I am by no means an expert on this but when i read your pos tthe first thing i thought of would be a damaged spider gear. I have heard of people welding these gears somehow to intentionaly lock the rear end for drag racing. People call me pessimistic when i comes to car repairs but I wouldn't hold out too much hope for fluid changes miraculously fixing your rearend, though I hope it does. Good Luck at E town.

 

Thanks Ralph. I thought the way the limited slip worked was it transfers the power to the wheel with best traction?

Guess you learn something new everyday.......Or does it past a certain point?

:confused:

 

OlRj,

i will try in a large parking lot tonight going in tight circles. I think that is the only time the plates/clutches really "slip" other than that they are 1:1. That is what the poping is I think. They must be moving a little, but not like they should be. That is probably the reason for the loading and unloading feeling. I will try what you suggest.

Like I said, I seldomly drive the car in circles, so all this highway milage is probably not doing a darn thing. Maybe what Ralph said to do with one wheel will work better. To really get a slipping action going. Anything is worth a try at this point.

Thanks!
:cheers: :thumbs:

 

What you say is true to a point, but during a burnout neither tire has traction. Driving in circles may do the same thing....i was trying to force the wheels to turn at different rates so that 1. you can insure the rear is not locked, and 2. you might diagnose it's health based on noise or hopefully lack there of.

For a dragracer, a tight rear can be a good thing....better traction and the girls generally like tight rears....for an inmate it might not be so good

Good luck :crazy:

 

Ralph, if you notice no one turning their backs on you at the drags this weekend. I think its due to the above statement. :jester :D :rofl:

:lolg:

 

Jesse,

Listen to Ralph. He is one of the few that has given you the "straight scoop". With a posi, the rear wheels will turn the same direction when both are off the ground. There is a spec, for the "breakaway torque", where one wheel can be held, and the amount of torque required to turn, or break away the other. Both your description of driving the car and the "test" on the rack, indicate that you have a "tight" posi. It may have been built with extra clutches and/or just have heavier than stock springs, keeping the posi engaged to a higher breakaway torque level. *I* think that for your purposes, what you have is what you would have strived to build, had you put the diff together yourself.

Dominic,

If your unloaded rear wheels turn opposite directions, your posi is worn out. It is totally ineffective and has reverted back to an open rear end. If you want or need a posi traction, it's time for a posi rebuild, new clutches, at a minimum. Good luck, all, and...

RACE ON!!!

 

All limitedslip posi will turn the wheels in one direction , when I got my dana 44 I could turn the front yoke and I can see that the both side yokes turn in one direction , and now that my dana 44 is installed and the dana 36 with only 36k miles is on the floor does the same way , and both of them don`t turn when you try to turn the side yokes in opposit directions !!! On a good limited slip posi you can`t turn the wheels in opposit sides because limited slip posis are made to work like that ,it will only turn under high tourqe occured when you make tight turns !!!!


good luck .

 

CFI,

I appreciate that. I'm confused because whenever I drop the hammer or do a holeshot, I'll get 2 patches of rubber. :confused:

 

Nowhere is it written, that an open differential CANNOT spin both rear tires. If you get two even patches, you are probably fine with an open diff. Be assured, that if one rear wheel spins in the opposite direction of one you are turning, your posi traction is non-functional. I know you don't like to believe anything I have to say, so check with someone else who has worked with rear ends, for 25+ years. Good luck, and...

RACE ON!!!

 

I was not questioning what you were saying nor is it true that I don't believe "anything" you say. I am sincerely confused. I admit to not knowing as much about posi rear ends. I guess I am not clear on what an "open" diff is and how it is different from a posi rear. I looked at my shop manual and couldn't find any clarification on the type of rear the 84 has and what the operating characteristics would be. It shows as a posi with the clutch packs and describes it as a semi-floating rear. So I am interested in learning more.

 

I had this same problem in a 69 Chevelle with a 10 bolt posi. I used to let my friends help with my cars. I was tuning under the hood, a buddy was changing the rear-end lube. A couple of days later SNAP LURCH SNAP LURCH SNAP LURCH...WTF!? Found out he didn't the posi addative. Even after putting it in normal driving didn't eliminate the snapping. A trip to a large parking lot on a Sunday and several max turn, lock to lock figure eights later I drove home gold!

I knew guys that welded their spider gears... :rolleyes:

Save the :seeya

 

Its a broken spider gear locked together. If you do manage to snap it free, it may not even move afterwards.

Dont play around with it...you may be able to save the carrier at this point. If you break it anymore...you might be buying a new D44 carrier.

BTW: There are no bearings that lock the clutch plates. The clutch plates are locked together by a combination of preload from the shim between the spider and the carrier and the actual torque applied to the spider gears from power transfer to either rear wheel. Basically, the torque causes the spiders to climb apart which pushes the clutch elements together to lock the axle spline to the carrier. Due to this design, if the clutch packs have excessive wear, the spider gear mesh is allowed to climb too far, resulting in broken gear teeth.

The spider gears are a cheap fix. You basically do a rebuild on the carrier and new spider gears and your done.

Dont be stupid and break the whole carrier now, hear!

