Upgrading from a 4 to 5spd box

[Richard Gibson]

I have an 85' Caterham LC Supersprint. I recently upgraded my motor to 150hp crossflow. Now I find even more that first gear has come and gone way to quick. I have a friend who bought a 5 spd box from SPComponents and loves it. With them you can pick out your own gearing to a degree. Are there any other people who sipply boxes for the crosflow??

 

Also, what mods are serious. Propshaft (easy) Make new tranny mount (I have no Idea on this one, but there seems to be alot of area to work with???)

 

Are there any boxes by name I should avoid/or to look for??

 

Any and all advice welcome?

 

Many thanks,

 

Richard Gibson

Washington DC, USA

[The Stig]

There is quite a lot involved in changing to a 5sp.

Shaft, and some chassis mods I believe to get it to fit to your

car.

 

You can more easily choose the ratio of 1st gear for your 4 speeder. Depends a little on what it is. Most good gear box places... SPC included should be able to help. I assume you have the Escort type with bell housing and box as one.

 

The 4 speeder is lighter than the 5 speed box too!

[philwaters]

As far as I recall you will need to source:

5sp Box,

Clutch plate to suit - different input shaft on 5sp,

Bellhousing to mate to the new box,

30mm Alloy spacer (between the g/box and bellhousing),

Gear lever,

Propshaft work required,

Need to have a gearbox mounting plate fitted to your car (I presume you don't have the plate with 4 slots and one big hole about 12" down the tunnel).

As a result you may find you need different clutch cable, or are you hydralic?

 

Not a 5 minute job. I think I would go the route suggested and look at getting your 4sp fitted with suitable ratio's.

 

Phil Waters

2000 Zetec is in, waiting to start it up wink.gif

[Nigel Riches]

Richard, I had my 1982 Caterham modified to accept the 5 speed gearbox, but living in U.K. it went back to Arch Motors, however, if you try these links you maybe could get some info from your side of the ocean,

 

http://www.uscaterham.com/home.html

 

http://www.davebean.com/

 

The mod looked reasonably straightforward, the steel plates on the inside of the tunnel, where the gearbox mount is located were replaced with longer ones, the curved, square section tube that crossed between the front of the foot boxes was removed, the floor panel was relieved to allow the rear of the 5 speed box to fit back into the tunnel, a new gearbox carrier was installed as part of the tunnel side panel mod described earlier, the tunnel had to be removed, as did the floor skin, so a lot of de-riveting and re-riveting was involved, but all in all a worthwhile improvement, the 5 speed box I use is from a one man outfit, BGH gearboxes, in Kent, this has the following ratios, 1st 2.83:1, 2nd, 1.81:1, 3rd 1.26:1, 4th 1:1, 5th 0.85:1, these give the wheezing old crossflow a good range of cogs, S.P.Components 'boxes are available with some similar ratios I believe. hope this has given you some idea of the depth of engineering required, don't be put off, it's definately worth it, especially with a 2L Zetec, and you'll need to mess with the gear shift, prop shaft, possibly the clutch release arm, a spacer of about 1" between the gearbox and bell housing, so have fun, get those tools out and go to it, regards Nigel.

[Paul Turner]

Richard

 

I investigated doing this with my 88 LC Supersprint about 10 years ago. All the bits listed by Phil were easy to sort, it was only money after all and the clutch cable did not need changing. The main problem was sorting the tunnel and rear mount. The existing chassis mount needs removing (it fouls on the bottom of the gearbox casing) and a new one then needs fabricating and fitting. The mount for the 4 speed is raised above the floor about 1", the 5 speed is virtually flush with floor so no fancy folding is required but since there are no chassis tubes in that area to secure it to it needs to be secured to the steel plate that remains from the original mount. I was warned that the tunnel floor would possibly need trimming to give clearance on the much larger 5 speed box. I took the route recommended by Steve and Phil, I got a 4 speed sport box fitted with quaiffe ratios and it was direct swap. Smashing box providing you don't decide to put BDG type power through it. Speak to Steve at SPComponents.

 

Paul

[oilyhands]

Brian Hill at BGH Geartech produces excellent boxes with a choice of close ratios in 5 and 4 speed, details are here.

 

Dave

[Richard Gibson]

Thank you for all the help in this area. Id does sound like a bit more than an easy swap for sure. I notice many of you mention defferent first gear 'ratios', I was under the impression that changing those you ended up with a straight cut 'noisy' box. I don't want that. I wish I could put my old elan box in there. Or are there any other 4 speed boxes that will mate up.

 

As one mentions. I have the bellhousing and tranny in one piece.

 

So are there any other box options that are 4 speed?

 

Thanks

 

Richard Gibson

Washington DC

 

I bought a LSD from SPC....Steve is the tops.

[Nigel Riches]

In reply to your latest question about substitute 4 speed gearboxes, the far superior 4 speeder (type 2300, or more commonly, 2000E)from the Cortina Mk2, Capri 1600/2000 etc, probably not very common in America, is a good move, the overall gearbox and bell housing length is greater than the Escort 'box, but the gearbox mounting is only about 0.5" rearward from the one piece 'box ie, some swift work with a file, to make the holes in the steel part of the rubber mounting of the gearbox into slots, and Robert is your fathers brother, I did this mod prior to fitting the 5 speed, the bolts for the bell housing all line up, the spigot bearing is the same size, the cable operated clutch remained, the prop shaft had to be shortened, the selector mechanism had to be shortened, just drill through at a point further to the rear of the remote, this also improved the quality of the change, the clutch friction plate needed to be changed as the input shaft is a larger size, if you want to mail me off line your snail mail address, I can send you some copies of some very old

pages from C.C.C. listing the why's and wherefores of swapping these early Ford gearboxes, clutch requirements, dimenensions, ratios etc. regards Nigel in Noo Zillund.

[Paul Turner]

Richard

 

The 4 speed quaiffe sport box that I had in my car was by far the quietest strait cut box I have ever experienced, not OEM silent but in a seven with loads of exhaust, induction and wind noise it was barely noticable and in 4th it was totally silent.

 

The 4 speed rocket (OHC Cortina, Capri and early Sierra) is smaller than a 5 speed but some mods to the transmission tunnnel would probably still be necessary. I have fitted one in a de-dion chassis and there was acres of space around it comparred to a 5 speed. The mount is about 1/2 way between the sport and 5 speed positions (using a long input shaft), the bellhousing and clutch are as 5 speed and if you use the long input variety the spacer is the caterham one. Brian Hill does several helical ratio sets with long and short input shafts for these.

 

The alternative suggested by Nigel is interesting as a friend of mine had the 2000E box in his Elan modified by Brian Hill (BGH) with closer ratio helical gears. Give Brian a ring on 01580 714114.

 

Paul

 

PS I am a satisfied customer of SPC, BGH and Quaiffe