My rough understanding of CV joints follows. Perhaps the physicists or engineers among us can correct me if I fall short here.
CV joints are joints which allow two connected components to turn at the same velocity, even when the point of rotation for each component is not on the same plane. Standard u-joints will not allow two components to do this. Standard u-joints will only allow two components to turn at the same velocity when the separate ends of the shaft are on the same plane. If the two shafts are not on the same plane, there is some loss of velocity from the driving shaft to the driven shaft.
Typically, the two components connected by CV joints are engine and wheel, as on a FWD auto. It's possible though, for a RWD car with independent rear suspension to have CV joints in the rear. In the case of the IRS car, the connected components are the differential and the rear wheels. When you consider this, it may even be possible for a 4WD vehicle to have four sets of CV joints, a set for each shaft driving a wheel.
I agree with the comparison of Constant-Velocity (CV) and standard Universal joints but would like to attempt use of some alternate terminology.
Two shafts, connected by a CV Joint, will rotate at the same speed whether or not their axes are parallel.
Two shafts whose axes of rotation are not parallel, will not have a precise speed match if they are connected by a standard U-Joint. The average RPM of these two shafts will be the same but, if the first shaft rotates at a uniform speed, the second shaft will speed up and slow down a small amount twice within each rotation.
If this second shaft is now connected to a third shaft with another standard U-Joint, the third shaft will rotate at exactly the same steady speed as the first shaft if the following two criteria are met: * The first and third shafts are parallel * The second shaft is constructed with its two end yokes in the same plane. In practice, consider a conventional rear-wheel-drive car. If the transmission tailshaft is parallel to the differential pinion shaft, even though these two shafts are not on a common line, the tailshaft and differential pinion speeds will be the same. The driveshaft RPM, however, will have two cycles of speed variation per revolution. The amplitude of the variation increases with an increase in the angle between the shaft axes.
I have a 1988 Ls Cougar, V8, fully loaded that ran great until just recently. Oil pressure light kept beeping. Mechanic says needs bearing in lower motor. I have 74,000 miles! Do not want to put the $2500 into. What should I expect to get for car that virtually has no engine. PS The car still runs. It just makes a rattle when you start it.
I'll answer this question for you. Most self-storage places that are large enough have outdoor parking available for $25-$50 a month. You could rent a 10'x20' storage unit for $60-$80 and put it in a garage. Or put it in the backyard. Or sell it to a neighborhood kid for $1000 after you are sure your next car is going to last.
Just throwing my 2 cents in here, and I may well in fact be wrong. But I was under the impression that some (maybe most) FWD cars have both an inner and outer CV boot, one by the wheel and one by the tranny. I do know for a fact that my 91 VW Passat has an inner and outer CV joint and boot. Therefore replacing 4 of them on a FWD car would not be incorrect or maybe not that bad of an idea, why pay the extra labor to have 1/2 replaced one time and the other half in a few months?
Basically, there are two axles on a FWD car, a left axle and a right axle. Each axle has two CV joints, an inner (at the transmission/transaxle) and an outer (at the wheel). It is possible for the boots on one side to be worn worse than the boots on the other side. In this case, only two boots would be replaced instead of the car's full compliment of four boots. In many cases the only advantage to doing both sides at once is that you only need to drain and refill the transaxle once instead of twice.
IF your going to replace one CV boot you may as well replace all. The only exception is if 500 miles after you did all you hit a rock that tore a boot. Otherwise once you have the wrenches out do it all.
Yes I agree that you can often get by without, but why try? Rubber gets old, and bad CV boots can cause expensive repairs in comparition to the cost of the boots.
BTW, my understanding is that you can get split boots that can be installed with little effort. Cut the old one off, slip the new one one, and clamp/glue it down. If so it would make CV boots easy to do. This won't work if the old boot is cracked, but if the old one is just worn and you want to replace it before problems start it is a good idea.
