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Discussion Starter · #1 ·
I'm troubleshooting an install problem and need an opinion about this pattern:



I know it's not right, but what is wrong about it :confused: Pinion too deep? Too shallow? Backlash is good at about 0.009"


The application is a 1978 D44HP.
 

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pinion is too shallow, bring it in a little (.004 to .005) then re-shim for backlash...

Ryan
 

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Discussion Starter · #3 ·
YeeP said:
pinion is too shallow, bring it in a little (.004 to .005) then re-shim for backlash...

Ryan
I guess I should add that what I'm trying to troubleshoot is the position of the carrier side to side in the housing. Care to take a SWAG at how far the carrier would need to be moved once the pinion depth is set?

I haven't done many of these myself, but I don't think the carrier would move more than .010 to .012 or so away from the pinion if the pinion only came in .004 to .005.

I truly am looking for third party opinon here, not trying to learn how to set up gears.
 

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If I was to take a guess I would say the pinion is shallow as well...get that correct and I suspect you MAY need to move the carrier to the driver side .005 or so.... hard to tell from the pic but did you add drag to that when you tested the pattern?

NoRM
 

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Discussion Starter · #5 · (Edited)
I tried to drag it down the best I could, which admitedly wasn't very successful. I was in a hurry to get the pattern photographed after work this afternoon before it got dark :eek: The gears are Danas and the pattern looked very good on installation until I found out there was a small burr under the inner pinion race (after it was in the truck, of course). After tightening the pinion nut, the pattern shifted to what you see now. I chose to run it this way until I get time to fix it later this winter.

So, it sounds like it would be safe to say that fixing this pattern wouldn't move the carrier over, say, .100 to .125? I'm having problems getting the locker actuator working correctly and want to eliminate gross adjustment error on the gears as a possible cause. Just working down the list of possible problems.

Thanks for the replies so far!!
 

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I would leave the pinion EXACTLY where its at and tighten up the backlash a bit!!!

danas have a tendancy to open up a bit. at .009, you certainly don't want that opening up any more....

I would tighten the backlash to .004-.005........

yeah, I know that's a touch tighter than spec.......trust me.

I'll bet the pattern improves without having to fawk with the pinion.
 

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I you seriously had a good pattern, and your pattern moved that far, then you had other problems than a burred pinion race. .009 backlash is high, but not by far... is that a Dana 44?

Ryan
 

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I think the pinion is to shallow as well. It would help to see the other side of the tooth.

You shouldn't be trying to adjust the pattern with backlash.....Set Pinion depth, set backlash, check pattern. When you move the pinion closer, that's going to tighten up your backlash a bit. Might even be perfect.

Do you have enough preload on the carrier? Looks like your marking compound was a little to thin too. Overall, from what I can see, it doesn't look that bad.
 

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Discussion Starter · #10 ·
Thanks.

As I mentioned, I'm not trying to change the pattern, just figure out how much the carrier would move if I fixed the pattern (which I will do in the next month or so.)

I'm trying to follow the setup instructions on the Electrac locker shown in the picture, but I have mechanical problems that are playing havoc with the shift fork travel (it's too deep.) I have talked with Scott at Tractech to see what could be the problem, and the first thing he wanted to check was the gear setup (he was concerned the carrier may be too close to the pinion.) From the feedback I've gotten so far, that doesn' t appear to be the problem. I didn't think it was, but I figured I'd ask some folks who look at a lot more differentials than I do what they thought about the pattern.

So, looks like I'll have to dig into things a little deeper to see where the misalignment is.

As a side note, I'm learning even more about setting up gears. Thanks to everyone for their comments!
 

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if thats a new gear then the depth is too deep subtract .004pull .005 off right side carrier and add it to the left
 

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nobody, you are looking at the pattern, and forgetting what his backlash is....

.009 is simply too sloppy.

dana axles love to open up over time, before long, that .009 will develop into .015 or near-abouts......

even though the pattern shows too shallow, its pretty close. Everyone knows that it is useless to chase for a good pattern by adjusting backlash, and deepening the pinion will cause the backlash to tighten up as well....but since his pattern looks pretty damn close, I think a simple 10 minute adjustment of the backlash only will solve the problem.....its almost 6 of one, half-dozen of another at this point....

as a personal rule, especially on dana axles, I adjust an axle so that I can pull a good pattern with spec backlash. But I will tighten up on the backlash to around .004-.005. I won't pull a pattern at this point......on my last R&P set-up I adjusted a HP dana 44 to a backlash of .0035.....after running it for about a year (trail rig only) the backlash has opened up to around .007-.008

not bad.

that's the only reason I am suggesting that he tighten up the backlash. I think starting with .009, even though it is in spec, is too sloppy. I'd rather have my gears "open up" INTO spec instead of OUT of it.
 

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Discussion Starter · #13 ·
Beezil said:

that's the only reason I am suggesting that he tighten up the backlash. I think starting with .009, even though it is in spec, is too sloppy. I'd rather have my gears "open up" INTO spec instead of OUT of it.
Actually that is what has happened here. I used these gears for a couple years in another housing before swapping them into this one. They were setup with new bearings and about .005 backlash in this housing. They have settled out to .009, that's why I'm not overly worried about it for now.
 

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be careful about excessive backlash.

under high torque loads, your contact pattern will place the maxium amount of pressure more toward the topland and heel of the tooth where it is weakest.

I've seen a handful of r&P failures, and this is where I've seen them break.

your pattern is already to close to the topland.....

wether you decide to adjust your backlash or pinion depth, obviously you realize you'd better do SOMETHING, right?

I mean, that was the purpose of you posting your pattern?

maybe you were hoping for more responces that said "yer fine, run it."

I wouldn't
 

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Discussion Starter · #15 ·
Beezil said:

wether you decide to adjust your backlash or pinion depth, obviously you realize you'd better do SOMETHING, right?

I mean, that was the purpose of you posting your pattern?

maybe you were hoping for more responces that said "yer fine, run it."

I wouldn't
No, the reason for the posting was to get a SWAG as to how far the carrier would move if I DID correct the pattern (yes, it needs to be done, but that's not my goal right now.) I'm getting exactly the responses I was expecting, as I stated above. It seems that I will move the carrier about .005 to .010, the problem I'm trying to solve would require the carrier to move around .125.

Here's the whole story:
The locker in the picture is an Electrac. I have the new cover from Tractech that incorporates the new plunger design and adjustment screw. The new plunger and screw limit the engagement depth of the shift fork. For some reason, even with everything adjusted to minimum engagement depth, the shift fork still travels too far. I talked with Scott at Tractech and his first concern was that the gears may be set up wrong; that the pinion depth was so deep that the carrier was too close to the shift mechanism. Well, the pattern is wrong, but it's not so bad that fixing the gear setup will cure the locker problem. I knew this, but needed another set of experienced eyes to confirm it. That's also why I just said "Hey, how's it look?" rather than explaining what was going on and getting a lot of feedback I didn't need yet. No need to muddy the waters ahead of time.

When I do fix the pattern problem, the differential will be torn down completely and all settings and adjustments rechecked and adjusted. I understand that backlash has no effect on pattern, I only stated what it was so people could draw a conclusion without having to ask what it was set at. For now, though, I just need to figure out why the locker isn't even close to adjusting properly. I'll post another question about that, I've gotten the info I need from this thread.

Thanks again to all that replied :D
and to beezil for the extra info :beer:
 
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