350evo 3.9FD install questions
01-30-2006, 05:11 AM
#21
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Originally Posted by fairladyZ in Japan
There is small whining takes place on many 3.9 FD's .. around 55-70 mph if my memory is correct. Perfectly normal, to my understanding .. I have it.
I have a friend who got his 3.9 about two months before I got mine and he has absolutely no whine. It sounds just like stock. The 3.9 was installed at the same place and by the same tech on both cars. The only differences are that my car is an 03 and his is an 04. We both have stock LSDs and we both replaced the same parts. Go figure.
01-30-2006, 12:31 PM
#22
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I just talked to a driveline shop (different from the ones that installed my gears) and even the tech told me that the gears do not need to be broken into and there shouldn't be any noise. I am taking it in to that shop tomorrow to get their opinion on the matter.
01-30-2006, 11:01 PM
#23
Originally Posted by ZPirate
The whining sound on mine becomes audible at about 35mph. It is very noticable in 5th at about 45 to 55 mph.
I have a friend who got his 3.9 about two months before I got mine and he has absolutely no whine. It sounds just like stock. The 3.9 was installed at the same place and by the same tech on both cars. The only differences are that my car is an 03 and his is an 04. We both have stock LSDs and we both replaced the same parts. Go figure.
I have a friend who got his 3.9 about two months before I got mine and he has absolutely no whine. It sounds just like stock. The 3.9 was installed at the same place and by the same tech on both cars. The only differences are that my car is an 03 and his is an 04. We both have stock LSDs and we both replaced the same parts. Go figure.
but there are different sounds you get from a mis-install...
You can have a howling or wining from a bearing that has been re-used and when it was pulled off and pressed back on somehow got damaged.
If the shims are set too tight then you have a sound...
If the shims are set too loose then you have a sound...
the tools required to measure the tollerances are very expensive :-/
There are shops that do ONLY rear ends... There is only one gear shop local to us that I recommend...
02-01-2006, 03:41 PM
#24
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I talked to a shop that Jason recommended me to and the conversation led me to a pretty unfortunate place. According to the guy I talked to, since I've been driving on these gears for as long as I have (yea, it's my daily driver) it could easily at this point become impossible to figure out how to properly line them up, assuming that they were that far out -- and my installer may have basically cost me the that gear set. So, it sounds like if they can't get it right then I'm SOL.
02-08-2006, 06:44 PM
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After a long process basically I am in the same situation. I went to a second shop (well-experienced driveline shop) to get a second opinion seeing I was getting no results with my initial installer. They took it apart at the second shop and found the backlash to be too tight. They said it was set at 5 which it should be set 7-10 for these gears. Unfortunately the result is the same situation that rgreene is in.
02-09-2006, 05:59 AM
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Here is a great thread that was posted last year .. a review of the 350EVO 3.9 FD that was installed by 350EVO. T
The review addresses backlash .. and some whine you can expect.
https://my350z.com/forum/showthread....ight=3.9+whine
The review addresses backlash .. and some whine you can expect.
https://my350z.com/forum/showthread....ight=3.9+whine
02-09-2006, 07:55 AM
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Originally Posted by fairladyZ in Japan
Here is a great thread that was posted last year .. a review of the 350EVO 3.9 FD that was installed by 350EVO. T
The review addresses backlash .. and some whine you can expect.
https://my350z.com/forum/showthread....ight=3.9+whine
The review addresses backlash .. and some whine you can expect.
https://my350z.com/forum/showthread....ight=3.9+whine
02-09-2006, 09:12 AM
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The noise that I'm hearing is well above what is normal. When maintaining speed on the freeway it is a very loud droning, enough so that you have to talking much louder to be able to be heard by your passenger. The shop that I went to was ordering some new shims, but that was weeks ago... I'm starting to get a bit pissed off, and am wondering if they are avoiding me. Does anybody else know another shop here in Southern California that could take a look at it? I talked to Performance Gearing in Irwindale, but they told me that they can't help me due to how long I've been running the gears already (not to mention they would require that my rear diff was already seperated from my Z). I'm going to call the shop today or tomorrow and get an update on the shims, if I get the feeling that they are blowing me off, do I have any recourse with my credit card company?
