Stainless precision shift coupler and rod, for /6 sideshift Options

[smdubovsky]

I've fabbed a new shift coupler/rod as discussed in the previous thread:
http://www.914world.com/bbs2/index.php?act=...f=2&t=58716

The POs side shift adapter and the new one:


The U-joint vs factory coupler w/ plastic bushings


The boot over the U-joint (full of grease)


The tranny end - turned and polished (the tapered hole is even correct).


Its 100% stainless (303/304). Im out of stainless pickling paste so the welds haven't been cleaned yet. (Dont pick on my weld of the nut to the coupler - it was late and the little bugger flops around while you're welding;)

It can report that is works great and completely solves the bind that I use to get in the 1st/R plane (it never was as bad in 4/5 but I dont know why).

In retrospect, I'd use the next larger U-joint and tap the hole vs welding a nut. Both welding the nut, and pulling the boot over it sucked;) I'd also look into using smaller diam or thinner tubing (its currently 7/8" because thats what my old one was.) I didn't want the prototype to have too much torsional twist (calculated 0.75deg @ 10lbft)

FWIW, It sounded like there was some interest. I could make a small production run. They are customizeable to an extent. I can control phasing (the orientation of the set screws - I pointed the one at the firewall out 45deg to make it easier to reach w/ a wrench) I could adjust the length (I understand the V8 guys need longer ones?) I could even lighten it as much as possible (for the racing types) by boring out the tranny end, using the smaller coupler w/ nut, and smaller/thinner tubing. $200 as long as a lot of extra work isn't involved (like lightening).

SMD

[Brando]

Make them all completely hollow, or "lightened" as you say. (IMG:style_emoticons/default/smile.gif) That's the best idea.

At $200/ea I would be very interested in one, and I'm sure many others around here would be as well. I had bought a set of shifter bushings (NOS) and somehow between moving twice I've lost them. Crap.

No more bad bushings for the life of the car sounds like a steal at $200!!!

[Gary]

I'm interested in the bind you had in R-1. Ever since my -6 conversion, I can't get reliably into 1st when at a standstill - it's just that last inch or so. When rolling, I can do it every time. If your rod will address that, I'm in for one! I always figured it might be a slider issue, but I'm not tranny-smart.

thnx, Gary

[smdubovsky]

Make them all completely hollow, or "lightened" as you say. (IMG:style_emoticons/default/smile.gif) That's the best idea.

Time is $$ (and Im not a cheap whore no matter what my wife says;) If I bore out the tranny end it would be ~2.5oz. Not worth it unless racing and shaving EVERY ounce. Plus, boring/drilling deep holes in stainless is a PITA;)

Going to a smaller/thinner tube is 3-8oz savings. The larger coupler is +4oz, but I could bore most out of one end to probably get back to parity. If the tube is too thin, its more vulnerable to a roadside debris hit. Plus, its trickier to weld.

How much are you willing to spend for a few oz? (IMG:style_emoticons/default/wink.gif)

Im not sure if they will work on a /4. Don't they require a shaft w/ a little dogleg/bend in it? I'll try to crawl under some cars @ the ECC and get more familiar.

Gary, go read the post I linked too at the beginning. My problem (and everyone elses) is that the sideshift mechanism bends the rod side to side (not the direction the factory coupler wants to bend), putting the rod in a bind where it goes though the firewall. This happens in R/1 and 4/5. My R/1 just seemed worse but I don't know why (I guessing its due to a tranny or bushing location being slightly offset - its definately not a straight-shot). Anyway, the U-joint allows for this side-side motion and the up-down (like the factory coupler) in an all metal no-slop "lifetime" (theoretically) replacement. You're problem sorta sounds like a slider problem but Im not a 901 tranny expert.

SMD

[Michael N]

Very interested. I changed over a original 6 tail shifter to side shift and have been having R/1st issues ever since. Similar in 4/5th but not nearly as bad. This would solve the issue?

[Mueller]

Looks good...yes, the /4 rods have a bend in them...at least my sideshifter unit does.....

[racerx9146]

I have made a shift rod very similar to yours using the wevo coupler for a 911. It improved my 6 side shifter conversion a lot! Its still not perfect, 4th is still tough sometimes...might be my tranny. Still need to try to adjust some more. Its easy to live with your issues if you are used to them, then you drive someone elses car and think why is mine wierd?

JOhn

[lincoln]

this for the original type trans with tail shifter? i hear a lot bout switching to side shift and not sure really what thats about. is side shift something we wanna do to tail shift trans or this a whole nother transaxle?

