Any tricks to get open diff to hook?

[bgilbert]

This might be a stupid question to ask. Say at the drag race track. Are there any tricks to get an open rear diff to hook? Would tire pressure have any effect on getting both tires to hook? Say rock hard 80psi in one, this way it's tall and has less thread to pavement contact. Then something like 40psi in one (or less), fatter, more thread to pavement contact..... Or something else? Or am I puffing too much diesel smoke?

For some reason, the open diff in my 89 stick truck will hook and burn both tires. The 91 auto truck at any given moment will readily slip the rear passenger side tire . Don't even think about doing a boosted launch. It will just sit there and smoke the right rear tire.

[CAJUN 93]

sadly, there isnt much you can do to improve the traction of a peg leg rear-end (short of welding the spider gears, but that aint to good for highway driving ). the problem is that even though it appears to transfer vehicle weight to the rh rear on launch due to engine torque, the rotation of the driveshaft does it's best to lift the rh rear tire of the ground. about the only thing you can do is to stiffen the rh suspension (airbag) enough to attempt to counteract the rotational force of the driveshaft.

btw, varying tire pressures and such will make a difference down low but makes for a squirrely ride up top, i dont recommend it.

btw II, for your 89 with an open diff to spin both tires, the spiders are in a bind. you may want to inpect it to be sure the pin isn't backing out. that aint normal

[seeker1056]

for pullin purposes only you can apply the emergency brake about half way so the power is evenly distributed for 300'

I caution u - pullin only lol. Dont wanna burn up that rear brake shoe.

[seeker1056]

there is one more trick if u have acess to something u can slightly spread the diff case with.

We used to take an extra shell bearing for the spider gears an install it on the gear then spread the case to allow the spider gears to be installed,

Once u let the case come back to normal, there was enough extra load on the side/spider gears to keep em locked up for all intents n purposes, but would allow turns

Not sure if a dodge carrier uses shell bearings behind the spiders, but you could get sum for a Ford or Gm and install em

[PToombs]

Buy a locker you cheap ba... oooops, sorry! Cheapskate!

[seeker1056]

best thing in a locker these days is a Lockrite - just pull yur old spiders n side gears n this thing slips right into place in your exisitng carrier - no muss no fuss, and only around $325 US

[PToombs]

I put 1 in a buddys jeep. It was an easy install. Just had to watch the instructions, I think (3 years ago!) you had to make sure of the clearence, there were 2 versions it fit in. Worked good!

[Paccool]

Crap, I can't get mine to hook up and I've got a good limited slip! I can imagine the trouble with an open diff.

One thing that really improved mine is to warm up the tires first. That made a huge difference in traction. Drop the pressure to about 30 PSI will also help.
BUT - as all the guys here say, you need a locker or limited slip. Mine spins 'em both when going in a straight line.

[90firstgen]

Mine is an open diff too but it seems to hook very well most of the time. I usually spin both tires all the time unless I'm power braking on pavement. EVen a hard launch on pavement will leave two black marks almost identical in length. The left is usually about 25% shorter than the right. Makes me wonder why that is....

[Begle1]

Mine is an open diff too but it seems to hook very well most of the time. I usually spin both tires all the time unless I'm power braking on pavement. EVen a hard launch on pavement will leave two black marks almost identical in length. The left is usually about 25% shorter than the right. Makes me wonder why that is....

Are you sure that it isn't limited slip?

[Ace]

There is a couple things you can do, but I'm curious why or how an open diff could turn both wheels on the stick truck. That don't sound right right. Are sure it is open?

On the auto truck you could try putting an air shock on the passenger side and inflate it to max. This will resist initial torque-induced chassis twist. It sounds like spring rebound is letting that wheel go about a split second after you hammer it. If the springs get weak enough or traction conditions ar right (wrong?) it will manifest as wheel hop.

[90firstgen]

Are you sure that it isn't limited slip?

I'm completely positive. Wasn't on the window sticker I've had the diff cover off. Just plain old ring and pinion setup. My old man's 93 is limited slip. We've had the cover off of it too. I'm not the smartest person in the world when it comes to rear ends and how they work but it didn't have any "clutches" or whatever you call them in mine like my dads did. Limited slip would still turn both tires during a sitting still power brake wouldn't it? The left one doesn't turn at all during that. I'm boggled now.

[wannadiesel]

Sounds like the clutches are toasted. When I got my truck I thought it had an open diff because only one side would spin - turned out the clutches were pretty much gone.

[90firstgen]

Woops sorry Dave. Sometimes my grammar amazes me. My pickup (90) will only spin the one tire during a power brake. My dad's 93 I'm sure would spin both if it had enough power. It feels like the LSD is really tight in it. Turning corners kinda sharp will skid the tires ya know. Can the LSD's bind up? Almost feels like full posi sometimes. Under hood sticker says its a 60/40 LSD. I'm guessing that's the only one available.

[Ace]

Limited Slip, Posi-trac, Sure-grip, No-spin: All are terms describing various types or brands of "non-locking" differentials. These diff's performance falls somewhere between the open one-wheel wonders on the bottom end of the scale and the full spool, race-only drag application at the top end. Your order of locking effectiveness goes something like this, best-to-worst:

Spool (basically a one-piece non-differentiated axle center), Locker (mechanically locked diff), Posi (friction joined diff - clutches, cones), Open (spider gears).