Upgrades and modifications on Seven

As I think back on my last blog, I hadn’t realized I had been quite so remiss in my own babbling way of relating new and used information to our followers. After meeting some of our followers at the Science Center in St. Louis last month, and having some of the other team members reminding me to get off my lazy fingers and start typing… here we are with a very long blog. Hmm, what to do? Where to start?

Why not start with what we’ve finished upgrading on Seven over the last year? The biggest changes where the addition of rubber mounts to the drive train, a new cooling system, custom A-arm bushings, and a new custom Quaffe differential for the transmission.

Seven’s always been very quiet and stealthy from the outside, except for the squeaky hub caps which we fixed last year with the addition of the new rims (the old rims were flexing and the hubcaps weren’t). From the inside, the motor whir vibrated at a harmonic throughout the space frame and the heads of the passengers; the faster we drove the louder it got. The solid mounts made for the XPRIZE race, for easy of manufacturing and efficiency reasons, were the perfect conduit for transmitting the high-pitched motor whir throughout the inside of the vehicle while keeping the outside quiet. So, very carefully, you know, with a Sawzall, we removed the old mounts one at a time, and sometimes modifying the frame as we went to accommodate the new mounts.

It was a simple design that would make a robust mount which would isolate the drivetrain from the vehicle frame: a cylindrical rubber tubing 1.5 inches in diameter pressed into a 1.34 inch steel tube, a steel sleeve in the center of the rubber for the bolt to go through, and some steel ears–two for mounting to the car’s frame and two for mounting to the drivetrain and voilà, you have a rubber isolation mount. Rinse and repeat with slight modifications due to issues with available room and six mounts later we done. With some careful planning and a little luck everything should be right back where it started and aligned, which it was (whew!). This style of mount is still really solid and rigid, not leaving much room for vibration. Because they are still fairly rigid, they will transmit motor noise into the frame, just at a lower frequency and energy than before, which is why a lot of electric vehicle converters will try to reuse the stock gas engine mounts already in a car; they are strong and not very rigid, making them nearly silent when used for a gas engine and reducing any noise to an imperceptible level when used for an electric motor. Our mounts, although not as quiet as stock vehicle mounts, worked quite well. Seven now transmits less than half of the audible noise into the passenger compartment than it once did. The whir that does still get transmitted is at a lower frequency making it much easier on the ears and pleasant to drive without losing any appreciable efficiency in the exchange.

The new cooling system is actually only half new. The temporary Fiero heater core that we’ve been using for four years was replaced with a slim transmission cooler and fan combo from Summit Racing and moved underneath the motor. The new position and new rubber drivetrain mounts required some mods to the original frame. It was time to clean that up a bit anyway. The two worked really well together and give us a much cleaner look under the hood. The peak temperature of any drivetrain component now is 145˚F, and that’s the inner CV joint on the driver side. The peak motor temp, which is the second hottest unit in the driveline after the CV, now tops out at 140˚F. Along with the new mounts and cooling system, we made a removable carbon fiber underbody panel to allow access to these units from under the car. Overall it worked out as we had hoped, keeping peak temperatures down and simplifying the motor compartment.

It’s kind of an odd story how we got to the point where we realized we needed new A-arm (or lower control arm) bushings. None of us had ever replaced them before on any other vehicle we’ve collectively owned, but now after the incredible results we’ve gotten, I’ll be considering it for all builds involving an older or custom vehicle from here-on-out.

Let me tell you about another upgrade we made this winter, a brand new Quaffe differential designed and built by our old friend and trans builder, John Frana of Frana Vehicles. This was an absolute beauty; a work of art in metal and oil. We have a very small Geo Metro gear box hooked to our trans that John has slowly replaced all the inners with until we reached the point where only thing Metro about it is the size and casing. We’re very pleased with all the upgrades; They just work like a trans is supposed to. However, every once in a while with untested custom parts, you run into a piece of material that has a flaw, a micro crack, something that didn’t heat treat quite right, a contaminant in the steel or an angle that might be off by 0.0001 of an inch, none of these possible trouble spots are identifiable until you put the part to the test. Then it either breaks or it doesn’t…and one of our new gears in the differential had a flaw, not a manufacturing error.

