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Old 03-12-2018, 08:03 AM   #26
1project2many
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Re: Rear end ratio for 700R4?

I'm sure we'll see a bunch of "no problem" responses, and that's fine. There are folks here who have good luck putting a V6 T5 behind an engine producing 350 ft/lbs or more as well. Hell, I used a 7.5" GM rear behind a 455 Buick in a Monte for 9 years without blowing it up. But that doesn't make any of these parts the best choice and it doesn't mean the parts are inherently good. The fact that there are survivor stories often says more about the user and the application than the part.

What's most frustrating to see in this thread is the number of responses suggesting a less expensive but practical solution involving a 2.73 rear and 350 trans should be dumped for a more expensive solution: buy new gears or rear axle then spend quite a bit more to rebuild and upgrade a transmission to go with the new rear. Why spend more to achieve what is easily done with less?

The Monte I mentioned had 2.26:1 rear gears and produced around 400 ft/lbs at 1600 rpm where it liked to cruise. Even though it only had three speeds (thm 400) it could take off plenty quick and still achieved 16-18 mpg on long cruises. I still have the car 29 years after I built it and I hope to get time rebuild it some day. I suppose I'd be told that I should ditch the rear for a 3.42 then spend money building and upgrading a 2004R if I asked for suggestions on the rebuild.

Last edited by 1project2many; 03-12-2018 at 08:10 AM.
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Old 03-12-2018, 08:42 AM   #27
DransportGarage
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Re: Rear end ratio for 700R4?

Quote:
Originally Posted by 1project2many View Post
<snip>

What's most frustrating to see in this thread is the number of responses suggesting a less expensive but practical solution involving a 2.73 rear and 350 trans should be dumped for a more expensive solution: buy new gears or rear axle then spend quite a bit more to rebuild and upgrade a transmission to go with the new rear. Why spend more to achieve what is easily done with less?

<snip>

I suppose I'd be told that I should ditch the rear for a 3.42 then spend money building and upgrading a 2004R if I asked for suggestions on the rebuild.
Oops. I didn't realize that was what I was doing. I thought a member posted a question and I was helping him out -- sharing my experience. I thought that's what we did here, along with trying to find best (not necessarily cheapest) solutions for our trucks. At the end of the day I was actually going to allow the OP to continue to own his truck and make his own decision. Signing off of this thread...
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'55 3100 (383/700R4)--'55 Belair Sedan (350/4-speed)--'64 'Vette Conv. (327/4-speed)--'68 GTO Conv. (462/4-speed)--'69 Cutlass Conv. (350/TH350)--'06 'Vette Conv. (LS2/6-speed)
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Old 03-12-2018, 11:54 AM   #28
1project2many
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Re: Rear end ratio for 700R4?

Dransport, you are very helpful and provide earnest advice as do so many here. This is a good community and signal to noise ratio is consistently good.

But please look carefully. Technically when the OP mentioned the THM350 he (or she?) did not ask a question. He posted a plan:

Quote:
"Way ahead of you DransportGarage - I did a roll test today. Yep, it's an actual 2.73. So I'll be selling my 700R4 and replace it with a Turbo 350 - cheaper and simpler too. "
Although not a common approach these days, I believe this solution has merit. OP posted benefits from following this plan and I believe they are valid. In fact I've tried the same approach. There are no gross flaws to making it work and no obvious reasons to say "bad idea." There are low ratio gearsets available for the 350 which can help improve acceleration off the line if it's a concern, although no concern has been raised yet. So I see no reason to push toward the 700 / numerically higher rear axle ratio if the OP is not so inclined.

I realize that you were just sharing an opinion. It was presented well and invited consideration. And ultimately either approach can net satisfactory results. But what followed your opinion was frustrating to watch. The wagon train started rolling without anyone directly addressing the usefulness of the OP's plan. I'm not sure why the thread turned into a defense of the 700R4 or of the choice to use one with a numerically lower gear ratio. But the internet is a fickle place and these things happen.

Last edited by 1project2many; 03-12-2018 at 12:46 PM.
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Old 03-17-2018, 02:35 PM   #29
evilokc
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Re: Rear end ratio for 700R4?

stock gearing on my 1991 firebird is 2.73 with a 700r4. runs about 1700rpm at 70mph on the highway. smooth as silk. not a hotrod but it feels great in the highway.
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