Frustrated by diff gear noise!
Thread Starter
Melting Slicks
Joined: Jun 2002
Posts: 2,168
Likes: 16
From: Phoenix AZ
Frustrated by diff gear noise!
I think I hold the record for taking the differential out of my '86 the most times. This should be a once-in-a-lifetime job, but not for me.
It began when I replaced the stocker with a 3:73 to work better with my ZF 6-speed conversion. Well, let me tell you that if you have heard that 3:73's are too steep for the L98, you have heard right. I decided to get an exchange unit (and in all fairness, until I find out for sure what the problem is I won't say from who) with a 3:45 ratio. The exchange unit had all new internals and was pre-lapped.
Here's where things went terribly wrong. I loved the 3:45 ratio, but I had an annoying gear whine at 25 mph and 45 mph. I reluctantly pulled the diff back out and shipped it back to the shop it came from (clear across the country, incidentally) only to hear back that the wear pattern was normal, the pinion backlash and gear mesh were correct, and running it on the test equipment produced no noise at any speed. Nevertheless, the unit was completely torn down and inspected, set deeper in mesh to limit harmonics, reassembled, and tested again. Then it was shipped back to me.
In the meantime, I had replaced all U-joints, from the driveshaft to the half-shafts. The car has new GM wheel bearings, all new bushings, and new shocks. I reinstalled the differential last night and took the car out on the road. Same noise, only lower in pitch and at a slightly higher speed. Time to break out the gasoline and matches so I can collect the insurance and be done with it. Seriously, I love my car but am frustrated as anyone would be in this situation. Anyone got any ideas out there? It definitely sounds like it is coming from the differential, although sound can be transmitted through the driveshaft. Please help!
(Picture is of car on jacks because this is how it spends 99% of its time)
It began when I replaced the stocker with a 3:73 to work better with my ZF 6-speed conversion. Well, let me tell you that if you have heard that 3:73's are too steep for the L98, you have heard right. I decided to get an exchange unit (and in all fairness, until I find out for sure what the problem is I won't say from who) with a 3:45 ratio. The exchange unit had all new internals and was pre-lapped.
Here's where things went terribly wrong. I loved the 3:45 ratio, but I had an annoying gear whine at 25 mph and 45 mph. I reluctantly pulled the diff back out and shipped it back to the shop it came from (clear across the country, incidentally) only to hear back that the wear pattern was normal, the pinion backlash and gear mesh were correct, and running it on the test equipment produced no noise at any speed. Nevertheless, the unit was completely torn down and inspected, set deeper in mesh to limit harmonics, reassembled, and tested again. Then it was shipped back to me.
In the meantime, I had replaced all U-joints, from the driveshaft to the half-shafts. The car has new GM wheel bearings, all new bushings, and new shocks. I reinstalled the differential last night and took the car out on the road. Same noise, only lower in pitch and at a slightly higher speed. Time to break out the gasoline and matches so I can collect the insurance and be done with it. Seriously, I love my car but am frustrated as anyone would be in this situation. Anyone got any ideas out there? It definitely sounds like it is coming from the differential, although sound can be transmitted through the driveshaft. Please help!
(Picture is of car on jacks because this is how it spends 99% of its time)
Team Owner
Joined: Apr 2000
Posts: 27,818
Likes: 8
From: CT
Noise
If it'll make you feel any better...My Dana 44 has a slight whine around 45 or so...On the highway, there is a little vibration in the rear as well.
Red96Coupe just had His rear re-done earlier this season...I Went for a ride in it last week, and He has the same highway vibration as I do. I have no idea the mileage my 44 has, it came out of a ZR-1. My 36(Along with red 96's) had the vibration also. I've changed all u joints etc. Still there.
I have heard, due to the beefier construction of the 44's they'd be tad noisier. My 36 was silent except for the vibration at speed.
Hope that made some sense, and try not to let it get to you too much.
Red96Coupe just had His rear re-done earlier this season...I Went for a ride in it last week, and He has the same highway vibration as I do. I have no idea the mileage my 44 has, it came out of a ZR-1. My 36(Along with red 96's) had the vibration also. I've changed all u joints etc. Still there.
I have heard, due to the beefier construction of the 44's they'd be tad noisier. My 36 was silent except for the vibration at speed.
Hope that made some sense, and try not to let it get to you too much.
Drifting
Joined: Apr 2002
Posts: 1,451
Likes: 0
From: Owensboro Ky
Re: Frustrated by diff gear noise! (vetracer)
If you have pulled it more than 6 times, then you have me beat. I sent my back too because of a leaking front yoke seal and a high pitch squeal. JUst got it back in yesterday and finally got it broke in today. The noise is still there but not as bad. I mainly hear it between 25-35 mph and it stops when I turn a corner. But I can learn to live with it since it now turns the tires over at a 30mph punch. Sure made my car alot more fun to drive even if I am going through tires faster. :smash:
I forgot to mention that I went from a 2.59 to a 3.54. To hell with gas mileage! :lol:
[Modified by ZAD54, 6:52 PM 9/13/2002]
I forgot to mention that I went from a 2.59 to a 3.54. To hell with gas mileage! :lol:
[Modified by ZAD54, 6:52 PM 9/13/2002]
