Dana HP30 vs LP30

[Chris]

The misinformation in the brake industry is outrageous.

Rubber flex hoses are rated at 3000 psi and have to be or they aren't allowed to be DOT compliant. A hose can't be rated at that pressure and bulge under pressure. And yet every or just about every seller of them says they will improve pedal feel because they don't expand as much under pressure. I've actually tested both side x side at 2500 psi and they bulge or expand exactly the same amount, or slightly less than .001".

S/S flex lines are worse about being resistant to vibration and kinking. I see them all the time with the braid broken and split at the juncture of hose to fitting due to improper or nonexistent strain relief. I have never seen a rubber flex hose do the same thing.

There is also another myth about flex hoses that folks live by and that is you can't hang a caliper by the hose or you will damage it which is pure BS. If a hose can handle being shaken thousands of times per mile by the suspension hitting bumps on the highway and offroad, can resist almost 3000 psi before bursting, hanging a 5 lb caliper from it won't hurt a thing. Look at it when you hang it and if it isn't trying to kink the hose where it enters the banjo fitting, don't worry about it. That is certainly far less likely to damage anything than using the crimp tools they sell to pinch off a line so it won't leak fluid while you are working on the system.

Another myth is residual pressure valves for drum brakes.

Here is the typical ad for one and they are all very similar.

Drum brakes require a 10 lb. residual pressure (RPV10) to counteract the spring tension in the drum system which tends to pull the shoes away from the drums. This will give you a longer pedal travel and "spongy" brakes. The residual valve holds a pressure keeping the shoes near the drums giving a higher firmer pedal. Also required a metering valve (PVM) to the front (the metering valve prevents nose dive).

Let's do a little math, shall we? 10 psi into a wheel cylinder with a bore of roughly 1 1/8" has an area of just about 1 square inch which is 10 pounds of force against the return springs that pull the shoes away from the drum. The average force of drum shoe return springs as can be verified by anyone who has ever changed brake shoes is about 10 times higher than the force a RPV can exert. In other words, the RPV does and can do nothing to reduce pedal travel because it can't move the shoes off of the anchor pin not to mention that you wouldn't want it to anyway. The style of drum brakes we typically see in vehicles is known as servo or self energizing in that if the drum shoe return springs weren't strong enough to pull the shoes away from the drum, they would just keep self applying until the drum locked up. It is only the return springs that allow you to modulate the brakes so even trying to defeat that with any type of added valve is a fool's errand and taking advantage of folk's ignorance by ads like above makes you an idiot.

You need a bigger master to make your existing brake system work better because bigger is better, right? Nope, all bigger does is reduce pressure into the system and make your problems worse.

There are more but I'm tired of typing.

I'm glad you set that straight in regards to the brake lines.

The misinformation in the brake industry is outrageous.

Rubber flex hoses are rated at 3000 psi and have to be or they aren't allowed to be DOT compliant. A hose can't be rated at that pressure and bulge under pressure. And yet every or just about every seller of them says they will improve pedal feel because they don't expand as much under pressure. I've actually tested both side x side at 2500 psi and they bulge or expand exactly the same amount, or slightly less than .001".

S/S flex lines are worse about being resistant to vibration and kinking. I see them all the time with the braid broken and split at the juncture of hose to fitting due to improper or nonexistent strain relief. I have never seen a rubber flex hose do the same thing.

There is also another myth about flex hoses that folks live by and that is you can't hang a caliper by the hose or you will damage it which is pure BS. If a hose can handle being shaken thousands of times per mile by the suspension hitting bumps on the highway and offroad, can resist almost 3000 psi before bursting, hanging a 5 lb caliper from it won't hurt a thing. Look at it when you hang it and if it isn't trying to kink the hose where it enters the banjo fitting, don't worry about it. That is certainly far less likely to damage anything than using the crimp tools they sell to pinch off a line so it won't leak fluid while you are working on the system.

Another myth is residual pressure valves for drum brakes.

Here is the typical ad for one and they are all very similar.

Drum brakes require a 10 lb. residual pressure (RPV10) to counteract the spring tension in the drum system which tends to pull the shoes away from the drums. This will give you a longer pedal travel and "spongy" brakes. The residual valve holds a pressure keeping the shoes near the drums giving a higher firmer pedal. Also required a metering valve (PVM) to the front (the metering valve prevents nose dive).

