hank@masscomp.UUCP (Hank Cohen) (11/04/85)
In article <2180@amdahl.UUCP> ems@amdahl.UUCP (ems) writes: >> > 2) The bearings in the rear end have started to hum. How much damage >> > can I expect if I wait a few months to replace them? >> > >One thing to watch out for is *front* bearings. (I know the original >was about rear bearings, but this is important). My sister had a small >Ford that had the front bearings go dry (grease 'evaporated'). The >result was a noisy front bearing. This first manifested itself in Los >Angeles. As home was north of San Francisco, she decided to just >drive it home before getting the bearing fixed. After several hours >on the freeway noise was worse and the performance was off. >She stopped at the request of a friendly Highway Patrolman ... The >wheel then fell off. A *VERY* overheated bearing had softened the spindle >it rides on enough for it to break. It was a dull red at the time... > Another issue with overheated front wheel bearings is that they become VERY difficult to replace. The inner bearing race can freze to the spindle making what should be a rather simple repair into a real monster. Why risk it, bearings are cheap compared to new spindles. Iligitimi non carborundum Hank Cohen
pz@emacs.UUCP (Paul Czarnecki) (11/05/85)
> Hank Cohen writes: > In article <2180@amdahl.UUCP> ems@amdahl.UUCP (ems) writes: > > > >One thing to watch out for is *front* bearings. My sister had a small > >Ford that had the front bearings go dry (grease 'evaporated'). The > >result was a noisy front bearing. ... she decided to just > >drive it home before getting the bearing fixed. After several hours > >on the freeway noise was worse and the performance was off. ... The > >wheel then fell off. A *VERY* overheated bearing had softened the spindle > >it rides on enough for it to break. It was a dull red at the time... > > > Another issue with overheated front wheel bearings is that they become > VERY difficult to replace. OK, what is the difference between a bearing an a CV joint. My 1981 Dodge Omni, (yup readers, the same one) has "worn front CV joints". On one of them (drivers side) the rubber bag that holds the grease is ripped. The grease can disappear. I was quoted at $270 ($240 labor, $30 parts) to repair this front wheel drive, traverse engine car. The mechanic said that it need not be done soon. The wheel would eventually fall off but I would get plenty of warning before that. I don't plan on keeping the car much past Sep '86. (Or maybe even sooner if the VW GTI gets the 16 valve engine in this country earlier than expected) Any prognosis? Suspension is also going soft. Given the above, should I fix it? What would an approximate cost be? "Devil in my car!" pZ -- -- Flushed from the bathroom of your heart. Paul Czarnecki Uniworks, Inc. decvax!{cca,wanginst!infinet}!emacs!pz 20 William Street emacs!pz@cca-unix.ARPA Wellesley, MA 02181 (617) 235-2600
oneill@lll-crg.ARpA (Neil J. O'Neill) (11/08/85)
> OK, what is the difference between a bearing an a CV joint. My > 1981 Dodge Omni, (yup readers, the same one) has "worn front CV > joints". On one of them (drivers side) the rubber bag that holds > the grease is ripped. The grease can disappear. ... CV or constant velocity joints serve the same purpose in a front wheel drive car that U-joints serve on a rear wheel drive car. That is, they allow a flexible connection between the transaxle ( or transmission) and the drive wheels. On a fwd car there is a CV joint at each end of each drive shaft. One connects to the transaxle and the other to the wheel. They are called constant velocity joints because they provide for the linear transfer of angular velocity through the joint. That is, if a shaft on one side if the CV joint is run at a constant 3000 RPM a wheel connected to the other side will run at a constant 3000 RPM regardless of the angle of the joint. If you run a constant 3000 RPM into a U-joint you will get an output that only averages 3000 RPM but actually speeds up and slows down during a single revolution (play with the U-joints in a socket-wrench set and you will see what I mean). This non-linear transfer of rotation depends on the angle of the U-joint. For a straight joint the effect is zero. And for the small angles encountered in rear wheel drive it is negligable. However, it cannot be neglected in the angles encountered in a fwd car. The angles are greater because the drive shafts are so much shorter and the wheels also have to turn to steer. So fwd cars use CV joints so that their drive trains don't self-destruct. The CV joints have ball-bearings inside of them, but these are not the front wheel bearings. The front wheel bearings are the ball|roller| taper bearings that allow the front wheels to spin smoothly inside the wheel housing. If the CV joint protective boot is cracked then grease can get out and water can get in and it would not be suprising if the joint wore out in short order. So called "split-boot" kits can be obtained which allow you to replace the boot without taking off the drive shaft -- the boot is split and you glue it back together after wraping it around the shaft. I have one of these on my Rabbit and it seems to be holding up. It is possible that your CV joints just need to be repacked with grease; you might want to ask your mechanic about this. oneill@lll-crg.arpa
axa@panda.UUCP (Andrew Alvino) (11/08/85)
>CV or constant velocity joints serve the same purpose in a front wheel >drive car that U-joints serve on a rear wheel drive car. That is, they >allow a flexible connection between the transaxle ( or transmission) and >the drive wheels. On a fwd car there is a CV joint at each end of each >drive shaft. One connects to the transaxle and the other to the wheel. >They are called constant velocity joints because they provide for the >linear transfer of angular velocity through the joint. That is, if a shaft >on one side if the CV joint is run at a constant 3000 RPM a wheel connected >to the other side will run at a constant 3000 RPM regardless of the angle >of the joint. If you run a constant 3000 RPM into a U-joint you will get an >output that only averages 3000 RPM but actually speeds up and slows down >during a single revolution (play with the U-joints in a socket-wrench set >and you will see what I mean). This non-linear transfer of rotation >depends on the angle of the U-joint. For a straight joint the effect is >zero. And for the small angles encountered in rear wheel drive it >is negligable. However, it cannot be neglected in the angles encountered >in a fwd car. The angles are greater because the drive shafts are so much >shorter and the wheels also have to turn to steer. So fwd cars use CV >joints so that their drive trains don't self-destruct. if this is true, then how can I have universal joints at each front wheel on my solid front axel jeep cj-7 4x4 and my independent front suspension bronco II 4x4 ?
ccrse@ucdavis.UUCP (0058) (11/12/85)
> > > OK, what is the difference between a bearing an a CV joint. My > > 1981 Dodge Omni, (yup readers, the same one) has "worn front CV > > joints". On one of them (drivers side) the rubber bag that holds > > the grease is ripped. The grease can disappear. ... > > If the CV joint protective boot is cracked then grease can get out and > water can get in and it would not be suprising if the joint wore out > in short order. So called "split-boot" kits can be obtained which allow > you to replace the boot without taking off the drive shaft -- the boot > is split and you glue it back together after wraping it around the shaft. > I have one of these on my Rabbit and it seems to be holding up. It is > possible that your CV joints just need to be repacked with grease; you > might want to ask your mechanic about this. At least on the car in question, the CV joints don't seem to be particularly touchy about contamination/loss of lubricant. As long as the boot is repaired and the lubricant replaced within a reasonable period of time, the CV joint doesn't seem to suffer too badly. Changing the boot is not one of my favorite jobs, though. I am curious about the so-called "split boot" kits mentioned above. Anything that eliminates the need to remove the drive shaft from the car certainly sounds attractive to me. Has anyone else had experience with these kits, and/or know if they are applicable to late-model Chrysler FWD cars?