Would I feel a difference

[Skunksmash]

Would I feel a difference going from 2.73 to 3.23's in the rear end? The final gear on the 700R4 (which I have in my truck) is .70 so that would put me at 1950 RPM at 75 mph. That's about right for me and my tastes.

So would it really be worth it to do it? Am I going to be able to feel the difference in acceleration? Or would I be better off just leaving the 2.73's?

[INSIDIOUS '86]

Great gear to swap to. I felt a difference going from 2:73s to 3:08 and a bigger difference 3:08 to 3:73s. This should help gas mileage all around

1950 cruise rpm is a little on the low side for me unless you have a torqey motor but hey my old 305 did fine at 1500rpm on the hwy gutless till you dropped second...lol
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[THE "10" SILVERADO]

Originally Posted by INSIDIOUS '86

Great gear to swap to. I felt a difference going from 2:73s to 3:08 and a bigger difference 3:08 to 3:73s. This should help gas mileage all around

1950 cruise rpm is a little on the low side for me unless you have a torqey motor but hey my old 305 did fine at 1500rpm on the hwy gutless till you dropped second...lol
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Not to distract from the OPs question, but did you like the 3:08s? My truck has them and I was thinking maybe with the new motor and tranny I should upgrade to something better.

[LEEVON]

You'll feel it, but it's a small jump. Why not go on up to 3.42's? You'll be in the sweet spot with 28-29" tires but it's still a conservative gear.

Get this, my last '87 came from the factory as a 305 with TH375 (TH400 w/ TH350 tailshaft) and 2.41 rear gears. Honestly it was great to drive, I really enjoyed the highway cruising. I swapped a 700R4 and 3:73 posi rear and actually regretted it.

[68Timber]

I would go at least 3.42's.

[LONGHAIR]

Originally Posted by LEEVON

Get this, my last '87 came from the factory as a 305 with TH375 (TH400 w/ TH350 tailshaft) and 2.41 rear gears. Honestly it was great to drive, I really enjoyed the highway cruising. I swapped a 700R4 and 3:73 posi rear and actually regretted it.

2.41 with 1-1= 2.41
3.73 with .7-1=2.61

I would think that the lower first gear would be better and the final drive isn't that much lower? You really regretted the swap? Because of the cost w/o much change?

[INSIDIOUS '86]

Originally Posted by THE "10" SILVERADO

Not to distract from the OPs question, but did you like the 3:08s? My truck has them and I was thinking maybe with the new motor and tranny I should upgrade to something better.

I have a th350 so it was nice to have them for the highway but they really were not well suited for my engine with its power in the upper rpm band. 400hp still couldn't top out the gear.
I have the 3:73s and love them but hwy mileage is garbage till I get an overdrive trans.
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[INSIDIOUS '86]

Originally Posted by LONGHAIR

2.41 with 1-1= 2.41
3.73 with .7-1=2.61

I would think that the lower first gear would be better and the final drive isn't that much lower? You really regretted the swap? Because of the cost w/o much change?

What tire size is that based off of just for the sake of a more accurate idea of what gearing would be.
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[LEEVON]

Originally Posted by LONGHAIR

2.41 with 1-1= 2.41
3.73 with .7-1=2.61

I would think that the lower first gear would be better and the final drive isn't that much lower? You really regretted the swap? Because of the cost w/o much change?

Mainly because of the time and expense it took to swap, when the original combo was pretty tolerable. The first 700 burned up (used) so I bought a nicer unit then much time and money into it for a driver. Then I sold truck...so not worth the effort.

Otherwise the last 8, 10? or so trucks I've had were 700R4 (or 4L60e) with 3:23, 3:42 or 3:73 on 28-29" tires.

[Skunksmash]

Well how bout this. I want to do 85 mph, at 1,900 RPM. On 29 inch tall tires, with a .70 final gear in my 700R4 transmission. That should dictate what rear end gears I should get.

[LEEVON]

You need 2.73 gears to attain 1882 RPM at 85 mph with .70 final drive ratio on 29" tires.

[INSIDIOUS '86]

That may actually kill mpg. Working the engine to hard to get to speed and maintain it causes more throttle input and will use more gas as a result. I wouldn't go lower than 308s numerically since after all we are driving bricks
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[lilpoindexter]

3.73's in my straight six T5 truck. 3.42's would probably be a little better mpg wise than 3.73's, but who cares? The 3.73's make it better. 3.23's would defintely be nicer than the 2.73s

[Skunksmash]

Originally Posted by LEEVON

You need 2.73 gears to attain 1882 RPM at 85 mph with .70 final drive ratio on 29" tires.

Dang it. Gear vendors, here I come. Eventually. When I have more money. LOL

Yall ever heard of them? Somehow, you stick this thing on the back of your transmission, and you magically gain another gear. It must be real magic! Cause that's the only way I can explain it...