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Amphibious HEMTT

Tire up date,

I let out air in the back tires to match the look of front at 5psi. Ended up with un measurable psi. (There was still some coming out, but not even one pound showing on the gauge) Here’s a pic.

AA788F3C-3484-4205-AA70-6F5716D3F534.jpeg


I sware some people wouldn’t even know it was low on pressure. Checked the tire temperature and they were averaging 86. Drove for about 15 miles and they were up to 110. Had it up to 50 mph on those doughnuts. Lol. I thought this thing was kind of mushy on the airbags, but nothing compared to no tire pressure. It would go over ruts in the dirt road like a sled. I could hear the ruts, but not feel them.

Anyways, I aired them back up to 25 in front and 18 in the rear. Took it back out on the road. I had it up to nearly 70 and it was pretty smooth. One thing I noticed was my steering gets pretty sensitive at 70. Definitely a two hands on the wheel kind of thing. Funny how 10 mph can make a big difference. Maybe it’s because the power steering pump is turning so fast. Do they have some kind of relief valve I can plumb in to make it turn only so fast? I doubt I will be driving that fast very long, but it would be nice if I could and not feel like I’m in a uncontrollable juggernaut.
 
The amount of driving you've put on this thing is fawkin awesome man. I haven't had much input on your tire testing, but I also prescribe to the idea that you just tested of deflating stiff tires and driving around to get the sidewalls moving as much as possible so hopefully that works. Your out of round numbers seem awesome.

As far as your power steering system goes I may be able to offer an opinion. First though, a couple questions. Is this a bone stock pump of aftermarket? Undersized pulley? Output fitting drilled out? What kinda RPM are you pulling at 70?
 
AgitatedPancake said:
The amount of driving you've put on this thing is fawkin awesome man. I haven't had much input on your tire testing, but I also prescribe to the idea that you just tested of deflating stiff tires and driving around to get the sidewalls moving as much as possible so hopefully that works. Your out of round numbers seem awesome.

As far as your power steering system goes I may be able to offer an opinion. First though, a couple questions. Is this a bone stock pump of aftermarket? Undersized pulley? Output fitting drilled out? What kinda RPM are you pulling at 70?
Click to expand...
I got the pump from PSC, but I think it’s a stock pump for Cummins. It is run off a gear, so no pulley. I don’t know anything about output fitting. I want to say the RPM is around 2200 at 60 and 2600 at 70. Would 300 make that much difference?
 
Yeah 300-400 RPMs can make a decent difference, The output fitting where your pressure hose connects to the pump has an intentional restriction of a certain diameter as part of the flow control device, the diameter of that orofice dictates at what flow volume the pump starts bypassing. So in stock form most pumps start bypassing at like 3gpm, which ends up somewhere around lets say 2k rpms for example, and stays around that flow volume from there to redline.. One of the common things people have done over the years is punch those out for "more flow" (me included lol), but all you're doing is raising that ceiling. So instead of bypassing at 3gpm @2k, its now bypassing at say 4gpm@3k. So where your steering feel should level out at 2k, it's now getting more and more sensitive as the RPMs raise from 2k to 3k.

Long story short, I'd drop that fitting size. Get that steering feel you like at 2k rpms to flatten out and maintain through the rest of the RPM range. I stepped mine back down and it made a HUGE improvement for that high speed hyper sensitivity. Some aftermarkets offer fittings with various different bore sizes, PSC would probably know what size that pump has based on the part number, and might even have a smaller fitting on the shelf for you to buy and swap in
 
AgitatedPancake said:
Yeah 300-400 RPMs can make a decent difference, The output fitting where your pressure hose connects to the pump has an intentional restriction of a certain diameter as part of the flow control device, the diameter of that orofice dictates at what flow volume the pump starts bypassing. So in stock form most pumps start bypassing at like 3gpm, which ends up somewhere around lets say 2k rpms for example, and stays around that flow volume from there to redline.. One of the common things people have done over the years is punch those out for "more flow" (me included lol), but all you're doing is raising that ceiling. So instead of bypassing at 3gpm @2k, its now bypassing at say 4gpm@3k. So where your steering feel should level out at 2k, it's now getting more and more sensitive as the RPMs raise from 2k to 3k.

