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ring and pinion play???

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by RESTORE89, May 15, 2002.

  1. RESTORE89

    RESTORE89 1/2 ton status

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    when shifting from park to drive or reverse how far should my driveshaft rotate before the gears engage and prevent further movement?????
    thanks
     
  2. bigmack

    bigmack 1/2 ton status

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    It really shouldn't rotate any. If it does, your ring gear & pinion gear are not set right, or they may be wore out, or you may have a bad pinion bearing, and there may be other posibilities. The ones I have had over the years that had what I would call excessive play didn't last very long. Alot of diff's will have a little play and run for a long time.
     
  3. txbartman

    txbartman 1/2 ton status

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    You should have some play, but not much. Hard to describe what would be acceptable. Too much play could also be associated with a bad u-joint.
     
  4. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Well some play is normal. If you have a locker like a Detroit or a Lock right there will be more. The proper way to check is to measure the back lash off the ring gear. Should be something like 5-8 thousandths. Now the lower the gear (higher the number) the more play you will have on the pinion. On my truck with a 4.10 gear and a Detroit I get a good 1/4 turn. on my wifes truck with 3.73's and a Gov lock there is about 1/8-3/16ths. Some of that play is not the Ring and pinnion it s the slop in the diff. Both axles check out fine when the back lash on the ring gear is checked. THere has to be some to give room for the gears to expand as they heat. You will have less play after comming off the hwy in the middle of august then you will first thing in the morning in January. If they made it so tight that there was no slop it would over heat and eat it self up.
     
  5. RESTORE89

    RESTORE89 1/2 ton status

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    i have 4.10 and a lockrite, and from neutral to drive or reverse i also get about a 1/4 turn
     
  6. Oblin Goblin

    Oblin Goblin 1/2 ton status

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    How much up and down movment in the yoke is acceptable if you grab hold of it and move it up and down?
     
  7. txbartman

    txbartman 1/2 ton status

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    Play in the rotation of the driveshaft is one thing, but movement of the yoke?!? Bad thing. I assume you are talking about the yoke into the diff? This is attached to your pinion gear. THERE SHOULD BE NO IN-OUT or UP-DOWN PLAY IN THE YOKE! If you have some, either your gear is in SAD shape or your pinion bearing is SHOT. Either way, you are in serious trouble. Get that addressed before you blow your u-joint going down the highway or grenade your gears.
     
  8. Oblin Goblin

    Oblin Goblin 1/2 ton status

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    Is it really that bad? Its been that way for at least 2 years now. It doesn't move alot but I can wobble it around with the tranny out of gear. Maybe a millimeter or two of travel. A transmission shop I took it to said it wasn't good but the rear end would start making noise before it blew up. That was 2 years ago, still no noise. Maybe I'm pushing my luck.
     
  9. BlueOx

    BlueOx 1/2 ton status

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    RESTORE89, mine has the same problem I think. I have even layed under the K5 while someone shifts gears. I have talked to many people about the problem and have had no luck. With my foot on the brake and me going from PARK to DRIVE or REVERSE the truck lunges forward/backward real bad with a loud bang. Does yours do the same thing? I really need to fix mine...it drives me crazy.
     
  10. Z3PR

    Z3PR Banned

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    Mine does that. I'm very seriously consittering saying to hell with the 12 bolt, on just swap in a 14 bolt FF.
     
  11. txbartman

    txbartman 1/2 ton status

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    Picture in your mind how the two gears (pinion and ring gear) mesh together. Now also understand that R&Ps are helix gears. That means that the teeth aren't straight, they have some curve to them. So, it is imperative that they mesh correctly. There should be some play as the gears mesh simply because the gears do expand and contract as they get hot or cool down. That play is called backlash. It can't be too much or the power from the motor will strip out the gears, break off some teeth, or other bad things. It can't be too tight or the gears will chew themselves up as they get hopt and try to expand.

    The pinion gear has a gear on one end and splines and thread on the other end. The end with the splines and the thread is where your yoke in the diff attaches. It slides up on the splines and then a pinion nut goes on the end holding it sandwicjed together. The pinion itself sits in two bearings (kinda like wheel bearings). One bearing is on the inside of the diff housing while the other is behind the yoke on the "outside" of the housing. Any kind of in-out movement or up-down movement of the yoke indicates that the pinion is moving as well on the gear end. Any movement will make the gear mesh incorrect. And, to give you an idea how close the tolerances on this stuff are, the backlash is measured in THOUSANDS of an inch. Acceptable backlash is commonly between 8 and 10 THOUSANDTHS of an inch. So, a millimeter or two of movement could be huge (potentially) compared to the normal backlash.

    As far as making noise, the rear end may or may not make noise before it goes. For example, if you problem is one of the pinion bearings (as I expect) and suddenly the bearing goes, think how fast all that is turning. If the bearing were to freeze, you probably would here a lot of noise and notice a difference in the power characteristics. on the other hand, if it were to destroy itself causing the pinion to loose support, the gear teeth would immediately have serious meshing problems and probably chunk each other apart. Such devastation in the diff would probably have other major impacts like on your spider gears and potetntially your axle shafts. The carnage could even go as far as to grenade the whole thing and damage your c-clips on the end of your axles. That would cause your wheels to depart your vehicle. So, would it make noise? Sure. All at once.

    Even if none of this were to occur, movement like this is likely to cause some vibrations. Vibrations in that part of the driveline can be very damaging to u-joints. If your lower u-joint were to let go (assuming you have an NP208 tcase), that means you would drop the entire driveshaft. Again, not a preferred result.

    How soon will it blow? Who knows. Could it last you another two years without a problem? Certainly could. But, I would highly recommend having it looked at or consider this as an opportunity to start planning your axle swap!
     
  12. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    ZERO up and down should be perceptible by hand on the pinion. The pinnion rides on a pair of tapered roller bearings just like a front hub. That is set by the pre load on the crush sleeve. To test that you need a dial type inlb torque wrench and with the ring gear out you should measure about 14 inlb of rotation resistance on used bearings. about 22 on new bearing at set up. That is not much drag at all but it should remove any perceptable up and down movement on the yoke end of the pinion out. If there is up and down movement that means it's changing the angle that the pinion is running on the ring gear and can cause the R&P to be damaged.
    Don't take those figures as gospil. I'm just putting down what I remember from setting up my axle about a year ago. Look them up if your going to check them. They are listed in both Chiltons and Haynes.
     
  13. HarryH3

    HarryH3 1 ton status Author

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    Since you have 4.10's and a Lock-Rite, 1/4-turn of slop isn't excessive.

    Here's a pointer to the most complete article on the subject of lockers that I've ever read. It will explain more about lockers than you ever wanted to know. /forums/images/icons/wink.gif This is a copy of the orginal document, and it is formatted very poorly as compared to the original, but it's the only copy I can find online these days.

    http://www.darksiderz.co.uk/technical/lockers/

    Accoring to the article, a Lock-Rite with 4.10's will allow 86 degrees of rotation at the yoke between the drive and coast side.
     
  14. HarryH3

    HarryH3 1 ton status Author

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    Oh yeah, I would agree with all of the others here that have stated that the pinion shaft should most definitely NOT move up and down! /forums/images/icons/shocked.gif When properly installed, that shaft should only rotate. Any up and down or in and out movement means that the pinion bearing preload is not anywhere close to being correct.
     

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