Rotary Ressurection Updates
08-07-2003, 10:39 PM
#13
Senior Member
Thread Starter
Join Date: Feb 2002
Posts: 173
Here is some info enjoy.
Lately, we've had the opportunity to showcase several different types of transaxles built For sand cars here in Sand Sports tm magazine. Our goal is to feature the different options that are available, and leave it up to perspective car builders and owners to make the decision which drive train system is best suited for their needs. For this issue, we'll be taking a look at the Porsche 930 transaxle, which is a super strong 4-speed gear box that definitely is a viable option for use in hi-performance sand cars. It is currently available through Mechtech Motorsports, located in Escondido, CA, and recently we had the opportunity to visit with shop owner, Jim McFarland, to learn a little more about the technicals of this trans, and shoot some detailed pictures for readers that are interested in a new transaxle option.
In speaking with Jim McFarland, he told us that the reason why the Porsche 930 gear box was chosen is that it is the strongest model that Porsche has built. Also, being a 4-speed transaxle, it is better suited for sand and off-road cars because most recreational cars do not need more than four forward gears. For the most part, 5-speed transaxles are generally intended for street use where fuel economy is a factor in overall performance. The 930 transaxle is also about 35% stronger than any other transaxle that Porsche built for their production cars. McFarland also added that he believes the Porsche factory torque ratings for the 930 trans is rated at well over 500 ft.-lbs. of torque and about 500hp in stock condition. Keep in mind that this trans was used in the Porsche 930 turbo and 911 vehicles between the years of 1978 and 1989, which is when Porsche began using a 5-speed trans. So needless to say, quite a few of these transaxles were produced by the factory and sold here in the U.S., and it's fairly easy to locate them for custom built off-road
Here's an overall view of the Porsche 930 gear box, which was used in the 911 vehicles between the years of 1978 and 1989. The trans weighs about 150 lbs., measures b-in. wide, 27-1/2-in. long, and it has a strong 12-bolt 9-1/2-in. dia. ring and pinion design.
Aside from the stout construction, another good feature of this gear box is the strong internal components. The ring and pinion section is ever bit as strong of the other hybrid transaxles on the market today, not to mention the physical characteristics of the drive gears. Compare the width of the Porsche gear with that of the late model Type 2 VW gears, such as the 091 versions, and you'll see that the Porsche gears are nearly twice as wide. This means the gears are much stronger during engagement, and they also have a better synchro design than VW transaxles and aftermarket transaxles that use VW-style gears. Other features of the 930 trans are the size of the synchro hubs, and the way that the gears are splined onto the main shaft, as opposed to being machined from a one-piece bar stock such as the VW design. It's also important to note that gear strength is very important but there have been instances where, if the gears don't break in a VW transaxle, oftentimes the synchro, hubs will actually twist or split into two pieces. Porsche was able to find a cure for this weak link.
Check out these photos showing the super tough gear stack and ring gear. As you can see, the tooth depth on the Porsche 930 ring gear is twice the depth of a Type 2 VW, and the gears are massive. Reverse side of the ring gear shows the 12-bolt layout.
FAR LEFT, comparison of three different ring gears, just to give you an idea of how large the stock Porsche gear sizes up. Porsche 930 ring gear is on the far left, Type 2 VW in the center and Type 1 VW at right. Also note how large the bearings are in this trans.
Almost anyone who has run a Type 2 VW trans with extreme horsepower has probably experienced some sort of failure associated with the gears and/or synchros. This is what prompted McFarland to begin looking for an alternative type of transaxle. For him, the answer came in the form of this Porsche 930 trans. Two of the most positive design features were that the gears are splined onto to main shaft, and the synchros design than VW transaxles and aftermarket transaxles that use VW-style gears. Other features of the 930 trans are the size of the synchro hubs, and the way that the gears are splined onto the main shaft, as opposed to being machined from a one-piece bar stock such as the VW design. It's also important to note that gear strength is very important but there have been instances where, if the gears don't break in a VW transaxle, oftentimes the synchro, hubs will actually twist or split into two pieces. Porsche was able to find a cure for this weak link.
