Something i have been working on!

[ChasR]

I remember seeing this car in a roadworthy state when I dropped my S2 off to get some work done on it. A week later it was had to believe that much have been stripped off the car!

It looks fanbleedingtastic to be honest! I look forward to going up to EMC (getting the cambelt checked over) to check out your project and to see how it has come on .

Considering I'm relatively local(ish) to both of you, I'd be happy to take a few shots for you of the project (I used to run a photogaphy business with an old friend of mine before I started my new job ).

 

[Neil Haughey]

Wow these maritime blue 944's are breeding.

Great stuff Mark will be fantastic to see that car and something that would be really cool is to see it at some point next to my S2 and/or Lali's 968.

Another bizarre thing it looks like my brother sat down in one of those pictures talking to what looks like Eacock the youngest from behind. I will have to ask Barry about your car, I haven't been to EMC in probably 4 months so seeing this thread is a bolt out of the blue (pardon the pun). I did wonder of you would go to EMC [].

Good luck in Future Classics.

 

[sawood12]

Looks great Mark. Should be a nice toy once you get it up and running. I really like the different approaches various people are taking with their 944 projects. That 1000kg limit looks fairly elusive. I wonder if you could remove the torque tube altogether and have the drive shaft running naked with nothing but a few supporting bearings bolted to the floor pan to prevent whirl. Most other RWD cars have exposed drive shafts and the torque tube must weigh a fair bit.

 

[knightma]

ORIGINAL: sawood12

I wonder if you could remove the torque tube altogether and have the drive shaft running naked with nothing but a few supporting bearings bolted to the floor pan to prevent whirl.  Most other RWD cars have exposed drive shafts and the torque tube must weigh a fair bit.

Scott,

Wouldn't be possible, as the name implies the torque tube carries the torque produced by the engine to the gearbox where it cancels out with the gearbox reaction. This means that the whole engine/torque tube/gearbox assembly imparts no torque around the longitudinal axis into the body of the car (except due to inertia effects) and the mounts have been designed accordingly.

Also, the engine-torque tube-gearbox assembly is only attached to the body of the car with 2 mounts on the engine and 2 on the gearbox. If the engine and gearbox weren't connected via the structural torque tube they would have no support preventing rotation around the transverse axis.

Basically it's not a big strong tube for no reason. Could no doubt be lightened though with more exotic materials and vast cost.

 

[944 man]

As well as the above, it spins at engine speed! Would you really want to drive the car at full chat with DIY propshaft spinning at 7,000rpm? Any weight saving would be cancelled out several times over by all of the sand bags Id want between it an me.....

 

[Neil Haughey]

If you get the chance have a look under a new MX-5, or one of the RX7 (must be same on RX8). Mazda developed a wonderful looking alloy brace that connects the gearbox to the rear axle. Its a work of art and a shame really you have to get under one to see it. I think if Porsche did it again they would do something similar in alloy but probably boxed off to contain the drive shaft and bearings. The torque tube is very very heavy, Barry reckoned it felt as heavy as the gearbox but we didn't weight it to find out. The tube for the torsion bars is also very heavy.

You know how it goes though, if Porsche developed a new 944 it would probably have 50+ kg saved from those components and another 20 or 30 Kg from using plastic panels all of which would go back in to make the cabin larger and stronger to pass crash tests and provide a suitably stiff platform.

 

[sawood12]

It must be possible. Its the drive shaft that runs inside the torque tube that transmits the torque and turns. I had always supposed it was quite sturdy to prevent the long, slender driveshaft from whirling outwards - basically providing the means to be able to support the drive shaft with a couple or few bearings along its length. No other solution is possible for a road without having some form of major structure in the floorpan - which is difficult, but if you are stripping a shell and installing a roll cage then you could very easily incorporate some form of support hanging off the roll cage that some bearing carriers could be attached by bolts through the floorpan into the added structure to support the drive shaft. I hadn't appreciated that the gearbox is also supported by the torque tube, but that is easlily remedied by a similar solution. The torque tube can't carry any torque as it is bolted to the gearbox casing at one end and the engine at the other - it doesn't rotate - it is simply a support for the bearings and needs to be heavy and strong due to its length. The only other areas that might need some attention would be where the drive shaft slots into the engine at one end and the gearbox at the other - some form of seal might need incorporating to prevent water from getting into the gearbox and engine through the drive shaft splines (or oil getting out).

