Auto Trans ALH 1.9TDI - what ring and pinion gear?

[swissarmychainsaw]

1984 Vanagon Adventurewagen
ALH Diesel TDI 1.9
Bosch Mechanical Injector Pump (from rover?)
15" wheels (25.5 tire diameter)

I'm pretty sure my auto trans has the stock 4.09 gear ratio and I'm ready to take the next step in getting this properly set up.

my "research" says: From 1996 through 2003, the 1.9-liter TDI created 90 horsepower (hp) at 3,750 RPM.

This van is ok driving around town, and will do 65 on the freeway, but climbing mountains passes and hills it really struggles.
Honestly I want to keep up with freeway traffic better.

So I'm doing a couple of things:
1. Making sure the motor is working at full capacity
2. Sorting out the gear ratios.

Can y'all give some advice on what gear ratio I should put in this?
It's an expensive thing, and I don't want to do it more than once!

Thanks!
Nick

[MarkWard]

Generally, you'd want to go to a taller ring and pinion to lower engine rpms at highway speed.

Problem is, that will aggravate your hill climbing experience. For climbing you want a shorter ring and pinion.

With an automatic, you really can't do both.

What you should be looking at though is how the accelerator pedal cable is connected to the automatic transmission. You don't mention if yours is a true flybywire TDI or a TDI that's been converted to a mechanical pump.

In both cases, the automatic needs to be part of the accel pedal and adjusted properly.

You can look at the factory manual to see how to adjust the automatic and accel linkage to get an idea of how it functions properly. The vanagon diesel did not come with an automatic, so some adaption would be necessary.

[swissarmychainsaw]

[?Waldo?]

As Mark describes there are two issues. One issue is having gearing so that the engine is spinning reasonable RPMs at highway speeds. The other issue is having adequate performance in order to climb hills well. If you don't have enough power to climb hills @65 with an mTDI ALH fitted to an automatic with the 4.09 R+P then you have a performance issue. I would suspect that the mechanical pump fitted to your engine is either incorrectly built, poorly tuned, or the turbo is not generating a reasonable amount of boost. If you attempt to lower the RPMs with a ring and pinion swap, your performance will be even worse proportional to the change in rpms. Adjusting the accelerator linkage might be helpful if the pump accelerator lever is not travelling far enough.

[MarkWard]

You can't compare my setup to yours, but seems my ALH is happiest around 3000 rpm at highway speeds. My gearing and tires put me at about 70mph at 3000 rpm.

With slightly larger nozzles, I'm able to pull a lot of grades in 4th gear at 70 mph. It's probably not good for the transmission or the engine, but I don't really worry about it.

[swissarmychainsaw]

Thanks for the feedback so far.

I went to my friends place who is a diesel guy and knows a bit about the VW diesels.
We did a few things:
1. Adjusted the throttle cable so the kick-down works better. (you floor it, you downshift) - no longer at 5/8ths throttle or whatever it was.

2. Confirmed the Turbo is correct for this motor, did a sanity check on it (disconnect the tubo outlet just to see if it was pushing a bunch of air - it was) and replaced some fuel return lines from the injectors which were cracked. And some copper washers at the fuel return at the Mechanical injector pump.
This stopped any air bubbles in the "view port" on the return line.

3. Showed me where to put EGT and Boost on the motor (seems simple enough).
4. Test drove

His feedback was that the motor was putting out enough power. Nothing jumped out at him as being "wrong". His opinion of the "hard to climb hills" and what not is that the engine and auto trans were a bad match. "It feels like you are always in the wrong gear."

So ... next I'll put a boost gauge in it, see about a Tach and maybe an EGT and see if we can get actual data.

[?Waldo?]

To be clear, I own a '91 mTDI ALH with automatic trans and it drives very well. It has excellent performance - much better than any WBX Vanagon. My only complaint is that the RPMs are very high at highway speeds despite already having a taller 3.7 ring and pinion.

You say it is the 'correct turbo for the engine'. The ALH came with the Garrett VNT15. If that is that is the turbo that is currently fitted, then more investigation is in order. The VNT turbos are advanced in design and stock are controlled by the electronic engine management computer. Because your engine does not have the electronic engine management, if your turbo is the VNT15, then that begs the question, what is controlling the vanes? Without the turbo producing appropriate boost pressure, the van will be seriously lacking in performance.

Post some pics of the turbo.
_________________
I am a high-functioning autistic into VW diesels and Vanagons along with other things that are unrelated to this site.

[swissarmychainsaw]

This is a fair point.
Edit:
My understanding is that for it to be VNT it needs a controller of some kind, and I don't see any.
Which leads me to think it's not a Variable anything Turbo.


You can get larger images on the smugmug page this are liked from.
Also if you want better ones of any section let me know. I can't tell anything from these photos myself.

This says 049

Stamped: 0303

[?Waldo?]

That is not a VNT15. I believe that is a K03. That is a wastegated turbo and does not need to be computer controlled. Installing a boost gauge would be a good next move just to confirm that you are getting decent boost.
_________________
I am a high-functioning autistic into VW diesels and Vanagons along with other things that are unrelated to this site.

[swissarmychainsaw]

Ok great. That's next.
Thanks for the feedback, it's helps a ton! Much appreciated!

[swissarmychainsaw]

BTW the number stamped on the Injector Pump are:

1 465 530 746
13815

Anyone help ID what that Pump type is and what it might be off of?
I'm getting a sensation these are not well matched components.

I have to travel a bit this week, but will look at getting the boost gauge installed.