Rear End
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Joined: Aug 2008
Posts: 98
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From: North Muskegon MI.
Rear End
I've got a 1973 350 w/ headers,intake and a 4:11. I'd like to go on the x-way some time with out running 3 grand at 55 mph. I don't drive her very hard most of the time and would like to change the diff to either a 3:33 or 3:55 not sure what way to go. What ya guy's think would be better? Would a 3:33 make it a little dogie?
Burning Brakes
Joined: Dec 2008
Posts: 971
Likes: 45
From: Middlesex NJ
Check out the speed analyzer at Keislers site.
http://www.keislerauto.com/speedanalyzer.html
Not sure how strong your motor is but with a small block I would not go bellow a 3.55. Just to keep the kick in the pants around town.
I know some guys will will disagree but unless you've got a pretty torquey small block you will miss the 4.11's around town. I am sure you like how the 4.11's dig in around town.
I had a 70 nova with a mild built 350 and turbo 350 trans and the 3.73 were great around town but the highway was a little screamish at 65. Was always in the slow lane.
You could always keep the 4.11's and spend a little more $$ and go 5 spd.
then you can go 70 at 3krpm
http://www.keislerauto.com/speedanalyzer.html
Not sure how strong your motor is but with a small block I would not go bellow a 3.55. Just to keep the kick in the pants around town.
I know some guys will will disagree but unless you've got a pretty torquey small block you will miss the 4.11's around town. I am sure you like how the 4.11's dig in around town.
I had a 70 nova with a mild built 350 and turbo 350 trans and the 3.73 were great around town but the highway was a little screamish at 65. Was always in the slow lane.
You could always keep the 4.11's and spend a little more $$ and go 5 spd.
then you can go 70 at 3krpm
Burning Brakes
Joined: Jun 2003
Posts: 1,022
Likes: 6
From: CT
Ive run 4 diff ratios in same 4spd stick car with a 350/375hp car.
3.55s stock swapped out during rebuild, 3.73s blew up, 3.36s temp rear diff, 4.11s, and now have new 3.73 12 bolt.
I hated the 3.36 gears they didnt match my rpm range of my cam and heads, car felt really doggy driving around town. The 4.11s were fun I could drop clutch and burnout 1st and 2nd gear, but highway sucks so i couldnt drive to any shows. I have to say I like 3.73 gear the best for both tire spinning fun and cruising at 70mph. I have a 28" tall tire
I would recommend 3.55s for your car if you have 27" tires. 3grand would probably be 70mph instead of your current 55mph. my 3.73s and 28" tires do 70mph at 3,300-3,400rpm, still revs but my 4.11s were 3800rpm at same speed.
3.55s stock swapped out during rebuild, 3.73s blew up, 3.36s temp rear diff, 4.11s, and now have new 3.73 12 bolt.
I hated the 3.36 gears they didnt match my rpm range of my cam and heads, car felt really doggy driving around town. The 4.11s were fun I could drop clutch and burnout 1st and 2nd gear, but highway sucks so i couldnt drive to any shows. I have to say I like 3.73 gear the best for both tire spinning fun and cruising at 70mph. I have a 28" tall tire
I would recommend 3.55s for your car if you have 27" tires. 3grand would probably be 70mph instead of your current 55mph. my 3.73s and 28" tires do 70mph at 3,300-3,400rpm, still revs but my 4.11s were 3800rpm at same speed.
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Try a taller tire.
I run 28" tire on my '74 and i believe i can run a couple more inches - 30" maybe. From your signature pic it looks like u have some room for a taller tire. Remember that when u change tire height u change the calibration of your speedo.
Like the taller the tire the faster u go at same rpm but speedo reads lower. If u have too u may run a narrower tire to fit up inside the wheel well to get a better rpm on the freeway at 65mph.
Did u change the trans speedo gear when you installed the 4:11? Or did u but the car like that. U may want to get the speedo/trans gear calibrated first (for your current tire size) so u will know where your really at on the freeway (@ actual 65mph). Most drive train shops will do the calc for you and have the trans/speedo gears in stock.
Hope this helps,
cardo0
Like the taller the tire the faster u go at same rpm but speedo reads lower. If u have too u may run a narrower tire to fit up inside the wheel well to get a better rpm on the freeway at 65mph.Did u change the trans speedo gear when you installed the 4:11? Or did u but the car like that. U may want to get the speedo/trans gear calibrated first (for your current tire size) so u will know where your really at on the freeway (@ actual 65mph). Most drive train shops will do the calc for you and have the trans/speedo gears in stock.
Hope this helps,
cardo0
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