adjust auto transmission line pressure

KERMA

Vendor , w/Business number
Joined
Sep 23, 2001
Location
here
TDI
99 beetle and 04 jetta
Here is an easy, free mod you can do when you service your auto transmission for fluid and filter change, or whenever you have the pan off. I found this while developing my new plug-in "tuning box" for these transmissions (an ugly but functional working prototype is in my car right now)

Here is a picture of the valve body from underneath the car, with the pan and filter removed:




Here is a closer view of the area around the adjustment:



The funny cap srew with the "star-shaped" notches is what you will turn to make the adjustment. Here is a picture of the hex wrench in the appropriate location:



About the only "special" tool you need is this shortened 3mm hex wrench. I ground mine down to about half the length onthe short end so it would fit. The fitting is actually for a T-20 torx, but it is a very tight fit unless you want to remove the valve body from the transmission, not recommended. 3mm hex works in a pinch if it is shortened.


***Warning***

DO NOT TURN THIS "SCREW" IN THE OUT DIRECTION TO TRY TO LOOSEN IT. YOU WILL BREAK THE LOCKIING TABS THAT LOCK IT IN PLACE.

Here is a fuzzy closeup picture of the star-shaped adjustment, from the valve body on my workbench. Note the locking tabs are broken.... Here's your chance to learn from my mistake, do not try to loosen them, only turn this in the righty-tighty direction.



How far do you turn it? On the workbench I got about 30 "clicks" out of it- you will see what I mean. In the car only about 20 clicks. Maybe I could get more if the wrench was ground a little shorter to get in there better, but it was enough.

The result: much more positive shifts. you need to see for yourself. /images/graemlins/cool.gif
 

KERMA

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Joined
Sep 23, 2001
Location
here
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99 beetle and 04 jetta
BTW just a reminder, reset the basic settings for the transmission again after you do this, to reset the fuzzy logic.
 

NYTDI

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Joined
Mar 23, 2001
Location
Mid - Hudson
TDI
1999.5 Golf TDI AUTOMATIC trans. GLS w/PLX package silver/black cloth
Very interesting!

Do you think a torx screwdriver bit would fit in OK, then I would turn it w/one of those little side handle rachet bit drivers?

I'm really interested in your up coming tweaker box for the tranny.
 

NYTDI

Veteran Member
Joined
Mar 23, 2001
Location
Mid - Hudson
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1999.5 Golf TDI AUTOMATIC trans. GLS w/PLX package silver/black cloth
Yeah I understand that the pan has to be dropped to get to the screw. I've done 2 F/F changes so far.

I was just asking if KERMA thought that a side rachet drive bit could be successfully used in there.

Hey KERMA I have a spare TCU. Would that be any use to you for futher development?
 

KERMA

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Joined
Sep 23, 2001
Location
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99 beetle and 04 jetta
NYTDI:

If I could "borrow" the TCU for a while, it might help. MOstly I want to look inside and get a feel for some of the components they mount on the board.

Right now I want to run my box on my car and see if anything blows up before I risk anyone else's. Feel lucky? I could send you a prototype, if you don't mind cutting a few wires inside the harness...

So far, so good, but it will definitely need a few internal adjustments in the valve body for the most benefit. For starters, the main pressure reg valve needs to be re-worked to allow more flow to the TC. It is amazing that the TC works at all as restrictive as that thing is. It's also kind of strange because if it opens up TOO far it just dumps pressure back to the sump. It's like there is a fine balance that has to be maintained between no TC flow and dumping all the pressure to the sump. There can definitely be more flow if the valve is machined a little different. A nice side benefit will be more cooling flow because ALL the flow to the TC goes through the cooler first. Maybe if I have time I will work up a simple schematic diagram for the hydraulic circuits to help explain what I am doing.

