5 speed or 6 speed?
11-12-2006, 07:45 AM
#16
Drifting
porsche set up the early 968 with too much pinion bearing preload, which caused premature falure of the bearings. this problem was resolved in 94 when porsche used less preload. and they arnt g50 C&P.
11-12-2006, 08:36 AM
#20
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Originally Posted by Porschefile
In the US, who the F really drives 200mph?! 
Seriously, lets be realistic here. Top speed is not that important. If you lived in Germany it would make more sense. Here, ~150mph is more than enough to have fun and put you in jail, plus you'd get the added benefit of acceleration as opposed to a FD capable of 2 million mph.
Seriously, lets be realistic here. Top speed is not that important. If you lived in Germany it would make more sense. Here, ~150mph is more than enough to have fun and put you in jail, plus you'd get the added benefit of acceleration as opposed to a FD capable of 2 million mph.You don't spend enough time on Supra forums... those guys are constantly running up to 170-180.
Rogue
11-12-2006, 09:10 AM
#21
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Originally Posted by special tool
Yes - friend of mine has a 968 with an S2 R&P - but that is crazy and so is he.
Porschefile- yes, it is stronger- this is part of the reason for the better weight dist of 968's over 951's too (not to mention the lighter 968 engine & lack of IC up front)- still, a beefier transaxle. The "failure" was just as JET951 said- there was some sort of "silent" recall on that one...
As for "who needs to drive 200 on public roads," well, who NEEDS a 500+HP ANYTHING on city streets? For that matter, who NEEDS a motorcycle that's capable of running the 1/4 in well under 11 seconds? Who NEEDS a 6000+lb SUV for their DD...? I mean, think about it. As for breaking 200, it's really the Holy Grail & when you've got HP like Defastest, you actually have the potential, so why not maximize it when you're already having to buy new parts?
As for gearing- w/D's power levels, going any shorter than stock 951 gearing is almost counter-productive. Look at the gearing of the Vettes & Vipers- they're BOTH really TALL & get away w/it b/c of their incredible low-end TQ & HP. D's HP/TQ:weight is even stronger
The GTSR had an evenly-spaced 6-sp where 1st hit 60mph & 6th was capable of 300MPH!!! Their best bang for the buck mod is a shorter (higher number) R&P. The usual one shortens their gearing ~20% & 6th is STILL capable of 240 & 1st ~50mph! The real benefit of a 6-sp is being able to push the gears together a tad closer & still have a slightly taller top gear- best of both worlds- just like going from a 3-sp to a 4-sp, or from a 4-sp to a 5-sp.This is part of the reason why many autos are slower than many manual's- many auto versions have one less gear, like a more spaced 4-sp instead of a 5-sp manual... Also, turbo's like taller gears- oftentimes turbos will run through the first few gears before the turbo really gets a chance to spool-up. Turbo's like to get into a gear, load-up, & ring it out for a few seconds. There are many variables, but, for a car w/~550HP, why not....?
Last edited by Robby; 11-12-2006 at 09:36 AM.
11-12-2006, 10:52 AM
#22
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I can confirm you don't need to change torque tube etc. - I've that other places too - not sure why.
I take my 968 box in and out all the time....too often...and no problem.
Obviously the speedo issue and one of the half shafts needs to be changed out to 968 b/c its longer on one side b/c of trans design....can't remember which side.
I can also confirm the preload problem, but it is easily fixable when apart.
Beyond that I'm only good for "I've heards" but from pretty reliable soources
I've heard they're stronger....to stand up to the 3L torque
I had a LSD put in mine, I believe a G50 & I think its a clutch type and I know it is set to 40% but can also be set up for 80%, I think 80% would be too much for a st. car, I don't break the 40% very often but car sees limited track time
I've heard a Paul Guard LSD is the way to go....expensive....strong chromoly case and other trick goodies...there is a good article out there by Paul Guard on LSDs....he says the torque biasing type is inferior
I really like the box, the rpms don't drop off so much in b/w shifts so it seems easier to me to stay in good boost range
All this said, the fastest 951 track guys I know run either NA or S2 trans', I don't know the ratios but supposedly they are shorter set ups...I am sourcing an S2 now for a track 951 I am in the process of building up. I know guys who break the NAs pretty often....maybe weak?...but they just change them out...NA trans' are a dime a dozen.....968s on the other hand....I think getting harder and harder to find
Anyone have the NA and S2 ratios and/or experience w/ them ?
Me personally, even in my st. car, I'd rather be short and fast to 150 than stretched out and long to 170...I know some GT-3 nut cases who obsess over gear stuff....it is the real math behind the final go to the wheels...some of them change gears but I've heard changing the R&P is the better way to go....again these are some GT-3 guys I know....they are all about fast to 150 range and cost isn't a big issue for them either
I take my 968 box in and out all the time....too often...and no problem.