Let's do a little math, shall we? 10 psi into a wheel cylinder with a bore of roughly 1 1/8" has an area of just about 1 square inch which is 10 pounds of force against the return springs that pull the shoes away from the drum. The average force of drum shoe return springs as can be verified by anyone who has ever changed brake shoes is about 10 times higher than the force a RPV can exert. In other words, the RPV does and can do nothing to reduce pedal travel because it can't move the shoes off of the anchor pin not to mention that you wouldn't want it to anyway. The style of drum brakes we typically see in vehicles is known as servo or self energizing in that if the drum shoe return springs weren't strong enough to pull the shoes away from the drum, they would just keep self applying until the drum locked up. It is only the return springs that allow you to modulate the brakes so even trying to defeat that with any type of added valve is a fool's errand and taking advantage of folk's ignorance by ads like above makes you an idiot.

You need a bigger master to make your existing brake system work better because bigger is better, right? Nope, all bigger does is reduce pressure into the system and make your problems worse.

There are more but I'm tired of typing.

So glad you cleared this up, especially in regards to the brake lines. All I hear about on any automotive forum is how you should be running stainless steel braided brake lines for better braking performance.

This is especially rampant on performance car forums, as well as motorcycle forums. I've owned a number of sport bikes, and one of the first things people always tell you to do is upgrade your brake lines, since the stock ones, "expand under pressure".

I knew this was complete bullshit, but how do you tell these guys their wrong, when they are so consumed by the marketing, that they'll argue it with you til' death that they're right and you're wrong.

I guess you just don't. You let them keep on believing what they want to and wasting their money.

It doesn't stop with brakes either. Apparently you need $400 'chain adjusters' to adjust your motorcycle chain to be accurate within 1mm on each side... It just doesn't stop.

The misinformation they spread with marketing annoys the crap out of me, but it must drive you mad!

 

[mrblaine]

I knew this was complete bullshit, but how do you tell these guys their wrong, when they are so consumed by the marketing, that they'll argue it with you til' death that they're right and you're wrong.

I guess you just don't. You let them keep on believing what they want to and wasting their money.

I built a test bench with a large electric actuator that pushes on a stock brake master and plumbed in 4 pressure gauges so you can see the pressure in and out of a TJ combo block. I can also hook up a brake line that I have dead headed into a cap or plug and can measure how much the line expands at any given pressure. When you show them that the line expands the exact same at the exact same pressures, it's pretty easy to prove them wrong.

It is very much like the snake oil nitrogen they sell you for your tires. Boyle's law states that all gases expand at the same rate for a given volume at each degree in temperature rise. Not to mention that if you filled your tires from a compressor with reasonably dry air in it, you already have 78% nitrogen in it anyway.

Then you get the "nitrogen is a dry gas" meaning it has no moisture in it. That's all fine and dandy but the way they separate out all the gases from each other absolutely negates the inclusion of any moisture whatsoever. They compress air and draw off the heat until they have liquid air. Because each gas boils off at a different temperature, all they do is slowly raise the temp of liquid air to the boiling point of each gas. Liquid nitrogen boils at about -320°F so there is no way there is any liquid water going along with the gaseous nitrogen or any other gas since the boiling point of most of them is well below the freezing point of water.

 

[Chris]

I built a test bench with a large electric actuator that pushes on a stock brake master and plumbed in 4 pressure gauges so you can see the pressure in and out of a TJ combo block. I can also hook up a brake line that I have dead headed into a cap or plug and can measure how much the line expands at any given pressure. When you show them that the line expands the exact same at the exact same pressures, it's pretty easy to prove them wrong.

It is very much like the snake oil nitrogen they sell you for your tires. Boyle's law states that all gases expand at the same rate for a given volume at each degree in temperature rise. Not to mention that if you filled your tires from a compressor with reasonably dry air in it, you already have 78% nitrogen in it anyway.

