9284VR

Hi all!

Technical quizz for you, wizards of the 928

Who ever switch it's 90 GT gear box for a GTS one? It's not only an upgrade question, but also an opportunity to cure a weak one.
How far the oil radiator would fit that swap?
Looks like the parts number are differents, according to the PET

Thanks for your help!

Michel

MikeN

I personally don't see much advantage to the swap. The GT trans is not "weak" to my knowledge but Porsche did add an oil cooler to the GTS model. The final drive ratio is also the same.

9284VR

Hi Mike!
I must be clear at that point: I do enjoy my '90 gt trans, but the problem here comes from another car.
It's owner is about to fix the gear box, as problems would soon appear.
He's got the opportunity to get a GTS gear box in good shape.
Now, the question is: would he have a better time fixing it's original gear box, or should he go for the swap?

Thanks for your answer, anyway

Michel

Jim bailey - 928 International

The GTS box is supposed to be stronger the gears are treated and the oil cooling helps when heavily loaded.

dan davies

it is a lot stronger

MBMB

Welcome to the list, Dan. With all due respect, what are the bases of your assertion? Lots of folks here want to know more about the 928s, and "it is a lot stronger" doesn't add diddly-squat to our knowledge.

Jim bailey - 928 International

How about " reinforced drive shaft /drive pinion bearings,improved countershaft needle roller and cage assembly, ground drive pinion/ring gear assembly,Oil deflector/drilled drive pinion , transmission spur gears new material 17crnimo6 suitable for higher continuos loads in addition surfaces of the loose and fixed gear faces has been compacted by wire shotblasted to increase load capacity even further." as of the 1992 year

MBMB

That's what I'm talkin' 'bout.

puyi

Ok so GTS trans is much stronger yhan GT.
The fact is that our friend (9284VR and me) who "enjoy" GT trans problem is wondered if it is possible to mount a GTS gearbox in place of the GT one without major issue.
To be completely clear, he is facing an alternative 1- buy a GTS gearbox in good shape for relatively low price 2-rebuild his GT one , simply but costly.

Thousands thanks for the help

STL

Vilhuer

I know it works other way around as one GTS has GT box in it now while GTS box is waiting for rebuild. It shouldn't be too large problem to install GTS box into GT.

If aim is to make it exactly like GTS then it gets little complicated as cooler need to be added to front of radiator. This is same part as what is used in automatic gearbox S4 (at least last years) and GTS. To be able to mount it at the front other parts might need to be changed also. PET should help listing what these are.

Other option would be to install custom oil cooler somewhere and connect GTS box oil lines to it. Where exactly this could be installed is other question.

What ever gearbox you end up using please replace these two parts when you have cover open.
928 303 034 09 Spring
928 303 287 01 Leaf Spring
First is flat steel spring that makes gear lever stay in the middle. Second is reverse lock spring. These both crack and break after surprisingly little use and can cause very serious damage if one is unlucky. Reverse lock works somewhat ok even when spring is broken though but it can sometimes allow lever go to reverse when you least expect it.

9284VR

Thanks for you help
Ok, now, I've got the picture, GTS trans is stronger... but has anyone swapped it into a GT, whithout any nervous breakdown? Sounds that's a very good tip for someone who would race it's 928... only if it's doable...

Michel

Vilhuer

It is doable and even not too hard, there's no question about it. It's just what else needs to be changed in front of engine to be able to add gearbox oil cooler in there. Gearbox itself is direct swap. All mounting points etc. are exact same.

Jim bailey - 928 International

It is a direct bolt in the only extra thing is if you make the oil cooling functional . You could simply recirculate the oil with no cooler or as mentioned add the necessary parts to make it fully functional but even with the oil not being cooled it is a stronger gear box.

9284VR

Thanks guys for these precious informations

Now, there's a precise fall project on its track for our friend...

Keep on sharkin'

Gnarly 928

The GTS has a bigger torque tube tunnel. I sold a pair of SRD Recarro sport seats to a friend with a GTS, the seats just came out of my GT. They would not fit into his GTS because the floor of the car has a larger tunnel...So perhaps the GTS tranny will not fit into a GT..I can't see Porsche changing the whole bottom of the car unless it was needed when they started the GTS production run.
Extra transmission oil cooling seems to be a very good idea. I was seeing oil temps in my GT trans approaching 300F! With my mocal cooler and tilton external pump, I keep the temps at 180F and so far have improved the dependability of the gearsets on the track. Not that big a job to install that tranny cooler, mine fits behind the passenger rear wheel.
Don Hanson