Porsche Transaxle Cable Shifter.

Rupunzell

Rupunzell

Bernice Loui
As some might know, the LeMons exxe race car now sports a PP Mazda 12A rotary with a Porsche 914 transaxle (901). One of the serious problems was making the shift linkage work. Initially the cable shifter set up did not work well at all.

it got completely re-desiged and this is the first set-up of the new shifter on the Porsche transaxle case.
[ame="http://www.youtube.com/watch?v=aRM_4eFByWw&feature=plcp"]Lemons X Rear Shifter 051112.mpg - YouTube[/ame]

Since then, the shifter assembly has been completed and installed on the LeMons racer. More on this later.

Bernice
 
Nice machine work...

and a clever, compact design to transfer fore/aft motion to in/out motion.

Was that a "Jet" milling machine?

Pete
 
We ended up using a cable shifter in the front from a MR2.. modified that too. Originally this set up used a cable shifter from a Dodge.. which means the 2/3 position is reversed, so the cam got rotated 180 from this video. The shifter assembly on the Porsche box also has a centering spring that keeps the transaxle shift shaft referenced to 2/3.

This is the prime failing of the Porsche transaxle shifter mechanism. The shifter control shaft floats between R/1, 2/3, 4/5.. which makes finding gears difficult. Adding a spring to keep the shift control shaft at 2/3 makes all the difference.

The drill/mill is a Rong Fu RF-45 made in Taiwan. Got it new, all USA made tooling to support it. The rigidity is OK for what it is.

if I were not space limited, the mill would be more like a Cincinnati vertical/ horizontal, KEARNEY & TRECKER or an Abene VHF-3. I'm not a Bridgeport fan after using them for a very long time. There are better mills on the market for similar or less cost


Bernice





Pete Whitstone said:
and a clever, compact design to transfer fore/aft motion to in/out motion.

Was that a "Jet" milling machine?

Pete
Click to expand...
 
Some people have the nicest toys

Every time I look at a shop video, I kick myself for selling my milling machine.
I had a good one and thought it wouldn't fit into my new residence, but when the dust settled, I was wrong. :wall: :mallet:
 
Bob,

I have a friend who has a shop in SF Morgen's machining. His place has some OLD SCHOOL machines but man are they sweet. I have a back-log of projects for him. The 2 things I wish I had are a heavy drill press and milling machine...That would be nice.
 
Cable Shift Setup

Very impressive design and fabrication. Would you share the bill of material and design specifications with us or do you plan to build and sell these as a kit? Email me at hcarraro*hughes.net or PM me. I have a tail shifter with a cable shift setup that is incomplete. Yours is far superior. Thanks for sharing your design.

Thanks in advance,

Henry
 
No,no and no...

This shifter is too complex to offer as a kit as it requires machine work modifications to some of the Porsche gear box parts. There are a lot of little parts that make up this shifter assembly and each one is made by me and there is little motivation for me to do this again. Making drawings for this would be a significant project for a full time CAD jockey.

The shifter in this video is the initial mock-up, since then it has been installed in the LeMons racer and working. I'll post another video of how it works in the exxe and a image of what is inside.


Bernice


hcarraro said:
Very impressive design and fabrication. Would you share the bill of material and design specifications with us or do you plan to build and sell these as a kit? Email me at hcarraro*hughes.net or PM me. I have a tail shifter with a cable shift setup that is incomplete. Yours is far superior. Thanks for sharing your design.

Thanks in advance,

Henry
Click to expand...
 
Hey Bernice, that's what you get...

...for throwing out such fine looking bait! Ha!
Can't say that I blame him or anyone for coveting your work.
All great stuff. Much appreciate your work and sharing it with the group. :)
 
mmmm..ahhhh. why?

OK, why do this? Seems extreme vs just using a Fiat motor, tranny etc. What are your really going to gain?? I am not gettin it, help me out.
 
The LeMons racer has a Mazda 12A Peripheral Port rotary engine in it sitting north/south in the x1/9 engine compartment. This rotary has a LOT more power than any stock or uprated NA 1500cc Fiat engine.

[ame="http://www.youtube.com/watch?v=jbzrZvtB_lE&feature=relmfu"]Lemons X First Fire 2.mpg - YouTube[/ame]

This is why a Porsche type 901 transaxle was used. Fitting a rotary engine like this to the stock Fiat transaxle would not only be a chore, but that rotary would toast it in no time flat.

While we still have a many things to address in this version of the LeMons x1/9, once it is up and running properly, I'm worry that the Porsche 901 will not survive the amount of power transmitted hour after hour of hard endurance racing.

One lap at Button Willow race way during a LeMons race. The car is not even close to being sorted out yet..
[ame="http://www.youtube.com/watch?v=xY6pyHxf9NU&feature=plcp"]Pel Lemons BW Fast Lap 120411.mpg - YouTube[/ame]


Bernice

Dallarax19 said:
OK, why do this? Seems extreme vs just using a Fiat motor, tranny etc. What are your really going to gain?? I am not gettin it, help me out.
Click to expand...
 