Almost anyone who has run a Type 2 VW trans with extreme horsepower has probably experienced some sort of failure associated with the gears and/or synchros. This is what prompted McFarland to begin looking for an alternative type of transaxle. For him, the answer came in the form of this Porsche 930 trans. Two of the most positive design features were that the gears are splined onto to main shaft, and the synchros are very large and made from high quality steel. Also, when you look at the synchronizers you'll see that they synchronize in two places - internally and externally. What actually happens here is that when the slider forces onto the synchronizer it causes the synchro hub to brake on the interior and exterior simultaneously. For this reason, you could actually consider this to be a dual synchronizer. Another design feature of the 930 trans that adds to the overall strength is that none of the gears are fixed on the pinion shaft. Likewise, since none of the gears are integrated onto the main shaft, should a gear failure ever occur, you don't have to replace the entire shaft.
LEFT, this is the Porsche pinion bearing retainer plate. The plate at right is a stock unit, which is adequate for normal use, however, a beefier chrome moly unit (left) is available.
One of the features of this trans that makes it extra strong is the main shaft design. Instead of machining the gears on the shaft itself, as a VW (shown above), the gears are splined.
This is a Photo of the Porsche 930 input staff. The gear shown in the above picture is splined on this shaft, which makes for a very strong transaxle drive system. Not only did Porsche engineers use quality materials, their parts were designed for lots of hp.
Here's an example of the difference in width between a Type 2 VW gear (left), and the Porsche 930 gear, at right.
This is a view of the synchronizer that's used in the Porsche gear box. They actually synchronize on the gear in two areas.
This is only a small sampling of the gear selection available for this trans. In all, there are about 120 different ratios.
There are several ring and pinion options available for this trans. Some of the ratios are stock Porsche parts, and others are aftermarket units made by private manufacturers. The most popular stock ratio in this particular gear box is a 4.22:1 ratio. Mechtech also offers ratios such as 4.62, 4.87, 5.12, and they have a 4.0: 1, which is obviously something that you would not want for use in a sand car. In most cases, with the 4.22:1 ring and pinion very strong part in stock form, coupled with an unlimited amount of gear ratios to choose from, this is optimum for most sand car applications. The aftermarket gears are made here in America, and there are about 120 different gear combinations to choose from between first and fourth. Basically, it's possible to obtain any ratio that a car owner needs.
Another aspect about this trans that makes it more practical is that all the gears are totally usable. Often you will see that car owners with a Type 2 VW gear box rarely use the first gear, aside from loading the car back onto the trailer. This would be with the typical ratio of 3.70 or 3.50 1 st gear ratio. With the Porsche 930, they can supply you with a 2.25:1 first gear, which is a little lower than what would normally be used in a VW for second gear, but it's still taller than a common VW I st gear. That combination ends up working out pretty good for high torque, large displacement engines such as a V6- or a V8 powered buggy. These engines can easily pull a taller first gear.However, if it were a smaller displacement VW engine, or a Rotary, you may want to lower that gear ratio slightly.
Generally, what Mechtech has been doing up to this point is leaving the ring and pinion ratio stock and then selecting the best first through fourth gear ratio stack to suit the demands of the engine's torque and powerband. The reason why some of the gear ratios need to be changed is that the stock trans was designed for a Porsche 911 that was capable of running well over 150mph. Mechtech is simply re-gearing the trans so that the car owner can effectively use all the gears. And in the end they can supply the customer with a usable 4th gear that can also double as an overdrive gear. In this case, even though you wouldn't necessarily dune in 4th gear, you can still use that gear when cruising through the flats, across sand highway, as well as other terrain such as hard-packed desert off-road recreation areas.
Here's a look at the stock differential and spider gears. In stock differential and spider gears. In stock form there are two very large spiders, designed fo 500hp.
If you think that you need more internal strength, there's an optional chrome moly diff that houses four spider gears
This is the center section of the gear box. We included it to show you the gear selector design of the porsche 930 trans.
There is an optinal heavy duty side cover available, but looking at the stock cover you can see it's very stout.
Here's a look at the Porsche 930 slider ring and shift fork. You can see the shift fork was designed for added strength.
This is a closer view of the slider ring, and the slider hub. Here you can see the massive splines and size of the shift hub.
Retrofitting this Porsche box into a car that currently uses a VW-style trans, or a gear box with a bellhousing that has a VW bolt pattern, would be fairly simple. The same engine adapter that they are currently using (if applicable) would bolt right up. All you would need to do is buy a new clutch and flywheel, and fabricate new brackets to mount the trans in the frame. The reason for this is the front pad mount is completely different than other transaxles, and the shifter shaft is in a completely different location. Actually, these are two really good features of the Porsche 930 transaxle. Not only does it have a super strong and sturdy mounting design, it also has a precision shifter which operates very smooth. We should also note that there are three different stages of clutches available for this trans, which are rated in terms of engine horsepower. The interesting feature about these clutches, as compared to traditional VW-style clutches, is that this is a puller-type clutch. You'll find these clutches on most of the new high horsepower cars built today, such as the Corvette, Toyota Supra, and many other performance automobiles. And the reason for this puller configuration is that it provides for a much stronger design without having excessive pedal travel and pressure.
