Pinion Depth

cumins01 said:
Thanks for the input Jesse. With R&P installed or just pinion?
Click to expand...

r&p installed but no axles yet is when I check it. I also run a girdle on the rear. I suppose a housing could get tweaked but they take a lot of abuse. My last r&p failure tried to push broken teeth out the bottom of the housing (it swelled the casting and put spider cracks in the bottom)

Dana gears did not last as long as US Standard for me. Getting just over 10 runs out of a set now.
 
SledPuller21 said:
We run .003 lash, pinion preload just over factory specs(too tight is robbing horsepower) set shims up behind the race not the pinion bearing, and change every 10-12 passes. I ran my current one for 16 passes before it broke.
Click to expand...

I run more backlash but overall I agree with this. I do think partially it has to do with how your truck is set up and drving style too. Different backlashes will result in different shock loads depending on how you drive and how far you come out before dropping the clutch.

In the rear, billet caps and a 3/8-1/2" steel girdle with snubber bolts has worked well for me this year. I made it 8 passes before I saw a crack in the ring teeth. I started breaking front ring and pinions every 3rd pass and then I started setting up the shims behind the pinion bearing race with better results.

Also on pinions that have an oil flinger they tend to bend around the gear and loosen the pinion so if you can get some hardened shims instead thats a good idea.
 
It's a large disc that presses between the pinion, shim, and bearing. It's was dips down into the gear oil and slings it everywhere (oils the pinion bearings).
 
Don't use usa standard....... they are missing important processes.

Set the pin height with your tool to what the dana spec is then check the pattern, then make adjustments from there.
Don't run the bl as others have said, all that does is create drag, ring teeth will deflect and there will be BIND. I wouldn't even recommend doing less than .005.

Make sure you use a case spreader, learn how to use it, learn how to set the carrier preload so is DOESN'T deflect as much under load and open up the bl, which bl moves up and and down the tooth and what causes ring failures.

.
 
Ive set mine up every way possible and it doesn't really seem to matter..If you have a chassis that's hooking good, and enough motor to spin out even on the tightest of tracks, they're going to break. I can pull the cover on mine after 1 hook and there will be cracks in the pinion and the ring gear every time. I have been running them 3-4 passes and replacing them before they fail. Brand doesn't seem to matter either. We use USA Standard
 
Last edited:
Another thing most people don't realize...take a look at how many pinion teeth are in contact with the ring gear with at any given time with 4.63 and 4.88 gears. That's a lot of torque on one tooth at a time. Figure out how to get your gears numerically lower, such as t-case re-gear or pro fab 3 speed, and watch your r&p live longer.
 
It's 2 teeth at a time, and usa standard doesn't have the same processes as Dana and other quality gear companies.

Now the other issues are possibly for some here.... Are we doing a break in on new gears or just running them ?
I know many people seem to believe break in isn't important, but it actually is very important. Especially if you have a quality gear where run in was done and your set up isn't dead on perfect with their run in pattern.
Now you're running a gear in a different area it has no heat cycling , there is no run in between them and they're seeing excessive loads cold put against them.......
Another thing to do is get the diff to temp before runs... I know people don't believe in that either but, it is important and it does help greatly.

Putting them (gears) together in bind is KILLING them, there will be deflection and now you have it where they will be forced to break since there is no room either way for deflection..............
That brings me to the pinion 1 tooth on larger ratios.... there is not 1 tooth engagement at a time.... On any ratio it is never one tooth engagement... as one begins, one is center, and one is leaving always having 2 teeth on eachother together, now they're being hammered between eachother......

What happens to hardened material being hammered and pressurized ???? it cracks.

You need to really understand whats happening, it's far more than depth and backlash. There are preloads that counter deflection and tooth pattern run off which is present in every diff.

.
.
 
I have had good luck out of the USA standard gears. Eventually they will fail and it doesn't really seem to matter on brand or backlash. So I set the pinion preload around stock because there's no purpose in robbing yourself of power. My back lash in the current set is 0.004 and the last set was zero. I'm sure in about 10 hooks they will be done too.
 
Preload is extremely important.... of which what is your carrier preload. Most likely/definitely what is causing failures.

If you think tighter pin preload is robbing you of HP and .003 BL and less and running a cold diff isn't robbing you of hp... I hate to tell you, but both of those are taking your hp away.... a tighter/looser pin preload which i am also not saying to do isn't the problem.
.
However i agree that in probably 2 hooks .0 bl is going to kill the gear also
.
 
Supershafts said:
It's 2 teeth at a time, and usa standard doesn't have the same processes as Dana and other quality gear companies.

Now the other issues are possibly for some here.... Are we doing a break in on new gears or just running them ?
I know many people seem to believe break in isn't important, but it actually is very important. Especially if you have a quality gear where run in was done and your set up isn't dead on perfect with their run in pattern.
Now you're running a gear in a different area it has no heat cycling , there is no run in between them and they're seeing excessive loads cold put against them.......
Another thing to do is get the diff to temp before runs... I know people don't believe in that either but, it is important and it does help greatly.

Putting them (gears) together in bind is KILLING them, there will be deflection and now you have it where they will be forced to break since there is no room either way for deflection..............
That brings me to the pinion 1 tooth on larger ratios.... there is not 1 tooth engagement at a time.... On any ratio it is never one tooth engagement... as one begins, one is center, and one is leaving always having 2 teeth on eachother together, now they're being hammered between eachother......

What happens to hardened material being hammered and pressurized ???? it cracks.

You need to really understand whats happening, it's far more than depth and backlash. There are preloads that counter deflection and tooth pattern run off which is present in every diff.

.
.
Click to expand...

4.88s never have 2 teeth in full mesh was my point. Also you need to understand pulling trucks with filled blocks and solid suspension do not have the luxury of properly breaking in gears. But if we get a season on 2-3 r&p's at our power level ill take it.
 
Supershafts said:
Don't use usa standard....... they are missing important processes.

Set the pin height with your tool to what the dana spec is then check the pattern, then make adjustments from there.
Don't run the bl as others have said, all that does is create drag, ring teeth will deflect and there will be BIND. I wouldn't even recommend doing less than .005.

Make sure you use a case spreader, learn how to use it, learn how to set the carrier preload so is DOESN'T deflect as much under load and open up the bl, which bl moves up and and down the tooth and what causes ring failures.

.
Click to expand...

What processes are they missing?
 
I may be way off here but has anyone tried reverse rotation gears? I'm guessing they are weaker in that configuration but I'm not that familar with them.
 
How would you put break in miles on a dedicated puller?

And am I reading these right? Some guys are going through a set of gears every 1000 feet or so? How is pulling so much harder on them than drag racing with trans brake launches and better traction?
 
Last edited:
madmikeismad said:
How would you put break in miles on a dedicated puller?

And am I reading these right? Some guys are going through a set of gears every 1000 feet or so? How is pulling so much harder on them than drag racing with trans brake launches and better traction?
Click to expand...

What people don't understand is drag racers are not tugging 40k-60k pounds behind them.
 
You must log in or register to reply here.
Back
Top