Let's Talk Rear End Gears!
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From: Lincoln, Nebraska
Let's Talk Rear End Gears! Hey everyone,
Sorry for another thread but I had a few more questions. I know I recently talked about wanting some suspension parts but I think I can get more bang for my buck possibly by putting in some rear end gears. I know there is alot of brands - AAM, Motive, Richmond, Strange etc etc. I have researched that AAM are the overall best brand to get? Do you guys agree, and if so where would be the best place to buy them? Also is our rear ends the 8.5in size I know its a 10 bolt. Now I have an A4 and it maybe sees the highway a couple times a year, put about 1k or so a year on my car. Car has - LT's, ORY, CAI, STB, SFC's, Nitto NT05R's out back. Which size gear would you recommend? I was always thinking 3:73's but I've recently been itching for possibly 4:10's. Car has the stock ten bolt that was replaced at 20k due to a factory issue. Should I upgrade my axles at the same time? I did some google searching and some suggest this to be done at the same time. I have the GU2 code on my DS door so thats a series 2 carrier in my rear end if I'm not mistaken. I would have to have these installed, see most prices to be about $175-$250?
Devin
Sorry for another thread but I had a few more questions. I know I recently talked about wanting some suspension parts but I think I can get more bang for my buck possibly by putting in some rear end gears. I know there is alot of brands - AAM, Motive, Richmond, Strange etc etc. I have researched that AAM are the overall best brand to get? Do you guys agree, and if so where would be the best place to buy them? Also is our rear ends the 8.5in size I know its a 10 bolt. Now I have an A4 and it maybe sees the highway a couple times a year, put about 1k or so a year on my car. Car has - LT's, ORY, CAI, STB, SFC's, Nitto NT05R's out back. Which size gear would you recommend? I was always thinking 3:73's but I've recently been itching for possibly 4:10's. Car has the stock ten bolt that was replaced at 20k due to a factory issue. Should I upgrade my axles at the same time? I did some google searching and some suggest this to be done at the same time. I have the GU2 code on my DS door so thats a series 2 carrier in my rear end if I'm not mistaken. I would have to have these installed, see most prices to be about $175-$250?
Devin
they are 7.5 inches and the gu2 rpo code from your door jam doesnt mean its the series 2 carrier its the gear ratio type, i think thats a 323 gear so it would be a 3 series i believe.aam is the gear you want to go with
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From: Hastings, Nebraska
im running motives. they whine a little around 55-60 but otherwise there quiet
If you drive the car on the highway your probably gonna want to stick with 3:73's my car is 2500 at 65mph with them and just under 3k at 80
If you drive the car on the highway your probably gonna want to stick with 3:73's my car is 2500 at 65mph with them and just under 3k at 80
On the other hand, my 5.18's on my Chevelle make it to the stop sign at the end of my street.
Being old, and not liking excess noise (like to listen to XM- Sirius 50s on 5 in peace) I much prefer GM gears. The S10 pickups share the same ring & pinions.
Therefore quiet 3.73 & 4.10 gears are available at the GM dealer's parts depts.
Therefore quiet 3.73 & 4.10 gears are available at the GM dealer's parts depts.
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With your tire size 3.73 at 70mph is 2600rpm.
With 4.10s it would be about 2800rpm.
Stock with your tire is about 2200rpm.
As a M6 with 3.24s same tire is about 1700rpm.
3.73s is 1800rpm.
4.10s is about 2000rpm.
So you can see why the M6 is better with a 4.10 because of the 5/6th gear.
A4 you should just run a stall and 3.73s unless you want a strip monster.
With 4.10s it would be about 2800rpm.
Stock with your tire is about 2200rpm.
As a M6 with 3.24s same tire is about 1700rpm.
3.73s is 1800rpm.
4.10s is about 2000rpm.
So you can see why the M6 is better with a 4.10 because of the 5/6th gear.
A4 you should just run a stall and 3.73s unless you want a strip monster.
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Joined: Jan 2013
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From: Las Vegas
Okay lets talk (and u can do the buying). The stock GM gears are actually the highest quality gear sets. The problem with the 7.5" gear sets is they are small material wise and don't handle as much strength as 8.5" 10 bolt or 8.875" 12 bolt rears. And as the ratio increases the number of teeth increase and then the size of teeth decrease - yep the teeth get weaker as ratio increases. So if your starting with a small gear set already increasing the ratio weakens it more.
FWIW my '94 with an A4 has 3.23 gears and makes too much wheel spin to drag race with street tires. When i put on the MT drag radials i have to use the water box to hook up - otherwise still too much wheel spin. Using drag radials and the water box is 'bout right for my mostly stock LT1 (only headers). I don't know how others are launching using 3.73 gears or higher.
