Tesla large drive unit in Ford Expedition

4616 Views 31 Replies 6 Participants Last post by DrGee, Apr 16, 2021

DrGee

Discussion Starter · Apr 10, 2021

Here's a motor mount question.
Can I put a Tesla LDU with the required custom half shafts, in the engine bay of a 4WD Ford Expedition? I would remove the ICE, transmission, prop shaft, rear differential and half shafts.
This would make it a 2.6 ton FWD SUV. Is this feasible? It would certainly be easier than fitting the LDU in the rear and cutting the rear subframe to mount it.

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brian_

· #2 · Apr 11, 2021

It might be feasible, although the space between the frame rails would need to be measured and compared to the drive unit width, and it probably won't be enough.

On the other hand, a front wheel drive Expedition doesn't seem like a desirable vehicle to me, and it is not at all clear how a useful amount of battery (100 kWh?) would be installed in it.

There is also a potential concern with overheating the motor, since it will be working harder than it would in any Tesla.

hallkbrdz

· #3 · Apr 11, 2021

FWD doesn't work well for heavy vehicles, especially starting from a stop uphill where everything is working against you. If the units will fit, I would look for a dual motor setup with the largest battery you can find. Expedition's are fairly wide, so you may be able to place the battery pack as-is underneath although you will give up some ground clearance.

DrGee

Discussion Starter · #4 · Apr 11, 2021

Thanks guys,
The front wheel drive question was my biggest concern. Cutting metal and welding is not within my current skillset. Perhaps I'll have to contract that bit out to a professional and have them put the LDU in the rear.
I've owned several Navigators/Expeditions and we have a Navigator now. I've taken measurements and I'm happy with the available space for batteries between the rails (two 60kwh packs from Chevy Bolt Pro's).

brian_

· #5 · Apr 11, 2021

hallkbrdz said:
Expedition's are fairly wide, so you may be able to place the battery pack as-is underneath although you will give up some ground clearance.

You can hope that, but reality is different. Any EV battery pack - especially one from a Tesla - is wider than the frame rail spacing of something like an Expedition, so the whole pack won't fit between the frame rails (even if there were not multiple crossmembers and other components in the way. Repackaging the pack would result in a much taller pack, and still a big problem to fit in. Hanging a complete pack entirely under the frame would be fine if you only drive on perfectly flat surfaces, but in the real world there wouldn't be functional ground clearance left.

There are reasons that all of the serious proposals for new electric pickup trucks use a completely different structure from any existing vehicle.

brian_

· #6 · Apr 11, 2021

DrGee said:
Cutting metal and welding is not within my current skillset. Perhaps I'll have to contract that bit out to a professional and have them put the LDU in the rear.

Since the Expedition already has independent rear suspension that's a possibility, but dimensions would still need to be checked and the fabrication work would be substantial.

brian_

· #7 · Apr 11, 2021

DrGee said:
I've taken measurements and I'm happy with the available space for batteries between the rails (two 60kwh packs from Chevy Bolt Pro's).

What's a "Pro" version of a Chevrolet Bolt?

DrGee

Discussion Starter · #8 · Apr 11, 2021

Oops!.. My miskate.. By Chevy Bolt pro, I actually meant Nissan Leaf Plus.

Reactions: 1

DrGee

Discussion Starter · #9 · Apr 11, 2021

brian_ said:
You can hope that, but reality is different. Any EV battery pack - especially one from a Tesla - is wider than the frame rail spacing of something like an Expedition, so the whole pack won't fit between the frame rails (even if there were not multiple crossmembers and other components in the way. Repackaging the pack would result in a much taller pack, and still a big problem to fit in. Hanging a complete pack entirely under the frame would be fine if you only drive on perfectly flat surfaces, but in the real world there wouldn't be functional ground clearance left.

There are reasons that all of the serious proposals for new electric pickup trucks use a completely different structure from any existing vehicle.

My plan was to build a battery box about 36 inches wide. The Expeditions' "ladder" is about 40 inches at the narrowest. There is space for a box 6 feet long and 11 inches deep. There are two cross-members that the box would sit on, but I'd have to add another to take the weight of the box.

