Shift coupler for 915?

[moazam]

Does Pelican carry the shifter coupler for 915 transmissions? If so, I can't seem to find it anywhere.

[jmohn]

http://www.pelicanparts.com/catalog/shopcart/911M/por_911M_pedals_main.htm

Good luck,

Jery M
'78 SC

[moazam]

Bingo! Thanks jmohn.

Part number C-424-024-04.



Now then...is it better to go to with the stock shifter coupler or maybe 'upgrade' to a Wevo coupler? Price is a bit more than double on the Wevo. :/

[SLR]

Yep they do, and the bushes as well I'v just ordered them for mine

[dtfastbear]

I just put the Wevo coupler on my 915 yesterday and MAN, what a difference! I didn't try it back to back with a new Porsche part, but I can say that I'm extremely impressed by the Wevo part. Installation was easy and my shifting is much improved after changing to the Wevo coupler and new bushings up front in the shifter mechanism.

Good luck,

Dean

[Shaun @ Tru6]

I put a new factory coupler from our host in mine after breaking original trying to get the bushings out. Hint: don't try to press the rod out, I think dremeling would probably be best.

Note that the factory coupler has the same slop in the bushings that your "worn" coupler does. Aftermarket bushings remove this play. My garage is emphatic that "if you want to shorten the life of your tranny, go ahead and stiffen the joint with (insert other coupler here)." That said, with 220K on the car, I wouldn't mind better shifting for a trans rebuild down the road.

I think Bill Verburg made/found some beautiful brass bushings that I'd love to pick up.

How does a Wevo compare with a Stomski with a Fabcar, etc.?

Shaun

[APKhaos]

Stomski rocks. Installed it a last year, and it has dramatically changed the shift - tighter, more accurate, less slop. Nice on the road, and really nice on the track.

[JSDSKI]

Interesting, Shaun, I've not heard or read that about aftermarket couplers - that a stiffer or more precise coupler will shorten trans life. I wonder what causes the additional wear?

I hope some other tech's / trans guru's comment on this because I'm just about ready to refresh my 72T with a WEVO coupler, new bushings and a Seine System shifter. I wonder if I should stick with the OEM coupler?

[TimT]

I trot out the pic of the coupler I made for about $40 everytime this subject comes up. 5/8's steering coupler. Cut the splined part from a spare coupler I had,fire up the welder. Viola

[emcon5]

Originally posted by Shaun 84 Targa
I put a new factory coupler from our host in mine after breaking original trying to get the bushings out. Hint: don't try to press the rod out, I think dremeling would probably be best.

I didn't have any problem pressing mine out.

Just curious, why do you need to replace your coupler?

Tom

[Shaun @ Tru6]

Scott,

They claim it has to do with shaft vibration while in a forced, less than optimal position. Best I can describe is that if all pivot/connection points were in perfect unison, you could have a fixed coupling from shifter shaft to shift rod, but the fact is they are always a little off in alignment, and that the factory slop in the standard coupler allows for vibration to be disapated and not transmitted to the trans while in a "forced-position" state. I hope that makes sense.

I have to trust them as I've driven another customer's 86 Targa with a 915 rebuild that shifts just like a G50.

[Bill Verburg]

I had the zero clearance bushing and brass pieces made


Installed in stock coupler


The coupler feels the same as the more expensive Stomski unit that was used for a short while. Feel is great. I was ready to buy a Wevo but no longer feel the need.

PM me and I can put you in touch w/ the machinist. They weren't exactly cheap, but were cheaper than a Stomski and feel exactly the same.

There was a reason for the designed in slop, but only time will tell if there are any negative effects on durability, my personal opinion is that there are so many other things stressing the trans that the shift linkage clearance or lack thereof is pretty unimportant.. So far myself and a few local racers are the only ones using this particular set up.

[Shaun @ Tru6]

Tom,

I've been "restoring" the 84 for 2 years now and without a doubt, shifting is the weakest part of this car. I grew up on 240Zs with wonderful open gates that you could ham-fist all day long. Now that I am fairly gentle with a lever, I want more than anything for a smooth transition into 2nd. It doesn't grind, just very stiff. I've tried everything from varying wrist/pressure to adjusting and adjusting and adjusting.