Long story short, I'd drop that fitting size. Get that steering feel you like at 2k rpms to flatten out and maintain through the rest of the RPM range. I stepped mine back down and it made a HUGE improvement for that high speed hyper sensitivity. Some aftermarkets offer fittings with various different bore sizes, PSC would probably know what size that pump has based on the part number, and might even have a smaller fitting on the shelf for you to buy and swap in
Click to expand...

Can try a variable option.

Prince Mfg | Brands | www.surpluscenter.com

Prince Mfg,Brands, HAND PUMP HYDRAULIC SYSTEM Brand new PRINCE. Operates hydraulic presses, dumps, plows, snow blades, hydraulic tables, frame
www.surpluscenter.com
 
Here's a thread from a year or two back that ended up being an excellent discussion that fully opened my eyes to exactly how these things operate, Water if you ever want to see the finer details of all that goes on in the regulation of stock PS pumps it's absolutely worth checking out

CBR Steering Pumps - OEM Applications?

And it led me to make this displacement calculator so we could really get down to the nitty gritty of how and when flow regulation was coming into play

Steering Displacement and Speed Calculator

Dethmachinefab said:
Can try a variable option.

Prince Mfg | Brands | www.surpluscenter.com

Prince Mfg,Brands, HAND PUMP HYDRAULIC SYSTEM Brand new PRINCE. Operates hydraulic presses, dumps, plows, snow blades, hydraulic tables, frame
www.surpluscenter.com
Click to expand...
He definitely can as a backup option and it should serve the purpose nicely if he does, but the pumps have a flow control valve built in, tuning them is just more of a nuisance because you're tuning with a drill bit haha.
 
So you guys are saying I can just choke the output line? How about this? I could get that valve that Deathfab mentioned and put it after the hydro boost. I figure I don’t want to choke the fluid going to that.

Edit

After reading some of the link Agitated pancake posted, (Thankyou) it sounds like choking the output is not so good. At least that’s what Hydro dynamic said. I pretty well consider him to be the “god” of hydro stuff. If I understand him right, he said choking it will create heat. Better to have an external relief plumbed to the cooler. Not sure if that is overkill on a non racing rig.

let me ask a question, is the return line on the hydro boost a bypass? My simple brain is thinking that if I choke the flow after the hydro boost, it might bypass there instead of inside the pump. (Probubly doesn’t work that way)
 
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WaterH said:
I think the tires are 9000lbs. at 90 psi. The truck weighs just under 7000 lbs. (don’t know front and rear)

Someone else told me to let all pressure out and drive it around the block. I don’t think I want to do that, but maybe I’ll try 5 psi. The tires don’t actually go flat with no air pressure.
Click to expand...

The tires can hold 9k... Each... Damn.

I bet your truck is really light in the rear. But let's spitball 4k lb front, 3k lb rear.

Quick and dirty tire math...

(2k lb per front tire/9k tire capacity) = 22.222% of capacity

22.222% of 90psi = 20psi

(1500lb per rear tire/9k capacity) = 16.666% of capacity

16.666% of 90psi = 15psi

That would mean starting at 20psi front, 15psi rear, and adjusting a bit from there. If you can get more accurate scale weights for each axle we can adjust the math accordingly.

This also accounts for only the weight of the truck, not any loads carried or towed...

Edit: I just realized that those tires are 100lb/psi, and the math can be easily done from that. Derp. LOL
 
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WaterH said:
Ok, I went out in the shop and lowered the front tires to 5 psi. I lowered the rear tires to 3 psi. The front tires look low. (Not flat) the rear don’t really look low. Do you think I should just keep letting the air out till they look the same as the front? This is just for a few times around the block to get em hot. Should I drive them a specific amount of miles or should I go till a certain reading on a temp gun? I think maybe the temp gun, but what reading?

Probably going for the ride tomorrow because of weather right now. (Pouring rain)
Click to expand...

Drop a bit more in the rear, maybe 1 psi.

I don't like to drive them super low at speed or for too much distance. My "un-flat-spot" drives are usually well under 5 minutes at maybe 20mph max. More like 2-3 minutes around a couple blocks. Putting around the neighborhood. Or if you're rural, up and down a side road.
 
