CV-style shifter linkage?

[Jeff W]

Talking to a car aficionado I work with and somehow the SL-C shifter cable setup came up, and I'd mentioned issues with heat damaging the cables. He said something to the effect of using a solid push-pull rod style linkage, except the one he was mentioned used CV-style (or similar) joints for the rotation and allowed for non-straight line installation. Assembling a linkage should be possible in a few pieces for the SL-C. He suggested a couple sites like Pegasus racing gear that would have it, but for the life of me I can't find a linkage like this of any type or name no matter where I look. I've seen this stuff when working on aircraft, but this is generally highly specialized and engineered specifically for the application. Do these even exist in any form that could be DIY'd? Pretty sure it doesn't exist, at least not in the functional way this guy said.

 

[Alex]

Why would you want to go through the headache of getting a solid linkage working in these cars ... that would not be fun in the least .... cables work perfectly fine as long as you don't do something stupid like having them sit on your headers. On my 917 they run pretty close to my headers because of the size of the primaries; I put them inside of 2 heat reflective jackets and 10yrs later they're perfectly fine.

 

[Jeff W]

Why would you want to go through the headache of getting a solid linkage working in these cars ... that would not be fun in the least .... cables work perfectly fine as long as you don't do something stupid like having them sit on your headers. On my 917 they run pretty close to my headers because of the size of the primaries; I put them inside of 2 heat reflective jackets and 10yrs later they're perfectly fine.

Something I'm not entirely unfamiliar with, I did aircraft work for a while so push-pull and torque tubes aren't that big of a deal to me, and I was interested in something like that for the car if it was available. I'm not interested in scratch designing a setup with bell cranks and all that, hence the interest in this unique sounding CV-joint style system. Then I could route everything with little concern for heat.

 

[Bill Kearley]

I almost tried to make a rod style shifter. I had a plan that would be a challenge and I would have liked the ( better feel )
The plan was to use steering rod shaft , u joints, standoff supports or rod ends, as sliders. This is on a RBT.

 

[James Carty]

Talking to a car aficionado I work with and somehow the SL-C shifter cable setup came up, and I'd mentioned issues with heat damaging the cables. He said something to the effect of using a solid push-pull rod style linkage, except the one he was mentioned used CV-style (or similar) joints for the rotation and allowed for non-straight line installation. Assembling a linkage should be possible in a few pieces for the SL-C. He suggested a couple sites like Pegasus racing gear that would have it, but for the life of me I can't find a linkage like this of any type or name no matter where I look. I've seen this stuff when working on aircraft, but this is generally highly specialized and engineered specifically for the application. Do these even exist in any form that could be DIY'd? Pretty sure it doesn't exist, at least not in the functional way this guy said.

I have a solid push rod set up. Works great. I have pics and video on my Instagram and YouTube channel.

 

[Brian Kissel]

James, do you have a link to your YouTube channel ?? I would be interested in seeing your setup.

Regards Brian

 

[Jean-Marc]

Bill, James, I am interested too by the concept, that is nice, could you share photos and drawings ?

 

[James Carty]

James, do you have a link to your YouTube channel ?? I would be interested in seeing your setup.

Regards Brian

 

[Brian Kissel]

Thank You James !!

Regards Brian

 

[Neil]

I almost tried to make a rod style shifter. I had a plan that would be a challenge and I would have liked the ( better feel )
The plan was to use steering rod shaft , u joints, standoff supports or rod ends, as sliders. This is on a RBT.

Shifting gears a mid-engine car is an inherent problem no matter how it is done. I ran through a number of iterations of a rod shifter and it is now satisfactory but not it's easy to build. My transaxle is a Porsche G50/01. It has a shifter rod sticking out of the rear case which is rotated and pushed in and out to select gears.
The trick is to accomplish this with minimum play. To this end, it is necessary to use close-fitting bushings and good u-joints. My first design was one that required me to mirror image the gear change pattern and I quickly rejected it. Reversing the shifter shaft rotation solved the basic problem. After a few abortive attempts with plain bronze bearings, I switched to Thompson linear ball bushings for less friction. The mild steel tubing I used for the shift rod became Brinnelled by the balls in the bushing so I switched to case- hardened rod with greater success. The ball bushings were great for linear (back & forth) motion but not so good for shaft rotation. I found that Thompson also offered a flouroplastic bearing in the same cartridge style as the ball bushings so I changed. I found these satisfactory.
Reversing the rotation amounted to creating a linkage that performed this function. The linkage was made from two rod ends joined together. one is a usual spherical rod end to allow a slight bit of misalignment and the other is a ball bearing rod end that can accommodate end thrust. The whole shifter assembly must be well secured with intermediate support where necessary and the u- joints must high quality units.
A right hand drive, right hand shift mid- engine car has an advantage over our USA layout since the shift rod does not need to be routed so close to the engine.

 

[James Carty]

Something I'm not entirely unfamiliar with, I did aircraft work for a while so push-pull and torque tubes aren't that big of a deal to me, and I was interested in something like that for the car if it was available. I'm not interested in scratch designing a setup with bell cranks and all that, hence the interest in this unique sounding CV-joint style system. Then I could route everything with little concern for heat.

If you go the push rod route ensure there is an easy to access single adjustment point. Minor adjustments may need to be made as the transaxle gets broken in.

 

[Bill Kearley]

Nice job Neil, I love that type of challenge and a good end result . Jean , I ended up using CNC ind. parts and cables.

 

[Howard Jones]

Here is what I would use. Design the system so that the U joints are not near the exhaust:

Apex Covered Universal Joint | PegasusAutoRacing.com

Apex and Belden Universal Joints (helicopter joints) are manufactured to Mil Spec MS-20271. Their light weight and tight tolerances make them ideal for racecar shift linkages.

www.pegasusautoracing.com

I designed a rod shift for my GT40 years ago and would have used 3/4 inch OD .065 4130 tubing for the rods.

4130 Alloy Steel Round Seamless | Aircraft Spruce

4130 Alloy Steel Round Seamless 4130 is a chromium-molybdenum general purpose alloy steel tubing that is weldable and is capable of developing good strength. It has been for years the standard of the aircraft industry. Tensile Strength: 90,

www.aircraftspruce.com