968 Gearbox Alternatives?
10-29-2013, 03:53 PM
#1
Rennlist Member
Thread Starter
968 Gearbox Alternatives?
CROSS POST FROM 968 SIDE
Early this past weekend while at NJMP racing with NASA, something broke in my gearbox and I lost the ability to go into 1st and 2nd. I am told that it possibly has to do with a synchronizer hub.
But given that I have always complained about the gear ratios while secretly wishing for a sequential... this may be the right time to look at options.
Any reasonably priced aftermarket racing gearboxes or transplant alternatives out there?
Thanks in advance...
Early this past weekend while at NJMP racing with NASA, something broke in my gearbox and I lost the ability to go into 1st and 2nd. I am told that it possibly has to do with a synchronizer hub.
But given that I have always complained about the gear ratios while secretly wishing for a sequential... this may be the right time to look at options.
Any reasonably priced aftermarket racing gearboxes or transplant alternatives out there?
Thanks in advance...
10-29-2013, 04:08 PM
#2
Race Car
Hey Pablo....., you and I traded a few emails about trying to land a garage to share at COTA earlier this year.....anyway, I have a very low mile stock 968 box from a totaled cab with open diff ( you could transfer your LSD).
PM me if interested.
T
PM me if interested.
T
10-29-2013, 11:41 PM
#4
Rennlist Member
Hi Pablo
There’s really not a lot of alternatives out there. Regarding the ratios, what do you find is the problem with them? I know with a forced induction motor they’re not bad but would you want shorter ones than stock? If so, I am pretty sure that cogs from 911’s will fit as the LSD is the same size as from a G50 gearbox. Going the SQ route is not easy. I’ve explored it quite a lot and it will be expensive no matter which way you go. There is a 944 turbo down here that has an Albins sequential but from what I understand this was a very costly upgrade by the time all the fab-work was done.
It’s a shame but we just don’t seem to have many options with the front engine Porsches.
There’s really not a lot of alternatives out there. Regarding the ratios, what do you find is the problem with them? I know with a forced induction motor they’re not bad but would you want shorter ones than stock? If so, I am pretty sure that cogs from 911’s will fit as the LSD is the same size as from a G50 gearbox. Going the SQ route is not easy. I’ve explored it quite a lot and it will be expensive no matter which way you go. There is a 944 turbo down here that has an Albins sequential but from what I understand this was a very costly upgrade by the time all the fab-work was done.
It’s a shame but we just don’t seem to have many options with the front engine Porsches.
10-30-2013, 07:17 AM
#5
Race Car
A few things. First, check the shifter and all of that to make sure it actually is external. You may have, but check the simple things, first. Odd that 1st and 2nd, which are almost never used would be the ones to go. Anyway, watch out for what changes would do to your class. If you are going to stay NASA, no biggie. Looking at your car, I think you'd go right into SP3. You can change ratios there, but you can't change to a different type of gearbox. This thread may be of interest to you: Custom R&P gearing for 968
10-30-2013, 10:36 AM
#6
Three Wheelin'
Keep in mind that if you put a non-Porsche gearbox in the car, I believe it won't be legal for PCA club racing ...
I'd think your best bang for the buck in replacing the trans would be rebuilding yours or finding a reasonably priced replacement.
I'd think your best bang for the buck in replacing the trans would be rebuilding yours or finding a reasonably priced replacement.
10-30-2013, 12:17 PM
#7
Rennlist Member
Your problem with 1st and 2nd gear is common for the 01E transmission used in the 968 series. The syncro hub (aka operating assembly) design is different from that used in the 944-series. If you grind dog teeth when shifting the 01E, they peen in a way that inhibits operation (sliding the syncro hub). I've serviced a few of these, the immediate solution is to replace the hub. The longer term solution is to do a better job shifting!
Kevin
Catellus Engineering
Kevin
Catellus Engineering
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10-30-2013, 01:16 PM
#8
Race Car
Porsche calls the assembly he'd need a 'synchroniser hub' because the assembly includes the actual hub and the individual parts are not available separately.
Technically, the failed part in Pablo's trans is the sliding sleeve and/or not, 1st and 2nd speed "loose gears" (may even be just a damaged fork) but you can't source the sliding sleeve without the hub, which is a non moving part and never/rarely fails.
These two gears are the heaviest mass of all syncho'ed gears in this trans so the speed match duty of the syncrho ring and teeth will be the hardest on this set.
In a racing app, lightening the gears would surely pay dividends in prolonging a failure interval.
Pablo, I'm out the door on a mission for work but I will post a pic of the trans and PM you back to answer your question..
T
Technically, the failed part in Pablo's trans is the sliding sleeve and/or not, 1st and 2nd speed "loose gears" (may even be just a damaged fork) but you can't source the sliding sleeve without the hub, which is a non moving part and never/rarely fails.
These two gears are the heaviest mass of all syncho'ed gears in this trans so the speed match duty of the syncrho ring and teeth will be the hardest on this set.
In a racing app, lightening the gears would surely pay dividends in prolonging a failure interval.
Pablo, I'm out the door on a mission for work but I will post a pic of the trans and PM you back to answer your question..
T
10-30-2013, 03:49 PM
#9
Rennlist Member
Thread Starter
Thanks guys!!!
