longhorn717

Hey everyone. Haven't had much luck getting replies on here but I thought I'd try again. Really need some expertise on my speedometer gearing. The transmission was toast and replaced but I didn't realize the gear for the speedo should be checked to see if they were the same and ended up scraping the old trans. So I need help on figuring this out. I don't know the rear ratio but I do believe it's stock. This is an 87 2wd 22r if that helps. The tires are 235/75-15. 20mph is 35. 35mph is 55. And 48mph is 70. I'll try to look and see what speedo gears I actually have today. Thanks for any help.

nothingbetter

if you know how far off it is...why change it? And lets be honest, we just travel the speed of traffic anyways.

donomite49

You can research your gear ratio and Speedo drive gear (cable drive?)and find the right one.

Or just get a stock one that came in the truck from a dealer.

Tried Google?

jbtvt

Wouldn't the pitch be different also if they were different sizes? Meaning the nylon gear would be chewed to bits in short order? Those VSSs aren't cheap.

donomite49

I would guess they would be the same pitch but different size to spin the cable faster or slower.

longhorn717

Because it's extremely annoying. And because I do pay attention to my speed. And yes it is a cable drive

jbtvt

http://www.toyotapartsoverstock.com/...340329145.html

Confirm info, but this could be yours for <$30

longhorn717

Is the stock rear end a 4.10? If so my current gear is a 35 and best I can tell my driven gear is a 6 tooth. That would mean according to the speedo gear calculator I used, I need a 17.4 rounded up? To make my speedometer spin faster I need a smaller tooth gear correct?

RJR

I think you have a bigger issue than the wrong size gearing. If your numbers are correct, the percent error is not constant with speed. 35/20=1.75. 55/35=1.57. 70/48=1.46. Beyond that, errors that big can't be explained by the wrong gear ratio and tire sizes. Even going from 4.88 to a 4.10 gearing, which is the largest stock change you can make, is only a ratio of 1.2 to 1, far less than the errors you are seeing.

I would say, since it's a cable drive, that you have a defective speedometer.

longhorn717

These speedometers aren't on a curve? I didn't think they were linear. I had read a thread where they were saying if you're consistently off by like say 5mph. It's because your needle is off. But if you're speed difference changes that it's the gearing. I'm not looking to be perfect but I could deal with 1-5 mph off. Does the speedometer drive the odometer? That's what I'm trying to fix other than making sure my speed is accurate. Makes it hard to do mileage when it's off like that.

jbtvt

Interesting, according to http://en.wikipedia.org/wiki/Speedometer that is a possibility, didn't realize they were magnet driven.

I can contribute these today before I slap the trans back into my '85 4x4. Same size?

longhorn717

Unfortunately mine is stamped 10 35. So I'll need like a 10 21 or something along those lines. Thanks though.

longhorn717

Sitting in my truck it appears the needle is sitting a little high. Like 3 mph over zero. So that will have some affect on how far I'm off.

RJR

If the gearing is off, the speed difference should change, but the ratio of actual speed to indicated speed should stay the same. For example, if it reads 30 at 20mph, it should read 60 at 40mph. If you look at my original reply again you'll see that's not the case for the numbers you gave. So, just changing your gearing (if you even could by that large of an amount) will only fix your errors at one speed. It'll still be off at other speeds.

You should check your odometer against interstate mileposts and see how far it's off. That will give you another data point to sort this out.

longhorn717

Thanks. That helps. I see what you're saying. I'll do a ten mile test tomorrow on my way to San Antonio and see what it looks like

longhorn717

So over 10 mile markers. I did 5.7 miles on my odometer. Or an error of 43% and I think some of the numbers I quoted were a bit off. Stopped by the toyota stealership and the parts guy had a hard time helping me because he wanted to use my vin to look it up. But my truck came as a four speed but is currently a five speed. The gear I have is stamped 10-35 but he said he had an 11-27 will that work or is the pitch going to be off? I don't know why toyota would make a transmission gear in 10 and 11. He wanted $40 for it but I found the same part online for 27. I just want to make sure it'll work before I try it. I don't mind trial and error to an extent but I don't want to chew up a $27 piece of plastic. Lol

scope103

according to this thread: http://forum.ih8mud.com/threads/spee...change.480939/
the first number (11 or 10) refers to the number of teeth (pitch) of the DRIVE gear. So if you "need" a 10-xx then an 11-xx requires you to replace the drive gear inside the transfer case. (Which, while a bigger job, can certainly be done. Certainly if you can change transmissions.)

longhorn717

I can change it but I didn't. And there is no t-case it's 2wd. I'm pretty sure there's a gear out there that will work. I'm just looking for a place where I can see what gears are available. I've searched and haven't had much luck

scope103

Try this:
http://www.toyotapartsoverstock.com/...348122020.html

This guy: http://www.celicasupra.com/forums/sh...350#post849350

said it was "easy" to change on a Celica, and his photo of the clip looks very similar to part 33481E for the toyota.