Anyone know the specs of the Kirban shifter centering springs? I just installed one and they are too stiff for my liking. I'm planing to buy some off Mcmaster Carr for a lower rate and or shorter spring so there is not so much preload.

They are simple compression double ground flat end springs. Not sure if anyone knew what came in the shifter so I know what rate/free length to look for.

Thanks!

 

No one huh? I figured some of the handy people on here would have done something like this already.

I may try to disassemble tonight and check some things.

 

Well, you can call Kirban directly as I just did and here is what I found out.

They know NOTHING! (215) 766-1611 The lady that I spoke to didn't know and also stated that they no longer sell that shifter. There are no replacement parts or springs.

BUMMER! I really like my Kirban shifter. Guess you are just going to have to disassemble yours , take some spring compression readings and dig through the catalogs to find something similar with less spring pressure. Heck, buy them in bulk and become a forum vendor. :-)

I really like my Kirban shifter. I also like the spring return the way it is.

 

LOL That was my next step to call them but I had no hopes they would know anything. I don't see the shifter on their site anymore.

SO, we will do it the long way as you mentioned. Another option is to compress the springs and give them a little heat while compressed to sag them out (shorten the overall free length).

With the **** I put on, I ended up adding an additional hole to space the shifter handle down. So the original top thru hole on the handle is now used on the BOTTOM threaded hole of the shifter. I think this was ~25mm handle height reduction, but the **** somewhat makes up for this. So I might be back to square one...I was only shooting for a height that I liked given the parts I had on hand.

When everything came out in the wash, the centering is a tad TOO stiff. The throw and feel is good, but I'll reduce the centering force by 25-50% I think ideally. I thought about running NO springs since the stock shifter has no springs and rely on the trans internal spring. That was quickly shut down since the centering springs is what keeps the shifter handle pressing down into the lower box LOL. The shortest the springs can be is theoretically the height of the cavity they sit in with the top shifter lid bolted on. I already had it apart (and forgot to measure the springs) but at free length they stuck out of the shifter body roughly 15mm...which is already 15mm worth of preload.

I'll dimension the current springs and ballpark a rate value. But how nice would it be to have adjustable centering springs Springs like this on McMaster are CHEAP. I'll report back whatever I find for anyone else with this shifter and would like to tinker.

 

EXCELLENT reply! Keep us informed and take a few pics of the shifter and springs so people can see the difference in heights.

Thanks

Bill

 

Well....it's never failure when you learn something right??

Come to find out, the "centering springs" I don't feel are really centering the shifter. Here is why...

The total cavity in which the springs sit is 0.650"
The spring free length + a centering washer that rides on the shifter cross pin and the bottom of the spring = 0.896"
The spring "preload" -> 0.896 - .650 = .246"

I had some spare springs which I ended up cutting/modifying to be roughly the total cavity height of .650"...I think I was around .750" realistically. I placed these springs in the shifter to act as a "zero preload" setup (not to mention the spare springs I had were a lower rate to begin with). Verdict: no change. The shifter felt just as hard to pull over from neutral state. It didn't feel as "solid" either....hmm

Armed with this disappointing info I said screw it, and took the springs out all together and tried it this way. Verdict: no change! However I COULD pull UP on the shifter handle LOL...yahtzee.

Conclusion: It's my belief that the "centering spring" feel has everything to do with the higher pivot point inherent to all aftermarket shifters and the centering spring inside the transmission. These springs simply keep the handle "solid" and always pressing down in the lower box. They are relatively stiff springs which make it feel like once the top plate is bolted down that it's "rigid". However you COULD yank up on your shifter and feel movement if you were so inclined to, you are only fighting the spring rate.

I have dimensioned the stock C6 shifter that came in my car and the pivot point is on the same plane as the lower box/shifter mating surface. Aftermarket shifters move this pivot point upwards which inherently increased the force required to move the lower box linkage the same distance. All in the name of leverage. This is why MGW offers a 25% shifter and a 35% shifter. They play with the pivot point height. You could theoretically make your **** much higher to reduce this effort but then the throw gets longer.

I digress...the original point of this was to spec out the Kirban springs....
Free Length 0.851"
OD 0.482"
ID 0.358"
Wire diameter 0.061"
Solid height (coil bind) .425"

That's my contribution for now...

Here is a link to a place that somewhat documented a rebuild with pictures:
http://www.teamzr1.com/ubbthreads/ubbthreads.php?ubb=showgallery&Number=38 51

CF thread showing a pic of different shaft pivot point heights.
https://www.corvetteforum.com/forums...w-setting.html

 

Next up is playing with the "Anti Venom mod" and see how it feels.

 

AntiVenom mod done with a .063" thick copper washer. No change to "centering force" but it goes into each gate a little easier.

So, looks like "it is what it is".