Just a thought. The fact that it hasn't been done before doesn't necessarily mean it can't be done. I wonder if other transaxel cars have a similar torque tube arrangement.

 

[knightma]

ORIGINAL: sawood12

The torque tube can't carry any torque as it is bolted to the gearbox casing at one end and the engine at the other  - it doesn't rotate - it is simply a support for the bearings and needs to be heavy and strong due to its length.

Sorry Scott but this is totally wrong. The torque tube does carry torque, the clue is in the name is it not? A tube can transmit a torque without rotating. It transmits the equal but opposite torque to what the drive shaft transmits meaning neither the engine or gearbox tries to twist within the body of the car. Newton's third law of motion states "to every action there is an equal and opposite reaction." Without the torque tube connecting the engine to the gearbox, both the engine mounts and gearbox mounts would have to carry this torque. Both would still cancel out but the load path would be through the body of the car and the mounts. As I said the mounts have not been designed for this.

Also as I said, mounting the engine on just 2 mounts in isolation is not stable. If you've ever changed the clutch you will know what I mean. The engine just rocks backwards and forwards without the torque tube connected. The same applies to the gearbox with the 2 gearbox mounts. However when they are joined by the torque tube the whole assembly is perfectly stable on the 4 mounts.

 

[944Turbo]

Many new sportscars are adopting the torque tube - Ferraris and masers, lexus LFA, skyline etc.

The torque tube stops the gearbox rotating upwards when you accelerate putting all the weight of the engine as a big pendulum on the front, there are also some benefits in opposing the twisting torque of the engine along the axis of the car.

Tony

 

[DivineE]

Don't they also have a function in the crash protection role in a 944. I think someone one said they were designed so that in a front impact situation, the energy is transmitted through the car and into the spare wheel rather than the engine coming into the footwell. Food for thought or discussion at least

 

[DivineE]

ORIGINAL: ChasR

I look forward to going up to EMC (getting the cambelt checked over) to check out your project and to see how it has come on .

Just to mention if you do get it done make sure you change the rollers and tensioners also. My friend bought an S2 that had had the main drive belts changed (by EMC actually) 2000miles later the water pump was thought to be failed so he took the covers off to do the job and found that the rolers were original, one had seised from rust and it was a BIG mess! I have a picture somewhere of the result!! Always worth changing them for the small cost. ESPECIALLY on a cambelt

 

[zcacogp]

ORIGINAL: 944Turbo

The torque tube stops the gearbox rotating upwards when you accelerate putting all the weight of the engine as a big pendulum on the front, there are also some benefits in opposing the twisting torque of the engine along the axis of the car.

As I understand it, that's the major job of the torque tube - preventing torsional force associated with the drive from being transmitted to the bodyshell from either the gearbox or the engine. (OK, there will be some, but it will be massively reduced.) Effectively, it bolts the engine and the gearbox together into a single assembly, so the only forces on it (as an assembly) are those external to it, associated with the drive to the driveshafts and wheels.

Having said that, Scott's suggestion is not that mad. There must be a lighter way of achieving the same thing - perhaps, as Neil suggested, by using some form of lightweight alloy bracket between the two, along the length of the car, to ensure that all torque associated with the drive from engine to gearbox is kept within the assembly. It would need to be carefully designed, and would need to carry the bearings to prevent the prop shaft (internal drive shaft) from 'whipping', but may not be beyond the realms of possibility. Would be VERY expensive tho' ...


Oli.

 

[MarkK]

My next steps to making the car lighter (if it needs it,and when budget allows) are a Lexan hatch maybe and some non pop up head lights,much easier..,hopefully seeing the car painted on friday so should have some more pics.

