928 S4 Manual Transmission Questions.
11-12-2011, 08:28 PM
#31
Rennlist Member
just run the rogerbox..........................................
Seriously............how many HIGH hp 928's blow manuals....pretty much ALL OF THEM.... Here is a ?? Name 1 race 928 with STOCK or better HP that completes a full season (12 on track hours) on the same trans................................................................... ........................................................................ ........................................................................ ...
exactly...not even the mighty KIBORT can claim that.....his blew up last year....Anderson breaks them on a regular basis...same for Simard..
leave it stockish...the clutch fails....upgrade the clutch the trans fails
How many ORR cars run automatics with ZERO issues...even with boost....George and Bill have done it for YEARS with no issues....
I have 85.5 hours on track on a rogerbox....that was USED to start with...17 hours in 3 days a few weeks ago... I just changed the trans fluid and filter....and after looking at it + smelling it...it really was a WASTE...still red fluid and no burnt smell at all....I had a YEAR (40 HOURS) of track time on that fluid-filter (normal fluid, nothing special)....however I NEVER-EVER see more than 180F on my trans temps either...a good cooler helps
It really is the "poor mans sequential" for minimal cost....
Okay stepping off the soapbox with flame suit on
Seriously............how many HIGH hp 928's blow manuals....pretty much ALL OF THEM.... Here is a ?? Name 1 race 928 with STOCK or better HP that completes a full season (12 on track hours) on the same trans................................................................... ........................................................................ ........................................................................ ...
exactly...not even the mighty KIBORT can claim that.....his blew up last year....Anderson breaks them on a regular basis...same for Simard..
leave it stockish...the clutch fails....upgrade the clutch the trans fails
How many ORR cars run automatics with ZERO issues...even with boost....George and Bill have done it for YEARS with no issues....
I have 85.5 hours on track on a rogerbox....that was USED to start with...17 hours in 3 days a few weeks ago... I just changed the trans fluid and filter....and after looking at it + smelling it...it really was a WASTE...still red fluid and no burnt smell at all....I had a YEAR (40 HOURS) of track time on that fluid-filter (normal fluid, nothing special)....however I NEVER-EVER see more than 180F on my trans temps either...a good cooler helps
It really is the "poor mans sequential" for minimal cost....
Okay stepping off the soapbox with flame suit on
by the way, my new transmission just lasted the entire season this year.
by the way, the 5th gear shaft didnt go, it was the teath that failed.
oh yeah, scot also worked his stock 82 tranmission for many years too!
11-12-2011, 08:38 PM
#32
Addict
Rennlist Member
Rennlist Member
These are pics taken at 1977 in Porsche factory 928 production line. Notice how there are piles of bare manual gearbox castings for G28/03 waiting to be assembled and people at backround doing it. Individual shafts, gears etc were probably made by subcontractors and possibly even Getrag but gearboxes were put together by Porsche inhouse mechanics. Automatic gearboxes came assembled from Mercedes and differential was added at Porsche factory.
Picture copyright by Edgy01 (Dan). See more in this thread:
https://rennlist.com/forums/928-foru...ne-photos.html
Picture copyright by Edgy01 (Dan). See more in this thread:
https://rennlist.com/forums/928-foru...ne-photos.html
11-13-2011, 12:01 PM
#33
Race Director
ah Brian???? you should know this. the holbert box finally went after 25 years, 8 full racing seasons. (not just one) and with the new motor, with more power, it lasted more than 1.5 seasons. thats 150 hours of hard racing! the motor was 334rwhp for near 8 years , and 375rwhp for the last 3 years.
by the way, my new transmission just lasted the entire season this year.
by the way, the 5th gear shaft didnt go, it was the teath that failed.
oh yeah, scot also worked his stock 82 tranmission for many years too!
by the way, my new transmission just lasted the entire season this year.
by the way, the 5th gear shaft didnt go, it was the teath that failed.
oh yeah, scot also worked his stock 82 tranmission for many years too!
8 years...12 hours per year...96 hours...... I'm at 85.5 in 2 years.....granted at much lower HP....
I do think the weakness of the 5 speed is HEAT....in typical sprint racing formats or at most 30 minutes, they probably won't get all that hot....but endurance racing will test them to the limit, unless a proper cooler is installed....which is what Simard and Anderson did to improve theirs....
Scots doesn't really count since his car rarely sees the track anymore....
It is odd that you stripped the teeth off of 5th gear....must be all that torque
11-13-2011, 05:21 PM
#34
Rennlist Member
Had the GT at the club sprints over the 2 day weekend here in Australia , in 30 degree heat , found that after many sessions , the gearbox found that it wouldnt like shifting into 3rd gear , and all the other gears were very tight .
So with Iceman here , heat is the enemy interesting how the GTS had the cooler , my unit has actually higher output than the GTS did so I would guess that all in all it is still a good design given that hard track work that this registered car has experienced this year.
So with Iceman here , heat is the enemy interesting how the GTS had the cooler , my unit has actually higher output than the GTS did so I would guess that all in all it is still a good design given that hard track work that this registered car has experienced this year.
11-13-2011, 05:40 PM
#35
Nordschleife Master
Is the heat issue perhaps one of diverse expansion rates, aluminum vs steel? If so a very aggressive approach to cooling might be necessary, something active and thermo controlled.
11-14-2011, 06:39 AM
#36
Rennlist Member
I have a GTS box in my racer with the factory cooler. I do 40min races and the box is sweet. Contrary to popular belief, we do get high ambient temps here in the UK every now and then. Still no problem with the box whatsoever...
One area where the 928 is severely lacking is engine oil cooling. The post 1990 design is crap at best and outright dangerous for a race 928 at worst. But that's another topic alltogether...
One area where the 928 is severely lacking is engine oil cooling. The post 1990 design is crap at best and outright dangerous for a race 928 at worst. But that's another topic alltogether...
