Transmission Question for Buggy Build

[bvanetten]

I'm in the planning stages of building a 4x4 buggy.  using a 1.6TD and a longitudinal automatic tranny.  The motor/transaxle will be mid engine mounted transversely behind the front seats.  The spider gears will be welded and the CV axles will act as driveshafts for the front and rear axles.

I'm having a hard time figuring out what auto transaxle would work.  From what I can tell an auto transaxle was never mounted to a 1.6 from the factory and sold in the USA.  I would prefer a non electronic tranny (OD and Lockup features can be electric).

Any ideas on what trannys would work?  VW, Audi?


Bruce.

[bbob203]

A quantum diesel transmission is probably your best bet.

[bvanetten]

So it looks like 1973 through 1988 Passat's/Quantum's had longitudinal mounted engines with fwd 3 speed auto transaxles.  I wonder how rare these are?  Time to call some parts yards.

Any other possibilities?

[CRSMP5]

very common and robust till the seal between the auto and final drive fails... then the final drive wipee out..

auto sectionn samme ...  final drive is the bell housing. that is the item you need most. .if bolted to a 4 banger fits no issue..

but how do you plan to make 4x4??

[Jetmugg]

If I understand, you are going to use the 2 output shafts of the FWD transaxle to feed power to 2 separate differential & axle setups (like would be common in a small 4wd truck)?

That thing will have some extremely low final drive ratios (like maybe 12:1)

Please start a project documentation thread for this one - I'm sure we will all be very interested.

Steve.

[CRSMP5]

 

that would be silly design then... to transverse mount the engine to use that tranny would be off...

id use a mk2 one, set it up longituduinal.. mid engine style, flip the diffs (front/rear ends) to get 3 forward gears and a reverse..

[vanbcguy]

Why not just get a Toyota 5 speed and transfer case? Then an Acme adapter plate, boom. All bolts together.

Or an auto if that's your speed!

[theman53]

I am putting a VW engine in a Jeep and I am building an adapter similar to a member here *410* did for a Toyota. This could be an option for what you are doing if you found an auto that you liked but wasn't compatible or on the acme list. Maybe something with a divorced transfer case? I am just throwing out options to get you thinking, not trying to discourage you in any way.
My thread is in the Non Vw group diesel section on this forum. I think 410 mainly posted his in the TDI section here.

[745 turbogreasel]

There is a 3 speed auto option that came on a few Rabbits.  It was pretty slow, and might not like a turbo, but any gas 8v auto should bolt on if you can find  the torque convertor parts.

If he 's crawling, 12:1 reduction will  be sweet, my friend and I almost tried to build a bobcat  that way, but ended up extra cabbing a caddy instead.

If you can fit an early Audi trans, you can have a PTO/brake where the rear drive shaft wold have been,  and selectable center diff locker.

[CrazyAndy]

I like the idea of running each axle set off one side of the trans you'll select.  As far as that option, my recommendations of older quantum transmissions is in line with everybody else.  But then I was thinking, if you will be doing that, why not run a transverse transmission in a longitudinal layout? 
Think of it this way:
-The setup would already have clearance past the engine for the drive shaft
-You could still lock the diff, or even get a spool which is available from drag parts manufacturers
-You wouldn't have to make the power go 90 degrees out of the flanges like if you were using a longitudinal trans
-Transverse auto transmissions are more plentiful than their older longitudinal counterparts, with more gear ranges to choose from
-The layout would be more compact than having to run a comparatively longer transverse tranny with PTO adapters for the front and rear axles
-This layout would not have as much driveline friction that if you had to run angle boxes.

Here's a basic photo comparison of that I'm talking about (right) vs. what I think you are thinking of doing (left).  Forgive the crudeness, as it was made in 5 minutes.


Don't you think that that may be a more efficient layout?  You could even put the engine and trans over a little to center the weight of the main drivetrain components, and let the CV/U joints put the power to a centrally mounted diff.Admittedly, this was the first idea that came into my mind, so there is probably a good reason for you selecting this option (limited space in chassis etc.), but I thought I'd just propose the idea.

Last question is this; why an auto?  Because it's better for rack crawling?

[Jetmugg]

I think that the diagram for the OP's idea should have the engine mounted sideways if I understand his initial description.

[Jetmugg]

Early Dodge Omni/024, Plymouth Horizon/TC3, etc were commonly available with auto trans, and are a direct bolt-up to VW Diesel engines. Those cars came with 1.7 VW gassers.

[bvanetten]

Ok, bunch of questions to answer.  I should probably clarify what I'm planning and why (always up for suggestions).


I've done the sammy diesel conversion thing.  Great rig but it suffered from a bit of scope creep.  Ended up being 1.6td with all toyota mini truck running gear (W56 5 speed, dual t-cases, toy axles, lockers front and rear), full cage, 33's, swingaway tire/gear tailgate, blah blah blah.  Ended up being a 3400lb pig.  Fun pig but a heavy pig none the less.  And this is what started my problems.  3400lb 4x4's don't fit in Toy Hauler trailers most of the time.  even if you get one to fit the floors are not rated for that kind of load... unless you get a custom built racecar trailer with living quarters $$$$.  So the rig ended up sitting.  Tried to convince the wife to go with a truck camper and we would flat tow or trailer the toys... no go, she is used to the space of a full size camper trailer.  Got a Rhino, kinda worked but just don;t like them much and they are expensive for what you get (it's for sale btw).  Saw a picture of a super lightweight buggy and the wheels started turning in my head (always leads to trouble).  Scavenge parts off of the unused sammy and build a lightweight buggy (under 2k lbs) for 3 people that fits in a toyhauler.  I have a 1.6 lying around to use (the 1.6td in the sammy is now sitting in my caddy).

I like manual trannys but with the design I have in mine the linkage I would have to fab would be tricky.  The wife would drive it if it was an auto.  It would be a general use trail rig, 50 mph max (probably 45 and under) with the ability to crawl when needed.Attached is a crude drawing of what I'm thinking. 

Transverse mounted motors/transaxles when mounted longitudinally take up a lot of space lengthwise and you are limited to mounting them one way so your driveshafts are not to short and the rotation is such that you go forward and not backward.  Honda motors are the exception to this as they spin the opposite direction to most motors.  If you don't run a honda you have to flip the axles to get the correct direction of rotation.

By using a FWD longitudinal mounted engine/transaxle assembly (mounted transversely) I don't have axle length issues as I can mount the motor in the proper orientation to allow for correct driveshaft spin direction.  I don't take up as much space lengthwise keeping the rig short.  the seats can be moved forward a bunch making for a fun rig to drive.

Pics of examples of what I'm thinking are attached also.

[CRSMP5]

but the longitude tranny is very very long... you will be too wide for a great trail runner...


to make it mid engine with tanny to the back, again you will have to flip the axles front/rear... i do not see the room issue... unless it was 4 seater...

this way the axle to the front will also be closer to middle.. to make transverse in the middle #1 and 2 will stick out further then the rear tire..

shifter linkage... hydro clutch... it can be done.. not as hard as you think.. expecially if you used a 02a.. 2 shifter cables.. and hydro line.. look on tdi club for th emk4 kit car info.. see ho whe did his cables.. he rear mounted a 02a/02j style in back..

[bvanetten]

Hmmm,

Anyone have measurements of the manual and auto trannys?  Length of 1.6 and 020 is about 34 inches.  Even if the auto stretched that to 40 I'd be in good shape.  I'll lookup the emk4 car.