What About an F40 Transaxle?

I see the Fiero guys are having good luck with the F40 transaxles. They are cheap, six speed, and stand up to V8 torque levels.

Has anyone tried one in an X?
 
Rupunzell said:
While we still have a many things to address in this version of the LeMons x1/9, once it is up and running properly, I'm worry that the Porsche 901 will not survive the amount of power transmitted hour after hour of hard endurance racing.
Click to expand...

Bernice and I argue back and forth - while the rotary makes crazy power for small displacement, it's pretty low torque. The 901 is used in many v8 conversions in 914s, and has been raced for decades. They have their known weaknesses (fragile 1st, intermediate plate failure) - each of them have known cures - downside is all of them are frigigng expensive to fix properly.

Rupunzell said:
One lap at Button Willow race way during a LeMons race. The car is not even close to being sorted out yet..
http://www.youtube.com/watch?v=xY6pyHxf9NU&feature=plcp
Click to expand...

:grin: Car is just crazy fast - and wasn't even running in the power-band in that vid. When it's sorted, it's going to scare the crap out of me.

That should be fun.
 
I just cant wait to ship my 850 up there so it can be fitted with that same linkage....:):)

[ame="http://www.youtube.com/watch?v=TUlp5G7nEXs&feature=plcp"]Mystery Race Car - YouTube[/ame]
 
The F40 is really a SAAB designed variant of the original 5 speed SAAB design. This was one of the designs GM got after they purchased SAAB.

5 speed Fieros were delivered with a Getrag gear box. The other problem is gear ratios, what is ideal for a rotary is not ideal for that GM v6.

The problem with a transverse gear box is the drive axle interference with the exhaust ports on the rotary. Overall performance of the rotary is very dependent on the exhaust system and using the rotary with a transverse gear box limits what can be done for the exhaust system.

Here is just one rotary powered exxe with a Getrag 5 speed from a Fiero.

[ame="http://www.youtube.com/watch?v=BX9reVN0Dhs"]Test run in the Fiat X 1/9 - YouTube[/ame]

Bernice

nucleus said:
I see the Fiero guys are having good luck with the F40 transaxles. They are cheap, six speed, and stand up to V8 torque levels.

Has anyone tried one in an X?
Click to expand...
 
re F40 Transaxle in an X1/9

Rupunzell said:
The F40 is really a SAAB designed variant of the original 5 speed SAAB design. This was one of the designs GM got after they purchased SAAB.

5 speed Fieros were delivered with a Getrag gear box. The other problem is gear ratios, what is ideal for a rotary is not ideal for that GM v6.

The problem with a transverse gear box is the drive axle interference with the exhaust ports on the rotary. Overall performance of the rotary is very dependent on the exhaust system and using the rotary with a transverse gear box limits what can be done for the exhaust system.

Here is just one rotary powered exxe with a Getrag 5 speed from a Fiero.

Bernice
Click to expand...

Thanks for your reply. I've built a handful of 13Bs forced induction and NA, so I totally understand why you would go with a longitudinal layout for a wankel rotary, otherwise your exhaust ports are pointing straight into the transaxle.

I think your PP is very cool BTW; I built an RX with one and it was crazy powerful. Surprisingly tractable too once you got to about 1800 RPM. Mine was a 13, so I didn't spin it above 9K, but it was very strong. That car was a total sleeper too, stock 2nd gen GXL RX-7 with all homemade ports, I think I sold it for $2500 because I thought the ports were ugly, but it would smoke the tires in 3rd gear.

I'm thinking an F40 for a high-powered non-rotary X1/9, so I can maintain the rear trunk.

Nucleus



Nucleus
 
Nice milling job Bernice

and that background music sure makes it fun too.
Professional as ever, thanks
 
Gertrag and Exhaust location.

We opted to use a intermediate shaft for the drive shaft, getting rid of most of the interference for the exhaust. 2.5' to 3" bends.

CIMG5837.jpg


Now, we built this car for hillclimbs, not road racing or autocross. The larger distance in gearing works very well. 3rd gear at 7k is 130mph. This was confirmed during dyno pulls.

Regardless, any solution you attempt would be a race application only as you would loose the rear trunk.

Eric.
 
My Lord, Bernice...

There is more time, engineering, technology, and sweat in the mechanism than any other single piece on that car.

OK... maybe the trans itself but there were probably a hundred guys designing that! They just forgot to make a reliable shift mechanism.

Great work and continued success!
 
Nice Video.

Now, let's hope people don't get to "ham fisted" when driving the car...

At the last chump car race I had to replace the flexible linkage between the transmission and shift rod. Someone was trying to shift and was ramming it into gear... I have never seen one bent before.

I can't wait to hear how it works on the track.

Eric.
 
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