Hemi Truck Club banner

4.56 swap

10K views 82 replies 15 participants last post by  HEMI SPORT 
#1 ·
Well my engine isn't even broken in yet and I'm already planning my next mod. I've had a lot of people suggest 4.56 gears so I'm planning on doing it. I have two things holding me back, installation and highway mileage. I know, someone is gonna say "if you're worried about mileage buy a Prius" and that's very true. I just tend to drive a good bit of highway for my work, I'm a union electrical apprentice so I truly never know where my next job will be located. Also I don't like paying a shop an arm and a leg to install things I can handle. But I would also not enjoy screwing up my rear end. So my plan is buying a used rear end off a parts truck and changing the gears on the bench. I'll put that rear end in to see how I like the gears, and how bad my mileage gets. If I ultimately decide it's not worth it for me (which probably won't happen) or if I mess up terribly, I will still have my intact 3.92 rear end to put back in. If I end up loving it, I'll order another set of gears for my front end and tackle that. I plan on doing the rear first to be sure I like it, then the front. I did some calling around on a bunch of Craigslist posts and saw prices from $500-$800, but finally found a guy who said $100. So if it works out this weekend I'll try to drive out and pull it out. So any input? Will going from 3.92 to 4.56 be that big of a difference?
 
#35 ·
I guess that, just by the fact that you are going to a higher crankshaft to axle ratio, you're going to experience a slight increase in engine braking. i haven't noticed it myself, but with only 300 miles on my new gears, I'm driving it like a nun.
 
#37 ·
So I got my Motive 4;56 gears in the front on Saturday. It fought us a bit, the right axle did not want to come out, but was finally "persuaded" out with a blunted (ground down) air hammer. The gears went in smoothly. I used the original shims and after using the gear marking compound, saw that it was already aligned perfectly. They say 6 - 10 thou for backlash. Mine was at 5.5 thou so I left as is. Buttoned it all up and on the test drive (in 2WD) it was as quiet as a mouse. The roads were dry and so I got on a straight bit and slid it back into 4WD. Other than the 4WD light, you'd never know anything had happened. Smooth as silk, which ain't bad for a 14 year old, 192k + mile truck. I can drive along at 60mph and select 4WD with no noticeable noise or vibration. I'm gonna take it easy on both front & rear for another 300 miles and then change out the gear oil.
So incredibly pleased with this mod. Motive gears seem to be awesome. The truck is so much more responsive and the gas mileage has gone up 15% better, so the gears should pay for themselves in 964 years.
 
#39 ·
Well done!
 
#43 ·
4.56 in Dodge Ram = FFFFFFFFUUUUUUUUNNNNN TIME
 
#44 ·
After reading the posts here, I seriously considered the DTT, but my rear let go because of the infamous spindle nut backing off by itself. This wasn't a planned project and it was essentially dumped on me 4 days after Xmas (aka broke-as-hell week). Going to 4:56's was my main goal and while I was in there I replaced the LSD clutch plates. My wallet just couldn't run to a DTT too. That said, she rarely gets driven in anger anymore and the 35 x 12.50's find sufficient grip off-road to keep me happy.
4:56's really are one of the best mods to this truck.
 
#45 ·
The DTT is the only thing keeping me from having this done at the moment. Gotta save up that extra $450 on top of the gears and install kit.
 
#46 ·
It is very easy to install a ddt after the 4:56 gear is installed. The difficult part for me is to get the pinion shims and preload right. But when installing just the carrier it is simply an exchange of carriers. I have done ddt's in both red and the ram 2500.
 
#47 ·
Ok good to know. That shows my ignorance in gears haha. I figured it would be way easier to install at the same time. Maybe I will upgrade that at a later date and get these gears done sooner
 
#48 ·
You will just need check your backlash then swap the dtt into where the factory unit is then reset backlash back to same spec and double check pattern. Like stated the shins part is the tricky part but you can also go off factory shims normally work 9/10 times but still needs contact check and then lash set again. It’s a little maticulous but not hard to do.
 
