Front Dif issue?

GRN_NVY · #1 04-10-2014, 05:33 AM

Just bought a 94 LS (AWD) and it has a slight/soft knocking noise seemly coming from the front dif. I didn't drive the car very far nor very fast so I really can't offer very much information. The car has been sitting for at least a year and my mechanic says I need to drive it and get the engine good and hot before I take it for emissions testing.

Questions:
1. if it is the dif, does it cost as much or more to rebuild the dif compared to doing the 4 point swap?

2. the noise and knock is not very loud nor is there a heavy thunk, of course I haven't had it on the open road yet. It has no license plate. Do I dare risk driving on the highway without knowing what's actually wrong?

3. one cylinder has some "lifter" noise, how big an issue is that? The mechanic says it could go away after the car is driven a while after the oil has been circulating.

Any and all advice is welcomed ... Give me a shout!

92 SVX · #2 04-10-2014, 06:24 AM

Quote:

Originally Posted by GRN_NVY

Just bought a 94 LS (AWD) and it has a slight/soft knocking noise seemly coming from the front dif. I didn't drive the car very far nor very fast so I really can't offer very much information. The car has been sitting for at least a year and my mechanic says I need to drive it and get the engine good and hot before I take it for emissions testing.

Questions:
1. if it is the dif, does it cost as much or more to rebuild the dif compared to doing the 4 point swap?

2. the noise and knock is not very loud nor is there a heavy thunk, of course I haven't had it on the open road yet. It has no license plate. Do I dare risk driving on the highway without knowing what's actually wrong?

3. one cylinder has some "lifter" noise, how big an issue is that? The mechanic says it could go away after the car is driven a while after the oil has been circulating.

Any and all advice is welcomed ... Give me a shout!

If, and this is just an if, the front diff is bad its way easier/cheaper to replace the entire transmission.

NiftySVX · #3 04-10-2014, 07:56 AM

If it is the front diff then it will go from a light knock to a big time noise and vibration in just a few miles. Make sure it has fluid in it. And if it is a 94 LS it wasn't AWD from the factory so I'd look into what transmission it actually has in it and what ratio.

GRN_NVY · #4 04-10-2014, 12:54 PM

Quote:

Originally Posted by 92 SVX

If, and this is just an if, the front diff is bad its way easier/cheaper to replace the entire transmission.

If it's not the Dif, what else could it be and what is the best way to check it? I've got to get "plates" before I can put it on the road.

Tapani · #5 04-10-2014, 01:00 PM

Does the sound come once per tire rev? It can be many things - brakes, inner/outer CVs, wheel bearing.... Change the oil and look for metal. You can actually see the ring gear teeth thru the level plug.... Small flash light will help. Kind regards, Tapani

GRN_NVY · #6 04-10-2014, 01:04 PM

Quote:

Originally Posted by NiftySVX

If it is the front diff then it will go from a light knock to a big time noise and vibration in just a few miles. Make sure it has fluid in it. And if it is a 94 LS it wasn't AWD from the factory so I'd look into what transmission it actually has in it and what ratio.

Yep, originally FWD car. My knowledge of vehicles doesn't extend much beyond changing belts, plugs and wires and tires. Does the tranny have some Identifying mark I can look for? Does the Dif have a sight glass to check fluid? And finally, if I should decide to do the 4.44 swap, what should the average install cost be, (only to install it) not the cost of the tranny?

Thanx,

svxfiles · #7 04-10-2014, 06:41 PM

Quote:

Originally Posted by GRN_NVY

Yep, originally FWD car. My knowledge of vehicles doesn't extend much beyond changing belts, plugs and wires and tires. Does the tranny have some Identifying mark I can look for? Does the Dif have a sight glass to check fluid? And finally, if I should decide to do the 4.44 swap, what should the average install cost be, (only to install it) not the cost of the tranny?

Thanx,

In a FWD a 4.44 would be a tire smoking bummer of a car to drive.
It could be an axle, easy and cheap to replace.
To convert to AWD you need an AWD trans,
a driveshaft,
an AWD rear subframe,
a rear differential
and a bunch more labor.

