TheSamba.com :: View topic - New (probably stupid) AWD drivetrain idea

Sun Dec 04, 2016 2:35 pm

Hi, I have an idea, which will probably not work, because I'm a total amateur... So sorry in advance :)

I've been reading topics here about the flipped quattro gearbox, reverse running engines with quattro drivetrain, and the subaru drivetrain.

As I see, I'm not the only one, who would like to use a stronger drivetrain, instead of the stock syncro. But I'd like to keep the granny gear (or something similar) for offroading, which is a problem:
- the subaru drivetrain is great, but there is no dual range gearbox yet,
- the reverse running engine, with quattro drivetrain may have low range, but the reverse running engine seems too complicated to me,
- the flipped audi gearbox is simple and cheap, but will not work with low range allroad quattro gearbox, because of it's length. I think the whole engine and gearbox should be lowered a lot, much more, than a 2wd.

The gearing of a low range allroad gearbox seems ideal for me, as the low range 1st gear is only a little bit longer than the stock G-gear, so in low range, it's ideal for off roading, and in normal range it's good for highways

So, my idea is to use any engine (I prefer tdi, but that's not important), and use an allroad quattro low range drivetrain, but not flipped. To rotate the wheels the right direction, I need to put a reverser somewhere between the engine, and the gearbox (I don't know, which is better, between the engine and flywheel - this is on my drawing - , or between the clutch and the gearbox)

This reverser is like a portal axle in a case, which case is also an adaptor plate between the engine and the bellhousing. So it's a custom made case which has housing for the gears (I guess they need some bearings) with the input from the engine, and output to the gearbox.

The box will have a width, which means, the gearbox will move forward a few inches. This is a problem to solve, and I don't know the answer. The output shaft is also a few inches downwards from the input shaft, so the gearbox is low mounted, and it affects ground clearence. I think, some inches of clearence can be achieved by lifting the whole van.

I don't know, how to make the box, or which gears, bearings, shafts and flanges to be used, but it' just an idea...

What do you guys think? Is it worth the thinking?

Here is a quick and lame drawing of the drivetrain:

Sun Dec 04, 2016 2:43 pm

you could also theorize a 1:1 reverser built to replace the trailing arms.
sorta like the old VW reduction gear boxes but one that pivots to incorporate the suspension and allows a 1:1 ratio.

Sun Dec 04, 2016 3:35 pm

danfromsyr wrote: you could also theorize a 1:1 reverser built to replace the trailing arms.
sorta like the old VW reduction gear boxes but one that pivots to incorporate the suspension and allows a 1:1 ratio.

Doesn't need to be 1:1, it can be whatever ratio is desired. A little increase in ground clearance would be nice too. Would be difficult to package all that monkeybusiness with the front steering etc. It can't fit inside the dish of the wheel. Can the front syncro diff be flipped/reversed?

Sun Dec 04, 2016 3:44 pm

Portals would be the hot trick

Sun Dec 04, 2016 10:57 pm

Hey Krumel:

I like your idea. There are some limitations, however. Here in North America, there were either no manual transmission AllRoad cars or very few of them - - they were all automatic transaxles with clever but complicated electronic controls and sensors. In Europe also, there were very few manual Allroad transaxles. That leaves availability low and prices high.

There were several years of the manual boxes which included a low range. All of this is good. The difficulty is in reversing rotation. Very few engines would run properly without the flywheel attached directly to the crankshaft, so the reversing box would have to be located elsewhere. It would be possible to fabricate and install a reversing gearset in the space occupied by the center differential and leave the centre diff out. This would then rotate the inner shaft inside the countershaft (the one that drives the pinion) in the opposite direction from the outer shaft in which it rotates. This speed difference between the two shafts would be very high and even though they roll on tapered cageless roller bearings, they would likely need pressure gear oil lubrication to overcome the heat generated by these fast-rotating bearings. In the factory configuration, the speed differences between the inner and out shafts are due only to the action of the centre differential - - in other words, the speed difference is the speed difference between the speed of the front wheels compared to the rear wheels when rounding a sharp turn or when one or more wheels have lost traction and are spinning.

Note that the 6th gear ratio is approximately 0.55 in these 01E gearboxes (maybe 0.65 or 0.70 for the Allroad, can't recall exactly). This means, for example, that at 2,500 rpm engine speed, the outer shaft is turning at 2,500/0.65 = 3850 rpm, while the inner pinion shaft in a reversed transaxle would be rotating at 3,850 rpm in the opposite direction. This is essentially equal to a shaft spinning in its bearings at 7,700 rpm when you are highway cruising, which is a lot for a transmission shaft and the bearings in which it turns. These are the reasons I thought that the 01E, which is a great, strong, transaxle, might not work in this configuration.

If we could persuade the folks at Subarugears to make a reversed ring and pinion set for the Audi 01E, (assuming it is even possible), we would have a great transaxle option for the Syncro.

