Schnell Gelb

This is an attempt at a nerdy technical thread.
So if you want to make Facebook-type comments please don't be offended if I don't respond. To the Porsche is perfect crowd ,please read no further,this may be painful for you. Fluid Dynamics Geeks however are most welcome
My Getrag 466,6 speed transaxle is out of the car for an engine rebuild so it is an opportunity to work on the gearbox too.
After 90,000 miles it has a little crunch sometimes on 2nd gear and overall is a little noisy. Both are reputed to be common high mileage issues based on my limited study of the 466. This issue is not just with Boxsters but all the vehicles that use this 'box.
I am always interested in the cause of failure and simple prevention. I am not trying to second(that's a pun) guess Getrag - just making a logical deduction from experience.
These seems no way of upgrading 2nd ? So I'll just replace the part.It just seems undersized but it could have been poor cable adjustment too.
The stock bearings are a questionable design -sealed,grease filled and a plastic cage.They belong in a photocopier someone said!
When the trans gets very hot , the grease leaks out of the seals and the unlubricated bearings wear (IMS all over again!). So I would like to use open bearings and DOF (just like IMS).Here is a new product idea for Jake Raby & LN?
My plan would be to create a port on top of the gearbox to which oil from a small Setrab cooler is supplied. An 03-1035 ,3g.p.m. 12v pump from RB Racing will provide flow.The source oil line could be plumbed into the drain plug opening.
Dumping the cooled,filtered oil on top of the gear clusters would ensure(?) plenty of extra splash lubrication to the new unsealed/open bearings.
The oil level in the transaxle would provide a head for the pump.
I am curious to know if the Tracking crowd and 996/997 people make this or a similar mod.Perhaps they have a better idea.Like just using unsealed bearings w/o the complication of a pump/filter/cooler/hoses/fittings=$600+ ! But exactly which bearings to use?
Thanks for any thoughtful,technical responses. I'll add any further info I can find.I just found the full Getrag 466 workshop manual on EBay Germany(i speak German) so that may help me answer questions from others.

Flat6 Innovations

We did this about 5 years ago. In that study we found that directly feeding oil hampered the gearbox bearings just like it did the IMS Bearing. Bearings that are designed to run in grease are much different than bearings designed to run in oil, and if the application will force feed oil, the bearings is again, slightly different.

Because of all that we never brought the products to market. Unlike others, if something proves to be a bad idea, we don't sell it anyway.

Schnell Gelb

Well it seems I am in good company with the idea if not the solution :-).
Just thinking that your IMS experience in changing the bearing spec./design may help move this idea closer to a solution? Who other than Raby /LN know more about upgrading grease-filled sealed bearings? Time to leverage that hard won expertise on the gearboxes,not just engines?
The second gear dog/idler issue for the Getrag 466 is just a $350 part. It is a pity there isn't a 'while we're in there upgrade for the bearings.
I presume that part of the problem is the transaxle acts as a giant air& oil cooled heatsink for the engine. So the traditional Porsche solution would be big air-cooling fins on the transaxle case :-).

Flat6 Innovations

We have already developed the proper bearings for this application. Our distributors had no interest in carrying them, as they were not seeing any components for gearboxes being sold in high enough volumes to warrant adding them to their catalogs.

We have no desire to sell items direct these days and the distributors rule the court with what they can sell. Selling direct is best described as " a disaster".

Again, we did this years ago in parallel with IMSB developments, but unless the demand is large enough there's no use in taking it to market. We just wrote off the development costs and tabled it.

Less than 1/3 of what I develop is ever marketed, the engine parts and processes are no big deal, because we just keep them for ourselves and our engine program, but a tranny part is something we can't use ourselves, because we only build engines.

