Read end options - asking again

[oldmansmonte]

So I've apparently got my Caprice sold tomorrow(we all know how that goes) so I'm getting ready to choose a rear end for the Monte.

My friend advises again the Ford 9" because of possible clearance issues. Not sure how true that is but I'll likely go with a GM 12 bolt.

1) Who would you guys get it from

2) I want aggressive gears but I'm not going 4.11's. To high. I've got 2:73's now. I do some Highway traveling. Usually half hour trips at most but I would like to leave open the option of a 1-2 hour trip if need be. I'm thinking 3:73's but part of me thinks 3:55's would be a better compromise.

Thoughts.

 

[Opie Knievel]

Which transmission are you running?

 

[oldmansmonte]

Which transmission are you running?

200R4

Of god I just looked up my code, I have 2.41 gears. This thing has to go.

 

[383_GrandPrix]

When I finally get mine all together I'll be running 3.73 or 4.10 gears with a 700r4, 2500 stall converter and 28" tall tires. I plan on taking it for 2H trips. With this set up I calculated the car will run at 2200-2500 rpm at 120km/h (75 mph)

 

[383_GrandPrix]

http://www.differentials.com/technical-help/differential-gear-ratio-calculator

 

[Opie Knievel]

200R4

Of god I just looked up my code, I have 2.41 gears. This thing has to go.

I know what you mean. I've got "airplane gears" in my Monte Carlo too. With the overdrive, I'd probably go with 3.73's.

 

[oldmansmonte]

http://www.differentials.com/technical-help/differential-gear-ratio-calculator

Thanks. It calculates me at 70 mph at 2,000 rpm. Oddly I feel like this car runs high on the thruway. I think its something to do with my TBI setup. I've checked it and the car definitely gets into 4th, and I lock up the torque converter, but I just feel the car doesn't want to maintain speed much above 55. And I have no cruise control. If it's like that now with 2.41's I can't imagine what it'll do with 3.73's. I'll have to lift the car when I get home and do a chalk test and make sure the old timer I got the car from(He's probably deceased now, he would be 99) didn't swap the gears. Although I HIGHLY doubt it.

 

[Texas82GP]

No tach in the car? 3.42 or 3.73 should be a good compromise with the overdrive. What is your tire size and what is the first gear ratio in the 200-4R?

 

[oldmansmonte]

No tach in the car? 3.42 or 3.73 should be a good compromise with the overdrive. What is your tire size and what is the first gear ratio in the 200-4R?

Ok going off of memory, rear tires are 235/70/15 I believe. Calc said 29.75 total height. First gear is 2.74.


Edit: I added a tach but either the filter isn't working or it's not grounding correctly because it bounces all around so I'm not much in the habit of staring at it.

 

[Texas82GP]

I think you meant 27.95, which is what I came up with. Tall tire. 2.74x3.42=9.37 final drive in 1st gear. 2.74x3.73=10.22 final drive ratio which is still acceptable. 1st shouldn't feel like granny gear. With that tall of a tire, I would go with the 3.73. 2.74x4.10=11.23 which is getting a bit steep.

With a 3.73 and, a 27.95" tire and a 0.67 overdrive ratio I calculate 2403 RPM at 80mph (129km/hr). Yeah, I would go with the 3.73. If you plan on putting a shorter tire on there, like a 60 series, then go with the 3.42.