IF you're going to replace one CV boot you may as well replace all.
I will disagree with you on this point, but I'm not trying to start an arguement. I will agree to disagree because I know many people who will make the case for this. My opinion is that you should do both boots on an axle if one of the boots on an axle is torn. You should not pull the other axle to do the boots on that axle if there is nothing wrong with those boots. If those boots are beginning to show serious signs of wear, then yes, you should do them.
with 163,000 miles. Engine (5.0 ltr) still runs great (averaged 24 mpg on a 300 mile round trip a few months ago) but the transmission has been slipping (usually when its cold and I put it into drive, there is a hesitation before the transmission shifts).
Mechanic changed the fluid (it was burnt) and cleaned the filter). He said this will extend the life somewhat, but the transmission is on its last legs. He said to put in a new transmission will cost approximately $1,200. Do you think its worth it to put this kind of $ into a car with 163K miles, or is it time to put the old T Bird out to pasture?
What shape is the body in? If it has been totaled, or is rusting through don't put more into it. If it otherwise in good shape cars tpically average $1,000 a year in maintance, so this year is high, next year is low.
Why put a new transmission in? Often you can find a junk yard transmission that will fit, at much cheaper. I'm not sure, but I think a '91 is old enough that a new transmission is a simple fix, relative to other jobs.
All this assumes you care to keep this car, if you are sick of it why put money into it? Note that you won't be able to get much for it without doing transmission work, but can you get that back?
Since your engine is good, you might be able to find someone else who needs that engine to buy the car, and option.
The Body is in good shape, no rusting and interior is still good. Got a price quoted of $1,195 for rebuilt transmission (including installation) with a 1 year warranty.
I have a 1992 Dodge Dynasty. I purchased it fairly cheaply and now that I have no second job I would like to tackle the air conditioner. The previous owner spent nearly $2000 on the AC system over the years. My mechanic says the evaporator is leaking. He wants $450-$500 to replace it. That sounds ridiculously high. All it is is a tiny core that looks like a heater core all wrapped up in the blower motor box. If I replace this thing myself and spend my weekends with my head stuffed under the dash putting it all together, would my mechanic be willing to charge it up after that? The system has been changed to R-134a, the compressor is new and pretty much unused since the system won't hold a charge, the condenser and radiator and assorted plumbing are new, and the filter/drier was replaced with the conversion. Are there any other parts that could fail in the AC system? If I go ahead and change the evaporator myself then spend the money to get it charged and it fails, then what do I do? What else is there to fix?
I have a '91 Previa DX van with auto 4-speeed, cruise control, power windows, tilt steering wheel, 7 passenger seating, dual air conditioning, rear window defroster, AM/FM stereo tape, power door locks, and rear window wiper and 172,000 miles. My mechanic told me the front power takeoff shaft that runs the compressor and alternator needs to be replaced for $800 to $1000. We are wanting to buy a new car but I am unsure what to do with our old van. Should I try to sell it myself? Should I donate it? Should I try to get it fixed? Where can I get an unbiased appraisal? Thanks for your help. Ger
I need your help everybody. I own a 1992 dodge shadow 4 door, 2.2L engine, automatic, it has 187000 km. I bought it 4 years ago at 64500 km. The person before me followed the service manual to the letter, and I've been changing the oil every 4000 to 5000 km. I changed the timing belt about 15000 km ago and the car runs fine. Currently, I know that I will have to change in the next 6 - 8 months from now the oil pan gasket, rear breaks, rear shocks, alternator, starter, something in the exhaust (I'm not sure what), something in the front end (I'm not sure what, but I do here not a good sound).
So, what should I do. The engine and trans. is sound, so far. Should I fix it all and keep it until it dies, or should I go out and buy a new one.
