Motive 3.90s second thoughts? Come in if you run these gears
 

I'm wanting to swap out the 3.42's in my car. Its an 01 z28 m6. I was strongly considering 4.10's but 3.90s caught my eye for the little longer ratio and strength. My only concern is that the orange box motives have a hit and miss rep for being noisy around here. I dont mind if they whine a little bit at different speeds but i dont want them to howl all the time.

I talked to my buddy who owns his own speed shop and will be doing the install on them. He does rears every day and has done a couple of mine in the past and theyve all been great. He said that the motive orange boxes tend to be a little noisy either from almost silent to being annoyingly loud just hit and miss kinda.

So I'm getting opinions here, he said the 4.10s from gm should be dead quiet but thats a little low for me on the street? I hear 1st gear is too short on the street with them hence why i wanted the 3.90s but if they are prone to noise then I may go 4.10

Thanks!

IMO, bottom line, noisy gears are due to bad install period. All of the motive gears I have installed were 98% quiet and any 2% whine they did generate would be drowned out by the normal whine from the T56 transmission or simple road noise. Its just vital that they be set up right from the start and broken in properly.

For my ride (see sig for specs), 4.11 is too much for normal street tires on the street. Even in the summer when things are warm, they still break loose in first even when you take off quickly without dumping the clutch and I have nice 285 size tires. When I first got my nine inch rear, I had 3.90's and liked them well. I burned those gears up at the track and went with 4.11's which were better at the track but worse on the street. I am looking to go back to 3.90's sometime soon because I very rarely go to the track anyway. With 4.11's, I have to feater the gas to keep it under control in first but the rest of the gears hook great.

All that said and speaking to the street, if your making near 400RWHP, I would go 3.90's. If you have closer to stock power, then 4.10's and 4.10's all day long at the track.

My two cents.

thanks for the reply, i trust him completely on being able to install hte gears correctly as I've known him forever and hes done multiple rear ends that have been dead quiet, he just recommended i dont go with the orange boxes as they do produce some whine, and it looks like people on here have had similar issues. the car does make 390whp fwiw. even with 3.42's and bfg 295's out back i cant roll into first gear without breaking them loose

3.90's rock. I have them for years now. Alot stronger than 4.10 also. I went from breaking ring gears with 4.10 to breaking axles with 3.90's. I never have liked a 4.10 in these cars. I would do 3.73 before 4.10.

I have the motive 3.90's in my 10 bolt with the torsen differential. I love the performance of the gears. I installed the gears. The pattern and backlash were both RIGHT! The gears have a slight whirr on the coast side. My friend who is the best said he's had this happen with the motives. I've run them for 14k miles now and the noise has never gotten worse or better. You really can't hear it unless you know what you're listening for. I've ran 3.90's in my last couple f-body's. Your buddy is right about 1st being to short with the 4.10's and stock tires.

I agree hence why I really dont want to do 4.10's. I dont feel 3.73 is a big enough jumpt o justify the cost of the install though.
thanks man is it just at a particular speed or is it all around? and would you say its audible in normal driving or do you really need to listen for it.

i toasted the gears in this one once and i just had a set of used 3.42's laying around so i had my buddy install them. thinking they were blind used gears from a bone yard i thought they'd be noisy... he did an awesome job, and i only have a small hint of whine from 60-65 so i have complete confidence in his install abilities. i dont have a spare rear so i just didnt want to be screwed if this went south but its good to hear people dont have whine.

My noise is at around 40-50 mph and only coasting, as soon as you push the pedal it disappears. Like I said, you really can't hear it but its there. I'm satisfied with them.

OP, I went through the same 3.90 vs 4.10 decision as you and I chose AAM 4.10s. My AAM gears are quiet except for a slight whine in the unloaded transition from drive to coast. At your power level 3.90s would be a nice street gear, although traction in first still won't be good. I would avoid DRs at the track with the M6 and 10 bolt with either ratio though. IMO wrd1972 nailed it with his response.

3.73 is ALOT bigger jump than most give it credit for. If you have other bol-ons or plan more bolt-ons it don't take long before your out of gear with 4.10's. Hears the gear break down.

