How to pick rear gear???

[t76turbo]

There is no telling with this truck. I didn't even think about that. Is it really from a 69?

The PO did all kinds of swapping and upgrading that I am still trying to figure out 4+ years later.

[crazy longhorn]

The nose says 69-70....I know that 71-72 did not have the bowtie on the hood. My 69 has a 71 hood (no bowtie). The fun part is,how many last players? My 69 has a 2000 5.3/ 6 spd richmond, connected with a 55 chev bell. All the brakes, are from a 75 c-10....yes, disc up front/drum rear. The rear diff from the same truck, 12 bolt 3.40 gear. The drive shaft , came out of a 77 3/4 ton 2wd, & other than one conversion u joint, stock as a rock. Its a labor of "love"....sit down, strap in,shut up, & hang the big F on! Longhorn

[James the III]

Originally Posted by clinebarger

3.73 is what I would do, When you break the 700R4 & go with a 4L80E.....The 3.73 will work better than a 3.42 with the 80's 2.48 low gear

I know this is a loaded question as it's somewhat of an opinionated question/answer..
But does a street worked over 454 with most likely north of 550hp and loads of torque, really need 3:73's even with the 4l80e 2.48 first gear..

Sure the 3:73 or 4:10s will make it more fun IF you can get traction in the no weight over the axle truck..
But for a mostly street use toy.. that won't have an adjustable 4 link rear to hook the power.. and only going up in smoke that much faster.. looks cool but not fast..
and a 3.42 gears truck will have no problem turning over the tires into smoke..

I'd think if he said it was more of a street/strip usage.. then sure.. but a mostly street.. all you do is make it even easier to blow the tires off it..

[crazy longhorn]

Originally Posted by James the III

I know this is a loaded question as it's somewhat of an opinionated question/answer..
But does a street worked over 454 with most likely north of 550hp and loads of torque, really need 3:73's even with the 4l80e 2.48 first gear..

Sure the 3:73 or 4:10s will make it more fun IF you can get traction in the no weight over the axle truck..
But for a mostly street use toy.. that won't have an adjustable 4 link rear to hook the power.. and only going up in smoke that much faster.. looks cool but not fast..
and a 3.42 gears truck will have no problem turning over the tires into smoke..

I'd think if he said it was more of a street/strip usage.. then sure.. but a mostly street.. all you do is make it even easier to blow the tires off it..

I am not Cline, but what I have seen, is that the lower you go on the gears, the slower the axle speed (less spin) on take off. With 4.10 gears, my Longhorn would go straight the 1st 3 gears....hang onto your azz around 100 mph, in 4 th or 5th! Off the soap box, let Cline in...longhorn

[b454rat]

With the cam and convertor used, you have to be in the engines operating range. With a numerically lower gear, you will be below it. Think of a turbo diesel engine turning too low RPMs not spooling the turbo, or a 2 stroke not in it's power band. When going "rowdier" with an engine the more the parts have to match. Parts meaning the entire vehicle, not just motor...

[James the III]

Originally Posted by b454rat

With the cam and convertor used, you have to be in the engines operating range. With a numerically lower gear, you will be below it. Think of a turbo diesel engine turning too low RPMs not spooling the turbo, or a 2 stroke not in it's power band. When going "rowdier" with an engine the more the parts have to match. Parts meaning the entire vehicle, not just motor...

I understand that.. but it is a BIG BLOCK 454
even before you get "on the cam" rpm range it will still have gobs of torque ..
And there is something to be said for getting rolling before you get in the meat of the power in a limited traction vehicle..
Again.. I'm thinking mainly street.. if it was street strip.. ya, gear it to leave on the cam..
On the street if gearing it to be "on the cam" only blows the tires off.. it's kinda pointless..

[clinebarger]

Originally Posted by James the III

I know this is a loaded question as it's somewhat of an opinionated question/answer..
But does a street worked over 454 with most likely north of 550hp and loads of torque, really need 3:73's even with the 4l80e 2.48 first gear..

Sure the 3:73 or 4:10s will make it more fun IF you can get traction in the no weight over the axle truck..
But for a mostly street use toy.. that won't have an adjustable 4 link rear to hook the power.. and only going up in smoke that much faster.. looks cool but not fast..
and a 3.42 gears truck will have no problem turning over the tires into smoke..