I have a 1989 Pontiac Grand Am w/88,000 miles on it. Lately I've been hearing a noise coming from the engine, like spark knock, only louder. I don't hear it at idle or when decelerating, only on acceleration or cruise speed. I use 93 octane gas. Any ideas on the problem?
guy1, I hear those Shadows are great little cars. My mom owned a turbocharged one for years and loved it. My suggestion is this: If it's going to cost more to fix the car than it will to buy one as good as your dodge will be when fixed, then Buy. If you can fix yours for less than what you can buy a comperable car, then fix. Personally, I drive cars till they fall apart, duck tape them together again, and drive them some more, but I'm sure everybody is not as madly in love with their cars as I am mine.
dlk9584, My guess on your knocking problem would be a loose piston rod. Take the oil pan off the bottom of the engine, and make sure all of the rods are firmly attached to the crankshaft. If one is loose, you could probably get away with tightening it up, but to be on the safe side I'd get a service manual and make sure all that knocking hasn't worn anything down to the point where it's out of spec.
Like rea98d, I like to keep a car 'til the wheels fall off and recently retired a '77 Pontiac wagon and had my '87 Stanza totaled in a moderate accident. Trading up nearly involves some reliability uncertainty, higher costs of interest and depreciation in place of repair and upkeep on the older car, but I like very much the safety features of my '95 Subaru Legacy dual air bags and ABS.
I have an '89 Mazda with 245k miles on it. It needs a new transmission. I have been warned by several that it is not wise to invest money into the car that I should go get a new one. The engine sounds strong. I am not car wise at all, should I really abandon my car for something new. I was hoping it would last another 12-18 months. But quite frankly it has reached the age of costly repairs and this year I have had to replace several things.
I need some advice. I drive a 95 MaximaSE with 68000 miles on it. Was having trouble starting ...replaced the battery and starter. In addition I repaced the brakes and had dealer service done at 60000 miles all at a grand total of $2000. The car is running fine but I wonder if it's time to trade. The value of the car continues to fall and seems like it will require more money to maintain. Do I trade or keep?
My 94 Camry Transmission just died. 80K miles on the car. It is in very good condition and we planned on giving it to our college-aged son next summer. We were quoted $3000 for a "new, re-built" tranny and $1700 for a tranny the dealership found with 68K miles on it. What would you do? Do these prices seem high to you? Thanks! saraguigou
Okay, first of all "New, rebuilt" is a contradiction in terms. It's either new (never been in a car before), or rebuilt (someone else's blown transmission that has had all the worn or broken parts repaired or replaced). I know we're looking at a whole other bucket of worms, but I was quoted about 350 for a rebuilt FMX transmission for my 78 Grand Marquis. Try Autozone or some place like that. And NEVER take a car to the dealer for repairs unless they're doing it under warranty. You can get the same quality work from any ASE certified mechanic, and at a lot less money. And if you can get a better price on the tranny, by all means keep that Toyota. If you're son stays in school till he gets a Ph.D. (Don't hold your breath), he'll still be driving that thing.
Hi. I need to choose which of my two old cars to trade-in on a new purchase. Both have comparable trade-in value so I am mostly concerned with which car has a better chance of surviving a few years without major expense as my commuting car. The two cars are (1) 1990 Dodge caravan with 2.5 L v4, base model, with 112K miles and (2) 1988 Pontiac Lemans Aerocoupe with 1.6 v4 and 83K miles. They are both in similar condition and similarly maintained. The Pontiac has an oil leak (probably pan gasket) and ac leak.
I am tempted to keep the Lemans due to its lower miles but I have heard nothing good about its reliability. The van is basic and should be cheaper to repair but, with more miles, costly repairs may not be far away. I bought the Lemans new in 1988 and the van used with 75K miles in 1995. The van has had some body accident damage repaired (professionally) at least twice.
As a shop owner in southern Oregon, I marvel at some of the high $ estimates listed here for repairs. I do many of the listed repairs for considerably less $, must be doing something wrong.
