Kevin 007
Full-floater
Nice slick bottom! So therefore Dana 70. Also has 70U embossed into the pumpkin which is very legible. And thats as far as I got.
Rear diff options
- Thread starter Kevin 007
- Start date
madpogue
Full Access Member
Also indicates LS/open.
The OP already mentioned it's a 70, and from post #1, wanted to know if there's a way to determine whether it's an LS.
Kevin 007
Full-floater
Well since I can't really get anywhere with identifying what I have by any external markings, I'm going to assume that it's an open diff as it has never ever locked up when I have needed it to, so; i would like to order a LS unit to install while I have the axles out in a few weeks for brakes and I need a fluid change also. Does anyone know a good source to get all the LS parts that I need?? What all Can I reuse in my current diff??
If it is an OPEN carrier, and you want a POSI or Limited slip, you will have to replace the carrier so you can only re-use the ring gear and bearings really and why not install new bearings while at it? This is referring to a clutch type posi..
If you choose a Lunch box locker which is the least expensive and simplest you don't need to change anything except spider gears out and locker in.
Now this won't give a posi it will be LOCKED or unlocked depening on when where power is applied.
IMHO a lunch box would be a decent compromise if you can handle the clunks and changes in how it drives.
ICY roads are fun but good chains or winter tyres make a difference. ICE/Gravel...never a problem again...yer rolling
Pavement/mud...your rolling...
Locker is good but does take some getting used to where a limited slip is seamless.
If affordable a Detroit True Trac the one with Helical gears is also a nice beast...but $pendy
http://www.youtube.com/watch?v=LTXvH3T8Bsg
Lots of choices, so start with need/want/cost/installation...and decide what is best for you.
If you have to open the diff and look you will know if you have a posi that's worn out cause you will see clutches in the sides of the carrier....so you can do that now or wait till it is time to do brakes.
JM2CW
Kevin 007
Full-floater
I think I should go with a limited slip as I do a lot of highway driving and the lunchbox may be too harsh for what I'm looking for. Thanks so much for the helpful advice and videos. What's a good brand/source for a LS setup?
madpogue
Full Access Member
Did you ever look at the door jamb sticker?
PwrSmoke
Full Access Member
Sorry, been away and couldn't help with this.
Every once in a while, you find axles with no stamped BOMs. The tag on the diff cover will identify whether it has an LSD or not but those tags are often left off during service or corrode off. Frankly, if you have a factory LSD, I don't thinks it's worth a whole lot. I concur with Riotwarrior about the lunchbox lockers. Way too harsh for a daily driver that you aren't going to four-wheel alot... which might make the tradeoffs bearable.
I also concur about the Trutrac. Magnificent unit! I have had one in my '86 for 10 years now. It's more effective than any mild mannered clutch type LSD but it's very transparent, Best of all, it doesn't have clutches to wear out, so it remains as effective at 150K miles of use as it was at 2K miles. A factory LSD has usually reverted to an open diff by 60-80K. The Trutrac costs more and is a more difficult installation but it's the Caddy of the LSD choices IMO. Yukon Gear might have a Powr-Lok application (a "true" Powr-Lok). That is my second choice. They are very effective but can still have good manners. They can be "loaded" to be more effective but that usually comes with some tire barking and bad-manners stuff on the street. They also last longer than most and are very rebuildable as needed. I also like the Eaton Posi with its carbon fiber clutches. They are fairly mild (can be loaded) but the last longer than most. I also like the Auburn Gear limited slip. Good manners, effective long wearing and relatively inexpensive but because they use cone clutches rather than plates, they are expensive to rebuild (usually cheaper to replace) and they are picky about oil. All the units but the Truetrac have special oil requirements, BTW. Event the Truetrac does to a degree in that the manufacturer specifies a mineral oil and NOT a synthetic.
Every once in a while, you find axles with no stamped BOMs. The tag on the diff cover will identify whether it has an LSD or not but those tags are often left off during service or corrode off. Frankly, if you have a factory LSD, I don't thinks it's worth a whole lot. I concur with Riotwarrior about the lunchbox lockers. Way too harsh for a daily driver that you aren't going to four-wheel alot... which might make the tradeoffs bearable.