Reactions: 1

DrGee

Discussion Starter · #10 · Apr 11, 2021

brian_ said:
Since the Expedition already has independent rear suspension that's a possibility, but dimensions would still need to be checked and the fabrication work would be substantial.

The fabrication is my main issue Brian. I wish I could build it as a FWD, like all those minivans (Chrysler and Dodge etc). They don't weigh 2.5 tons though...

hallkbrdz

· #11 · Apr 11, 2021

I was going to say, I don't see the pack height being an issue on a truck based platform, at least in most of the US. Build a frame around the pack, add a lift kit, and you can maintain the clearance.

brian_

· #12 · Apr 12, 2021

DrGee said:
I wish I could build it as a FWD, like all those minivans (Chrysler and Dodge etc). They don't weigh 2.5 tons though...

But they do, nearly. "Mini"vans are all over 4,000 pounds empty, although not as heavy as an Expedition.

Front wheel drive works; I just don't see the logic of buying an "SUV" with only two driven wheels, or a vehicle which gets rear-heavy when only moderately loaded that only drives the front wheels. I have a Toyota Sienna (FWD minivan), but I wouldn't go to great effort to build an electric one.

Two decades ago when Ford and GM built electric pickup trucks, they took different approaches, for the same reason:

Ford replaced the stock rear suspension in the Ranger Electric with a de Dion setup so they could put the motor at the back and leave the space between the frame rails clear for a huge battery pack;
GM used the complete drive unit of the EV-1 car to make the electric S-10 front wheel drive, leaving the space between the frame rails clear for a huge battery pack.

It seems to me that you are faced with a similar problem, and similar options.

Reactions: 1

brian_

· #13 · Apr 12, 2021

hallkbrdz said:
I was going to say, I don't see the pack height being an issue on a truck based platform, at least in most of the US. Build a frame around the pack, add a lift kit, and you can maintain the clearance.

Sure, if you are going to entirely custom-build a frame, modify the body to work with that frame, and use a drive configuration which does not require a shaft down the middle, a large battery pack can be incorporated.

mayes8229

· #14 · Apr 12, 2021

brian_ said:
You can hope that, but reality is different. Any EV battery pack - especially one from a Tesla - is wider than the frame rail spacing of something like an Expedition, so the whole pack won't fit between the frame rails (even if there were not multiple crossmembers and other components in the way. Repackaging the pack would result in a much taller pack, and still a big problem to fit in. Hanging a complete pack entirely under the frame would be fine if you only drive on perfectly flat surfaces, but in the real world there wouldn't be functional ground clearance left.

There are reasons that all of the serious proposals for new electric pickup trucks use a completely different structure from any existing vehicle.

Not only is a Model S pack much wider than the frame rails under an Expedition, it's nearly as wide as the Expedition itself! The track width of a Model S is only 1 or 1.5" narrower than the track width of an Expedition. It's a VERY wide car.

brian_ said:
Sure, if you are going to entirely custom-build a frame, modify the body to work with that frame, and use a drive configuration which does not require a shaft down the middle, a large battery pack can be incorporated.

In my K5 Blazer the transfer case, transmission crossmember, and exhaust all hang well below the bottom of the frame rails, so the "useable" ground clearance is about 6" below the frame. Most 4WD trucks are the same way. You could have a pack that's significantly taller than the height of the frame rails without really sacrificing much ground clearance. It wouldn't be very attractive to have a pack 6" below the frame all around the vehicle, but it wouldn't necessarily detract that much from the utility.

Reactions: 1

DrGee

Discussion Starter · #15 · Apr 12, 2021

brian_ said:
But they do, nearly. "Mini"vans are all over 4,000 pounds empty, although not as heavy as an Expedition.

Front wheel drive works; I just don't see the logic of buying an "SUV" with only two driven wheels, or a vehicle which gets rear-heavy when only moderately loaded that only drives the front wheels. I have a Toyota Sienna (FWD minivan), but I wouldn't go to great effort to build an electric one.