Then you get the "nitrogen is a dry gas" meaning it has no moisture in it. That's all fine and dandy but the way they separate out all the gases from each other absolutely negates the inclusion of any moisture whatsoever. They compress air and draw off the heat until they have liquid air. Because each gas boils off at a different temperature, all they do is slowly raise the temp of liquid air to the boiling point of each gas. Liquid nitrogen boils at about -320°F so there is no way there is any liquid water going along with the gaseous nitrogen or any other gas since the boiling point of most of them is well below the freezing point of water.

You need to record a video of that bench testing and put it on YouTube or somewhere that I can easily access it. That way any time these asshats try to argue that stainless steel braided brake lines don't 'expand' under pressure, I can just point them to the video for proof. You know how the Internet is, people will believe anything you tell them (well, most people at least).

I knew the nitrogen thing was a scam, that one didn't fool me. Of course I do find it amusing how tire places will try to up-sell you on it.

What we really need is a thread called, "Mr. Blaine's List of Marketing Scams".

It would literally just be a bulleted list of every well known marketing scam you see floating around their on the internet. I'm sure that would be a pretty long list... And I'll bet there would be a number of them that I personally didn't even realize were marketing tactics.

 

[mrblaine]

You need to record a video of that bench testing and put it on YouTube or somewhere that I can easily access it. That way any time these asshats try to argue that stainless steel braided brake lines don't 'expand' under pressure, I can just point them to the video for proof. You know how the Internet is, people will believe anything you tell them (well, most people at least).

It is even easier than that. Just tell the next person that intends to swap to S/S lines to take a pair of digital calipers and put them on the rubber flex hoses and have someone mash the brake pedal to the floor with the engine running. Record the expansion. Then swap the lines and do the same measurement with the new ones. It won't take long before they figure it out.

Don't get me wrong, we use a ton of braided steel lines but we do so for the sake of convenience. If you need a longer flex hose for longer suspension travel, it is not easy to hop down to the fitting store and have one made in any length you need like I can with S/S.

To be clear, neither the S/S or the rubber flex hoses expand much under pressure but they do expand a nominal amount.

 

[mouth]

I must be a rare bread.... been through 3 set of 4.56 gears for LP30.

 

[Jerry Bransford]

I must be a rare bread.... been through 3 set of 4.56 gears for LP30.

Did the same person install them and were all three the same brand? I ran 4.88 gearing in my locked previous LP Dana 30 running 35's on big rocks and had no problems.

 

[mouth]

Did the same person install them and were all three the same brand? I ran 4.88 gearing in my locked previous LP Dana 30 running 35's on big rocks and had no problems.

All were installed by the same person. Not sure of the brand. Always ended in a broken ring tooth. 35s, and a spartan locker. Could have been driving style and install...

 

[Jerry Bransford]

All were installed by the same person. Not sure of the brand. Always ended in a broken ring tooth. 35s, and a spartan locker. Could have been driving style and install...

Faulty R&P gear setup or driving style most likely, with possibly a cheap R&P adding to the problem. Time to stop using that installer and go with a good quality set of gears like from Revolution Gear. You're actually the first poster I've ever encountered on the forum with multiple R&P failures in a Dana 30 while running 35's.

 

[mrblaine]

I must be a rare bread.... been through 3 set of 4.56 gears for LP30.

I frequently chat with a few folks at axle and gear companies. There is a common theme amongst their opinions of warranties they offer regardless of length of time. IF a customer breaks something, they have no issue replacing it once. If it happens again, the customer needs to examine what he is doing and either change his preferred method of wheeling or build his rig to handle it.

If you took out 3 sets of gears in the same axle, then you were overpowering your equipment, or had a faulty installer. I've seen one broken Dana 30 gear set in 100's of trips in JV and we made the installer set it up again, and set it up tighter for less deflection under load and that gear set is still in use 10 years later.

That and if you trying to wheel any Dana 30 where wheel spin is required, you're gonna break it. You use the first break as the warning sign to go get something that can handle it.

 

[mrblaine]

All were installed by the same person. Not sure of the brand. Always ended in a broken ring tooth. 35s, and a spartan locker. Could have been driving style and install...