Obviously the speedo issue and one of the half shafts needs to be changed out to 968 b/c its longer on one side b/c of trans design....can't remember which side.
I can also confirm the preload problem, but it is easily fixable when apart.
Beyond that I'm only good for "I've heards" but from pretty reliable soources
I've heard they're stronger....to stand up to the 3L torque
I had a LSD put in mine, I believe a G50 & I think its a clutch type and I know it is set to 40% but can also be set up for 80%, I think 80% would be too much for a st. car, I don't break the 40% very often but car sees limited track time
I've heard a Paul Guard LSD is the way to go....expensive....strong chromoly case and other trick goodies...there is a good article out there by Paul Guard on LSDs....he says the torque biasing type is inferior
I really like the box, the rpms don't drop off so much in b/w shifts so it seems easier to me to stay in good boost range
All this said, the fastest 951 track guys I know run either NA or S2 trans', I don't know the ratios but supposedly they are shorter set ups...I am sourcing an S2 now for a track 951 I am in the process of building up. I know guys who break the NAs pretty often....maybe weak?...but they just change them out...NA trans' are a dime a dozen.....968s on the other hand....I think getting harder and harder to find
Anyone have the NA and S2 ratios and/or experience w/ them ?
Me personally, even in my st. car, I'd rather be short and fast to 150 than stretched out and long to 170...I know some GT-3 nut cases who obsess over gear stuff....it is the real math behind the final go to the wheels...some of them change gears but I've heard changing the R&P is the better way to go....again these are some GT-3 guys I know....they are all about fast to 150 range and cost isn't a big issue for them either
11-12-2006, 11:18 AM
#23
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944NA FD's were 3.889- the S2 is 3.875.
Check out Danno's Racer X site- here is a link- if it doesn't get you straight to the page, then look on the left for "924/944 gear ratios" or something- you'll find it...
http://members.rennlist.com/951_racerx/
Check out Danno's Racer X site- here is a link- if it doesn't get you straight to the page, then look on the left for "924/944 gear ratios" or something- you'll find it...
http://members.rennlist.com/951_racerx/
11-12-2006, 02:20 PM
#24
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If you can do it, I would look real hard at putting the 951 R&P into a 968 box. That would give you the taller first you want and raise the top speed at 6500 rpm by about 10 mph. Check out 968.net for stories about the 968 R&P failure, I don't think it was ever fixed during production. It is kind of a crap shoot. Replacing the R&P with the 951 gears would of course correct any potential problem.
On the other hand, with that engine you don't really need six gears. But like someone above said, it is not about what you NEED.
Lou
On the other hand, with that engine you don't really need six gears. But like someone above said, it is not about what you NEED.
Lou
11-12-2006, 08:22 PM
#25
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The 968 box is way superior, the gear change is much better, and it is a much beefier unit.
Custom R&P are available, you are pretty good if you can get a 951 piece i there, very good..
First gear is pretty similar to the 951, sixth is pretty close to 5th, 2-5 are closer.
Custom R&P are available, you are pretty good if you can get a 951 piece i there, very good..
First gear is pretty similar to the 951, sixth is pretty close to 5th, 2-5 are closer.
11-12-2006, 08:32 PM
#26
Three Wheelin'
Originally Posted by Rogue_Ant
You don't spend enough time on Supra forums... those guys are constantly running up to 170-180.
Rogue
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Uh, actually I do. I practically live there(lurking mostly, tons of good turbo-related info there)!
Consider the source. There are quite a few of those guys running well over 800-1000+hp. Once they actually hook up, running up to 180mph or so goes by fairly quick. There's a "little" bit of a difference of acceleration between that and a 500hp 4cyl. The longer it takes you to get going that fast, the more likely you might get caught by a cop. I'm sure DFastest can get away with it occasionally due to his location, though that's still a little crazy IMO and there aren't too many areas in this country where you can get away with that. Personally, I'd rather optimize my car for acceleration to a max of say ~150-160mph as I rarely ever drive that fast. Oh well, to each his own. Hell, I've even seen a lightly modded (power-wise) Integra with custom gearing setup to do 195mph (salt flat car, or some other kind of competition), but it probably took him 0-195mph in about 2hrs! It takes all kinds.
11-12-2006, 08:39 PM
#27
I have had the 968 up past 150 mph and it showed no signs of slowing down. I cut back because I didn't want to go any faster. I was told that the car would peg the speedo at 180. I can't confirm though because I haven't taken it there and I don't know what the RPM was at 150 in top gear. I also don't know what, if anything, has been done to the tranny.
