4.88 vs 4.56 for V8?

[Drift Monkey]

I'm debating a bit before I order since I just finished my FJ e-locker axle swap (a topic for another thread).

I'm getting some low humming from the rear upon deceleration at certain speeds, so I'm moving forward a bit quicker with my re-gear plans.

I'm currently sitting on 295/70R17s (33.5") tires but plan on moving to the 315s once these wear out. I'm leaning 4.88s right now as I live in a hilly area and the gear hunting/lack of cruise control use on the highway is annoying.

I do mostly city driving with occasional ~2.5-3.5 hr highway trips every now and again. I'm adding weight by way of front/rear bumpers/tire carrier/sliders (waiting on front bumper - hopefully will ship put by the end of this week, sliders will be welded on this Friday) and eventually a winch and skid plates (pushed back a bit for re-gear funding).

I'm aware that I'll be running slightly higher with 4.88 on the highway with my current setup, but I think I can live with it. 2819 rpm (@80 mph) on the highway should drop to 2722 once I eventually move to 315s. I'd only be saving 185 rpm with 4.56 (2634 rpm) at the same speed on my current tires and 179 rpm with the 315s (2722 rpm vs 2543 rpm on 4.56) - doesn't seem too bad, but I'll defer to those of you who have re-geared here.

I just wanted to gather a little intel before I make my wallet even more unhappy.

 

[doofenshmirtz]

I'm debating a bit before I order since I just finished my FJ e-locker axle swap (a topic for another thread).

I'm getting some low humming from the rear upon deceleration at certain speeds, so I'm moving forward a bit quicker with my re-gear plans.

I'm currently sitting on 295/70R17s (33.5") tires but plan on moving to the 315s once these wear out. I'm leaning 4.88s right now as I live in a hilly area and the gear hunting/lack of cruise control use on the highway is annoying.

I do mostly city driving with occasional ~2.5-3.5 hr highway trips every now and again. I'm adding weight by way of front/rear bumpers/tire carrier/sliders (waiting on front bumper - hopefully will ship put by the end of this week, sliders will be welded on this Friday) and eventually a winch and skid plates (pushed back a bit for re-gear funding).

I'm aware that I'll be running slightly higher with 4.88 on the highway with my current setup, but I think I can live with it. 2819 rpm (@80 mph) on the highway should drop to 2722 once I eventually move to 315s. I'd only be saving 185 rpm with 4.56 (2634 rpm) at the same speed on my current tires and 179 rpm with the 315s (2722 rpm vs 2543 rpm on 4.56) - doesn't seem too bad, but I'll defer to those of you who have re-geared here.

I just wanted to gather a little intel before I make my wallet even more unhappy.

What's your current gear ratio? Stock?

I regeared to 3.90 LSD, so it's not even close to what you're considering (practically not a regear, really), but I will mention that the rpm range you're looking at is right where the exhaust really wakes up, at least in my vehicle, regardless of what exhaust mods I've done.

The most common advice I've seen is to recalculate to factory ratios based on your tire. Always round up to the closest ratio offered, and if you hit it on the nose (like 295s and 4.10 gears), round up if you've got extra weight. If you're running the stock 3.727 gears currently, I'd bet 4.56 is going to be plenty but it'll really depend on HOW MUCH extra weight you're adding.

Add the extra weight up and calculate it as a percentage of your curb weight.

Your 295s are only 9.2% larger than stock, and 4.56 is nearly 22.4% over stock. The 4.88s are 30.9%. That means 4.56 will net you near 13.2% excess power (not really, but that's the spirit) and 4.88 has an excess of 21.7%.

Are you going to be running an extra 10% curb weight, 20%? Check the number again with the 315s, too. This is not pure science by any stretch, but I always feel better if I can make math choose for me!

 

[Drift Monkey]

What's your current gear ratio? Stock?

I regeared to 3.90 LSD, so it's not even close to what you're considering (practically not a regear, really), but I will mention that the rpm range you're looking at is right where the exhaust really wakes up, at least in my vehicle, regardless of what exhaust mods I've done.

The most common advice I've seen is to recalculate to factory ratios based on your tire. Always round up to the closest ratio offered, and if you hit it on the nose (like 295s and 4.10 gears), round up if you've got extra weight. If you're running the stock 3.727 gears currently, I'd bet 4.56 is going to be plenty but it'll really depend on HOW MUCH extra weight you're adding.

