M & P Developments

Where it all started : Matt Venn

I have a 1990,4×4, Sapphire Cosworth and, a little while ago I had my gearbox re-built. The builder dropped the casings back to me to paint along with the transmission coupling (rubber doughnut), saying I needed to get hold of a replacement. At that time I thought it wouldn’t be a problem. Little did I know that getting hold of a second-hand item would be almost impossible – let alone a new item. Manufacturing of these items ceased 20 years ago, with the last of the stock being sold over 10 years ago. 

I made various posts and made lots of enquiries to various people/suppliers but to no avail.

It transpires that there are two types of doughnut. 1989-1991 used the old style – a chunky section with and internal, spherical bearing and seal. From 1992 onwards (which includes the Escort Cosworth), Ford installed a smaller item without the bearing. They changed the three-pronged yolk on the rear of the gearbox and the front section of the prop-shaft which now had the spherical bearing attached to it.

Different people offered alternative advice on how to use the new style doughnut with making modifications to the drive train. These included; cutting the spigot off of the rear of the gearbox, sourcing and fitting a later front half of the prop-shaft, etc, etc. Whilst some of these suggestions would work in principle, I didn’t really fancy chopping off sections of the gearbox, then trying to source a later, front section of the prop which would be subject to the usual “RS-Tax”.

I was getting concerned as there was no way I could put the old doughnut back on the car as it was likely to fail at any time. At the same time – I wanted to be able to drive my pride and joy.

Seeing my frustration, Peter Johnson contacted me to discuss the possibility of designing and manufacturing an adaptor that’d allow the new style doughnut to be installed as a direct replacement part without the need of modification or replacement of existing drivetrain.

Over the last few Months, Pete and I have mocked-up, designed, tried and tested various adaptors with the new style doughnut. The last prototype has been a huge success and has performed faultlessly on Pete’s 4×4 Cosworth. It has around 400bhp and he drives it hard. The car has also been on the rolling road, again, performing without fuss. If anything, the drive train feels more solid that usual!

In essence, this adaptor replicates the original doughnut which includes the spherical bearing. We did wonder if we could delete the bearing, but, upon having a bearing-less prototype manufactured, during testing, we encountered vibration from 30mph. This very expensive prototype is now a very posh paper-weight! But, if you don’t try these things, you won’t know. Besides, we are more than aware that, whoever buys these things will be installing them into their pride and joy – Just like Pete and I. We’re trying to keep these fine machines on the road – not break them!

If you are the owner of a 1990 to 1991 Sierra Sapphire, 4×4 Cosworth, the chances are your rubber transmission coupling needs replacing as it looks like this:-

The deterioration of the rubber can lead to complete failure of the transmission coupling, meaning the prop-shaft will come away from the yolk at the rear of the gearbox and, in some cases, cause catastrophic damage to the underside of the vehicle. 

The doughnuts are a serviceable item and should be replaced when worn or at intervals recommended by the vehicle manufacturer.

With vehicles manufactured from 1992 onwards (Sierra Cosworths and Escort Cosworths alike), a different, more generic style/make of doughnut was installed. To enable this doughnut to be used, Ford changed the three-pronged yolk to the rear of the gearbox and the front section of the prop-shaft.

There are various solutions to make the later style doughnut fit the earlier cars (1990-1991) which include, changing the gearbox yolk, cutting the spigot from the original yolk, fitting the later version of the front half of the prop-shaft, etc etc. All of which could cost a significant amount of money when you eventually source the parts you need. 

Here at M & P we have designed, developed, manufactured and tested a number of direct replacement, prototype spacers/adaptors which allow the later style (and readily available) doughnut to be used, without changing or modifying any of the earlier style transmission components.

The spacer is CNC manufactured from a high-grade, high tensile stainless steel by an engineering specialist whom has a passion for high power and sports cars. The attention to detail in it’s finish is as you would expect.

Set within the spacer is a spherical bearing that matches the original Ford component. This is enclosed with a seal to prevent the ingress of any foreign bodies.

Again – this is a direct replacement of the original Ford component, meaning installation is very easy, even for those less mechanically minded. Fitting instructions will be sent with the kit (spacer/adapter & new Bilstein rubber doughnut) and a video of the installation will soon be available on Youtube. 

The latest prototype has undergone a lengthy testing process on a circa 400bhp 4×4 Cosworth without fault.

After 500 miles of regular, hard driving, and even a rolling road session, the spacer was removed from the vehicle and thoroughly inspected for wear and damage – neither of which were present.

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The kit has been re-installed on the car to keep in on the road, which was the main objective of this project – two guys, trying to overcome a problem to keep their Cosworths on the road!

The spacer itself doesn’t come with any official test accreditation (British Standards and the like). It is JUST a spacer. A later style rubber doughnut comes with the kit. This item is manufactured by Bilstein and is used by many vehicle manufacturers on literally hundreds of different models, including BMW.

This being the case, unfortunately, we cannot offer any form of guarantee. A lot of time and money has been invested into this item in an effort to keep our own vehicles on the road along with many other fellow enthusiasts’ cars. This was conceived and executed merely as a personal project which we thought others should benefit from.

Contact Peter Johnson or Matthew Venn via Facebook

Peter – https://www.facebook.com/peter.johnson.16547

Matt – https://www.facebook.com/matthew.venn.581