Builds fj60 going to EV FJ45 (2 Viewers)

[workingdog]

Okay, I need some help with math as I think about whether I'm going to dive in and change the drive train so that motors are driving the axles directly and there is no transmission or transfer case. I found out the master/slave ability of the Hyper 9 as designed for the motors to independently drive a right and left wheel, so in my case, they could set it up so the front is torque limited to be less than the rear.

Basics
So, I've got 4.18 gears.
Hyper 9's produce 120hp 173 ft/lbs torque - so total 240 hp and 346 ft lbs torque (at 0 rpm).
Hyper 9 can rev to 8,000 rpms, but is happiest 0 to 3,000.

Now, I was told the the Hyper 9's could not launch the EV without gearing help. Standing thought is you need 8:1. But, with the transmission in 4th (1:1), I can take off without any trouble. But that's with 4.18 (or about half) gearing in the diffs.

One thing the transmission and transfer case give me is lots of gearing options.
If I lose the transmissions, I'd lose a lot of that. However, I would put a gear reduction on each Hyper 9 - However, I'd have to be at a full stop to do it, as there's way to shift them together. But that's probably okay.

The Magnum under drive has ratios of 1:1, 1.96:1, 2.72, 5.33:1

That would give me, in combination with the 4.18 rear end, 4.18, 8.2, 11.3, 22.2 final ratios

So, if my math is right - and it rarely is the first time, then the following table lays out the speeds in each of the over drives options. Which seems pretty good.

So, am I right?

				rpm	distance in miles (40's)	speed (mph)		rpm	distance in miles (40)	speed (mph)
differential	underdrive	final ratio	​	hyper 9 rpm of 3000​			hyper 9 rpm of 6000
4.18​	1​	4.18​		717.7​	1.4​	85.4​		1435.4​	2.8​	170.8​
4.18​	1.96​	8.1928​		366.2​	0.7​	43.6​		732.4​	1.5​	87.1​
4.18​	2.72​	11.3696​		263.9​	0.5​	31.4​		527.7​	1.0​	62.8​
4.18​	5.33​	22.2794​		134.7​	0.3​	16.0​		269.3​	0.5​	32.0​

The rear motor has a hub on it already that mates to a GM flywheel. I assume I can make or get made something made that would allow me to bolt the underdrive straight to it (eliminating the shaft???).

 

[GLTHFJ60]

You need way more gear when crawling around than on the street. Put it on a trail and try to crawl around in 4th gear before you commit to eliminating the trans and tcases.

 

[Bripars40]

Okay, I need some help with math as I think about whether I'm going to dive in and change the drive train so that motors are driving the axles directly and there is no transmission or transfer case. I found out the master/slave ability of the Hyper 9 as designed for the motors to independently drive a right and left wheel, so in my case, they could set it up so the front is torque limited to be less than the rear.

Basics
So, I've got 4.18 gears.
Hyper 9's produce 120hp 173 ft/lbs torque - so total 240 hp and 346 ft lbs torque (at 0 rpm).
Hyper 9 can rev to 8,000 rpms, but is happiest 0 to 3,000.

Now, I was told the the Hyper 9's could not launch the EV without gearing help. Standing thought is you need 8:1. But, with the transmission in 4th (1:1), I can take off without any trouble. But that's with 4.18 (or about half) gearing in the diffs.

One thing the transmission and transfer case give me is lots of gearing options.
If I lose the transmissions, I'd lose a lot of that. However, I would put a gear reduction on each Hyper 9 - However, I'd have to be at a full stop to do it, as there's way to shift them together. But that's probably okay.

The Magnum under drive has ratios of 1:1, 1.96:1, 2.72, 5.33:1

That would give me, in combination with the 4.18 rear end, 4.18, 8.2, 11.3, 22.2 final ratios

So, if my math is right - and it rarely is the first time, then the following table lays out the speeds in each of the over drives options. Which seems pretty good.