 

Dominic,
First, if your book is relevant to C4's, only, it will not address open differentials. All C4's came with posi. Let me see if I can put this into words that can be easily understood. In an open differential, there are 4 gears. Two pinion gears on the cross shaft, and two side gears. The main pinion drives the ring gear that is bolted to the diff case. The cross shaft is driven by the case. The pinions on the cross shaft, turn the side gears, into which the axle shaft, or half shaft, yoke shafts are splined. When the car negotiates a corner, the differential, the case with the 4 gears inside, allow the outer wheel to speed up and turn faster than the diff case. The inner, likewise, turns slower than the case. When the car is on a rack, turning one wheel, causes the opposite wheel to turn the other direction. In positraction differentials, you have the same components, plus the clutch packs. The clutch packs are a set of lined and unlined discs. Half those discs are splined to the side gear and the other half is anchored to the diff case. These discs resist the turning of the side gear, relative to the diff case. When you turn a corner, the clutches slip, allowing differential action. In a Spicer (Dana) differential, the force that compresses the clutches, is the angle of the teeth between the pinions, and side gears. As resistance is met, the side gears are forced away from the pinions, and into the case. The clutch pack resides between the side gear and the case. This force compresses the clutch pack and causes the side gear to turn at the same speed as the case. In that captive environment, if one item (the side gear) is stopped, relitive to the case, they are all stopped. Differential action ceases and both wheels are force to turn at the speed of the case. Properly set up, there is preload in the clutch pack. When you turn one wheel, on a lift, the other wheel, turns the same direction. Somewhere, not in MY factory manual, either, there is a spec for the amount of torque required to turn one wheel while the other is held stationary (on the ground?). That is a measure of the amount of preload. If turning one wheel causes the other to rotate in the opposite direction, the preload is totally gone. The diff has reverted back to an open diff. Due to the pressure of the gears, you may still be getting a little posi assist at maximum bias, but basically, it's worn out. Picture driving a stick shift car with a clutch, so worn out that the car won't move. That's pretty much what you have inside your differential. Luckily, due to the nature of the differential, the clutch packs don't "drive" the car like the engine clutch does. I hope everyone was taking notes, because there will be a quiz later. Questions? Was that clear, or can I expound on anything? WHEW!

RACE ON!!!

 

:iagree:

 

CFI,

Thanks. Very good explanation. My shop manual is the GM 84 Vette Shop Manual.
Seems like I've got one more thing to fix. Too bad because I just did the brakes and rear wheel bearings. Would have been a good time to take the rear apart.
Isn't that the way it always goes with Vettes? :banghead:

 

OK guys,

Got back from NJ this weekend. First let me say the rear is still in one piece. But still tight after hammering on it 4 runs. All runs were with the car corked up with my restrictive <2" exhuast in spots :) Hence the less than optimum ETs/MPH.

60' times 1/4ET

1.52 11.3@118
1.67 11.5@118(Tires went up in smoke, had to leave off and get back on it)
1.70(WTF?) 11.6@117( terrible traction)
1.52 11.3@116 ( on the brakes through the traps, broke out of my bracket)

The rear during burnouts and runs is silk smooth. Really wrenches the car around in turns. Pops/clicks all through the turns and clunks everynow and again. Almost feels like the rear is walking sideways under the car, then slaps back to normal. I think its the slicks loose sidewalls, and the car is pushing the rims to the side and the tire's contact patch is strong enough to resist, till it hops back to normal.

BBA and CFI, both of you guys sound like you know what is going on. CFI, what scares me about the rear, is that when I first installed it, it did not do this. Now all of a sudden its happening. BBA, do you think the rear would be this quiet with broken spider gears?

What scares me, and the reason I will pull the rear end down and apart when I get the car back from neverlift is the fact that if one of the teeth are missing its floating around in there. I am afraid it might float up to the top or into a place where its caught in the carrier, seazing the entire unit up and possible locking the rear wheels up at 120+ MPH! That would not be pretty, nor do I want to use the cage I'm having installed right now!

I think its in my best interest to pull the cover off the unit. Inspect the pinion teeth, etc, it will be pretty obvious if there is anything wrong with it. If everything is in one piece I will just put it back together. If something is broken. Bingo!

I'm just concerned that it wasn't like that before, and now it is.

You guys thoughts.

One last question. On my Dads Chevelle. Its a 12 bolt. When you spin his rear wheels, they turn opposite directions. Is that right or wrong?

Also what would that do to his 60' times? If it reverted back to open? Both his wheels spin exactly the same in burnouts, but his car doesn't 60' well.??

Thanks guys! :cheers:


[Modified by ski_dwn_it, 9:11 AM 7/28/2003]

 

Jesse, there is some torque spec on the breakaway point on the posi. You might want to call Tom's and ask some questions. If you want i could do an experiment on my car.....but only ask as a last resort. I'd have to remove my rear tires, which in my case is a real pita :crazy:

As for your father's car, see CFI's earlier post. And yes that could definitely have an effect on his 60s. IF it's a properly functioning posi, the wheels should turn in the same direction.

 

Thanks Ralph and CFI for the information in this post!

I will inspect my car when i get it back from Neverlift next weekend.

Also thanks. i think we might have just found out why Dads car will not 60' with an engine equally powerful as mine, and ~ the same weight. His best 60' times are in the mid 160s. I think it should be 60' in the 1.4s with no problems. I know for a fact that his tires turn opposite directions.

Thanks guys! :cheers:

 

Unless he is blowing his tires off, i wouldn't expect a 2 tenth gain in his 60s.

 

Ralph/BBA/CFI,

How much time do you think having an "open diff" would make in 1/4 mile times and trap speed? I don't have the kind of power ski-down-it has, but my CFI is putting down quite a bit of torque(~440lbft). I know I'm a lousy driver but I haven't gotten my 60' times below 2.08. My best 1/4mile was 13.6.Now this is with a 3.08 gear, street tires at 35psi, and a half load of gas.