Can anyone give me an idea of my gear ratio

69-er · Jun 14, 2005

Hey Doug, read my post at the beginning of this topic to see why he needs to place one tire on the ground. I think it will clear things up.

Ray, you are doing the check correctly. 3-1/3 turns should be a 3.36 or 3.31, whatever is correct for a 12 bolt. As far as the double line burnout, a car typicaly spins the right tire because of the torque reaction that lifts the that tire, causing it to loose traction. Your burnout result does not necesarily mean you have a posi. When you are doing your gear check, if the tire you are turning turns easily with the other on the ground, you either have an open rear end or a worn out posi. A worn out posi would display the same characteristics of an open rearend.

I just thought of another possiblity. Were factory tachs available with 6 cylinder engines? If so, if your tach was calibrated for a 6 cylinder, then the extra two pulses per revolution of the engine would cause it to read high.

If you are going to pull the cover, (the best way to resolve this), there are two ways to go about it. Count the teeth of the ring and pinion and divide the ring teeth by the pinion teeth. That will be your ratio. Or, on the ring gear, you will find a series of numbers that designate the number of teeth on each gear. It's easier to show you than describe which numbers are which, but look for numbers in this range: 11, 12, 13, 14 and 40, 41, 42, 43 give or take a couple. I think they will be separated by a colon : Divide the two like you would with the tooth count to get your ratio.

Larry

69-er · Jun 14, 2005

69-er said:
Were factory tachs available with 6 cylinder engines?

I checked my White Book, only V8's with consoles had tachs. Worth a shot...

Larry

Gary L · Jun 14, 2005

DOUG G said:
This 3 1/3rd thing has me puzzled. Gears are ...say 3.55:1 ratio. This means the drive shaft would turn 3.55 times to 1 tire revolution. So your 3 1/3rd to 2 revs is looking like a 1.something? and isn't possible.

Maybe he tried it twice. 3 1/3 each time.

sicsD8 · Jun 14, 2005

Check the code on the passenger side front of the axle tube and give us the number. You may need to use a wire brush to scrape the crud off first. This code will give you your ratio and whether or not it was a factory posi. Again, your findings are indicating a 3.31 rear, not 3.55. (3.55 would be just over 3 & 1/2 turns, get it?). Try the driveshaft revolution test with both wheels off the ground and you should be getting 3 & 1/3 to 1 ratio(or 3.31).

DOUG G · Jun 14, 2005

ray moore said:
Hi Doug.

I turned the tire twice, and the revolution of the drive shaft was a little more than 3 and a forth turns. I rounded to 3 and a third turns. I did not divide by two. These were the raw numbers and one tire was on the ground. It is an open rear end.

I did ask that.

69-er , I did read and re-read your post and I agree about the one wheel on the ground. But I can't understand this 3.3 turns to 2 rev's unless Ray blinked,lol.
Also I only used 3.55's for an example, I have no clue why.

ray moore · Jun 14, 2005

I will try in the next day or so,( I have to work late tomorrow night) to.

1. Find the numbers on the front of the axle
2. Either try the try the two wheels off the ground test, or pull the rear cover off and check if I cannot find the numbers on the axle.

I appreciate everyone hanging in there on this problem with me. Not that I like problems but when one comes up it's an obsession with me to find the answer. It's like a challange , with help like this on this forum it also is kinda fun. I guess misery loves company.LOL

Thanks All,

Ray

SnakeEyes · Jun 14, 2005

Nantooch said:
Ray. lift the rearend and sit it on stands.. put the car in neutral. mark a spot on the right tire and on the driveline.. Now rotate the tire one full revolution while counting the times the drivline turns. Figure any amount of turn after the origional mark on the driveline by way of minutes on a clock. This will give you the ratio of your rearend. As for the parts to switch to a posi.. Contact BGH at gears@muhlon.com for the desired ratio and he can get the parts to you at a reasonable cost. To upgrade mine from an open to a posi with complete new internals and 30 spline axels was in the neighborhood of 750 for the parts. Your local shop will charge you accordingly for the install.

woah!!! On my Chevy truck I used to have (1990) it was an open diff, I bought the lock-right unit by power trax for less than $300, and it cost me like $75 to have it professionally installed by drivetrain experts(A massive shop, they ALL they do, here in town)....who were amazed by its performance. They said there were even going to check into becomeing a distrbutor after I introduced them to it.....it's a full locker though....They made hi0tech posi-ish systems but they cost a bit more, and also tend to replace a lot more. but if your diff is in good shap, check into Powertrax Lock right

69-er · Jun 15, 2005

DOUG G said:
I did ask that.

69-er , I did read and re-read your post and I agree about the one wheel on the ground. But I can't understand this 3.3 turns to 2 rev's unless Ray blinked,lol.
Also I only used 3.55's for an example, I have no clue why.

That's because when one wheel is on the ground, the other wheel will spin twice as fast, given the same driveshaft speed. Did you ever see a warning in a typical owner's manual about spinning one tire in the mud/snow? It will say that even though the speedometer might read 50 MPH, for instance, the spinning wheel will be going the equivalent of 100 MPH.

DOUG G · Jun 15, 2005

Read an owners manual ? Can't say I have (fully) Just small parts like "how to reset change oil light".

69-er · Jun 15, 2005

DOUG G said:
Read an owners manual ? Can't say I have (fully) Just small parts like "how to reset change oil light".

Yeah, I hear ya. I guess all they are good for is to learn about uncommon things about the car.

ray moore · Jun 25, 2005

Checked my axle code today and it is BR0708GE which shows to be a 3.07 POSI 12 bolt, which makes even less sense.

What the heck! What are the possibilities.
1. Can a Posi slip like a clutch in a transmission cauing me rev high and loose gas mileage?
2. Can my tach be WAAAY! off, Original TIC TOCH TACH, I still have a points Dist. Could I by a cheap after market tach and hook up to check Tach calibration.

3. Could my 4 speed be doing something to effect this?

What would be the next step to figure this out.

Thanks
Ray

69-er · Jun 25, 2005

That code is really meaningless, because the gears could have been changed.

A posi only slips when the car is in a turn, just like an open rear.

Using another tach for testing is an excellent idea.

Your transmission can't be affecting this situation unless your 4th gear ratio is not one to one, (unlikely), or you're not in 4th gear.

Physically checking the numbers on the ring and pinion or counting the teeth are the only way to resolve this once and for all.

Larry

ray moore · Jun 25, 2005

I'm pulling the cover off today and will post the result, need to go get a gasket and gear oil first.

Thanks
Ray

Can anyone give me an idea of my gear ratio

69-er

69-er

Gary L

sicsD8

DOUG G

ray moore

SnakeEyes

69-er

DOUG G

69-er

ray moore

69-er

ray moore

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