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| Subject |
first set: 8, second set: 7, third set: 7 stock bushings |
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| Posted by |
TTkeeper on April 20, 2009 at 12:53 AM |
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This message has been viewed 146 times. |
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| In Reply To |
4.10 ("Leadergears") feedback re: gear whine. I am posted by SirpriZ on April 19, 2009 at 08:59 PM |
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| Message |
As you can read in the subject line, I've been on a quest to get a quiet set since the gears were first available. (I'm not the only one). My first set was from the first production run and were set up locally by a diff tech with 20 yrs experience. They were loud (wail) and Mark graciously worked with me on an exchange for a set from the second production run. The second set were set up by SpecialtyZ's diff man ( Russ, I believe ) with new bearings and of course the new ring/pinion. After the install, I immediately noticed the same wail...quieter than the first set from 0 to 59 mph ( I have the corrected speed sensor gear so these speeds are pretty accurate ) but nearly the same between 60 and 70 mph. At those 60-70 speeds the whine is present on accel, cruise, and coast. I have the OEM gel filled bushings and lots of dynomat in the trunk.
My third set came with a differential that I purchased from a twinturbo dot net member through the classified section...He too had an experienced shop set up his. He assured me they were not dead quiet but tolerable ( probably a 5 on our scale here ). When I received the diff, I swapped entire differentials and noticed the whine right away. It was about the same as my second set...annoying, louder than the stereo at normal listening volume, and especially prominent between 60-70 mph. I love the ratio, but don't enjoy the noise.
So here is my assessment...and I'm not a metallurgist. Likely the problem is the metal alloy the gears are made of. The stronger the alloy, the less give, & the more noise. But this theory breaks down in two areas: 1) some people have achieved a quiet setup & 2) factory Ferraris, Mustang Cobras, BMW M3s have as many hp as our modified Zs and they don't whine. So that leaves us with the setting-up of the gears. Keep in mind that most diff rebuild shops don't have the kind of precision machinery that the diff maker ( like Dana Corp ) has. The reason factory diffs don't whine is because they have $500,000 machines doing the assembly and fine tuning, statistical quality control and testing, and computer precision.
The only way an independent shop is going to get the setup perfect is by trial and error ( and this isn't a slam against them..they just don't have the car to listen to it on). These guys just go by a wear pattern and experience. Unfortunately, its hard to duplicate the loading the actual car is going to put on those gears. So you just have to dismount the diff, tear into it again, adjust the shims, re-install it, then listen to it again. This can get very expensive if you are paying someone to take it off, paying two-way shipping, paying a tech to re-build it again, paying to have it re-installed...and hoping all the while that a wear pattern hasn't gotten started that you can't reverse. I love the gears, the ratio, and the torque benefit...I just wish it wasn't so hard to get a quiet setup. I too use the recommended Richmond gear oil and observed all the break-in guidelines. Maybe a different alloy, good for 550 rwhp, would allow the shops a little more wiggle room on the setup and might produce a quieter differential. Thanks Mark for asking for our input...its a great product...and as with any mod, there are going to be changes from what we were used to that we'll have to live with.
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22:58:50 04/19/09