RPM 1st 2nd 3rd 4th 5th 6th Gear
500 3 5 7 9 13 19
600 4 6 9 11 15 22
700 5 7 10 13 18 26
800 6 8 11 15 20 30
900 6 9 13 17 23 34
1000 7 10 14 19 25 37
1100 8 12 16 20 28 41
1200 8 13 17 22 30 45
1300 9 14 19 24 33 48
1400 10 15 20 26 35 52
1500 10 16 21 28 38 56
1600 11 17 23 30 40 60
1700 12 18 24 32 43 63
1800 13 19 26 34 45 67
1900 13 20 27 35 48 71
2000 14 21 29 37 50 74
2100 15 22 30 39 53 78
2200 15 23 32 41 55 82
2300 16 24 33 43 58 86
2400 17 25 34 45 60 89
2500 17 26 36 47 63 93
2600 18 27 37 48 65 97
2700 19 28 39 50 68 101
2800 20 29 40 52 70 104
2900 20 30 42 54 73 108
3000 21 31 43 56 75 112
3100 22 32 44 58 78 115
3200 22 33 46 60 81 119
3300 23 35 47 61 83 123
3400 24 36 49 63 86 127
3500 24 37 50 65 88 130
3600 25 38 52 67 91 134
3700 26 39 53 69 93 138
3800 27 40 54 71 96 142
3900 27 41 56 73 98 145
4000 28 42 57 74 101 149
4100 29 43 59 76 103 153
4200 29 44 60 78 106 156
4300 30 45 62 80 108 160
4400 31 46 63 82 111 164
4500 31 47 64 84 113 168
4600 32 48 66 86 116 171
4700 33 49 67 88 118 175
4800 34 50 69 89 121 179
4900 34 51 70 91 123 182
5000 35 52 72 93 126 186
5100 36 53 73 95 128 190
5200 36 54 74 97 131 194
5300 37 55 76 99 133 197
5400 38 56 77 101 136 201
5500 38 58 79 102 138 205
5600 39 59 80 104 141 209
5700 40 60 82 106 143 212
5800 41 61 83 108 146 216
5900 41 62 85 110 148 220
6000 42 63 86 112 151 223
6100 43 64 87 114 153 227
6200 43 65 89 115 156 231

If your just doin bolt-ons you are past your peak power @ 102 mph......that sucks.

Fyi me and buddy got his mild bolt-on car to go 11.96 @ 116mph with 3.73's and a 1.75 60'. Car don't even have headers and only about 200# of weight out.

thanks for all the replys guys i currently make 390 through the m6 its got a cam. nothing too crazy though. that's another reason I shyed away form 4.10's not only are they weaker for a car making almost 400whp but traction on the street would be almost nothing. since i'm paying to have the install done i didnt want to do 3.73's especially with my power band i just didnt think it would be worth it. i'm leaning towards 3.90s still. as long as the setup is good they should be quiet? my buddy doesnt install a lot of motive hence why he wasnt sure about te orange boxes but he has done thousands of other rears, including 2 of my own with used oem gears and they have been near dead silent even after being transplanted from another rear

FWIW, I have Motive orange box 3.73's and they have been silent since they were installed a few years ago. I jumped from 3.23's to these back when the car was an auto, but I still liked them after the M6 swap.

thanks man were they hard to setup or did everything go smoothly?

Just casue they are orange box makes them no different to set up than any other gear. They all set up the same and require the same attention to detail.

If you want the quietest gear possible, find the AAM (American Axle) gears. A good while back, the Randys Ring and Pinion Yukon gears were reboxed AAM gears. They were very quiet but a bit less strong compared to Motive OB gears.

I would go with them if I wanted to do 4.10s, I drove my buddies at yesterday with 4.10s and they're just a little short for my taste. I don't mind if I have some small wine at a certain speed I just don't want them loud all the time like some Richmond setups I've heard. As long as they're setup properly they should be mostly quiet correct? Sorry for the been questions I just want to be thorough as its a permanent thing lol

Love my 3.90 motives.

Ive had both 4:10s and 3:90s. Both are great with a 6 speed but I like the 3.90s better. I think 4:10s would be too much if I ever wanted to supercharge my 6.0 or stroke it to a 408 and make serious power so i decided on 3:90s.

My uncle set up mine, he works at a Jeep dealership and has lots of experience doing it. The only issue he ran into was the rebuild kit I had provided him (Ratech) did not have the right sized shims for the carrier. But he found that reusing my factory shims worked perfectly.

I have Motive 3.90 in my M6. I installed them myself about six months ago with no issues. I used new bearings to ensure after the install I would not have any noise. And yes some kits the have shims may not get you to the backlash you need. I was able to get .007 with the what was in the kit. This was Motive MGR-R75GRSKT. When I restored my Camaro I should have did it then, because I installed LS1 rear brakes which required for me to use LS1 axles. Anyway, I was just like you not knowing what to go with 4.10 or 3.90. After reading alot of post my thoughts were like this. If I spent the money to install 4.10's and I brake them because they are not strong enough I would be pissed off. I also like to drive at highway speeds. In Florida 80 just to keep up with traffic. I know the they did make a big difference with a hotcam and LT4 heads. I did have some problems getting the speed calibrated correctly. I have JET DST tuner for this and I had to make adjustments a little at a time. Just my two cents. Hope this helps.

I run 4.11 gears in my 9", and it's not too much on the street, in my opinion. I actually love it. You will need sticky tires though, but I don't think the gear is too short at all.

What's your rpm range and tire height Hollo?