AXLE CODES:

[Stewart G Griffin]

Can we discuss axle codes?

14066261   This was on the driver's side tube.

83 C-10 2WD.

I just want to know what gear ratio i got.

[Blazin]

Best way is to pull the cover and divide the last two numbers into each other or count the teeth and divide them if no numbers on the ring gear. 83 C 10 most common were 3:08 or 3:42.

[Stewart G Griffin]

I don't really want to pull the cover.

I'm thinking it's a 3:08 by feel;  Truck has little to no bottom end pull.

And the same token, it's merely loafing at 55-65.
The pedal is barely being pressed at that speed.

Any other ways?

Charts?

[VileZambonie]

The only real way is to pull the cover like stated. Another backyard job is to mark the driveshaft and one tire. Block the other tire and count the # of shaft rotations to one tire roatation but if you're going to go through all of that crap just pull the cover it's the only real way to tell what's inside.

[Stewart G Griffin]

Quote:Did these trucks (83 C-10 2WD) ever come with 2.56 rears?

Because according to my observations (jacked one wheel up and the driveshaft turned about 2 1/2 times per exactly two tire rotations) this is what i got.

Yes they did.

And the spinning tire trick is only a guess.  It could be 3.08 which is the most common.  The only way to tell is to pull the cover, and with the truck being over 20 years old it wouldn't be a bad idea to put new oil in it...

Edited by: roundedline at: 10/2/06 3:01 pm

[Stewart G Griffin]

PT.2, CONTINUED ETC.

(i am slowly, but surely trying to get the truck back to normal---it runs ok, but there are little "issues" that need to be addressed.  i am doing this while juggling 3 jobs and other responsibilities, hence the slow replies)

Let's say i do pull the cover;

1) Will i be able to see all the teeth on the ring and pinion or will i need to still rotate one (or both) of the tires?

2)i'm assuming there is a gasket involved?  If so, where to get a new one?

3) Where to get gear oil.  i want to keep things stock for now.  Also, how to check the level?

4) What torque should the 10 bolts be torqued to?  (it's a 10 bolt rear.  That much i do know)

The reason why i have to do this is to determine the rear gear because my speedo is not reading correct.  Plus, it would be nice to know what gear i have.  Actually, isn't this printed on the build sheet?

[kawliga1978]

You can get gear oil at the local auto parts as well as the gasket. If the gasket is not available a tube of RTV will work fine. You will not be able to see all of the teeth at the same time. In a rear end shop they have a marking compound that is about the same as shoe polish, only white or yellow. Mark a tooth on the ring gear and spin one tire, write this number down. Mark a tooth on the pinion gear and spin the tire again. write this number down. Divide the smaller number into the bigger number, this will be your ratio.

Note: This has to be done with the transmission in neutral so the driveshaft can spin. 

[Stewart G Griffin]

1) So can i use shoe polish or white out?

2) Does it matter which wheel i jack up?  (this is a non-posi unit as far as i know)

[VileZambonie]

If you pull the cover off and look at the side of the ring gear the # of teeth will be stamped on it. Example 41 : 11 = 41 ring gear 11 pinion. Driven over drive will give you your ratio.

[Captkaos]

1) Will i be able to see all the teeth on the ring and pinion or will i need to still rotate one (or both) of the tires?

Can't see the pinion, only the ring gear...  roll it over till you find the stamping (see Vile's post above)

2)i'm assuming there is a gasket involved?  If so, where to get a new one?

Any parts store will have a gasket.  Autozone, O'Rielly's, Napa....

3) Where to get gear oil.  i want to keep things stock for now.  Also, how to check the level?

Get the oil from the same place you got the gasket.  Use 80-90wt gear oil.  To check the level you need to pull the cover, get the numbers off, put the gasket back on and bolt on the cover.  The pull the plug out of the side to fill it.  Once it get level with the hole, it is full.  Get 2 bottles as I think it holds a more than one.

4) What torque should the 10 bolts be torqued to?  (it's a 10 bolt rear.  That much i do know)

tight.  I have never torqued them, I just get the good and snug.

Actually, isn't this printed on the build sheet?

If you have a standard ratio and 83 will have 2.56 gear most likely and it will just show standard on the build sheet.

[Stewart G Griffin]

Soooo.........

i guess it does not matter which side wheel i jack up?

[VileZambonie]

jack up either side. 20 lb-ft on the meatball cover bolts.

[Stewart G Griffin]

OK, just checking----when i see the #stamped on the side, that's good enough?  Or do i also need to count the teeth on the pinion?

[Captkaos]

You only want to find the numbers stamped on the ring gear,  it tells you the numbers on the ring gear and pinion.  You can't see the pinion well enough to count the teeth...

[Stewart G Griffin]

Alright, it turns out that i do have the 2.56 gear and, also, there is a blue and white decal on the driver's side inner fenderwell entitled SERVICE PARTS IDENTIFICATION and on this decal there is an RPO code GQ 1----Rear axle standard.

Also on the decal, it lists 195/75R 15's  as the standard tire, although i have 235/75R 15's on the truck now.  But that's close enough?  (about 28 inches diameter)

1) My speedometer reads about 10mph less than actual speed----it takes 55 seconds to do a mile(so 65mph) with the speedo at 55mph measured by mile markers.  With the speedo at 45mph, it's a little closer---48 miles per hour taking 73 seconds to do it.

So, offhand, does anyone know which speedo gear combinations----drive gear off the output shaft of the transmission and driven gear (driven by the drive gear) are correct considering i've got the 2.56 rear gear and 28 inch tires?  Also, the trans is a TH-350C.

2) i will still do research ,including the inevitable taking the output shaft cone off the transmission to see exactly what i got, but i wanted to check if anyone knew first.
My theory is that the transmission in the truck got replaced somewhere along the line with one that came out of another truck or car with lower rear diff gears----this is why my speedo is reading lower than actual speed.