As far as positraction goes im running the stock posi but have read the torsen posi is better.
Now for axles i had Yukon axles installed (well because i had a bent axle and thats what the shop recommended/installed) but i have read Yukon axles have a great reputation especially with the off road crowd.
BTW something the off-road crowd uses is cryogenic treatment of the gear sets - something the drag race crowd doesn't bother with. I got to ask a Moser rep at the drag strip once and he said something like cryo treat increases load strength but doesn't handle the snap loading of drag racing - don't know if he made it up or not so take it or leave it. But a weak gear set needs all the help it can get and the ring/pinion is the weak link of the 7.5" 10 bolt. And cryo treat is cheap - nothing compared to cost of installing a 12 bolt.
Okay thats everything,
cardo
FWIW my '94 with an A4 has 3.23 gears and makes too much wheel spin to drag race with street tires. When i put on the MT drag radials i have to use the water box to hook up - otherwise still too much wheel spin. Using drag radials and the water box is 'bout right for my mostly stock LT1 (only headers). I don't know how others are launching using 3.73 gears or higher.
As far as positraction goes im running the stock posi but have read the torsen posi is better.
Now for axles i had Yukon axles installed (well because i had a bent axle and thats what the shop recommended/installed) but i have read Yukon axles have a great reputation especially with the off road crowd.
BTW something the off-road crowd uses is cryogenic treatment of the gear sets - something the drag race crowd doesn't bother with. I got to ask a Moser rep at the drag strip once and he said something like cryo treat increases load strength but doesn't handle the snap loading of drag racing - don't know if he made it up or not so take it or leave it. But a weak gear set needs all the help it can get and the ring/pinion is the weak link of the 7.5" 10 bolt. And cryo treat is cheap - nothing compared to cost of installing a 12 bolt.
Okay thats everything,
cardo
If you have 3.73s in an auto, drop from OD to D and that is just about the same gearing as 4.10s in OD would feel like. It's not as dramatic as some people make it out to be.
Not a huge RPM/MPG difference, so if you go to the track more then once or twice a year I would go 4.10s. With you only putting 1k a year on your car I don't see a reason to not go 4.10s unless you are making tons of power since they are weaker and harder to launch with.
Autos are easier on the rear end then manuals but I still wouldn't bother with upgrading the 10bolt unless its just a street car or you don't plan a lot of heavy mods. If you take it to the track often, may as well start saving for a 12bolt.
Not a huge RPM/MPG difference, so if you go to the track more then once or twice a year I would go 4.10s. With you only putting 1k a year on your car I don't see a reason to not go 4.10s unless you are making tons of power since they are weaker and harder to launch with.
Autos are easier on the rear end then manuals but I still wouldn't bother with upgrading the 10bolt unless its just a street car or you don't plan a lot of heavy mods. If you take it to the track often, may as well start saving for a 12bolt.
Sorry for the off top
Go with 4.10s. They are great and tons of fun on the street. A properly set up rear end shouldn't make noise. I drive mine on the highway everytime I take it out. 80mph is about 3100rpms. I don't mind the noise. I'm running a 285/40/18 tire.
Gears aren't as big of a performance upgrade as many will lead you to believe. I'd personally put the cash towards a fab 9" or 12 bolt, and choose whatever gear ratio you want (for no added cost usually) when you order a new rear end.
Mine is set up properly and it makes noise. They are cheap gears though...
The best bang for the buck would be a stall.
But as i have had both 4.10 and 3.73's i would say 3.73's is a really good gear. But ive been thinking about putting 3.90's in... so your choice. I will say that the 4.10's were awesome at making me buy new tires all the time.
But as i have had both 4.10 and 3.73's i would say 3.73's is a really good gear. But ive been thinking about putting 3.90's in... so your choice. I will say that the 4.10's were awesome at making me buy new tires all the time.
I had a set of 3.73 in my nova with an A4 and they made a great street strip setup with 26" tires. On the other hand i have summit brand 4.10s in the camaro with an m6. Very fun and made no noise untill they started getting beat on. They eventually stripped the pinion teeth but was my fault. (DR's at the track)
If you cruse your car more than let it rip id say get the 3.73. If you let it rip go 4.10. Im running 4.56 in the nova now with the same a4 and 26" tires. Yeah she screams on the highway but at, like you, ~1000 miles a year its alot fun at the track or street.
If you cruse your car more than let it rip id say get the 3.73. If you let it rip go 4.10. Im running 4.56 in the nova now with the same a4 and 26" tires. Yeah she screams on the highway but at, like you, ~1000 miles a year its alot fun at the track or street.