I am going to purchase a set of used 4.10's from a friend with a low-mile truck.

My truck has 3.73's, and I want to make up for the 35" tires. I have a reputable person to install them...but not sure what else I will need OTHER than the gears themselves.

My truck has 70K on it, and I have never pulled more than 6K with it, and rarely tow ANYTHING. I do a lot of beach driving, 4x4 Hi and Low, probably 800-1200 miles a year. Otherwise, it is a daily driver with relatively easy use.

So, aside from 4.10 R&P Sets for front and rear, what else will I need?

Fluid obviously - how much?
Install kits? Which ones?
Anything else I should change/check/service while I'm in there?

Thanks
Shawn

 

Hey man, you allright? I can see if you put some 39's on or something and wanted 4.10's, but 35's? That is a waste of money and time. You are going to kick yourself in the rear if you go throough with this swap.

 

Alright?

I suppose...kick myself in the rear? Not sure why, especially if I can do it for a rather low expense.

Thanks for nothing,

SQ

 

You will need shim packs for the gears, and I would replace the pinion nuts and the ring gear bolts, locktite, new pinion seals, and if the bearings don't look up to par, bearings and races. If you are going to use the bearings that are on the gears, you need the races that went with them, so be careful pounding those out. I don't think there is a carrier difference between a 3:73 and a 4:10, but if there is, then you need his carrier.

 

You would be better off buying a new set. You will never get them set in the same ware pattern once you take them out. You might end up wth a premature failure.

But if you do go through it

Here you go check under rear end and you will find what you need.

www.Moesperformance.com

Call them and ask talk to bob he knows what he is talking about.

 

Not trying to offend you by any means, but I agree with SSMinnow. If you rarely tow, and only a few tons when you do, then you will not be gaining anything by switching to 4.10 gears other than maybe a faster 0-30' time. Your truck has plenty of power to turn the 35's and if you do any highway driving at all then you are going to see a decrease in mileage if you go over about 65 mph. My friend has a truck identical to mine but he has 4.10's instead of 3.73's and he redlines at 92 MPH, my truck does not redline before I hit the speed limiter at 108 MPH. (Of course these test were performed with professional drivers on a closed course.)

If you do decide to swap em' out, keep us posted and let us know how you like it afterword.

 

i agree.. if you cruse empty 90% of the time id have a hard time justifying it.. hell ive thought about swaping 373's into mine and i have rebuild kits and gears sitting here..
spend the $ on an upgrade that will improve low rpm performance and you will be good to go.

 

It seems that about 6 months ago there were several people who wanted to swap to 4.10's because they were getting 35's or already got 35's and were complaining about the lack of power, or the noticeable change.

There were several others who wanted to BUY their truck with 4.10's because they had intentions of installing 35's.

Now everyone says that 4.10's are not worth it?

Go away for a few months, and everything changes or what?

Correct me if I'm wrong.

Originally, I had a 31.6" Tire (265/70R17) with 3.73 gears.

I now have a 34.63" Tire (325/65R18) with 3.73 gears.

I increased my tire size by roughly 10%, thus reducing my overall gear ratio by 10%

If I increase my 3.73 axle ratio to 4.1, I'll basically be adding that 10% back into my final drive (3.73+.373= 4.103). This should yield the same final drive as I had when 'stock', thus providing original mileage (less the added wind and rolling resistance), 'original' power (seat of the pants, less the added wind and rolling resistance), and likely less wear/tear on the driveline caused by the lugging and lower RPM's that larger tires cause. The suspension wear is inevitable.

Is this not correct? I am honestly trying to figure this out, not being a smartazz.

It seems that the FIRST thing anyone should do if increasing their tire size is to change their gear ratio to match them. Years ago when I was lifting other trucks, this was the FIRST thing everyone told me. "Don't change those tires unless you plan to change the gears also!"

I KNOW my truck has plenty of power to turn the 35's. BUT, it the 35's still give a noticeable difference in power, shifting, etc...and logically I would think the 4.10's would correct this.

Anyone?

For the record, I've got two mustangs and an SRT6 Crossfire when I want to go 90+mph. The truck is made for 0-65, with a LOT of low-speed beach 'lugging', where the 4.10's and 'stock' final drive would likely help out a lot. Although I don't tow, going back to stock would benefit me, especially on the sand.

SQ

 

So would you recommend a Smarty on an Auto truck with 3.73's and oversized tires?

Wouldn't this basically create even more wear/tear on the 48RE?

More power in the engine doesn't help the fact that the truck is not geared correctly. Granted, it may not be as noticeable for the driver, but something is taking the abuse of the bad gearing.

I've honestly considered swapping my 325/65R18's back for some stockers...but they look too **** good

SQ

 

I am going to go the other way and say do it. It will be a heck of a lot easier on the tranny and if it is a stick shift on the clutch. You do not always gear for more power but to get your gear ratio back to close to stock with bigger tires. Makes life a lot easier on drive train components...

A competent gear man will/should be able to set the used gears up to work fine.

Best to get Master Kits for both, they have everything needed for proper set up.

 

it all depends on how you use the truck & how fast you drive
if empty as i said then 3.73 would probably be fine
34.5" tire @60=1550 a little low, but if you drive empty at 75-85, your just shy of 1800@70, and just over 2000@ 80. perfect for florida, texas, montana etc.. .

if you haul , or travel mostly @ or under 70 then yes 4.10 would be better

if your doing it for economy forget it. for performance? you'll pay $300+ for parts + labor. that kind of $ would go along ways twards a programer, exhaust, etc.

 

I'm rarely over 70mph in my truck...

My main reasoning for changing the gears is a little less stress on the auto and associated parts.

The performance, although worse than it was when it had stock tires, is still great. The mileage is still not bad for a 3/4 ton truck with 15/16 city mix, and 18-19 empty on the highway going the speed limit.

SQ

 

35's, while they are a step up in size over stock, I would hardly call 35's oversized.

 

They are oversized enough to change the final drive ratio and alter the performance of a 300hp/600ftlb truck...

SQ

 

Low expense is still more money than nothing. And you are wasting what little money you would have tied up in it. Even if you plan on hauling, I would still say keep the 3.73's with 35's. 4.10's and 35's, sorry, just no way man. MAYBE if you did 99% driving in town, I could maybe see, but if you are at 98% or less in town, stick with the 73's