SalvageS10 Build Thread

[thingstodo]

I went out to determine why the wheels on the truck measure out just under 30 inches in diameter, for about 94 inches around, but the ev calculator shows me that one revolution of the tire is more like 87 inches.

So I marked the tires with tape, and the ground with tape to show the starting point. I inflated the tires to 32 psi cold and pushed the truck forward one complete tire revolution. The answer - 87 inches. So I went another revolution and checked the total distance - OK - my tape measure is too short for that. So I measured 4 more tire revolutions and measured each. The results were between 86.5 and 87.75 inches.

I guess the side walls of the tire must flex quite a bit. I used a piece of network cable long enough to go from the starting position to the ending position and measured it in 12 foot chunks. 87 inches is close enough. That gives 13.85 inches radius.

I guess the ev calculator was right.

That 87 inch circumference gives just over 728 revolutions per minute at 60 mph. Just under 2500 rpm at 60 mph.

So 70 mph would be 2915 rpm. The motor is rated at 1770 rpm. That would require about 99 Hz.

At 99 Hz the torque output from 120 foot-lb (40 HP) would drop to about 72.

The smaller effective diameter should make the acceleration better, but it may hurt at the top end.

[thingstodo]

I made up a lazy man's motor model. It is the bottom of my old central vacuum canister, with an empty container from a rather large bush that I planted last year.

The empty container is about 16 inches in diameter at the top, which is just slightly larger than the motor at 15.5 inches.

The central vacuum canister is about 15 inches in diameter. Stacking the two together, I get about 26 inches of length. That is just above the length of the motor (19.5 inches) plus the motor shaft (5.5 inches).

I taped an ice cream container (6 x 6 x 8) on the side of my 'motor' in the correct place to be the motor junction box. Just a bit larger than the 5.5 x 6 x 7 of the actual junction box.

I put this 'motor' into the top of the motor cavity of the truck and tried to get it out the bottom. The contortions were many and the effort was large. I didn't get the motor through the hole and out the bottom. In fact, the motor does not fit well into the space centered on the motor mounts. The motor junction box is in the way. I'd have to rotate the motor on its side, fabricate a base plate that has a 90 degree plate, like an L bracket, to have the motor fit and align with the motor mounts. I'd like to try this but it may stress my mechanical skills.

Mounting the motor offset from center would require a drive shaft/U joint ... perhaps another bearing ... DEFINITELY above my mechanical skills

But I have established that the electric motor has to go in from the top.

Next up - arrange the drive shaft, transfer case, transmission, and electric motor on my driveway. Take measurements from the truck and make sure that the driveway arrangement is accurate to the truck. Find out how much room there is between the motor and the transfer case. What size and orientation is required for the motor to couple to the transfer case. There may be CAD involved.

Pictures: 40 HP motor from the top, in my garage, with bad lighting
the second one is supposed to show the diameter is 16 inches including the mount
Then there is the rough model, length a bit longer than the motor and shaft
and the diameter on one end is 16 inches
I took a bunch more pictures of the motor junction box, how it hangs on the side of the motor, and how that compares with the ice cream container taped onto the side of the model - but even I'm not that interested. This is some pretty dry information! Even for pictures.

[thingstodo]

Don't panic - I'm not cutting anything.

I set out the drive shaft, the transfer case, the front drive shaft, and my 'model' of the electric motor on a flat surface (my trailer bed) and slid everything together. Then I measured the total length.

Then I measured the total length from the rear drive shaft universal to the front drive shaft universal beneath the truck.

I have about 25 inches more space in the truck than I thought I would. Not that I'm complaining, but I want to know where I messed up.

The drive shaft length matches, the bolt holes to mount the transfer case are still in the place where I did the measurements. It has to be closer to the front of the truck.

I can't find it. I read the tape measure wrong, or it slipped and gave me 25 inches shorter, or I just measured to a different place in the front engine compartment. The drive shaft universal is pretty easy to identify ... strange.

The transfer case measures a bit further from the front of the truck than I was expecting. About 2 inches. It is possible that the rear drive shaft was not slid as far onto the transfer case spline as it could go when I measured the first time.

