Axles

[trmaggie98]

Currently running a 84 Jimmy with a 305, auto trans, 208 transfer, and 3.08 gears and 33' tires.

I need more gear. I think 3.73's will be fine. I'm not building a crawler or mud truck. Just a dependable driver that I can take off road.

What is the cheapest way to get 3.73's? Replacing gears or axles swap from junk yard?

Are there any 3/4 or 1 ton axles that may have 3.73's and disk brakes?

 

[shady]

Is it an OD tranny? or 3 speed?
if it's an OD with 33"s you'll probably like 4.11 better. I have the tbi 350/700r4/33"s and Im going 4.11 as soon as I can.

3 speed i'd do the 3.73's though

 

[trmaggie98]

Was told it's a 700r4, but not sure. Don't know how to tell.

 

[shady]

and the newer body 2000-> can have 3.73 or 4.11 with disc's. just gotta search around.

try here
http://www.car-part.com/

 

[trmaggie98]

Are those direct swaps?

 

[shady]

no but not hard. if you want direct swap I think the 1 ton rears need perches moved if I remember correctly..? Not sure.

 

[sweetk30]

tranny pan square with 1 corner 45* cut off = th350 = 3 speed

tranny pan slight rectangle all 4 corners intact = 700r4 = 4 speed overdrive.

as said if 3 speed 3.73 be good all around .

if overdrive min 4.10-4.56 . this keeps the engine in rpm power range when in overdrive and keeps it from going up/down 4th/3rd 3rd/4th . and killing the tranny .

 

[trmaggie98]

Thanks. I'll look when I crawl under it tomorrow night

 

[trmaggie98]

It's either a 700r4, 4l60 or 4l60e

 

[trmaggie98]

I just never feel the OD cause of the high gears.

 

[sweetk30]

4l60-e nope that's full computer controlled newer version .

4l60 is middle version for only 2-3 years if I recall.

so should be just 700r4 .

 

[trmaggie98]

Thanks.

 

[Deuling]

Go to a 4.10 gear ratio with 33s.


I went 4.56s with mine on 33s and its pretty damn awesome.


I actually kinda wish I had gone 4.88.


The deep gears actually made the engine not work as hard, so it didnt kick up rpms the way I thought it would, as I dont need to keep in the pedal as hard on inclines etc...

 

[trmaggie98]

So 4:10's with the 33's? Then I would need 456 if I went to 35's.

 

[Deuling]

So 4:10's with the 33's? Then I would need 456 if I went to 35's.

If i did 35s, i would not go any lower numerically than 4.88s. Thats just my opinion. But i jsut did a gear swap with 33s, and the 30 or so miles i put on after showed me that it worked damn good.


I like the 4.56s with 33s and a 700r4. For the first time ever, overdrive actually feels like it kicks in and locks in. Rather than kicking out from a slight breeze against me....

 

[trmaggie98]

Thanks. I'm scouring the internet now for new axles and pricing getting new gears put in my 10 bolt.

 

[rjfguitar]

I would do at least 4.56's. Remember, the most widely used ratio in K20 and K30 trucks was 4.10 with a stock 31" tire. That ratio, even without an overdrive is just right for a balance of power and economy. The 3.42's and higher found in the K10's are incredibly stupid, that would be why they quit using those ratios later on in the 1990's. Those 2.73, 3.08, 3.42 ratios had to do with an idea around emissions output and trying to reduce them IIRC. That is part of the reason why the 700R4 was developed with a pretty low geared 1st gear.

So... anyway, stepping up to a 33", 4.56 would be about right. I would go 4.88 if it was me, do it once and be done. You then could step up to 35's and still be geared pretty well.

 

[Deuling]

I would do at least 4.56's. Remember, the most widely used ratio in K20 and K30 trucks was 4.10 with a stock 31" tire. That ratio, even without an overdrive is just right for a balance of power and economy. The The 3.42's and higher found in the K10's are incredibly stupid, that would be why they quit using those ratios later on in the 1990's.

So... anyway, stepping up to a 33", 4.56 would be about right. I would go 4.88 if it was me, do it once and be done. You then could step up to 35's and still be geared pretty well.

Yep. Like i said. I kinda wish i would have done 4.88s....


It may be a bit on the high side, but still i think it would be reasonable, unless it was a vehicle i drove highway only all the time... At that point i think 4.10 would be perfect to keep the 700r4 happy in OD on the highway and still get decent MPG.

I will say I was never really happy with 3.73s and 33s. It just lugged, even with a torqy 400 small block.