i wish to upgrade to 373 ring and pinion and maybe install Eaton limited slip unit in my GM 7.5 10 bolt.
the cars got a 700r4 stock tranny , and i was wondering if that would affect the highway rpms at all?

>>i would like to gain slightly quicker launch off the line when i need it but retain a low rev while in Overdrive on the highway.

 

if you are expecting to get 3.73 and you are planning to travel at around 70 to 80 mph, expect to be above 2500 rpms easily, for an example, if i am going 90 mph on my gauge, im actually only going 66mph @ 2500 rpms
my gauge is off by 1.36 percent, its not actually a mph off
heres another example: i used to be able to go 80 mph at 2000 rpms with my 2.73s, now i can only go like 60 mph and be at like 2200

 

You should have no problems going down the highway at around 2000-2200 RPM's at about 65 or 70. The 700r4 is my favorite trans, i used it with a 456 gear in the rear and could still go up on the highway at about 60 mph with around 2500-2700 RPM's!

 

cuz it tachs around 2800-3500 at 85 now... i think the speedo and the tachometer are off anyway.. but aside from that >>>its safe for me to get 373 gears with my 700r4 tranny and not be taching out during highway speeds? im gettin conflicting answers between ppl on the forums and friends i know.

 

With a 3.42 gearset and a 700R4 with a 27" tall tire, you should be at ~2100 RPM... With a 3.73 gearset and the rest the same, you'd be at ~2300 RPM... So, not much of a problem... Would probably help your V6 out too...

 

i dont think we are trying to give u conflicting answers, we are just stating from person experience. im just saying be ready for higher rpms especially if you use to have 2.73 or something like that, especially if you have loud exhaust to some it really gets annoying going down the highway and just hearing the car whine, doesnt bother me

 

yall worry too much

he will be fine with 700r4 and 3.73 this was factory combination in billions of gm vehicles and other vehicles,

time to worry about more important things

happy swapping and cruising

:P

 

I wish my truck's rpms were that low on the highway.

My truck has a 4L80E, 4.10 gears and 28" tall tires. I just came off the highway from a short road trip. At 60 mph, my engine is at 2500 rpm. I'm normally cruising closer to 75 mph and the rpms are just over 3000. The 454 sucks a lot of fuel at those rpms.

 

we arent worrying, we are just stating what he is getting into, i debt if someone didnt have this board to go to to find out things first, they probably would of wished they wouldnt of went with that ratio. im not saying there is anything wrong with this combination.