So, am I right?

				rpm	distance in miles (40's)	speed (mph)		rpm	distance in miles (40)	speed (mph)
differential	underdrive	final ratio	​	hyper 9 rpm of 3000​			hyper 9 rpm of 6000
4.18​	1​	4.18​		717.7​	1.4​	85.4​		1435.4​	2.8​	170.8​
4.18​	1.96​	8.1928​		366.2​	0.7​	43.6​		732.4​	1.5​	87.1​
4.18​	2.72​	11.3696​		263.9​	0.5​	31.4​		527.7​	1.0​	62.8​
4.18​	5.33​	22.2794​		134.7​	0.3​	16.0​		269.3​	0.5​	32.0​

The rear motor has a hub on it already that mates to a GM flywheel. I assume I can make or get made something made that would allow me to bolt the underdrive straight to it (eliminating the shaft???).

Take this with a grain of salt. While at SEMA this year I talked with several EV retrofit companies. Most of them commented that when converting a truck/suv to electric that the transmission is necessary to prevent the motors from overheating.

I think you’ve spent a great deal of time and money to make your current setup work that I would see it through. If you hate it a year from now then start to change it then. I would try and find the best/quickest path forward with your current setup that will allow you to register it and start to enjoy it on the road more.

 

[workingdog]

why would a transmission keep the motor from overheating????

 

[GLTHFJ60]

why would a transmission keep the motor from overheating????

Low motor rpm equals tons of torque, but the rotor isn't spinning fast enough for the cooling fan to be effective enough for how many amps are going through it.

A similar problem exists in the vfd world when you're running a motor at lower than rated rpm with high load for a long duration.

The trans wouldn't cool the motor, but would allow the motor to spin fast enough to cool itself, while giving you the gearing derived torque you need.

 

[workingdog]

Low motor rpm equals tons of torque, but the rotor isn't spinning fast enough for the cooling fan to be effective enough for how many amps are going through it.

A similar problem exists in the vfd world when you're running a motor at lower than rated rpm with high load for a long duration.

The trans wouldn't cool the motor, but would allow the motor to spin fast enough to cool itself, while giving you the gearing derived torque you need.

Thank you so much for the beautifully clear explanation.

And thank you everyone for your input. I hadn’t made up my mind yet. I’m just trying to figure out the math.

 

[workingdog]

Okay, the main supports are all in place. I made these clamps that will work for now to clamp it to the frame supports.

Little lip on the back to located so it won't work loose.

And now that the 2x2's are in place, I realized that there's only 4" of up-travel to the one in the middle. Sigh. that was no something I had even worried about. And I can't move the cross member because the battery box is in the way.

All I can think of is to cut that one back to inside the tire and just let the the decking span. No idea, but it should be okay.

But, I was also looking at what kind of skirt I wanted to put on, and essentially I can't have any skirt because of the tire. So ... just some kind of rail that runs around the outside and curves up at the tire. I'll have to think about that.

 

[peesalot]

I would offer the load/surge conditions that will exist would be a concern with a direct drive. IMO the drivetrain/gears allows you to manage that impact where as the direct drive would put any backlash strain directly on the motor and coupler. The gears allow you to save electricity, on the direct drive you have to use electricity to overcome resistance whereas with the drivetrain the gears will help with that.

 

[workingdog]

Moving onto fenders. The deck is mounted to the structure. It's all just tacked in until I get all this figured out.

I stole the fender design from a flatbed manufacturer I found online. The fenders are just a bent profile of aluminum.

It's nice and stiff.

So, I placed them, and I like them in general. But, one problem is that to get them to extend all the way to the outside of the wheels, they are a few inches wider than the flatbed itself - which looks weird. I'm not sure what to do about that, other than to live with it. The flatbed is as low is it can be, so the fender has to be tight against it.

Edit: I think the best solution is to move the flatbed up 1". 1" won't make a difference in how hard it is to get on or off of the bed, but it will make the side apron look a lot better and allot it to be functional.