Add the extra weight up and calculate it as a percentage of your curb weight.

Your 295s are only 9.2% larger than stock, and 4.56 is nearly 22.4% over stock. The 4.88s are 30.9%. That means 4.56 will net you near 13.2% excess power (not really, but that's the spirit) and 4.88 has an excess of 21.7%.

Are you going to be running an extra 10% curb weight, 20%? Check the number again with the 315s, too. This is not pure science by any stretch, but I always feel better if I can make math choose for me!

3.73, stock. Ah good point about exhaust noise. WHen does

The 295s are 33.5, so 10% larger than stock (30.5).

The 315s are 34.7, so 14% larger than stock.

I'm planning on maybe ~600 lbs static added weight after it's all said and done (I just added up roughly what i'm planning on - front bumper/winch, sliders, rear bumper/swing out, front/mid skid, fuel tank skid. roof rack). This is before loading down any people or equipment, although I am somewhat of a minimalist. For the trail, usually just a toolbox or two, spare parts and a cooler for water/drinks - not things I carry daily. This could expand into a little more stuff since I'll probably want to camp and stuff once the pandemic stuff dies down (if ever) but let's just talk static for now.

So looking at it the calculator, 4.30 is actually closest to stock w/34.7s - 1.3% lower, 4.56 is 7.2% lower, and 4.88 would be 14% lower.

If I use the static weight added as baseline (curb weight is 4,530 lbs + 600 lbs), the difference is already 12.5% and this is without factoring in a tad more unsprung weight from bigger tires (~4lb more per wheel). So according to you, I should round up here - 4.56 isn't quite enough to handle the projected weight difference whilst 4.88 gives me a bit of room to add weight (looks like ~682 added lbs over stock curb is the breakover limit before you crossover to beyond the capacity of the 4.88 gearing).

Just for fun, it looks like only extreme gearing would be able to properly pull the GVWL of 6005lbs (28% over curb weight) - 5.29 will get you close-ish 21.9% and 5.71 would give a whopping 29.5% but with a caveat of spinning at 3185 rpm @80 mph on the highway....LOL

Also using this formula - with my 33.5s right now, i'm running at a -9.4% power difference from stock tire size...pretty depressing to think about haha.

Thanks for laying it out that way, it makes sense to me - feel free to make any corrections in my logic/math here. I feel like i screwed up somewhere...

 

[rich dog]

Hows the pinion angle look? Might be something to look at for the rear end noise.

 

[Drift Monkey]

Hows the pinion angle look? Might be something to look at for the rear end noise.

Around the same angle as stock, I can try to get some pictures tomorrow of the angle. It could well be the preload or a dry bearing from sitting empty too long...long story short the guy who sold it to me casually "forgot" to mention he pulled the pinion seal before selling to me - it was a nice surprise after filling 2qts of gear oil when everything was all already buttoned up. I did the seal and tried to do the preload myself - it looks/feels right but the noise happens decelerating from around 50-55mph for maybe a couple mph then stops.

 

[doofenshmirtz]

3.73, stock. Ah good point about exhaust noise. WHen does

The 295s are 33.5, so 10% larger than stock (30.5).

The 315s are 34.7, so 14% larger than stock.

I'm planning on maybe ~600 lbs static added weight after it's all said and done (I just added up roughly what i'm planning on - front bumper/winch, sliders, rear bumper/swing out, front/mid skid, fuel tank skid. roof rack). This is before loading down any people or equipment, although I am somewhat of a minimalist. For the trail, usually just a toolbox or two, spare parts and a cooler for water/drinks - not things I carry daily. This could expand into a little more stuff since I'll probably want to camp and stuff once the pandemic stuff dies down (if ever) but let's just talk static for now.

So looking at it the calculator, 4.30 is actually closest to stock w/34.7s - 1.3% lower, 4.56 is 7.2% lower, and 4.88 would be 14% lower.

If I use the static weight added as baseline (curb weight is 4,530 lbs + 600 lbs), the difference is already 12.5% and this is without factoring in a tad more unsprung weight from bigger tires (~4lb more per wheel). So according to you, I should round up here - 4.56 isn't quite enough to handle the projected weight difference whilst 4.88 gives me a bit of room to add weight (looks like ~682 added lbs over stock curb is the breakover limit before you crossover to beyond the capacity of the 4.88 gearing).

