New shifter?

[Bill Musarra]

I had included this in my build thread but don't know how many may have seen it. While at the Corvette race shop picking up my seats, I was rumaging around the parts bin and came across what I thought was a C5 shifter, but later on found out it was a Z06 instead. This shifter would work well on any of the single rod trans shifters that are out there. I think it would work on the porsche g50s as well. It has a central locking pin that lets you know you are in the straight up and neutral position when installing or working on the shafts etc. It has the fore and aft as well as the rotational movements desired in the rod change setups. I will be experimenting with the 930 to see its adapability. Will post what I find out. Any thoughts on it??

Bill

 

[Ron McCall]

Very nice sifter!

 

[andys]

Less expensive I suspect than a Porsche unit. Thanks for sharing.

For you cable shifter folks, check out the attached link for industrial applications. I have never seen any of these, but perhaps they might inspire some new ideas. Interesting how they translate gate and selector the motions.

http://controls.tuthill.com/Support...ndustrial/MTS_manual_transmission_shifter.pdf

Andy

 

[Charlie M]

Nice shifter Bill. Are there any more in that parts bin? I'd like to get one myself.

Charlie

 

[Lynn Larsen]

Bill,

I like it!

The big issue in my mind is going to be with fore/aft motion if the rod cannot be a straight shot back. If the carrier bearings have a long enough and close tolerance enough sleeve this may prevent any binding that may arrise from trying to push and pull the rod through it with an offset force. The bell cranks doing this will have to be fabricated so that they don't flex (or break), as well. Bell cranks could also be used to transmit the fore/aft forces through the centerlines of the rods and they could also be used to adjust the throw + or -, it just gets a bit more complicated. I am sure that this has been encountered before and dealt with; I am just not aware of how it was done. (A look at aircraft controls that use push/pull/torque tubes may be helpful.)

Lynn

 

[Ian Clark]

Hi Bill,

We've been toiling away on the shifter issue for quite a while. Most shifters like the Corvette unit mentioned and also most kit shifters will reverse the shift pattern since the actuating rod is past the pivot point. So if 1st gear was top left and 2nd strait back (bottom left) these shifters create a 1st at bottom left and 2nd 2nd top left. Not a big deal, just not right.

There's also the question of adequate throw for different transaxles both in stroke and linear travel. Then you need to consider adjustability to fine tune the shifter position. Also accomodating different paths for the acutating rods has to accomplished without introducing friction or binding.

It's a tricky part to design, the part shown here is generation four of our upgraded CAV GT shifter for ZF application. This shifter will throw ANY rod shift gearbox, transaxle or transmission (front engine).

A universal version of this shifter will be available shortly. It will mount in the console or the sill in virtually any GT40 replica. It works the same way as the CAV part however it incorporates mounting points for base plate or side plate mounting. Pictures coming soon. Just the ticket for Porsche, Renault, ZF etc.

The CAV part bolts right into CAVs set up for ZFs. It includes an offset shift arm, u-joints, bulkhead filler panel and shift rods so you can get past just about any engine front accesory drive situation.

The pictures show test fitting in a customer car. The blue aeroquip line makes a great mock up u-joint or flex point for a bend in the rod. The u-joints can be fitted with dust boots too for exposed installations.

The beauty of this part is in being extremely precise yet has virtually no drag. The hardened steel shift rod travels in PTFE bushings and the stick is actuating through an Aurora rod end. Smooth, slick and tough.

Stay tuned for pics on the universal version, help is on the way!

 

[Bill Musarra]

In all my work on the Corvette unit, I had to deal with the problem of the rod actuator. It deals with its translation below the fulcrum point which reverses the travel needed. I was working with bell cranks, but they were too large or too flexible and would not stand up to any heavy loads(read fast shifts). Then there was the translation of the neutral gate. Having to translate that motion along with the fore and aft. I am curious how you handle that motion on the Porsche units. If you could furnish a pic of the trans end of the shifter, it would be a great help. I have considered a straight cut gear on the tailshaft and one on the shiftrod. If they went in opposite directions, then they would have to slide along their gear face. If same direction then they would be fixed. I also thought of a small adjustable rod on the axis of the two rods that would translate the rotational force. Could be on same or oppoaite axis for staight or reversd action. Lots of tinkering. Look forward to your pics on the other end.

Bill

 

[Ian Clark]

Hi Bill,

In the case of shift input shafts existing out the back of the transaxle (Porsche, VW, Audi, Renault) you can buy tailstock mounted shift mechanisms from the sand buggy guys. That takes care of converting the motion at the back of the transaxle. If you send the signal in correct it will end up correct when you shift it.

There's plenty of shift mechanisms available that operate like the Vette unit however the pattern is always reversed. That's why we went to all the bother. The original GT40 shift lever turns directly in the shaft and travels linear with the shaft, so does ours.

I hope to post pics of the Universal GT40 Unit in the next few days. Your problems should be solved

Cheers

 

[Bill Musarra]

I finally have a working model for the Corvette shifter. It took many drawings in my spare time.What was hard was to figure out how to get the fore and aft motion to sync with the rotational action. If the two rods moved in the same direction, it would be easy. The Corvette unit moves in the oposite direction. I thought the rotational point had to move with the linkage rod as it moved fore and aft. That meant the rotational controller moved almost 2 inches in the wrong direction each time a gear was changed. What got me going was the realization that the rotational movement only hapens in the neutral position. Sounds elementary, but believe me it isn't. One of the early models had the tendancy to move the shift linkage in an arc as it rotated along its axis. That would never do. Then I realized the shift rod in the trans goes only through and H type patern, ans It made me think that the linkage pieces had to be at 90 degree right angles at all intersections.
So to test out the theory, I built a working model. Rather the working model made me realize the above.
The revised model works perfectly and has no movement of the linkage as it goes through its motions. You may be able to pick out the movement in the pics(or lack of extra movement). The ratios of movement can bealtered by the placement of the mechanism for the fore and aft. The rotational movement(neutral gate) can be altered by shortening or lenghtening one of the arms of its rotation movement. Now the only thing to overcome is getting the linkage back to the trans and parrallel to the shift rod whithout it binding.

Bill