 

[Hilux]

Sorry Scott but this is totally wrong. The torque tube does carry torque, the clue is in the name is it not? A tube can transmit a torque without rotating. It transmits the equal but opposite torque to what the drive shaft transmits meaning neither the engine or gearbox tries to twist within the body of the car. Newton's third law of motion states "to every action there is an equal and opposite reaction." Without the torque tube connecting the engine to the gearbox, both the engine mounts and gearbox mounts would have to carry this torque. Both would still cancel out but the load path would be through the body of the car and the mounts. As I said the mounts have not been designed for this.

Also as I said, mounting the engine on just 2 mounts in isolation is not stable. If you've ever changed the clutch you will know what I mean. The engine just rocks backwards and forwards without the torque tube connected. The same applies to the gearbox with the 2 gearbox mounts. However when they are joined by the torque tube the whole assembly is perfectly stable on the 4 mounts.

The engine imparts torque to the gearbox via the tube so it does carry it however its function is to resist torque. The gearbox offers resistance to the moment via the road wheels thereby the engine will want to rotate. It cannot because it is bolted to the car. Same applies to the gearbox. It is also bolted to the car and steadied with connection to the road wheels.

The torque tube imparts the engine torque to the gearbox in two ways 1) in a casing strong enough to resist flexing and brace and align the driveshaft and also to resist torsion [hence its weight due the gauge of steel required to do this] and 2) to tie the engine and gearbox together so they impart torque to the wheels. Remove the engine and gearbox mounts and the wheels will stand still and the engine and gearbox will rotate.

 

[sawood12]

I can imagine exactly what is going on - the torque tube connects the engine and gearbox, as the engine tries to rotate relative to the gearbox the torque tube prevents this relative motion. The reason this relative motion needs to be prevented is that the driveshaft is not connected at either end by Universal Joints as normal rear wheel drive cars are, which accommodates any relative movement of the engine and the diff. This means there cannot be any relative motion between the engine and gearbox or the driveshaft will be put under a bending force and that will cause the driveshaft to whirl out like a skipping rope, thus imparting huge stresses onto it and shearing it. Universal Joints cannot be used due to the higher RPM and higher torque being transmitted by the drive shaft meaning that any out of balance needs to be very tightly controlled. That is why it is called a Torque Tube.

However if you can tie the gearbox and the engine firm such that it only rotates around the axis of the drive shaft (e.g. solid mounts on the engine and gearbox) then there is no reason why the torque tube is needed. Having said that I wasn't aware of the mount arrangements on the engine i.e. that the torque tube is also preventing the relative lateral movement of the engine and gearbox, so that pretty much scuppers my bright idea - or at least makes any solution not worth it. Oh well, back to the drawing board.

 

[Neil Haughey]

Very true, Porsche simplified the design as much as possible. Its very neat but to me a huge metal tube is not exactly high tech is it.

 

[ChasR]

ORIGINAL: DivineE

ORIGINAL: ChasR

I look forward to going up to EMC (getting the cambelt checked over) to check out your project and to see how it has come on .

Just to mention if you do get it done make sure you change the rollers and tensioners also. My friend bought an S2 that had had the main drive belts changed (by EMC actually) 2000miles later the water pump was thought to be failed so he took the covers off to do the job and found that the rolers were original, one had seised from rust and it was a BIG mess! I have a picture somewhere of the result!! Always worth changing them for the small cost. ESPECIALLY on a cambelt

When I went to EMC he recommended me to change the rollers and tensioners. As a result there were 2 belts, and 5 tensioners on the passenger seat when I dropped the engine and car off to them . It's going back to get the belt tension checked since I have done around 1500 miles on the new engine.

 

[MarkK]

Its Primered![]

 

[MarkK]

And one more..Should be all blue next week...excited, you can see the hole for the badge has been filled,a lightweight sticker version will make it much quicker[]

 

[sawood12]

ORIGINAL: MarkK

And one more..Should be all blue next week...excited, you can see the hole for the badge has been filled,a lightweight sticker version will make it much quicker[]

Are you sure that filler plus sticker isn't just as heavy as a proper badge!