Am I over thinking this?

[mrk5]

For the longest time I thought I had 3.73 rearend gears. But I've since found out CUCV blazers came with 3.08s. I started checking things out, used the calculator on Randy's and what matches up perfect with my RPMs at various speeds is 3.42s in the rearend. This is true even with the tranny in 2nd. The only thing I haven't done is pull the cover and count teeth.

Here's what's occupying my mind. Could it be that my blazer actually came with 3.42s.

Or is my tranny slipping that bad? The only other thing I've noticed is that when the tranny is good and warm, I have to give the motor some throttle to get it moving in reverse. When you first pop it in gear, it is just like it's still in neutral. I've been keeping an eye on the fluid and it is nice and red. I know that reverse and direct drive share clutch packs.

Basically I can either drop $1000 on the tranny or new gears on the axles. What are the opinions.

 

[SlyDog]

Well...To put all doubts aside pull the cover and count the teeth! Then come back and go from there. You don't want to make too many assumptions if you aren't sure what the problem is to begin with /forums/images/graemlins/thumb.gif

 

[mrk5]

Yeah I know. But I work fulltime and then 3hrs of class /forums/images/graemlins/frown.gif. With this being 4th of July weekend, I'm looking at two weeks before I'll have time to do it.

The wondering is just about killing me /forums/images/graemlins/screwy.gif, so I just had to get it off my chest.

I'm mostly curious if the 3.08s in M1009 is set in stone or if there were variations.

 

[spearchucker]

Have someone drive it real slow and count the driveshaft rotation and number of tire rotations. Then divide # of tire rotations into # of driveshaft rotations.

 

[82diesel]

Or you can jack up the passenger rear tire and rotate it by hand one full turn while counting the turns of the driveshaft.
Mark the drive shaft with white out or something similar to get exact.
Then times that by 2.

1 1/2 rotation is 3.08
1 3/4 rotation is 3.42

 

[pauly383]

[ QUOTE ]
I'm mostly curious if the 3.08s in M1009 is set in stone or if there were variations.

[/ QUOTE ]

Assembly line waited for nothing. If they were a day or two away from delivery and all they had was 3.42's , it got 3.42's . That one of the reasons we see some weird non-COPO combos out there.

Wait until you have 1 hour free and drain the fluid , read the numbers on the side of ring gear , and seal her back up /forums/images/graemlins/k5.gif

 

[POWERMAD]

Unless it has a spool or welded spiders you have to rotate the tire 2 times.
A spooled diff takes one rotation of the tire and has to have both wheels off the ground.
If the wheel can be rotated with only one wheel in the air then you spin it 2 times.
Make reference marks on the wheel and yoke, rotate the tire twice and note the revolutions on the yoke.
2 people kinda help, 3 and a bit=3:08, almost 3 and a half=3:42, 3 and almost 3/4= 3:73, 4 and a bit is 4:09/4:10 and so on.
Chock the front wheels, raise a wheel and give it a spin.

 

[84_Chevy_K10]

I would say it has 3.08s. The reason you think that it has 3.42s per the chart is that it has a TH 400 which has a noon-lockup torque converter.

1009s have 3.08s.

 

[diesel4me]

There should be an axle code on the drivers side axle tube--I have found only one in the spot the factory book tells you to look for it--many I looked for were either not stamped at all,or somewhere I couldnt see it,or it rusted off--I think its quicker and more reliable to pull the cover.You probably need new gear oil anyway!. /forums/images/graemlins/crazy.gif

 

[mrk5]

You're right on the gear oil. I've only ever checked the level.

I have tried rolling the truck and counting rotations and came up with 3.

I haven't done the jacking one side up yet.

I appreciate all the comments. I'm just going to have to wait until I can pull the cover I guess. Course I'm tempted to not even worry about and just put 4.10s in the D44 and 12b I have sitting around and be done with it. I think I would really be smiling with 4.10s.

But at least I can feel better getting all these musings off my chest. /forums/images/graemlins/smirk.gif