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Hi, novice question here, I am having my diff rebuilt by a recommended "expert" who is asking why there's no circlips on the end of the yokes he removed, apparently there was a burr on the end, am I right in thinking the ends of the yokes have worn away? And need replacing.
I should have also mentioned I am in the UK. But didn't think this was relevant as to whether the yokes were worn or not???
Your expert appears to have never worked on a C2 or C3 differential. Did he remove the differential or you did. If he did, you at the very least need to get him a shop manual. If you did, get the differential back and find someone else in the UK or the continent.
Here is a question you can ask your expert. Now that you know you need axles, what will you buy- New or Rebuilt- tipped or cored? If you just go to a website an order blindly you may be going down a second wrong road. I have explained about axles for years on various sites, I am getting tired of doing it and the quality is not, repeat, is not too good today.
All I will say is when I finish a diff, there is 005-007" endplay in axles I inspect and address. Rarely are they the type I questioned above and if so they are checked for various things. I went a different route after averaging a 50% rejection rate with the axles I purchased.
Good luck, bad work is bad work, it doesn't matter if it's in Europe, Australia, New Zealand, or the good ole USA.
I know this is going to cause trouble but, in choosing to defeat the O.E.M.'s engineering by just leaving parts out because.......................... , just be sure you truly understand the effects; as just because someone says; "it works", I often wonder how well does it "really" work?
I know this is going to cause trouble but, in choosing to defeat the O.E.M.'s engineering by just leaving parts out because.......................... , just be sure you truly understand the effects; as just because someone says; "it works", I often wonder how well does it "really" work?
Scott.
No trouble at all. It is actually a pretty simple explanation once you understand the mechanics of how bevel gears work. In essence, as torque is applied, an axial force is introduced into the “driven” gears which contain the positraction clutch plates, compressing the plates, resulting in “positive” contact and thus provision for traction to be realized.
The springs and plates apply a force, albeit lower, on the “driven” gears which is constant. As these were mass-produced assemblies, there was no way GM was going to spend the time on each unit to build to the tolerances needed to eliminate the “slop” in the gears, the springs/spring plates were a far cheaper/faster solution, albeit a band-aid.
However, one does not simply leave out the springs/plates. You need to “tune” the posi, which is essentially the process of eliminating all “slop” in the spider gears. Watch the YouTube videos from Tom’s Differentials to see the tuning process in action.
I'm sorry but I'm going to have to disagree.............somewhat.
First, I understand the deflective driving force created in the function of bevel gear sets; and that this, as it turns out compressive loading of the clutch packs, varies proportionally to the load being applied in order for the attempted rotation of the gear set. But this is the catch, if the force being required to cause rotation of the gear set is low, so is the loading of the clutches, and hence the greater likelihood of insufficient load being applied for the "posi" function to succeed as intended.
The main purpose of the spring here is not solely as a band-aid for poor manufacturing tolerances, if this were so then why don't the "open' (non-posi) carrier units have them? The main purpose is as these springs as are often defined: "pre-load" springs, and that is defined as a clamping load being provided by the spring pressures which initiate the resistance in the slipping of the clutch packs; this then being over-ridden by the greater compressive load being applied by the deflective force emanating from the bevel gears in their attempt to turn in relation to one another.
Picture this: your vehicle is sitting a rest, you mash-the-gas, the initial movement of the drive-shaft, setting into motion the pinion gear, drivetrain lash taken up as the ring gear is rotated, resistance is met as the mass of the vehicle resists being set into motion, drivetrain loads increase, tension begins testing the coefficient of friction between the tire and the pavement, and this might not be so great if the surface is slippery under if only one tire, then this is the critical moment as the bevel gears may not be experiencing any significant load or differential in motion driving them away from one another so their deflective loading of the clutch packs are not so great, this is where the "pre-load" spring provide assistance as though not of the capacity needed as the engine torque climbs, it's there to initiate a resistance to break one tire loose early, as as soon as that happens the force on the clutch packs drops and all is lost, and all you got is a "one-wheel-peel"!
The next problem is that unlike the "open" differential the clutch packs behind the side gears in these wear, and this causes the side gears' location to move outward and away from the pinion/spider gears increasing lash clearances and causing positioning problems in the gear teeth relationships (wander) and in the housing bores. If a measured lash value of "X" is desired, how is this going to be maintained over time of usage? With the spring pack in place the side gear is forced to maintain a more constant positioning reducing unaccounted for movement. This for example particularly if unloaded the gears they may move off the thrust surfaces into one another, then this having to be taken up when torque is reapplied, aka. "clunk-clunk"; and this result increases the hammering effect on the gear sets increasing potential failures here. Then also though less of a concern is that as the clutch packs become unloaded the space between becomes flooded with excessive oil, that now must be displaced in order for them to provide the "positive contact" ("lock-up") desired, and this takes time and creates a potential delay in the function, and remember that if one tire starts to spin then rarely does this system have the ability to stop it.
