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escort sport to rocket (Type E) conversion

pete tudor

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Having broken the second escort sport gearbox fitted to my 1985 live axle caterham, now fitted with 1800 Zetec, I am considering fitting one of Brian Hills modified type E gearbox.

I believe I will nedd to change clutch driven plate, propshaft length + splined yoke, speedo drive and modify gearbox mounting position?


Can anyone advise me what modified arrangement will be necessary for the gearbox mount. Is it just making an adaptor plate or does it require support member surgery??


Any advise gratefully received!



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I'm not an expert on gearbox conversions, but I thought the Escort sport box was reasonably strong, did you have the first one rebuilt only for it to fail again, or did you just get another second hand one?


I have considered converting to the old 2000E 3 rail type, but mainly to have the fascility to fit a light alloy bell housing to save weight.





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I fitted rebuilt gearbox after the first broke when crossflow (120 BHP)powered. This lasted about two years of sprints etc. The Zetec is puhing out about 160 BHP (Measured 138 at wheels) and has broken the box after two events! (Brian Hill reckined the escort sport box was designed for only apprx 100 BHP).


I am just concerned that I will not be able to easily make up an adaptor for the gearbox mount and have to resort to modifying the chassis cross member? (I don't really want to do this as almost all the modifications I have made to the car, albiet extensive(+expensive!), are theoretically reversible).


Thanks for your input.

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Strictly speaking the rocket box refers to a cortina type box fitted with a set of close ratio and stronger gears. But over the years the casing used to make a rocket box has become known as the rocket box to distinguish it from lesser boxes.


The cortina box is as used on the RS2000, the other box is as used on escort sports. A pair of small alloy spacers are used on the RS2000, they're about 25mm square and 50mm long. These bring the gearbox rubber mounting plate back about 25mm and down about the same. TAS sell them, part no 0469. On the Caterham you don't have this mounting plate, just the rubber block so you'd need to do the same, bring the rubber block back and down.


I would have thought an alloy plate bolted to the bottom of the chassis mounting plate and running back would do the trick and still be reversible.

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You may want to give Steve Perks from SP Components a call. He is a top gearbox bloke.


I am running a sport box on my xflow and have done for 11 years, my car is now showing 140 at the wheels and as yet I haven't had a problem with the box (fingers crossed)


Another option is a straight cut box, the internals fit inside the sport casing.

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Glad to have some reassurance from Casbar, I'm running 1800 zetec on Z002 cams, 40 dcoes and my escort sport box is OK so far...


Road use only, and not rolling roaded, so actual output unknown.



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The Mk 1 RS2000 box, which has an alloy bellhousing and does use the Mk 3 Cortina gearbox case is a different length from the gearbox mounting and the front face of the bellhousing to the Escort Sport gearbox which has the integral bellhousing. The Rocket box is about 2.5 to 3" longer.


The spacers that are used to adjust the position of the tailshaft in the Mk1 RS2000 are theer to incline the engine backwards so that the Pinto top hose clears the radiator they don't deal with the difference in length.


The type 49 shell used on the Escort Twin Cam, Mexicos, RS1600 and RS2000s has the gearbox mountings in the tunnel and the hole for the gearsitck in a different place to the 1100/1300 standard shells.


The other difference is that the Rocket box is also wider where it enters the tunnel mouth.


I have an 89 short cockpit car with a Sport gearbox and I tried to fit a Rocket last year. I needed to do three mods.


The first was move or extend the gearbox mounting platform in the chassis to mate with the new position for the gearbox mount.


The second was to modify the spaceframe to allow the wider box to fit in the tunnel mouth.


The third was to shorten the rods in the gear linkage as the gearlever moves closer to the driver.


In the end I decided not to bother and carried on using the Sport box with a 160BHP Twin Cam. So far I haven't had any problems.


There is a Quaife kit for the Sport box and I plan to fit one later this year.


Some of the later chassis are "universal" and have mountings for both Sport and Rocket boxes.

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Thanks guys.

I think you have conviced me to stick with an escort sport box for the time being - otherwise I will spend another summer modifying the car and missing out all the events!!!

Thanks again folks, your comments much appreciated as always.

Pete Tudor.

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Other than the gear box problems, how do you like the zetec conversion? Is it worth all the trouble and expense?


I know you had a very nice X-flow which John Bigler exported to the U.S. (sorry about the complications) and should have a grasp of the pro/con of this project.







P.S. Your engine has a good home with John and I expect to see it on the road soon.

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I carried out this conversion on my car back in 94 and it was very straitforward. The main difference was my car was a 92 de-dion chassis and I used a long input 4 speed Quaiffe pro box and Caterham 5 speed prop. With no tunnel floor fabricating and fitting a mount was easy, I fitted the engine and box and with everything in line I simply made one from card and had it folded in metal at a place in town and bolted it to the chassis and 5 speed mount. With no chassis down the tunnel you will need a larger plate to spread the load and with the tunnel floor access will be more difficult but its only skinned knuckles after all. Clutch drive plate was 5 speed, the speedo cable was off the 4 speed sport and I used the speedo drive from the doner box, luckily the speedo was reasonably accurate. Try and locate an alloy bellhousing, it saves approx 6 kilos.


As mentioned above there is a Quaiffe kit for the 4 speed sport box, I had one before fitting the rocket and it was an absolute delight, very quiet for a strait cut box and from experience I know they will handle 180 hp x-flows OK. The only reason I changed was I also knew that they would not handle hillclimb starts on 8.2 inch rear sticky slicks without becoming a kit again. Well worth considering as they are a direct swap.




PS I now have a BGH 5 speed and I am delighted, have you considered fitting a 5 speed, there will be very little (or no) extra work but they weigh a ton.

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