TheSamba.com :: View topic - 73 412 auto trans same as 73 Bus auto trans?

Thu Sep 04, 2008 6:11 pm

I have a 73 412 with auto trans. I have a chance to buy a 73 bus with a bad auto trans. Are they the same? if not will they bolt up? and how much work will it be to retrofit?

Thu Sep 04, 2008 9:45 pm

I can't remember if all the mountings and linkage are all the same or not. I do know they had the same gearing, but... different differentials. 1700 Bus had a final drive of 4.45:1 and the Type IV had 3.67:1

Fri Sep 05, 2008 6:25 am

4.45 to 3.67 would give you a lot more top end! Just what a bus needs. Swap it ALL in!

Fri Sep 05, 2008 8:09 pm

Well, VW chose that gearing for a reason - you're pushing a heavy big box on wheels. You might get more top end, but it'll be gutless to drive. When vw went to the 1800 the final drive dropped to 4.36:1 and the Bentley doesn't list what the fuel injection 1.8 or 2 liter engines had. The Vanagon automatics had 4.09:1 final drive though. 3.67 in comparison would be pretty "tall" for such a vehicle - and I'm not sure with a type IV, but the engine might not spin fast enough for proper cooling due to that tall ratio.

Sun Sep 07, 2008 10:40 am

T4's have 3.9:1, 3.67:1 first year only Euro T4, burned the trannies up. T3 is 3.67:1. I'd be cautious about running even the 3.9:1 unless your bus motor's gonna be hopped up and has gobs of low end torque. Swap the bus drive gear into the T4 trans.

Make sure the trans is still in the bus, bellhousing etc. should be swappable if needed. T4 top mounts are bolted on with a bar bolted onto the bell housing. Output shafts might be different.

73 T4 auto will have an oil pressure switch that runs the air injection (EGRish). You can sell me that switch :wink:

Long Enterprises in Sebastopol CA is a very good trans resource.

Sun Sep 07, 2008 7:43 pm

I quoted that 3.67:1 final drive ratio that was in the Clymer 411/412 manual. Yeah, I know Clymer isn't the best. But I also saw that number in a 8/70 VW type 4 workshop manual that I have here, and on the specs page it says the 411 had the 3.67:1 and the type 461 had the 3.91:1. I wasn't sure what type 461 stood for though.

I also looked in the type IV owner's manual for 1974 that are in the Technical archives here on TheSamba. But it wasn't listed. I should have looked to the 1972 manual, it says 3.91:1.

Sat Sep 13, 2008 10:33 pm

461: Type 4 Variant.

Slightly heavier car, therefore the lower final drive ratio.

Travis

Sun Sep 14, 2008 8:04 pm

The tall gearing in the T4's is one of the reasons they were known as slugs and didn't sell well. Trying to back up even a slight grade was all it took to smoke a tranny. Running a T4 final drive in a bus would likely be a disaster.

Sun Sep 21, 2008 8:15 pm

All,
I have one thing to add...Make sure the gasket between the differential and Hydrualic section is flipped in the proper direction. I did this wrong on my 73 Westy and had to pull it out again and switch it around. Not a big deal but save someone some time.

Also quick question...sorry to hijack the post....concerning this VW003 Full Automatic transmission. I have one in my Westy with a 1835 engine and just taking off and reverse can be a issue but once its moving it shifts fine and has no problem reaching highway speeds.

What could cause this? Is this a gearing issue as the transmission came out of a Type IV, I believe, and I swapped the Hydraulic section.

Thanks,
Chris

Tue Sep 23, 2008 11:24 am

As mentioned above the T4 gearing is too tall for a bus. It is also best to swap in a late air cooled Vanagon torque converter in either a T4 or a bus. The higher stall speed will get you going quicker. IIRC you want a torque converter with a "Z" stamped onto one of the mounting bosses. I haven't tried running it but I believe that the "H" torque converter out of a H2O Vanagon will work as well.

Wed Dec 17, 2008 3:26 pm

The type 4's with auto boxes were not really slugs. They just happen to all be slugs NOW.
Who here has driven a brand "new" automatic type 4 with an engine in proper tune? Doubtful that any of us have.

All of the automatics in type 4's I have ever driven are old. The youngest I got was on my very first car. It was a 1972 411 four door with 55k miles. That was in 1979. When the engine is properly tuned....and the tranny is good shape, they get up and go quite well.

The real variations as to whether one ran well or not had to do with a combination of the high gearing....and any perceptable loss of torque or efficiency.

The actual tuning from the factory of D-jet was really all over the planet. They all ran well....but any real loss in torque (very easy to do) and it was sluggish getting that torque converter spooled up.
The main flaws in tuning, that seriously caused notciable power loss were:
(a) Ignition issues. The stock ignition was spotty and the dizzy had lots of slop in the advance springs.
(b) The vast majority of automatics on this continent had the deceleration dash-pot for throttle closed. Very tricky adjustment.
(c) Valve adjustment. You can lose an easy 10% of your initial torque off the line this way with D-jet
(d) Extremes of external temperature and the affect it had on CHT reading and baseline fuel mixture
(e) Fuel pressure stability in hot weather...especially if teh car is over 30k or 3 years (fuel pump and regulator wear)
(f) the generaized state of tune that the MPS's were given.

But....the main issues that cause sluggishness with type 4 autos...is age and wear.
How many of you have done what you ar e suppossed to have done maintenance wise....with your automatics?
That means that by 50-70k miles (no later than 70k)...new seals, o-rings and gaskets between thedifferential and transfer cases.
More importantly you must adjust the bands, fix all vacuum leaks, properly tune the engine....and only then...get the car on the road with service plugs removed and pressure gauges attached so you can do teh driving pressure test on the main pressure loop while adjusting the modulator valve to correctly set shift governance to the now less than new-car vacuum signature your engine has.

You would be stunned at how well a tightly tuned autobox with a 3.91 or 3.67 final drive runs....when you are actually putting out factory advertized torque. Ray