This is definitely and OTHER topic...

[Keithmania]

OK, so I have this 1995 Buick Skylark. When you are driving it at highway speeds and hit a bump sometimes it will free rev until the transmission seems to "catch" again. But I am not sure if its the transmission that is slipping or if its a cv joint going bad. Reason I say this is, when it is free revving you can see the speedometer increase as well. I guess if I had a better understand of how the speed sensor works I'd know if its the transmission or a cv joint.

So my question is: if while driving, I hit a large bump or a pothole and then then the engine free revs and I notice the speedometer increase with no increase in actual speed is it a) the transmission slipping or b) a bad cv joint?
tia

 

[Johnnie Walker]

Those are POS anyways, but I would suspect the cv shaft/s

 

[bigalpha]

Is the speed sensor in the CV Shaft?

 

[Johnnie Walker]

Is the speed sensor in the CV Shaft?

Not 100% sure, but I believe that the tone rings are on the outer part of the cv shafts. So yes?

 

[Shorty]

tone ring on the CV shaft should be for ABS sensor. I believe the speed sensor for the vehicle is located in the transaxle.

 

[JohnX]

Yeah, speed sensor is in the Transaxle, right near the axle. I'd suspect a bad axle.

 

[Keithmania]

Thx for the replies, now I just gotta figure out which axle is the culprit.

 

[kastein]

If you had an axle that bad I'd expect it to not go anywhere, unless it's got a limited slip diff. I'd also expect some pretty terrible noises while driving.

But I'm not sure how it can be anything else, because AFAIK the speed sensor has to be after the transaxle internals or the gear it is in will affect its readings... so :dunno:

 

[Keithmania]

Kastein, i agree... I was trying to brain it out but the only time i hear a popping noise is when the car is in reverse. Going forward it sounds completely quiet. I have noticed at highway speeds lately that there is a resonance at 65-70 mph, which also sounds a little on the grinding side of the noise spectrum. At low speeds though, its perfectly quiet. You stomp on the gas pedal and it will spin the tires but doesn't slip or grind...

 

[philagony94xj]

Best way to check is to get the front end up in the air and try moving the cv axle around. If there is excessive play at either end its bad. It doesn't sound like a bad cv axle to me though. My $0.02

 

[87manche]

halfshafts generally make a racket when you go slow and turn the wheel to full lock going forward to reverse on the shifter.

 

[98Eviltwin]

I would suggest checking the shift linkage as it could be bouncing and partially shifting to nuetral when hitting the bump, especially since it is not all the time and not every bump. Just a thought, hope it helps.

 

[Keithmania]

I would suggest checking the shift linkage as it could be bouncing and partially shifting to nuetral when hitting the bump, especially since it is not all the time and not every bump. Just a thought, hope it helps.

That makes sense except that when it starts to slip the speed increases on the speedometer. If it slipped into neutral I would think that just the RPM gauge would indicate a slight rev in the in engine...