Rolls Royce Retrospective Part 1: Introduction, Intrigue, and Quirks in Abundant Supply


This is the spaghetti assembly that controls brake pressure. What may not be obvious is the fact that all pedal resistance felt when braking comes from the little rubber nub in the upper right of the assembly. A few mm of actuation results in the valves supplying all the pressure you need. If you were wondering, the left side of this assembly points toward the rear wheels.


One of the reasons for the large amount of lines is that there are two brake calipers per front brake disc, I suspect this was done to get the pad area the engineers wanted without going to a bigger wheel than 15 inches. As it turns out, these calipers are a Girling design that was used on old Saabs, S30 Z cars and much more which saved me a huge headache. I’ll get to that in a later installment.


One last interesting engineering aspect of the braking system is that it incorporates a primitive ABS system! A small cylinder near the master brake control valves contains a steel ball. Under braking force this ball moves to block a port and reduces brake pressure to one set of rear pistons in the four-piston rear calipers. I’m not sure how effective this really was, but I’m impressed by the idea, especially considering it’s fully mechanical. You can see this unit in the previous picture of the brake lines and control valves, the ball has to travel upward against gravity to block the outlet port.


The ride leveling aspect of the system uses small valves tied to the rear suspension to increase or decrease pressure in two rams bolted to the rear shock towers. This was one of the first things I binned from the car, I didn’t want the the complexity or the high-mounted weight. I eventually used these to mount the coilovers, I’ll explain when the time comes.

Before we get to a serious discussion about what occurs at the rear of the car, let’s explore a little more of the engine and transmission. The engine is mounted in three places, and the TH400 transmission has… no mounts at all? The Rolls engineers decided to hang the transmission from the back of the engine, I suspect this is to reduce NVH that would otherwise come from the trans mounts. The chassis also has an air gap in the trans tunnel, maybe this was to reduce heat transferred by the transmission. The addition of massive cats under the floorboards ensured lots of heat however and my shoe once slightly melted to the carpet.

After lots of research I discovered that the bellhousing of the transmission is the later style BOP (Buick, Olds Pontiac). Rolls initially used their own four-speed trans, but it sucked, so they made a smart decision by going with such a proven unit. They also used a Saginaw PS pump to power their own steering rack. I’ve read that the trans used special billet internals but have no proof, I can confirm it was actuated electrically. This allowed for a super light and easy column-mounted gear shift that you can operate with two fingers.


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