Gearbox advice, please - R400D, 6-speed

24 posts / 0 new
Last post
John Vine
John Vine's picture
Offline
Last seen: 50 min 37 sec ago
Joined: 17/04/2014
Gearbox advice, please - R400D, 6-speed

R400D (2008), 6-speed box, 48K miles.

Something odd happened with the gearchange during the 30-mile trip to my MOT yesterday.  

When I went to change down from 6th to 5th, the gearlever became very reluctant to move, and when I pressed on the lever, I could feel (hear, even) what seemed like poorly meshing gear teeth.  It was as if I was attempting to make a poorly-synchronised clutchless change.  

After a couple of moments, I succeeded in changing down, and further downchanges (5th to 4th and so on) were ok.  Up-changes were as normal.  The same problem occurred just once more during the outward journey.

Nothing untoward happened on my return journey, with all up and down changes silky smooth as usual.

The box is the original, has been faultless since new, and hasn't been reconditioned in any way.  I've yet to check the oil level, but there are no leaks and the car was serviced by Millwoods 350 miles ago.

Could there be a problem of some sort with the synchro mechanism?  And if so, why would the box behave impeccably on the return journey?  

Any thoughts, chaps?

JV

Jonathan Kay
Jonathan Kay's picture
Online
Last seen: 2 min 38 sec ago
Joined: 17/04/2014

Could that be a problem with the selector mechanism? That would be easier to inspect and cheaper to fix.

Jonathan

Wrightpayne
Wrightpayne's picture
Offline
Last seen: 21 min 34 sec ago
Joined: 17/04/2014

Sticking clutch possibly? 
 

could do an oil change and see if any bits come out (6sp has a drain plug)

Ian

elie boone
Offline
Last seen: 32 min 42 sec ago
Joined: 17/04/2014

Could it be the gearlever ball joint that has a lack of grease ? you can't reach it from the underside unless you have very little hands but if you undo the gear knob and pull the gaiter out you can about just fit the grease gun head trough the top of the gaiter to grease the ball joint. this would save to take the tunnel out.

7 wonders of th...
Online
Last seen: 40 sec ago
Joined: 17/04/2014

The spherical joint on the gear lever could cause a stiff shift however this would have no influence on the grating noise heard and felt.

so assuming the clutch is clearing correctly...? then this is a syncro issue, sticking or worn ring or worn gear in the mainshaft which permits it to cockle a slight amount and not disengage or worn dogs on the hub or broken blocker spring.

I would recommend tomorrow morning you call Steve Perks at SPC, he has redesigned quite a few 6 speed parts, after of course you've had a pee and made a flask and sandwich prior to calling.... Rofl 

https://www.tracsport.com/

 

 

John Vine
John Vine's picture
Offline
Last seen: 50 min 37 sec ago
Joined: 17/04/2014

Thanks for the feedback, chaps.

Could that be a problem with the selector mechanism?

I suppose it could be, but everything worked perfectly on the return trip, so for the moment I'm not suspecting selectors.

Sticking clutch possibly? 

Clutch seems fine, and engagement is smooth. There's no graunching when selecting (non-synchro) reverse, so I think the clutch is ok.

could do an oil change and see if any bits come out (6sp has a drain plug)

That's a very good idea.  I'll do that.  It occurred to me that there might just be some rubbish in the box that had somehow got in the works.  I'm assuming the drain plug is magnetic?

Could it be the gearlever ball joint that has a lack of grease ?

I don't think so as the lever action was as smooth as silk, even when the problem occurred.

I would recommend tomorrow morning you call Steve Perks at SPC...

Thanks for your diagnosis, Neil.  I'm afraid you might well be right, so I'll do as you suggest.   I'll also ask Phil Stewart of Road & Race Transmissions.

More news later.

JV

 

Wrightpayne
Wrightpayne's picture
Offline
Last seen: 21 min 34 sec ago
Joined: 17/04/2014

Could of course be user not prodding the left peddle enough! I've done it a few times in my driving life!

But the next big question, what oil is going back in?

sjl1
sjl1's picture
Offline
Last seen: 1 hour 25 min ago
Joined: 21/04/2017

If this was a normal tintop obvious suspect would be clutch?

sforshaw
sforshaw's picture
Offline
Last seen: 1 hour 58 min ago
Joined: 17/04/2014

If the clutch or clutch arm starts to fail it becomes most noticeable with difficulty selecting 1st or reverse, higher gears are much less of an issue.

Stu.

Lotus Seven Club AR Working Group

The register for all numbered limited-edition Caterhams ....... www.thecaterhamregister.net ...... www.instagram.com/thecaterhamregister

John Vine
John Vine's picture
Offline
Last seen: 50 min 37 sec ago
Joined: 17/04/2014

...what oil is going back in?

Now, that's a good question. What do you recommend? 

If I could still get it, I would go for Ford's original "red" gearbox oil, as specified for the Sierras.  I used that in my 1.8K 6-sp and it was excellent.  AFAIK, the oil has been in there since build, and is Caterham's own brand (Comma?).  I guess the choice is between that and Redline MTL?

I really don't think it's the clutch.  There's no drag whatever when I select reverse, and other gear changes are generally super smooth.  There's no judder, slip, grab or any of the other nasty symptoms.  The entire clutch assembly (flywheel, driven plate, cover and slave) was replaced after my catastrophic clutch failure in France in 2015.

I think 7WotW has the likely answer, and I'll be in touch with SPC and Phil Stewart.

JV

ECR
ECR's picture
Online
Last seen: 2 min 32 sec ago
Joined: 17/04/2014

My first thought was a cracked synchro ring. I had a few before I went dog box.