As there are a few others out there who may be using the RD1A, I thought I'd pass this along.

I originally bought the RD1A as it was enough for the power that I planned to produce, but then plans changed and I ended up with a turbo so that I can have excellent short field performance. So I should have bought the RD1B instead.
    The biggest difference between the A&B is that the A has a 4-planet gear set in an aluminium cage from a Ford C6 transmission, while the B has a 6-planet gearset in a steel cage from the Ford E4OD transmission. The reason these are not usually a direct replacement is that the 6-planet gearset has 24 small lugs around it to hold it stationary in the housing, while the 4-planet gearset has only 12 larger lugs.
    I got to thinking there must be somebody making a 12 lug, 6 pinion planet gear and after much exhaustive searching I finally found one. Actually I found two sources but as neither had pictures in their listings, I phoned first. The first claimed that it simply didn't exist and if it was in their catalogue it was just a mistake. The second didn't seem to know much about it and didn't have one available to look at, but was certain that it would be as described. So I took a chance and ordered it since it was only $92. I received it last week and it is a perfect fit into the RD1 housing and perfectly matches the existing ring & sun gears. I've checked with Tracy on this and he says it sounds good but also added "There are a couple of other details that are different on the B drive (larger thrust bearing on the ring gear bulkhead) and an updated Sun gear from a later model but those are not critical."
    So if you also have an RD1A and would like to update it, then this is an inexpensive solution.
This can be seen in the attached photos showing the 6-planet set from the E4OD (from RWS site), the old 4-planet set along side a new 6-planet set with the mating piece of the RD1 housing and the new 6-planet set fit into the housing.
The source was Makco Distributing,
part #A36584E  Planet Rear, E40D, 6 Gear  Steel, with 12 Lug Hub     $92.27

or a direct link at http://www.makcotransmissionparts.com/A36584E.html

Weight;  4 gear alum - 1033 grams. 6 gear steel - 1741 grams.


Todd
C-FSTB