Speedo reads high after 4.444 swap

[kimokalihi]

My speedo is way off and I believe it's due to the JDM Forester 4.444 final drive ratio transmission. Going down the freeway along with traffic in a 70 MPH zone it reads 85MPH. 60MPH on the gauge feels like 50MPH.

Is there any way to correct this? It's annoying.

[Deride]

Which speedo sensor/cable are you using?

[SLODRIVE]

The transmission swap shouldn't have affected the speedo unless the speedometer drive gears were swapped out before you installed it. I just swapped from a 3.90 to a 4.111 transmission and my speedometer reads correctly.
Tire size can throw off you speedometer - What size tires are you running?

[kimokalihi]

This was on stock tires and wheels. Actually not quite I believe the tires were 205/60/r15. Tire size shouldn't throw it off that much though right? That's a huge difference.

I'm using the stock gauges and stock speedo cable.

[evolutionmovement]

How is the speedometer supposed to know you changed gears? Sounds like it doesn't. Without doing the math, that speed difference/engine speed of 4.44 vs. the 3.9 sounds about right.

[kimokalihi]

Well I don't see what else could be affecting the speedo other than the final drive ratio difference.

[evolutionmovement]

There should be a gear setup at the end of the speedometer cable that regulates the speedometer, the ratio of which matches the final drive. You'll need the one from the 4.44 equipped car.

[Legacy777]

The speedo gear in the transmission will affect things, and it likely the speedo gears are different between the 3.9 and 4.444 transmissions.

As mentioned, tire size will throw off the speedo as well. Check out this thread with links to tire size calculators
http://bbs.legacycentral.org/viewtopic.php?f=8&t=27637

[kimokalihi]

There should be a gear setup at the end of the speedometer cable that regulates the speedometer, the ratio of which matches the final drive. You'll need the one from the 4.44 equipped car.

On the gauge side of the cable? In the cluster?

[evolutionmovement]

Transmission.

[kimokalihi]

Are you talking about the bottom section of the cable that inserts into the transmission?

[PhyrraM]

NORMALLY, If you did not change any plastic gears in the transmission when you swapped the 4.44 into your car, then the JDM transmission should have already had the proper gear installed to make the speedo read correctly.

BUT, you have a Forester transmission which uses taller tires. So you will need a plastic gear from a 4.44 transmission that is specced for "car" tires. (Legacy or Impreza). The dealer should be able to get you what you need, or possibly post up a WTB on the Impreza sites.

[ericem]

But, he needs to pull his tranny and take it apart?

[kimokalihi]

If so, hell no.

[PhyrraM]

But, he needs to pull his tranny and take it apart?

Not sure. There are two gears involved. One is around the output shaft, the other is on the end of the speedo cable and meshes with the first. If you just need to swap the speedo cable one, then you can do it with the trans in the car.

Hopefully someone more familier with the trans can help.

[kimokalihi]

I'm not sure which gear you're talking about. The end of the speedo cable just has a rectangular shaped metal piece that inserts into the transmission.

[evolutionmovement]

You may be SOL, then. Sounds like the gearing is internal. Looking at the parts catalog for the Legacy, they only show the two part numbers for all the manual transmissions and it looks like the 1 part number just superseded the other. If the speedo end contained the different gears, then there should be at least 3 part numbers (3.7, 3.9, 4.11, ?). Perhaps there's another way to alter the ratio, but I don't know.

[kimokalihi]

Well it's not a huge deal but it would be nice to know how fast I'm going. This 4.444 final drive is certainly not a freeway setup. Driving at about 50-55 mph is 3K RPM! Oh well I think the last tank of all freeway miles I got about 25mpg. Not bad for 60-70 mph the whole time and a few full pulls.

[Legacy777]

To change those gears, you have to disassemble the trans.

[macipusy]

Use the gps on your phone....if you have one like that....to see how fas you are going.

[kimokalihi]

Nope, my phone is old.