Best floor hump for 4-speed conversion

[Sly]

Where to find the best floor hump part for a 4-speed conversion ? (Passon four speed trans, McLeod clutch, Kesler bellhousing)
It is for my 71 - 383 Challenger.

Thank you.

[anlauto]

AMD is the best quality

[Cuda Cody]

   AMD seems to have the best reputation. 

[Blake@diyhemi.com]

I used AMD and the shifter sits dead center of the opening

[cataclysm80]

In years past, I recall that the 4 speed humps were designed to fit 1971 and up floor pans, and the contour of a 1970 floor didn't quite match, leaving a gap in one spot.

Is that still an issue?

[Blake@diyhemi.com]

In years past, I recall that the 4 speed humps were designed to fit 1971 and up floor pans, and the contour of a 1970 floor didn't quite match, leaving a gap in one spot.

Is that still an issue?

Not that I recall. My car is a 70 and it fit perfectly all around.


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[Sly]

Thank you guys ! 

[Blake@diyhemi.com]

The real differences in floor pans over the years are the dimples where feet go and the torsion bar humps on the passenger side. Not much else differs from what I've seen. I'll let more knowledgeable people chime in, however.

You should be good to go

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[cataclysm80]

The biggest difference in floor pans is the way they attach to the inner rocker panel.

The 71-74 inner rocker panel has a ledge that the floor pan sits on and welds to.
These floor pans are just flat at the sides. 

Here's a cross section of this later style, that illustrates pretty well how it works.
I've circled the ledge with the floor pan sitting on it.

[cataclysm80]

1970 does not have that ledge on the inner rocker for the floor pan to sit on.
The 1970 floor pans have additional metal down each side, and that metal is bent upward to form a vertical flange which is welded to the flat inner rocker.

Before AMD started making their 1970 style floor pans, all of the reproduction floor pans available didn't have the additional material down the side, which was required for welding the pan to the inner rocker.
More than a few people removed their entire original 1970 floor, only to discover that their replacement floor didn't have any way to fasten to the inner rocker.  Then they had to get creative and fabricate a solution.
If you were aware of the issue, or just really paying attention, then instead of removing the original 1970 floor at it's spotwelds, you would cut it a little ways inside the perimeter, leaving a strip of the original floor as the ledge which was needed to attach the later style floor pan.

Here's a pic of a 1970 floor which has had a section cut out for repair.  Have a look at the inner rocker, no ledge to sit the floor pan on.

Second pic is of a rusty 1971 and later style floor pan, sitting in a 1970 car to show the difference.  You can see that the later style floor pan is just flat at the edge, but the 1970 car has a lip bent up at the edge of it's floor pan, which is how it's welded to the rocker.

Third pic is of the AMD reproduction floor pans.  It's a little difficult to see, but the edge is different.

[cataclysm80]

That was the first change that happened with floor pans.
The 1970 floor pan fastens differently down the side.
The 1971 to 1974 floor pan is the same part that was used on the newly redesigned B bodies.


Later in 1971, there were additional changes in the contour of the floor.  It was several small changes that don't affect function, but are noticeable if you know what to look for.  I'm not sure when the change happened, but it's not difficult to find examples of both floor styles in 1971 cars.

I've circled some of the changes in this picture of a 1971 Challenger.

The second picture is a comparison without the red circles, so that you can get a better look.
I'm unsure of the Scheduled Production Date on the 1971 car, but the 1970 car was built in June of 1970.

The third picture is a better look at the differences in the ribs of the foot well.
Interestingly, the blue car in this picture with the earlier style of 1971 floor, is actually a 1972 car with a Scheduled Production Date of July 30th 1971. 

[cataclysm80]

It's great that AMD offers floor pans with 1970 edges and also the later style edges.

However, the middle section on both AMD floor pans is the same.
Most of the contours are like the 1970 style, but the ribs in the foot well are the later style which first showed up in 71, and was used on the vast majority of 72-74 cars.

In other words, the AMD floor pans are not exactly like anything offered from the factory.
For most people, this doesn't really matter, but if you're going for OE Gold, you might want to pay attention.

[cataclysm80]

OK, so back to the topic of manual transmission floor humps.

It looks like the AMD floor humps are made to fit all AMD floor pans, and 1970 (and some 1971) cars.

Here is a picture that I saved back in 2009, of a different manufacturers floor hump.
I'm not sure what company offered this particular part, but it's made to fit the later 71 style and afterward floors.
Back then, floor patch panels were also that late style.

The gap caused by the different floor shape is marked in red.

[Blake@diyhemi.com]

That was the first change that happened with floor pans.
The 1970 floor pan fastens differently down the side.
The 1971 to 1974 floor pan is the same part that was used on the newly redesigned B bodies.


Later in 1971, there were additional changes in the contour of the floor.  It was several small changes that don't affect function, but are noticeable if you know what to look for.  I'm not sure when the change happened, but it's not difficult to find examples of both floor styles in 1971 cars.

I've circled some of the changes in this picture of a 1971 Challenger.

The second picture is a comparison without the red circles, so that you can get a better look.
I'm unsure of the Scheduled Production Date on the 1971 car, but the 1970 car was built in June of 1970.

The third picture is a better look at the differences in the ribs of the foot well.
Interestingly, the blue car in this picture with the earlier style of 1971 floor, is actually a 1972 car with a Scheduled Production Date of July 30th 1971.

The floor ribs are exactly what I noticed when I replaced that metal in my car. I left feedback for the company saying they fit great but not OE correct just for their information and they blocked me from ever buying from them again, lol!


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[cataclysm80]

Just thought I'd also add that while the front floor pans are the same for both Barracuda & Challenger,  the rear floor pans are different on Barracuda vs. Challenger. The Challenger has a two inch longer wheelbase. On the bottom of the car, the Challengers extra two inches are a flat strip of metal which is at the leading edge of the rear floor pan. Challengers also have an extra body plug on each side of the car within that 2 inch flat section.

To put Challenger rear floor pans in a Barracuda, you'd need to cut two inches off.

To put Barracuda rear floor pans in a Challenger, you'd have to weld in an extra two inches across the front.


(just a note: On the side of a Challenger the extra two inches are between the rear wheelwell & the door. On the top of a Challenger the extra two inches are mostly in the C pillar, but the whole roof is different, so it's hard to compare.)

I've sort of marked the extra 2 inches here in the Challenger picture.