I would say, based on my experience with this simple adjustment the last couple days, that it is definiely worth doing if you have the pan off. The car responds much better to the throttle and it is obviously better coupled to the wheels, more power getting down. Max the main pressure and lock the clutch and it is like a rocket through 2nd and 3rd gear- right in the fat torque band no more revving aimlessly to 4k and staying there. That is no doubt hard on the equipment though. But what a hoot. I am using the torque for the first time. As a side benefit: the controller seems better behaved after all this.

The problem now is getting something together in a user-friendly package, as long as it won't blow anything up. I had to slice into the transmission harness cut some wires and solder the gadget in place, and run wires thru the firewall. I want so find or make the round plug for the valve body on the transmission so it is more plug it in and go type of thing, but as far as I can tell the plug is not available. The other alternative is to unplug wires at the TCU.

There is less than 2 cm gap between the transmission case and the adjustiong point, no standard socket wil ever fit. Even the shortest little replaceable screwdriver tips are too long. It is tight. This may be a job for... METALNERD!!! a really short t-20 is the ticket, maybe bent like a typical hex wrench so you can turn it.
 

NYTDI

Veteran Member
Joined
Mar 23, 2001
Location
Mid - Hudson
TDI
1999.5 Golf TDI AUTOMATIC trans. GLS w/PLX package silver/black cloth
email or IM me your address, I'll get it in the mail to you Mon. or Tue.
 

KERMA

Vendor , w/Business number
Joined
Sep 23, 2001
Location
here
TDI
99 beetle and 04 jetta
[ QUOTE ]
GoFaster said:
Hey Kerma,

I gather that your response to a "No User Serviceable Parts Inside" sticker is the same as mine.

/images/graemlins/laugh.gif

[/ QUOTE ]


Sorry, man. I can't help it. It's my nature. To me, that that sticker means "Tinker with me, please" /images/graemlins/grin.gif
 

zanzabar

Vendor
Joined
Oct 18, 2002
Location
Petaluma, CA
TDI
2004 Jetta BEW 5spd (dual duty track car and daily driver beater)
Update?

How's this working? Tranny explode yet? Does it shift harder (ie is it any less smooth when you're not floorin' it)?
 

KERMA

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Joined
Sep 23, 2001
Location
here
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99 beetle and 04 jetta
WOrks great.

Crisper shifting, lower rpm shifting.

I recommend this mod to everyone. Do it when you service your transmission. Quick, easy, and FREE.
 

Occams_Razor

Veteran Member
Joined
Jun 27, 2003
Location
Dayton, Ohio
TDI
Jetta Wagon, 2003, Reflex Silver
[ QUOTE ]
KERMA said:
WOrks great.

Crisper shifting, lower rpm shifting.

I recommend this mod to everyone. Do it when you service your transmission. Quick, easy, and FREE.

[/ QUOTE ]

"Lower RPM shifting"? /images/graemlins/eek.gif

My transmission already short shifts from 1st to 2nd as it is! /images/graemlins/confused.gif

Is that lower rpm shifting under normal acceleration or lower rpm shifting under wot?
 

KERMA

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Joined
Sep 23, 2001
Location
here
TDI
99 beetle and 04 jetta
I think maybe the power mods change the way it shifts. Mine was shifting too high for my liking, and had a hair-trigger downshift more or less. This tightened it up a bit. Not dramatic, but definitely noticeable.
 

Judson

Veteran Member
Joined
Jan 18, 2001
Location
Cheyenne, WY
TDI
2001 Jetta
So, does doing this just make the shift crisper, and
not change the shift points?

AFAIK, the two biggest complaints against this auto
are:

1) revving and revving instead of shifting and getting
back into the torque zone

2) shifting way too early and lugging the bejeesus
out of the poor motor

I'm actually more concerned about fixing #2. I figure
more power will help #1, as an upsolute chip didn't
help #2.

Jud.
 

KERMA

Vendor , w/Business number
Joined
Sep 23, 2001
Location
here
TDI
99 beetle and 04 jetta
Actually, rev and rev problem is worse with higher line pressure. That's where forced TC lockup comes in. You can lock that thing up in all gears once you get rolling. I do sometimes when I want to punish some poor unsuspecting ricer. This part I implemented after the racing season was already done, no way to test it at the track, but feels like good for at LEAST a good 3/4 sec in quarter mile ET.

