72 Chevelle manual transmission hump - Chevelle Tech
Transmission & Driveline Transmissions and Differentials

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  • 1 Post By RHinkel764
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post #1 of 8 (permalink) Old May 17th, 19, 11:20 AM Thread Starter
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72 Chevelle manual transmission hump

I have a 1972 Chevelle SS clone

I am converting from automatic to 4 speed

My question is this:

Does anyone know the dimensions from front to back on mounting the manual trans hump

Does any one have experience in this

I know I can set the trans in the car with the shifter and measure where the hump will go

Unfortunately I am not at this stage

Chevy must of had a standard for welding these humps in?
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post #2 of 8 (permalink) Old May 17th, 19, 5:51 PM
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Re: 72 Chevelle manual transmission hump

The hole in the floor was cut with a Blue Wrench. A template was laid on the floor and then you light the blue wrench. I have a piece of floor from a 70 that had a 4 speed " Bench seat " hump.
If I can help , Let me know. Console cars had a different hump, I believe?

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post #3 of 8 (permalink) Old May 17th, 19, 6:39 PM
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Re: 72 Chevelle manual transmission hump

Agree they weren't done from the factory cleanly. The reproduction hump that is available actually fits the floor pretty well. Just lay it on the floor in its position, trace the outside and then cut your hole leaving enough material to attach it to.

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post #4 of 8 (permalink) Old May 18th, 19, 8:08 AM
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Re: 72 Chevelle manual transmission hump

Yes there are two different humps depending if one wants to have a console or non console. Once you acquire the transmission you can pretty much calculate where the hole for the hump needs to be via a tape measure.
I helped a friend do a conversion on a Nova and IIRC we just waited till the trans was installed, without the shifter attached. Then from the bottom drilled a couple holes in the trans tunnel that were centered over the shifter mount area on the trans. Then just went on top and set the hump over the drilled holes and drew a line around the hump with a magic marker. Finally cutting out the hole for the hump just making sure to stay within the magic marker line on the trans tunnel.
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post #5 of 8 (permalink) Old May 18th, 19, 10:04 AM
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Re: 72 Chevelle manual transmission hump

I completed my conversion a few months back. I posted a long thread of thank yous and pics of the project including the hump. If I had to do it again, I would cut the hole as recommended above. Just lay the new hump on your floor. Itll only fit in one area, trace it and cut it out an inch or two smaller than the outside diameter so you can attach the hump to the floor. I cut the hole wanting to keep the original piece just in case. So I drilled a hole big enough to get a skill saw blade in, then I cut using a metal cutting blade. I had it out in minutes and the cut was perfect. You should see the factory cuts.... Frankenstein-ish.

I attached using rivets as Im not a skilled welder and it held great. Things I would do different would be Id instal the trans then place the hump and secure it after lowering the trans slightly. I was off center slightly. Also for a nicer finish, I would get a heavy body hammer and a dolly and beat the two edges close to one another so I wouldnt have to use so much seam sealer. Last if you have a console, you can now figure out where to place the rear mount once this is all in by dry fitting the console. Heres the link for my progress:

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post #6 of 8 (permalink) Old May 18th, 19, 10:20 AM
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Re: 72 Chevelle manual transmission hump

Remember the part about the console, as it is important in determining which of two different humps you should select. When I did a changeover to a '65 Malibu many years ago I simple set the hump over the existing floor, chalk marked the floor around the hump, moved in about 1" for welding material, marked/cut the floor out. I then drilled a whole bunch of holes in the hump, lightly dressed the 1" perimeter around the hole in the floor and plug welded the hump to the floor. I then dressed the welds and used sealer around the perimeter of the hump.

When placing the hump, it will normally be self-explanatory where it should go, as it should all but 'fit' itself.
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post #7 of 8 (permalink) Old May 18th, 19, 12:17 PM
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When I converted mine, I cut a rough hole just to install/locate the shifter. There’s lots of room after it’s installed to make the final cuts. And install the hump. I plug welded mine in place.

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post #8 of 8 (permalink) Old May 19th, 19, 2:06 PM
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Re: 72 Chevelle manual transmission hump

The aftermarket stamped hump piece has a definite spot where its happiest. But, what trans do you have now and whats going in? I had a PG and swapped to a muncie, which happens to be the same length. Installed the shifter on the muncie, measured from bellhousing back to shifter, then measured the PG in the car and made a mark. I also put tape on the garage floor about where that was, then laid the hump panel in the car and stood back to look and see. It lined up perfect this way.

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