6spd to 8spd

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JosephVK56

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lol well i havent gotten parts... and if i do it it wont be for a while.. this is more of a thread to give other people contemplating it an idea of what is involved as i have seen MANY interested in this as well
 

Wild one

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lol well i havent gotten parts... and if i do it it wont be for a while.. this is more of a thread to give other people contemplating it an idea of what is involved as i have seen MANY interested in this as well

You might want to look up a guy by the name of Larry Rose,and pick his brain,he's making an 8HP90 sort of work in a 70 Challenger,and has found a few ways around the computor end of the tranny.Another outfit you might want to try and engage would be Diablo,as I think you'll need a little expertise on the tweaking and tuning end of the 8 speed. Good luck,i wish you well.I took the easy way out and traded my 6 speed truck off on an 8 speed truck,lol.
 

Wahrsuul

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And after all that........you still have that crummy 3.55 rear end, which is the crux of your whole delema.

And why do the 3.55's get such a bad rap? And it's "dilemma".
 

crackerjack1957

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And why do the 3.55's get such a bad rap? And it's "dilemma".
Tall gear on the 5/6 speeds effects launch & towing capabilities with 3:55
8-speed helps a lot on launch.
3:55 okay for normal driving with smaller diameter tires.
If you run 35 inch or larger tires this gear is constantly downshifting below 70 mph.
 
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JosephVK56

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Ya 3.55 sucks on 5/6 speeds cause the insanely long trans gearing. 8 speeds are so short that the diff gearing doesnt matter much. 3.55 with 8 speed is a pretty good combo
 

Wahrsuul

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OK, 3.55 = bad with larger tires, got it. I'm still on the stock 20" wheels and will probably remain so. That being said, I wouldn't mind locating a 3.92 posi in a junkyard somewhere I could swap out for my 3.55.
 

mondo

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You might want to look up a guy by the name of Larry Rose,and pick his brain,he's making an 8HP90 sort of work in a 70 Challenger,and has found a few ways around the computor end of the tranny.Another outfit you might want to try and engage would be Diablo,as I think you'll need a little expertise on the tweaking and tuning end of the 8 speed. Good luck,i wish you well.I took the easy way out and traded my 6 speed truck off on an 8 speed truck,lol.
Id just like to add, get a hold of AJ (Hemituner Performance) and Jim ( True Street Performance ) and pick their brains also.
 

Jeepwalker

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Good luck. Seems like an utter waste of time to me, but I've plenty of time wasting projects of my own.
 

RLJ10X

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Wahr, I love that yellow truck. I've always liked yellow, tho. But you do have to keep yellow clean to look good. My Chrystal Granite Wrangler looks pretty good even if it's dirty.

3.55s stink out loud because the 5/6 has a really tall first gear. It's like having to start out in second. By the time you get moving, the other guys, with proper gears have shot off the line, and are gaining momentum. That not just racing, that's every time you go to get groceries, or whatever.

4.10s are the gift that keep on giving. There is no advantage like Mechanical Advantage.

With 3.55s, my truck wouldn't even shift into "6th" gear until 60 mph. Therefore, at 55mph, with 4.10s my truck's engine is turning the exact same rpm as it did with 3.55s. Once you go over 65, you will probably lose an mpg or 2. But keep it at 65 or less and there really is no downside to 4.10s, except for the installation cost.

Add a Hemi Fever Tune and you transform your truck from a sad moaning, lugging slug (slug may be a bit harsh, but right now, I can't think of another word that better describes my truck with 3.55s) to a lighter, quicker, happier machine.
 
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