Mon Dec 05, 2016 12:28 am

Thanks for the replies!

danfromsyr, Sodo:
I think, in the rear, the reverser portals are a good idea, and if it's 1:1 then the front diff can be flipped, so it's only two reversers to be fabricated. It seems like a good idea, but I don't know if it would be more expensive (make two magic boxes instead of one). But is someone would make a few of it, I think there would be a market for it. I couldn't find 2 gears reversing bolt on portals, only 4 gears non-reversing type (and that's 5000$ per piece...)

I also have an idea of putting the 2 reversers in two boxes, which are located in a frame around the gearbox. The frame is also the mounting of the gearbox, so the reverser boxes are fixed to the gearbox. The rear flanges go directly to the input of the boxes on both sides, and the output of the boxes are attached to shortened half shafts. In this case, there is no need to modify the trailing arm, but no gain of portal height.

Howesight:
Ok, forget the low range for a moment. If the reverser is not 1:1, but about 1:3, the gearing would be a compromise without the low range (rpm with 235/75r15 wheels):
Stock G: 6.03 x 4.86 = 29.3
Stock 4: 0.85 x 4.86 = 4.1 (rpm 3042 at 100 km/h )
Audi 1: 3.75 x 4.38 x 1.3 = 21.4
Audi 6: 0.60 x 4.38 x 1.3 = 3.4 (rpm 2515 at 100 km/h)

So, without the low range, but with an 1:3 reverser, it seems usable for me. It's not that good for offroad, like the stock G, or low range, but better than a stock 01E gearbox 1st. And highway rpm is almost the same, like stock syncro gearbox, with 0.7 4th (that is 2505 at 100 km/h). It looks like it's too much thinking for nothing, but if the reverser is correctly made, that's the only custom part. The non-low range 01E gearboxes are widely available and strong, while stock syncro boxes are rare and weak.

Returning to the low range now. As I saw in other topics, you've had an idea to reverse the rotation inside the gearbox. This is way beyond my knowledge :) If you figure it out, I will be more than happy, but I don't have any idea of it, because I'e only once seen a gearbox inside (when the mechanic repaired my syncro gearbox). So that's why I'm thinking of custom things only outside the gearbox. And if the gearbox fails, it' can be easily repaced without modification.

As other location: what if the reverser box is located between the clutch, and the gearbox? I can't really imagine the adaptor plate/case's shape, it'll surely need some cad design. And it also needs a custom made clutch lever. But with all these, is it doable? In this case, flywheel is on the crankshaft.

Mon Dec 05, 2016 3:41 am

krumelmonster wrote:
As other location: what if the reverser box is located between the clutch, and the gearbox? I can't really imagine the adaptor plate/case's shape, it'll surely need some cad design. And it also needs a custom made clutch lever. But with all these, is it doable? In this case, flywheel is on the crankshaft.

I Think this is the better setup. The reverser box should contain the clutch and its parts on the flywheel side while the output is like a fake clutch that the gearbox input shaft can slide into. With a
Would be much easier to do it on a gearbox like the Vanagon's original or Renault UN1 where the bellhousing can be removed. Then you can install the magic box between the bellhousing and the gearbox.
Or the magic box could slide into the bellhousing of the gearbox.

But I think it would cost less to design/manufacture reversed ring/pinion sets like Subarugears did.

Mon Dec 05, 2016 9:55 am

Nice drawing ZsZ :)

I don't know if the magic box can slide into the bellhousing, quite complex design is needed for that, I guess...

Surely, a reversed ring/pinion set would be ideal, but I have never met this idea on quattro gearboxes. Why would someone make the whole engine run backwards, instead of just a reverse ring/pinon set? I guess there is a problem, what I don't see now, and that make this impossible...

Ooops, I found it...

"But the reverse cut ring and pinion set are only half the equation. The other part involves whether or not there is room in the differential housing for the ring gear and diff to be flipped. The Audi 016 and 01A trannies aren't designed this way and it's just by some miracle that the Subaru 5MT has room to flip the differential."

Looks like this is a dead end...

Mon Dec 05, 2016 11:16 am

Something I've thought about (really no more than a thought), is installing a hydrostatic drive for the front wheels using a centered diff (locker would be nice) and axles with CV joints.

Of course, it would require a hydraulic pump, hydraulic motor, de-couple of some sort, controls, high pressure hoses, etc.

Just a thought!

Mon Dec 05, 2016 11:34 am

krumelmonster wrote: Why would someone make the whole engine run backwards, instead of just a reverse ring/pinon set? I guess there is a problem, what I don't see now, and that make this impossible...

Ooops, I found it...

"But the reverse cut ring and pinion set are only half the equation. The other part involves whether or not there is room in the differential housing for the ring gear and diff to be flipped. The Audi 016 and 01A trannies aren't designed this way and it's just by some miracle that the Subaru 5MT has room to flip the differential."

