6 speed gearbox, 2nd to 3rd changes and detent spring

[skydragon]

Although my car's 6 speed box works fine on the road, I've discovered I usually struggle to change cleanly from 2nd to 3rd during Hillclimb/sprint competition.

 

The problem is probably me more than the gearbox and it has been suggested that a stronger gearlever detent spring may help (??).

 

I had presumed this was a gearbox out job, but searching the archives I've discovered the sring is located behind a 10mm grub screw at the front left top of the gearbox casing (very good news)

 

I've order a new spring (stronger race spring) from CC See here

 

Any one any tips/advice on fitting or adjusting?

 

Edited by - Skydragon on 15 May 2011 22:31:56

[6speedmanual]

Check your spherical bearing too. Search in TechTalk.

 

Peter

[skydragon]

Spherical bearing is 100% ok and well lubricated already

[6speedmanual]

I just asked Caterham parts about this spring.

Apparently it makes the lever spring out of 1-2 plane harder, presumably to help it across to 3rd gear. However, the person I spoke to also said he believes that most people who had fitted it had subsequently removed it because it makes pushing the lever leftwards into 1-2 plane too stiff.....

 

P

[Adrian Williams]

Chris

 

I've seen this job done by Phil at Road & Race and as I remember it the grub screw you mention has nothing to do with it and the gear box was out of the car. The spring is about 20mm in diameter so wont be going through a 10mm hole anytime soon.

 

There is a halfway measure that involves adding a spacer to the standard spring if the 'race spring' is too stiff.

 

 

Adrian

 

Edited by - Adrian Williams on 16 May 2011 13:57:34

[Mark Durrant]

Chris

 

Give Phil Stewart a call at Road & Race

 

Mark

[I reply to every thread]

Quoting skydragon: 

Although my car's 6 speed box works fine on the road, I've discovered I usually struggle to change cleanly from 2nd to 3rd during Hillclimb/sprint competition.

 

The problem is probably me more than the gearbox and it has been suggested that a stronger gearlever detent spring may help (??).

 

I had presumed this was a gearbox out job, but searching the archives I've discovered the sring is located behind a 10mm grub screw at the front left top of the gearbox casing (very good news)

 

I've order a new spring (stronger race spring) from CC See here

 

Any one any tips/advice on fitting or adjusting?

 

Edited by - Skydragon on 15 May 2011 22:31:56

 

When you say that you struggle to change cleanly do you mean that sometimes you end up in fifth - That's my problem on my VX with a 6 speed - If I'm revving it to 7-8K RPM it often goes into 5th instead of 3rd?

[skydragon]

You are right chaps. the grub screw secured spring has nothing to do with the centring of the gear lever.

 

I spoke with Phil at R&R today and yes, the spring I need to replace is inside the box. He also suggested that the fact my gearbox's gate is not symetrical is not quite right either (lots more side throw from 3-4 to 1-2 than from 3-4 to 5-6). He also suggested that he can alter the internals to in effect give a wider gate and longer throw between gears, which, combined with the stiffer spring should make correct selection between the gears easier....I hope.

 

To be honest, if my gear selection problems are cured 100%, I don't care if the spring is stiff and it involves a load of effort to shift the lever accross. (I can do brute force very well). I am amazed (very disapointed) that the CC six speed box is apparantly so hard to use for fast gear changes (Llandow the other week, showed this for a number of competitors), by comparison my type9 5 speed box was a doddle to use. Grrr.

 

...So saturday AM gearbox out, Sunday PM 300 mile drive to Kent, Monday AM gearbox mods and full refresh at R&R, Monday PM 300 mile drive back home, Tuesday AM gearbox back in... what a waste of time/money/patience...aggghhh!!

 

When you say that you struggle to change cleanly do you mean that sometimes you end up in fifth

...or 1st, which is interesting bearing in mind I've just reached the rev limiter in 2nd... I don't quite understand how this can happen in a synchromesh gearbox.

 

 

 

Edited by - skydragon on 16 May 2011 22:07:59

[Jason Plato]

if your rushing the shift, no change to gate or spring will change that.

 

I realy like the stronger detent spring but you still can't rush the shift

[skydragon]

Understood and agreed Dave. I undoubtably need to slow down the cross-gate gear changes down and resist the temptation to try and 'ram' it into gear, in the heat of competition. When I tried slowing things down last weekend on the advice of others (thanks), it definately did improve things for me, but I still had a few times when coming out of corners and chnaging up from 2nd I ended up in 5th, despite trying to do a slow and steady change

 

We'll see when the mods have been done at R&R what effect they have on my gear selection success/failure (if any). I can't help but think at the moment, with the current setup on my car, that it is just too easy to select the wrong gear when going 2nd to 3rd, when on-track and coming out of a bend, pulling G.

 

What is interesting to me is that some cars/drivers at our competitions do seem to miss 2nd to 3rd changes on occassion, whereas others appear to have no problem reported. This doesn't appear to correlate to driver skill....so, what is the delta between those who do and don't ?? I even noted one car at Curborough which didn't even have a working detent spring...and he certainly had no problems whatsoever!

 

 

 

 

[6speedmanual]

Having spend quite a bit of time helping people improve their driving, I've seen that many gearchanging problems are attributable to the way the knob is held.

 

It is often gripped too tightly from above or from one side. Sometimes in the palm of the hand, sometimes with the fingers, even with the tips! But the main issue is grip.

 

The method I have worked with and advocate is cupping the hand around the knob to guide it in the direction you want it to go. The fingers then wrap gently around in which ever way they naturally fall. This should be just enough to stop the hand slipping off or bouncing off on a bumpy road.

 

This may sound a bit obvious, but if it is not already a muscle-memory habit, it can take a few thousand miles of concerted development and practice to get right. It involves far more wrist work and rotation of the forearm than one might imagine.

 

However once perfected, it it there at you service for nice fluid gearshifts. It works best/easiest with 'boxes with bias springs but it is also good for non-bias gearshifts.

 

Enjoy.

 

Peter

[skydragon]

Quick update;

 

I took my gearbox along to Road and Race for a full rebuild and service. Whilst there Phil increased the power of the detent spring by fitting a spacer in the internals of the gearbox. He also altered part of the gating mechanism to get the throw of the gearlever more equal. During the service, he replaced the synchro on 3rd gear as it was very badly worn.

 

In addition I replaced the CC 'ball-type' gearknob with a alloy 'tower-type' gearknob a friend machined for me, this adds approx 3/4" inch height overall onto the gearstick and makes the gearknob easier to 'feel' and move.

 

These things combined seem to have made a big difference and it's now far easier to select 2nd to 3rd correctly. At Gurston down Hillclimb there was plenty of 2nd-3rd-2nd shifting and I didn't miss a single change.

 

The 'tower-type' gearknob in itself makes a massive difference,, as extending the leverage of the gearstick by nearly an inch, makes it easier to feel and select the correct gear. (fwiw - It's an easy mod to try changing gearknobs if you experience gearchange problems).