741 Questions

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67Dart440GT

67Dart440GT

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Hey guys, I am in the process of working on my 8 3/4. What I have is the 741 center with a sure grip. I had to change the yoke out due to broken bolts so I thought I would drive out the seal and replace. Got the pig painted and drove a new pinion seal in. I tightened the nut down and now when I rock the yoke back and forth I get a bit of a clunk on the ring gear and pinion (this is when I simulate the spin of the yoke but just move it clockwise then counter clockwise. Is this normal or is this a back lash problem? Any help would be great. Thanks!
 
I took the yoke back off and looks like the pinion bearing can rock back and forth a bit in the case??
 
67Dart440GT said:
Hey guys, I am in the process of working on my 8 3/4. What I have is the 741 center with a sure grip. I had to change the yoke out due to broken bolts so I thought I would drive out the seal and replace. Got the pig painted and drove a new pinion seal in. I tightened the nut down and now when I rock the yoke back and forth I get a bit of a clunk on the ring gear and pinion (this is when I simulate the spin of the yoke but just move it clockwise then counter clockwise. Is this normal or is this a back lash problem? Any help would be great. Thanks!
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You will have a very small amount of play. You should have .006~.0010" backlash. Any more than that and it's too loose. You need to check it with a dial indicator and adjust if necessary.

67Dart440GT said:
I took the yoke back off and looks like the pinion bearing can rock back and forth a bit in the case??
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When you torque the yoke down it should preload the pinion bearing so it can't rock back and forth. If it rocks side to side something is drastically wrong.

p.s. Last thing you should do after any/all adjustments are made is put a little loctite on the yoke retaining nut so it doesn't come loose.
 
Fishy is right on the money as usual. I would pull the 3rd member and check wear pattern and preload, because you have issues if you have movement in the pinion. You should have a little bit of backlash, but the only way to check it is to pull the 3rd member. So all you did was remove the yoke and change the seal?
 
Yup, all I did was pull the yoke and remove the seal. When the nut is tight you can rock the ring gear back and forth and feel the yoke move in and out a little. I put a dial indicator on it and getting in the .0010 - .0017 range. Feels too loose to me. How is this adjusted?
 
Fishy is correct about the amount of backlash, but you cannot measure backlash through the pinion yoke. It has to be measured directly off the ring gear or it will not be accurate. AT ALL. What it sounds like is you need to tighten down the pinion nut more. It sounds like the pinion is "unscrewing" away from the ring gear due to excess slop from the yoke not being tightened down all the way. But that's only a guess since I ain't standin next to it.
 
I did measure it off the ring gear. I just could feel the yoke moving in and out and seemed excessive to me. Also it was hard to get an accurate measurement because I couldn't get my dial to mount secure to the case.
 
If you know this 3rd member worked correctly before you replaced the yoke and seal I'd try to figure out what happened because by your description of the yoke rocking back and forth it sounds like something happened in that area. If you figure out what happened there the backlash might come into spec. Pull the yoke back off again and check closely for burrs on the splines of the yoke and pinion gear that may be causing it to not seat against the front pinion bearing and de-bur as necessary and re-assemble and see if the side to side movement is remedied and take another backlash reading.

If you don't know for sure this 3rd member worked right it's possible the pinion bearing preload and/or backlash was never set right to begin with.

There should be zero in and out movement of the pinion gear and you have to figure out a way to mount the dial indicator to get a accurate reading. If it's a magnetic base setup you can probably unscrew the magnetic base and bolt the indicator directly to the 3rd member case. That's how I do it and it works for me.
 
Right. I was thinkin we was on the same page.
 
Thanks, I did pull the yoke back off. I noticed that the pinion will fall down into the case a little bit. And then you can rock it back and forth a little too. The back and forth (side to side) goes away when the nut is tight on the yoke. I don't know the condition of the center as it was a used part. The seal looks to have a small gap almost as if it won't drive all the way into the case. The lip on the seal between the seal and the case has about an 1/8 inch gap. Is that seal supposed to drive all the way down?
 
67Dart440GT said:
Thanks, I did pull the yoke back off. I noticed that the pinion will fall down into the case a little bit. And then you can rock it back and forth a little too. The back and forth (side to side) goes away when the nut is tight on the yoke.
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That's good. What about the rotational slop? Is that gone when you tighten the nut down as well? It should be.

67Dart440GT said:
I don't know the condition of the center as it was a used part. The seal looks to have a small gap almost as if it won't drive all the way into the case. The lip on the seal between the seal and the case has about an 1/8 inch gap. Is that seal supposed to drive all the way down?
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Normally, yes. But I wouldn't pound snot out of it. As long as you coated the outside of the of the seal housing with sillykone and it pressed into the case an appreciable amount, you're ok.
 