#53 ·
I essentially did the same as you're going to do in that I replaced R&P, all bearings & seals, even the outer (wheel end) ones, but I just replaced the clutch packs in my LSD instead og going the DTT route. My truck is now 14 years old with 192K + miles. I can select 4WD at 70 mph and you can hear & feel absolutely no difference. So incredibly smooth.
 
#57 ·
Here's my 2 cents and I don't expect everyone to agree with me. The 4:56 isn't the best gear for every build. As horsepower goes up there is a point where 4:56 becomes too much and a 4:10 or 3:92 provides a better trap rpm. Street trucks need to have a broad power band. Something like 2500-6500. So each individual build is different, from engine, torque converter, tires, weight and gears. And type of power adder if used, each being different. So my opinion is stock to 500hp, 4: 56. 600+hp, 4:10. 750+ 3:92. Bottom line is be prepared to do a lot of testing.
I'm on board with 95% with Greg here, except I'm an RPM Junkie ..when it's useable.

What trans are you running? how stock is the engine, I see in your Signature you list your truck as SRT 8 Daytona, 6.1 or 6.4 ? or owner made ? ..there is no wrong answer .

If your running a stock 545, I'd go with the 4.56s or the 4.45s if you swapped over to a 518/46 than 3.92s would be good.
One thing is for sure that SRT-10 Dana needs to have the spider gears replaced if you plan on putting more than 550-600 Hp thru it....I love my DANAs but the SRT C-Clip axle needs some help https://shop.jtsvp.com/product.sc?productId=652&categoryId=176
 
#55 ·
Here's my 2 cents and I don't expect everyone to agree with me. The 4:56 isn't the best gear for every build. As horsepower goes up there is a point where 4:56 becomes too much and a 4:10 or 3:92 provides a better trap rpm. Street trucks need to have a broad power band. Something like 2500-6500. So each individual build is different, from engine, torque converter, tires, weight and gears. And type of power adder if used, each being different. So my opinion is stock to 500hp, 4: 56. 600+hp, 4:10. 750+ 3:92. Bottom line is be prepared to do a lot of testing.
 
#56 ·
Here's my 2 cents and I don't expect everyone to agree with me. The 4:56 isn't the best gear for every build. As horsepower goes up there is a point where 4:56 becomes too much and a 4:10 or 3:92 provides a better trap rpm. Street trucks need to have a broad power band. Something like 2500-6500. So each individual build is different, from engine, torque converter, tires, weight and gears. And type of power adder if used, each being different. So my opinion is stock to 500hp, 4: 56.
600+hp, 4:10. 750+ 3:92. Bottom line is be prepared to do a lot of testing.
----------------------------------------
DEFINITELY :iagree: The 4:56 works extremely well for probably 98+% of us...if you're seriously into the bigtime power and top-end traps then by all means different gearing would likely be beneficial...as mentioned - research & multiple testing trials is the key to your level of success :thumb:.
:GoodLuck1:
 
#64 ·
As for replacing the 545 read these 2 threads
http://www.hemitruckclub.com/forums/f120/a518-46rh-46re-47-48re-rebuild-17576.html
http://www.hemitruckclub.com/forums/f170/redtrucks-never-ending-tale-16015.html
Yeah it's Hemi started one for his 46RH swap that's also one to follow.

ok as for the Flange joint on the Dana, no one does it,..not that it can't be done, but I think no one's getting back to you about it because it's just not done....

...your best bet is to get a drive shaft with the yoke style u-joint.
 
#66 ·
Contact JTS and tell him what you want to do, that yoke will fit, but keep in mind the center line from Axle to U joint on the Dana is longer than the 9.25
https://www.shop.jtsvp.com/contactus.sc
 
#78 ·
Any specific info or tips on changing the front gears to 4.56? I’ve looked around for awhile and haven’t seen any specific writeup on it, only for the rear gears
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top