915 – P259 tool measurement request… (With pics)

[Grady Clay]

Murky – yes, my occasional lame brain power.
Sorry for the ‘Senior Moment’

I’ll post a better description tomorrow.

I have the proper P259 tool. The dimension of this tool is 76.5 mm center-to-center.
The P259 is used with the P357 washer.









P357 tool is made up of two parts; the holder I pictured in the above post and
a washer (45x35x2 mm) used to remove all slop except the backlash. This P357
washer is used for all transmissions 901, 911, 914, 915 and 930. Probably more.

and more to come tomorrow … Denver time

Best,
Grady

[sc_rufctr]

Grady

You are the MAN!... That is perfect.

Peter Z

You're last PM with a measurement of 76.6mm was out by .1mm...
That's impressive to say the least.... Well done again!

[Peter Zimmermann]

Originally Posted by Grady Clay

Murky – yes, my occasional lame brain power.
Sorry for the ‘Senior Moment’

I have the proper P259 tool. The dimension of this tool is 76.5 mm center-to-center.
Grady

Grady, I also had a senior moment on this one! I originally pm'd (pm because my tool is homemade) a dimension of 74.6 mm (74.5mm), but in my "moment" I forgot to take into account the over sized axle bolt hole in my tool! Add another 2.0mm and voila!, we have 76.6mm. That is certainly close enough for government work!

By the way, your point to measure at multiple points is a good one. The factory states that two points 90 degrees apart is sufficient, but I don't think that they could guess that we would be building proper transmissions using used components from multiple units!

Peter: Great thread!

[sc_rufctr]

Excellent!

A side question that's not important for my application but would be helpful to our forced induction brothers and sisters...

Is there a specific tool for the 930 gearbox like the Sportomatic version? (P357)
I found a measurement of 90 mm for the turbo gearbox in another thread.

[Grady Clay]

Originally Posted by sc_rufctr

Is there a specific tool for the 930 gearbox ...?[/I]

Yes, there are actually two procedures for the 930/30 and 930/33 transmissions.

The procedure similar to the one for the 901, 911 and 915 uses tools Gauge Holder VW 387, Gauge Measuring Lever VW 388, Adjusting Device VW 521/4, washer from P-357 and Gauge Plunger Porsche 9196. Just like the P-tools above, these can be easily fabricated.

Porsche specifies the lever-arm for the measurement as 101 mm but this is from the edge of the VW 521/4 hex. I need to find the dimension of the hex across the flats and add half that value to the 101 mm.

The specified backlash is etched into the ring gear.

Again Porsche specifies checking at four points 90° apart. I like to rotate the pinion one pinion flat at a time for several revolutions of the ring gear.

With all these transmissions, when checking the backlash around the entire ring gear, you are looking for a pattern that might indicate a deformed differential casting. This will show up as less backlash on one side and more on the other side as the ring gear rotates 360°.

Porsche didn’t make a holder for the 930 pinion nut. Porsche recommends wedging a screwdriver between the case and Reverse Gear III, not to my fancy. I made one like P-249 or P-357.


The other method for measuring 930 backlash is at a tooth tip of Reverse Gear III. The procedure uses the washer from P-357 to lock the differential to the axle flange and two CV bolts driven into the side plate to lock the axle flange to the casting.

Backlash specifications for this procedure are not on the ring gear. Specs are 0.33 ±0.10 mm for the type 930/30 and 0.38 ±0.10 mm for the 930/32. These are equivalent to 0.16 or 0.20 mm at the ring gear.

I prefer the ring gear method.

Best,
Grady

[ed mayo]

Hi Peter, I did remember to measure both 259 and 357 today but Grady has posted his usual excellent answers and photos, so it looks like you're all set ...good luck!!

[Peter Zimmermann]

Originally Posted by Grady Clay

Porsche didn’t make a holder for the 930 pinion nut. Porsche recommends wedging a screwdriver between the case and Reverse Gear III, not to my fancy. I made one like P-249 or P-357.Grady

I love it; there is the right way, the wrong way, and the Porsche way. And I thought that my home-made pinion shaft holder for 915s was crude - it's a thing of beauty compared to a screwdriver!

[sc_rufctr]

My dad used to say... "There's the right way to do something and my way... And they're both he same"

Thanks to all for your input. I can now make a tool that can help verify the backlash of my R&P and confirm if the transmission case is warped or not.

To be honest I'm not really sure I want to know.

[Grady Clay]

There are three basic parts to the ring & pinion setting procedure:
- Setting the pinion position.
- Setting the differential bearing preload.
- Setting the pinion-to-ring gear backlash clearance.

In fact, if you are starting with a transmission or few, you should measure:
- The existing position of the pinion.
- The existing bearing preload.
- The existing backlash around 360°.
- The existing pinion tooth to ring gear teeth pattern.

When you think you are all finished, the final proof is the pinion-to-ring tooth
contact pattern.