Patrick: I'd love to have a shorter 4th, 5th and 6th. I believe this would work wonders for my low power application. The problem is that they seem to be very expensive.
Indeed King... Did check linkage and, without disassembly at this juncture, we are 99.9% sure it is internal. I saw that thread... R&P swap is also an option... Investment vs. gains is somewhat marginal to some degree... I have continued to move farther away from SP3 due to aero, and likely will campaign GT5S again next year if I come back to PCA CR...
True that 914. I would want to keep it a Porsche box to stay compliant in PCA.
Thanks Kevin... 1st and 2nd have complained for a while when not babied... Its a shame because comparatively speaking these are rarely used while racing... I used 2nd on and off at Daytona last year in the infield and it got worse as the weekend progressed. Then at CMP I used it once a lap and the box just was not liking it... Around the paddock on Friday this past weekend, seemed like unless ultra slow shifts, grinding seemed to have gotten exponentially worse by the shift... Then after coming to a stop in T5 after a two-car incident, I could not get it into 2nd or 1st to get re-going... After that, the "gear options" disappeared for good...
Thanks T; I believe you are spot-on...
I guess my decisions pivots on two options:
1- buy a used gearbox and swap diffs
2- Open mine up for repair and recondition and possibly make the added "investment" in shorter gears past 3rd or 4th and above...
Patrick: I'd love to have a shorter 4th, 5th and 6th. I believe this would work wonders for my low power application. The problem is that they seem to be very expensive.
Indeed King... Did check linkage and, without disassembly at this juncture, we are 99.9% sure it is internal. I saw that thread... R&P swap is also an option... Investment vs. gains is somewhat marginal to some degree... I have continued to move farther away from SP3 due to aero, and likely will campaign GT5S again next year if I come back to PCA CR...
True that 914. I would want to keep it a Porsche box to stay compliant in PCA.
Thanks Kevin... 1st and 2nd have complained for a while when not babied... Its a shame because comparatively speaking these are rarely used while racing... I used 2nd on and off at Daytona last year in the infield and it got worse as the weekend progressed. Then at CMP I used it once a lap and the box just was not liking it... Around the paddock on Friday this past weekend, seemed like unless ultra slow shifts, grinding seemed to have gotten exponentially worse by the shift... Then after coming to a stop in T5 after a two-car incident, I could not get it into 2nd or 1st to get re-going... After that, the "gear options" disappeared for good...
Thanks T; I believe you are spot-on...
I guess my decisions pivots on two options:
1- buy a used gearbox and swap diffs
2- Open mine up for repair and recondition and possibly make the added "investment" in shorter gears past 3rd or 4th and above...
10-30-2013, 08:21 PM
#10
Pro
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You might find this Audi O1E gearbox cross reference page useful. Check out the links on the Audi page for more info
http://12v.org/urs/charlie_smith/01E/index.htm
968 references
http://12v.org/urs/charlie_smith/01E/ind3.html
From the site:
"I've found that Porsche no longer stocks the 1/2 shift operating sleeve
for the 968 transmission. Since this is a part that fails, this leaves
the 968 owner needing to replace the entire transmission when this part
fails! Porsche no longer even lists a part number for this piece.
It turns out that the 2WD version of the Audi 01E transmission uses the
same part, and Audi has the part number listed.
The part number you need is 01E 311 239 E - this is the 1/2 shift hub
and operating sleeve."
http://12v.org/urs/charlie_smith/01E/index.htm
968 references
http://12v.org/urs/charlie_smith/01E/ind3.html
From the site:
"I've found that Porsche no longer stocks the 1/2 shift operating sleeve
for the 968 transmission. Since this is a part that fails, this leaves
the 968 owner needing to replace the entire transmission when this part
fails! Porsche no longer even lists a part number for this piece.
It turns out that the 2WD version of the Audi 01E transmission uses the
same part, and Audi has the part number listed.
The part number you need is 01E 311 239 E - this is the 1/2 shift hub
and operating sleeve."
Last edited by car_slave; 10-30-2013 at 08:29 PM. Reason: added more info
10-30-2013, 08:48 PM
#11
Race Car
Here's the transmission Pablo.
Before a friend closed a German car resto/resale shop about a year ago, I used to trade repairing transmissions on high end cars he'd purchase for resale.
Most times, I'd just take my pick of some pretty desirable parts as payment.
I took this trans from a 30k mi. cab probably 10 years ago.
It currently resides in a 944T GT3 car that I have been building on the back burner for several years but never turned a wheel.
The latest twist is that I am probably returning this car to more near stock for an E or SP3 car for my son, so I don't need it.....and a host of other parts that are part of this 95% complete car.
Sent PM also.
T
Before a friend closed a German car resto/resale shop about a year ago, I used to trade repairing transmissions on high end cars he'd purchase for resale.
Most times, I'd just take my pick of some pretty desirable parts as payment.
I took this trans from a 30k mi. cab probably 10 years ago.
It currently resides in a 944T GT3 car that I have been building on the back burner for several years but never turned a wheel.
The latest twist is that I am probably returning this car to more near stock for an E or SP3 car for my son, so I don't need it.....and a host of other parts that are part of this 95% complete car.
Sent PM also.
T
