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speedometer / odometer fix for taller tire?


impoutback 97
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I haven't opened any transmissions and was wondering if the speedometer Gear inside the transmission interchangeable? I have 27" tires now and would like to keep the odometer functional. My final drive ratio is 3.90 in a '97 5MT trans

I'm thinking if I swap the stock gear with one out of a Toyota or Nissan truck, it might work.

Am I even on the right track?

Edited by impoutback 97
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I'm not entirely how changing speedometer gears works in other cars....

 

But, I don't see how it could work with the subaru one. Any change in size will effect how it meshes with the output shaft.

 

 

 

Also, you have to completely tear open the transmission to get to it. If you've got a reason to be in there, it's easy, but a ton of labor just to swap your speedo gear.

 

 

 

I'm not saying it wouldn't be worth looking into, or that you might not be on the right track. BUT, AFAIK it has not been done or documented at all, and IMO not worth it.

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Also, you have to completely tear open the transmission to get to it. If you've got a reason to be in there, it's easy, but a ton of labor just to swap your speedo gear.

 

Better would be to swap the diff ratio to 4.11 and run a forester speedo gear, this would be your closest factory speedo option as far as I know.

 

just use a gps. they are cheap these days. the speedo function seems to be very accurate on mine.

 

Or do this ^

 

Cheers

 

Bennie

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Do you have more info about that? ... I'll Like to Fix that on my BumbleBeast, it Reads Low since the 2" Lift + 15" Rims swap.

 

I'm not sure if we're talking about mechanical or electronic systems... but for the mechanical systems, they make little boxes that have a small set of gears in them that change the output speed. You just hook them up inline with your current speedometer cable.

 

Here's one example:

RatioAdapter.jpg

http://www.transmissioncenter.net/speedometer_calibration_______va.htm

 

To find them, try doing search for "speedometer ratio adapter". You should get quite a few results, including the electronic type. icon14.gif

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Those little in-line adapters are pretty nifty, but a bit spendy for the average Subaruer. Might be able to make one yourself somehow. I know some old mechanical cruise control setups had a pair of input and output speedo cable couplings with a couple gears inside. Would just be a matter of changing the gearing, or doing something belt-driven.

 

Although my solution, when I get around to it, is that since I was gonna make some white gauges anyway, I was gonna just redraw the speeds on the dial. :D

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i used my gps for the first couple weeks after the larger tires. noting what speed i was going on my speedometer vs my gps.

 

when my speedo says 65mph, im actually going 74-75 mph. 55mph is about 63, etc.

 

under 40 it doesnt really matter as its only a few mph off. which isnt going to cause my any trouble around here

 

i found i got used to it pretty quick.

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I plan on going with a ratio box. Although gps sounds like it would work well Id rather have my speedo read correctly since its already there in my face;)

I havnt checked into the costs yet as im aways from having the wagon on the road, but if it saves me from getting a speeding ticket I guess it would be worth it.

Heres where I will probably end up going to, custom cable, speedo dyno and ratio box services

http://www.tacomaspeedometer.com

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Wow. thanks for all the info.

I was debating the 4.11 swap. have to cut the main shaft and weld on the 4.11 gear/shaft, here in the states. we don't have 4.11 d/r.

The ratio conversion part looks awesome, anyone try one out on a subaru yet?

Do the tribeca s use the tallest tire for a subaru, or is it the same as a forrester ?

i run out of gas around 225 miles instead of 325 miles @ stock tire size. really i just want to be accurate just for oil change mileage and odometer reading correct.

I've seen an instrument panel manufacturer on 4x4 tv that prints replacement panels. can't remember who the company was but Im sure it can be googled.

 

Thanks for all the responses!

 

Also, does anyone have the link for the ea82 d/r 4.11 main shaft swap/weld? The search tool won't work on my phone

Edited by impoutback 97
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From what I've been researching, a 4.11 from a 90-94 Legacy will probably bolt right up, but a 4.44 will require the radius to be trimmed down a bit to fit.

 

I'd love to rock a 4.44, and if I can find the gears I'll hafta look into having a machine shop turn it for me, but in the mean time I'm gonna look for a 4.11.

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