Schnell Gelb

Jake,
Thank you for taking the time to share your experience. You are one of the very few product inventors who do.
Sad to hear your good work went unrewarded.However I am pleased my question gave you an opportunity to mention your endeavors to your followers on this Forum. If you ever decide to liquidate a few dusty old bearings that you stocked for this project ,I would be glad to purchase on a no warranty/customers own risk basis. Your choice of bearings for your development work on the Getrag 466 would certainly be far better educated than any choice I made on my own !Feel free to contact PM/email me if pursuing my proposal contravenes the Rules of the Forum.
Apparently(?) the bearings (press fit) can only be pulled off the shaft once for replacement before the entire shaft needs to be replaced so I am anxious to choose bearings that would be better than the OEM spec.

Flat6 Innovations

Thank you. I am accustom to having fewer positive experiences than negative. When we hit a home run, it makes up for all the strike outs we have.

Sure, I had forgotten all about my experiences, they were that long ago.

We never release any test components. I have learned not to show our hand to anyone, for any reason. The battles we have fought playing this game have been filled with lessons.

Yes, and the pressing process is a chore in it's self.

Your post spawned an email to our distributors to see if they have had any increased demand for the components since 2007. Lots has changed over the years and its worth asking them what they are seeing in terms of components being sold.

Schnell Gelb

I hope Wayne buys a few from you and writes the instructions for how to press off/on the bearing also !
I am delighted that there is at least a chance of seeing the development work reach an albeit tiny market. I wonder if the number of destroyed engines has created a reasonable supply of 'good used' transaxles ? Unfortunately your successful IMSB fix is 'threatening' that supply :-) !
Now these transaxles are getting more miles on them, the transaxles are failing too and low mileage transaxles are becoming scarcer?That should slowly create a rebuild market? Audi uses the same transaxle so at least that may be a supplementary market for your transaxle bearing fix .

Flat6 Innovations

The issue is the factory bearing is too cheap and not enough people share the mindset that you and I have in regard to doing a job once and doing it the best that it possibly can be.

Flat6 Innovations

I have brought this up to our largest distributor and they do want to revisit the possibilities of carrying these items.

Schnell Gelb

Jake,
I am delighted there is a chance that your persistence paid off.
At least if your gearbox fix is offered, the market can decide if it is worthwhile.
I'll mark that as a potential "assist" by nerdy fluid mechanics geeks to Flat 6 Innovations :-).
Now what about a sequel to The M96 Definitive Guide ? Working title :"The Getrag 466 Definitive Guide" ?
Will either everbe published ?

Flat6 Innovations

We have hop desire in building transaxles. At most the better bearings will be available *maybe* for builders to use. After development I'd have no desire to work with trannys.

My M96 Definitive Guide will be published. I missed a publishing date earlier this spring because I lost my hearing for 4 months and felt horrible. Its been 5 years and ever hold up makes for even more content as we learn and apply more and more.

Schnell Gelb

Yes,I read about your hearing issue.Parrot chatter can be deafening:-).Glad you have recovered.
Sign me up for an early copy of the ever improving book.I'll even volunteer to proof check the galleys !

ltusler

Most SPB racers add a cooler and a pump to circulate the oil, that seems to help them last longer. I just had my 996 trans rebuilt and it showed no signs of heat stress inside, but the pinion bearing was a mess.

Schnell Gelb

Very interesting.If you don't mind perhaps you would tell us all a little more?
- so even though you incurred the expense of rebuilding the transaxle, you did not feel the need to replace the big sealed bearings on the gearshafts?
And the second gear cluster was still good?
What is the secret -cooling ,gear lube ?
The cooler/pump flow -out of the drain hole or from the side of the casing? After the pump +cooler ,the oil is returned via a welded bung on top of the trans case above the gear clusters?
What bearings do they use? Stock with seals or with seals removed?
Thanks - I am really curious to learn from the racers on this issue.

Schnell Gelb

The best compromise I can come up with is to replace the 2nd gear and the bearings with OEM parts but fit a cooler and thermostatically controlled pump.Route the new plumbing fom the drain boss to the filler boss .An early(smaller) Boxster engine oil cooler might look appropriately stock?