Gears -- 4.56 or 4.88?

[mabrodis]

- Your impression of the truck’s ability to climb up steep grades at speed -- necessary to downshift (out of overdrive) to continue at speed?
>driving in Denver, my vehicle (fully loaded with gear at 7000 lbs) sucks ass.

Not the vehicle...just you Ali...

Congrats on the btw...

 

[Cruiserdrew]

I've had the 4.88s for 2 years and would not want the 4.56s. Even with 4.88s these trucks are not quick, and with a full load are positively sluggish. Those big tires take a while to spin up, and the lower effective gearing makes it a bit easier on your transmission. If I lived and stayed in the flats, 4.56 would be acceptable, but with the Sierras out my back door, 4.88s are the only way to fly. My 80 feels like a rocket compared to my 60 as well! Everything in life is a series of trade-offs and the 4.88s work better for me, given my needs and circumstances. If you want speed, get a 100 series. If you want to run 35's on an 80, get 4.88s. See you in Moab.

 

[Hondo]

I went with the 4.88s, but am still waiting for the fronts to come in (they were on national backorder).

That reminds me, I need to call Cruiseroutfitters...

 

[alia176]

Not the vehicle...just you Ali...

Congrats on the btw...

Thanks Mark. The baby is doing great and we get no sleep

Ali

 

[alvarorb]

Hondo,

Good choice!
I also have 4.88 on La Cabra, and agree with Cruiserdrew. Plus, I like to be able to move up hills when the truck is loaded. So what if the top speed has dropped a bit. You probably won't want to drive a lifted 3 ton beast at more than 80 mph.
Sor speed accuracy, I rely on my GPS.

Regards

Alvaro

 

[SR.GRINGO]

I have 4.88's on a 94 80--love them. My cruising speed on the freeway is about 70. I live at sea level but most of the wheeling trips take us into the Mountains--perfect set up. The brand is http://www.precisiongear.com/ The tires are 315 BFG M/T´s. If I did it again or end up with anonther cruiser some day I would do it exactly the same.

 

[reffug]

I am running stock gears at the moment with 33" tires with absolutely no problems. I run any passes or ranges without consideration of OD at the present. However in the future I am planning on going to a true 35" or 36" tire and at that point will swap out to 4:56 gears. For my needs I think the 88's are overkill and since my truck will already climb the tallest passes in the US w/o taking OD off or turning on power mode I am certain the 56's will be more than sufficient for my uses.

 

[landtank]

I am running stock gears at the moment with 33" tires with absolutely no problems. I run any passes or ranges without consideration of OD at the present. However in the future I am planning on going to a true 35" or 36" tire and at that point will swap out to 4:56 gears. For my needs I think the 88's are overkill and since my truck will already climb the tallest passes in the US w/o taking OD off or turning on power mode I am certain the 56's will be more than sufficient for my uses.

While you probably won't regret not going to 4.88s, as it's hard to miss what you never had, running 4.56s is just a waste. I've been running 4.88s for 5 years at speeds of 80+ mph and haven't had any issues at all and get as good gas mileage as the next guy. There is no downside to running them.

 

[Nay]

I am running stock gears at the moment with 33" tires with absolutely no problems. I run any passes or ranges without consideration of OD at the present. However in the future I am planning on going to a true 35" or 36" tire and at that point will swap out to 4:56 gears. For my needs I think the 88's are overkill and since my truck will already climb the tallest passes in the US w/o taking OD off or turning on power mode I am certain the 56's will be more than sufficient for my uses.

Not sure where you are driving to make claims like that. I have 33's and stock gears and live at 7,400 elevation. It is an absolute dog in OD running up the long hills at even this elevation (stockers don't do at that well, either). Running up I-70 with OD on from Denver (5,500 ft) to Eisenhower tunnel (11,800 feet) and maintaining speed limits? Or Vail pass coming east from Vail? Not a chance.

Most late model cars have a hard time doing that, much less a built 80. I have to lock out OD on my 240 hp minivan to keep it rolling up there, and even then when a truck cuts me off to pass I'm down in 2nd @ 4,500 RPM trying to get back the speed.

Here is the question: what are you achieving in increased highway speed RPM with 4.56 or 4.88 that you don't get by simply locking out OD? You have a 3 gear automatic transmission with OD gear reduction for fuel economy. Let it ride in OD down the big hills at nice low RPM's, and lock it out and use 3rd gear on the up hills...75 mph in 3rd with 315's should be about 2,700 - 2,800 RPM, which is perfect. And clicking that little button is free. If you don't like the way it runs with OD off and your RPM's higher...your problem is engine power.

Where you really need the gearing is offroad. 4.10 with 35's is too high for rock crawling at high elevations. For that purpose, I agree that 4.56 is a waste of money.

Nay

 

[Darwood]

I am running stock gears at the moment with 33" tires with absolutely no problems. I run any passes or ranges without consideration of OD at the present. However in the future I am planning on going to a true 35" or 36" tire and at that point will swap out to 4:56 gears. For my needs I think the 88's are overkill and since my truck will already climb the tallest passes in the US w/o taking OD off or turning on power mode I am certain the 56's will be more than sufficient for my uses.

