We had a discussion on replacing the ball cup way back when on PorscheFans. I was bitching about how that round bearing on my '83 prevented me from moving the front rod far enough over towards the side of the tunnel to have reasonable access to the lock nuts on the ball cup. At that time, Kurt Gibble had an '87 and he said his car didn't have the bearing on the torque tube, so he didn't have the problems I was having. Ed Ruiz had his late production '86 back then and he didn't have any difficulties either.

Jim - did all model years have the bearing on the torque tube? Note that the picture Bill posted from the service manuals was originally generated for the early model year cars. I don't think they ever updated that picture in the revised editions of the manuals, but Kurt's and Ed's experiences made me wonder if the bearing went away in later years.

 

PET6 does not show a model year range for that bearing bracket.

 

The very early car 78 that bearing was bolted to the BODY ...bad idea so it was moved to the tube where it remained forever. It is covered by the foam and easy to overlook but without that anchor point the shifter would not work anything like it was designed to .

 

The guys at CT automotive took a look at this and took a stab at a repair that might work.

They had a threaded bolt and a colar that were welded together. Then , the colar was welded into the broken hollow shaft. this metal was real thin too.
anyway, we drilled the broken shifter bracket piece and put a nut on it. (to be assembed when the shaft is pushed through the bearing from the front .

Just to be sure, we drilled an 1/8" hole through the tube collar and bolt. If a weld breaks, then maybe the roll pin could keep things together to finish a race.

seems pretty strong, especially compared to the little spot weld that gave way on the ball cup itself, where the threaded part joins the ball cup. (ive welded that too, as it did break and did that at the track where it has been solid ever since.)

The middle picture shows how the piece is oriented. when its tightened down, its a pefect, puzzle piece fit.

sure makes the shifter lever assembly easy, having that part able to be bolted on after the shifter is assembled.

mk

 

I like it.

 

MK
I like the hole you cut in the body to access the rear shifter linkage....saved a little weight and makes it WAY easier to access!

 

Thanks! I just snapped the ball cup using two steel hose clamps in series, wrapped around the torque tube from that access hole. just used the mikita with a 8mm socket and it slowly just pressed it through. I forgot, that once it is on, it is kind of loose on there. good news for the new stud and bolt shifter linkage, even though they have a pretty good notched fit. (there is no side to side resistance in the ball cup as it allows for 2-3rd shifts going to 4-5th shifts, etc)

I think i know how the shaft could have broken. If it wasnt perfectly aligned at the ball cup (orientation)
then, with a move to the right or left, you could hit a stop of the ball cup and be twisting on the shift mechanism weld. since the metal is pretty thin, i can certainly see how that could make it weak and fail. Dont know if that is what happened, but Its something i didnt notice when i changed out the ball cup in the first couple of failures. Orientation to spring loaded neutral on the shift lever is important.

mk

 

Hey Mark now that your done experimenting, I would suggest that you call Carl and get one of his front shift rod couplers and get yourself a new front shft rod, have some extra metal welded on around the shifter bracket , and the shifter pins also touched up with the welder. Since you have a hole in the floor installing these parts should take not more than an hour.Then you can forget agout it!
Your repair though holding will soon fail and the front shift cup is not far behind. Some of this is proofed by you already drilling a hole for a roll pin, that out to work for for about 2 spirited laps

 

have you seen the tubing this shaft is made from? have you seen the factory weld (or spot weld) that connects the ball cup to the shaft? Its a square cut out of the ball cup about 1/8" square. no wonder it broke off. I welded the entire shaft to the ball cup in 4 places. its ugly, but it aint going anywhere.

The shaft where it broke at the shifter mechanism, is very thin material. what i did with a colar and the bolt, was weld it to several parts of the tube and it isnt going anywhere either. the nut on the end is locktite'd on and torqued down. if you look at the mechanism, it is clear to see if the ball cup was not oriented correctly, i could have been maxing it out left to right, and stressing the part right underneath the shifter. Hence, the break. now that it is welded and bolted, the slight force that is applied to engage the gears, and the oz-in of force needed to find the gear tracks (ie 1-R or 2-3rd or 4th to 5th) is minimal.

the only force on this mechanism is going into 3rd 4th or 5th, and it still is pretty slight. heck, ive seen welds like this on suspension components, or things that take real loads! This is a perminant fix. Oh, and the roll pin is just a small strength adding component. its through the collar, bolt and ends of the shaft. more to just strengthen the bolt and collar weld, just in case.

Ill give you a side bet of $50 it lasts the season .

The only thing i would want to do would be to replace the ball cup insert now. it is a little loose but not from the perspective of coming off, but when it is on, it has some play. however, there is a lot of play in the gear box mechanism itself, and its not a big deal for me.

