If it doesn't sound right .... don't be fobbed off with "they all do that sir".

[ScottR400D]

The diffs can be noisy and often seem worse in 6th because you are more likely to be on a lighter throttle and not loading the diff. Also the chattering is most noticeable when lifting off and will be even more noticeable in 6th because the engine braking effect can often be less at normal speeds. 

As for selecting reverse, if you just dip the clutch and try reverse it might well crunch because reverse hasn't stopped spinning and it doesn't have synchro. Try going into first then into reverse. 

If the crunching is in other gears, is the clutch disengaging fully?

[magnethutch]

That seems to be the same information as I was told by caterham with the chattering noise from the diff in 6th gear. After my next drive I will try going into first before reverse and see if that helps. Yes the clutch seems to be disengaging correctly, getting a CRB noise but it's not that loud, I would expect it to be normal. 

 

[ScottR400D]

My diff, 2015 R400, has a lot of chatter, always has had. Definitely appears worse in higher gears as I said but after a while I've got used to it and can manage the throttle to minimise it.  

Try this:

Drive down the road accelerating reasonably quickly and lifting off completely at about 4000.

Accelerate up to about 50 in 6th and feather the throttle to maintain that speed or slow very gently.

If you get the noise with the latter but not the former I would say there's a good chance it's 'normal' diff noise.