WaterH said:
So you guys are saying I can just choke the output line? How about this? I could get that valve that Deathfab mentioned and put it after the hydro boost. I figure I don’t want to choke the fluid going to that.
Click to expand...

That fitting is really there to create a pressure drop that the pump measures, which allows the flow control device to shuttle back and forth within the pump to regulate flow. So while it may be considered "choking" the flow out, its real purpose is tuning that pressure drop so the device operates at different intended ranges versus actually just creating a basic restriction that slows everything down. Then when it reaches that set point, the extra flow is recirculated within the pump to keep things moving.

The one concern I have with Death's device is it looks like it regulates flow by dead heading the fluid it doesn't want flowing versus recirculating it, I haven't experimented with that before and not sure what kind of complications it may induce. (at least if that's how the device works, need to look into it a bit more).

The idea of giving the hydroboost as much unrestricted flow as possible is definitely a valid idea. Just from the hip I would expect the brakes to already be pretty reactive in that 2000-2200 rpm range, but if the feel of the brakes gets notably better up in that 2600 rpm range (which also verifies the pump is hitting its flow ceiling higher than 2200), you could absolutely make any of your changes downstream of them to maintain that high RPM bonus performance
 
Yotota said:
The tires can hold 9k... Each... Damn.


Edit: I just realized that those tires are 100lb/psi, and the math can be easily done from that. Derp. LOL
Click to expand...

The tire ratting is actually 9300 per tire, but close enough.

Is that the way they determine the psi you should put in a tire? It makes sense, but I thought there was more to it than that. I guess I need to get the truck weighed again separate front and back.
 
AgitatedPancake said:
The idea of giving the hydroboost as much unrestricted flow as possible is definitely a valid idea. Just from the hip I would expect the brakes to already be pretty reactive in that 2000-2200 rpm range, but if the feel of the brakes gets notably better up in that 2600 rpm range (which also verifies the pump is hitting its flow ceiling higher than 2200), you could absolutely make any of your changes downstream of them to maintain that high RPM bonus performance
Click to expand...

Brakes seem to work great all the time, but I have to admit I never look at the rpms when I apply them.

Agitated, please go back and read my edit to that post and comment. I guess we were typing at the same time. I need to read the rest of your linked thread. I wish I had seen it when it was first opened.
 
Sure thing! The focus of that thread evolved from the initial question as I learned more, but great folks like Hydro and Radial added tons for us to learn from

WaterH said:
Edit

After reading some of the link Agitated pancake posted, (Thankyou) it sounds like choking the output is not so good. At least that’s what Hydro dynamic said. I pretty well consider him to be the “god” of hydro stuff. If I understand him right, he said choking it will create heat. Better to have an external relief plumbed to the cooler. Not sure if that is overkill on a non racing rig.

let me ask a question, is the return line on the hydro boost a bypass? My simple brain is thinking that if I choke the flow after the hydro boost, it might bypass there instead of inside the pump. (Probubly doesn’t work that way)
Click to expand...

Your interpretation is basically correct. These are fixed displacement pumps, so every rotation pushes a specific amount of fluid. So realistically up near redline, these pumps can be cycling 10-15GPM before regulation which we could realistically never make full use of. With that in mind, essentially all OEM pumps have two separate integrated devices - a pressure relief valve and a flow control valve. Both of those are built into that output fitting "shuttle" device (and can be tuned separately), and recycle the fluid they bypass right back into the pump body. Just from an intuitive perspective this is less than ideal because you're recirculating that fluid in a very short circuit within the pump which means the heat stays there as well. The counter point is that it's proven itself to be a reliable system for decades, and honestly I'm personally of the opinion that it is sufficient for 99% of builds.

Now what Hydro hits on a few times in that thread is basically taking your pressure and flow control devices and making them external, so you can put a cooler in the recirculation path. With that train of thought you delete those mechanisms from your pump (or get one of the PSC pumps that has no regulation at all), buy the external equivalent and hammer down. While theoretically superior, I haven't been convinced this provides enough benefit to be worthwhile for most of us. Even with the short internal recirculation path of most stock-config pumps, running a single PS cooler on just the fluid that makes it out of the output fitting has shown to be enough cooling to beat any heat buildup

But if you're restricting flow volume on a fixed displacement pump, that excess fluid volume has to go somewhere.