It is important to remember that if the cost of currently needed repairs + cost of potentially needed future repairs come close to or exceeds the retail value of the auto, it would be wise to consider not repairing. REASON: In the event of an insured loss to the vehicle, the owner will not be able to recoupe all the repair investment. Any repair made just prior to an insured loss will not add an equal value to the auto. Example, rebuilt trans., total cost- $1600.00 will increase the value of the auto aprox. 50% of cost.
Questions that need to be answered: Value of vehicle? current needed repair costs? potential future needed repair costs?
How to anticipate future needed repair costs: There is no sure way to know, but a number of factors will play. Vehicle model, miles, TYPE OF USE (light, normal, severe) & quality of service. Keep in mind the average life of the modern automobile is 100,000 miles, even though there are many we hear of that go much further.
If an owner finds a need for major component repair & wants to know what other major repairs may be around the corner, the best person to talk to is a dependable, honest repair person, or shop owner. Questions to be answered: Eng. fuel mileage? eng. fuel emissions? engine noises? eng. bearings (physical inspection may be necessary)? eng. oil consumption? trans. shift diagnosis(auto)? drive train condition? brake component condition? steering component condition?
There is no problem with repairing older vehicles at a cost greater then its retail value as long as the owner understands the risk of the event of an insured total damage or theft loss.
Comments
CV joints are joints which allow two connected components to turn at the same velocity, even when the point of rotation for each component is not on the same plane. Standard u-joints will not allow two components to do this. Standard u-joints will only allow two components to turn at the same velocity when the separate ends of the shaft are on the same plane. If the two shafts are not on the same plane, there is some loss of velocity from the driving shaft to the driven shaft.
Typically, the two components connected by CV joints are engine and wheel, as on a FWD auto. It's possible though, for a RWD car with independent rear suspension to have CV joints in the rear. In the case of the IRS car, the connected components are the differential and the rear wheels. When you consider this, it may even be possible for a 4WD vehicle to have four sets of CV joints, a set for each shaft driving a wheel.
Two shafts, connected by a CV Joint, will rotate at the same speed whether or not their axes are parallel.
Two shafts whose axes of rotation are not parallel, will not have a precise speed match if they are connected by a standard U-Joint. The average RPM of these two shafts will be the same but, if the first shaft rotates at a uniform speed, the second shaft will speed up and slow down a small amount twice within each rotation.
If this second shaft is now connected to a third shaft with another standard U-Joint, the third shaft will rotate at exactly the same steady speed as the first shaft if the following two criteria are met:
* The first and third shafts are parallel
* The second shaft is constructed with its two end yokes in the same plane.
In practice, consider a conventional rear-wheel-drive car. If the transmission tailshaft is parallel to the differential pinion shaft, even though these two shafts are not on a common line, the tailshaft and differential pinion speeds will be the same. The driveshaft RPM, however, will have two cycles of speed variation per revolution. The amplitude of the variation increases with an increase in the angle between the shaft axes.
PS The car still runs. It just makes a rattle when you start it.
Yes I agree that you can often get by without, but why try? Rubber gets old, and bad CV boots can cause expensive repairs in comparition to the cost of the boots.
BTW, my understanding is that you can get split boots that can be installed with little effort. Cut the old one off, slip the new one one, and clamp/glue it down. If so it would make CV boots easy to do. This won't work if the old boot is cracked, but if the old one is just worn and you want to replace it before problems start it is a good idea.
I will disagree with you on this point, but I'm not trying to start an arguement. I will agree to disagree because I know many people who will make the case for this. My opinion is that you should do both boots on an axle if one of the boots on an axle is torn. You should not pull the other axle to do the boots on that axle if there is nothing wrong with those boots. If those boots are beginning to show serious signs of wear, then yes, you should do them.
gus
conference host
Mechanic changed the fluid (it was burnt) and cleaned the filter). He said this will extend the life somewhat, but the transmission is on its last legs. He said to put in a new transmission will cost approximately $1,200. Do you think its worth it to put this kind of $ into a car with 163K miles, or is it time to put the old T Bird out to pasture?