Just for fun, it looks like only extreme gearing would be able to properly pull the GVWL of 6005lbs (28% over curb weight) - 5.29 will get you close-ish 21.9% and 5.71 would give a whopping 29.5% but with a caveat of spinning at 3185 rpm @80 mph on the highway....LOL

Also using this formula - with my 33.5s right now, i'm running at a -9.4% power difference from stock tire size...pretty depressing to think about haha.

Thanks for laying it out that way, it makes sense to me - feel free to make any corrections in my logic/math here. I feel like i screwed up somewhere...

No problem man!

With an extra 600lbs on the vehicle, that's 13.25% extra load (5130/4530=1.13245), and the 315s at 34.7 vs factory 30.6 are 13.4% extra. That's nearly 26% more load on the vehicle, plus the tire weight difference will be huge and unsprung weight to boot. 4.88s are probably actually the right fit for you. Gotta stress again that the math here is not at all scientific.

Bringing things back into perspective - all of this is simply attempting to restore the factory ratios by compensating/making up for other changes. If you're comfortable hauling 600lb+ extra weight baseline, then you aren't one to be concerned about factory gvwr - that's out the window, lol. Your vehicle should basically drive like nothing has changed (in spirit). With the "new" curb weight and the regear, it'll drive like a normal 4runner with no weight in it - thereabouts. When you load it up with gear, it'll behave like a normal 4runner that's loaded up. If you want it to behave differently than stock, adjust accordingly.

You yin and then you yang. You add weight, so you add spring weight and (should) add braking force to stop it - maybe gusset and reinforce any known weak points. You oversize tires, so you lift for clearance and regear.

The other factor not considered is that you can also add power in concert with adding more gearing. Gears are simpler, but power can also compensate for weight differences without running massive RPM to get there. Even just the 3 methods of seafoam will wake up some engines. Really all we've got for the v8s is intake, headers, y-pipe, and exhaust. There's some unicorn superchargers from URD and TRD, but those aren't plausible for most.

I will finally add that with how much lift you'll be running, the eimkeith panhard correction kit is really nice. It'll correct the geometry of the panhard bar, which will improve the roll center. Being lifted but not driving like it's lifted is really nice.

 

[Drift Monkey]

No problem man!

With an extra 600lbs on the vehicle, that's 13.25% extra load (5130/4530=1.13245), and the 315s at 34.7 vs factory 30.6 are 13.4% extra. That's nearly 26% more load on the vehicle, plus the tire weight difference will be huge and unsprung weight to boot. 4.88s are probably actually the right fit for you. Gotta stress again that the math here is not at all scientific.

Bringing things back into perspective - all of this is simply attempting to restore the factory ratios by compensating/making up for other changes. If you're comfortable hauling 600lb+ extra weight baseline, then you aren't one to be concerned about factory gvwr - that's out the window, lol. Your vehicle should basically drive like nothing has changed (in spirit). With the "new" curb weight and the regear, it'll drive like a normal 4runner with no weight in it - thereabouts. When you load it up with gear, it'll behave like a normal 4runner that's loaded up. If you want it to behave differently than stock, adjust accordingly.

You yin and then you yang. You add weight, so you add spring weight and (should) add braking force to stop it - maybe gusset and reinforce any known weak points. You oversize tires, so you lift for clearance and regear.

The other factor not considered is that you can also add power in concert with adding more gearing. Gears are simpler, but power can also compensate for weight differences without running massive RPM to get there. Even just the 3 methods of seafoam will wake up some engines. Really all we've got for the v8s is intake, headers, y-pipe, and exhaust. There's some unicorn superchargers from URD and TRD, but those aren't plausible for most.

I will finally add that with how much lift you'll be running, the eimkeith panhard correction kit is really nice. It'll correct the geometry of the panhard bar, which will improve the roll center. Being lifted but not driving like it's lifted is really nice.

Wow man, thanks for another detailed response. With all the numbers we've been speculating, I decided to email ECGS to see what they had to say. They agree with your initial assessment of 4.56 since the V8 makes alot more power down low than the V6 - they recommend 4.88 for the V6 guys. The benefit is to keep the highway rpms down - which is more important to me than I initially realized since I am planning on getting a full headers/dual exhaust system done down the line (with as much sound deadening as possible lol).

Really good perspective on how it will all come together. I will do headers/exhaust down the line, making 4.56 even more reasonable for me.

