TDI sand rail feasibility?

[mlemorie]

I picked up a cheap sand rail last weekend on a whim. Needed an engine and other general work, and I finally was able to get around to inspecting it better last night. It needs more work than I initially thought, so now I'm considering putting my old BEW back together and setting it up to run with that instead. The 113 gearbox is nearly corroded through in some spots, and the left side frame horn is roughly 60% there at this point. With the fab work needed, I figure it would make sense to do ALL of the work now instead of doing it again later like I was initially planning. Trying to decide on a transmission to go with though. I'll need to convert to IRS as is, so I was trying to decide on a slightly more modern box that could handle some modified TDI power but I'm coming up blank other than 996/997 6mt boxes. Any other gearbox suggestions? Bonus points if they'll bolt up without much trouble lol.

 

[mlemorie]

The buggy in question

 

[oilhammer]

Speaking from experience, it is amazing what a money fire those things can turn into.

The Transporter gearbox, specifically the preferred 091 (1976+) is much sturdier, and there are some aftermarket improved beefy parts available. They get expensive, especially if you have no core to start with. You could easily spend $5k on a built 091 box and drive axles and flanges. If that one is already a swing axle, you'll need to modify it quite a bit, or cut it out and weld in a whole IRS frame horn and start over.

I saw a rail buggy a few years back that they just made up a cage to mount the I4 engine and gearbox transversely (so mid-engined transverse, like a Toyota MR2 or Pontiac Fiero) that not only allowed for a 90% totally stock powertrain (this one was a 2.slo gasser from a 2002 Jetta), but a nice well balanced package and was frightfully quick as 115hp moves ~1300 pounds of car pretty good.

It also made for a car that was actually driveable, as the powertrain was slightly ahead of/over the rear wheels. I can tell you, if you hung a BEW off the ass-end of that buggy, even stock, anything over half throttle and you won't be able to steer. At all. That's why so many buggies got spindle mount front wheels (no brakes on the front at all, as they instantly lock up if used) as well as "cutting brakes" for the rear, where you can yank one of two levers to individually brake the rears in order to steer the car. It is awful, and dangerous, to drive like that. They suck. Been there, done that, got the T-shirt. There is a reason why all modern new side-by-side UTVs are mid-engined.

 

[mlemorie]

My concern with the transverse mid engine was the unequal length driveshafts and trying to get more travel out of them than a sedan asks for lol. I have been reading on the bus boxes, and I don't know if I'd necessarily want to go that route. 1 due to the price like you mentioned, and 2 it would still likely be strained due to the high torque of a tdi. I suppose I could mid engine it and toss an 01E or something of the like in it since the frame would need to be extended already. I'm not sure if extended arms would be enough to position the rear wheels properly, or if I would end up needing to move the torsion tube back under the engine to reduce the stress on it. A lot of the parts I've seen so far for this thing have been on the half way cheap side. I say that with my main comparison being MK4 tdi stuff, and E1 Cayenne offroad parts lol. It's a bummer that something cheap like Hondas don't entertain me as much

 

[PickleRick]

Some of the Fiero guys have ran the Pontiac G6 6 speed manual transmission with various engine set ups from a 3800 to SBC V8. So strength and mid engine set up would not be an issue. There are also several TDI to Chevy 90 and 60 degree engine adapters available now. There's a Fiero TDI conversion, many years old now, build on here worth looking into if that fits your bill.

This set up wouldn't be on the cheap side.