Bluesky Thinking - Rear Engine AWD VW Bus

[zerobalance]

Sorta 4x4 related, figure I'm safe in newb.

Rear engine vehicle (VW bus), thinking of ways to make it all wheel drive. There were syncro Vanagons, that used a drive off the main shaft of the trans for a front output like so:

They work ok, but are stupid expensive and not really tough. I've been trying to come up with a way to have a modern rear engine, with a driveshaft to a diff in the front. The probably easiest option is to get a subaru transmission and run a reversed ring and pinion, still expensive and not super robust.

The ideal solution would be using the engine transverse, with an awd transmission, then figure out how to get the formerly rear output to the front wheels somehow, this would use all off the shelf parts that are pretty tough and easy to find everywhere. The problem is how to get the front drive pointed the right way.

How the OEM version is layed out

Who has some crazy ideas? Could be other than VW parts, I can machine adapters and whatnot. Ive been considering how I can modify the rear diffs to be a sort of angle box, they have a 1:1 ratio and I have 7 or 8 of them.

 

[Bebop]

Already went down this road. The best solution is 2 gear portals.

 

[bdkw1]

Regular subi trans and swing axle gear reduction box's modded to be IRS. Fixes rotation and gearing all in one. If you start with a swing axle buss you have half the parts you need.

 

[zerobalance]

Already went down this road. The best solution is 2 gear portals.

Please elaborate, I have a bunch of bus reduction boxes I considered using to reverse the output of a passat or A4 transmission, but the way the torsen diff is set up in them would make it want to be a FWD vehicle. The reduction boxes would screw up the ratios too, so the output would be geared different.

 

[bdkw1]

Or the other idea I had was making portal box's using quick change wide gearsets. Then you could dial in your gear ratio. Unit bearings and a couple stub shafts to make it all spin.

 

[zerobalance]

Regular subi trans and swing axle gear reduction box's modded to be IRS. Fixes rotation and gearing all in one. If you start with a swing axle buss you have half the parts you

The gear reduction on the bus boxes would screw up the ratios, so you would have lower ratio at the rear output than the front.

 

[zerobalance]

Or the other idea I had was making portal box's using quick change wide gearsets. Then you could dial in your gear ratio. Unit bearings and a couple stub shafts to make it all spin.

That would be a possibility, the boxes would be easy enough to make, the gears would need to be something off the shelf ideally.

 

[bdkw1]

The gear reduction on the bus boxes would screw up the ratios, so you would have lower ratio at the rear output than the front.

Your going to need them in the front too. Look at schwimmer wagon front ends.

 

[zerobalance]

Your going to need them in the front too. Look at schwimmer wagon front ends.

They don't have front portals

 

[aczlan]

Ford or Haldex bevel gear case on the output shaft of the transmission and feed the correct gear ratio diff at the front axle?

Aaron Z

 

[Thatg9659]

Nvrmnd

 

[zerobalance]

Ford or Haldex bevel gear case on the output shaft of the transmission and feed the correct gear ratio diff at the front axle?

Aaron Z

The transmission from something like an R32 or Audi TT already has a bevel box for the rear diff output, but the output would be facing back with a rear engine.

 

[arse_sidewards]

EJ25 swap using an AWD trans and 2-gear portals. Flip whatever you use for a front diff. Select your portal ratio to match up with a front diff. Subaru trans are not exactly 1:1 front to rear so read up.

Manuals are 50-50 split. 4spd and 5spd autos are FWD biased making them RWD biased in your application.

You can try and make European garbage work but it will be more work and more money for less results.

 

[Bebop]

Please elaborate, I have a bunch of bus reduction boxes I considered using to reverse the output of a passat or A4 transmission, but the way the torsen diff is set up in them would make it want to be a FWD vehicle. The reduction boxes would screw up the ratios too, so the output would be geared different.

Portals front and back. How is that complicated

 

[zerobalance]

EJ25 swap using an AWD trans and 2-gear portals. Flip whatever you use for a front diff. Select your portal ratio to match up with a front diff. Subaru trans are not exactly 1:1 front to rear so read up.