The 27 inch transmission (I'm told that the transmission length is actually 26 inches, as measured from the front mounting flange to the rear mounting flange. Don't include the spline that sticks out) will almost fit. I have about 2 inches of interference with the electric motor's 25 inch length plus a 1 inch clearance to the rear of the air conditioning rad. The rad can be removed, it just hasn't been removed as yet.

The transmission is stamped F and 21. It is apparently a hydromatic transmission. If I could trim 2 inches in length, there would be no interference at all. But I need a transition plate that fits around the motor shaft and bolts to the transmission clutch plate. I guess I need a bit more than 2 inches trimmed. Maybe 2.5 inches.

I'll call a couple of local wreckers and see what is available for the S10. I'll write down some info on the ICE engine and the old transmission. I'll bring the VIN as well. That should be enough to find out what will fit, and how much it will cost me.

Then I need to lay everything out square and check the measurements again. I am OK with being out by and inch or two when the measurements are rough. 25 inches is kinda scary.

Using the 40 HP motor through a manual gearbox AND through the transfer case gives me a lot of combinations for testing. I can try any or all of them. It does not leave a lot of room in the maximum weight for a battery pack, but testing options may be worth the extra weight. I won't be undersizing the motor in any case.

I seem to have misplaced a couple of the clamps that hold the front drive shaft to the transfer case. There are no bolts and no clamps that I can see. Maybe I'll ask about those as well.

[thingstodo]

The total length of the drive train shown in the picture is 100 inches. The next 2 pictures show close ups of the measurements. The model of the electric motor ends about 2 inches further forward than the drive shaft. That is what the next 2 pictures try to show.

Measure from the rear U joint to the frame where the bearing is mounted - 42 inches. This matches the first picture. There was no way to take a picture of the measurement in the truck

Measure from the frame where the bearing is mounted to the front U joint - 61 - 62 inches. It's a bit hard to stretch the tape that distance when you are flat on your back beneath the truck, so a range of 1 inch is as good as it's going to get right now.

That mostly matches with the first picture which shows 100 inches, not 103 or 104. 3 or 4 inches for errors in measurement is still not great, but it's better than 25 inches was!

The motor - could not find a plate with information on it. Perhaps that plate is still on the truck somewhere. It is a 6 cylinder - that's all I have.

The transmission has more info. It has a large K stamped on one end, 21 on the other end, Hydromatic type 2TLM4 with the number 8676359 about the middle between K and 21. The serial number shows as 2 separate numbers, 4193 and 98626. The spline is about 5 inches long and there are 3 bolts from the flywheel to the torque converter (I think that's a torque converter). The motor side has 6 holes, on the reluctor ring/flywheel. But the torque converter has only 3.

[thingstodo]

The VIN is not on the dash. But it is on my old registration.
1GCDT19ZXM0161641

This web site VIN Decoder for cars, trucks and motorcycles @ Motoverse.com
tells me the following information about my truck:

1991 CHEVROLET S10
VIN:1GCDT19ZXM0161641
World region:North America
Manufactured in:USA
Year:1991
Make:Chevrolet
Model:S10
Body style:Club Cab Pickup
Drive type:4WD
Fuel type:Gas
Cylinders:6 Cylinders
Safety restraints:Active(Manual) Belts
Standard options:Power Brakes, AM Radio, ABS (2-Wheel)

Another site that breaks down each of the digits s10extremist.org
lists:
1GC = chevy, D = Brakes hydraulic 5001 - 6000 lbs, T = 4WD, 19 = - half ton, ext cab, Z = 4.3L V6, X = check digit, M = 91, 0 = Pontiac MI

So the two sites agree on everything with a few differences in the level of detail. The one that is a concern is the 2-wheel ABS. The insurance contact that I have tells me that any safety features that were on the original vehicle need to stay the same after conversion to electric drive.

From what I've read, the ABS did not work all that well to begin with. Making it work (rear only?) may be a hurdle. I won't worry too much about it until I get to it.

[thingstodo]

I was told by two different wreckers that the S10 for 91, in a 6 cylinder, was only available as a 4.3l. That matches the internet search I did so I'll accept that for now. I was looking for the maximum torque that the transmission can deal with - it is used by racing guys so the 4.3l engine is definitely NOT stressing the transmission. Depending on the source and some fine details about manufacture date and which vehicle the transmission came from, they seem to take at least 400 foot-lb of torque. I'm expecting less than 240 so there is no problem there.

