The left photo is of an Al Ford 9¨ carrier. Strong and well developed. Lots of ratios available. The problem with these is the gear cut takes more HP to turn them. That is the difference compared to the
Ford8.8 diffs.

      The sprint car racing diff is a nice piece, but expensive due to limited market. It also has the quick change ability built in which you do not need and it adds weight.

      Available from FRPP is the diff housing from the Ford IRS system.
      They do not recommend more gear than 3.27 but that is for cars.
Guys running 3.73 or 4.10 will have a tendency to let her rip now and then which puts a high shock load on things. In the helicopter it is a high but continuous load. It is fairly inexpensive and a 4.3 ratio should be able to be installed. It should also be fairly simple to devise a cap for the lower end when turned on its side so oil can not leak out past a flooded seal. Then with a primary 3.17 planetary reduction made from the Ford planetary parts. will get you 13.6 reduction which is close to your original 14:1. An over run or one way sprag clutch will look after engine out if required to auto rotate. Cost on this should be fairly reasonable compared to other options.

      Just looked at the FRPP website and do not see the IRS housing any more. Should be able to get from the parts dept as they were used in the Mustang Cobra and Lincoln. Recyclers have complete IRS for about $1500.
You may be able to part out just the diff assy. Found the FRPP housing on the Summit web page

      Heidts also makes an IRS Al housing to use the 9¨ diff parts. Al pumpkins available also.

      Then there is the Jaguar IRS which are readily available.

      Dale Davies


      Paul and friends,

      How do we know the rated rpm and torque for the Ford planetary system?
      Do we know the material used for making them?  It would be rather hard to decide on which gear fits which application without such data.

      Gordon Gao

      No I do not. All I know is it it used in the Ford power stroke diesel truck.

      650 ft pounds of torque.

      Paul Lamar




      Hello all,

      Many thanks for all your suggestions and help I am sure it will all be of value to me shortly

      The actual torque of my helicopter is being calculated this weekend and the greatest torque will be

      At full cyclic (so I have been informed), all will be taken into consideration, however if the sprint car box has been used in the

      Jet Exec Kit then it is possible to find something already manufactured for my Scorpion Mazda 200hp Turbo.

      The only thing I would look for would be a pinion which is central to the shaft(axel/spool)

      If anyone knows of something I would be very grateful.


      Many Thanks

      George  Crooks from Aus

      IMHO the sprint car stuff is OK for a piston engine as generally
      they are much lower RPM. In the range of 2700 to 5000.

      For a rotary powered helicopter it is hard to beat a 20:1 worm gear as we are talking 7500 to 8000 rotary RPM to get a decent power to weight ratio.

      Most turbine engines come with built in planetary reductions
      so the out put is n the prop RPM range. In that case a sprint car rear end
      would be useful.

      If you want a rotary powered helicopter that out performs
      the common piston engine helicopter take advantage of the high power to
      weight ratio, high RPM of the Mazda rotary engine. It will
      beat the turbine helicopter hands down on lower fuel burn.


      Paul Lamar

      Gordon,  The E40D  4 pinion planetary s are made from hobbed
(machined) gears and also from powder metallurgy (sintered).  All the 6 pinion
      planetary s which you would be using  are machined as far as I am aware.


   George Grimes


I do not know they are made from sintered gear, really an unbelievable deal.  We can just order a whole set from Slauson? Or do we have to buy from a Ford dealer?  I know Paul sold one a while ago, but that was a one off deal.  I did not follow the whole thing from the beginning, but are there prop shafts offered to the group? I might need one that is driven by the carrier.

Best regards,

Gordon from China

I can order them from Slauson. I am in Germany right now so when I get back on Monday I will order 2. One set for Neal and one for you. What part of China are you in. Henry is in shenzing.

Paul Lamar


Thanks a lot Paul, I live in Beijing.  I just called a friend who is an auto mechanic, and he said the stuff is also available locally. He wishes to order a set for me from Ford. However, the Ford guys asked him the Ford part numbers, not the Slauson numbers. Do you know the part numbers?  I was told that they need the number of teeth, whether it would be 50, or 51 teeth, etc, not sure if the information is correct.


Best regards,

Gordon


The cost is $200 US but the part number in the slauson catalog is not the same as the Ford part number.

I will have to look into what it cost to ship to Beijing. Maybe DHL but PP might be cheaper.
Everything goes by air so there is not a lot of difference in time.

Paul Lamar

Thanks a lot Paul. That is very kind of you. Could you please order a whole kit include the ring gear, sun gear, shaft, o-ring, gaskets, bearings, etc? How do we take power from the ring gear 74?  I would like to have that part as well.  It does not look like 78 as 78 would mesh with the carrier 40.

Best regards,

Gordon

The set includes the ring gear, the planet carrier, the planets and the sun gear.

You must make the shaft and the rest of it. Do you have a machine shop in Beijing?

Chis Hoskins in Tauranga  NZ is making a shaft and the rest of it as we speak.

Neal in Parkes AUS will have to make a shaft and the rest of it.

You fellows should all get together.

I have a full plate getting this rotary ignition in production.
Other wise I would do it.

Paul Lamar


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