Wtd: Tutorial re: "Splines" (building shift linkage)

[RussMcB]

I'd like to replace the small shift arm (that bolts to the shift shaft exiting the engine/transmission) with something custom.

I have a few questions to help me get started: How can I obtain material that already has internal splines? I'm not even sure how to measure the splines. The OD seems around 11.3MM or .44", but I'm probably measuring it wrong. The number of splines seems to be 28, but it's a challenge to count them accurately (old eyes & tiny splines).

My engine is a 2004 Kawasaki ZX-10R. I have two shift arms that I can modify, but I'd prefer to buy alum or steel tubing with internal splines, and weld what I need onto it.

TIA!

[Brian]

the easiest way and probably the best way is to get another stock shift lever and cut off the bit that has the internal splines and start fabricating on to it. If you don't want to do that, you drill a hole of suitable size and broach the splines into it, which means forcing a tool of appropriate shape through the hole under pressure, and it displaces or cuts the metal, and you end up with an internal spline cut. A well equipped machine shop can do that presuming the have or can obtain a tool that has the right spline. Intermediate steps include cutting the splines one at a time, by putting a cutting tool in the compound of a lathe or in a mill chuck, and manually working it up and down, or in and out as appropriate, and by having the workpiece chucked in a dividing head of some sort that can rotate the hole in precise increments.

Trust me, I did this once, and it's far easier to start with the stock lever, and cut and weld to it.

Brian

[formulasuper]

On my Busa I used the stock splined arm, which can be installed in any orientation, by cutting off the shift rod attachment stud/ball flush with arm face & drilling a 1/4" hole thru the center of that end. I then used a 1/4" AN bolt to attach a 1/4" spherical ball rod end to it. Using a bellcrank crossing over to the right side below the tranny that attaches to my original stock push/pull rod running forward to my shift knob, I have zero slop.

[RussMcB]

On my Busa I used the stock splined arm, which can be installed in any orientation, by cutting off the shift rod attachment stud/ball flush with arm face & drilling a 1/4" hole thru the center of that end. I then used a 1/4" AN bolt to attach a 1/4" spherical ball rod end to it.

That's pretty much exactly what I have now (without the bellcrank part) and it works OK, but two improvements I'd like to make are: Longer throw (for more leverage) and an additional arm on the opposite side for a second cable. I like the the idea of simultaneous push & pull during each up & downshift. I think the Stohr has this set up.

I've looked at my current arms and agree that modifying them is probably the best route. There is enough material to make a sturdy part.

[RobLav]

Russ,

I just built my shift mechanism using the stock Yamaha shift arm (oriented a different way).

Used 5/8" steel tubing from the shift lever at the driver's right hand - back to a cross tube over the fuel cell cover in front of the engine. This cross tube is in two pillow blocks with bearings and levers at each side. The cross tube transfers the motion from the right side to the left. From the left side lever to the engine shift arm has 1/2" diameter steel tube.

No play.

[formulasuper]

Russ,

I just built my shift mechanism using the stock Yamaha shift arm (oriented a different way).

Used 5/8" steel tubing from the shift lever at the driver's right hand - back to a cross tube over the fuel cell cover in front of the engine. This cross tube is in two pillow blocks with bearings and levers at each side. The cross tube transfers the motion from the right side to the left. From the left side lever to the engine shift arm has 1/2" diameter steel tube.

No play.

Hey Rob, did you copy me or did I copy you? I think the key to our success is push/pull rods instead of cables.

[RobLav]

I didn't know you had built yours this way Scott. After playing with the cables for a while, I reached the conclusion it wasn't good enough and devised this setup. Seems I'd be in patent violation since you did yours first!

Brandon is somehow using a crossover tube beneath his knees on his Citation.

I just re-measured everything - all the linkage tubes are 5/8" .050 wall. The cross linkage in the pillow blocks is 3/4" .050 wall (or somewhere thereabouts).

And I'll get some pics up later of the car's progress if my camera battery would ever charge.

[RussMcB]

I like the hard linkage and cross over tube idea, but every time I've looked at my car I have not been able to determine a good route. The cables give freedom for routing (avoid exhaust), and might facilitate a whizzy paddle shifter (in the distant future). I hesitate to say that hard linkage is impossible, but the light bulb hasn't illuminated over my head yet. No forehead slapping.

In my earlier post I mentioned a second arm on the opposite side of the transmission shaft. Actually, I'm thinking of a disc that would allow lots of options for cable routing. When I designed my car (tongue firmly planted in cheek), I did not give myself a lot of room. Everything's tight.

[RobLav]

Russ,

Here's a pic of the assembly on the garage floor. The cross tube in pillow blocks bolts to my fuel cell top and is at the same height as the engine shift lever.

[RussMcB]

Looks, good Rob. FormulaSuper has been trying to convince me to go that route ever since I started complaining about my car's shifting. My car is partially disassembled right now, so I can't easily rethink the hard-line routing, but I wont rule it out.

I decided to go ahead and hack up the shift arm and weld the disc to it. Here's how far I've gotten. Later I'll add holes for attaching the rod end(s).

[cparsons]

Hey Russ, for what it's worth, I did the same thing you have done, and will use push-pull cables. It seems to work fine but have not road tested yet.