11-12-2006, 10:06 PM
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Sorry if I sound like an idiot. Let's see if I got this straight.
The 968 is better, stronger. I can put my 951 fifth gear in place of the 968 sixth? This would get me better top speed? The first gear in the 968 is a bit taller? I was told the sixth gear is taller than the 951's fifth. So I'm a bit confused. I would like to have the 968, have a taller first and sixth. Can I still use the gears I need out of my tranny? You tell me.
On the differential, what are you guys talking about with torque bias and clutch type? I have no idea what you are saying or talking about. Sorry for being an idiot but that's why I'm on these boards. I have an 89 Turbo S differential. Am I good? I can keep my torque tube?
Oh, and the top speed. I'm not on the Supra forums but I see and run with them all the time. I get on my car like I stole it putting as much distance between me and them until they spool up, then they pull me in but by the time they catch me I'm doing 165-180 depending on the car. If you haven't been out here this new beltway is undeveloped and we run the hell out of it. I actually found my top speed of 194mph on this beltway.
The 968 is better, stronger. I can put my 951 fifth gear in place of the 968 sixth? This would get me better top speed? The first gear in the 968 is a bit taller? I was told the sixth gear is taller than the 951's fifth. So I'm a bit confused. I would like to have the 968, have a taller first and sixth. Can I still use the gears I need out of my tranny? You tell me.
On the differential, what are you guys talking about with torque bias and clutch type? I have no idea what you are saying or talking about. Sorry for being an idiot but that's why I'm on these boards. I have an 89 Turbo S differential. Am I good? I can keep my torque tube?
Oh, and the top speed. I'm not on the Supra forums but I see and run with them all the time. I get on my car like I stole it putting as much distance between me and them until they spool up, then they pull me in but by the time they catch me I'm doing 165-180 depending on the car. If you haven't been out here this new beltway is undeveloped and we run the hell out of it. I actually found my top speed of 194mph on this beltway.
11-12-2006, 10:59 PM
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Hey man- yes, it can get confusing- 6th in a 968 IS taller than 5th in a 951, BUT, when combined w/the 968 FD (R&P or whatever) it becomes shorter. To get that #, the total, you simply multiply- this gives you the Overall Ratio- So, a 951 is a .83 w/3.375FD, so it's 5th gear OR is a 2.801- so, let's say the car runs 300lbs/ft @ 3500- well, in 5th, at 3500, you'd multiply 300 by 2.801- you'd be putting down an effective 840lbs/ft. Now, check 1st gear for a reference- 951 has a 3.50, so it's OR is an 11.81, so it would put down over 3500lbs/ft TQ in 1st. This is why shorter gears are faster in a car- when people argue this, you can simply ask "well, is your car faster in 5th than it is in 1st? Think about it...." Anyway, that said, the 968 has a .78 5th, which IS taller than the .83 of the 951, but when combined w/the 3.78 FD of the 968, it becomes an OR of 2.948, which is actually a little SHORTER than the 951 5th (OR).
As for dropping the 951 5th into a 968 box or vice versa, Powerhaus II told me that the gears were NOT interchangeable, although some of the 944, 951, S2, etc, gears are. They also told me that 1st gear was almost impossible to change out in these cars. This is why a R&P swap sounds so good- you could bring each gear up in proportion to each other. If 1st becomes 10% taller, then 6th becomes 10% taller, etc.
Can't answer the TQ-tube question, but there was a guy making aluminum ones here a few years ago that saved ~20lbs IIRC & were really cheap compared to stock. Sounded really cool. The 951 has a ZF LSD- that's a clutch type. They are fine for street & certain types of racing, etc. Many consider the Torsen (TORque SENsing) to be the best, but then, some say the clutch types stabilize the car better, under braking, etc... The Torsen is a type of LSD, just like Posi-traction is, but the Torsen is better known as a torque biassing differential... which one's better really just depends on what type of driving you're doing, personal preference, etc... Danno's Racer X website has a GREAT write-up on all of this if you're intersted- I'll post a link at the bottom again... In most of our cases, though, our factory ZF's have lost a bit of strength & could stand to be rebuilt, etc. I wonder if there's some sort of test one could do to find out...? Anyway, the 968 had BOTH Torsen AND ZF in 1992, but in 1993, they dropped the ZF option, for whatever reason...
WOW, pulling modded Supras....
http://members.rennlist.com/951_racerx/
Just scroll down on the left menu & it's under the heading "Porsche ads, video clips, etc..." you'll find "Gleason- Torsen diff 1" & "Gleason- Torsen Diff 2" - these are the links...
