5 to 6 speed gearbox for xflow

[mikes]

I have found this old thread here:

http://www.blatchat.com/T.asp?id=41476

on the subject, but wondered if anybody else had any thoughts.

On a recent trackday I definitely did not have the right ratios (for my driving anyway) and the choice is close ratio 5 speed or go to the 6 speed.

This thread suggests that I would use the existing bellhousing - is that right? I rather wanted an excuse to buy a lighter one 😬

Mike

[Peter T]

What diff ratio have you then ??

 

Carbon Components from K9 Composites

 

[rgrigsby]

I suspect if you have a 5 speed at the moment you'll have a 3.92 diff, if that's the case then a close ratio 5 speed will probably be the better option.

 

Otherwise if you fit a 6 speed and stay with a 3.92 diff the overall gearing is very very short unless you engine revs to 8.5-9k rpm.

 

BGH do some very nice close ratio 5 speed boxes and they will upgrade your existing box...

 

I've had a 5 speed on a 155bhp crossflow, a 5 speed on a 8.5k rpm steel crossflow and a 6 speed on a 8.5krpm steel, whilst the 6 speed was superb on track and good for comedy value on the road in terms of instant acceleration in any gear it got a bit tiring on longer runs.

 

Rob G

www.SpeedySeven.com

 

Edited by - rgrigsby on 22 Aug 2005 16:11:36

[Normans_Ghost]

If you go for BGH sprint setup (2.66, 1.75, 1.26, 1.00, 0.86 plus 4.44 diff) see if he'll fit a 6th gear as a higher geared overdrive. My ratios (above) are fantastic on twisty A roads but is tiring on the motorway with 5000rpm for 85mph

 

Norman Verona, 1989 BDR 220bhp, Reg: B16BDR, Mem No 2166, the full story here

[EFA]

Norm,

 

What you describe gives identical ratios as a 6 speed Caterham box witha 3.92 diff.

 

I'm fascinated as to how BGH can jsut add another ration though.... 😬 😬 *tongue*

 

If the Caterham 6 speed worries you in terms of ratio's, you can also get a 3.62 and 3.38 all of which will reduce the revs. Personally taking these longer diff ratios destroys the fun somewhat. 6spd and 3.92 makes your car quicker, and makes it feel much quicker!

 

 

[Peter T]

And a lot nosier too. 😬

 

Carbon Components from K9 Composites

 

[Normans_Ghost]

Arnie, I was after acceleration on the road. 150mph is fine but not much use over the Snake or Cat & Fiddle. Whereas overtaking someone in less than 3 seconds is of benifit. And great fun.

 

Norman Verona, 1989 BDR 220bhp, Reg: B16BDR, Mem No 2166, the full story here

[Mcalvert]

Mike - if you go for new ratios in a 5 speed box (I did last year with BGH) then you can always change the bellhousing for an Ali one. Probably the cheapest weight saving per £ you can do. I got mine from Raceline.

 

If weight saving is really a concern, you can also change the gearbox maincase to ali - either from Quaife, or I believe that BGH may now do their own

 

Regards - Michael.

[mikes]

Thanks for the comments.

I will try and find out what the diff ratio is.

It is a 1990 De Dion which now has a 150 bhpish RK built engine. I still use it on the road and so would like to try and keep it semi civilized for that, but what I need is (another!!) edge to beat the young upstarts in class 2 in the sprints

Looks like I will be investigating several options over the winter!

Mike

[Richard Price]

young upstarts in class 2 in the sprints

But Mark says he's moving class next year (but he said that last year as well)

 

Mike, try to select the events where you get 6 timed runs

 

 

[mikes]

Richard - it wasn't just that young upstart Mark that I was thinking of - I seem to recall trying to catch up with a red 7 with dodgy tyres on most occasions this year - mind you the gear ratios must have been OK at Loton 😬 😬

Mike