The LP 30 is being driven on the coast side of the gear. The good installer knows this and also knows that you need to set them up very tight and low in the pattern to limit the pinion gear walking out to the end of the ring gear tooth and snapping it off due to the angle of the ring gear teeth on the coast side. The 30 housing is notoriously flexible and it needs a good installer that knows this.

 

[mouth]

Ohhh I totally understand. In my part of the country tire spin is very frequent and the main issue of R&P breaks. That old "bump it one more time" saying.
I had read up and noticed the defection of the 30 when missing teeth on 2 R&P were exactly the same. I personally don't think they were set up right.

When I bought my JKU I went 5.13s. Setup was extremely tight and I steppes to 37s and never had a failure. But that's a whole different bread of animal.

 

[mrblaine]

Ohhh I totally understand. In my part of the country tire spin is very frequent and the main issue of R&P breaks. That old "bump it one more time" saying.
I had read up and noticed the defection of the 30 when missing teeth on 2 R&P were exactly the same. I personally don't think they were set up right.

When I bought my JKU I went 5.13s. Setup was extremely tight and I steppes to 37s and never had a failure. But that's a whole different bread of animal.

If you "totally" understand and you think the install was incorrect, then why the commentary about being the rare breed that has gone through more sets of Dana 30 gears than you should have especially when my first comments were specifically addressing the unsuitability of the LP or HP 30 for wheeling where wheel spin is needed?

 

[mouth]

If you "totally" understand and you think the install was incorrect, then why the commentary about being the rare breed that has gone through more sets of Dana 30 gears than you should have especially when my first comments were specifically addressing the unsuitability of the LP or HP 30 for wheeling where wheel spin is needed?

I'll admit I didn't 100% read all of the comments. Had I done that like i should I could of just not commented or said "hey I've broken 3 sets due to lack of setup or tire spin"..... my bad.

 

[TJim]

Long side axle tube is usually the one that gets trashed. If the lower mounts are bent sideways at all, there is a high risk of the tube being bent on the long side. After that, they are typically okay. If you want to check one, pull the axles and look through the tubes from both sides. Line up the circles so they are concentric to your eye. If you can't, it's bent.

Do not use the 27 spline Revo stuff, it's a waste of a good axle kit. The splines will be the weak point and you don't want the breakage inside the diff.

I know this is a REALLY old thread but I noticed you said that 27 spline Revolution axle shafts are not a good choice?

Which axle shafts would you recommend to build my current Dana 30. I want to install a selectable Locker and re-gear at the same time. I run 31" tires. The max tire Size I would possibly run in the future is 33".

 

[mrblaine]

I know this is a REALLY old thread but I noticed you said that 27 spline Revolution axle shafts are not a good choice?

Which axle shafts would you recommend to build my current Dana 30. I want to install a selectable Locker and re-gear at the same time. I run 31" tires. The max tire Size I would possibly run in the future is 33".

The discussion was about the big u-joint stuff. Standard u-joint in 27 spline is just fine. Makes no sense to put a big joint on axle shafts that are practically guaranteed to break at the inner splines.

 

[never monday]

The discussion was about the big u-joint stuff. Standard u-joint in 27 spline is just fine. Makes no sense to put a big joint on axle shafts that are practically guaranteed to break at the inner splines.

This because you want the easily replaceable and cheap ujoint to be the failure point.

Clarifying it for Jim.

 

[mrblaine]

This because you want the easily replaceable and cheap ujoint to be the failure point.

Clarifying it for Jim.

Not really and no I don't. I've never seen a u-joint failure that left the yokes in good enough condition to swap in a joint.

 

[hosejockey61]

I have the 27 spline 1350 revolution shafts. I can concur that the splines become the weak point. I asked revo about it and they said to get back with them if/when it breaks.

 

[SvtLdr]

I have the 27 spline 1350 revolution shafts. I can concur that the splines become the weak point. I asked revo about it and they said to get back with them if/when it breaks.

View attachment 244793

Hopefully it doesn't break on you. I'm interested to know if it does though.

 

[TJim]

The discussion was about the big u-joint stuff. Standard u-joint in 27 spline is just fine. Makes no sense to put a big joint on axle shafts that are practically guaranteed to break at the inner splines.

oh, okay! My bad!

I just going to use the u-joints that come with the kit. (photo)
Right?