Rear end gear help

3306 Views 37 Replies 6 Participants Last post by S.Humrich, Jul 16, 2012

S.Humrich

Discussion Starter · Jul 6, 2012

I have 370 gears and a 4L60E transmission with 17" wheels. On freeway at 80mph I'm spinning 2800 rpm's. My gears are noisy and I'm thinking about switching but wondered if I went with 350 gears would it make that much of a difference or should I think about lower in the 3's. For those that don't know me, my car is a street car not built for racing. I have plenty of power and the rear wheels spin with ease in fact they spin to easy which is another reason I want to change my gears. Any suggestions will help.

Thanks
Steve

1 - 20 of 38 Posts

MBZTECH

· #2 · Jul 6, 2012

Steve check this web site out. RICK
http://www.angelfire.com/fl/procrastination/rear.html

S.Humrich

Discussion Starter · #3 · Jul 6, 2012

MBZTECH said:
Steve check this web site out. RICK
http://www.angelfire.com/fl/procrastination/rear.html

Thanks Rick I found that duri g a search but am still looking for the gear ratio for a 4l60e.

MBZTECH

· #4 · Jul 6, 2012

Ask and you shall receive. RICK

Gear ratios on these units were 3.06 1st gear, 1.63 2nd gear, 1.00 3rd gear, .070 4th gear.and you shall receive. RICK

Nova_Guy

· #5 · Jul 6, 2012

Each tenth is worth 100 RPM at any speed. So you would gain 200 RPM at any speed in any gear by going from 3.70 to 3.50.

S.Humrich

Discussion Starter · #6 · Jul 6, 2012

MBZTECH said:
Ask and you shall receive. RICK

Gear ratios on these units were 3.06 1st gear, 1.63 2nd gear, 1.00 3rd gear, .070 4th gear.and you shall receive. RICK

Lol yeah I found it and it seems right on. It looks like I should be on the bottom half of the 3's to keep the rpm's down. 3.70 at 2800 rpm is 83 mph which is close to my 80 mph. Now if I switch to 3.50 gears I would be at 2800 rpm's while at 90 mph. Man I really hate this. Thanks for the help

S.Humrich

Discussion Starter · #7 · Jul 6, 2012

Nova_Guy said:
Each tenth is worth 100 RPM at any speed. So you would gain 200 RPM at any speed in any gear by going from 3.70 to 3.50.

So let me see if I understand. 2800 rpm at 80 mph with 3.70 rears. Changing to 3.50 rears would put me at 2600 rpm at 80 mph. Is this right and what would you say is about right for a street car. I do like to drive fast, spin my wheels but don't think the high rpm's are good on a long trip.

Thanks steve

MBZTECH

· #8 · Jul 6, 2012

No problemo. If you lived down in S

c. California. You would be in peoples way at 83 mph!

S.Humrich

Discussion Starter · #9 · Jul 6, 2012

MBZTECH said:
No problemo. If you lived down in Sc. California. You would be in peoples way at 83 mph!

I live in nor cal and it isn't much different that's why I'm looking to get the rpm's down at the higher speed

Steve

MBZTECH

· #10 · Jul 6, 2012

2,600 rpm is still to high for long trips. 2,200 rpm would be much better. maybe just 1 inch taller tire would help. Try the taller tire on that chart.

sevenzeronova

· #11 · Jul 6, 2012

shumrich said:
So let me see if I understand. 2800 rpm at 80 mph with 3.70 rears. Changing to 3.50 rears would put me at 2600 rpm at 80 mph. Is this right and what would you say is about right for a street car. I do like to drive fast, spin my wheels but don't think the high rpm's are good on a long trip.

Thanks steve

I wouldn't go much less than the 3.50

S.Humrich

Discussion Starter · #12 · Jul 6, 2012

MBZTECH said:
2,600 rpm is still to high for long trips. 2,200 rpm would be much better. maybe just 1 inch taller tire would help. Try the taller tire on that chart.

Cool thanks

LeftCoast Carl

· #13 · Jul 6, 2012

currently running 3.08:1 posi on 195/15 tires. It's quite respectable for cruising and still has some jump. If your motor can overcome the tall gears,you'd have a winner for sure,in my opinion.
Leftcoast Carl

MBZTECH

· #14 · Jul 6, 2012

sevenzeronova said:
I wouldn't go much less than the 3.50

We got MARIO SPAGETTI ripping up and down hwy 1 at subsonic speeds here! LOL

Nova_Guy

· #15 · Jul 6, 2012

shumrich said:
So let me see if I understand. 2800 rpm at 80 mph with 3.70 rears. Changing to 3.50 rears would put me at 2600 rpm at 80 mph. Is this right and what would you say is about right for a street car. I do like to drive fast, spin my wheels but don't think the high rpm's are good on a long trip.

Thanks steve

That should be correct.

S.Humrich

Discussion Starter · #16 · Jul 6, 2012

sevenzeronova said:
I wouldn't go much less than the 3.50

Ok why not do you think I won't be happy. I'm running a ls3 with 4l60e and ford nine inch with 3.70 gears. I have thought of a mini tub because all I can fit now is a 8" rim. Right now all I have to do is mash the pedal at almost any speed and the tires spin and at lower speeds I have to be careful pulling away from lights. The rpm's are high at highway speeds and I want the engine to last. The funny thing is my truck has a 5.3, 4l60e and 373 gears with 22's and I love it. Is it really that different with 17's to 22's.

S.Humrich

Discussion Starter · #17 · Jul 6, 2012

LeftCoast Carl said:
currently running 3.08:1 posi on 195/15 tires. It's quite respectable for cruising and still has some jump. If your motor can overcome the tall gears,you'd have a winner for sure,in my opinion.
Leftcoast Carl

Great now I really don't know what to do. My truck came stock with 308's and I switched them to the 373's and loved it thats why I went with the same set up in the nova but I didn't think the 22's would be that much do a difference over the 17's. Boy oh boy I guess I was wrong

MBZTECH

· #18 · Jul 6, 2012

Would the car still look good with a little taller tire. I have the same engine trans combo in my suburban 1,800 at 75 mph. And it still loves gasoline. The taller tire will really slow the rpms down.

MBZTECH

· #19 · Jul 6, 2012

shumrich said:
Great now I really don't know what to do. My truck came stock with 308's and I switched them to the 373's and loved it thats why I went with the same set up in the nova but I didn't think the 22's would be that much do a difference over the 17's. Boy oh boy I guess I was wrong

Carl how tall are you're tires?

S.Humrich

Discussion Starter · #20 · Jul 6, 2012

MBZTECH said:
Would the car still look good with a little taller tire. I have the same engine trans combo in my suburban 1,800 at 75 mph. And it still loves gasoline.

Right now I have 245-40-17 in the rear which is 24 inches. I have maybe a half inch clearance on both inside and outside. So now that we know I can't go wider what would you suggest for taller.

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