Gears on 5.3 swap
 

Just wondering what some of you guys are running for gears behind your 5.3 swaps and what your tire size is.

Re: Gears on 5.3 swap
 

I went with the 3.42 ratio. This was the gear ratio in the '08 GMC donor truck. Still working on putting the truck together.

Re: Gears on 5.3 swap
 

Just going by the 02, she runs way getter with the 3.73's (29" tire). Longhorn

Re: Gears on 5.3 swap
 

I have the 4l60e and I used to run 3.08's and it bogged a lot on highway. now i run 3.73's and it has a lot more bottom and highway driving is much nicer too.

Re: Gears on 5.3 swap
 

I have a 3.42 with a 4L60e and a 29" tall tire. I had this tire & rearend in my last vehicle with a 700r4 and I didn't hate it, but I do wish I'd a gone with a 3:73.
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Re: Gears on 5.3 swap
 

Well that makes me a little happier. I found a posi unit (4 series) with 3.73's in one of my extra rear ends and was thinking they may be to high for the 5.3 but i guess i'll be rebuilding that one now. Thanks everyone.

Re: Gears on 5.3 swap
 

Truck doesn't have the 5.3 yet.

I'm going to swap in the 5.3/5-speed tranny first, then drive it with the current 4:10 ratio long enough to determine what the best ratio would be.

This should avoid any "I shoulda/coulda" type regrets, or multiple experimental swaps to find what works best.

Re: Gears on 5.3 swap
 

Try a gear ratio calculator... plug in the blanks and it will tell you RPM at MPH ...

http://www.summitracing.com/expertad...tio-calculator

Re: Gears on 5.3 swap
 

I have a 6.0 with 3.42 gears. I am sure that 3.73's would bring her performance up, but honestly she has plenty of pep already and even with the 4l80e tranny I am still getting close to 19 mpg. I am more than happy with both.

Re: Gears on 5.3 swap
 

My 71 2wd Blazer with 5.3 and 4l60, 3:73 is pretty tough.....I think that it would spin the tires all the way through 2nd gear. The acceleration with the 3:73 is really fun. I am running truck rallys with 275/60 R15 BFG

Re: Gears on 5.3 swap
 

lq4 6.0l/4l80e, posi 3:42 gears 28" tire.... 1900 rpm @ 60 mph.

Re: Gears on 5.3 swap
 

4.10s + 4L60E with 315/35/20s = Fun. It will be a little more fun once I get a higher stall converter too. I'm sure its costing a few MPG, but I have 1500 miles on it in 3 years....so I'm not too concerned (still get 16+)