Porsche 930 overhaul.

[Paul Bearman]

Just received a Porsche 930 g/box from a Porsche breakers yard in France & I would like to overhaul the unit. Has anyone stripped/rebuilt 1 of these & if so are their any specific points I should bear in mind when taking it apart & rebuilding it?
I have attempted to split the diff housing from the g/box main casing but it only moves by about 2mm. I don't want to force it any further incase I'm mising something. Any help appreciated.

[BruceLambo]

Hi Paul. In the interests of nature and science, can you measure the diameter of the input and output shafts when you have the box to peices? Also the distance between the bearing centres eg: input shaft front bearing to input shaft rear bearing. Oh and also the largest diameter of the pinion gear (the part closest to the bearing).

Cheers

[Russ Noble]

Originally Posted by Paul Bearman

Just received a Porsche 930 g/box from a Porsche breakers yard in France & I would like to overhaul the unit. Has anyone stripped/rebuilt 1 of these & if so are their any specific points I should bear in mind when taking it apart & rebuilding it?
I have attempted to split the diff housing from the g/box main casing but it only moves by about 2mm. I don't want to force it any further incase I'm mising something. Any help appreciated.

Have you taken the end cover off and removed the pinion nut?

Cheers

[Russ Noble]

Originally Posted by RamboLambo

Hi Paul. In the interests of nature and science, can you measure the diameter of the input and output shafts when you have the box to peices? Also the distance between the bearing centres eg: input shaft front bearing to input shaft rear bearing. Oh and also the largest diameter of the pinion gear (the part closest to the bearing).

Cheers

Also the 1st/2nd gear tooth widths!

[Paul Bearman]

I'll start in earnest tomorrow on stripping the 'box & will post the dimensions requested.
Does anyone have expolded drgs of the 930 'box they would be willing to share? Also, I'm still looking for a diif if anyone has one going spare.

[Russ Noble]

Paul, send me an email to russn(AT)paradise(DOT)net(DOT)nz and I will email you some diagrams etc that Eric was good enough to send to me.

Cheers

[Lynn]

Paul,

Go here Road & Race: Parts Charts > Grp III-Transaxle, then select the year range. They have lots of exploded view diagrams.

Lynn

[Paul Bearman]

Russ, Lynn
Many thanks for your help.

[DCraig]

I have rebuilt way over a hundred of them. Take off the cover plate on the bottom and inspect the engagement teeth and synchro rings. Anything further will reqire a teardown.

[Russ Noble]

Tirebiter,

Welcome to the forum. You're not the D Craig who had/has a 911 with, I think, a 427 or similar and 930, that was stolen last year? Special welcome if you are!

I have been looking for information on the 'drop through' test for the case bearings on 930's. Specifically measurements for the mandrel that is used, or maybe buy one from a retired Porsche mechanic?

Cheers

[DCraig]

Originally Posted by Russ Noble

Tirebiter,

Welcome to the forum. You're not the D Craig who had/has a 911 with, I think, a 427 or similar and 930, that was stolen last year? Special welcome if you are!

I have been looking for information on the 'drop through' test for the case bearings on 930's. Specifically measurements for the mandrel that is used, or maybe buy one from a retired Porsche mechanic?

Cheers

Yep, one and the same, and thanks for the welcome.
I've only seen go/no go gauges for the needle bearings that ride on the input shaft and pinion shaft. The needle bearings that are pressed into the case
would fail inspection only for cage breakage or severe bearing pitting/corosion. Those case bearings support shafts that no not rotate at high speed.

[Russ Noble]

Originally Posted by Tirebiter

Yep, one and the same, and thanks for the welcome.
I've only seen go/no go gauges for the needle bearings that ride on the input shaft and pinion shaft. The needle bearings that are pressed into the case
would fail inspection only for cage breakage or severe bearing pitting/corosion. Those case bearings support shafts that no not rotate at high speed.

OK Tirebiter, I must have got it wrong with regard to which bearings the test was relevant to. Do you have the measurements for the go/no go gauges, or alternatively got a set for sale? Thanks for the info on the case bearings.

Good to have you on the forum, maybe you could post some photos of your Porsche on "The Paddock"? Not the sort of thing we see much of down under.

Cheers,

[DCraig]

Originally Posted by Paul Bearman

Just received a Porsche 930 g/box from a Porsche breakers yard in France & I would like to overhaul the unit. Has anyone stripped/rebuilt 1 of these & if so are their any specific points I should bear in mind when taking it apart & rebuilding it?
I have attempted to split the diff housing from the g/box main casing but it only moves by about 2mm. I don't want to force it any further incase I'm mising something. Any help appreciated.