As for dropping the 951 5th into a 968 box or vice versa, Powerhaus II told me that the gears were NOT interchangeable, although some of the 944, 951, S2, etc, gears are. They also told me that 1st gear was almost impossible to change out in these cars. This is why a R&P swap sounds so good- you could bring each gear up in proportion to each other. If 1st becomes 10% taller, then 6th becomes 10% taller, etc.
Can't answer the TQ-tube question, but there was a guy making aluminum ones here a few years ago that saved ~20lbs IIRC & were really cheap compared to stock. Sounded really cool. The 951 has a ZF LSD- that's a clutch type. They are fine for street & certain types of racing, etc. Many consider the Torsen (TORque SENsing) to be the best, but then, some say the clutch types stabilize the car better, under braking, etc... The Torsen is a type of LSD, just like Posi-traction is, but the Torsen is better known as a torque biassing differential... which one's better really just depends on what type of driving you're doing, personal preference, etc... Danno's Racer X website has a GREAT write-up on all of this if you're intersted- I'll post a link at the bottom again... In most of our cases, though, our factory ZF's have lost a bit of strength & could stand to be rebuilt, etc. I wonder if there's some sort of test one could do to find out...? Anyway, the 968 had BOTH Torsen AND ZF in 1992, but in 1993, they dropped the ZF option, for whatever reason...
WOW, pulling modded Supras....
http://members.rennlist.com/951_racerx/
Just scroll down on the left menu & it's under the heading "Porsche ads, video clips, etc..." you'll find "Gleason- Torsen diff 1" & "Gleason- Torsen Diff 2" - these are the links...
11-12-2006, 11:09 PM
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Torque bias versus clutch type LSD... hmmm
Torque bias and clutch style diffs both attempt to transmit power to the axles under all conditions while allowing a degree or percentage of difference in rotational speeds - this is necessary because of the differing radii for each wheel when turning corners. Clutch type diffs have a fixed or set amount of differential that is determined by the clamping force or friction in the internal clutch pack. This also means that the torque applied to both axles will be determined by whatever diff percentage is used to apply lockup under wheelspin & over-run and differential action when turning corners. Torque biasing diffs do not use a set percentage of lockup but employ a patented combination of helical & worm gears (Invex) to deliver equal torque to both axles under all conditions while still allowing differential action when turning. The upside here is that the lockup action under acceleration and over-run is independent from the percentage of the differential action allowed during turns. The bottom line is this - torque bias is more responsive, allows better application of power and is the most consistent/flexible in real word driving conditions. Racing is a different story when you are talking about needing to customize the percentage of lockup for a specific track. Short twisty tracks will favor a larger degree of differential; longer, faster tracks will favor a higher percentage of lockup. Porsche no longer uses Torsen; they offer ZF clutch style and electronically variable diffs for limited slip options. Some may say that clutch style diffs are stronger too. There are numerous applications of both styles out there in the OE world but in terms of raw numbers, Torsen seems to be the favorite. OEM Application list
That's a nutshell description but I hope it helps. Do some more research and talk to the mechanics out there.
Regarding Vegas, you should definitely look up my brother - he's a floor manager at the new Score's over on Procyon. Let me if you plan to go and I'll give him a heads up.
Torque bias and clutch style diffs both attempt to transmit power to the axles under all conditions while allowing a degree or percentage of difference in rotational speeds - this is necessary because of the differing radii for each wheel when turning corners. Clutch type diffs have a fixed or set amount of differential that is determined by the clamping force or friction in the internal clutch pack. This also means that the torque applied to both axles will be determined by whatever diff percentage is used to apply lockup under wheelspin & over-run and differential action when turning corners. Torque biasing diffs do not use a set percentage of lockup but employ a patented combination of helical & worm gears (Invex) to deliver equal torque to both axles under all conditions while still allowing differential action when turning. The upside here is that the lockup action under acceleration and over-run is independent from the percentage of the differential action allowed during turns. The bottom line is this - torque bias is more responsive, allows better application of power and is the most consistent/flexible in real word driving conditions. Racing is a different story when you are talking about needing to customize the percentage of lockup for a specific track. Short twisty tracks will favor a larger degree of differential; longer, faster tracks will favor a higher percentage of lockup. Porsche no longer uses Torsen; they offer ZF clutch style and electronically variable diffs for limited slip options. Some may say that clutch style diffs are stronger too. There are numerous applications of both styles out there in the OE world but in terms of raw numbers, Torsen seems to be the favorite. OEM Application list
That's a nutshell description but I hope it helps. Do some more research and talk to the mechanics out there.
Regarding Vegas, you should definitely look up my brother - he's a floor manager at the new Score's over on Procyon. Let me if you plan to go and I'll give him a heads up.
Last edited by maximus951; 11-13-2006 at 01:36 AM.