Schocki

Central nut was tightened today (450NM), the DIY tranny holder worked very good, no problems. Torqued the bolts that hold the ring to the differential with 165NM.



The loner tool from the truck company MAN, maximum adjustable torque 780 NM .


Ready for final meaurements...

Schocki

Differential housing was installed today, two 0.2mm shims were used and bolts torqued to 46NM.

Measurements were taken multiple times to achieve good results.



1. Diameter of outer differential bearing races 68,0mm (Radius 34,0mm)
2. Aluminium rod was place between the bearing races and adjusted.
3. Telescoping gauge was used multiple times to achieve results with the smallest tolerance possible. Patience is the key to success.
Measured value: 1,6105 inch or 40,906mm
4. Differential bearing race radius 34,0mm + Telescoping gauge value 40,906mm = 74,906mm
5. 74,906mm (measured value) - Inscribed value on pinion 74,88mm = Tolerance 0,026mm (Maximum WSM tolerance 0,05mm)

happy with the results

Next: Backlash adjustment...

Schocki

Backlash adjustment. Not very difficult but you need to be PATIEND! First all bolts have to be torqued to the correct value and the differential needs to be turned 3-4 times before any measurements can be taken.



Measurements have to be repeated every 90 degrees. all 4 values need to be within 0.05mm. The average is the backlash.

Non-corrected values:
0 Degrees = 0.24mm
90 Degrees = 0.23mm
180 Degrees = 0.24mm
270 Degrees = 0.24mm
Average = 0.2375mm



The inscribed value on the ring calls for 0.18mm. This value should not be exceeded and can be 0.05mm smaller. Adjustment is done by adding or removing shims as necessary. IMPORTANT! Total amount of shims or total thickness CAN NOT be changed! Otherwise the differential bearing pre-load is changed!

Corrected values:
0 Degrees = 0.18mm
90 Degrees = 0.17mm
180 Degrees = 0.18mm
270 Degrees = 0.18mm
Average = 0.1775mm

Ready for final assembly



The rest is "Assembly in Reverse Order"

Schocki

The patient has fully recovered and was released today from the liftbars ICU. Test drive later due to seasonal license plate.

Overall it was not very difficult to replace the R&P. But you need some special tools and a shop press. For all you GTS owners: The S4 2.2 R&P is a direct fit and can be used to replace the 2.538 R&P.

Schocki

borland,

FYI the original vent hose has DN5 printed on it. I assume this means it's a 5mm inner diameter hose.

TheoJ

Can't wait to hear if the replacement did solve the problem.
Good job, and very well documented.
regards,

Nicole

Those pictures make me feel like I'm visiting my relatives' transmission factory in Germany (they make transmission for heavy equipment and custom stuff).

Anyway, I admire your diligence to go thorough all that effort for a noise that I certainly never heard during our drive.

I hope there will be no more whining in your car. Tell the kids, too!

Maybe not the best picture, but this was fairly close to Weissach:

Schocki

Hi Nicole,

I will tell the kids
Is your S4 now RMB free?

Schocki

Finally day X arrived, 1. May. The 944 S2 winter Porsche is finally in storage and it's time to take the shark for a test drive.

Battery fully charged and connected, tire pressure @ 40 PSI. All fluids checked and good to go, I turn the key and the engine fires up immediatly and runs smooth. All warning lights are out and the shark is ready to go.

I pull out of my drive way and accellerate slowly to 30, 35, 40 MPH and release the throttle and start cruising under part load. NOTHING!!! No noise!! I do the same thing at different speeds where the old R&P used to whine and it stays absolutely quiet. The only thing I hear is the low voice of my V8.

Life is great!!! All that effort worked out, finally my GTS is like I hoped it would be after the R&P replacement

I only took it for a short spin and so far I can't feel a difference in performance or MPG. I will write some more about it later.

Conclusion: If your GTS whines like mine replace the R&P with a S4 unit, it's worth it!!! I got my R&P used from Mark Anderson and the effort and time is really well spend BTW: It's a 2.2 final gear ratio R&P and they have more in stock .

Thanks Mark for the help and the advice!

Schocki

Quick update

Took the car for a little longer drive today, everything is fine and works as advertised. Due to the longer gear ratio the RPM's are slightly lower, while driving. If I let the car roll at idle, the lowest possible speed is 36 km/h or 22.4 MPH

Gary Knox an others mentioned in this post, that they believe the 2.2 gear ratio is the better choice for the GTS. After driving the car today for a little while I have to agree, the gear ratio feels more suited to the GTS engine with the superior auto box, sorry Roger box.

Hilton

Congratulations on a job well done Shocki, and many thanks for the awesome write-up and photos

Here in Sydney, outside schools at leaving time the posted speed limit is reduced to 40kph and thoroughly enforced. Rolling at 36kph would be pretty funny

Gary Knox

Michael,

I'm so glad the R & P change worked out so well. I'm envious of your skill and perserverance. Wish I had both!! I'm also glad you feel the 2.2 is better gearing for a GTS. Wish Porsche had felt that way!!
Anyway, congratulations on having a truly unique GTS now.

Gary Knox
West Chester, PA

PS: Just returned from ~2 weeks of vacation traveling in Germany (mostly) as well as Austria and Switzerland. ~2K Km of travel, and saw NO 928's on the roads. Saw 3 at Porsche Museum and Porsche Centrum in Stuttgart. I was surprised that it seemed there were more Cayennes on the roads than Porsche "sports cars" during my travels. Auf Wiedersehen.

Schocki

Gary,

928's are very rare here in Germany. I see about 3 cars per year in Bavaria (except on meetings).

Speed an fuel economy update: At 2000 RPM and exactly 64 MPH the instantanious fuel consumption displayed is 9.7 l/100 or 24.24 MPG.

mark kibort

did you use a standard S4 transmission or the GTS gear box with the 2.2 rear end? I read it before, but I dont see the answer with a quick scan of the posts. Actually with the 2.2 on a GTS gear box you would have a very tall gear box. much greater than the 8-10% difference per gear of a GTS vs S4 gear box. (2.2 vs 2.72 which is actualy 25% difference). So, even though the top gear is still the same as it would be in an S4 with a top speed of 225mph gearing-wise, the other gears will be much taller. I think it would be something like :
1st 60mph
2nd 90mph
3rd 130mph
4th 170mph
5th 225mph

But, if you have a standard S4 gear box, which has ideal gears for racing, but a tall gear for commuting to the track .
1st 50mph
2nd 80mph
3rd 118mph
4th 155mph
5th 225mph

dprantl

Are you sure about that? What you have described above is the most awesome gearbox ever for a 928 with 400+ rwhp...

Oh and btw, he has an automatic.

Dan
'91 928GT S/C 475hp/460lb.ft