DIY Speedo Calibration

[y2khardtop]

First of all, I must say how extremely dissapointed I am with German automakers for not find speedo accuracy important. I've been through this on several BMW's, and now our TDI Jetta. Also, if this has already been covered on this site, I apologize.

**Shut everything down and remove the key**

First, you must remove the little cover under the gauge cluster. Just lower the steering wheel, grab it with both hands, and pull it towards you. You will feel like you are breaking it (I did), but it just slides out). It is attached via fabric, so just lay it down on the column..

Now, you must remove the two small torx 20 screws at the base of the gauge cluster. It is easier if you have a torx driver, as there is barely room for a screwdrive with exchangable bits (although it can be done, just tight).

Now, the entire gauge cluster slides straight out. It has an integrated connector in the back, so it can only come straight out. It is a tight fit, but it will slide out.

Now, you must separate the clear plastic cover from the cluster. This is done by depressing the 6 clips, and sliding them apart. On a BMW, this is extrememly hard (usually damage the connectors if you don't have their special tool), but it is easy on the Jetta

Now, all you have to do is rotate the needle on it's shaft a small amount. With the ignition off, the speedo motor locks itself down, so if you apply a force to the needle, it will rotate on the shaft.

I made one adjustment, then put the speedo back into the dash WITHOUT the clear cover. Just slide it straight back in. Then, I hit the road with a portable GPS. First time, I overshot a little, and my speedo was reading a little low. Second adjustment I hit it perfect, and it is within 1/2 mph at 60mph.

Now, you could pull the dash back out to install the plastic cover, but you don't need to. The plastic connectors will lock back into place just by sliding it straight over the dash.

Then put the screws back in (if you drop them, they'll fall through, so all is OK), and pop the little cover back on.

Enjoy!

 

[CADtechTDi]

Gutsy to jump in with both feet and rip the gauge cluster apart!
But points for being brave and getting a shadetree fix!

Can you post your speedo speed vs. GPS speed for 30, 40, 50, 60 mph, etc., now that the needle is reset?

I compared mine yesterday with GPS and it appears to be fairly consistent at 2 - 3.6 mph high. I'd much rather be within 1mph.

Have to think about this one though; not sure about twisting on the speedo needle - perhaps after a few shots of liquid courage...

 

[n2carz]

Do you mean with the ignition off, the needle is locked in position and you can push the needle clockwise too without the shaft moving? You say you overshot too low the first time...and you were able to move the needle higher with the ignition off? This sounds too good to be true. You da man! I will be adjusting mine (75mph indicated is 70mph actual, 44 ind. is 40mph, but odo. is exact).

Could take measurement of how far you need to move the needle, notice my needle at rest is about 2mm below the 0 mark, see in your pic yours looks to be about 4 or 5mm below the 0 mark

 

[jackbombay]

It's that easy? I've heard of people doing this to A4 Jettas, but never read of the needle locking in place, I wonder if that is true for the A4s as well?

 

[y2khardtop]

The speedo apears to be locked in both directions, and the needle simply slides down over the shaft. It is a simple compression fit, and can be turned with very little effort.

Calibrate is of course beyond what this can do, as I didn't make adjustment at various speeds. However, it is now adjusted so that it is right at the most important speed range, 55-60mph, for my wifes commute.

Our car was about 5mph off at highway speed. I had a 540bmw several years ago that was off 7mph, and that really pissed me off.

 

[shaark92]

Do you mean with the ignition off, the needle is locked in position and you can push the needle clockwise too without the shaft moving?

Carz,

Maybe I'm cornfused, but shouldn't you slip the needle counter clockwise a couple of degrees to force the speedo to indicate slower (or, in this case, ACCURATELY).

Hardtop,

Decelerating, this would put the needle on zero before the "calibration" directed it. Seems like there'd be a little "rub" there between zero & ~5 mph as the indicator is programmed to indicate.

Please keep this thread updated. If it REALLY is that simple & there's no adverse wear on the "motor" (whatever the that hootus would be called which is moving the needle) ... I'd certainly like to know.