Two decades ago when Ford and GM built electric pickup trucks, they took different approaches, for the same reason:

Ford replaced the stock rear suspension in the Ranger Electric with a de Dion setup so they could put the motor at the back and leave the space between the frame rails clear for a huge battery pack;

GM used the complete drive unit of the EV-1 car to make the electric S-10 front wheel drive, leaving the space between the frame rails clear for a huge battery pack.

It seems to me that you are faced with a similar problem, and similar options.

I like the "SUV" in quotes, Brian. You're right. Most of these cars are really not SUVs. They are just big cars. I used to detest the idea of a 2WD "SUV". I've become more accepting of the design as a conversion, because of the cost and complexity of a 4x4 or AWD configuration. In fact, I'm "feeling" the GM S-10 design right now...

DrGee

Discussion Starter · #16 · Apr 12, 2021

mayes8229 said:
Not only is a Model S pack much wider than the frame rails under an Expedition, it's nearly as wide as the Expedition itself! The track width of a Model S is only 1 or 1.5" narrower than the track width of an Expedition. It's a VERY wide car.

In my K5 Blazer the transfer case, transmission crossmember, and exhaust all hang well below the bottom of the frame rails, so the "useable" ground clearance is about 6" below the frame. Most 4WD trucks are the same way. You could have a pack that's significantly taller than the height of the frame rails without really sacrificing much ground clearance. It wouldn't be very attractive to have a pack 6" below the frame all around the vehicle, but it wouldn't necessarily detract that much from the utility.

That's a valid point. In the Expedition/Navigator, the cross-members hang lower than the frame and they still leave 9 inches of ground clearance. Those trucks really ride high. Most models have a running board- I always use the running board to "climb" into the vehicle.

brian_

· #17 · Apr 12, 2021

DrGee said:
In the Expedition/Navigator, the cross-members hang lower than the frame and they still leave 9 inches of ground clearance. Those trucks really ride high.

Right, some of the crossmembers are low... but putting a pack below those crossmembers is obviously not feasible, and if you try to put it above them you have two problems:

the crossmembers have substantial height so the pack must be interrupted or indented for each crossmember; and,
if the battery pack is not interrupted for each crossmember it can only be installed from above, after removing the body.

In the Ranger EV, Ford used modified crossmembers which arched up above the battery pack, above the level of the frame rails.

mayes8229

· #18 · Apr 12, 2021

brian_ said:
Right, some of the crossmembers are low... but putting a pack below those crossmembers is obviously not feasible, and if you try to put it above them you have two problems:

the crossmembers have substantial height so the pack must be interrupted or indented for each crossmember; and,

if the battery pack is not interrupted for each crossmember it can only be installed from above, after removing the body.

In the Ranger EV, Ford used modified crossmembers which arched up above the battery pack, above the level of the frame rails.

True, unless the crossmember is bolted in from below like many trans crossmembers are. In the aforementioned Blazer I have one riveted crossmember just in front of the rear axle that hugs the floor of the body and the bolted-in trans crossmember. There are no others between the engine and rear axle (granted that my wheelbase is about 17" shorter than an expedition and other similar trucks).

I haven't seen many low crossmembers (except trans) in the area of interest on 4WD/RWD trucks unless they have a 2-piece driveshaft because the crossmember would be in the way of the driveshaft.

Reactions: 1

brian_

· #19 · Apr 12, 2021

DrGee said:
Oops!.. My miskate.. By Chevy Bolt pro, I actually meant Nissan Leaf Plus.

Thanks.

There is one version of the original Bolt, at 60 kWh. For 2022, the next-generation Bolt gets 66 kWh, and the 2021 model of the first generation already has this higher-capacity battery.

In the current generation of Nissan Leaf, the base version has a 40 kWh battery using the same style of modules as the original, and the Leaf Plus gets a deeper battery pack with differently-configured modules (using the same cells) for 62.5 kWh. I was surprised to see that the builders of the Toyota 4Runner 4x4 Race truck Leaf conversion have already found a 62.5 kWh pack in salvage, but it was apparently damaged in manufacturing, rather than already salvaged from a vehicle.

brian_

· #20 · Apr 12, 2021

DrGee, what year is this Expedition? I would like to try to find a frame illustration, and that's pointless if looking at the wrong generation.

Reactions: 1

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