420R Clunky 3rd

[Andy Mac]

Hi Guys.

This is my first tech post in a 17 year absence, so be kind.

I have recently bought a 420R with Caterham 6 speed. Going up the box, it is clunky going into 3rd and only 3rd. It always goes in, but not smooth.

No issue on the way down. I have bled the clutch and adjusted the pedal to give excessive travel, but no improvement. 

Ant ideas? Any thing else I can try without striping the gearbox and replacing the synchro?

 

[SM25T]

Does the 6 speed have the same issue as the 5 speed .... the spherical bearing at the base of the shift lever can get dry and seize. Pull the gaiter away and trickle or spray some oil down down the side of the lever. Can work magic.

[David_Long]

These sort of things are always subjective. If it's a 'clonk' (just in 3rd) but always goes in to gear, then I doubt anything serious is about to happen, and probably not a gear selection problem. 3rd gear is at the rear of the gearbox on a spline (rather than being a machined part of the layshaft) and examples of the retaining bolt loosening are known, but rare. If it continues to trouble you, then think about investigating it further and an overhaul at Road and Race may be an idea, particularly if the car has done high track miles.

[John Vine]

Re #2:

I imagine your 6-speed has the Quickshift lever.  If so, the spherical bearing doesn't require lubricating as it sits in PTFE or similar.

It may not be the problem, but it would be worth checking the plastic saddle on the selector shaft.  Wear here can affect the precision of the gear change. 

Have a look at this Guide.

JV

[timb2117]

Hi Andy, I have had a few issues with going into 2nd on my box and from this amazing site and the knowledgebase of members I have finally gone through various options and ended on Redline MT-90 gearbox oil, (hot climate) its not totally fixed but way way better until I can get around to gearbox rebuild.

From memory Redline MTL was better for chillier places like UK:)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

9

[SLR No.77]

As an alternative view on MTL, I swapped back to standard Ford gear oil in my 6 speed and it's now substantially quieter which can only mean less component wear. The shift to second gear is not as slick but only in the first minute or so of driving after which the changes are perfectly fine as it gets a little heat in it.

Stu.

[Wrightpayne]

Stu,

have you got the ford part number for the gearbox oil? I'm a bit Okey Cokey with MTL - had it in couldnt tell any difference, then Comma and now back to MTL!

I have ford GL5 oil in the diff (Ford Ranger still uses it!) 

Ian

[SLR No.77]

Sorry Ian, I didn't change it, I had it swapped when it was MOT'd. Much easier done when there's the facility to raise the car up high.

Stu. 

[7 wonders of the world]

Gear lever is the same for the Type 9 5 speed and Caterham 6 speed. 

There is a an upgraded spring for the gates - SPC make their own as the stock is too soft and the race version too stiff - sounds a bit like Goldilocks    along with a good few other tweeked parts for the 6 speed.

[Andy Mac]

Thanks for all the advice guys.