While we understand that people are generally not experiencing problems with ring and pinion failures, or breaking the cases of most aftermarket hybrid transaxles, the units that are equipped with VW gears can potentially have a weak link that needs to be addressed. That's where Jim McFarland feels that the Porsche 930 Powerhouse trans fills a void for certain applications. Even with the upgraded aftermarket gears, this transmission is still less expensive than many of the aftermarket units being built today. The availability is good, there are a wide variety of gears ratios to choose, lubrication properties are excellent, the bearings are much larger than what you'll find in most gear boxes, and the synchros are a whole lot stronger than those in other transaxles
Lately, we've had the opportunity to showcase several different types of transaxles built For sand cars here in Sand Sports tm magazine. Our goal is to feature the different options that are available, and leave it up to perspective car builders and owners to make the decision which drive train system is best suited for their needs. For this issue, we'll be taking a look at the Porsche 930 transaxle, which is a super strong 4-speed gear box that definitely is a viable option for use in hi-performance sand cars. It is currently available through Mechtech Motorsports, located in Escondido, CA, and recently we had the opportunity to visit with shop owner, Jim McFarland, to learn a little more about the technicals of this trans, and shoot some detailed pictures for readers that are interested in a new transaxle option.
In speaking with Jim McFarland, he told us that the reason why the Porsche 930 gear box was chosen is that it is the strongest model that Porsche has built. Also, being a 4-speed transaxle, it is better suited for sand and off-road cars because most recreational cars do not need more than four forward gears. For the most part, 5-speed transaxles are generally intended for street use where fuel economy is a factor in overall performance. The 930 transaxle is also about 35% stronger than any other transaxle that Porsche built for their production cars. McFarland also added that he believes the Porsche factory torque ratings for the 930 trans is rated at well over 500 ft.-lbs. of torque and about 500hp in stock condition. Keep in mind that this trans was used in the Porsche 930 turbo and 911 vehicles between the years of 1978 and 1989, which is when Porsche began using a 5-speed trans. So needless to say, quite a few of these transaxles were produced by the factory and sold here in the U.S., and it's fairly easy to locate them for custom built off-road
Here's an overall view of the Porsche 930 gear box, which was used in the 911 vehicles between the years of 1978 and 1989. The trans weighs about 150 lbs., measures b-in. wide, 27-1/2-in. long, and it has a strong 12-bolt 9-1/2-in. dia. ring and pinion design.
Aside from the stout construction, another good feature of this gear box is the strong internal components. The ring and pinion section is ever bit as strong of the other hybrid transaxles on the market today, not to mention the physical characteristics of the drive gears. Compare the width of the Porsche gear with that of the late model Type 2 VW gears, such as the 091 versions, and you'll see that the Porsche gears are nearly twice as wide. This means the gears are much stronger during engagement, and they also have a better synchro design than VW transaxles and aftermarket transaxles that use VW-style gears. Other features of the 930 trans are the size of the synchro hubs, and the way that the gears are splined onto the main shaft, as opposed to being machined from a one-piece bar stock such as the VW design. It's also important to note that gear strength is very important but there have been instances where, if the gears don't break in a VW transaxle, oftentimes the synchro, hubs will actually twist or split into two pieces. Porsche was able to find a cure for this weak link.
Check out these photos showing the super tough gear stack and ring gear. As you can see, the tooth depth on the Porsche 930 ring gear is twice the depth of a Type 2 VW, and the gears are massive. Reverse side of the ring gear shows the 12-bolt layout.
FAR LEFT, comparison of three different ring gears, just to give you an idea of how large the stock Porsche gear sizes up. Porsche 930 ring gear is on the far left, Type 2 VW in the center and Type 1 VW at right. Also note how large the bearings are in this trans.
