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ZF 5 Speed Gearbox Development



The main header photograph shows a Series II interior, but with a leather console as per the Federal models and a manual gearstick. A gearstick which doesn't look like a standard 4-speed version.. an ECU is hanging from below the glovebox. What's going on?

In the Summer of 1966, A.B. Smith was requested to inform the ZF management of the Rover Company’s intention to purchase substantial quantities of their gearbox, provided that the noise in the gearbox which had been reported by our engineers, was eliminated. In the same entry, the Technical Director, Mr. Wilks, informed the Chairman that the financial liability on the cancelled P6B manual gearbox related mainly to the bell housing. Mr. Bromley added that the modifications which had been carried out had greatly improved the reliability of the P6 gearbox. Mr. Bacon gave details of the proposed changes top the clutch withdrawal which should give greater withdrawal clearance and lighten the pedal load.

In late 1966 the Chairman mentioned that he would like to see the manual ZF gearbox introduced on the P6B at the same time as the Automatic, if that was practicable. In January 1967, it was reported by Mr. Wilks that the engineer had not returned from Germany and was still working at ZF with their engineers on the noise and wear problems. A promise had been received from ZF that the Rover would satisfactorily met by the end of the month. 

During the meeting of the Rover board in April 1967, it was noted by the Chairman, W. Martin-Hurst, that the proposed fitment of this gearbox had been cleared with Sales and information was requested from Engineering on technical clearance in view of the comments expressed in the previous Engineering Report. 

In July 1967’s report from the Managing Director is was noted that a new manual gearbox design for the P6B car has been put forward by ZF for further consideration, and drawings of this were awaited. Initial discussions have taken place between Standard-Triumph and Rover on the question of up-rated gearboxes.

The next month’s report states that during testing two faults had become apparent in this gearbox, namely, the noise level and the difficulty of engaging gear when the box was cold. They were looking into another gearbox they had been offered but there was a strong possibility that they might have to drop the proposal for a ZF developed gearbox.

The next entry dates from March 1968, and it states that an uprated needle-roller type gearbox is performing satisfactory in an assessment vehicle as well as on a dynamometer. In the Technical Director’s report, it is reported that an uprated Rover manual gearbox is now available which, with some modification, might be suitable for use in the P6B car. However, it is noted, that at present there was no plan to use a manual gearbox, although it was probable that they might decide to fit one in the future if a suitable unit would be available. It could be that a five-speed unit produced by Jaguar would be made available to Rover, and that the same was under consideration. 

The next month it is noted that the uprated needle bearing gearbox had failed about half-way through its dynamometer test at 2158 engine torques. They were going to run the box at 2.5 Litre STI V8 engine torques, and they believed it would be satisfactory at those levels. From ZF, that same month, they received notification that their new gearboxes were almost ready, and Rover agreed to send a car to Friedrichshafen, where ZF would install one of their gearboxes in the vehicle and carry out the necessary work. Sadly, it’s impossible to confirm which car this might have been. It might have been JXC810D. 

For the P6B MK II, as the Federal 3500S was initially known at Rover, it was noted that aside from power steering and electric windows to be included as optional extras, that it would not be feasible to include a manual transmission option on initial cars, mainly because of the difficulty of meeting 1970 detox standards, even with an automatic transmission. 

In July’s Technical Director’s report, it is mentioned that the new Three Thousand Five fitted with the new ZF gearbox performs well and durability tests are in hand. The cost of this gearbox, however, is noted to be extremely high and the possibility of using the Jaguar gearbox was again being considered, all the while further tests of Rover’s own uprated gearbox were continuing. 

It is possible that at any point the assessment cars were cars from the P6B prototype programme. With the Three Thousand Five now in production, these cars were reassigned to various other programmes for which cars were needed. It is known that JXC810D, which later went to AE Brico, was fitted with a ZF 5 speed gearbox. JXC811D and JXC817D were also mentioned to have manual gearboxes, as noted by Brain Terry in James Taylor’s book. 

Rover efforts in 1969 were stretched between the 100” Station Wagon or Range Rover, the P6B MK II, the facelift of the P6B MK I, P8, P9 and preliminary development outlines for P10. It seems that the manual gearbox option for the P6B was put on the back burner a bit with no mentions of it until October, were it was noted that consideration should be given to the possible introduction of a package of fuel injection and a manual transmission combined. It must be noted that over the course of 1970, a few such cars were built for management personnel to drive and for endurance testing. It is not known what has become of these cars. In early July 1970 it was reiterated and a provisional introduction date of a manual gearbox model with fuel injection was set for ‘the early part’ of 1971, subject to the fuel injection assessment cars being built proving satisfactory. Later it was noted that a budget allocation was to be made to make modification to the transmission tunnel and the exhaust. 

In December 1970 it was noted that the car was performing very satisfactorily but if a few unspecified problems weren’t solved the 3500 EI would not be able to go to market. This ties in with the purchase order given by Rover to AE Brico around this time, and although a story for another time, it affirms the intentions that Rover had to introduce the 3500 EI in the Spring of 1971 on to the Home Market. It is essentially a Home Market S2 looking car, but with a manual transmission and most of the interior lifted out of the Federal 3500S!

In March, matters take a turn for the worst. AE Brico’s fuel injection programme was cancelled by AE, and the rights are sold off to Lucas leaving Rover, and many others, in limbo. Rover rushed the development of the manual car with carburettors and introduced it as the 3500S in the Summer of 1971. They continued to talk to Lucas with hopes of procuring the fuel injection system they’ve invested so much in but this, as history teaches us, never happened.


What could've been.

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