Also ... for Climatronic equipped TDIs ... remember the diagnostic mode. The car knows how fast its going & it'll display it on the pax side thermostat w/ 19.1 shown on the driver side. Simultaneously press "ECON" & the "UP" vent director (top right). Use the driver side thermostat selector to change the code to 19, then the fan speed selector to 19.1 No GPS required.

Thanks for steppin out ... AND for posting it here!

Al

 

[y2khardtop]

thanks for catching that, as I missed it. You would turn the needle counter-clockwise if your speedo reads high (they all do I think).

It really is that simple, although I can understand your trepidation. Good news is you can do it without making ANY mods, so even if the speedo fails, you've got a warranty right? In the BMW, you have to do some damage, but I've done several of those without causing any issues.

** I forgot to note, disconnecting the dash reset my trip-ometer and clock, but obviously has no effect on odometer***

 

[n2carz]

On the clockwise, I meant in case I over corrected too low, most speedometers have a stop counterclockwise already very close to zero, but you have to go clockwise the whole scale to get to the clockwise stop - that is where you can get into trouble.

Does the battery need to be disconnected prior to removing cluster or just the key off?

 

[n2carz]

Well I went ahead and did it anyway. Piece of cake all done in 5 minutes. Now my indicated 70mph is actually 69.8mph, timed 10 different mile markers.

But, when I moved the needle counterclockwise it popped - kind of like it skipped a tooth on a plastic gear. Put it all together and it is spot on.

 

[y2khardtop]

mine didn't pop. I bet they put a drop of something on the shaft (like loc-tite), and it was that breaking free. Or just the friction of it initially breaking free.

Anyway, glad it worked for you.

 

[bondtimbond]

Couple of questions:

If you correct the speedo for 60, won't it now read low for 30? In school zones you might be going faster than the gage says right?

Does the needle now rest below zero?

If you overcorrect, do you have to go to full scale to a stop to be able to move the other direction?

 

[jackbombay]

The A4 Speedos read very close to 3 high at all speeds, it is not proportional.

 

[40X40]

The A4 Speedos read very close to 3 high at all speeds, it is not proportional.

This is an A5 car on a A5 forum...... But thanks for the input!

Bill

 

[y2khardtop]

On our car, the speedo motor is "locked" in both directions, so if you overshoot, you simply rotate back the other way. Our needle read below "zero" at zero anyway, since there isn't a mechanical stop at zero like on many cars.

I'd much rather my speedo be accurate in the 60-70mph range that at either 30 or a "zero". However, when I get a change, I'll measure it in increments from 10-70mph

 

[TAK1973]

Thanks for the great info. I performed this last weekend, and am very happy with the results. My needle kept 'popping' also, so I found it was easier to pull the speedometer needle off, set the cruise at 70 (by GPS reading), and install the needle right on the 70 mark. Just be careful, and don't wreck.

Now, 70 on the speedo is actual 70, and 30 on the speedo is 33 actual. The needle rests about 1/4" below 0 when stopped, but who cares? The incorrect reading at highway speeds was really bugging me.

 

[y2khardtop]

just a bump, as the other speedo thread seems to be pretty hot topic.

 

[Lightflyer1]

Actually of the two I like this one better. Although I won't do either right now.

Fairly simple
Speedo fairly accurate
Odo accurate
Climatronic accurate

My only concern with this one is if set for 60mph accurate, how far off is it for 20 mph school zones? You would still have to adjust for this just like you have to now the way it is.

 

[Lightflyer1]

just a bump, as the other speedo thread seems to be pretty hot topic.

Now that you have done the change, what is your speed at 20 mph indicated vs climatronic or gps?

 

[40X40]

Without a graph comparing gps/scangauge/speedo/etc. readings this
is sliding towards anecdotal instead of useful.
We really need some data, guys. Every 5 mph would be nice, all the way
to 100 if you can. Who wants a school zone ticket just so the gauge is
right at 65??

Thanks!

Bill

 

[suparag]

Speedometer vs. Actual Speed

Also ... for Climatronic equipped TDIs ... remember the diagnostic mode. The car knows how fast its going & it'll display it on the pax side thermostat w/ 19.1 shown on the driver side. Simultaneously press "ECON" & the "UP" vent director (top right). Use the driver side thermostat selector to change the code to 19, then the fan speed selector to 19.1 No GPS required.