As far as hydroboosts, I actually don't have the experience (and haven't investigated the flow paths) enough to say with confidence. My guess is that the return hose is normally closed so you don't have freshly pumped fluid ready to do work being bypassed directly back into the reservoir. Then it starts returning fluid as soon as you start providing some input via the brake pedal and it starts using the fluid to do work
 
WaterH said:
The tire ratting is actually 9300 per tire, but close enough.

Is that the way they determine the psi you should put in a tire? It makes sense, but I thought there was more to it than that. I guess I need to get the truck weighed again separate front and back.
Click to expand...

There's a bit more to the math than that, and the rated load is added to the vehicle weight so the math is done for the full front/rear GAWR, but it's a good "close enough" spitball to get a baseline for a wheeling rig.
 
WaterH said:
The tire ratting is actually 9300 per tire, but close enough.

Is that the way they determine the psi you should put in a tire? It makes sense, but I thought there was more to it than that. I guess I need to get the truck weighed again separate front and back.
Click to expand...
I used this chart on page 12. https://www.toyotires.com/media/2125/application_of_load_inflation_tables_20170203.pdf

I don't have toyo tires, but you can see the math they are using in the table to kind of apply that to your tires and just do your own calcs. So far I have put 12k on the tires I thought for sure I was going to have to throw out. Honestly they got better and better the more miles I put on them once I got the pressure I was happy with. I ended up at 35 empty and 50 loaded.
 
MattS said:
I used this chart on page 12. https://www.toyotires.com/media/2125/application_of_load_inflation_tables_20170203.pdf

I don't have toyo tires, but you can see the math they are using in the table to kind of apply that to your tires and just do your own calcs. So far I have put 12k on the tires I thought for sure I was going to have to throw out. Honestly they got better and better the more miles I put on them once I got the pressure I was happy with. I ended up at 35 empty and 50 loaded.
Click to expand...

The Toyo Load and Inflation Tables are the bible of tire pressure, I do my math from them too.

But they only cover up to Load Range E in standard light duty truck sizes. For the 9300lb/tire rating we have here it's back to the drawing board.
 
I built a portable winch For the truck. If you want more detail, you can go to the thread “portable winch” I started. This is the finished item.

F18A988D-18B1-497E-AB16-699043342933.jpeg


On the end of the cables I installed a Anderson plug. Now I need a Anderson plug/socket on the truck front and back so I can use the winch. I found a Anderson plug mount on the bay. It’s made by a company in Australia. It looked not bad, so I ordered one.

EDEA290E-301D-42B6-AC07-CC49F4D9D82B.jpeg


The plug fits securely inside and it has a flip open cap when you want to use it. The back side has rubber stockade clamp that should make it water tight.

9AEB87C6-7D29-40C2-9E15-0225C026B759.jpeg


I had to make a bent plate to mount the mount. Ran in to my first problem here. When it’s all mounted securely, the edge is just slightly too close to put a plug in.

C2AC4E2B-FD03-4C0C-8ABD-A794864E28FE.jpeg


This only took about ten minutes to fix with a file, but why doesn’t it fit right off? Seems like I’m always altering products to suit. I understand if using it in a was that they didn’t intend, but I’m using this exactly as intended. Rant over.

I mounted it under my battery compartment so I don’t have to open it to use the winch or jumper cables.

A9936AB3-3ED4-445F-A958-1F79CA5AA5CE.jpeg


If you wondering why I didn’t put the mount just a little further away from the winch, there’s a simple explanation for it.

471D91A0-0906-4545-9BE0-5E10C5DEE41D.jpeg


After mounting the this one, I ordered another for the front.




Oh, and Don’t F-ing worry about the explaintion!
 
I like the mount for the Anderson plug. I have a rubber cover for mine and it works ok, but I like the idea of it being ridgid mounted under the truck instead of just hanging there.
 
Get a hold of Radial Dynamics for your steering stuff. I'm sure he'd work with you on this deal.
 
Dethmachinefab said:
Can try a variable option.

Prince Mfg | Brands | www.surpluscenter.com

Prince Mfg,Brands, HAND PUMP HYDRAULIC SYSTEM Brand new PRINCE. Operates hydraulic presses, dumps, plows, snow blades, hydraulic tables, frame
www.surpluscenter.com
Click to expand...