Its fixed, it works and im pretty confident it is strong enough to last several 1000 shifts!

Now, do you have any idea what it takes to replace this front shaft, even if i was going to attempt it? as it was, i could barely get the shaft up on top of the torque tube to guide it through the shaft bearing. i had to use string to pull it through for its initial line up, then, with the ball cup removed , i had to push it through the hole with a vice grip for leverage. (that hatch hole was barely big enough to do this.)
If i was to replace the entire shaft, there is no way that that is an hour job. the entire exhaust has to drop, with the heat shield and even then, i dont think that the bearing and its 2 10mm nuts would be that easy to access, not to mention putting it back in with the shaft on the bearing. coming from the rear would probably be an easier go of it.
That little hatch opening is pretty usless , except for working on the ball cup where it is very handy!


Mk

 

Mark.
Do this remove the exhaust, remove the heatshields , pop off the ball cup with a small 10mm wrench undo the securing nuts for the forward shaft holder above the TTube. You should be able to slide the piece forward and out. With your new parts(used) I would weld an additional piece of metal to the junction of the shifter connection and also weld some extra to the shifter pin. Refit the new rod with the support on it then screw in you new shift rod coupler and use loctite on the securing nuttest all of the connections then go racing.
From looking at the failures you have had i would say you have been overstressing the parts in the heat of racing, thus your failures, it would suck to lose a race because the fatiged shaft/ball coupler failed

 

Probably good advice.

I have the new shaft coming from 928intl and will test this fix for awhile. I think the ball cup reinforcement is better than a new one, as this was a new one, before it broke. the alternative is Carl's part. however i dont like the fact that the side to side motion is not cushioned with a plastic bearing. You saw my pedal shaft, right? metal on metal is not good on a moving part.

I noticed that the lower pin on the rear shaft is loose too.

I do think the fix on the old shaft is probably as strong as a new one.

I did take the easy way out, and hopefully, it wont bite me.

I think ill try and make it last until the new engine goes in.

mk

 

The lower pin being loose is "vaguely" common. I and someone else here (can't remember who) have had the pin become "unwelded" from the steel plate that is welded to the front end of the rear shaft. The pin can't actually escape because it is captive having a shoulder at the shaft end and the circlip at the other end. BUT having it "unwelded" means it is trying to pivot in the plate everytime you change gear - this makes the gear change very sloppy as the pin works hole in the plate bigger and bigger.

To give you a reference point - I brazed the pin back into the plate attached to the rear shaft, changed the bushings in the rear coupler (back at the front end of the tranny). Now, with the transmission in gear the play at the top of the shift lever side to side and fore and aft is about 2mm. You can actually feel this with the box in neutral as well. So if you have more than 2mm of play at the top of the shift lever (I had maybe 10mm or more before) you know what you need to do.

The rear shaft comes out without all the friggin about you had to on the front one.

 

thats exactly what i have. When i saw it, i said to myself, "great" . Its not that much movement, but like you said, its just the pin in the plate with an end that cant go through and come apart, but when the shifter is pushed the other way loading the springs, you can see it slightly detach and give some lateral play.

that, coupled with the few mm movement of the front ball cup, makes the assembly a little more loose than i would like.

If the rear shaft come out easier, thats good news for the front one as well, as i thought that would be a good way to replace both, from the rear. both have the plate ends that need to be fed through the foam of the shift area. and coming from the rear, a parallel angle could be achieved to get the front shaft through that little bearing that is bolted to the torque tube.

thanks for the info. interesting to see that you have seen that other part of the failing system.

mk

 

Here is the "colar" that the bolt is threaded through and welded to.
I think this is probably stronger than the original part, but we will see!
It sure was a heck of a lot easier to install by the fix, than the new part would have been.

I will have the new part in my racing bag, just in case!


mk

 

I have persoanlly installed one of Carls shift rod securing caps and i can tell this is the only part you will ever want to have on this critical area of the car. One of the big reasons to use this part is so it will never come off unless you remove the lock nut....... NEVER......... NADA . If you read the reason why Carl made this you might realise that the heat from the engine will soften the nylon bushing that seems to fit well when your engine/driveline is cold. Anyway from a racing stand point i would think that you would want the strongest parts on the most critical places. Carls shift rod securing part is the BEST part you can get and it Will NEVER FAIL, I promise, i dont even make these things, But I have seen the quality of the MFG.
Your point about metal to metal is moot , just add some hi temp grease to the ball and the cup will work forever , (Have you ever seen the end of the clutch pushrod, same principle but with a smaller working area)

Im done with this, thanks for your time, Stan