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I wasn't referring to highway gears and eco hubs together, just that with stock gearing you really aren't able to drive fast enough for the tires balance/roundness to be an issue.
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ECO Hubs Who needs 3:07 gears?
- Thread starter Xengineguy
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Not true. The C7 trucks will hit 62-63 mph wound out. And depending on how the tire roundness and balance stacks up on each truck and tire pressure you can have pretty aggressive tire behavioral problems at about 45+ mph.
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I don’t think Eco Hubs have any effect on the pack break at all. It’s the RPM the engine is operating at when the pack break is applied/used. More RPM more breaking power. Down shift the transmission to increase breaking effectiveness.
Am I missing something?
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Yes. The 2:1 ratio. While rpm makes a difference, the effect of braking is exactly 1/2 half what it was before at any given rpm (ignoring gear efficiency)
Skyhawk13205
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The PAC brake isn't nearly as effective with the ECO hubs as it was before. It helps but not nearly as much as the transmission downshifting. The FMTV PAC Brake does have a tendency to seize up - mine did at one point and I had to remove it and "service" it aggressively in my bench vise quite a bit. Hasn't had an issue since but other guys have not had my luck it seems.:
I put about 8,000 miles on my truck before the hubs, and have about 3,000 on it with the hubs and I don't find that the transmission shift behavior needs any adjustment - other than being smoother because it better loads the converter, it's not significantly different other than which gear you are in for a given ground speed. If it shifted sooner it would put you below peak torque in the next gear and that would not be efficient. The transmission doesn't know or care what your ground speed (IE: gearing) is - it's shift behavior is governed by throttle input and input/output speed and it's programming is based on engine specs - peak torque, governed redline, etc. In the Allison software it doesn't even show ground speed that I have found. I have poked around in the software quite a bit and not found anything that I thought would be useful to change....... have contemplated seeing if I could set the PAC brake to stay engaged down into 2nd gear but as I noted the PAC brake is much less effective with the ECO hubs so I haven't bothered. You almost didn't even need the service brakes with the reduction hubs and the exhaust brake but now it just gives you a gentle drag when it engages.
I've done four complete ECO hub installs - two 4x4 and two 6x6 and none of them leak from anywhere using my sealant of choice:
It seems like driving with the 2:1 reductions hubs is like flying with your flaps down, it provides some lift benefits but it produces a lot of drag. Once it is cleaned up the airplane becomes faster but more slippery and is harder to slow down.
The pac brake is less effective because the truck has less resistance without the 2:1 hubs installed.
ramdough
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My understanding is that when you let off the accelerator pedal, the pac break causes a significant blockage (not 100%) of the exhaust, then forces a trans to down shift to raise RPM. The engine in effect is trying really hard to pump a bunch of air through a restrictor. The faster the RPM, the more braking.
I thought the pac break forced transmission into 3rd. If you could reprogram the system to use 2nd when you have ECO hubs, would it balance out (I did zero math here…. Just shooting from the hip).
Maybe someone who knows more can comment.
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I thought the pac break forced transmission into 3rd. If you could reprogram the system to use 2nd when you have ECO hubs, would it balance out (I did zero math here…. Just shooting from the hip).
Maybe someone who knows more can comment.
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That still would be about half the braking force. While rpms might match the 2:1 torque increase is not longer there
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I would think all you would need to do to make the pac break more effective is to increase RPM. Like downshift, 2000 rpm with
Eco hubs is the same as 2000 rpm with reduction. For the same road speed you will be in a different transmission gear.
Flaps up or down ??
Eco hubs is the same as 2000 rpm with reduction. For the same road speed you will be in a different transmission gear.
Flaps up or down ??
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I can attest to that!
Ronmar
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Probably less than half as effective. Just like loosing the 2:1 halves the thrust provided by the tires for a given amount of torque applied, it reduces braking thrust Also. As noted lowering the RPM also makes it less effective, so you must up RPM and ratio to regain some of that effectiveness.