Let me tell you the story as it presented itself to us. We had just finished the winter upgrades and had been taking Seven out for some leisurely break-in miles. No reason to hurry as we had no scheduled events to attend. Dad drove the car for awhile, I tooled around in it some and then Josh brought friends out to give them a ride. Josh had been apprehensive about the old trans breaking on him and waited until we had the new parts in before chauffeuring a test ride. So Josh loads up the car with some of his buds from the Petersburg Terror in the Field Haunted Experience. With only 95 miles on Seven since the winter build, Josh goes to turn the vehicle back towards home, EV grins on everyone’s faces, and the steering wheel wont turn…this is odd. Then there’s a “POP” and the wheel now turns freely. Josh completes his turn and heads back to IMW headquarters (aka “the shop”). Back at IMW HQ, the steering wheel locks up again and frees itself with another loud “POP!” I can hear from inside the shop when he turns into the drive. Josh relays the story to me once Seven is parked and he’s concerned about what happened. We talk about it for a few minutes and remember something similar happening when a mounting bearing came loose on the rear steering linkage back when Seven was still just a frame. We figured that must be it: the bearing came loose which allows the U joint to become unaligned and then gets ‘locked’ into position, making a loud “POP” once it gets passed the ‘locked’ up or bound up position. No worries, I figured I’d crawl under the car the next day to straighten it and tighten the bearing mount.

The next day I squeezed my way under Seven and drilled out the rivets that hold the rear steering and wiring channel inspection cover for the rear steering, pulled back the cover and exposed the steering linkage. I inspected and lubed the linkage and asked Jen to help assist with turning the steering wheel while I was under the car trying to see what’s going on. It didn’t stick or pop on us; the only irregular movement it made seemed to be a slight shimmy in the steering rack mounts themselves. I continued checking out the steering, working from where we thought the problem was outward toward the wheels. When I got to the driver side wheel, I needed to jack the car up in order to inspect the steering components in action. Other than a slight movement in the inner tie rod end, which we’ll replace this coming winter build season, I didn’t notice anything and I started to think an outer or inner CV joint has gone bad and is binding under certain conditions. That’s when I saw something odd. Jen turned the steering wheel again, very patiently I might add (turning a wheel back and forth and back and forth and back and forth is quite tedious when it seems like the guy asking you to do this has no idea what he’s looking for). I saw something in addition to our locking steering noise. I noticed that when the steering reached the end of its travel the tie rod stopped for a second, but once a little more pressure was added to the steering wheel it continued its inward journey, pulling the A-arm in with it until the rear a-arm bushing was completely compressed and steel is touching steel. Not good. NOT GOOD at all!

No wonder it’s been so hard to do an alignment on the car; the bushings are shot. Part of that was our fault because of the way we’ve been strapping the car down onto the trailer when we take it places. Part of it was the old bushings, and part was the original design of the bushings. I found out later from John Frana that the only vehicle that he’s ever made custom bushings for is the Dodge Neon because they are notoriously soft. So I asked if he would make us some, too, and WOW what a difference! The car not only drives better and straighter, but its ride has been improved and quieted (which is odd since the new bearings are actual ball bearings in an aluminum sleeve and not rubber at all. They should be louder). Seven also used to make a spring slapping sound when going over big bumps. We’ve heard this before on lots of old cars, the thing is it doesn’t make that sound anymore.

But wait Kevin, what about the steering and popping noise that led you to this discovery? What was that? I’m getting to it…that’s another thing we thought we knew we didn’t really know. As it turns out, one of the new gears in the differential had a flaw in it. We had one flawed gear; the others didn’t break under load. A tooth came off a single planetary gear on the driver’s side of the differential. The broken tooth lodged in the differential but didn’t make any noise or prevent us from driving because the internal gears on the differential only spin when the front wheels are moving at different speeds, i.e. when you’re turning. With the differential lock, our front tires would not longer move at different speeds. This is no problem down a straight country road but a really big problem when coming to a turn. The power steering unit we added to Seven puts out about 1/3 hp max and the drive motor puts out 200 hp max, so you have a 1/3 hp motor fighting against 200 hp to turn the wheels. That’s not going to happen and the steering appears locked in place. If you put enough pressure on the steering, the broken tooth in the differential “POPS” loose and you can steer again.

Our beautiful new differential had broken. I had to tell John Frana the bad news and ask about A-Arm bushings.

John built us some A-arms bushings and made some replacement gears, which we’ll be putting in again during this upcoming winter build.

Other items we’ve added/improved since I last updated the site:

  1. Modifying the side mirrors so they are permanently affixed in place. No longer do they hinge up and down – which was never a design meant for gull wing doors that open up and jar the mirror out of place with every iteration.
  2. Adding a hood release to the inside of the car so we no longer have to pop the hood ‘Chicago Style’ with a screw driver.

Although we looked into mounting our regenerative shock this last winter, we ran into room constraints that would have required us to modify the frame. To do that we would have to pull out the drivetrain we just installed. That experiment will happen this winter. don’t worry, I’m just as excited (ok, probably more exited) than you are to find out how that works. I let you know the results…eventually.

One Response

  1. Hope the mounting of the regenerative shock this winter goes well. Very curious about real world experience, and numbers, from it ever since I learned about it through EVTV.
    Really admire what IMW has done and continuous to do.

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