Almost anyone who has run a Type 2 VW trans with extreme horsepower has probably experienced some sort of failure associated with the gears and/or synchros. This is what prompted McFarland to begin looking for an alternative type of transaxle. For him, the answer came in the form of this Porsche 930 trans. Two of the most positive design features were that the gears are splined onto to main shaft, and the synchros design than VW transaxles and aftermarket transaxles that use VW-style gears. Other features of the 930 trans are the size of the synchro hubs, and the way that the gears are splined onto the main shaft, as opposed to being machined from a one-piece bar stock such as the VW design. It's also important to note that gear strength is very important but there have been instances where, if the gears don't break in a VW transaxle, oftentimes the synchro, hubs will actually twist or split into two pieces. Porsche was able to find a cure for this weak link.
Almost anyone who has run a Type 2 VW trans with extreme horsepower has probably experienced some sort of failure associated with the gears and/or synchros. This is what prompted McFarland to begin looking for an alternative type of transaxle. For him, the answer came in the form of this Porsche 930 trans. Two of the most positive design features were that the gears are splined onto to main shaft, and the synchros are very large and made from high quality steel. Also, when you look at the synchronizers you'll see that they synchronize in two places - internally and externally. What actually happens here is that when the slider forces onto the synchronizer it causes the synchro hub to brake on the interior and exterior simultaneously. For this reason, you could actually consider this to be a dual synchronizer. Another design feature of the 930 trans that adds to the overall strength is that none of the gears are fixed on the pinion shaft. Likewise, since none of the gears are integrated onto the main shaft, should a gear failure ever occur, you don't have to replace the entire shaft.
LEFT, this is the Porsche pinion bearing retainer plate. The plate at right is a stock unit, which is adequate for normal use, however, a beefier chrome moly unit (left) is available.
One of the features of this trans that makes it extra strong is the main shaft design. Instead of machining the gears on the shaft itself, as a VW (shown above), the gears are splined.
This is a Photo of the Porsche 930 input staff. The gear shown in the above picture is splined on this shaft, which makes for a very strong transaxle drive system. Not only did Porsche engineers use quality materials, their parts were designed for lots of hp.
Here's an example of the difference in width between a Type 2 VW gear (left), and the Porsche 930 gear, at right.
This is a view of the synchronizer that's used in the Porsche gear box. They actually synchronize on the gear in two areas.
This is only a small sampling of the gear selection available for this trans. In all, there are about 120 different ratios.
There are several ring and pinion options available for this trans. Some of the ratios are stock Porsche parts, and others are aftermarket units made by private manufacturers. The most popular stock ratio in this particular gear box is a 4.22:1 ratio. Mechtech also offers ratios such as 4.62, 4.87, 5.12, and they have a 4.0: 1, which is obviously something that you would not want for use in a sand car. In most cases, with the 4.22:1 ring and pinion very strong part in stock form, coupled with an unlimited amount of gear ratios to choose from, this is optimum for most sand car applications. The aftermarket gears are made here in America, and there are about 120 different gear combinations to choose from between first and fourth. Basically, it's possible to obtain any ratio that a car owner needs.
Another aspect about this trans that makes it more practical is that all the gears are totally usable. Often you will see that car owners with a Type 2 VW gear box rarely use the first gear, aside from loading the car back onto the trailer. This would be with the typical ratio of 3.70 or 3.50 1 st gear ratio. With the Porsche 930, they can supply you with a 2.25:1 first gear, which is a little lower than what would normally be used in a VW for second gear, but it's still taller than a common VW I st gear. That combination ends up working out pretty good for high torque, large displacement engines such as a V6- or a V8 powered buggy. These engines can easily pull a taller first gear.However, if it were a smaller displacement VW engine, or a Rotary, you may want to lower that gear ratio slightly.
Generally, what Mechtech has been doing up to this point is leaving the ring and pinion ratio stock and then selecting the best first through fourth gear ratio stack to suit the demands of the engine's torque and powerband. The reason why some of the gear ratios need to be changed is that the stock trans was designed for a Porsche 911 that was capable of running well over 150mph. Mechtech is simply re-gearing the trans so that the car owner can effectively use all the gears. And in the end they can supply the customer with a usable 4th gear that can also double as an overdrive gear. In this case, even though you wouldn't necessarily dune in 4th gear, you can still use that gear when cruising through the flats, across sand highway, as well as other terrain such as hard-packed desert off-road recreation areas.
Here's a look at the stock differential and spider gears. In stock differential and spider gears. In stock form there are two very large spiders, designed fo 500hp.
If you think that you need more internal strength, there's an optional chrome moly diff that houses four spider gears
This is the center section of the gear box. We included it to show you the gear selector design of the porsche 930 trans.