So I got this valve today. I don’t know if you have one or you just looked it up, but it is one heavy duty and high quality valve. I’m not sure how it will be installed. If I put it just after my one way valve, it will be a heavy chunk of steel hanging off the fitting on the hydro boost. I think I would have to support it some how.

I could replace the one way valve. I was talking to a tech at Howe and he told me I should not have a one way valve there anyways. Not completely in agreement. His point was if you take a hard hit the pressure has to go somewhere. I agree, but at least the hydro boost and steering pump are protected. I’m no expert.
 
I'll be curious how the new valve config works out but I have to admit with my current understanding of things (always open to a new point of view), I'm concerned about the way that style of flow valve restricts flow in our application. I did a bit more research to understand how that specific style of device works, and it basically just creates enough backpressure between the pump and valve to force the fluid to bypass through the pressure relief at the pump, in turn creating the desired reduction in usable flow by design. While it works well in industrial hydraulic circuits, it gives me concern in two specific areas - the hydroboost and the pump itself.

On the hydroboost, you're creating a permenant backpressure on the high pressure lines leading from the pump up to, and through, the hydroboost unit. Will having that backpressure on the output side act to reduce the work that can be done by the hydroboost? (The more I think about this, the more I think it would be alright as the hydroboost opens up a third unrestricted fluid return flow path when you use it, so it shouldn't care...maybe?)

But I do have a bit of concern about the new life the pump will be seeing. Our steering systems (boxes and orbitals both) are open center devices. So at idle they're continually flowing fluid through the whole circuit with no restriction beyond the cumulative resistance of all the lines, fittings, and passages it has to snake its way through so the system backpressure is pretty low until work is demanded by a valve. With this valve installed in the system there may be a little more restriction below the cutoff levels, but as you near and pass the desired cutoff level, it's providing enough backpressure for the pump to hit full pressure relief even when you're not asking anything of the system. So it's working hard and robbing horsepower anywhere above ~1500-2000 RPMS, even driving straight down the road with no hands on the wheel and not using the brakes.

And just for full honestly, I'm wrapping my head around the "what ifs" of this setup real time here, so I'm absolutely ready to learn something new if the logic is flawed anywhere! :beer:

Edit: Link to a cool informational vid that helped me wrap my head around this flow control vs others (blah, can't get it to not show the preview, lame I didn't want to muck up your build thread)

 
WaterH said:
So I got this valve today. I don’t know if you have one or you just looked it up, but it is one heavy duty and high quality valve. I’m not sure how it will be installed. If I put it just after my one way valve, it will be a heavy chunk of steel hanging off the fitting on the hydro boost. I think I would have to support it some how.

I could replace the one way valve. I was talking to a tech at Howe and he told me I should not have a one way valve there anyways. Not completely in agreement. His point was if you take a hard hit the pressure has to go somewhere. I agree, but at least the hydro boost and steering pump are protected. I’m no expert.
Click to expand...
I've not used one in a power steering setup. Used a few of them to control speed of functions on some equipment. Probably could have gone with a 3/8" or 1/4" one, they are a good bit smaller.

AgitatedPancake when the pumps running it hits relief psi because of gpm restriction fitting and she shuttle goes into bypass? My thoughts were this could replace the job of the orfice so you can dial in when the pump hits bypass. I'm not real familiar with auto ps stuff.
 
Dethmachinefab said:
AgitatedPancake when the pumps running it hits relief psi because of gpm restriction fitting and she shuttle goes into bypass? My thoughts were this could replace the job of the orfice so you can dial in when the pump hits bypass. I'm not real familiar with auto ps stuff.
Click to expand...

Hmmm, our PS systems essentially use the "pressure compensated flow control valve" shown in the second half of that video (which can also be purchased through surplus center I believe), which have the ability to regulate the flow not in direct correlation to the backpressure it creates like the others. Then we also have a spring loaded ball bearing pressure relief valve integrated into the back end of the "shuttle" to manage the pressure relief side of things. But I believe this allows the pump to flow up to, and past that volume cutoff point without creating too much inherent backpressure
 
WaterH said:
So I got this valve today. I don’t know if you have one or you just looked it up, but it is one heavy duty and high quality valve. I’m not sure how it will be installed. If I put it just after my one way valve, it will be a heavy chunk of steel hanging off the fitting on the hydro boost. I think I would have to support it some how.