Otherwise, I think the front (and therefore the backs) look pretty good. I'm not sure if I should trim the sliders more so that they end before the fenders, or go ahead and let them run under. If I do trim the sliders then I have to re-support them and rearrange the disconnect bracket. but that's all doable. if I let the slider run under, then it will drive rocks into the tire instead of releasing them into the soft aluminum fender.

But, I think I can go ahead and trim the sections so I can tack the fenders together into a unit at about 125 degrees. I'm all setup up to TIG aluminum and I've been practicing, but I'm now where near ready for this.

And then, there's an apron with a piece of pipe as a rub and tie down rail I plan to have along each side to cover the 2x2 and the side of the decking up front, and do the same in the rear and transition into the rear bumper thing. But ... it's going to be interesting to stuff that in that small space. So maybe I have to rethink that and have the rub rail transition from the front, out to the fender, and then back in at the rear.

 

[workingdog]

Okay, trying to build the back/bumper. Not sure what to call the back of a flatbed, it's not really a bumpers.

I ripped out the back of a section of 2x2 aluminum and slipped it over the end of the decking.

And I have 1/4" plate cut by SendCutSend for the sides and back of the sides of the rear panel.

But, my aluminum welding is so bad, I can't even tack these parts together enough to see how it all sits together. It's like learning how to weld all over again. Nothing I know about MIG welding steel is any use of all. I'm useless. Anyway, the odds of this going together correctly are about .000001%

I'm going to not make a headache rack/bulkhead for now - no need. If I can get this back mocked up, then I can order the side apron/rub rail and then start ordering the pieces that make up the drawer unit that will occupy the middle. Should be cool. Ordering the parts out of stainless.

Can anyone recommend a good source of sliders for this kind of drawer? Or is what's available regularly online (at 500 lbs capacity) fine for this.

 

[workingdog]

Okay, the flatbed is an inch higher - and this is the electric brake booster out of a Tesla. I wish I had known about this originally. Would have saved hours and hours and hours of screwing around. I hope it fits. If not, the Model S one will and this one will go in the M37.

 

[peesalot]

More pics of elec. booster, how big is that thing compared to a early 70's dia. booster ? Any idea what the current draw is ? assuming its 12 V ?

 

[workingdog]

Okay, more pics coming. It's much smaller than the booster. Not sure on current draw yet, but I'll look into it. Yes, 12v.

The reason I'm encourage, it's out of a Tesla Model S, which is very heavy, and know from experience has amazing brakes, so I know it puts out enough pressure.

 

[archie73]

I’m curious the bore on the master. 90% sure I’m going to go ev on my f100 and starting to make wish lists for parts donors.

 

[workingdog]

Bore is 26mm. which is 1.024 inches. So, good size.

 

[peesalot]

I was thinking of it for the 40 as well.

 

[workingdog]

I have to get motivated to actually dive back in and put the 3rd master cylinder and booster on this. God, I hope the thread sizes line up. My only concern is the reserevoir is too high, but there's a version for the Model 3 that's much flatter. I'll post when I get into it. Maybe tomorrow.

 

[workingdog]

for @peesalot

Okay, here is the FJ80 master and booster side by side with the tesla - and I'm pretty sure it's going to fit. The old master is out, the vacuum pump and canister is next (yea), and then I can deal with getting the Tesla booster mounted and powered up.

 

[workingdog]

So, here is in, that was way too easy, for as far as I've gotten. It's the same bolt pattern as the jeep booster I had on there originally and the fork landed on the pedal like it was made for it, no modifications required at all.

But, both fittings on the master (which look like the same size) are bigger than either of what was on the FJ80 master, so I've got to figure that out. And, I need to buy a harness so I can get power to the thing.

But, you can see how much real estate it leaves you.

 

[workingdog]

So, found this guy who makes the harness for this thing. It's a little more complicated than I thought. There are two connectors and you have to use both of them. But, in the end, it's just Bat 12, keyed 12, and ground required.

Bosch iBooster Gen-2 Universal Wire Harness – Tulay's Wire Werks

Super nice guy - total geek.