Thanks for steppin out ... AND for posting it here!

Al

Shaark92: Thanks for the cool tip.

I tried it today and it works. Here is what I observed. Upto 40 mph, my speedometer was off by 2.5 miles. At 30 mph actual speed, indicated speed is 32.5, at 40 mph actual indicated is 43. Above 50 mph, real vs indicated is 5 mph high. I usually put my cruise on at 78 mph, but the actual speed turns out to be 73.

Suparag.

p.s. Even though post by y2khardtop says it is easy enough to do, I am hesistant to do it. By taking the dash apart I am scared to add another rattle or two.

 

[y2khardtop]

you aren't taking the dash apart. The gauge cluster is held by an electrical connector in the back, and 2 screws in the front. Nothing else is removed, and there is really no way the cluster itself can rattle imho.

I'll try and get some more data today, but you must realize every car is likely different. And in our case, yes I would rather have an accurate speedo at highway speed. No school zones anywhere on our normal driving routes.

 

[RickD]

I did mine last week,and am happy with the results.The indicated speed is "dead on" with my GARMIN 330 GPS.

I took out the instrument cluster,I was nervous,but I followed the instructions,and it was a piece of cake,easier than described.

No rattles.

If I can do it,anybody can.

When our RABBIT comes in a couple of weeks,guess what I'll be doing.

 

[buckeye96]

Rick,

What do you mean dead on? At all speeds or only above a certain speed?

 

[RickD]

I was more concerned about the highway speeds,and to that end,as long as the speedo needle is on the high side of an indicated speed mark ,the garmin agrees.

If I go to the low side of the "mark",the garmin indicated speed,also goes down.e.g. if my needle is on the "low side" of the 120k mark,garmin registers 119,if I'm on the high side of the mark,garmin registers 120.

It seem to be the same at 90,100,110,120,130.

I didn't bother checking at lower speeds yet.

 

[TAK1973]

At 20 indicated, my actual speed is 24 via GPS. I am not worried about getting a school zone ticket by making this change. I drive in school zones ~.5% of the time, and drive at around 70-80 for ~95%. I would prefer to have the accuracy up where I use it the most.

I believe this was a DIY thread on how to make a change, rather than a invite for a discussion on the pros & cons of messing with your speedometer.

 

[suparag]

A Quick Survey of sorts.

Speedometer Accuracy

Vote for your case:

Your VW

A. The speedometer is FASTER than GPS/other secondary method.
B. The speedometer is SLOWER than GPS/other seconday method.
C. The Speedometer AGREES with the GPS/other seconday method.

Suparag

 

[Lightflyer1]

I believe this was a DIY thread on how to make a change, rather than a invite for a discussion on the pros & cons of messing with your speedometer.

You are probably right. Some people want to do some fix to "fix" their speedo. But they want to know cause and effect of that change. Being that so far there are only two "fixes" available and few people have done either, it seemed appropriate to ask in this thread what the effect was due to this change.

I plan on trying this and setting to 55mph true. This should result in slightly low readings above this and slightly high readings when slow.

 

[y2khardtop]

OK, here's mine. Not in 5-mph incriments, but enough to show a trend.

Speedo Actual
30 31.5
40

 

[y2khardtop]

OK, here's mine. Not in 5-mph incriments, but enough to show a trend.

Speedo Actual
20 21.5
30 31.5
40 41.0
45 45.5
50 50.0
60 60.0

As much as my speedo was off, I could have split the difference, and gotten it within about 1.5mph across the board, but as stated above, highway speed is our primary interest.

 

[40X40]

Thank you for the data!
20 indicated ,21.5 actual is liveable for me.
20 " " " 24 " " is not.

I vote A, My speedo reads too fast. But I have a scan-guage II, so I know
my speed any time I want.
Please keep the data coming. I will eventually do this mod, but not
just yet. My hat is off to the 'Bleeding Edge Folks'!!

Bill