Rennshift hard to shift after install?

[Maxhouse97]

I just installed my Rennshift short shifter into my G50 Carrera. It has 30% level travel, so I expected some more shift effort. However, it is significantly more - to the point where I am thinking about taking it out and putting the stock shifter back in. Has anyone else experienced this? As part of the kit I replaced the shifter bushing and two of the associated O-rings. No problems noted during install. Any ideas?

[Por_sha911]

Do you have the linkage lined up properly?
I was thinking about buying one so if you decide to sell it, let me know.

[sc_rufctr]

I'm concerned that a G50 equipped car would be harder to shift after the install of the Renshift.

I have a Rennshift in my 915 equipped car and it shifts "almost" good but it wasn't always like this. When I first bought the car it had a very ordinary shift... It was so bad that after driving my daily (VR6 Golf) the Porsche felt like a very old tractor. I know it's not the same gearbox but the 30% reduction in travel shouldn't make the gearbox shift poorly. More effort while shifting would be a normal side effect.

I'm sure you've checked all of the obvious stuff but re check just to be sure.
Just to confirm, You could re install the old shifter and see if it shifts like it did before.

The nest step for me is a complete gearbox rebuild. My old girl is 31 this year and I figure she needs a freshen up at the very least.

The current situation with my gearbox remind me of another issue for me. For years I have struggled with my weight. I tried absolutely everything to loose weight except for DIET and EXERCISE. And guess what... I didn't loose any weight! Once I made the commitment to loose weight and stop mucking around, the weight dropped off me. I started a good diet and spent an hour a day exercising. (everyday)

So using this analogy I think the next step for me is a rebuild. Sure I could muck around for the next few years with different motor mounts, shifters, linkages etc But at the end of the day if the internals are worn then no amount of external fiddling is going to fix this.

I've even considered designing and building and cable shift system for my car... Again more mucking around. I've also enquired about and internal gate shift system from WEVO... Just to make the problem even more complicated.

So the point of this long reply is that just maybe your gearbox needs some attention from a professional. I know you feel frustrated because the install of the Rennshift was only meant to make things better... And not worse!

[deep_uv]

I have a Rennshifter for my 915, so not an expert on the G50 version. It took a couple of trial and error adjustments at the rear coupler to get it just right. Mine was tight at first, but once I used it a while, it loosened up. I assume you've checked for binding and that you lubed the bushings?

[mb924S]

I installed a Rennshift last summer in my '71 911 with a 901 gearbox. Not apples to apples, I know.

However, there is no mystery to the mechanics of the Rennshift, it's pretty simple, a straightforward mechanical device. In my opinion a good one, well designed and built.

As long as your coupler is is good shape and properly aligned (and the cup and front shaft bushing at the front are fresh - you did replace them I assume), the forces from the shift lever will be transmitted efficiently to the gearbox. If your car isn't shifting well its (i) improper installation of the shifter, somehow (ii) coupler is sloppy or misaligned or (iii) trouble down the line in the transaxle or clutch.

I suspect that you have some problem in your shift linkage/transaxle system that you hoped the Rennshift would remedy, but the problem isn't in the shift lever assembly at all.

[Maxhouse97]

Ok I have a couple of questions:

1. Are you supposed to lube the shift rod bushing (the big plastic one where the shift rod comes from the transmission to the shift lever)? I don't think it was lubed when I went in to swap it out and I assumed that I did not need it.

2. I did have to disconnect the shift rod from the coupling at the back (by the rear seats) in order to install the Rennshift. Is there a way I could have messed this up when I put it back in? Are there specific adjustments to make in this area? I read something about it on here, but I thought it was 915 specific. Could I have installed it upside down (I didn't think so since the hole at the shifter end was angled a certain way, but I am not sure)?

Immediately after I installed it it felt really good, but after a few days it started getting stiff. Based on that a lack of lube somewhere may be the culprit. Where should I lube and what should I use?

I was going to re-install the stock one to see if there is a difference, but if I can get it settled w/o I would prefer to keep it because I like the shorter throw...

[Por_sha911]

Originally Posted by Maxhouse97

Immediately after I installed it it felt really good, but after a few days it started getting stiff.

This is the clue to follow. I'm thinking that a lack of lube would have showed up right away. Did something loosen up and get out of alignment?
Or, you can just give up and send that thing to me for proper disposal.

[efhughes3]

Did you bother to contact Rennshift?