No doubt I need a rebuild, but I am still in the denial phase.


Here's something odd. I never worry about 5th into 2nd when downshifting into 4th, which I do often, that concept is completely foreign in my experience with this car.

[wevoid]

Regardless of opinion surrounding whether aftermarket couplers cause transmission wear, there is one fact that is not covered here - so far.

The stock coupler has only one true plane of rotational freedom - perpendicular to the axis of the pin - it is rotational freedom that allows for misalignment.
The slots in the factory bushes allow a certain degree of rotational freedom (again for misalignment) in another plane at 90°, giving a crude but adequate universal joint. The slots are essential to allow the misalignment freedom on the second plane - the lost motion fore and aft is a legacy of the slotted bush design.

Stock couplers with round hole bushes eliminate the second plane of freedom and for certain could lead to accelerated wear in a number of places in the shift mechanism and transmission. A stock coupler with round hole bushes requires that the shifter be arranged exactly on the same axis as the main shift rod of the transmission if the system is to exist without a "forced position".

As mentioned by Shaun, the factory arrangement allows for all parts to be slightly misaligned - a condition almost certain to exist in all cars.
A true unviversal joint will accommodate this misalignment in a more pure way than the stock coupler.

As for the vibration, I suspect most of it originates in the transmission and Porsche were attempting to isolate the vibrations from the shifter (and driver), not the reverse.

Regards

Hayden

[Bob's Flat-Six]

So a true universal joint would work best with what bushings, Factory?

[wevoid]

A true universal joint would be a complete unit that replaced the factory coupling and therefore the bushes too.
The coupler's made by Fabcar, Stromski, TimT's unit and our own Wevo coupler are all true universal joints.
An interesting derivitive of Bill's unit would be to add just enough slot to the holes to allow a minimum of freedom on the second plane and keep a minimum of lost motion fore / aft, then the low wear, high precision advantages of the brass would still be faithful to the factory intent to allow some misalignment.
Bill clearly states his choice to accept any (if any) detrimental effects of his solution.
Those who go to a true universal joint are choosing precision over possible noise and vibration.
If acceptance of any potential pitfalls, either potential noise, vibration or assumed tranmsission damage are a concern, then new factory bushes are still going offer the best of what the factory decided was adequate to satisfy their own design brief.
This thread proves not only do the factory parts wear out, not all drivers feel the factory solution was totally satisfactory.

Regards

Hayden

[Randy Webb]

Those brass bushings are a perfect item for a small production run for someone to offer -- maybe with some Delrin inserts....

Now, has anyone compared the Wevo, Fabcar, Stomski units to each other? Ha anyone compared them to a factory unit with new, not old and worn, bushings?

This exactly the sort of thing that a car magazine -- like Excellence (listening Pete Stout?) should do.

[Vipergrün]

Hayden, so, is the danger of using aftermarket bushings with the bushings themselves, or that they will require more precise alignment? My shifting has never been better and it's hard to imagine that the smooth shifting will accellerate wear. I'd be more concerned about a missed shift, or jamming into gears with a sloppy shifter. I certainly do not want to blow up my tranny, just trying to understand. Are the folks using the true U-joints better off than those of us using aftermarket bushings?

TIA

-B

[Chuck Moreland]

Having a bit of experience making bronze bushing products, I too thought of manufacturing a product like Bills picture as an economical alternative to the U joint couplers. But after some analysis concluded that it is not the same, just as Hayden points out.

The aftermarket bushes that are not slotted are made of polyurethane and have some give in all planes, providing a true U joint albeit with resistance due to compression of the poly. A solid metal bush has no give and hence is just pivot, not a U joint.

[Shaun @ Tru6]

Originally posted by Randy Webb


Now, has anyone compared the Wevo, Fabcar, Stomski units to each other? Ha anyone compared them to a factory unit with new, not old and worn, bushings?

This exactly the sort of thing that a car magazine -- like Excellence (listening Pete Stout?) should do.

Amen! They seem to shy away from product testing, but any good magazine owes that edit to its readers. I'd much rather see this story than aero mirrors on an old 944. I'd also like to see SteveW's chip go up against X, Y, Z.