I am planning to do the eimkeith PCK and LLG down the line but I need to ask my local fabricators first since this axle was sold to me with a bent panhard bracket that i was unaware of when purchasing. It was a royal PITA to get the panhard to go back in because of this.

As you can see I had to push in pretty hard to get it to line up (after some hard hammering on the bracket to get it as a straight as I could) and I also broke a ratchet strap pulling the axle over far enough to bolt the frame side up (I got a nice sized cut on my hand for souvenir as well). Now I have to figure out if a PCK will even weld correctly to it or if I should get a new bracket welded on the axle first - I'm not sure where to even source the bracket. My last ditch is using my stock axle's bracket which is perfect, but that would mean probably losing out on the resale of the stock axle.

Between this and the fact that the seller sold the axle to me with no pinion seal, this project as been a small nightmare for me. Not having the pinion seal on is evidence that someone had opened and possibly messed with the pinion preload and the seller claimed it's only been sitting dry/empty “for a couple a months" (without mentioning there was no pinion seal in it) means my noise could be coming from preload, dry bearings or any number of things. Thus, I'm using this as an excuse to re-do the bearings and add a solid pinion spacer, but the sunk cost means I might as well regear while I'm at it, hence my asking about gears I suppose lol.

 

[doofenshmirtz]

Oof. Tough break on the axle swap!

Ya know, the eimkeith kit might actually make things easier to figure out the panhard bracket. It is designed to nest perfectly in that existing bracket, so it would give you a solid reference point for what needs to move where.

Glad you reached out to some real experts on the gearing, too.

On the exhaust, look into my post history on the helmholtz resonator / j tube for deleting any drone. It’s literally magic with math that works very similar to noise canceling headphones. Super easy to add to any fabricated exhaust and 100% worth it.

 

[Drift Monkey]

Oof. Tough break on the axle swap!

Ya know, the eimkeith kit might actually make things easier to figure out the panhard bracket. It is designed to nest perfectly in that existing bracket, so it would give you a solid reference point for what needs to move where.

Glad you reached out to some real experts on the gearing, too.

On the exhaust, look into my post history on the helmholtz resonator / j tube for deleting any drone. It’s literally magic with math that works very similar to noise canceling headphones. Super easy to add to any fabricated exhaust and 100% worth it.

Yeah, just my luck lol.

Keith actually suggested that I use his PCK as a guide and using heat and channel locks to try to bend it back in place before trying anything more drastic.

The other thought that occurs to me now is that my axle housing could also be bent. Keith and others have mentioned it as a possibility, even though the bracket is much weaker than the axle itself. Visually, to my eye, it looks straight, but I'm going to get some second opinions before I do any more work on it. If it's straight, PCK will be ordered asap! An alignment shop may be able to tell me if it checks out and I also have a fabricator friend who often works on axles that will take a look for me when I get my sliders welded on this Friday. It does drive straight as-is, so here's to hoping!

Yeah, I'm glad I did some searching around before ordering. I trust ECGS' recommendations too.

So my plan with the exhaust is DT LT headers into an X-pipe and 2 of the longest magnaflow mufflers I can find, then adding helmholz resonators, so it's funny you bring that up. The only part I'm worried about it calculating the length they need to be or if it's super critical that they are absolutely sized correctly. You mentioned the exhaust to get loud at a certain range - perhaps it can be tuned to drown out the drone at a certain highway cruising rpm?

 

[4RunnerAquasport]

[MENTION=117203]Drift Monkey[/MENTION] Obviously heat is going to be needed, but the channel locks needed would have to be pretty good size and then your limited to how much grip force you can apply. Thinking out loud here...what if you used vise grips and a piece 2" diameter metal tubing about 4' long to slide over the v grips. Then you might have a more controlled point of leverage to get it inline with the correction bracket.
Some big ass channel locks may be all you need, but I thought I'd throw an option at you. Good Luck brother, what a PIA. I hope it's the last of your BS problems with this axle, and it's not bent either.

 

[Drift Monkey]

[MENTION=117203]Drift Monkey[/MENTION] Obviously heat is going to be needed, but the channel locks needed would have to be pretty good size and then your limited to how much grip force you can apply. Thinking out loud here...what if you used vise grips and a piece 2" diameter metal tubing about 4' long to slide over the v grips. Then you might have a more controlled point of leverage to get it inline with the correction bracket.
Some big ass channel locks may be all you need, but I thought I'd throw an option at you. Good Luck brother, what a PIA. I hope it's the last of your BS problems with this axle, and it's not bent either.

