gears for 35's, are 4.56's too low?? - Page 2 - Diesel Forum

dondiesel444 · 03-02-2005, 09:07 PM

so 4.30's sound good. where did you get them?

I'll probably just put the $ towards more power and go with gears when (IF) I ever get 38's-40's. unless I can get a smoken deal somewhere on 4.30's

redrocket · 03-02-2005, 11:43 PM

Randys ring and pinion is where I bought mine.

redrocket

Loser1 · 03-03-2005, 12:17 AM

I had a local shop do the install. From what I understand, the 4:30 sets are starting to be hard to come by for the 10.5 rear end. My local shop got their hands on 3 sets and 1 of those sets went into my truck. It could be all BS though?!?

L1

mikeym · 03-03-2005, 12:59 AM

doubt theyll be a shortage as ford installs them as factory equipment on a lot of their trucks. even if you cant find new ones, junk yards should have them avaliable and you can always look for lifted gassers, so if they have theyre stock gears still...

ZooDad · 03-03-2005, 01:10 AM

I got my 4.30 from a Ex member here that switched them out. You might check with some of them. IF you ever plan to go bigger than 35, go for the 4.30's.

ZooDad

jetski86 · 03-03-2005, 02:11 AM

A couple of things to remember. The diesel only has a limited rpm range. A gasser cruises at 3000 these are almost maxed out there.
Also I have found the best fuel economy is 2100 or under. Drop the rpms down as much as you can without lugging it.

sno_cat · 03-03-2005, 06:38 AM

[ QUOTE ]
most likely I'll go with a bigger lift and tire in the FAR FAR future, and if I did swap for 4.10's I'd kick myslef later on.

[/ QUOTE ]

That is what I said and it didn't last long [img]/ubbthreads/images/graemlins/eek.gif[/img]

superf350 · 03-03-2005, 09:29 AM

[ QUOTE ]
I don't know what to do, I definatly want to get 35's real soon, but I don't wanna swap 4.10's in there, it's not THAT much of a difference to justify the cost. however who knows in the future if I'll go with an even larger tire, 37"-38" is probably the biggest I'd ever want for my needs.

I guess I'll jsut stick with the 3.73's and 35's for now and add some more power mods to make up the difference [img]/ubbthreads/images/graemlins/smokin.gif[/img] unless I can find anyone with 4.30's who'd wanna swap axles.

most likely I'll go with a bigger lift and tire in the FAR FAR future, and if I did swap for 4.10's I'd kick myslef later on.

[/ QUOTE ]

I've got 4.10's and 38's and the truck does pretty good, especially cruisin down the highway. The 6.0's got 35's and 3.73's and it'll roast em in first and second on level 3! [img]/ubbthreads/images/graemlins/eek.gif[/img] [img]/ubbthreads/images/graemlins/smokin.gif[/img]

double · 03-03-2005, 09:44 AM

as many others have said, i think that you could actually get by with 35s and 3.73s. now, if you tow regularly, then i would consider gears. can you add some HP and torque to compensate if you do not add gears? yes, but what was done to address the shifting points and eliminate some stress on the tranny?

i have 4.56s in my truck and i am running 37s. this truck USED to be a daily commuter (50k in one year), and the 3.73s were fine running up and down the freeway at 75mph. now that she is used to primarliy pull my toyhauler, i moved up in gears. i can no longer run 75 without hitting 2500 rpms, but i feel better that the tranny likes me a whole lot better when it's got 12k in tow...

so, try running with 3.73s for a while... it might work fine for what you are looking to do...

dondiesel444 · 03-03-2005, 10:12 AM

I have a 6-speed so I don't have to worry about stressing the tranny any. I don't tow with this truck, thats what I have a Mack for! so for just cruising around I guess 35's and 3.73's will be fine. I am happy with the 3.73's and 295's now I am just affraid I'll lose lots of power when I switch to 35's...

ducky · 03-03-2005, 11:33 AM

If you don't use the lowest forward gear of the 6 speed to get rolling you might play with that in the gear calculators since that will be about like stepping up the gears in the rear ends.

I am wanting a slide in camper and it is so heavy it looks like a 450 is going to be needed. Problem is the stock gears suck on the road when unloaded so I may wind up with some tires for when unloaded and then run the factory rims and tires when loading the slide in camper if I want to do things that way.

One consideration I am looking into is how well the low gear of the 6 speed will help get the load moving even with non stock tires.

But I am still learning and not close to ordering so maybe I am wrong on this concept.

tsaelens · 03-03-2005, 11:50 AM

[ QUOTE ]
I have a 6-speed so I don't have to worry about stressing the tranny any. I don't tow with this truck, thats what I have a Mack for! so for just cruising around I guess 35's and 3.73's will be fine. I am happy with the 3.73's and 295's now I am just affraid I'll lose lots of power when I switch to 35's...

[/ QUOTE ]

I used to have 35's and went down to the 295's, it is a noticable difference but not huge. I have 3.73's and I tow 10,000 lbs about 20K miles a year and it towed fairly well, but it does better with the 295's and gained some mileage back towing.

Trinity

Suns_PSD · 03-03-2005, 12:56 PM

I spent some time using some long ago forgotten Algebra skills and I managed to put this formula together to calculate ACTUAL RPM w/ different gear ratios and such.

RPM = Overdrive ratio of tranny x mph x gear ratio x Revs per mile / 60

Overdrive ratio = Overdrive ratio for my 4R100 tranny is .71. Of course you can calculate RPMs for any gear that you would like. This can be useful for the manual guys.

mph = Whatever speed that you would like to know your RPM for stick in here. I tested speeds of 70 & 75 mph.

gear ratio = Stick the considered gear ratio in here. The options I was considering for my new 37s were the 4.10s and the 4.33s.

Revs per mile = The hell w/ just guessing by using 35s or whatever. I looked up the actual Revs per mile that the manufacturers list for their tires on their websites under "sizes & specs." This is MUCH more accurate and it REALLY changed the results of this calculation.

For instance, w/ 35" BFGs (revs/ mile are 600 for the 35x12.5x16.5) and with 3.56s you would be turning 2428 RPMs!!! There goes the fuel economy.

After looking and doing some simple calculating, for me, the 4.10s are EXACTLY right for my truck w/ the 37s I'll be running.

The truck will turn 1919 RPMs at 70mph and 2056 RPMs at 75mph which should be about perfect for fuel economy and a bit less of a gap between 3 & 4th gears than my current 35s w/ 3.73s.

So I will have a bit slower RPMs (faster gearing) than w/ stock tires w/ 3.73s but a bit faster RPMs (slower gearing) than my current 35s w/ 3.73s. It should be great!