Porsche devised the instructions for R&P setting assuming you are
replacing the gear pair with new parts. In our case we are stirring around
used parts, attempting to make them act like new – well, at least work the
best possible.




OK, on to more on measuring ring-to-pinion backlash on a 915. This has
application for 901, 904, 906, 911, 914, 915 and 930. Probably more.

Here is an illustration from the Porsche Factory Workshop Manual.

Overview:
Note P-259a clamping the pinion nut to the input shaft nut, P-259 in place on the axle flange.

© 1971 Dr. Ing. h.c. F. Porsche KG, Stuttgart, West Germany


Here is the P-259 bolted on the axle flange. Note P-259b touching a side cover
rib. Not seen is the P-357 washer installed between the axle flange and the
differential. P-259a or equivalent is holding the pinion stationary. The axle
flange seals and the side cover O-ring are removed. When tightening the side
cover, keep checking for backlash. NEVER, EVER let there be no backlash.
Serious damage will result.

© 1971 Dr. Ing. h.c. F. Porsche KG, Stuttgart, West Germany




Here is pinion bolt clamp P-259 for a 901.

© 1965 Dr. Ing. h.c. F. Porsche KG, Stuttgart, West Germany

Here is pinion bolt clamp P-357 for 905 Sportomatic

© 1967 Dr. Ing. h.c. F. Porsche KG, Stuttgart, West Germany

If you are making your own pinion-clamp tool, it is preferable to build one similar
to P-259 or P-357 above but with a 36 mm socket. There are many circumstances
where you will want to lock the pinion and the input shaft is not installed. The
915 P-259a works great but requires the input shaft to be in place with nut
installed.



Here are all the tools necessary for measuring backlash.



Note the shank of most dial indicators is 8 mm. The bore for the dial indicator
in the P-359 holder is 10 mm. The P-365 is a split adaptor between 8 mm and
10 mm. There are commercial adaptors for this.

I like to use a dial indicator with 0.001 mm minor divisions. While
somewhat ‘jittery’, it allows for good measurement. Like any
precision measurement, it is wise to repeat it several times.

The P-259b Sensor is easily made out of a piece of metal.

Porsche specs a M10 x 110 mm bolt. As you see, I use an old head stud and
some spacer washers. This bolt needs to be tight but not torqued to
the spec 18.8 – 21.7 ft-lbs of the axle flange stretch bolt.

The washer from P-357 measures 45 x 35 x 2 mm. The Factory tool is a hardened
and ground part (complete with ‘P357’ etched on the 2 mm side ). Any nice
flat washer will work. Err on the side of <45 mm, >35 mm and ~2 mm.

You will need the bearing puller for the differential bearings, the centering tool
P-263 for the puller, P-264b and a large selection of differential shims. These
P-tools can be simple 'pipe-tools' and the puller is a commercial tool. The dificulty
is getting a large selection of shims and then what to do with the leftovers.
These are Porsche parts!



Here are all the pieces in place on a 915.

© 1971 Dr. Ing. h.c. F. Porsche KG, Stuttgart, West Germany


Do not use the P-259 dial indicator holder to move the differential back and forth
as shown. Use both hands to rotate the axle flange. Using P-259 as shown can
cause error in readings.



Here is the location of the P-357 washer when installed.

© 1971 Dr. Ing. h.c. F. Porsche KG, Stuttgart, West Germany

Note that the P-357 washer takes up normal running clearance that you can feel
as axle flange (axial) end play.



Backlash specification range for a 915 is 0.12 to 0.18 mm.

The actual backlash for any given ring & pinion is etched on the side of the ring
gear. This is measured with the marked pinion tooth between the two marked
teeth on the ring gear.

The variation in backlash around 360° rotation of the ring gear indicates the
degree that the differential is concentric to its centerline. It should not vary
outside the specification range. If it does, you should replace the differential.


When adjusting the backlash, remember to add size to one side spacer and
subtract the exact same amount from the other spacer. This takes lots of spare
spacers and a micrometer that reads to 0.001 mm. We should illustrate and
describe this part of the procedure. More on this.

When you are satisfied with the backlash, remove the pinion and re-check the
differential bearing pre-load. Reinstall the pinion and do a final check of the
backlash.


Keep in mind that the backlash procedure is almost the final step in the
R&P setting sequence. As a final check you should inspect the pinion tooth to
ring gear tooth contact pattern with a paint substance. This is the subject for
another thread.

Best,
Grady

[David E. Clark]

Fabulous explanation!! Grady Clay is a treasure, what more can I say.

[sc_rufctr]

WOW.... What can I say?

I'm speechless... Grady you're a legend.

So much knowledge sharing and it's done for the best of reasons with nothing to do with the exchange of money...