This line pressure mod does change the shift quality some. For the better I would say.

Wish someone else would do it so I'm not the only one with first-hand experience.
 

Occams_Razor

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Joined
Jun 27, 2003
Location
Dayton, Ohio
TDI
Jetta Wagon, 2003, Reflex Silver
[ QUOTE ]
Wish someone else would do it so I'm not the only one with first-hand experience.

[/ QUOTE ]

I would do it in an instant if there was any way of backing it out if I don't like it. According to your post once done you can't go back without rebuilding the valve body to replace the little star dohickey when you back off the adjustment... Correct?
 

KERMA

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Joined
Sep 23, 2001
Location
here
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99 beetle and 04 jetta
Correct.

maybe I can source some of those doohickeys. We will see.
 

eric g

Active member
Joined
Feb 27, 2002
Location
holland
TDI
Golf IV '98 , 110hp, Highline, climatronic.
I have done that mod several time's, I work in a transmission shop. It is not always the solution for the problems in the transmission but most of the times it is.
Playing with the lock-up could be killing it specialy when your putting lots of power in low speeds in it, here in holland lock-up failure is verry common on these transmissions.
You can back it out with one click a time by bending the "strips" carefully.

Greetz Eric.
 

Judson

Veteran Member
Joined
Jan 18, 2001
Location
Cheyenne, WY
TDI
2001 Jetta
[ QUOTE ]
eric g said:
I have done that mod several time's, I work in a transmission shop. It is not always the solution for the problems in the transmission but most of the times it is.
Playing with the lock-up could be killing it specialy when your putting lots of power in low speeds in it, here in holland lock-up failure is verry common on these transmissions.
You can back it out with one click a time by bending the "strips" carefully.

Greetz Eric.

[/ QUOTE ]

Eric -

Greetings...

Not sure what you're saying here....

On the one hand, you're saying you've done this mod several times,
then on the other, it seems you're saying that doing this mod
can cause damage.

Am I reading this incorrectly?

Thanks,

Jud.
 

KERMA

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Joined
Sep 23, 2001
Location
here
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99 beetle and 04 jetta
What causes damage is the TC SLIPPING while in lockup. This comes from insufficient line pressure to hold it tight against the torque.

Higher line pressure is better for transmission longevity. The clutch slippage is designed in to make "smoother" shifts, but this slippage wears out the transmission quicker. That is why we always hear about transmission failures from the people who say "but I was always easy on it and shifted below 2500 rpm, I babied it" because the fuzzy logic TCU lets more slipping happen so the shifts are "gentler". The luxuriously smooth shifting tears up the transmission.
 

Judson

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Joined
Jan 18, 2001
Location
Cheyenne, WY
TDI
2001 Jetta
OK. That makes sense.

I'm only at 32k - I may think about this earlier rather
than sooner.

What's a standard auto tranny maintenance procedure
all about? Just a fluid change?

Thanks,

Jud.
 

KERMA

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Joined
Sep 23, 2001
Location
here
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99 beetle and 04 jetta
Fluid and filter. Do it now you may be surprised at how bad the stuff smells.
 

eric g

Active member
Joined
Feb 27, 2002
Location
holland
TDI
Golf IV '98 , 110hp, Highline, climatronic.
Jud,

Kerma allready answerd your qestion, but what i mean is: higher line pressue is better for your transmission. Adjusting the line pressure wil not affect the time when your lock-up applies. These transmission have a seperate duty solenoid for the lock-up apply pressure. Putting a high load (torq) on low engine speeds wil kill your lock-up.

Greetz Eric
 

Judson

Veteran Member
Joined
Jan 18, 2001
Location
Cheyenne, WY
TDI
2001 Jetta
Thanks. I'll look around for fluid/filter, and do this
mod, and let you all know the results.