[Maxhouse97]

Rennshift has been less than stellar to deal with. First they sent me the shifter with no new bushing or o-rings. I discovered this after I tore apart my car (my bad). Then I had to wait a week until their package arrived. Next, once I finally got down to installing the o-rings, I discovered that one of the ones they sent me was the wrong size. Since I didn't feel like waiting another week, I re-used the old one (it seemed pretty pliable and my auto parts store didn't have the right size).

So can anyone tell me where exactly to lube and what to lube with? How often do you have to re-lube? Again, the big bushing (with the "tooth cut out of it so you can fit the shift rod in") didn't not have any substantial lube on it when I took it out, so I am not sure if it was just dry or a non-lube part. It is in the pic below (red part).

I was more worried about the part further aft - the coupler (square looking part with the four holes). Is there a way to get that hook up wrong? Is it a fussy part?

[JWest]

Originally Posted by Maxhouse97

Rennshift has been less than stellar to deal with. First they sent me the shifter with no new bushing or o-rings. I discovered this after I tore apart my car (my bad). Then I had to wait a week until their package arrived. Next, once I finally got down to installing the o-rings, I discovered that one of the ones they sent me was the wrong size. Since I didn't feel like waiting another week, I re-used the old one (it seemed pretty pliable and my auto parts store didn't have the right size).

Yes, a mistake was made and the bushings parts were left out of your original package. However, this does not warrant a gross misrepresentation of our response.

You called on Thursday afternoon to let us know, and according to the electronic tracking information the parts were accepted by the shipping company on Friday February 06, 2009, 2:32 pm, and were delivered to your house on Monday February 09, 2009, 2:51 pm. The next business day is hardly equivalent to a week.

The o-rings are the factory parts and I have had no issues installing them. You are comparing it to a 20 year old part so it may not look the same.

No lube is required on the shift rod bushing. It is a graphite impregnated plastic. It is a tight fit, as the factory made an update over the original bushing in an attempt minimize shifter rattling.

You can disconnect the coupler at the back of the shift rod and move the shifter independently to narrow the cause. Then you can loosen and/or disconnect the upper pivot of the shifter (the cross-bolt with M6 nut) to further uncouple the mechanism. This should quickly lead to the problem area if done systematically.

The most likely possibilities are that one of the o-rings is pinched and binding, or either of the shifter pivots are overtightened and bound up. These are assembled with locking nuts and must be adjusted to remove all perceived play but still leave enough clearance for free motion.

[Maxhouse97]

James,

I apologize - it was less than a week. However, I don't have time to work on my car at night after work, so it was a week until I got to put my car back together.

Nevertheless, the second o-ring you sent me is not the correct size (as you can see in the pic below - no amount of age can make up that size difference). I can deal with the inconvenience of one mistake, but after a second (with the prospect of having to wait another week in my time) I hope you can understand why I decided not to call back.




Regardless I am just trying to solve my current problem. I guess I was right in not lubing the shift rod bushing. I have also tried loosening both shifter pivots as much as possible but that did not work. It is the fore-to-aft movement that is difficult. I will have to tear it out again this weekend to see if the shift rod is binding on something (there were what I believe to be fuel lines under there - maybe one of them is rubbing on the rod).

I assume that the shifter coupling is not the culprit since you did not mention that.

As a last resort I will install the old shifter to see if there is a difference between the units. Without the lube, it could only be a number of things. I will check on that o-ring though. Thank you.

[Maxhouse97]

OK so I took my shifter apart today and I think I found the culprit - the shift rod bushing. Once I uncoupled the shift rod from the couple, I found it took significant effort to move the shift rod by hand. When I was doing this, the only thing the shift rod was attached to was the shift rod bushing. So the friction created between the bushing and the rod was the reason for the increased effort. I also noticed rub marks on the metal where it passes through the bushing - it must really be a tight fit.

Is this normal? Was my old shift rod bushing just worn (and thus probably not as tight fitting)? As part of the Rennshift kit, I was given a new bushing. James mentioned that they were updated by the factory (made to be tighter fitting) to eliminate vibration.

I wonder if this will loosen up with age. Should I add some lube even though it is not called for? Is there a way for me to get the old style bushing? I don't really see much point in installing the old shifter now. I like the shorter travel of the Rennshift, I just want to get rid of the increased effort.

[Maxhouse97]

Going to start a new thread about the new shift rod bushing...