[911 tweaks]

peter... anything new to report on how you are proceeding and what you are finding out?
Thanks to all for your input here!!
Bob

[sc_rufctr]

Originally Posted by 911 tweaks

peter... anything new to report on how you are proceeding and what you are finding out?
Thanks to all for your input here!!
Bob

Bob

I suspect I have a warped transmission case.
That's the main reason I stared this thread. I can't think of a better way to confirm the integrity of my case and differential.

This is my original thread about my troubled gearbox and differential problems.
915 Shift fork check with an unexpected outcome

Once my tool is complete I will post a pictures of it here with my backlash measurements.

[Joe90]

Did you find the dimension of the VW 521/4 hex ??. I need to find the dimension of the hex across the flats too.. thx

Originally Posted by Grady Clay

Yes, there are actually two procedures for the 930/30 and 930/33 transmissions.

The procedure similar to the one for the 901, 911 and 915 uses tools Gauge Holder VW 387, Gauge Measuring Lever VW 388, Adjusting Device VW 521/4, washer from P-357 and Gauge Plunger Porsche 9196. Just like the P-tools above, these can be easily fabricated.

Porsche specifies the lever-arm for the measurement as 101 mm but this is from the edge of the VW 521/4 hex. I need to find the dimension of the hex across the flats and add half that value to the 101 mm.The specified backlash is etched into the ring gear.

Again Porsche specifies checking at four points 90° apart. I like to rotate the pinion one pinion flat at a time for several revolutions of the ring gear.

With all these transmissions, when checking the backlash around the entire ring gear, you are looking for a pattern that might indicate a deformed differential casting. This will show up as less backlash on one side and more on the other side as the ring gear rotates 360°.

Porsche didn’t make a holder for the 930 pinion nut. Porsche recommends wedging a screwdriver between the case and Reverse Gear III, not to my fancy. I made one like P-249 or P-357.


The other method for measuring 930 backlash is at a tooth tip of Reverse Gear III. The procedure uses the washer from P-357 to lock the differential to the axle flange and two CV bolts driven into the side plate to lock the axle flange to the casting.

Backlash specifications for this procedure are not on the ring gear. Specs are 0.33 ±0.10 mm for the type 930/30 and 0.38 ±0.10 mm for the 930/32. These are equivalent to 0.16 or 0.20 mm at the ring gear.

I prefer the ring gear method.

Best,
Grady

[Jon B]

Originally Posted by Joe90

Did you find the dimension of the VW 521/4 hex ??. I need to find the dimension of the hex across the flats too.. thx

The nominal hex dimension is 32mm; the tool pictured below measures 31.90mm.

This has been the primary backlash tool, since the mid-1970's, for all Porsche transmissions.

A couple of corrections to earlier posts... This tool does not use the locking washer from P357; it uses the Porsche adaptor sleeve 9145. The sleeve P365 is not a metric adaptor, it's an indicator standoff for measuring 905 Sportomatic pinions.

[Grady Clay]

Jon,

Great images – as usual. Thanks.

Using your 9145, the hex is 31.90 mm, then half is 15.95 mm added to the specified “a” = ? to get “b”.

Is “a” = 101 mm?

I think “b” is what Pelican Joe90 is looking for.

Where did the number 101 mm come from?



Best,
Grady

[Jon B]

Grady,

The 101mm dimension is for early 930 transmissions, from the "Turbo Carrera" manual, page 39-17. Yes, that would be added to 15.95 for your "b" dimension in green. The ball on the extension tip is 10mm, so subtract 5mm for the actual measuring distance.

The original 915 manual shows the 901 backlash tool P259 being used, but I question how accurate that can be. The 915 ring gear is larger than a 901 ring gear. The P259 bracket was designed for use on Nadella flanges, and doesn't register on any CV flange. If using the 901 bracket on a 915, it should at least be modified for a different indicating point. The manual recommends doing this to the 905 tool for a 925, but doesn't to the 901 tool.

[Grady Clay]

Time to order a 9145.

For those who haven’t noticed, Jon (Werkstatt) is
one of the resident Pelican P-tool experts (he is not bad
with P-transmissions and photography also ).

Best,
Grady

[Peter Zimmermann]

Originally Posted by sc_rufctr

Update:

I asked an independent Porsche specialist if I could see their tool this morning... "We don't have one and never measure it directly... we do it by feel"

The local Porsche dealership mechanic almost laughed at me when I asked if they would have this tool on hand...

"We haven't rebuilt one of those in more than 10 years" (it's probably being used as a door stop in the toilet)

With all the info in this thread out there for others to use, the above hi-lighted statement is one of the most frightening quotes that I've read! Now, back to our P-xxx tool...

[Jon B]

Pete,

This is a 3-year-old thread that re-surfaced this morning, I just skimmed through it before answering the question. To your point, for anyone doing this measurement, especially a Porsche shop, something adequate should be put together.

Grady, thanks, I like taking pictures . The 9145 sleeve (#10 below) is an adaptor to VW521/4, for use with Porsche differentials. The entire backlash assembly (#10-13) is fairly expensive.