Reffug, do you have forced induction? If not I don't believe you. I don't think a stock truck let alone one with 33's can avoid downshifting into 3rd while going up steep hills. I recently was traveling the I40 from Flagstaff to Albuquerque and then up the I25 to Colorado Springs, and my truck was in 3rd almost as much as it was in overdrive for the trip. You might not be putting the truck out of overdrive, but either the torque converter is unlocking or it's downshifting into 3rd (or even 2nd) for you. Either that or you don't mind going 35mph.

 

[cruiserdan]

Not sure where you are driving to make claims like that. I have 33's and stock gears and live at 7,400 elevation. It is an absolute dog.....<SNIP>>

He is turbocharged, that's why he claims that.

I am also on 33's with stock gears and mine pulls hard (blower).

 

[MoJ]

Good thread for the FAQ, it just leaves me with 1 question.....

What should I expect to pay (ballpark of course) in labor to have someone re-gear for me?

 

[reffug]

Not sure where you are driving to make claims like that. I have 33's and stock gears and live at 7,400 elevation. It is an absolute dog in OD running up the long hills at even this elevation (stockers don't do at that well, either).

My rig has been all over the US.

As previously stated by Dan my rig is Turbo'ed with a rather advanced BLITZ control system out of Japan.

Sorry for failing to state that I forget what I consider the obvious sometimes.:whoops:

It will pull extremelly hard.

 

[apcoleman]

Good thread for the FAQ, it just leaves me with 1 question.....

What should I expect to pay (ballpark of course) in labor to have someone re-gear for me?

It is all going to depend on whether or not you pull the third members or have someone else do it. By pulling the thirds yourself you can save a substantial amount of money. Biff pulled his own and had someone gear so you might want to do a search for that or send him a PM

 

[Nay]

My rig has been all over the US.

As previously stated by Dan my rig is Turbo'ed with a rather advanced BLITZ control system out of Japan.

Sorry for failing to state that I forget what I consider the obvious sometimes.:whoops:

It will pull extremelly hard.

Well, that beats the hell out of gearing .

I was heading out to the store, so thought I'd pull some real world figures. 1995 with 108K miles on 2.5 OME with new 33x12.5x16 TRXUS. Stock gears with speedo correction.

RPM figures with overdrive on:

60 mph - 2,000 rpm
65 mph - 2,150 rpm
70 mph - 2,300 rpm
75 mph - 2,475 rpm
80 mph - 2,650 rpm

RPM figures with overdrive locked out (3rd gear)

60 mph - 2,650 rpm
65 mph - 2,850 rpm
70 mph - 3,050 rpm
75 mph - 3,250 rpm

On a long uphill grade of about 3%, it wil bog down at about 65 mph with overdrive engaged. It needs to be running at 2,600 rpm to keep speed, and 2,800 is where you start to hit the sweet spot. I don't think that 4.56 would even come close to achieving this.

So if you plan to regear @ 7,000+ elevation, you would want the overdrive RPM to be about 2,400 @ 60 mph so that 75 mph was right around 3,000 RPM. I think that 315's would run on stock gears with OD locked out right at 3,000 RPM, which is pretty much ideal. You just have to get used to some manual shifting.

One of the key things for those non-supercharged types who live at high elevation to keep in mind is that the ability to manually control a 4 speed auto tranny becomes important on a tall lift with big tires...and is probably more important than regearing (4.56 may well create a bad middle ground for you where 3rd is too low and OD is too high).

I don't think I would regear for road use...but you'd need it for high elevation wheeling for sure. I'd like to see real world figures on 4.88...I'm not sure that 5.29 should be written off until you can see the RPMs.

Nay

 

[Jason Andrews]

gears...go for the 4.88's!

Yo Hondo! I would second the notion that the 4.56 are a complete waste of time and money. I have had PG 4.88's for a couple of years and the 35 bfg's and my speedometer runs about as true as it gets to stock. A better question is 4.88's or 5.29's. I live up in the elevation also. Taking it from 5,200ft. on I-70 to 11,800ft at the Eisenhower tunnel is quite a haul for the first steep parts. I take my s*** up to 95mph pretty regularly when I hit a downhill and keep the momentum goin!! I would not worry about having the rpms to high!...its a YOTA! I also have regularly driven it at 87-92mph all the way from Denver to Kansas City,...an 8 hr drive and the rpms are always in a safe spot. ~2850? My weak ass 3FE needs them to stay up above 2800 to maintain its speed. Good luck bud.

 

[cruiserdan]

It is important to remember that the higher (numerical) you go the gears get weaker. It's a lot easier to break 5.29 gears than 4.10 gears. I still takes effort to do so but not quite as much. Ironicly we install weaker gears in order to work the vehicle harder....

 

[Tools R Us]

It is important to remember that the higher (numerical) you go the gears get weaker. It's a lot easier to break 5.29 gears than 4.10 gears. I still takes effort to do so but not quite as much. Ironicly we install weaker gears in order to work the vehicle harder....

Some are going the other way on that debate.

http://www.gearinstalls.com/410suck.htm

 

[landtank]

Why do these guys with forced induction jump in these gearing threads with their opinions. BUGGER OFF!

 

[alkaline747trio]

Hey skyshark, what kind of top speed do you comfortably get with 33's and 4.88s?