Escort 5 Speed Gearbox Conversion

Kris Bubendorfer (c) 2000

The Type 9 Sierra 5 Speed Box

This article is based on my experiences in converting two Kent Xflow engined MKII Escorts to use the 5 speed Type 9 Sierra gearbox. There are several reasons why this conversion is desirable - it's not too hard, the box looks similar enough, it is stronger and it has the same shift pattern (plus 5th of course!).

The Clutch Pilot Bearing

The Bellhousing

1. Get a backplate from a Pinto powered Cortina. This will need to be modified as the rear crank seal housing is much larger on the kent engine. So simply cut out around the center until it fits your engine. This is the easiest and therefore the best solution.
2. Cut and weld the section of backplate through which the starter mounts so that it matches the Sierra bellhousing (this isn't too easy).

On no account should you simply discard the backplate - firstly that will let lots of crud into the clutch, and secondly it will move the clutch and flywheel several mm closer to the engine. If it wasn't needed Ford would not have spent the money including it.

The Clutch

Another suitable plate was also used in 2 ltr Aussie Escorts and can be found under the number RXXXX - but here in NZ that is a a bit unusual and costs $$. What I eventually found was that the Hillman Avenger (1500cc) has a suitable plate and as befits it's humble origins, is very cheap!

There is another method which is a good idea if you need your flywheel skimmed due to rivet damage, or you have seriously upgraded the power of the 1.6 Kent engine. You can get the Escort flywheel skimmed and redoweled to fit the larger 8.5 inch Sierra/Cortina pressure plate - and it fits, just. This means you can now use the larger Sierra clutch plate, but you should splash out on getting this new pressure-plate/flywheel combination balanced. I used an 8.5in Cortina pressure plate and not the Sierra one - so you should double check clearances etc. if using the Sierra item.

The Driveshaft

The Transmission Mounts

You now need to fabricate some alloy lowering blocks to place between the moved escort mounts and the original Escort crossmember. If you are in the UK, go buy some RS2000 blocks from almost anywhere. If you are in NZ or some other RS deprived locale, you will have to make them yourself - I used 30mm x 30mm Aluminium bar. See the figure for the dimensions of my blocks.

You also need to cut off the corner at 45 degrees to clear the tunnel, the next image shows this in a (not to scale) cross-section.

These are then bolted to the relocated mounts with 4 cap screws (allen keyed bolts) with a 12.9mm diameter head. You now put the gearbox cross-member on the box and line it up on the lowering blocks. Use a center punch to mark where the 4 cross-member bolts should go, and then remove the blocks and drill (6.8mm) and tap them with M8 x 1.25 threads. I have not given the locations of these final holes so as to allow for variation in the final mount positions.

Here is the view from underneath my car after showing the new mounting blocks. There was a small drop when the jack was removed - due to compression of the mounting rubber. To compensate I will remove the blocks at a later date and shave around 5mm from their 30mm hight.

I also suggest you don't fit the original bolts as they are likely to damage the soft aluminium threads in the blocks.

The other way to do this is a bit yuck, but very easy and really needs no welding at all. Remove the old Escort mounts and box crossmember, and then use the larger Sierra box crossmember (seen above) and mount this with bolts through the floor. I suggest you use large washers or weld in strengthening plates to prevent the bolts mangling the very thin Escort floor.

The Transmission Tunnel

The Gearstick

In the CF article they simply lop the top of the transmission tunnel off and weld on a new plate with a gearstick hole 2-3 inches further back, see below. I think this is a horrible idea, as you lose the rim that the gearstick gaiters mount on, which lets in noise, gases and crud.

As an alternative, you can remove the hole from the top of the tunnel and fabricate a pannel to put it in the new location - however, it is a bit small for the Sierra gearstick mounting. I used, belive it or not, the transmission tunnel cover from a 1966 Wolseley 6/110 - somewhat reshaped of course. The Escort enjoyed the BMC steel, and it looks good as you can see in the photo. I'm sure you could adapt anything with a larger gearstick hole.

The Escort gearstick gaiter will not fit the larger Wolseley hole, so I cut the Wolseley and Escort gaiters and glued them together with Super Glue - it works.

If you don't like the new gearstick position, you will have to cut, bend and weld the Sierra gearstick to get it closer to where you want - there is no other solution. Those with eagle eyes will see that this is exactly what has happened to my gearstick - it is considerably shorter and straiter than the standard stick. You can also get a quick shift kit from the UK if you want a snappier but nosier change.

The Wiring

The Speedo

As for speedo accuracy, using the rev counter as a guide - the speedo was reading almost exactly 20% over with the 4.125 diff. That is, reading 60 at 50kph, and 120 at 100kph. I can live with that, as the closest that you can get with a diff swap is the 3.54, which is still a 6% error and would overgear the car.

I must find out what drive gears are around...

References

• The first place to look is in the October 1999 issue of Classic Ford, which contains an MKII Escort 5 speed conversion in their `how-to' section. This is a good issue for the MKII as it also features a comprehensive MKII tuning guide.
• If you're doing anything other than the conversion outlined above, the January 1999 issue of Classic Ford has an article on special bellhousings for mating various engine and box combinations.
• Also, the Kent Capri club have an article on converting various models of Capri - see http://members.aol.com/kentcapri/5speed.html.