Why put a new transmission in? Often you can find a junk yard transmission that will fit, at much cheaper. I'm not sure, but I think a '91 is old enough that a new transmission is a simple fix, relative to other jobs.
All this assumes you care to keep this car, if you are sick of it why put money into it? Note that you won't be able to get much for it without doing transmission work, but can you get that back?
Since your engine is good, you might be able to find someone else who needs that engine to buy the car, and option.
So, what should I do. The engine and trans. is sound, so far. Should I fix it all and keep it until it dies, or should I go out and buy a new one.
You can Re: me at guyle@hotmail.com or here
Thanks for your help
it. Lately I've been hearing a noise coming from
the engine, like spark knock, only louder. I don't
hear it at idle or when decelerating, only on
acceleration or cruise speed. I use 93 octane gas.
Any ideas on the problem?
I hear those Shadows are great little cars. My mom owned a turbocharged one for years and loved it. My suggestion is this: If it's going to cost more to fix the car than it will to buy one as good as your dodge will be when fixed, then Buy. If you can fix yours for less than what you can buy a comperable car, then fix. Personally, I drive cars till they fall apart, duck tape them together again, and drive them some more, but I'm sure everybody is not as madly in love with their cars as I am mine.
dlk9584,
My guess on your knocking problem would be a loose piston rod. Take the oil pan off the bottom of the engine, and make sure all of the rods are firmly attached to the crankshaft. If one is loose, you could probably get away with tightening it up, but to be on the safe side I'd get a service manual and make sure all that knocking hasn't worn anything down to the point where it's out of spec.
Thanks!
saraguigou
trade-in on a new purchase. Both have comparable trade-in value so I am mostly concerned with which car has a better chance of surviving a few years without major expense as my commuting car. The two cars are (1) 1990 Dodge caravan with 2.5 L v4, base model, with 112K miles and (2) 1988 Pontiac Lemans Aerocoupe with 1.6 v4 and 83K miles. They are both in similar condition and similarly maintained. The Pontiac has an oil leak (probably pan gasket) and ac leak.
I am tempted to keep the Lemans due to its lower miles but I have heard nothing good about its reliability. The van is basic and should be cheaper to repair but, with more miles, costly repairs may not be far away. I bought the Lemans new in 1988 and the van used with 75K miles in 1995. The van has had some body accident damage repaired (professionally) at least twice.
Any suggestions?
Thanks.
It is important to remember that if the cost of currently needed repairs + cost of potentially needed future repairs come close to or exceeds the retail value of the auto, it would be wise to consider not repairing. REASON: In the event of an insured loss to the vehicle, the owner will not be able to recoupe all the repair investment. Any repair made just prior to an insured loss will not add an equal value to the auto. Example, rebuilt trans., total cost- $1600.00 will increase the value of the auto aprox. 50% of cost.
Questions that need to be answered: Value of vehicle? current needed repair costs? potential future needed repair costs?
How to anticipate future needed repair costs: There is no sure way to know, but a number of factors will play. Vehicle model, miles, TYPE OF USE (light, normal, severe) & quality of service. Keep in mind the average life of the modern automobile is 100,000 miles, even though there are many we hear of that go much further.
If an owner finds a need for major component repair & wants to know what other major repairs may be around the corner, the best person to talk to is a dependable, honest repair person, or shop owner. Questions to be answered: Eng. fuel mileage? eng. fuel emissions? engine noises? eng. bearings (physical inspection may be necessary)?
eng. oil consumption? trans. shift diagnosis(auto)? drive train condition? brake component condition? steering component condition?
There is no problem with repairing older vehicles at a cost greater then its retail value as long as the owner understands the risk of the event of an insured total damage or theft loss.
See you there!
carlady/roving host