10 bolt carrier spacer for running lower gears

[monster man]

hey all, this pertains to a car I'm building, but I figured the 10 bolt truck/car setups were the same. To run 4.10's in a 8.5" 10 bolt that originally has 2.40 gears, all I'll need is the $30 spacer from Summit made by Mr. Gasket and a new ring and pinion correct? Will the spacer only allow me to run 3 series gears in a 2 series carrier, or will it let me run 3 series OR 4 series? Maybe I'm stuck with 3.90's in other words? Is it that simple or will I need any other parts I'm not aware of? Thanks!

 

[pauly383]

As far as trucks go with 10 bolts , that I have surmised , 2.73 and lower ( high number ) is the same carrier . There are tons out there . No one wants their rear 10 bolts round here . Could get one cheapo .

I am just about to put 4.56's on my 3.08 10 bolt front

 

[monster man]

2.73 and numerically up is the same, you're right. That's where I screwed up- I pulled a 10 bolt with 2.40 gears Actually, it's out of a Pontiac Grand Prix, but I assume they're the same internally

But, since it's already bolted into my model T roadster I need to make do with what I have. I'd like to go with spacer route since it's cheaper and cleaner than a whole new carrier from the junkyard, and I can't find any in the junkyard with 4.10 or 3.90 gears anyway

 

[pauly383]

I don't think 3.90 was a GM used ratio , 4.10's weren't used much in 1/2 tons , and 3/4 ton fronts are valuble since d60's are hard to get cheap .

With that much weight ( Model T ) , I would think you didn't need much more than 3.08's . I have those I'd be happy to give you , with carrier

 

[monster man]

thanks for the offer, I'll keep it in mind! Those numbers are based on my calc's- I need to be able to light the tires up from a standstill without a line lock, and also limit my top speed to 100MPH or so- it gets to be a real white knuckle ride going that fast! With the 2.40's now, it's fast, but it hiccups off the starting line, and cruises at 25MPH in third at about 800 RPM, so I have to keep it in first or second til then