Rear cover plate and hockey stick (shift rod ) cover plate must be removed first. Then take off the pinion nut and remove the large reverse gear. Center section will then slide off.

Remove the input shaft nut and use a big two jaw puller to remove the end bearings by pulling on the gear behind each one.

Then remove the two 17MM hex head bolts and the spring and detent pill behind them. This allows you pull the shift fork shafts back as you pull each individual gear. DON'T loosen the adjusting nuts on the shift fork shaft or you will need a factory tool to adjust them. Tap them back and you will save your factory adjustment setting.

I'll measure the shafts and gear widths before I leave town and post them.

[Jim S.]

D Craig,

Great info. Keep it coming. When you rebuild one who's the best source for parts. How's Pelican Parts? What part of the syncros is typically bad and do you replace with stock parts?

Are there any parts that should be replace with beefer parts such as the cast steel bearing retainer plate?


thanks for you input.

[DCraig]

[quote=Jim Sheren;187908]D Craig,

Great info. Keep it coming. When you rebuild one who's the best source for parts. I have lots of NOS (new old stock) ZF parts from the racing days and my PorschaSports shop owner days. I also use SSF Wholesale and Performance Products for parts. OEM only. No Italian, British, or Brazilian crap. I married into the Behr family and Frau Behr ran Porsche Motorsports Racing for many years so I have some "pull" there if I get in a parts bind. Diter Kirschner worked for ZF until he retired but I can sometimes coax him into hand fabricating parts for me that are no longer available. Diter is older than most rocks now so it's tough even to ask him.

How's Pelican Parts? I have never used Pelican and therefore have no first hand information to offer about them.

What part of the syncros is typically bad and do you replace with stock parts? The synchro ring is replaced while the expanders and anchor block is reused unless damaged. This can be done by hand and requires no tools once the gear is off the shaft. The engagement teeth (sometimes refered to as "dogs"), and the shift fork sliders are replaced if their sharp little points are worn down or worn off. Look carefully at the first picture of a 935 box before rebuild. On the bottom bitter end is the first gear set and the teeth are sharp and good. Next is second gear and the teeth show flatted points. Gotta be replaced. On the upper shaft is third gear with sharp teeth. Fourth gear has no points at all due to a driver jamming into fourth without using the clutch. Pro drivers are an uncaring, brutal lot, eh?
A special is tool used to press the engagement teeth off the gear and the new teeth are heated to 350*F and dropped onto the frozen gear. Tap it quickly into place with a small brass hammer until it seats flat. Seat it quickly or you must start over again.

Are there any parts that should be replace with beefer parts such as the cast steel bearing retainer plate? The steel bearing retainer plate is a non moving part and never wears out . Now and then under high torque and HP conditions, the ring gear cover plate gets pushed out and is replaced by a custom made aluminum billet plate.

[DCraig]

Originally Posted by Russ Noble

Tirebiter,


I have been looking for information on the 'drop through' test for the case bearings on 930's. Specifically measurements for the mandrel that is used, or maybe buy one from a retired Porsche mechanic?

Cheers

The "drop through" gauge is pictured below. This is used to check the O.D. on the needle bearings that ride on the input and pinion shafts. They are not used on the bearings pressed into the case.

The measurement at the top is 43.80mm; the measurement on the bottom of the taper is 43.40mm. This puppy is very temperature sensitive and should be used between 64*F to 80*F. It has four tapped holes to insert bolts to keep it from gaining heat from the surface it might be sitting on. I use styrofoam. Just for grins I took a known good bearing and let the gauge heat in the sun untill it reached 100*F. Zoom, it passed right through.

There is also a drop gauge used to check the I.D. on the needle cage bearings but it's a joke. Gentle pressure on the inside of the bearing will pop out any needle held by a weak cage.

Both gauges and the 385 tool are pictured also.

DC

[Russ Noble]

Hmmm......That's a bit tricky! Not at all like I'd imagined. Guess I won't be making that in a hurry! Thanks DC, for taking the trouble to post though. Very interesting.

Cheers,

[DCraig]

Originally Posted by Russ Noble

Hmmm......That's a bit tricky!
Cheers,

On top of being tricky to machine, it's made of titanium. Titanium has a low coefficient of linear expansion.