Hey thanks for the idea - I'm willing to try anything at this point. I'll keep this in my "ideas" tool box and I'm sure my fabricator guy will have some ideas as well.

I hope so too, I'll be pretty heartbroken if I have to swap another axle housing...:redbrick:, much less FIND one.

 

[JuniorPigeon]

This thread makes me feel like I'm back in engineering school eep:

But I'm glad it popped up lol. I'm on 295s with a V8 currently and am considering bumping it up to 315s/35s. I think 4.56 would be my pick on ratio, even stock the V8 has some pep in it's step comparatively.

 

[Inv4drZm]

I've had 4.88s on 35's and a bunch of extra weight and would say it wasn't bad. And if power is what you are wanting it will have plenty. Maybe lost 1 mpg vs 3.73s. This is with my VVTI V8 w/ 5 speed. Drone wasn't any worse either but that probably depends mostly on exhaust. Not sure if one could tell a difference side by side with 4.56 and 4.88 but who knows.

Now with 37's and 4.88s its back to feeling a little slower but I can still use cruise control most of the time.

 

[Drift Monkey]

This thread makes me feel like I'm back in engineering school eep:

But I'm glad it popped up lol. I'm on 295s with a V8 currently and am considering bumping it up to 315s/35s. I think 4.56 would be my pick on ratio, even stock the V8 has some pep in it's step comparatively.

Hahahaha, tell me about it. So many variables. But yeah, 4.56 seems like a good pick unless you're not a daily driving it. Then it seems whatever is fine.

I've had 4.88s on 35's and a bunch of extra weight and would say it wasn't bad. And if power is what you are wanting it will have plenty. Maybe lost 1 mpg vs 3.73s. This is with my VVTI V8 w/ 5 speed. Drone wasn't any worse either but that probably depends mostly on exhaust. Not sure if one could tell a difference side by side with 4.56 and 4.88 but who knows.

Now with 37's and 4.88s its back to feeling a little slower but I can still use cruise control most of the time.

Interesting. Well the difference between both is couple hundred RPM but I'm thinking that it could actually make a difference (depending on exhaust setup).

I'm excited to gain the use of cruise control back either way lol.

 

[doofenshmirtz]

Yeah, just my luck lol.

Keith actually suggested that I use his PCK as a guide and using heat and channel locks to try to bend it back in place before trying anything more drastic.

The other thought that occurs to me now is that my axle housing could also be bent. Keith and others have mentioned it as a possibility, even though the bracket is much weaker than the axle itself. Visually, to my eye, it looks straight, but I'm going to get some second opinions before I do any more work on it. If it's straight, PCK will be ordered asap! An alignment shop may be able to tell me if it checks out and I also have a fabricator friend who often works on axles that will take a look for me when I get my sliders welded on this Friday. It does drive straight as-is, so here's to hoping!

Yeah, I'm glad I did some searching around before ordering. I trust ECGS' recommendations too.

So my plan with the exhaust is DT LT headers into an X-pipe and 2 of the longest magnaflow mufflers I can find, then adding helmholz resonators, so it's funny you bring that up. The only part I'm worried about it calculating the length they need to be or if it's super critical that they are absolutely sized correctly. You mentioned the exhaust to get loud at a certain range - perhaps it can be tuned to drown out the drone at a certain highway cruising rpm?

For the Helmholtz, I've got a j-tube that open ended and a straight tube that's capped on one end. Then I've got a slip-fit piece that joins them with clamps. This allowed me to do all my math, fit everything up, and then adjust by cutting tube or sliding tube further out the slip fit. First try was perfect, so I've never touched it again. I think mine was 26.5inches total, including the bends - my target was centered on 1900rpm. Make sure to have a slight down slop to the tube so that you don't get condensation buildup.

I used the chart floating around to pick my length and gave myself a couple inches to adjust longer or shorter. Find the start and end of your drone and target the average rpm. and use the chart. How long is your J-pipe / HelmHoltz resonator? | 2015+ S550 Mustang Forum (GT, EcoBoost, GT350, GT500, Bullitt) - Mustang6G.com

It may actually be best to weld up the whole exhaust with no 1/4 wave resonator, drive it for a day or two, then come back to get the resonator sized just right. Just design the exhaust with the resonator tube in mind from the beginning, obviously.