Looks like this is a dead end...
It is likely because having a custom-made reverse R&P made is 1,000's of dollars vs. mainly time (for someone with the skills) to reverse the motor and run a few few hundred dollar gearbox. Unless someone's business plan was to offer reversed R&P's and/or trannys (such as SubaGears is doing), it likely would not be financially viable for most folks.

Mon Dec 05, 2016 12:21 pm

vanagonjr wrote: krumelmonster wrote: Why would someone make the whole engine run backwards, instead of just a reverse ring/pinon set? I guess there is a problem, what I don't see now, and that make this impossible...

Ooops, I found it...

"But the reverse cut ring and pinion set are only half the equation. The other part involves whether or not there is room in the differential housing for the ring gear and diff to be flipped. The Audi 016 and 01A trannies aren't designed this way and it's just by some miracle that the Subaru 5MT has room to flip the differential."

Looks like this is a dead end...
It is likely because having a custom-made reverse R&P made is 1,000's of dollars vs. mainly time (for someone with the skills) to reverse the motor and run a few few hundred dollar gearbox. Unless someone's business plan was to offer reversed R&P's and/or trannys (such as SubaGears is doing), it likely would not be financially viable for most folks.

is not the main thing in reversing the motor rotation the need to change the camshaft?? I think that is how they used to reverse rotate the Corvair motors. I bet you could get a cam place to grind a reverse cam for you. I suppose you'd need to mess with the oil and water pumps too.

very interesting project.

Mon Dec 05, 2016 12:52 pm

AndyBees:
I know absolutely nothing about it, but maybe this will lead to the solution, great!

vanagonjr:
Thanks, I've never thought that. But seems logical. Unfortunately I don't have the skills...

Mon Dec 05, 2016 1:10 pm

Ok, here's an other one :lol:

It's not at all my idea, as there is a vanagon in the UK (I guess), with land rover drive train, and solid axles. But it's a little bit different, I leave the wheel suspension system stock (except the lift)

Here is a picture of the drivetrain:

1. engine
2. adapter plate
3. gearbox (form an offroad vehicle, which don't heve a built in transfer case)
4. custom length prop shafts
5. transfer case
6. 2 pcs of audi quattro rear differentials (normal in the rear, flipped in the front)
7. half shaft

Pro:
- leaves the stock trailing arms in place
- the gearbox and transfer case alowes highway and offroad ratios as well
- no need to fabricate any custom gear, or box. only the prop shafts, and the mountings for the gearbox, the transfer case and the differentials

Problems:
- as a consequence of the transfer case, the van is normally front wheel drive with a switchable 4x4
- putting differential under the gearbox is I guess about 10 inches of ground clearence loss. it can be reduced with a few inches lifted suspension, and mega-tyres (it would look like a monster... :twisted: )

Mon Dec 05, 2016 4:17 pm

bluebus86 wrote:

is not the main thing in reversing the motor rotation the need to change the camshaft?? I think that is how they used to reverse rotate the Corvair motors. I bet you could get a cam place to grind a reverse cam for you. I suppose you'd need to mess with the oil and water pumps too.

very interesting project.

Stock camshafts, oil pump, and water pump. You just need to know how to trick them into doing their job when the crank spins the other way.

Mon Dec 05, 2016 4:46 pm

Or ditch the mechanical connection all together and use electric motors front and back and the engine just turns a generator. Think diesel electric locomotive or serial hybrid. Or hydraulic motors and the diesel engine turns a big hydraulic pump!

Mon Dec 05, 2016 5:15 pm

geodude wrote: Or ditch the mechanical connection all together and use electric motors front and back and the engine just turns a generator. Think diesel electric locomotive or serial hybrid. Or hydraulic motors and the diesel engine turns a big hydraulic pump!

nuclear reactor hybrid is the way to go 10 million mile on a fueling lead suits required.

Mon Dec 05, 2016 8:03 pm

I think you could omit the gas or diesel engine with a nuclear powerplant and save the complexity of a hybrid in that case :D

Mon Dec 05, 2016 8:52 pm

It was probably mentioned already, but you could possibly get by with only three portals; one on either side axle output and then one placed in between the forward output and the front diff. That way, you could use any stock longitudinal AWD trans, manual or auto. Way cheaper and easier than engineering a new bellhousing portal/clutch assembly.

Tue Dec 06, 2016 4:47 am

Zeitgeist 13:
The 3 portals corssed my mind, if they are reducing the ratio. If they are 1:1, then 2 is enough, and the front diff can be flipped (but it's only good for me with low range gearbox).

I don't know if it's a cheap solution: I only found reversing bolt on portals for 5000+ $... and 2 or 3 is needed. Or is there a cheaper way I can't see? I'd love it...

Tue Dec 06, 2016 7:24 am

take a walk thru this thread and see some earlier conversations of similar merit.
http://www.thesamba.com/vw/forum/viewtopic.php?t=470843