Short shift kit

[AJH]

I'm considering a short shift kit. The Rennshift one seems to fit the bill for my 901 4 speed box. My understanding is that the Wevo requires some 915 components and the Porsche kit is for the 915 only. I know they are not a cure all but I still like the idea of a shorter throw. I've found that the bushes are worn on the shift linkage so I have a set of new plastic bushes but 'while I'm in there' it seems like a good time to install the short shifter.

Does anyone have experience with the Rennshifter? And likewise are replacement plastic bushes adequate or should I be installing brass ones (Pelican) or one of the upgrade linkages?

[9er]

I have had the Rennshift, but would buy the Wevo next time. (both priced similarly)
For the rear coupler I would discard the original and use a Wevo precision coupler or Stomski.

[Fishcop]

They cure nothing Andy... Shorter throw means a change in the leverage fulcrum and as a result it loads some internal gearbox components and arguably leads to shortening component life. It 'quickens' the action of the sliders and pushes the synchro/brake bands/energiser rings quite hard against their beds whilst the matching gear is still deccelerating = extra wear.

What both units offer is superior mechanisms and in combination with all new bushes, will make the shift 'feel' better. Nothing fixes internal wear/sloppy-ness/synchro grinding like a rebuild.

The Wevo's mechanical throw is actually identical to factory.

[e72phil]

The Rennshifter works great and is a complete unit which bolts straight in. I understand the Wevo needs the 915 shifter housing and adds in new 'guts'. I have had the Rennshifter in the 72E for years and have had them in other P cars. The positive shifts they ensure are well worth the money, I think.

[ELSPORTO]

I put a Wevo precision coupler in my '68 sporto.

I also replaced all the shifter bushings.

It was a quick and affordable job and it made it feel better.

Maybe mail Wevo and ask about their new short shift for 901 - a couple of months ago I got an email from the technical Director at Windrush / Wevo;

"We are also working on a low profile 901 shifter, one that fits under the carpet and has the same general appearance as the stock 901 shifter – alleviating the need and look of the 915 shifter base"

[AJH]

Thanks for your responses.

John I would have thought the opposite. A short shift with less leverage would be able to apply less force to the internal components. The downside being higher force required at the stick end and less fidelity. Would it not be the same as simply holding the gearshift 1/3 from the top and changing gear?

[9er]

I think the new shifters (and also factory short shift kits for later cars) change the position of the fulcrum increasing the amount of force which can be applied.

[Merv]

I spent some time last week changing the coupler bushing and checking alignment with the shaft to the gearbox. With some fiddling I found a significant improvement in the precision of the selection of all gears and a better use of the first /reverse plane spring action. It is possible to shorten the throw as well but that may carry some risks or consequences as these are older design boxes on the early cars.

[Fishcop]

I can't claim to be a gearbox expert, but I've rebuilt a couple and understand the slider/fork/synchro components. Changing the fulcrum to make the shift fast does the internals no favours as the ZF design requires 'time' for the synchros to spin down. The later Gertrag G50 box resolved these issues and it shifts like butter.

I will be catching up with Hayden/Wevo in San Carlos next fortnight and will probably grab a beta 901 shifter to test in the green car (they aren't due for release yet). As you know I've got a full Wevo arrangement in my 915 boxed 69 and can't imagine how you'd top it.

[reedminor]

our gearboxes are baulk ring synchromesh, and while you can do it the gearboxes really don't like it. They rely upon smooth and (relatively) slow inputs

I had planned to fit a Rennshifter to my 68L but was turned off by the wear on the internals of the gearbox ( plus I only have the car on the track maybe once a year).

The clincher was when I read that Alex Webster didn't run one in his old 67S race car.... a very successful, well prepared and quick little car. A well adjusted standard set up was good for Alex and is just fine by me.

[e72phil]

The Rennshifter has the provision for 2 fulcrum points allowing different degrees of leverage and throw. The housing is about the same size as the factory 915 alloy shifter and the rubber shift boot fits over it the same as for the 915 shifter making it look outwardly the same if you are looking for 'originality'. Since everything is new and has more precision machining and bushing, the feel is vastly improved and gear selection is extremely positive. I find this fact alone improves your gearbox wear and life since you arent crunching gears with a shift lever that feels like a spoon in a bowl of porridge.

the Rennshifter also has different available shafts with length and angle changes available to suit your personal requirements.

I used to have an affiliation with J West engineering but not any more. The guy who makes them is a small business owner and a Porsche enthusiast, like the Wevo guy. He just makes a complete swap over shifter, literally unbolt your old one and bolt in the new one.

[AJH]

Once again thanks for the feedback.

I think what I'll do for now is to install the new bushes and wait until John gets back from Rennsport and have a look at the Wevo. Ultimately I know that the shifter / bushings etc will only address half the issue. In the long run a gearbox rebuild is probably on the cards to replace worn synchros.

[mrar]

What's wrong with standard, when set up properly?
You guys must be looking for that edge at the stop lights or something like that.
Get a bigger more powerful motor if you want to go faster.

[T-DUB]

My shifter experience has been a full circle
Original > Renneshifter > Original

Racing in Sb Historics, the speed of the change on the short shift was eating my syncros alive, resulting in multiple rebuilds.

My final set up now is Original shifter, Wevo rear coupling and all new bushes and slowing down my shifting action especially when shrouded in red mist.....easier said than done.

As a side, I did really like the tight positive feel of the Rennshifter, if you can slow your change action down SIGNIFICANTLY you may not eat as many gearboxes as I did.

[CamBiscuit]

In my old ST I had a stock shifter. Mark Poole had renewed the springs with slightly stiffer ones and with new bushes all round it was great.