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After 43 years of working on 928's, I figure that someday, I'll get to the point where I've seen every single idiotic things 928 mechanics can do to one of these cars. Still not true, yesterday.
Maybe after this, there is nothing new to see?
The shop (Kyle) pulled a GT engine, yesterday. Kyle is to the point where he can do this job, in the dark....unless faced with something strange...whereupon he comes and gets me.
He came to me, yesterday, with the problem of not being able to remove the clutch. (We remove the clutch and leave the bell housing behind, when we remove manual transmission engines.)
He told me that the front coupler would not slide back far enough to clear the short clutch shaft....the coupler was hitting the main OD of the torque tube and would not slide back any further.
I told him that some idiot had probably not pushed the torque tube shaft all the way into the transmission and had "missed" the bolt groove in 5th gear aligning with the torque tube shaft (fairly common.) This mistake "pushes" the torque tube shaft too far forward. I told him to look in the rear and see if the "notch" in the torque tube shaft was sticking out of 5th gear and was visible.
A bit mystified, he came back and told me that the "groove" in the rear looked fine.
Now I had to go look....
Turns out that some "expert" had installed the toque tube shaft backwards in the torque tube, when they rebuilt the tube.
Of course, there's a large relief in the front of the shaft for the coupler to be able to move far enough to move towards the rear enough to clear the clutch short shaft.... Rear of torque tube shaft in front of torque tube. No end to what people can accomplish, with a hammer.
and no relief in the rear.....which is why Kyle could not move the coupler back any further.
So, we're sitting there pondering how this idiot/idiots were even able to assemble this mess....
Turns out that the people who installed this mess, simply broke the rear coupler nut off of the coupler and pounded on the coupler until it expanded enough to go over the OD of the torque tube shaft. (This will not show up in a picture, but the witness marks are very visible...I'll take a picture when we remove and throw the shaft in the trash.)
I've never seen this...did not think it was possible!
Is there no end?
Semi-retired, as of Feb 1, 2023.
The days of free technical advice are over.
Free consultations will no longer be available.
Will still be in the shop, isolated and exclusively working on project cars, developmental work and products, engines and transmissions.
Have fun with your 928's people!
Had a few auto TTs show up with backward driveshafts in them. They had a new groove hacked into the front drive shaft splines so the rear pinch bolt could be placed through.
Had a few auto TTs show up with backward driveshafts in them. They had a new groove hacked into the front drive shaft splines so the rear pinch bolt could be placed through.
I haven't seen that, yet.
Something to look forward to!
The stock torque tube shaft is made from a steel that has a very good "memory". While it does twist, it returns back to its' original untwisted position quite well.
Is this piece of steel compromised by turning it around and twisting it in the opposite direction? In simple terms, is this shaft destined to break (as I suspect it is.)
I ask, because torsion bars, in older Porsches, will break if switched from side to side....guaranteed. And axle shafts, in high performance vehicles, will break if switched from side to side.
Someone know enough about this subject to enlighten us?
After 43 years of working on 928's, I figure that someday, I'll get to the point where I've seen every single idiotic things 928 mechanics can do to one of these cars. Still not true, yesterday.
Maybe after this, there is nothing new to see?
The shop (Kyle) pulled a GT engine, yesterday. Kyle is to the point where he can do this job, in the dark....unless faced with something strange...whereupon he comes and gets me.
He came to me, yesterday, with the problem of not being able to remove the clutch. (We remove the clutch and leave the bell housing behind, when we remove manual transmission engines.)
He told me that the front coupler would not slide back far enough to clear the short clutch shaft....the coupler was hitting the main OD of the torque tube and would not slide back any further.
I told him that some idiot had probably not pushed the torque tube shaft all the way into the transmission and had "missed" the bolt groove in 5th gear aligning with the torque tube shaft (fairly common.) This mistake "pushes" the torque tube shaft too far forward. I told him to look in the rear and see if the "notch" in the torque tube shaft was sticking out of 5th gear and was visible.
A bit mystified, he came back and told me that the "groove" in the rear looked fine.
Now I had to go look....
Turns out that some "expert" had installed the toque tube shaft backwards in the torque tube, when they rebuilt the tube.
Of course, there's a large relief in the front of the shaft for the coupler to be able to move far enough to move towards the rear enough to clear the clutch short shaft.... Rear of torque tube shaft in front of torque tube. No end to what people can accomplish, with a hammer.
and no relief in the rear.....which is why Kyle could not move the coupler back any further.
So, we're sitting there pondering how this idiot/idiots were even able to assemble this mess....
Turns out that the people who installed this mess, simply broke the rear coupler nut off of the coupler and pounded on the coupler until it expanded enough to go over the OD of the torque tube shaft. (This will not show up in a picture, but the witness marks are very visible...I'll take a picture when we remove and throw the shaft in the trash.)
I've never seen this...did not think it was possible!
Is there no end?
That's why I prefer to do all the work on my cars myself. I have not worked on as many 928 cars as Mr. Brown has but I have seen several strange faults such as installing the upper front shock mounting upside down.
Åke
The stock torque tube shaft is made from a steel that has a very good "memory". While it does twist, it returns back to its' original untwisted position quite well.
Is this piece of steel compromised by turning it around and twisting it in the opposite direction? In simple terms, is this shaft destined to break (as I suspect it is.)
I ask, because torsion bars, in older Porsches, will break if switched from side to side....guaranteed. And axle shafts, in high performance vehicles, will break if switched from side to side.
Someone know enough about this subject to enlighten us?
I'm only 1/2 engineer type (and 1/2 artist type) but I believe you'll find the shaft turns in the same torsional direction when exchanged end for end.
Last edited by Gage; 07-30-2021 at 08:03 AM.
Reason: added word
The torsion force would be applied in the opposite direction when flipped around.
Nope. Gage is right. It will still be twisting in the same direction. It is kind of like screwing a threaded rod into a nut. You can turn it around and screw it into the same nut from the other end. It still scews in the same direction.
Last edited by Jerry Feather; 07-30-2021 at 10:46 AM.
Nope. Gage is right. It will still be twisting in the same direction. It is kind of like screwing a threaded rod into a nut. You can turn it around and screw it into the same nut from the other end. It still scews in the same direction.
If course it turns the same way but the load is reversed. This of this pen as a shaft with the clip being a spline and let's say it rotates clockwise.
In this orientation, as it spins, first the clip goes by then the logo and the load is on the side of the clip opposite from the logo.
In this orientation, the logo passes by then the clip and the torque load is on the logo side of the clip.
Explain to me where my logic is flawed so I understand it.
There are two things going on. One is the load and the other is the resistance. When you turn it around the resistance is still going the same way as the load when it was turned the other way. There is probably no difference between the load and the resistance.
[QUOTE=In this orientation, as it spins, first the clip goes by then the logo and the load is on the side of the clip opposite from the logo.
No, turning clockwise as we look at it, the load in on the side of the clip next to the logo. It is the same at the other end with the pen reversed, but it is the resistance that is on the same side of the clip as the logo.
07-29-2021, 04:05 PM
Is there no end?
