Another Modification To The Engine Hoist.

sanddan

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I am in the middle of doing a new clutch for my corvette and had to make a fixture to help with removing the rear suspension cradle. A clutch change involves removing the complete drivetrain from the engine on back. I borrowed a fixture from a friend that mounts on the engine hoist that supports the transmission/rear end assembly but it wouldn't work until the rear subframe was removed. To make it easier to align things during the reassembly process I decided that the subframe fixture should include a parallel link system so the fixture stays vertical when raised and lowered. I modeled the basic engine hoist frame to make it easier to design the linkage. The new parts are shown in red.

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First step was to drill the 2 pivot holes. The hole in the main support member was hand drilled.

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The other was drilled using the mill.

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The lower hole is original, used for attaching the chain, the two upper holes are for the 2 different fixtures.
Most of this will be built using materials left over from other jobs but I did have to buy some flat bar. First step is to cut two pieces to length that will be the lower links.

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Setup for drilling the 4 pivot holes. No close tolerances required so a simple stop was used.

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I needed 4 spacers so I found a piece of an old barbell to use for raw material. Just a drilled hole and parted to length.

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Nothing fancy required.
 
clutch21.JPG clutch17.JPG Next was to make the stem that forms the last part of the linkage. The support structure will be mounted to this piece.

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Crappy weld, I used Tig and didn't grind off the mill scale. Ok for this project but I did go over it later with the mig welder. The jack came in handy to prevent the tabs from pulling in when welded.

The basic linkage assembled to the engine hoist. Checking the fit.

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The rest of the design was done on the fly. I wanted to support the rear subframe and keep the weight balanced, also wanted to key the fixture to the subframe if possible so things wouldn't be able to shift around. The first piece is tacked together to check fit.

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Add more tubes for the second support.

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Time to check fit again. This process was done several times as the structure gets fleshed out.

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So far the support piece has just been clamped in place as things have progressed. I decided to make this piece bolt on so it would knock down into smaller pieces for storage. It also allowed me to make it adjustable and I can use the basic linkage with a different fixture bolted on if needed later.

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In action. It worked perfect, easy to align and lowered straight down without drama. I used 2 ratchet straps to clamp the subframe to the fixture.

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A day well spent, now back to the clutch job. clutch13.JPG
 
Another mod was required. The hyd slave cylinder the releases the clutch has a remote bleed line installed. The new slave wasn't finished where the bleed line was mounted so I milled the rough surface flat so the copper crush washer has a good seating surface. I also had to tweak the adapter fitting a bit. Sure is nice to have the right tools for the job.

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That's a great way to extend the use of the shop crane. I will have to keep those ideas stored away in case I need them
Thanks for sharing!

Also, you did a great job of photographing the build and showing it in use...I often get to caught-up in the job to bother with good documentation.
Plus I hate having my cell-phone (camera) in the shop, too much dust and sparky/heavy things.....

-brino
 
Thanks brino, wasn't sure how this would be received on this site as there isn't a lot of machining. I have an older shop camera that I use so I don't mess up the phone. Many of the pictures I'm taking on this job are going to help me put the car back together. I'm over 125 pics so far and still wish I'd taken a few more LOL.

I did this as I am too cheap to buy a high lift transmission jack for what I hope to be a one time job. The cheapest jack I found was over $200 and I am only into this about $30 in steel that I can always salvage if needed and a day of my extremely cheap time (retired). I am doing the clutch job by myself so I need all the help I can get. The local shop wanted to charge $1800 in labor alone as it is a major job getting to the clutch on a corvette. If I didn't have a lift I never would have attempted it, I'm too old to crawl around on the cold concrete.
 
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Please correct me if I'm wrong. It looks like the corvette rear end/weight is extended out past the hoist wheels. Possible tip over. I've made a couple of mods on my hoist and made sure the supported weight is inside the 4 wheels on the floor. That is a really good modification.
 
Please correct me if I'm wrong. It looks like the corvette rear end/weight is extended out past the hoist wheels. Possible tip over. I've made a couple of mods on my hoist and made sure the supported weight is inside the 4 wheels on the floor. That is a really good modification.

Well Tom, I wouldn't lift my lathe like that! The weight is small enough that it wasn't an issue in this case but you are right, the CG should be within the wheel base at a minimum to ensure it's stable. I moved the hoist as shown in the pics to the next bay over and never felt any "twitchiness". Lifting very heavy loads at or near the rated limit with the wheels within a foot of the lift point will make the opposite end of this hoist "light feeling". That's typically time to reset the legs if possible. I also spread out the main legs to provide a more stable base which helps a lot when moving a heavy load.
 
Great Job!!!
i like your out of the box thinking!
I agree it always good to have the right tool.
it's also good to have the ability to make the right tool, when you don't have it!
 
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