02-09-2006, 11:12 AM
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Some whine is something I suppose I would live with but like rgreene this is a high pitched whine. Even if I have my radio up full blast and windows down, I can still hear it! I am going to get a new set of gears and make sure that the install is exact! Only thing that was wrong with my install was the backlash being too tight. I will post more info. as they come, right now working on getting new gears.
02-09-2006, 12:38 PM
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Originally Posted by VegasZ35TH
Some whine is something I suppose I would live with but like rgreene this is a high pitched whine. Even if I have my radio up full blast and windows down, I can still hear it! I am going to get a new set of gears and make sure that the install is exact! Only thing that was wrong with my install was the backlash being too tight. I will post more info. as they come, right now working on getting new gears.
Vegas - The noise level you & rgreene are mentioning is, as you both state, unacceptable. I can tell you this....if this exaggerated level of "whine" is due to the gear's backlash being too tight, it's REALLY tight - it's probably worn a bit as well...maybe too much to shim correctly. Normally, the "RPM whine" that is spoken about with the 3.9 (usually shows itself only between 3-4.5k RPM) is due to the backlash being set a little loose (as I mentioned before - to run a little cooler in the diff housing). I suppose if the backlash was set a little too tight it would whine as well (and run very hot!), but the noise level you're talking about is InSaNe!!!
Best of luck getting things worked out - both of you!! Keep us filled in......
02-09-2006, 12:45 PM
#31
besides the noise, you are also adding resistance in the gearing so more force needs to be used to turn the gear...
as Z Cruzn mentioned, you are creating additional heat, strain on the bearings etc etc... basicly, all the parts that are touching the pinion gear are toast... Bearings, etc...
over time, differentials fail, but yours will fail sooner most likely...
as Z Cruzn mentioned, you are creating additional heat, strain on the bearings etc etc... basicly, all the parts that are touching the pinion gear are toast... Bearings, etc...
over time, differentials fail, but yours will fail sooner most likely...
02-09-2006, 08:04 PM
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Originally Posted by JDMFairlady21
wow this gives me something to think about before messing with my FD. jason or anyone else have experience with the central 20 kit?
The cause of the problem is not the part -- but getting the installation correct from the start with a skilled installer.
02-10-2006, 08:38 AM
#37
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Originally Posted by Jason@Performance
We install pretty much everything except ring and pinions..
One of the tools required for the install is around $12K USD they tell me... :-/
One of the tools required for the install is around $12K USD they tell me... :-/
), I really don't want to have to drive the car to CA again.
02-14-2006, 03:13 PM
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This is also in my future so this sounds a little scary. I will have the guys that Performance reccomend do it for sure. Any way, I had a question. If I am in 5th gear at 4k rpm I am going 87mph. Once I install the 3.9FD, how will this change?
Fill in the blank:
3.5 in 5th @ 4k rpm=87mph
3.9 in 5th @ 4k rpm=
Fill in the blank:
3.5 in 5th @ 4k rpm=87mph
3.9 in 5th @ 4k rpm=
02-14-2006, 03:15 PM
#39
there is a formula....
OK, So you want to know how what speed you will be going in at different RPM's with different gearing... Well here is how to do it with a simple math equation...
(yes wat we learnded in skool wuz gud 4 sumting)
First thing we need to do is figure out how many times your tire size will rotate per mile.
A simple tool to use...
Tire Size Calculator:
Stock Tire Size (245/45/18) will rotate: 756 Times per mile
Here is the equation...
