rear weight

[TR32]

Pretty much common knowledge that the trade off for the strength of a 9" is the extra horsepower it takes to turn it. If your worried about breaking the rearend the most you need behind a 4 cyl is an 8 in, at least it's lighter and still has the gear ratios.
If I had the choice I would go for the 8.8 or the small ford if you could find one. What makes the 8" & 9" use more hp is the positioning of pinion in relationship to the ring gear. You can talk to to hot rodders or off road guys.....

[car62]

if you do go with the 9"...i have 4 empty "N" cases ill sell you

[7uptruckracer]

All of yall are totally missing the point talking about HP trade off. Running 4th gear 1:1 with the correct final drive takes less HP then running the others in 3 or especially 2nd like he is. Your losing the HP in the transmission through all the gears. Not to mention its not the greatest on the trans. Its not much heavier then the other rear ends and your not running it through all the reduction. He already had a 9" under the truck and no one seemed to know they make the 7:40 gear. We have to shorten the 9" housing anyways and put all the bracketry on it for the leaf springs so you can get all your angles right. I run the track and run up front there every week you can't reinvent the wheel no one else runs 2nd gear 3rd at the least...

[mark41]

what he said!! with the 1 to 1 you can start of in 3rd gear and shift to fourth with a 7.40 in the rear. Definetly don t try to reinvent the wheel....just my .02...

[racerman]

I've ran 1 to 1 and through the transmission. Tried all different combos in my 15 years racing. I would rather use the lightest rear end available. Seems to run better with the lighter stuff. What works for one might not work for another.

[7uptruckracer]

This is a 4/10 Mile racetrack with lots of straightaway for a 4 cylinder you definitely can't afford to lose the torque thats why people build the 9" rears we don't have a reliability issue with axles, maybe C clips if your dumb enough to run those. You can get away with 3rd gear but It does hinder you here we are already over weight and Nose heavy so adding a few pounds isn't hurting but killing your whole straightaway is way bigger. We are on 15" tires and rims they don't accelerate or pull hard compared to others. YOu can get the gained weight back down by changing your building design I'm 2550 with a heavier motor but I built it light I know Supertruck isn't that light with the same chassis so you can gain back what you lose. With some handling he has a good foundation.

[drtlvr]

On a 4cyl racecar with less then 200 horsepower, lighter is ALWAYS better. Too many wins and champions use 7.5 rears to argue that point.

[7uptruckracer]

Yeah I have quite a few championships and wins myself BUT this isn't a mini-stock its a Mini Truck on 15" wheels and rims your trying to wind up. That isn't nearly as light its not Pound per CC. I know what I'm talking about I run 4cyl Trucks, a Mod 4 with the only DOHC Toyota Motor with a 500 Holley on it in the world that runs a stock intake from Australia, as well as Dirt Late models. Ive seen the Dyno numbers myself and can provide sheets if you'd like your looking at 20% losses running it in third on our motors with an Inertia Dyno. I'd be willing to put anything out of my shop that runs in fourth gear against your 3rd gear I can always lighten stuff elsewhere to compensate. You have to remember this is a truck not a car. Different trans and driveline rules. They wind up slower then hell and handle nothing like a car you can't spin these wheels if you try and he already has a 9" your talking 30 lbs maybe and the 7:40 gear is lightened in itself. No disrespect but you can't go outside what wins hear by running stuff that doesn't even make sense I said maybe 3rd would work if you didn't have provisions for anything else but 2nd gear which is the case here this isn't dirt with a pinto trans you have to turn 9k, your asking alot of your driveline to wind up those big tires every lap

[7uptruckracer]

The top 5 at langley all run 9" in 4th I ran a 7.27 final and turned 7500/7600, He ran 2nd with a 7.40 and runs 7300 same motor he honestly has more then I do it just won't tote it in those gears, and I'm going to kill someone on a restart everytime that running 2nd if i change the restart pace hes screwed.

[drtlvr]

Yeah I have quite a few championships and wins myself BUT this isn't a mini-stock its a Mini Truck on 15" wheels and rims your trying to wind up. That isn't nearly as light its not Pound per CC. I know what I'm talking about I run 4cyl Trucks, a Mod 4 with the only DOHC Toyota Motor with a 500 Holley on it in the world that runs a stock intake from Australia, as well as Dirt Late models. Ive seen the Dyno numbers myself and can provide sheets if you'd like your looking at 20% losses running it in third on our motors with an Inertia Dyno. I'd be willing to put anything out of my shop that runs in fourth gear against your 3rd gear I can always lighten stuff elsewhere to compensate. You have to remember this is a truck not a car. Different trans and driveline rules. They wind up slower then hell and handle nothing like a car you can't spin these wheels if you try and he already has a 9" your talking 30 lbs maybe and the 7:40 gear is lightened in itself. No disrespect but you can't go outside what wins hear by running stuff that doesn't even make sense I said maybe 3rd would work if you didn't have provisions for anything else but 2nd gear which is the case here this isn't dirt with a pinto trans you have to turn 9k, your asking alot of your driveline to wind up those big tires every lap

OK. Didn't mean to ruffle feathers.

[7uptruckracer]

Its all good, Id agree on a lot if it was a normal application but these seem to be off the beaten path. Not much works thats conventional. If it was a ford mustang id totally agree on the rear end, but this is a very annoying animal. Leaf springs and bad geometry on top of a lead sled and lack of tech really makes it tough

[drtlvr]

Yea, no teching is always a problem.