5 speed box replacement

[steve and casper]

Ivre been offered a type 9 (rocket)box which im considering putting in my 4 speed live axle 07 supersprint.Its off a westy.The ratios are different as follows

4 speed 1st 2.39 to 1/2nd 1.69 to 1/3rd 1.34 to 1/4th 1 to 1

Proposed 5 speed 1st 3.65 to 1/2nd 1.97 to 1/3rd 1.37 to 1/4th 1 to 1/5th 0.82 to 1

Apart from the obvious question as in Is this a straight swap?.It will help at the top end and give a longer first?,which would be of use in my proposed first season at sprints/hillclimbs.

Am I right in these assumptons and there any other points that i should consider before the transplant ??

Any help on this would be much appreciated as im a novice in the confusing world of Caterhams

Steve

 

 

[allen]

Not quite a straight swap. Yes the gearbox bolts up to the engine OK, but it's a longer box and the mounting is different -I believe someone provides a mounting conversion kit - mentioned in Low Flying and provides funds to Nuke The Leuke.

 

You may need a new mainshaft bearing in the end of the crankshaft .

 

You will need a new propshaft - gearbox splines and legth different.

 

Not sure if cluch driven plate needs to change - but wise to renew it anyway.

 

Box is also heavier - can't remember how much - but you can buy an alloy bellhousing 😬

 

If I've got anything wrong I'm sure another poster will point it out

 

I used to have a bit of software that told you how changes of gearing would affect the car - can't find it now ☹️

[JampJ]

Be careful, the box You need is from an XR4i which has a longer shaft than a normal type 9. This is required to put the gear lever far enough back. It also needs a spacer between box and engine, a different speedo cable is also needed as well as peviously mentioned parts.

Cheers John

 

JFDI

(Just F*****g Do It)

[Richard Price]

Steve,

It will help at the top end and give a longer first?

Yes and No respectively.

"Yes", a higher top speed (but you're unlikely to get into 5th on any sprint or hillclimb), and "No", a 3.65:1 1st gear will be a significantly lower (slower) first gear than you currently have!

For sprints and hillclimbs, your existing ratios would be better.

 

 

[steve and casper]

Many thanks to all responses to the gearbox swap question which has convinced me to stay put.Is there an easy 5 speed swap and spec whilst keeping a long first gear ?.Thanks once again to your quick response

Cheers

Steve

 

 

[Englishmaninwales]

Steve

BGH provide alternative gear ratios for the 5 speed, on exchange. Various ratio sets are available with a long 1st e.g. 2.66 1.75 1.26 1.0 0.84. For the effort in changing, I'd keep the 4 speed.

 

Malcolm

[steve and casper]

Malcolm

Conclusion reached on the basis of yours and others contributions.Thanks.Is this Malcolm from the track day ??

Cheers

Steve

 

 

[S47zz]

Did this swop in my 7 the 5th gear is worth having the 3.65 first gear though is useless. so yes the swop is worthwhile but make sure the gearratios are correct

I've just upgrade my 5sp box to a TranX S/C with the 2.4 1st gear, and closer ratio 2,3,4 & 5th

Sounds great too 😬 😬