I also concur about the Trutrac. Magnificent unit! I have had one in my '86 for 10 years now. It's more effective than any mild mannered clutch type LSD but it's very transparent, Best of all, it doesn't have clutches to wear out, so it remains as effective at 150K miles of use as it was at 2K miles. A factory LSD has usually reverted to an open diff by 60-80K. The Trutrac costs more and is a more difficult installation but it's the Caddy of the LSD choices IMO. Yukon Gear might have a Powr-Lok application (a "true" Powr-Lok). That is my second choice. They are very effective but can still have good manners. They can be "loaded" to be more effective but that usually comes with some tire barking and bad-manners stuff on the street. They also last longer than most and are very rebuildable as needed. I also like the Eaton Posi with its carbon fiber clutches. They are fairly mild (can be loaded) but the last longer than most. I also like the Auburn Gear limited slip. Good manners, effective long wearing and relatively inexpensive but because they use cone clutches rather than plates, they are expensive to rebuild (usually cheaper to replace) and they are picky about oil. All the units but the Truetrac have special oil requirements, BTW. Event the Truetrac does to a degree in that the manufacturer specifies a mineral oil and NOT a synthetic.
dont need alot of power to get out of a slick istuation. Hell i woulda been hapopy with my 2wd cclb if it had a locker in the rear.
Kevin 007
Full-floater
None of the local wreckers have any factory LS rearends so upon further research, I'm nearly certain that I want a Powr-lock. Seems like a robust unit that would also be plenty tame for daily driving. Some folks seem frustrated that they don't lock when one wheel is in the air as the need "some" traction in order to work. I don't ever put wheels in the air 4xing this truck so that doesn't bother me.
PwrSmoke
Full Access Member
This is true of ANY limited slip. Less so with LSD that have a lot of preload (the amount of clamping forces built into the clutch packs... which is enhanced by gear separation forces in the spider and side gears). Highly preloaded LSD, however, are as bad or worse than a locker in the bad manners department. At least with a Detroit you can finesse them into some manners with driving technique. A loaded LSD is a barking ******* all the time no matter what! ( : < )
There is a simple answer anyway... the parking brake! If you partially apply the parking brakes, they apply some "artificial traction" and encourages more torque transfer. You can do the same thing with a little foot brake (ala the brake pedal modulation technique they teach at the Hummer Driving School) but because of brake bias (to the front) you increase the amount of traction needed by having a little front brake applied, though with a 4x4 presumably you are using it and the modulation technique will do the same work on the front axle. The parking brake applies only on the rear axle, so it tends to equalize traction without too much extra drag up front The same trick works with open diffs, by the way.
The basic rule of differential action is thus: The average speed of both axles (wheels) will always equal the speed of the ring gear. Going straight down the road with the ring gear at 100 rpm, both wheels are at 100 rpm: 100+100/1=100. In the mud with one tire spinning at 200 rpm and the other stationary: 200+0/2=100. Going around a turn the outside wheel is at 150 rpm and the inside is at 50: 150+50=200/2=100, If one wheel is spinning and you slow it down the other wheel HAS to speed up by as much as the spinning wheel has slowed down. The speed differential is always according the the "ratio" of the side and spider gears (count the teeth to figure the ratio). The clutches in an LSD are nothing more than "brakes" that force the differential to transfer torque. That braking for comes from the clutch preload as well as gear separation forces. When torque is applied to the differential, the spider and side gears try to push apart. Because there are clutches under the back side of the side gear, that increases the amount of preload on the pack and the amount of braking. With a wheel in the air, there is no torque to that aspect is gone, hence the need for the wheel brakes.
Anyway, the Powr-Lok is a good choice in a limited slip. The Truetrac is better but a lot more expensive.
madpogue
Full Access Member
^^^^^^ Denominator in your first equation should be 2. Sums in all equations should be in parentheses, so you don't (precedence rules) divide before you add.
PwrSmoke
Full Access Member
Yep, you stole the show all right!
Kevin 007
Full-floater
So after some research I discovered that the axle code 73 (which is what my door jam says) is a 3.54 "NON" limited slip diff
Kevin 007
Full-floater
So I have decided on a PWR-Lock limited slip. What is a good source to buy from??
Thanks everyone
Thanks everyone
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