I could replace the one way valve. I was talking to a tech at Howe and he told me I should not have a one way valve there anyways. Not completely in agreement. His point was if you take a hard hit the pressure has to go somewhere. I agree, but at least the hydro boost and steering pump are protected. I’m no expert.
Click to expand...
I'm just catching up on this thread for the first time and will admit that I have not read up entirely on what your steering system consists of but need to chime in that if you have not yet installed this needle valve, don't... and if you have, remove it. This type of valve is used to adjust flow rate in a constant pressure type of hydraulic system which is fundamentally different from how our steering systems operate. All that this valve will do in a steering system is waste energy, reduce the available pressure to use for steering/brakes, and generate a lot of heat.

There is such thing as an external adjustable flow control valve called a priority valve that you could use if you so choose to pursue the option of having an adjustable flow rate. It has three ports so that you have your inlet coming from the pump, then a "Controlled Flow" (CF) port which is your regulated flow rate (this can only be less than or equal to the pump flow rate) and an "Excess Flow" (EF) port which will output any flow in excess of the controlled flow. If the pump flow rate is under the control flow rate setpoint then 100% of your flow rate is going out the CF port and nothing out of the EF port. If pump flow is higher than the control setpoint then the CF is putting out your regulated flow and EF is putting out pump flow minus CF flow.

This is what you would be looking for: SAE 8 0-8 GPM Flow Control Wolverine by Prince Mfg W-1908-8 | Wolverine by Prince Mfg | Brands | www.surpluscenter.com

Your pump has essentially the same valve within it only the pump outlet fitting is CF and the EF is internal, allowing excess flow to recirculate right back into the pump body. To operate, each valve will be consuming roughly 100 PSI pressure drop to regulate the valve so they do generate some heat by their very nature. Your best option is to have the pump itself tuned to the target flow rate to eliminate redundant valves plus you would need an additional return hose using the external valve I linked to above.
 
RadialDynamics said:
I'm just catching up on this thread for the first time and ……..
Click to expand...

Thank you for responding. I was hoping for you or Hydro dynanmics to respond. I have not installed it. Mainly because I’m not sure I should fix something that really isn’t broke. At 70 mph, it’s a handful to drive, but I really don’t plan to drive there. At 60, it’s not bad. I was kind of afraid of making heat back at the pump. So I think your idea would be better If I decide to do it. Thankyou for the link. I hate trying to find stuff that I’m not sure is the right product.

I have a business trip to Delaware coming up. (About 700 miles) I might take the truck to test if a highway trip is feasible In it. Eventually, I hope to take the truck out west. It will not be with a timetable, so should have no need to go 70. The only real problem is once I get on the highway, I feel like I’m poking along at 60. Maybe I just need to stay off the interstate.
 
WaterH said:
The only real problem is once I get on the highway, I feel like I’m poking along at 60. Maybe I just need to stay off the interstate.
Click to expand...

This is how i feel when im in my big bronco. i feel like im poking along at 60, and she really wants to go faster, but 42s are kinda big for cruising along at 70 in commuter traffic. Much more enjoyable to take the back roads to work, and do 45 instead.
 
That’s cool! I wonder how it rides? I have to say, I’m really enjoying mine. The tires keep getting smoother. I guess the dyna beads are slowly working their way into the tires. Working out a few bugs in the electrical system. (Fan controllers and such) The steering seems to have cured itself or I just got use to driving it. I still rarely go over 60, but it’s not a big deal if I do.

I wouldn’t have believed it, but this thing gets as much attention as the Delorean. Every time I stop, I got people taking pics. I’ll be walking around in Lowe’s and some guy will come up and say “is that your truck out there”? Or I’ll come out and find people camped there waiting for me to ask questions. It really is mind blowing.

Havent done too much work on it. I got a new 1350 yoke coming for the front output on the transfer case. After I get that, I can order a new front driveshaft frame Tom Woods. I’m kind of scared of the homemade one on there now. It’s keeping me from taking it off road. Also, I want to get 1550 u-joint axles for the front. Those tires just look like so much leverage on the 1410s. (They are probably fine for the pussy wheeling I’m going to do.)
 
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