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  #16 (permalink)  
Old 03-04-2010, 07:46 PM
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damn, power went out today ( uncle needed lines down to do tree work over my house ) got back online and was really impressed with all the responses! this is gonna take a whole lot more thought than i had originally figured. you know, i never even considered my truck being actually heavier than a car, i just figured that bed was so light, all i really got for weight is the cab and engine. guess i was dead wrong there. i have considered putting hella bricks in the bed, because as this thing is shifting, its just smoking tires at the same time. ( hella wore out tires, fact is i just smoked one of them clean off, it popped and ripped apart ) and thats with like, not a whole lot of pedal. anyway, im opening up the rear end this weekend and checking things out. im leaning towards the 3.08 gearing, its gotta be better than whats in there now. but of course its just a thought till i really see what i got and do more math. thank you guys for the responses, its got me going in the right direction, mike

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Old 03-04-2010, 08:04 PM
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Quote:
Originally Posted by diamond mike
its got me going in the right direction, mike
Trucks are notorious for being heavy in all the wrong places- high CG and front heavy. Just part of the nature of the beast- and that's why you can load >/= 1000 lbs. in the back and still drive from "A" to "B".

A healthy BBC will spin tires, regardless of what it's in, within reason- also the nature of it. But I honestly think you can handle it, although you saying you spun a tire off doesn't bode well for things like parts breakage, frequent tire replacement and traffic tickets.

Time will tell! lol

But I think you'll like the 3.08's just fine if you do a lot of highway driving. But there are other ratios (some not nearly as common OEM) that you might find in a 'yard.

Oh, and nix the bricks! If you do anything, make it solidly mounted to the truck- not loose. God forbid what would happen in a rollover, etc. w/a ton o' bricks flying around...

There are bumpers (not the ideal place to add weight, but...) made of large diameter tubing w/welded ends that can be filled w/water.
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Old 03-04-2010, 08:46 PM
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actually my buddy suggested mounting a fuel tank behind the wheels, like a 20-25 galloner, would help with the weight some....ive thought of getting a sheet of quarter inch thick steel for its bed
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Old 03-04-2010, 11:07 PM
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A 4' x 8' x 1/4" steel sheet weighs about 325 lbs.

25 gallons of gasoline weighs about 155 lbs. plus weight of the tank, etc. and cost roughly $70 to fill.

A 1' ID x 5' long tubular bumper would hold about 245 lbs. of water. Add the weight of the bumper and mounts to this.
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Old 03-04-2010, 11:19 PM
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Quote:
Originally Posted by cobalt327
A 4' x 8' x 1/4" steel sheet weighs about 325 lbs.

25 gallons of gasoline weighs about 155 lbs. plus weight of the tank, etc. and cost roughly $70 to fill.

A 1' ID x 5' long tubular bumper would hold about 245 lbs. of water. Add the weight of the bumper and mounts to this.
Fill that bumper with lead shot instead of water if you really want weight.

I'd fix the rear suspension so it will hook better before I just dumped a ton of weight onto the truck, weight slows you down.
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Old 03-04-2010, 11:46 PM
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Full of lead (solid, not shot)- ~2775 lbs. Mercury filled would be 3325 lbs, give or take.

At the circle track at Orlando Speed World, a car broke its frame- and dumped quite a few hundred pounds of mercury onto the track!

Said he bought the chassis that way and had no idea of the Hg being inside the frame rails...

Anyway, if I were the OP, I'd just concede the 60' time. He doesn't race anyway, so really, nothing needs added, IMHO.

Putting the obligatory tool box in the back (maybe saddle boxes on each side), a spare tire in the OEM location (could fill that w/sand or water lol ) and maybe move the battery into the box would be all I would ever consider doing, if that.

I just don't think standing start performance is what he's looking for.

But burning the tire off the rim... I still think that's a bad indication of what's in store.