Neither wrecker that I checked with had a 4x4 manual transmission for a 91 S10. One of them estimated that if he could locate one for me, it would be about $350. I asked about the length of the transmission, then had to explain that I was replacing an automatic. He said the supports would be in the wrong place for the manual. He remembered something about the support being movable, that the frame had holes for both positions but he did nit remember the lengths being different. He had not sold anything for a 91 4x4 S10 in a while, so he was not positive. The movable support is mentioned by a few people online who discuss S10 rebuilds but nothing specific to changing an automatic with a manual gearbox.

The net search mentions that the 4x4 gearbox has a shorter spline to give the transfer case some room, and since the transfer case has the longer spline for the movement on the suspension. Again, nothing specific like measurements. I did verify that the transmission is 26 inches.

The other thing I was searching for is the specs on the transfer case. Again, 400 foot pounds into the transmission with a 4.03:1 first gear puts over 1600 foot pounds out the driven end of the transmission. That's 2, 3 .. maybe 5 times what I can get. I don't think that I have to worry.

[thingstodo]

I managed to snag a lot of batteries, deep cycle batteries (3), an agm (1) and 3 starter batteries (720 - 850 CA) for a pretty good price. The one deep cycle, a Motormaster Nautilus, is not in the best shape - it is rated at 50 ah RC and started out at 12.07V. I charged it with a 6A charger for 12 hours and it had not 'finished'. It ended up at 12.93 after resting for an hour. The other deep cycles (Optima yellowtops) began as 13.06V and 13.08V. Those might have been removed from the shelf and surplused without being used. The AGM does not appear to be a brand name. It's RC is 190 and it began at 12.84V. I haven't gotten around to charging that one yet.

The two Optimas will likely run one DC/AC inverter each and I'll chain the high voltage DC (150V within the inverter) together to get 300 VDC. I need to test what current the Optimas will supply, and for how long.

The inverters will draw about 250A max for 30 - 60 seconds if the battery can supply that and stay over the cut-out voltage of 10.8 VDC. That would give me about 18A at 150 VDC output.

I have an older deep cycle that was on my boat - a Costco Kirkland deep cycle. I'll put that one in parallel with the Motormaster Nautilus and drive the larger DC to AC inverter with them (if I can get the inverter working - it was also surplus and last time I looked at it, the control board did not do anything. The transformers and transistors looked OK).

The larger inverter is rated for 5000W continuous, 10,000W surge. If I limit that to 250A in at 12V and get 18A out of it at 150VDC then the VFD can run on 450VDC. That's enough to do some low-speed testing on the 40 HP motor.

[thingstodo]

Why am I limiting things to 225 or 250A?

First, those kinds of large number scare me a bit.

Second, I got a REALLY good deal on electronic fuses that are rated at 300A so that leaves me a bit of room for safety before the (normally EXPENSIVE) fuses start to blow.

How do you take 18A at 450V and do low-speed tests on a motor that needs 37.3 amps and 575VAC?

The key is 'low-speed'. If you have 18A at 450VDC (about 320VAC), you can roughly use 450 VDC * 18A and get 8100 Volt-Amps or VA. Now that power (energy delivered per unit time) can be delivered by the VFD as a variable voltage at a maximum current. For example, I can use up to 36A at 225VDC, or 72A at 117VDC. I guess you can look at it as trading maximum voltage for higher current.

I'd like to deliver 37.3 amps or the motor's rated current. That should give me the motor's rated torque, or 120 foot-lbs. 8100 VA / 37.3 gives me 217 VDC or 153VAC - you divide the VDC by the square root of 2 to get the VAC. 153 VAC is just over 1/4 of the 575 VAC that the motor is rated for, so I should be able to get rated torque out of the motor up to about 25% speed, or just under 430 rpm. That test will prove out that I can get rated torque at rated current. This will be the first test of the 40 HP 575 VAC motor.

In another test, I'd like the motor to use 3 times rated current, or 3X for short, which is about 111.9A. Since that's 3 times the current I can only get 1/3 the voltage we discussed above (153) or just over 50 VAC. And the speed won't be very fast. 1770 rpm is rated speed. 575 / 50 = 11.5, so 1770 / 11.5 gives maybe 150 rpm or so. That test will prove out my theory that 3X current will give me around 220% torque or 264 foot-lbs.

