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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: 84scottsdale454 on May 28, 2011, 10:47:43 am

Title: top speed of 79mph? wth? rear end gears?
Post by: 84scottsdale454 on May 28, 2011, 10:47:43 am
i have a stock 454 installed with a turbo350 trans, i cant look at my gears at this time......can someone give me an idea on what they will be? i think this rear end was custom built before i bought it! any ideas?????????
Title: Re: top speed of 79mph? wth? rear end gears?
Post by: Psycho71 on May 28, 2011, 11:20:52 am
what kind of rpm are you turning at 79mph, or 60mph, or whatever? Tire size will ploy a role in that as well. With both of those figures, and the 1:1 thrid gear of the th350, it's just math to get the rear end ratio.
Title: Re: top speed of 79mph? wth? rear end gears?
Post by: 84scottsdale454 on May 28, 2011, 11:29:33 am
unsure of the rpm, it was the max rpm because thats all it could take....i could not go 80mph! the tires size are the stock height
Title: Re: top speed of 79mph? wth? rear end gears?
Post by: VileZambonie on May 28, 2011, 02:38:20 pm
You have given nowhere near enough information for anyone to even venture a guess and at that all you will be getting are random guesses.
Title: Re: top speed of 79mph? wth? rear end gears?
Post by: malibu795 on May 28, 2011, 10:30:53 pm
You have given nowhere near enough information for anyone to even venture a guess and at that all you will be getting are random guesses.
yep
Title: Re: top speed of 79mph? wth? rear end gears?
Post by: slammed79 on May 28, 2011, 10:34:50 pm
Shove a $30 dollar tach in there and get a rpm reading. Then please report back with rpms and the actual tire size. Stock doesn't help in the slightest.
Title: Re: top speed of 79mph? wth? rear end gears?
Post by: 84scottsdale454 on May 28, 2011, 10:50:57 pm
your a smart man slammed79..... imma get a tach, me and the ol man pulled it out today, they were 4.56s! well thats what he says anyway! i appreciate your help! i dont know much when it comes to things like this! i wish i could get a pic on here, my truck is 1 of a kind! thanks again
Title: Re: top speed of 79mph? wth? rear end gears?
Post by: beastie_3 on May 28, 2011, 11:31:26 pm
count the teeth of the pinion and ring, then divide one into the other to get the gear ratio, but it should be stamped on the ring.
Title: Re: top speed of 79mph? wth? rear end gears?
Post by: malibu795 on May 29, 2011, 02:07:38 pm
Why count it stamped in the ring gear tooth count
Title: Re: top speed of 79mph? wth? rear end gears?
Post by: beastie_3 on May 29, 2011, 03:11:41 pm
thats why I said it should be stamped....
Title: Re: top speed of 79mph? wth? rear end gears?
Post by: VileZambonie on May 29, 2011, 09:55:48 pm
driven over drive = :1

Title: Re: top speed of 79mph? wth? rear end gears?
Post by: 1979C20 on May 31, 2011, 05:27:25 am
Your speedometer could be wrong if the rear end gears are different than stock. What type of phone do you have? If you have an android phone, download a gps speedometer and check your speed with that.
Title: Re: top speed of 79mph? wth? rear end gears?
Post by: 84scottsdale454 on July 24, 2011, 08:37:44 am
I used 2 diff speedometers on my droid phone! I'm sure any idiot could determine they were low,thanks for the reply "79"! Now I'm runnin 3.08s and they seem perfect! I can't still smoke the 22s at 20mph kickdown
Title: Re: top speed of 79mph? wth? rear end gears?
Post by: chevymanrob on July 24, 2011, 12:43:48 pm
4.56s even with a 26" tire and 79 mph should be about 3800 rpm. if your engine wont turn past that you may have some MAJOR issues. i think the "buy a tach" advice was the best thing said to this point.
Title: Re: top speed of 79mph? wth? rear end gears?
Post by: 84scottsdale454 on July 24, 2011, 10:42:29 pm
i dont feel the need to buy on tachs look TACH-Y, i know how to blow a motor up and to keep from doing it. i solved the problem with 3.08s and my motor runs flawless and is practically new so maybe my phone is a turd or something! either way THIS MAN IS HAPPY LOL