Regear vs overdrive transmission

[Ramba_ral]

Hi everybody i have a quandary. I have a 79 k5 blazer with a 350/th350/np205 and 35 in tires with 4.11 gears.
It spins about 2700 on the high way and wanting to get that down a little bit.
I figure i can go down to 3.73 gears or get a od trans(like a 700r4 or a 4l80e).

Note im not concerned about gas mielage just wear and tear on the motor. Thank you for the advice.

 

[ZooMad75]

Actually going to the OD with the 4.11's would be a good combo with 35's. That combo at 65mph would be 1790 rpm. Your other idea of keeping the TH350 and going down to 3.73 gears would only bring the cruise rpm down to 2300 rpm.

One downside to going down in gear ratio is it's going to kill the acceleration from a standing start. Just makes it feel doggish. By keeping the gears you have you save money on regearing the axles and get the bigger rpm drop of the 700's OD gear. Plus the 1st gear is much better than the TH350 too.

 

[HankScorpio]

I have run 36" and 37" for years with 4.10 and no OD. If you ever want to jump up a size you will hate a 3.73. 37's are the new 35. I agree with ZooMad75, low gear with OD drives better.

 

[onetonbb74]

Try to keep your motor at 2k on the freeway in OD. I love 37s and 5.38s with OD. I ran 3.73s th350 and 36s, hated it.

 

[tenderfoot]

My old '79 had that set up only with a 203. I loved it. When I went to 4.11s I loved how it slowed me down in the snow. No brakes + all wheel drive = unfowlable traction.

 

[HankScorpio]

My old '79 had that set up only with a 203. I loved it. When I went to 4.11s I loved how it slowed me down in the snow. No brakes + all wheel drive = unfowlable traction.

I had that setup for a while in a longbed 3/4. It was good, had a B&M ratchet shifter so it was pretty fun on dirt to slap shift and rip around.

 

[Ramba_ral]

Thanks for the info all! Now i just need to save up to get that od transmission

 

[Hogback Fabrication]

High highway RPM's wear engines out faster?

 

[YOUNGBLOOD13]

OD all the way. You'll get a lower first gear and od. It's win win.

 

[TuckerK5]

I have 4,56 on 33s with od. 2000 RPMs at 60 is perfect to me. Great low end acceleration and no lugging at 60. Very little throttle. Great gas mileage.
If I were driving it 70 everyday it would be too much gear.