What can be done to correct the speedometer after a tranny swap?

[Austin]

My '96 LSi has a '98 Forester transmission swapped in and obviously the speedometer is off by a few mph. I've been able to determine what the reading difference is but I'd like to get it back to normal if possible.

I've got a leak in my transmission that I thought was solved but isn't, and the mechanic said he'd like to get it back up on the rack and try to figure out why it's leaking still. I figured, that while he had it up there he might be able to swap out the little speedometer gear while he's in there with one for an SVX (wish I'd known about it when the swap was taking place).

My question is, would this alone be enough to get my otherwise stock SVX to read correctly ?

[Blacky]

The speed sensor must have been swapped already for the TCU to function. The SVX sensor has 3 wires and the others all have 2.
Have you checked your actual speed with GPS? You can correct by changing tire size, higher aspect ratio or wider tire with the same ratio.

[Austin]

My GPS shows +5 @ 35mph, +6 @ 45mph, and + 7.5 @ 65mph. Meaning to go a true 35mph, I have to show 40 on my speedo, to go 45 it needs to read 51, and when I'm on the highway at 65mph, my dial is reading 72-73.

[svxfiles]

Using a 4.44 instead of the 3.545 gives you a 5.5% incorrect reading. Something we (I) did not realize untill after people commented about their speedometers. sigh...
Since you have 37/31/25/25% lower ratios than stock, you can "afford" to step up to a 5.5% taller tire. Then the speedometer is as correct mechanically as it can be. If then there is still a "problem", it is a result of the speedometer innaccuracy.
What size wheels are you are running?
A225/50/16 translates to a 24.86 tall tire.
A 26.103" tall tire is 5.5% taller, fixing the mathmatical imperfection.

[huck369]

The gear that determines the Speedometer is in the transmission, so when you swap cars it is already set up for the correct gears ratio....the problem isn't the gear ratio, it is the size of the tires...the transmission Speedo drive gear is set for the gear ratio & tire size, on what it came in originally......so if it came out of a Forester, they have a much taller tire, which has a bigger circumference than the SVX tires, which makes it read fast....if the transmission came out of a Legacy GT, the tires circumference would be close to the SVX's, and make the speedo about right.

[Austin]

I supposedly have 4.44s, but I really don't know. The diff that I got to put in with the 4.44s isn't working right, so I have to keep my car in FWD mode in order to drive. (The rear end binds up and and the wheels won't move until there's a really loud metallic "CLANG!" and then the wheels will jump an inch or so and bind again until the next disturbingly loud CLANG!")

I've been told I can find out if it's actually 4.44s by opening it and counting the teeth, but I'm old and tired and don't have much free time these days.

Anyway, that's another thing for another post.

I'm running stock rims and tires. I've thought about getting RX8 rims later after I've done a ton of other stuff the car needs.

Anyway, it's not that big a deal I guess. I've got a laundry list of mechanical needs to be addressed that are way more important than the speedo. I just thought if it was something as simple as the little speedo gear that I could get that done while I'm having the tranny re-sealed.

[svxfiles]

Austin,
how about you jacking the car up in the air, properly putting jack stands for your safety, marking the rear tires and driveshaft with paint, chalk, whatever, and counting how many times the driveshaft has to rotate to get one rotation of the tires?
There are only a few rear ratios, 3.545, 4.11 and 4.44. Let us know.

[bheinen74]

Originally Posted by svxfiles

Austin,
how about you jacking the car up in the air, properly putting jack stands for your safety, marking the rear tires and driveshaft with paint, chalk, whatever, and counting how many times the driveshaft has to rotate to get one rotation of the tires?
There are only a few rear ratios, 3.545, 4.11 and 4.44. Let us know.

3.9 WAS there too how about that,

[svxfiles]

Originally Posted by bheinen74

3.9 WAS there too how about that,

You are correct. Sorry. I am and have been distracted by the reactions of others about the election result.

[svxfiles]

Wait, Austin's car is in Florida, it is an automatic transmission AND AWD. Was there a 3.9 AWD auto in this Country! Its 5:00 AM and I'm not sure.
ring, ring, Hey YT, was there a 3.9 AWD auto available for the SVX? OT you bastard its 5:00 AM! What the hell is wrong with you?!?! I am going to drive to your house and beat you to death with my little girley hands!




ok, mabey i won't call him right now. good night.

[huck369]

There were 3.70's too.....in the XT6 4EAT

[svxfiles]

Has anyone, any where ever installed an XT6 trans into an SVX?!!
Huck, don't they have/use a weaker rear end?

[huck369]

Originally Posted by svxfiles

Has anyone, any where ever installed an XT6 trans into an SVX?!!
Huck, don't they have/use a weaker rear end?

Nope, they use the same rear end design as the SVX, (160?) but have the "Outie" axle stubs....and the XT6 Trans has a different bell housing bolt pattern...BUT the front diff gears will interchange with the newer 4EAT trans of the SVX/Legacy ect.... so you could build a 3.70 4EAT set-up for a SVX

[svxfiles]

Sounds like a lot of work...
I guess if we have to, like after the apocalypse...

[scoobymal]

Just for info - UK SVX'S and JDM got 3.7 final drive as standard rom the factory. M