Last edited by cobalt327; 03-04-2010 at 11:59 PM.
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Old 03-05-2010, 07:55 AM
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diamond,
there should be a tag on the diff you can decode to know what gears it is supposed to be...
then:
there are a bunch of "how to" count wheel rotation(s) versus drive shaft rotations on the web to determine ratio without counting teeth depending on which type differencial...
to confirm the tag or figure it out with no tag...

random gooogle poor pick example:
http://www.jeepforum.com/forum/f9/fa...-ratio-615380/

from what info you are posting,,,I would use a higher EP rated/synthetic gear lube than the OEM spec so may be wiser to pull the cover and count teeth???

guys,,,
the "bricks" comment to create a motor load condition was a joke but your right,,,some yo-yo might actually do it so I'll delete it,,,should have prefaced it with LOL....

LOL,,,how about one of those huge high density poly tanks the yard spray guys use bolted to bed to add motor load...
"could be" filled with a party beverage!!!
have a accident/filled with water and fire retardant = mega fire extinguisher!!!

quicker weight transfer is what your after for better traction and that comes from changing/improving the front suspension first...
often just a couple of softer durometer sway bar links donuts and looser/free center bushings helps...
and/or different shocks..
let's the front suspension lift quicker and farther to transfer weight to the rear quicker is the goal...
(DON'T use "all" soft donuts,,,your truck center of gravity is too high/prone to roll over in a accident)

adding weight is a bad last resort because it is going to impact mpg,,,especially stop and go in town...
CRS = is it 100lbs = 1mpg at hwy cruise???

Last edited by red65mustang; 03-05-2010 at 08:24 AM.
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  #23 (permalink)  
Old 03-05-2010, 10:00 AM
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I run a 3.08 gear with my 1/2 ton bbc powered 70 chevy with 28 inch tires. It is a nice balance between city and highway driving. On city streets, I would prefer a 3.42 gear and on the highway I would like a 2.73, so the 3.08 is right in the middle. So the 3.08 leaves me wanting a little different gear all the time, but the only solution/compromise for a 3 speed trans.

a 1/2 ton (c10) 75 chevy with a short bed should weigh around 3800 pounds.

You should also considering bolting a OD on the end of the 400 trans. You can find them used on e-bay/craig's list. gear vendor.

Pulling a used 3.08 from a junk yard 1973 to 1978 c10 truck is also a good idea. Cheap fix.

it cost me almost 1000.00 in parts to put in new 3.08 gears and a limited slip center section in my truck. I highly recommend a limited slip diff for your truck. Traction will be much much better with a LSD.
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Old 03-05-2010, 10:12 AM
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I have a 500+hp 427 big block in my 58 and it has 4.56 gears with a 700R4 that had the old style valve body that they put in a check ball and the converter locked up when it went into 4th gear so I didn't have to have anything but a tv cable.I run 31x10.5 tires and still got 12 miles to the gallon at 70 miles per hour.Before I switched to the 4.56 gears I ran 3.73 gears and found myself cruising at 90 everywhere I went.I wasted the 4 year old 700R4 on the drag strip when I went into tire shake in third gear.I bought a 4L80E to replace it.Over drive is your best option in my opinion
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Old 03-05-2010, 11:01 AM
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With the low rear gear ratio/OD combo, the only real downside is a high driveshaft RPM on the freeway. But as long as the geometry is correct, the d-shaft's balanced and the diff's up to it- good bearings, set-up and lube, it should do OK.

In the OP's case, I'd still probably just go w/a 3.08 from the 'yard and keep the TH400. At least to begin with. Somewhere down the road- maybe different tranny AND gears.
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  #26 (permalink)  
Old 03-05-2010, 11:09 AM
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I couldn't tell you how many of my customers have complained about a vibration after changing from a 2.xx gear to a 3.73 or 4.10. It's all due to the drive shaft speed. A stock drive shaft is fine in most cases at high speeds with 2.xx or 3.07 gears, but when changing to a 3.73 or 4.10 the drive shaft can distort at high speed. The drive shaft diameter must be increased or a more ridged material must be used to keep the drive shaft straight at higher speeds.

I built transmissions for a Busch Grand National team years ago. I built a Jerrico 4 speed into an overdrive transmission to use at a road race. When they started practicing they noticed a vibration that they couldn't find. Another team asked about the drive shaft diameter. They were running a 3 inch drive shaft. The other team loaned them a 3 1/2 inch drive shaft and the vibration went away.
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