Fiero Gantry (for dropping the cradle)

[pmbrunelle]

I built this a few years ago, but maybe not everyone knows about it, so I thought I would share.

The initial requirements:
Easy/cheap to build (wood, with PL Premium and woodscrew construction)
Safe enough to go underneath the car
Can be taken apart for more compact storage

Here's what I came up with.

The main horizontal beam (ignore the aluminium ladder):

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Two A-frames, and a pair of 2x8s with plywood end gussets:

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The setup assembled in the backyard:

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The main beam is suspended from 1/2-13 threaded rods, which are attached to the top of the A-frames. You turn the nuts on which the beam rests to raise/lower the rear end of the Fiero. We can see how the A-frames are held upright with the 2x8s. The idea is that the 2x8s are stiff/strong in bending, but they are flexible in torsion, allowing the A-frames to sit flat on uneven ground.

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The non-permanent joints are bolted together with 1/4-20 bolts:

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These discs are inserted through the strut towers (struts must be removed first). The beam is lowered to the strut towers, the discs are hooked up, and then the beam can be used to lift the rear of the car.

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Last summer I was running 175 kPa MAP, and then the clutch started slipping, so I've been running off of wastegate pressure since (160 kPa MAP). Soon I will be finally changing the clutch on the Fiero; the right combination of time/space hasn't come up until now.

[eHoward]

Good stuff! Thanks for sharing.

[Honest Don]

I’d trust it.

[The Dark Side of Will]

Looks hella more solid than things I've seen used to lift cars on Old Europe.

The "strutt plugs" area great touch!

[ericjon262]

looks tough, I wouldn't be too concerned about using it. how long does it take to lift a car though? I would imagine tightening those screws could get tedious after a while. on my A frame, I used a chain fall (which has it's own issues), but is relatively fast to use.

[pmbrunelle]

Yeah, I feel safe with the setup, though I wouldn't characterize it as overbuilt. Considering the safety implications, I had my dad review my plans before building the gantry, just in case I missed something. He didn't notice anything wrong.

It can be a bit tedious to raise/lower the car. I would say that by myself, an up/down movement would take me an hour, going back and forth (between both sides) in a relaxed manner. With a helper manning the opposite nut, it's a bunch faster. For a project car I don't mind... an hour or two of lifting isn't a big deal when the car is down for a month or longer.

One nice thing about the wrench+nut setup is that the fine adjustability; it's easy to get the body aligned precisely relative to the cradle bushings, so the bolts can be pushed in easily by hand.

I have raised the rear of a Fiero about 15 times now (maybe 10 times for fitment checks during turbo fabrication), and I noticed wear on the nuts, so this time I will be replacing them. The threaded rods aren't noticeably worn. I was using gear oil to lubricate the threads.

My dad recently gave me some thrust bearings, so I will be trying a thrust bearing on one side, and a plain washer on the other side. This will allow us to compare the turning effort with/without the thrust bearing.

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[The Dark Side of Will]

Use graphite anti-seize on the threads... Even once the oil squeezes out, there's still a coating of graphite in the interface.

[pmbrunelle]

Well, the thrust bearing was a total fail:

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I suspect that crud from the screw got wedged into the rollers. Probably if I wanted bearings there, I would need a fancier more sealed solution. For now, the plain washer will suffice.

[ericjon262]

I'm not terribly surprised by the result, those bearings are so tiny. it was definitely worth the try though.

[pmbrunelle]

They had 3000 lb ratings

Fresh off the camera:

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On the setup as described, I think that the horizontal beam would interfere with the flying buttresses on a fastback Fiero. However, it should work with short lengths of chain to raise the height of the beam relative to the strut towers.

[ericjon262]

They had 3000 lb ratings

I assume you were using precision ground washers on both sides?

I bet it feels good to be making progress on the car!

[pmbrunelle]

Yes, I was using the washers that were included with the bearings (see photo with the parts laid out).

I'm not sure if I'll get to the dragstrip this year; once the clutch is installed, I'm supposed to drive around calmly for a while to break in the clutch, before doing any dragstrip launches.

However, if the car is generally ready for the dragstrip, but the clutch isn't broken-in yet, I might just launch off-idle (like a normal 1000 RPM street start), and then see what trap speed I get. I can try for a good ET another time.