Speedometer **Recalibration** 1992 HELP
 

doing burnouts i blew up my Ring and Pinion.
I have 315/35/17 rear wheels
had it replaced with a 2.52 ratio (not sure if that was the correct option)
Display says I'm getting like 15mpg highway ... used to be 24-26
speedometer is off after the new ring and pinion (displaying slower)
then it progressed to flashing SYS and the speedometer became erratic. i replaced the VSS (the one without the little gear on it)
fixed the erratic numbers.

speedometer is now just off (displays slower then actual speed)
I've spoken with different mechanics. Most say its a gear issue.
I've been told I need to find the transmission output gear color. My RPO code says I have a white one but he said that doesn't make sense.

Finding this gear? How do I do it?
What would be a resolution to get my

thanks,
Zach
San Diego, CA :thumbs:l

There are only two drive gears a gray one is used with gear ratios lower in number than 3.07 the red one is used for 3.07 or higher in number.
Sounds like your original gears must have been 3.07 so the original red gear is incorrect for your 2.59 ratio.
To verify just remove the VSS and look in the hole, the drive gear is visible on the output shaft, it engages the driven gear connected to the VSS.

Who told you to get a 2.59, was it for better MPG ? Who told you it blew from doing burnouts ? :skep:

go here:

http://webpages.charter.net/khasting/util/script.html?

look under tech info:

speedometer gear calculator

enter your info

I asked them to put in the stock gears. Well when I turned asr off and did a burnout for like 45 sec I heard a crunch. Put it in gear and the tires wouldn't rotate. Had the car taken to the used dealer's transmission shop and they showed me the sheared pieces of metal

If you told them to put in "stock" gears they should have replaced them with what was in the car. If you had 3.07s and they put in 2.59s (btw, I think you meant 2.59 not 2.52) then they screwed up and gave you "highway gears" and I would take it back and demand they put the correct ratio in (unless you are happy with the 2.59s).

Not sure on a 92, but on my 88 when I went from 2.59 to 3.07 the drive gear was Red 17 tooth and Red was correct for both 2.59 and 3.07 in 88. The Driven gear for the 2.59s was an Orange 35 tooth gear and I had it replaced with a Green 42 tooth gear (which is the correct gear for a 3.07). But regardless both worked with a Red 17 tooth Drive gear. Like I said though... it may be different in 92... but I'd think it would be the same.

Either way,if your speedo is off I will bet you need to replace the Driven gear. Pull the VSS and see what you have. If it's Green (and you are gonna keep the 2.59s) then find and Orange 35 tooth and you should be fine. You will probably also have to get the correct VSS for the 2.59 geared cars.

But honestly, check to see what your original gears really were. If you are supposed to have 3.07s and they put in 2.59s... I would bitch up a storm until they put in the 3.07s!

@Jon
I have no way of knowing what was original aside from the RPO code inside the center console compartment which says D7B (36T, white) and the VSS D8K

take the vehicle speed sensor out.
its very easy - only one bolt, 10mm i think.
a tiny amount of trans fluid may come out.

let us know what color both gears are.
there is one inside that mates with the one that slides onto the vss
it will be either red or gray. that is the drive gear
the driven gear is the cone shaped one that slides onto the vss.
then we can help you find the correct ones for your setup.

You should also see either
GM1 (2.59)
GM3 (3.45)
GU2 (2.73)
G44 (3.07)

Those are the RPO codes for the various axle ratios in 92.

You are correct, my mistake. The red drive gear should work with either ratio. Hopefully he will only need to change the driven gear or better yet get them to install the right rear end.:thumbs:

I'll be having the transmission shop take a look at it this friday. I couldn't get GM to look up which gears I had stock, but if I didn't have anything like the z51 package or standard tranny I should have a 3.07 ratio ring and pinion? I'll find out what color the driven gear is as well

Post the last 8 digits of your vin!

One of the codes that jon 1all posted will be on the RPO sticker under your center console lid. Open console lid. Find code. Post here.

I have a GM1 code but that's what they put in and its been off the whole time... I'm here at the shop right now but they haven't gotten to look at it yet.

In your original post, you stated you replaced the VSS without a gear on it. Do you mean you re-used the old gear or ? All VSSs have a gear on them, although the gear is removable.

There are two gears. One on the VSS as mentioned above and one on the output shaft of the transmission. Like toptechx6 mentioned, you need to check the color of both gears and ensure they are correct for the 2.59 rear gears you had installed.

What percentage is your speedometer off? How have you verified it? Gas mileage readings on the display mean nothing.

Oh ok. The VSS I replaced because he wires were damaged, causing my erratic speedometer display. The shop pulled the vss off and the gear that it attaches to was a pale green colored 45 tooth, the gear that it matches up to was the same color. He went ahead and ordered a 35 tooth orange one. (Cone shaped gear) Does the other one inside (the cylinder shaped one) need to be replaced with an orange one as well?

the inside one should be replaced with a red 17 tooth gear

Ok, thank you.

new vss gear
 

Replaced my vss gear with a 35 tooth orange one. Speedometer is now 2-5mph off (more off at higher speeds)

Will the 17 tooth red "driven gear" make it dead on?

NO !!!! VERY UNLIKELY !! That was a "FOOLISH" suggestion in post #17!

You don't mention if it's "SLOW" OR "FAST"! Which is it? Did you calculate the error with a GPS?

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A couple of things here:

1. The 17 tooth red is not "driven" it's the drive. Difficult and expensive replacement. The VSS gear is the "driven"!

2. Your speedometer "error" is a percentage and will of course be larger numerically at higher speeds.

Options:

A 2.59 ratio in '92 MY calls for a 36 tooth "driven" and that's what it appears you confirmed with the SPID label. I would've started there rather than with the 35. Will it correct the "error"? Maybe! If your speedometer is currently "FAST" with the 35 a 36 tooth "driven" will likely accomplish a more accurate speedometer.

A 35 tooth driven in a Corvette was only used in A4's with 16" wheels.

If your speedometer is "SLOW" a 36 won't fix it but will increase the error.

It also appears that if you removed a 45 tooth driven gear from the VSS and the VSS was "correct" for a 45 tooth driven you've got an incorrect VSS for your install. Likely if you use a driven of less than 40 tooth on a VSS for 40+ tooth you will cause excessive wear to both the "drive" and "driven" gears. This means you'll be revisiting the replacement of both likely at a later date.

You "might" actually be able to confirm the VSS by electrical connector color or by a number actually stamped on it. I need to stress the "might"! If the part number is stamped it's a "for sure" - connector color "maybe"!

10456091 for less than 40 tooth counts the connector is likely white and the number stamped on it.

10456092 for 40+ tooth counts the connector is likely black and the number stamped on it.