There is an optinal heavy duty side cover available, but looking at the stock cover you can see it's very stout.
Here's a look at the Porsche 930 slider ring and shift fork. You can see the shift fork was designed for added strength.
This is a closer view of the slider ring, and the slider hub. Here you can see the massive splines and size of the shift hub.
Retrofitting this Porsche box into a car that currently uses a VW-style trans, or a gear box with a bellhousing that has a VW bolt pattern, would be fairly simple. The same engine adapter that they are currently using (if applicable) would bolt right up. All you would need to do is buy a new clutch and flywheel, and fabricate new brackets to mount the trans in the frame. The reason for this is the front pad mount is completely different than other transaxles, and the shifter shaft is in a completely different location. Actually, these are two really good features of the Porsche 930 transaxle. Not only does it have a super strong and sturdy mounting design, it also has a precision shifter which operates very smooth. We should also note that there are three different stages of clutches available for this trans, which are rated in terms of engine horsepower. The interesting feature about these clutches, as compared to traditional VW-style clutches, is that this is a puller-type clutch. You'll find these clutches on most of the new high horsepower cars built today, such as the Corvette, Toyota Supra, and many other performance automobiles. And the reason for this puller configuration is that it provides for a much stronger design without having excessive pedal travel and pressure.
While we understand that people are generally not experiencing problems with ring and pinion failures, or breaking the cases of most aftermarket hybrid transaxles, the units that are equipped with VW gears can potentially have a weak link that needs to be addressed. That's where Jim McFarland feels that the Porsche 930 Powerhouse trans fills a void for certain applications. Even with the upgraded aftermarket gears, this transmission is still less expensive than many of the aftermarket units being built today. The availability is good, there are a wide variety of gears ratios to choose, lubrication properties are excellent, the bearings are much larger than what you'll find in most gear boxes, and the synchros are a whole lot stronger than those in other transaxles
i'm really interested in your progress keep updating us.
08-11-2003, 03:44 PM
#16
Senior Member
Thread Starter
Join Date: Feb 2002
Posts: 173
No i can. I'm just playing. See my bike just got stolen, so now i have a payment on something that is gone.
I figure I just someone else's money b4 mine.hahah.im a bastard.im kidding though.
I guess i can post some stripped down pics.I have also decided on plum for a body color.why?no one will have this design. plus it looks good with carbon fiber.also seeing all accessories and turbo pieces come in purple.
greddy bov
turbonetics insignia
ground straps
and more i just can't think
I figure I just someone else's money b4 mine.hahah.im a bastard.im kidding though.
I guess i can post some stripped down pics.I have also decided on plum for a body color.why?no one will have this design. plus it looks good with carbon fiber.also seeing all accessories and turbo pieces come in purple.
greddy bov
turbonetics insignia
ground straps
and more i just can't think
08-11-2003, 04:27 PM
#17
Senior Member
Thread Starter
Join Date: Feb 2002
Posts: 173
Sorry for me putting this list here taking up bandwith.
Not an update just a list of everything i need to buy for the front end of my project.i have nowhere else to keep i.
15gal fuel cell
locking gas cap
radiator shroud
stock front diffuser
brembo cross drilled rotors
scoot hood
RE lights
aquamist
brake pads
powdercoated calipers
brake proportioning valve
carpeting
aeromotive fuel pump
fuel lines
radiator lines
sheet metal sheet metal
Not an update just a list of everything i need to buy for the front end of my project.i have nowhere else to keep i.
15gal fuel cell
locking gas cap
radiator shroud
stock front diffuser
brembo cross drilled rotors
scoot hood
RE lights
aquamist
brake pads
powdercoated calipers
brake proportioning valve
carpeting
aeromotive fuel pump
fuel lines
radiator lines
sheet metal sheet metal
08-11-2003, 04:52 PM
#19
Senior Member
Join Date: Jan 2002
Location: Birmingham, AL
Posts: 844
You could type it in notepad and save it in your computer.
Got a couple questions for you
What ecu are you going to use? What subframe? What exhaust manifold? What wire harness? Do you want a/c and powersteering? If so how will you adapt them? What trans will work with a 12a end housing?
STEPHEN
Got a couple questions for you
What ecu are you going to use? What subframe? What exhaust manifold? What wire harness? Do you want a/c and powersteering? If so how will you adapt them? What trans will work with a 12a end housing?
STEPHEN