Gearbox Conversions

[jamesabbatt]

Hi there, This is my first post and i just wanted to wish everybody a Happy New Year. I have a 1991 Live Axle 2.0L Zetec Caterham and im wondering about gearbox conversions? Im currently running a 4 speed quafe close ratio box and the reving when on the motorway is getting a bit tiresome. Has anyone out there done the 5 or 6 speed conversion and how difficult (and costly) is it to complete?

 

Any hint, tips or points in the right dirrection will be great!

 

Thanks for reading and i look forward to any reply

 

Jim

[rgrigsby]

Have a look at the section titled 5 speed conversion here. Probably a good starting point.

 

Rob G

www.SpeedySeven.com

[CanAm]

Top gear in the 6-speed is 1:1, the same as 4th in the 5-speed and no doubt the same as your existing 4-speed, so it won't help with cruising.

 

Alan

_{Machines were mice and men were lions, once upon a time.}

[jamesabbatt]

Thanks for the help!

[6speedmanual]

Welcome Blatchat Technical Mr Ablatt (appropriate name )

 

Worth having a play with a gear ratio calculator before attacking the hardware. here

 

Enjoy

 

 

 

6SpeedManual

*tongue*There's no such thing as too much BHP per Ton 😬

[Big Brother]

Hi James,

 

I did the conversion a few years ago and it tranformed my car and the type of driving I do.

I used to hate long journeys and avoided motorways like the plague.

 

Since fitting the 5 speed I've done 3000 miles in 2 weeks and 7 countries 😬

 

To swap from 4 to 5 or 6 speed, you will need to do the following...

 

If your car is newer than 1995, then you may have 2 mounting points for the rear gearbox mount.

If not, then you will need to modify the chassis. this is not as scary as it sounds as Brent Chicwick sells a conversion kit that moves the rear mounting point back by about an inch.

You may need to get a spacer to co between the bell housing and gearbox depending on the model of gearbox you get.

(the best standard 5 speed is the one from the XR4i, this has a long input shaft and better ratios)

You will need to change the clutch friction plate as the splines on the 5 speed are different from the 4 speed.

You will also need to get the propshaft shortened and the bit that goes into the gearbox changed.

This can be done by the Propshaft Clinic in around 2 days for about £100 including delivery.

 

Once you get into doing the job, it all becomes very straight forward and easy to do.

 

There are a few photos of my conversion here

 

Steve

 

 

SE7EN-UP!

---

_{Build a man a fire, and he'll be warm for a day.}

Set a man on fire, and he'll be warm for the rest of his life!

---

 

[patneale]

Hi Jim,

 

Lots of excellent advice here! Use the Gear Ratio Calculator.

I assume that the main use of the car is as a road car for fast journeys and not track racing, which is what the close ratio gearbox is designed for.

The 6 speed is a wonderful device (after about 30,000 miles when it is run in ), but is really only suitable for the track as too close ratio for road work. I made the mistake of having a 6 speed for my 2003 140BHP SV and have the same problem of only 19.2 MPH per 1000 revs so Motorways are slow to avoid excessive fuel consumption and noise. My K series is happy to pull 6,000 revs for miles,( on the continent ! ) but with ringing ears and alarming speed of a dropping fuel gauge not to be repeated often.

You need to aim for about 25MPH/1000 revs to get decent fast cruising and fuel consumption and only the 5 speed will get you near this. On more modern De dion cars a high diff is an answer, but with the 6 speed to get better cruising the first gear becomes too high for easy starts. What you really want doesn't exist from Caterham.... a wide ratio 6 speed with a spread the same or slightly wider than the present 5 speed.

Of course the better option is to treat yourself to a newer De dion car with a 5 speed and leave the present car to someone to enjoy in its present "racing " gearing!

 

HUGH ROBINSON

[CageyH]

Or buy a different type 9 box, sell the quaiffe on, and get the Long 1st gear mod done by BGH or SPC etc.

 

I run a long 1st SPC semi helical box on my K series, and I am quite happy with it.

 

Only dead fish go with the flow....!

[Englishmaninwales]

Happy New Year, James . Trade your 4 speed Quaiffe and fit a BGH converted 5 speeder, using the 5 speed conversion kit.

 

Malcolm

[SLR No.77]

Happy New Year James (Jim?) and welcome to BC

 

Stu.

 

www.superse7ens.co.uk..........the rebuild 😬

 

 

[Graham Perry]

Jim, as said above the 5 speed type 9 is a good gearbox but it really does need the higher first gear mod from BGH or the other vendors, even if you have the XR4i gearbox. If you can't get an XR4i box any other type 9 from a V6 ford should be okay as they all had higher ratios and the longer shaft as well.

 

The main seven type gearbox folks tend to be SPC, BGH and Road & Race trasmissions.

[jamesabbatt]

Thanks for all your comments guys and the advice, i`ve got a few options to explore now!

 

Thanks for the warm welcome too!

 

Cheers!

[Englishmaninwales]

James

Im not far from you, if I can help! When my car is back together again in a couple of months, you can try my BGH modified 5 speed (albeit with a K series engine)

 

Malcolm