I put a little bit of lube on it when I drove it in. It feels seated because if I hit it any harder it starts to bend the lip a little so I stopped hitting it haha. And yes the slop side to side or rotational goes away when its tight. I am gonna pull it back off clean it up better, take a few pictures and try to mount the dial better. THANKS FOR THE HELP GUYS! I have to get this baby figured out quick to get the car mobile again as I am moving at the end of the month.
 
67Dart440GT said:
I put a little bit of lube on it when I drove it in. It feels seated because if I hit it any harder it starts to bend the lip a little so I stopped hitting it haha. And yes the slop side to side or rotational goes away when its tight. I am gonna pull it back off clean it up better, take a few pictures and try to mount the dial better. THANKS FOR THE HELP GUYS! I have to get this baby figured out quick to get the car mobile again as I am moving at the end of the month.
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Alright. You need to take that seal back out, clean it up and coat it with sillykone on the outside of the metal housing where it presses into the case or it WILL leak there. Also, before you reinstall that yoke for the last time,you need to coat the inside splines with sillykone good all the way around because rear end lube WILL migrate up the splines and leak out the center of the yoke. If you don't do those two things, you WILL have a leak back there. Sounds to me like all is well with the clearances though. Also, you do know there needs to be a little preload on those pinion bearings when you tighten that yoke, right? Just a little resistance, not too much.
 
Here is what I am getting now. Thanks for the good tip on the mounting of the dial. I have not checked the pre load yet... any idea on what it should be? 15 inch pounds?
 

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P.S. Thanks for the tip on the silicone. I will probably destroy the seal getting it out as I don't have a good tool to do it.
 
Well the plus there is that seals are cheap. I would go maybe 20-25 IN LB. But no more. That's only about 2 LB FT. Also I forgot to mention when you assemble it for the final time, lube the rubber seal up so the yoke will slip in good. Oh and you got the dial indicator just right, BUT, you need less than .010". I would go between .005" and .008". Easy enough to change.
 
67Dart440GT said:
Here is what I am getting now. Thanks for the good tip on the mounting of the dial. I have not checked the pre load yet... any idea on what it should be? 15 inch pounds?
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10-15 inch lbs. for used bearings is about right. If the seal is in place it skews the reading so I always do it with the seal out. Looks like you have about .012" backlash. That's a little looser than I like to see it but the gear mesh pattern determines exactly what it should be. Do you have any marking compound to check the pattern?
 
Ok guys, I checked the preload with my inch pound torque wrench. It wouldn't click at 20 lowest mine goes, so I put a breaker bar on and snugged it about 1/8 of a turn. Now when I check the back lash its about .006. I don't have have any marking compound but I can pick some up and give it a shot. Can you give me some advice on how to use it? So I guess I will order a new seal, check it again without the seal, siliconize the stuff and maybe it will work! LOOKS LIKE I OWE YOU GUYS SOME BEER :)
 
Well, I've seen people do it without the seal and not have any trouble, but the spec is given considering the seal being in place because the spec is given in an as assembled condition, so I always include the assembly as a whole when I measure bearing preload whether with a new or old bearing. Just food for thought. Sounds like from everything you've said, it's in pretty good shape. ...oh and as for beer, I like anything you cannot see through.
 
How about this? My brother and I making our first home brew :) Man that smells good in the house.
 

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I guess it depend on what you read because my manual says to check it without the seal in place. Then install the seal. But I have also read that if you do it with the seal in place 20-25 is about right for used bearings. I just never did it that way because it seems to me that seals made by different companies may have more or less drag and depending on what lube (if any) is used on the seal that can affect it too. Just my thoughts.

67Dart you need to have the nut torqued down to take the preload reading and a click type torque wrench won't give you a proper reading. You need a beam type or my favorite is a dial type torque wrench to read the rotating torque. I just like the dial type cause it's easier to read.
 
fishy68 said:
I guess it depend on what you read because my manual says to check it without the seal in place. Then install the seal. But I have also read that if you do it with the seal in place 20-25 is about right for used bearings. I just never did it that way because it seems to me that seals made by different companies may have more or less drag and depending on what lube (if any) is used on the seal that can affect it too. Just my thoughts.

67Dart you need to have the nut torqued down to take the preload reading and a click type torque wrench won't give you a proper reading. You need a beam type or my favorite is a dial type torque wrench to read the rotating torque. I just like the dial type cause it's easier to read.
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Really? I've never seen a manual that said that before. While we've been discussing this, I looked in my Chrysler 1963 service manual and it shows the measurement being taken as a whole assembly. Oh well, I'm sure if the lack of seal is compensated for, it'll be right.
 
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