Audi 90 quattro TDI: gearing questions

My CQ has a throttle pot controlled by the throttle cable. It's right on the throttle body. It's been working fine for 24 years, so I don't see why it wouldn't work in your application.

bbob203 said:

Are you saying use the throttle cable to actuate the pot??? I guess that would work. The mk4 dbw pedal takes up a lot less space and you could easily adapt it to bolt up to the audi firewall Im sure.

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yes, thats what I am saying. It would be mounted to maybe the firewall somewhere. Just making sure the enclosure would be ok with underhood temps/possibility of moisture. It looks pretty well sealed.

Use a pedal assembly from a Euro B4 tdi...

Scott_DeWitt said:

Use a pedal assembly from a Euro B4 tdi...

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i will look for one of those. I have a pretty tight budget on this build (my woman moved out and now im paying the whole mortgage alone), so certain expensive euro bits might have to be sacrificed for less than ideal setups. Ah life, sometimes you are a cruel *****.

I use 6gear vom 2.5tdi a6/a4 DQT it´s with 4.11
it fit´s on 4,5 and v6 cylinder vag engines
gas pedal on my t89 coupe is selfmade for edc15

look, I actually did something on this project this evening and pulled the 7a.

First test fit in the bay



this test has revealed that i have an oil pan interference with the subframe and an oil filter collision with the factory chassis side engine mounts. The solution appears to be an oil pan from any longitudinal vw or audi with a 4 cylinder and the oil filter solution appears to be a mount/cooler from a longitudinal 1.8t.

Nice progress!

vtpsd said:

this test has revealed that i have an oil pan interference with the subframe and an oil filter collision with the factory chassis side engine mounts. The solution appears to be an oil pan from any longitudinal vw or audi with a 4 cylinder and the oil filter solution appears to be a mount/cooler from a longitudinal 1.8t.

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Use a pan, pickup and oil filter/cooler from AEB 1.8t

trial fit #2. AEB oil pan, filter mount and starter allowed it the engine and trans to actually bolt together for the first time!


AEB starter


I am planning on making a mount that replaces this one and grabs the factory audi rubber chassis side mount


AEB oil filter mount is key




AEB oil pan


exciting bonus, a little tweaking of the audi power steering pressure line and it fits the TDI pump!!


had to twist this coil a bit to get the PS line to fit.

It looks right at home!

thanks Rich! I appreciate your advise as I go along.

busted some more out today. Going to the dominican for a week, so i wanted to make some more progress before i peaced out.
i had this crappy winch plate that i took off my 4runner that i cannibalized for the plate.


high tech bolt pattern matching


measuring for back spacers


mounts completed


drivers side mount, gusseting will be added to these


passenger side mount


final driveline angle. seems good, but the oil cap hits the hood. Might need to find a way to lower that.

You can take that funny elbow thing off the valve cover I think. Mine has one.. I like it personally! But someone advised I could remove it should I choose just didn't elaborate on the process.

yea, it looks like it might just be an extension. I like it too, but to have the engine at the angle i want it seems to be touching the hood. Ill investigate further.

I'd be welding some gussets into the mount brackets. They look a little too long not to be reinforced in some way.

i plan on gusseting the passenger side bracket. I think the driver side is ok, its much shorter and direct.

Im taking the opposite approach or will be when the time is right. I want to swap a Quattro system into my mk4 jetta tdi. I know it will be a lot of work but worth it for the perfect sleeper. Your project looks great gives me plenty of inspiration.

This project is NOT actually dead. I became single after 7 years of relationship land since I started this project. I've been spending lots of time and money doing the things that a recently unchained man does.

BUT, I have gotten the bug to start wrenching on this again.

I didn't want to pull the motor apart, but I could not accept the amount of veggie oil fossils that were in the intake ports and on the back of the valves. The ports are so little and goofy on the TDI that I had to pull the valves to get them properly clean, so here it is.

Suppose its time to update this,
Because I'm a diesel newb, I had the head decked to ensure flatness. They only took off 5 thou, but in hindsight, it was probably not necessary. Since diesels have such tight piston-valve clearances, I realized that I new had shaved off .005" of the .015" clearance that the factory had the valve to piston clearance. I got creative and decided to carefully measure the valve length and shave the ends off on a bench grinder. :lol: I then spun the valves in a drill and polished them down on a straight edge with various grades of sandpaper. They are nice and smooth and are back to the factory clearances. Time will tell if this explodes, but I think not.


head all re-assembled.


spend a bunch of time cleaning, scraping, needle scaling, sandblasting (every bolt) and painting engine parts.




Then I made a little block off plate for the 1.8t turbo drain. The tdi drains back into the block, so i didnt need this port. I used an old drain from a 1.8t and cut off the flange and plugged the hole.

new timing components. There was an ungodly amount of veggie oil fossils everywhere here from a leaking injection pump main shaft seal.

coming together






did a little work in the engine bay before putting the engine back in (hopefully for good this time)
new tie rods for the car


new rack boot


vacuum brake conversion

then i decided i wanted a working factory oil temp gauge, so i removed my cap on the oil drain in the 1.8t pan and tapped it for the audi factory oil temp sensor.

engine going back in









spend a good 6 hours on the floor learning the wiring harness.


hell hole


getting it pared down


eliminated wiring


purchased a tdi 01e 4.11 6 speed quattro trans, this will make the whole project worth it. It became apparently to me after driving around my mk4 in 4th gear that I would need something with TDI gearing to make this swap worth the effort and money.

oh yea, and also....
https://www.youtube.com/watch?v=P8lfaTSdElE
started right up on the first try. Very very pleased about that. The wiring is obviously everywhere, I just wanted to make sure my wiring theory was correct. Now its time to start organizing the bay and wrap the harness.
I also reinforced my engine mounts big time. Didn't get a pic of those yet, but they are much better than before.

Right on sounds really good too! Def on my list of swaps I would like to do!

thanks man! I am very happy to hear it whistling away.

Excellent progress!

Thanks Rich! I appreciate you pioneering the way for a lot of this swap. Also appreciate seeing your excellent results with you 80 TDI.

glad to see your still working on it! Looking good

Love the Vermont castings defiant in the background... must be warm in the winter

Ifixit said:

glad to see your still working on it! Looking good

Love the Vermont castings defiant in the background... must be warm in the winter

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Thanks man! Hopefully you will see it around this coming winter. Yes, that stove in the insulated shop makes it great to work in the winter. I can work in a t-shirt after the stove has been burning and hour.