I'd think if he said it was more of a street/strip usage.. then sure.. but a mostly street.. all you do is make it even easier to blow the tires off it..

This is a very opinionated subject

You also have to consider what RPM your going to run at cruising speed.....
3.73 gears, .070 OD, & 29" tires will put you right around 2,000 at 70 MPH, I wouldn't want lower than that.

[crazy longhorn]

Originally Posted by clinebarger

This is a very opinionated subject

You also have to consider what RPM your going to run at cruising speed.....
3.73 gears, .070 OD, & 29" tires will put you right around 2,000 at 70 MPH, I wouldn't want lower than that.

Just to be clear on the mess...Cline was it the rpms you were talking, or the lower numerical gears? I am still thinking about that 4l80-e trans senerio? Put that motor into the sweet spot on cruise? Making guesses, what would it be ...maybe 22-2400? My thoughts are , that would not be a bad cruise range for a hot rod? Bring it back Cline....I will listen, & learn Longhorn

[James the III]

Originally Posted by clinebarger

This is a very opinionated subject

You also have to consider what RPM your going to run at cruising speed.....
3.73 gears, .070 OD, & 29" tires will put you right around 2,000 at 70 MPH, I wouldn't want lower than that.

and a 3.42 you get better around town mileage and not much loss in fun factor with a big block.. and might just not need that o/d

I had 3.23 ish gears in my el camino and could blow the tires off at will with a tired 402

[clinebarger]

Originally Posted by crazy longhorn

Just to be clear on the mess...Cline was it the rpms you were talking, or the lower numerical gears? I am still thinking about that 4l80-e trans senerio? Put that motor into the sweet spot on cruise? Making guesses, what would it be ...maybe 22-2400? My thoughts are , that would not be a bad cruise range for a hot rod? Bring it back Cline....I will listen, & learn Longhorn

The RPM, I personally don't like to be under 2,000 at 70 MPH.....

My Camaro has 3.42 gears with 25.7" tires with a .070 O/D which is almost identical to a 3.73/29"/.070 combo.......My L92 is not short in the torque department at all putting down 444 ft.lbs. at 2,950.

My cam is big enough that it will buck a little if I get to far "under the cam" with the converter locked.........which would be way worse if I was running a Higher (numerically lower) gear.

If one of my customers is going to run any kind of decent power on the street, I always recommend Drag Radials as opposed to trying to gear it to not spin which doesn't always work.

Not that there aren't times when you have to gear a vehicle a certain way to get it hooking from a dig even with Drag Radials.......But this is usually boosted cars......I had a '50 Studebaker pick-up LS1/4L60E with a TVS1900 supercharger, Started with 3.90 gears & ended up with 3.00 gears before it would hook then I had to deal with the part throttle driveability issues that came with it, (It had a 9" Ford, If your questioning the odd gear ratios)
This truck is VERY light compared to a Chevy full size pick-up.

A 4L80E's .75 O/D will put him at 2269 at 70 with 3.73's which is perfect in my opinion.

[t76turbo]

That's all a lot of info.

I am a little hesitant to pick gears based on a trans I may go to. I do not drive this truck hard and will not be racing it so with the upgrades I did the 700r4 may live. But in the back of my mind I am looking for a good 4l80e just to have available if the time came. But it is definitely good to think about. Thanks for all the good input.

I went ahead and pulled the entire rear end out. Well, almost. Just need to get some caps for the brake lines and then unbolt the u-bolts and it's out. . I want to really clean it well (pressure wash and degrease) before I bring it to my friends shop. That way once I get it back I will degrease one more time, wire wheel it, then prep and paint it.

[crazy longhorn]

Originally Posted by t76turbo

That's all a lot of info.

I am a little hesitant to pick gears based on a trans I may go to. I do not drive this truck hard and will not be racing it so with the upgrades I did the 700r4 may live. But in the back of my mind I am looking for a good 4l80e just to have available if the time came. But it is definitely good to think about. Thanks for all the good input.

I went ahead and pulled the entire rear end out. Well, almost. Just need to get some caps for the brake lines and then unbolt the u-bolts and it's out. . I want to really clean it well (pressure wash and degrease) before I bring it to my friends shop. That way once I get it back I will degrease one more time, wire wheel it, then prep and paint it.

Listen to what Cline had to say, He is well respected hear Longhorn