[smdubovsky]

Michael, Thats the EXACT problem I was having which started this whole process. Sent you a PM.

Mueller/John, Thanks.

Lincoln, Yes, this is for a tailshift to sideshift conversion (/6 only unless I figure out how to bend the rod). I understand that w/ a box of parts, a tailshift can be changed over to a sideshift. They are supposed to shift better, but I've never driven anything other than my car so have nothing to compare it to.

SMD

[John]

I like it , but I would suggest one slight change.

I would incorporate the stock boot as it protects the firewall bushing from dirt/grit and helps it to last longer.


just my $0.02

[smdubovsky]

I would incorporate the stock boot as it protects the firewall bushing from dirt/grit and helps it to last longer.

John, I thought about that but the early cars boots are NLA and to my knowledge, there isnt any off the shelf solution to fit an aftermarket boot. My car came w/ a cobbled little bolt on thing that gives a place for a tail shift chassis to attach a side-shift boot, but it would need alot of RTV to seal behind it and at least another screw. Its a pretty crappy design and doesn't fit well. PRS914-6 did a better job by making something to fit his monoball setup:
http://www.914world.com/bbs2/index.php?showtopic=59088

I would need donor shift rods to take the oval flanges from - not cheap or easy (or stainless;) I *COULD* however find an aftermarket round-round convoluted boot that either tapers down to the size of the shaft (like "East Coaster" did in the same thread) or weld a round stainless washer to the rod. I'd need to know what size the firewall side is though.

Thanks!
SMD

[IronHillRestorations]

A straight rod doesn't give optimum shifting, and usually puts stress on the shifter and the couplings. Compare the geometry of a stock side shifter rod to what you've made and you'll see what I mean.

I've been making conversion shift rods for almost 10 years now, using a specific jig I made, and there have been no shifting problems. Why did I start doing this? Because I paid $100 for a straight shift rod that didn't work!

[smdubovsky]

Perry,
I completely agree w/ you if using the factory coupler. I think it was the root cause of my binding w/ the orig rod (and I suspect Michaels too), Thats why I started the first thread on the orientation of the factory coupler,and why I built one w/ a U-joint. Using a U-joint corrects ALL geometry problems except for the angle the rod passes though the single bushing at the tranny. That one (unfortunately) has MORE than enough slop to take up the few degrees of misalignment (I calculated around 4deg). When I welded the machined end to the tube I tilted it sideways a little. I can rotate the whole thing under the car a full 360deg and can watch the tranny bushing take it all up so I don't know if its even worth doing that last little tiny kink. The "teeth" that hold the last bushing in look like they'll take up +-10deg of misalignment no problem. The binding w/ a straight bar is only a problem if the factory single-axis-of-freedom coupler is used.

FWIW, that little bushing @ the tranny is the last source of real angular error I have. Even new, it moves about 0.040" in its hole. W/ the ~4" lever to the tranny, thats 0.6 deg slop. The shift tubes will twist more than that much (I calculated 0.7 deg @ 10lbft for the rear tube - which was my best estimate to the force needed to shift the tranny. The factory front bar is smallest and thus a larger contributor). After doing the calcs, it didn't seem like a large enough source of error to bother with machining a more perfect bushing.

SMD

[John]

Understood about the boot. That's one of the reasons I like later model cars.

The only thing I've noticed about the straight rods (which have worked fine for me for the last 15 years) is that if you take a straight line from the firewall back to the side shift bushing on the transmission and then through the shifter attachment on the transmission, the plastic bushing on the ball will slide in and out of the cup as you move the shifter from gate to gate.

The rear bushing may also wear slightly faster with a straight rod.

[smdubovsky]

Understood about the boot. That's one of the reasons I like later model cars.

Hehehe. Unfortunately, they stopped making the /6 before they updated that stuff;)

The ball cup at the tranny moves in and out alot when changing planes left/right due to the arc it traverses. Adding a little when moving the lever fore/aft is no different as long as the bushing is in no danger of coming out of the cup. If the misalignment is 4deg (I measure rod travel 2" end to end) then the ball cup bushing will move 0.014". A couple of hairs;) Absolutely insignificant compared to the movment its designed to handle when traveling in its arc.

SMD

[proto31]

I would be interested in a shift rod if you begin making some more. I would like it to have some sort of dust gaurd at the fire wall. Did you decide to use the larger coupler on the ones that you will sell?

Nice Work!

Dan