daw1@rduxb.UUCP (WILLIAMS) (06/26/85)
*** REPLACE THIS DIFFERENTIAL WITH POSI *** I have a question about 4 wheel drive operation and differentials. Does one really only have "two wheel drive" after shifting into four wheel drive and locking the hubs? I ask this because without a limited-slip differential at each end, power is not transferred optimally to each side of the vehicle. First of all, take your ordinary Chevy sedan without a posi rearend. With one tire on ice and the other on dry road, the one on ice will spin and the other does nothing. You are stuck! But with a posi rearend the tire on dry road does get power to it and you are not stuck. This is why posi is good(among other reasons). The only negative aspect some people may find is that by having power to both rear wheels, the rear of the vehicle can break loose easier, rather than only having one tire spin. Now take a Jeep CJ for example. Is the front differential of a different design than normal differentials? If it is a regular-type diff., and the rear happens to be a regular type too, what happens? I'd be stuck if one front and one rear tire are on slippery patches and the other two tire sit there useless. So, I'd really have "two wheel drive": one front and one rear! If this is wrong, please correct me. As it stands now, however, it seems like a limited slip rear diff. is a damn good investment. And, only Ford offers a limited slip for the front (but maybe their standard front diff. is lousier than most). Any responses relating to modern 4x4 systems would be greatly appreciated. Doug Williams Reading, PA mhuxt!rduxb!daw1 -or- mhuxt!rduxb!williams
jeepcj2a@fluke.UUCP (Dale Chaudiere) (07/02/85)
> > I have a question about 4 wheel drive operation and > differentials. Does one really only have "two wheel drive" > after shifting into four wheel drive and locking the hubs? > I ask this because without a limited-slip differential at > each end, power is not transferred optimally to each side > of the vehicle. Yes, you are describing conventional 4WD. But don't kid yourself, one front tire and one rear tire with traction can get you through snow, mud, and sand that 2WD w/limited slip will not. In a 2W(rear)D vehicle you are pushing all that dead weight up front, mainly the engine. Front wheel drive has better traction, unless the rear is loaded. > First of all, take your ordinary Chevy sedan without > a posi rearend. With one tire on ice and the other on dry > road, the one on ice will spin and the other does nothing. > You are stuck! But with a posi rearend the tire on dry road > does get power to it and you are not stuck. This is why > posi is good(among other reasons). The only negative aspect > some people may find is that by having power to both rear wheels, > the rear of the vehicle can break loose easier, rather than > only having one tire spin. > Now take a Jeep CJ for example. Is the front > differential of a different design than normal differentials? > > a regular type too, what happens? I'd be stuck if one front > and one rear tire are on slippery patches and the other two > tire sit there useless. So, I'd really have "two wheel drive": > one front and one rear! 2WD? not in the standard sence. See above or have a buddy take you out in his/her conventional 4WD. > If this is wrong, please correct me. As it stands now, > however, it seems like a limited slip rear diff. is a damn good > investment. And, only Ford offers a limited slip for the front > (but maybe their standard front diff. is lousier than most). Yes, it is one of the best improvements you can make to a 4WD. > Any responses relating to modern 4x4 systems would > be greatly appreciated. > Jeep Quadratrack is slightly different, it has a limited slip in the transfer- case. Power is sent to the axle with the most resistance to rotation (traction). If a limited slip is installed at each differential than the power truly goes to the wheel with the most traction. (This is the way it is supposed to work. I have never owned a Quadratrack system.) > Doug Williams > Reading, PA > mhuxt!rduxb!daw1 > -or- > mhuxt!rduxb!williams