Jud.

PS I've found a deal in the classifieds section on
the entire kit.

PPS OK, I should have the kit installed a week from
Saturday. I'll post my impressions soon after.
 

JKnowledge

Veteran Member
Joined
Apr 25, 2003
Location
Virginia
TDI
2002 Jetta GLS Silver with Leather
I have 30,000 on a 2002 Jetta that I bought with 5000 on it 6 months ago and was thinking I might go ahead and service the transmission for peace of mind. Do you guys think this is overkill? If this mod will make that auto tranny last longer, I am all for it, and may as well do it, just thought I'd get your opinions first.
 

Occams_Razor

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Jun 27, 2003
Location
Dayton, Ohio
TDI
Jetta Wagon, 2003, Reflex Silver
Since I finally got around to doing this on my New Beetle I decieded I would post my findings since Charlie helped me to get the fluid level straightend out.

The mod is relatively simple to do. Charlie explains it very well in the pictures at the top of this post.

The one point where I beg to differ is in the tool to use. I went to my local Autozone and found a kit of "L" shaped Torx wrenches. The T20 fit perfectly and had room to spare once you push in the little dohickey. I was easily able to get 30 clicks, (at least.. I lost count and just turned it in until it wouldn't turn anymore) without too much trouble.

I got the fluid level sorted out with Charlies help, (you do all know that the engine has to be ON to check the level don't you? The Bentley and the instructions on this forum don't quite spell that out.. /images/graemlins/mad.gif)

The way I finally got the correct fluid level was:

Installed a hose down to the fill tube;

Fill trans with 3 liters of VW trans fluid;

Started Vag-Com;

Started the car cold; Cycled the shifter through all positions a couple of times.

Started measuring block 005 in the auto trans controller;

Opened the drain plug with a small container under it to minimize the mess; Left the red tube level indicator installed;

No drip; Checked Vag-Com; Not quite in the test temp range but close;

Added close to a liter of trans fluid until it started dripping out;

Closed plug;

Checked Vag-com; Temp was just getting past the test temp range.

Anyway. The car shifts a bit more firmly than before. Not harsh by any means. Nice! /images/graemlins/cool.gif
 

zanzabar

Vendor
Joined
Oct 18, 2002
Location
Petaluma, CA
TDI
2004 Jetta BEW 5spd (dual duty track car and daily driver beater)
[ QUOTE ]
I have 30,000 on a 2002 Jetta that I bought with 5000 on it 6 months ago and was thinking I might go ahead and service the transmission for peace of mind. Do you guys think this is overkill? If this mod will make that auto tranny last longer, I am all for it, and may as well do it, just thought I'd get your opinions first.

[/ QUOTE ]

30k miles is probably overkill. 50k might be more reasonable. I waited until 100k, but my fluid was dark - still ok though, didn't smell real burnt. I'm at 130k miles now and might do it again just to be safe and so I can do the line pressure mod (first high-miler?) and make sure everything's ok. My tranny's been acting funny this winter (electrical probs from water /images/graemlins/confused.gif shorting out the engine-transmission communication and throwing it into limp mode).
 

KERMA

Vendor , w/Business number
Joined
Sep 23, 2001
Location
here
TDI
99 beetle and 04 jetta
[ QUOTE ]
Has anyone tried this adjustment on higher milage transmissions?

[/ QUOTE ]

My transmission had 95k on it when I did it.

Another thing I noticed: the annoying delay shifting into gear is gone.
 
Joined
Jan 8, 2004
Location
Northern VA
I'm going to try it this weekend, I was planning a fluid/filter change anyway.
I have 107k on my CLK trans, I didn't change the fluid until 100k, smelled rather pungent and was real dark with chunks floating in it.

Couple of side questions, do any of you know if the final drive fluid interchanges with the with the ATF, or do you drain it separately?
What fluid did you all use OEM, redline, Amsoil or something else?

Anyhow I'll try it an let you know what happens /images/graemlins/smile.gif
 
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