As far as for "tuning" the gear sets' clearances, though one does want "proper" relationships for proper functional results including survivability, but as soon as there is something other than a preload value between the gears on install, this provides no substitution for the spring function; and crowding gear set engagement otherwise is not a good practice. And again, how are you going to maintain this value if so critical in the intention of elimination of the spring engineering this as the clutch packs wear. Why not set ("tune") your clearances "tight" as you might like, but then still utilize the springs? Of course, if you don't ever test the capability of the "posi" I guess wear isn't a concern, or even if it's working properly?
Also, though I have been made aware of opinions on why elsewhere, over the decades, I haven;t actually heard the benefits in this discussion for why one is leaving them out yet? And I don't think: "because ya' just don't need 'em" is a good answer.
Some interesting points, even if they are not the common belief of the majority of people on this forum. None the less. I to have wondered what happens with these tuned posi's after wear sets in and end plays open up.
The true benefit of removing the springs?
Why is it having the springs in there is not a good thing?
And THE Most important question I have, where can we purchase replacement yokes? I replaced mine 30 years ago, and now I find one has worn.
Interesting discourse but not what I want to spend many more brain cells on. I will only add that Gary Ramadei is the current expert on how to build them. He has generously helped many of us on this forum to build our differentials using best practices and he is a proponent of tuning (which is how I build them). The late Tom Watt was a strong proponent of tuning the posi and Gary has long cited his practice of doing the same. Tom learned his craft from the legendary Pepe Estrada. Gary has built many hundreds of these and I am not aware of a single instance where someone was dissatisfied with their springless builds. Kind of hard to argue with that pedigree and success.
I doubt many people are going to say that installing the springpacks is is a bad thing so if that floats your boat, good for you. You won’t be “unliked” if you do.
Having been tutored by Gary, and tuned my own posi, and seen the results with my own eyes, there is one overwhelming effect of tuning the posi gears.
The spider gears are now in constant contact vs enormous amounts of slack in an OEM spring-pack posi. Mine must have had .100" of slop in the spiders.
That impacts an enormous shock load on the spiders when they finally hit. Sudden Shock is what breaks diff parts.
The constant contact removes the shock load.
No one really believes a 100# spring pack is going to stop 5000# of torque on the rear tires from spinning do they?
The physics says that the beveled angle of the spider gears imparts its own side loading of the clutch paks. With 1000-1500# of torque being applied to the pinion in 1st gear, and 3 or 4x that after it goes thru the ring gear, those side forces on the clutch packs thru the spiders are surely going to be an order of magnitude greater than any 100# or so force imparted by the spring packs. Hence they become completely unecessary.
The spider gears are now in constant contact vs enormous amounts of slack in an OEM spring-pack posi.
I'm not sure that "Constant contact" would be the correct vocabulary here, as unless crowding the gear set there will be "lash" or "clearance" present (as there should be); though of course a "properly" ("tuned"?) set-up unit one would attempt to reduce excessive lash sums as much as were possible, but this would have to be reviewed periodically to be maintained and compensated for as component wear takes place in service.
No one really believes a 100# spring pack is going to stop 5000# of torque on the rear tires from spinning do they?
Nope, and no one said it could or would; and as I stated: if one tire starts to run-away this system as a whole really doesn't have to capability to stop it.
The physics says that the beveled angle of the spider gears imparts its own side loading of the clutch paks. With 1000-1500# of torque being applied to the pinion in 1st gear, and 3 or 4x that after it goes thru the ring gear, those side forces on the clutch packs thru the spiders are surely going to be an order of magnitude greater than any 100# or so force imparted by the spring packs.
Yes, agreed, if..............the resultant action in the deflection of the bevel gear sets ever get the chance, but if on the initial snap of the throttle one tire immediately breaks free the torque load imparted to the drivetrain plummets, and then as stated previously it's all over.
Hence they become completely unecessary.
So, once again I must disagree here, and for the same reasons as pointed out previously. And if these "Pre-Load" springs really were "unnecessary", then why would the manufacturer, as tasked by "real" engineers, who is already being identified as practicing cost cutting measures to a degree beyond good engineering practice, have incorporated them?
C3 diff yokes