Manuals are 50-50 split. 4spd and 5spd autos are FWD biased making them RWD biased in your application.

You can try and make European garbage work but it will be more work and more money for less results.

I'll never put a subaru engine in a vw, I guess they work, but that is not my thing. If I were to use portals to reverse rotation, I would just use a passat or A4 transmission, so there were no adapters and such invovled. Vanagon people use them now, but flip them upside down to correct the roation, but then there obviously is an adapter to fix the upside down bellhousing. For me, subaru parts are far more money, I have a building literally full of VW stuff, I know them inside out, I have the ability to program ECUs in house.

 

[zerobalance]

Portals front and back. How is that complicated

It's a bit overly complicated, and portals are not exactly just available off any old junkyard car

 

[zerobalance]

I suppose the easiest thing to do would be to figure out an off the shelf 1:1 gearset, make a portal box and attach it to the axle outputs on a transaxles like this. That would be a lot easier than trying to machine a gear to accept a stub axle at the wheel end and it would eliminate the issue the portal box giving extra leverage and stress at the wheel end. That setup would only take two portals and would minimize custom parts, which is the goal

 

[BDK]

There is no substitute

 

[Bebop]

I suppose the easiest thing to do would be to figure out an off the shelf 1:1 gearset, make a portal box and attach it to the axle outputs on a transaxles like this. That would be a lot easier than trying to machine a gear to accept a stub axle at the wheel end and it would eliminate the issue the portal box giving extra leverage and stress at the wheel end. That setup would only take two portals and would minimize custom parts, which is the goal

SCS and Winters has gearsets available.

 

[zerobalance]

There is no substitute

I would love to do that, but those are just silly money.

 

[zerobalance]

SCS and Winters has gearsets available.

I hadn't even considered using a quick change gear set. I wonder if they will sell 4 of the same tooth count gear rather than a reduction set

 

[Bebop]

I hadn't even considered using a quick change gear set. I wonder if they will sell 4 of the same tooth count gear rather than a reduction set

1:1 is a standard ratio that is available from both manufacturers.

 

[bdkw1]

It's a bit overly complicated, and portals are not exactly just available off any old junkyard car

I thought you said you had a bunch of swing axle ones?

With the spring plate and shock mounts, it wouldn't be real hard to make an upright that bolted to them. Stub axles are also easy, they have been converted before.

 

[zerobalance]

I thought you said you had a bunch of swing axle ones?

With the spring plate and shock mounts, it wouldn't be real hard to make an upright that bolted to them. Stub axles are also easy, they have been converted before.

I do. The problem is in the gear reduction. It seems like trying to do 4 wheel portals is way over complicating for what I would want to achieve, not building an ultra 4 car

 

[bdkw1]

The problem is gearing. Unless you are planning on running 26" tall tires any street trans will be geared way to tall. Portals add complexity but solve a lot of issues.

 

[zerobalance]

The problem is gearing. Unless you are planning on running 26" tall tires any street trans will be geared way to tall. Portals add complexity but solve a lot of issues.

I guess I should have added that if I can figure all this out, it will be using a common rail TDI engine. The gas transmission gearing works out with a 30" tire.

 

[Bebop]

I do. The problem is in the gear reduction. It seems like trying to do 4 wheel portals is way over complicating for what I would want to achieve, not building an ultra 4 car

We don't really know what you're trying to achieve. Tons of people offroad 2WD VW based platforms, not like 4WD is mandatory.

 

[zerobalance]

We don't really know what you're trying to achieve. Tons of people offroad 2WD VW based platforms, not like 4WD is mandatory.

Fair enough. Basically trying to build something similar to a Syncro Vanagon on a split bus platform, but with modern parts that are actually available, and don't cost a mint. Syncro vanagon transmissions cost a mint, so looking at a way around that with stuff on a bunch of cheap, later model cars.

I already have a regular VW that goes offroad, I'm exploring thinking outside the box and doing something cool.