Pinion depth and preload , 742 case

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jcmmurray

jcmmurray

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I am having trouble achieving bearing preload. I seated my bearing races in the pinion part of the housing all the way. I also seated the large bearing on the pinion.I then started with a .010 shim for a starting point and started the smaller bearing with a press with the pinion inside of the housing. After it was started on the shaft with the press I then set my yoke on with an old nut to set the bearing preload. It took a lot of force to the point of wrecking my pinion threads. It was no where close to any preload whatsoever . It's almost like my bearing races are set to close together inside the housing to achieve any preload. With only 1 shim on the shaft I have no idea how I could have so much play in the bearings. At no point did I ever come close to seating the bearings to the race. Where did I go wrong ? Should I not be seating the races all the way in the housing ? kinda angry how this has confused me.
 
The last 742 I did took a .056" pinion depth shim. Most 489's take a .030". If you look at the selection the middle of the range is very high.
http://www.ratechmfg.com/pop_up_order 1108.htm

You will gain preload once you get the pinion depth close, because that shim moves the bearing seat on the small end closer to the big bearing.
 
Never mind. I figured it out. Didn't set my pinion depth first, missed the shims in the kit, Wont learn if you don't try I guess. Going to re thread my NFG threads to a 5/8 fine thread.
 
sorry to hear. hate wrecking stuff.
I sacrificed a new bearing (grind them down so I don't have to press them off) to get the desired preload. (the bearing is now a tool in my tool box)

Also don't forget the washer for the pinion nut. could bottom out before its tight.
 
View attachment 1714811038Ended up with .060 shims. Could have maybe taken out .005 of pinion depth but the pattern looks okay. Thanks for your help. I just saved a few hundred bucks.
 

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...........I think u better try again...............kim............



















.........Better try again....ur not even close....kim..........
 
X2, the pattern is too high on the teeth and too far out to the ends of the teeth.
Pinion needs to be deeper into it (or you will have a weak whiner :D)
 
Wreckin stuff and then fixin it is all part of the game. Good for you. Keep us posted.
 
jcmmurray said:
View attachment 1714811038Ended up with .060 shims. Could have maybe taken out .005 of pinion depth but the pattern looks okay. Thanks for your help. I just saved a few hundred bucks.
Click to expand...

..........try at least another .020 shim, like Doc says should of started close to .090...if at first u don't succeed try, try again....good luck 2 ya...kim.....
 
oldkimmer said:
..........try at least another .020 shim, like Doc says should of started close to .090...if at first u don't succeed try, try again....good luck 2 ya...kim.....
Click to expand...

The best part is that you don't hurt anything real expensive unless you run it like that.
Trying different shims is cheap training. :) (time consuming, but cheap)
 
oldkimmer said:
...........I think u better try again...............kim............



















.........Better try again....ur not even close....kim..........
Click to expand...

TrailBeast said:
X2, the pattern is too high on the teeth and too far out to the ends of the teeth.
Pinion needs to be deeper into it (or you will have a weak whiner :D)
Click to expand...


X2 The pattern is way off!


skep419 said:
sorry to hear. hate wrecking stuff.
I sacrificed a new bearing (grind them down so I don't have to press them off) to get the desired preload. (the bearing is now a tool in my tool box)

Also don't forget the washer for the pinion nut. could bottom out before its tight.
Click to expand...

I did the same thing when I put the 4.10's in the 8-1/4 in my Dakota.
 
The pinion is too far away.

Try a 0.090" shim and post a picture of the drive and coast pattern.
 
Gawd, haven't done one in thirty years... Patience ,is the secret here.
 
I will try again I guess. I'll go right to .090. Had a buddy that sets them up for oval cars tell me it was fine but I'll take your word for it. At work right now so give me a couple weeks and I'll redo it and send a pick . I have only a day to get it ready for 1/8 mile , along with about 5 hours of other stuff to do . This will add probably another 4 to that plus the hr to get it in there , obviously I slacked all winter
 
jcmmurray said:
I will try again I guess. I'll go right to .090. Had a buddy that sets them up for oval cars tell me it was fine but I'll take your word for it. At work right now so give me a couple weeks and I'll redo it and send a pick . I have only a day to get it ready for 1/8 mile , along with about 5 hours of other stuff to do . This will add probably another 4 to that plus the hr to get it in there , obviously I slacked all winter
Click to expand...

Don't let the possibility of missing a race destroy your rear end.
(That flat track buddy need supervision ) :D
 
Consult the contact pattern chart at the end of this link:

[ame]http://www.pirate4x4.com/tech/billavista/PDFs/Yukon%20Gear%20Ring%20and%20Pinion%20installation%20instructions.pdf[/ame]
 
The pattern is better, but the pinion is still too far away.

Increase the shim thickness 0.005" and post another picture.
 
Hi, just seen this post, check out what I wrote in this post, Will help you, "Diff gears - recommended brands?" C300
 
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