Dropping to 2nd is not an option. No Torque converter lockup in 2nd, so no ex brake in that gear As I expect the TC would just freewheel away any gearing gains
Cant have it all our way I guess
As mentioned the 3116 didn't even have one, and I am sure it still helps, but you will need to down the gear to 3rd if it doesn’t already head there when ex brake is selected…
Dropping to 2nd is not an option. No Torque converter lockup in 2nd, so no ex brake in that gear As I expect the TC would just freewheel away any gearing gains
Cant have it all our way I guess
As mentioned the 3116 didn't even have one, and I am sure it still helps, but you will need to down the gear to 3rd if it doesn’t already head there when ex brake is selected…
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The pac brake works just fine for me with the ECO hubs. Main difference is It Punks out a little sooner than it used to as 3rd gear is faster than it used to be. So where I feel like it used to stay on down to below 20mph, now it’s pretty much done for by 30-35ish. It would be great if it could be used in 2nd. I still rarely used my service brakes and descending grades with my M1082 is just fine. The tranny is very aggressive at downshifting so It keeps those RPMs up…
DeMilitarized
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If you manually down shift and increase the rpm you will increase the cfm of air being forced into the pax brake thus increasing baking force.
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DeMilitarized
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In the Allison software there is a target downshift point on the wtec III. If you have the software you can access the tcm and tell it to go to 2nd but that is only the target downshift gear. It will try to shift to that gear as fast as possible. Problem in the mtvr is the c12 will overspeed when using the Jake brake to 2300 rpm and risks blowing a hole through the block so you set it to 5th gear. Doing this keeps the engine from aggressively downshifting through 4 gears quickly. Your mileage may vary on lmtv.
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I finally bit the bullet and got a set of hubs. I have a 3116 225hp so I was worried I would lose too much power/torque. I did some 0-50 ( won't run 60 lol) runs on flat ground and on a hill start before I installed the hubs. 0-50 was 30 sec on flat ground and up the hill was 0-35 in 28 sec. It would not get above 35. I haven't retested up hill yet but flat ground is now 0-50 in about 25 sec. It cruises effortlessly at 50 and jumps ahead when changing gears from 4 to 5th. I can defiantly feel a loss of torque at low speed so difficult terrain like sand will be interesting to try. 1st gear ( low) feels more like second did before the eco-hubs. Like others have said, it coasts a lot more so you. do rely a bit more in the brakes but I think the brakes work better. You don't have the pull of the engine to brake against when coming's to a stop. I've only driven about 40 miles so far but around town it keeps up with traffic and is more enjoyable to drive I'll be adding a 3000lb habitat to it in January. I'm curious to see how it drives with a load. I see people asking for a video on the install so I did one. It's the first video I've ever made but hopefully it helps someone.
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Great video, and nicely shot! I really like how you zoomed way in on what's important and sped up repetitive things that we don't need to see at real time! A lot of people that make tutorial videos don't understand the purpose of the video or how much should be in the scene of the camera. They may have it zoomed out too wide so that you can barely see the important thing, or show the same exact steps in real time of multiples of the same item.
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A few more miles down the road since the switch. Still happy and enjoying a totally new truck. Here is a video cruising down the interstate at 75 with the windows open—
I just noticed in another guy’s video his lock ring was at least twice as thick as what I received. That is the only part I’m concerned about. I’m worried the thin ones I got won’t be strong enough to hold the wheel bearing nut from backing off over time. What do you guys think?
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hmmm. My lock rings match yours and I noticed in the Youtube video they are also heftier.
I am no engineer, though the amount of force on the lock rings from properly pre-tensioned bearing nuts should be small. Someone with more expertise will chime in—
I am no engineer, though the amount of force on the lock rings from properly pre-tensioned bearing nuts should be small. Someone with more expertise will chime in—
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I've used both the old style and new. The new thinner version is perfectly adequate. All it does is grip the splines to keep the nut from sliding downhill on the very slightly angled helical plane that is the threads. It's like a wheel chock on a driveway angled at 1 degree - you could do the same with a steel toed boot. It's just there to stop it from *starting* to move not hold back any serious forces.
It works on geometry as much as anything. Look up the video Nord Lock made on how their washers work. They hold back all kinds of vibration but actually take *less* torque to loosen vs. a standard "lock" washer. Because they don't work by brute force. They work by geometric advantage.
It works on geometry as much as anything. Look up the video Nord Lock made on how their washers work. They hold back all kinds of vibration but actually take *less* torque to loosen vs. a standard "lock" washer. Because they don't work by brute force. They work by geometric advantage.
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Had one of the clamps strip today oddly just a tiny sliver of thread came out, almost like too large of a tap drill used. Not saying that's the case but that's the behavior I've seen from that. Made a mod to the clamp with a nut on the other side (I will also deform threads "Bubba threadlock" so it can't separate and get into the wheel bearing).
oddly just a tiny sliver of thread came out, almost like too large of a tap drill used. Not saying that's the case but that's the behavior I've seen from that. Made a mod to the clamp with a nut on the other side (I will also deform threads "Bubba threadlock" so it can't separate and get into the wheel bearing).
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