RPM / Final Drive Gear / Tire RPM x 60 = Speed
Example in 5th Gear on a 6MT (1:1):
Example in 4th Gear on a 5AT (1:1):
3000RPM / 3.538 FD / 756 TRPM x 60 = 67.3 MPH
3000RPM / 3.917 FD / 756 TRPM x 60 = 60.8 MPH
3000RPM / 3.357 FD / 756 TRPM x 60 = 70.9 MPH
If you wanted to see what you would be doing at say 5000 RPM in 2nd gear here is how to figure that:
First you must find the gear raito for 2nd gear: 2.324
Multiply FD size by 2nd gear ratio: 3.538 x 2.324 = 8.22
8.22 is now the overall final drive ratio to the wheels...
Here is an exmaple of 5000 RPM in 2nd Gear with a 6MT trans:
3000RPM / (3.538 FD x 2.324 G = 8.22) / 756 TRPM x 60 = 28.9MPH
3000RPM / (3.917 FD x 2.324 G = 9.10) / 756 TRPM x 60 = 26.2MPH
3000RPM / (3.357 FD x 2.324 G = 7.80) / 756 TRPM x 60 = 30.5MPH
Gear Ratio for 6MT Transmission:
1st: 3.794
2nd: 2.324
3nd: 1.624
4th: 1.271
5th: 1.000
6th: 0.794
So for fun lets do one more:
6th Gear in 6 speed manual car at 7200RPM:
7200RPM / (3.538 FD x 0.794 G = 2.80 FD) / 756 TRPM x 60 = 204.08MPH
7200RPM / (3.917 FD x 0.794 G = 3.11 FD) / 756 TRPM x 60 = 183.73MPH
7200RPM / (3.357 FD x 0.794 G = 2.66 FD) / 756 TRPM x 60 = 214.82MPH
OK, So you want to know how what speed you will be going in at different RPM's with different gearing... Well here is how to do it with a simple math equation...
(yes wat we learnded in skool wuz gud 4 sumting)
First thing we need to do is figure out how many times your tire size will rotate per mile.
A simple tool to use...
Tire Size Calculator:
Stock Tire Size (245/45/18) will rotate: 756 Times per mile
Here is the equation...
RPM / Final Drive Gear / Tire RPM x 60 = Speed
Example in 5th Gear on a 6MT (1:1):
Example in 4th Gear on a 5AT (1:1):
3000RPM / 3.538 FD / 756 TRPM x 60 = 67.3 MPH
3000RPM / 3.917 FD / 756 TRPM x 60 = 60.8 MPH
3000RPM / 3.357 FD / 756 TRPM x 60 = 70.9 MPH
If you wanted to see what you would be doing at say 5000 RPM in 2nd gear here is how to figure that:
First you must find the gear raito for 2nd gear: 2.324
Multiply FD size by 2nd gear ratio: 3.538 x 2.324 = 8.22
8.22 is now the overall final drive ratio to the wheels...
Here is an exmaple of 5000 RPM in 2nd Gear with a 6MT trans:
3000RPM / (3.538 FD x 2.324 G = 8.22) / 756 TRPM x 60 = 28.9MPH
3000RPM / (3.917 FD x 2.324 G = 9.10) / 756 TRPM x 60 = 26.2MPH
3000RPM / (3.357 FD x 2.324 G = 7.80) / 756 TRPM x 60 = 30.5MPH
Gear Ratio for 6MT Transmission:
1st: 3.794
2nd: 2.324
3nd: 1.624
4th: 1.271
5th: 1.000
6th: 0.794
So for fun lets do one more:
6th Gear in 6 speed manual car at 7200RPM:
7200RPM / (3.538 FD x 0.794 G = 2.80 FD) / 756 TRPM x 60 = 204.08MPH
7200RPM / (3.917 FD x 0.794 G = 3.11 FD) / 756 TRPM x 60 = 183.73MPH
7200RPM / (3.357 FD x 0.794 G = 2.66 FD) / 756 TRPM x 60 = 214.82MPH