GRN_NVY · #8 04-10-2014, 06:59 PM

Quote:

Originally Posted by svxfiles

In a FWD a 4.44 would be a tire smoking bummer of a car to drive.
It could be an axle, easy and cheap to replace.
To convert to AWD you need an AWD trans,
a driveshaft,
an AWD rear subframe,
a rear differential
and a bunch more labor.

It was FWD, but is AWD now. It came to me this way, consequently, I have no idea what was done, how it was done, or even if it were done right. The PO reportedly had just spent nearly 2K on the transmission et al. It does have a front and rear dif, that's all I know.

GRN_NVY · #9 04-10-2014, 07:19 PM

Quote:

Originally Posted by Tapani

Does the sound come once per tire rev? It can be many things - brakes, inner/outer CVs, wheel bearing.... Change the oil and look for metal. You can actually see the ring gear teeth thru the level plug.... Small flash light will help. Kind regards, Tapani

The sound does not seem in sync with tire rotation, and it makes a "flappa-flappa" kind of noise (but starts out as a thunk) that seems to speed up with the engine. Also, there is another noise going on at the same time that sounds(low level noise) like chains grating or being dragged across a metal deck. Sometimes the noise sounds like it's coming from the rear. Now along with these two noises, there is a thunk or knock, especially when just starting out or coming to a stop. Just before coming to a stop there is a big thunk or two which feels like gears dropping in to mesh. I did drive it close to 50 mph but then I started to smell something like hot or burning fluid, so I reduced speed to 35-40. Sometimes it feels like a cv and other times it feels like a van I once had that had a warped drive shaft Oh, and one more thing! At one point when I was driving, the speedometer seem to go haywire (when driving close to 50) but later it seemed to perform correctly when I approached that speed. Engine seems smooth, Sounds Kewul

, and the muffler and pipes sound awesome at speed, and barely noticeable at idle. Umma Luva My Car

GRN_NVY · #10 04-10-2014, 07:31 PM

Quote:

Originally Posted by NiftySVX

If it is the front diff then it will go from a light knock to a big time noise and vibration in just a few miles. Make sure it has fluid in it. And if it is a 94 LS it wasn't AWD from the factory so I'd look into what transmission it actually has in it and what ratio.

You called it brother, it was pretty much as you predicted although the "thump-flappa" noise came after the initial CV type thunk on initial roll, and then the Flappa-Flappa noise sped up but didn't seem to "vibrate as much. The other thing I found interesting was that I had a friend drive it while I stood outside and I could barely hear the noise if at all. But from the inside of the car one could reasonably expect it to explode or dissintegrate at any moment. At least it sounded and felt that way to me when in the drivers seat!

svxfiles · #11 04-10-2014, 07:53 PM

Quote:

Originally Posted by GRN_NVY

It was FWD, but is AWD now. It came to me this way, consequently, I have no idea what was done, how it was done, or even if it were done right. The PO reportedly had just spent nearly 2K on the transmission et al. It does have a front and rear dif, that's all I know.

Can you post the transmission number?
Black letters/numbers on the drivers side bell housing by the starter.

Chucksta · #12 04-10-2014, 08:40 PM

already asked

GRN_NVY · #13 04-11-2014, 01:39 AM

Quote:

Originally Posted by svxfiles

Can you post the transmission number?
Black letters/numbers on the drivers side bell housing by the starter.

Will take a look today after the sun comes up.

92 SVX · #14 04-11-2014, 04:09 AM

Since you do not know any of the details about the AWD conversion you may want to check if the transmission/front diff have the same gear ratio as the rear diff.

GRN_NVY · #15 04-13-2014, 08:00 AM

Quote:

Originally Posted by 92 SVX

Since you do not know any of the details about the AWD conversion you may want to check if the transmission/front diff have the same gear ratio as the rear diff.

Is this something I can do or do I need to take it to a mechanic? Will be taking a good look at the car today. And I'll take some more pics !!!

Thanks everybody, I appreciate all!