In the last interesting test, I'd like the motor to use 3.5 times rated current, or 3.5X for short, which is about 130.5A. Working the numbers through, 8100 / 130.5 = 62VDC, or 44 VAC. 575 / 44 = 13. So 1770 / 13 = 135 rpm.

BUT - this is a practical limitation - since the motor 'normally' only needs 37.3 amps to generate 120 foot-lbs of torque, the 'resistance' of the motor (actually called impedance) will limit the amount of current that the motor can use ... this may be limited to 2X or perhaps a bit higher than that. In practice, the voltage may have to go higher to get higher current. So the last test may only get 100 rpm instead of 135 rpm.

The testing will show me how high the voltage needs to go to get 3X and 3.5X current, how much torque the motor will put out, and where it does not matter how much extra current you have - there is no more torque to give. I expect that the motor will heat up quite a bit during this test as well.

[thingstodo]

I guess I didn't sum up the testing part yet:

The maximum torque that I can wring out of this motor is VERY important in figuring out how good (or poor) the acceleration will be - golf cart (0 - 60 in 2 minutes) or similar to the old ICE (0 - 60 in about 20 seconds).

Crusing power needs to be measured too. How much torque do I need to cruise at 65 mph for half an hour at a time. The smaller the motor, the lower the maximum current and voltage need to be on the VFD, the smaller the maximums on the battery pack (or the boosters) need to be.

Until I find a transmission for SalvageS10, or come up with an easy way to connect the motor shaft to the transfer case (which is 20 - 26 inches away), I can't really work on the motor mount or get the truck moving under electric power.

I can work on the PLC program, or building the VFD, or boosting the battery power from 12V up to 150V to power the VFD.

[thingstodo]

I was contemplating the difficulty in getting a manual transmission for SalvageS10.

An idea .. hatched .. I was not planning on using the front drive shaft. I don't really need 4wd and it makes steering difficult if the truck is locked into 4wd all of the time. Instead of buying a transmission - could I repurpose the front drive shaft and instead connect it to the electric motor?

This may need a sketch ... but I'll attempt to explain without the sketch. Electric motor shaft to a new yoke that fits the front drive shaft, the drive shaft fits the transfer case as normal, but is driving the transfer case instead of being driven by it, the transfer case to rear drive shaft as usual, and the rear drive shaft to the rear differential, and on to the wheels.

How does that help? Well, if I can buy a new yoke (I think that's the name of the part) the same as the yoke on the front differential, then bore it out to fit onto the electric motor drive shaft (2.125 inches), I could mount the electric motor not-quite-straight in the engine bay, connected to the front drive shaft. The motor drives the front drive shaft, which goes to the transfer case, which connects the front and rear drive shafts, which transfers the power to the rear drive shaft ... and I can try my direct drive without paying someone to machine a coupler to go from the electric motor to the transfer case. The other option is putting in a manual gearbox and coupling the electric motor to the original position of the clutch.

So off I went to the local parts store where I was told that the transmission is bolted directly to the transfer case because the rear transmission bearing supports the transfer case. The spline that drives the transfer case also keeps the gears aligned and prevents the transfer case parts from moving too far forward or back.

Well, it was an interesting idea. Just another that didn't happen to work out.

This brings me back to the requirement for a manual gearbox. If the transmission supports the transfer case, then I need the transmission anyway. If it's going to be there taking up space and weighing so much, I guess it makes sense to have the electric motor couple to the transmission and use the selection of gearing that is provided.

Such are the ups and downs of my 'hobby'. That's how I'm describing SalvageS10 these days. I'm enjoying the learning experience and all of the 'gotchas' that are lurking around every twist and turn. You've got to enjoy the journey!

You may have noticed that no bearing in the transfer case means that I cannot go directly from the electric motor to the transfer case unless the electric motor bolts up to it directly to provide some support. The electric motor is too large (diameter) to do that without hanging really low beneath the truck. And I'm worried about the torque that I have right now accelerating the truck to a decent speed on direct drive already, so a smaller motor is not an option right now.