4-Speed Conversion

[troutstreamnm]

Hi All and Happy New Year 

I'm doing a 4-speed conversion on my 71 Challenger big block and need to confirm how much floor needs to be cut away to allow clearance for the shifter and linkage.  I have already cut a square behind the frame support for the shifter mechanism to penetrate the floor.  This lines up with the hole in the 4-spd hump.  Do I need to cut any of the floor out in front of the frame cross member to accomodate linkage clearance?  Thanks for any help 

[Chryco Psycho]

Ys you do , do you have the tunnel to weld into the car yet ?
What I do is basically trace the outside of the new tunnel onto the floor & cut approx 1" inside that all the way around , the shift rods will pass above the tranny crossmember to get to the trans so it needs to be cut down to 6" or so back from the gas pedal 

[troutstreamnm]

Thanks again Chryco for your help    I do have the new tunnel so I will go ahead and cut the rest of the floor out as indicated.  I used the 1" method to mark and cut the area I did remove.  Do you recommend to wait to weld the tunnel until after the tranny is installed?  The tunnel fit seems clear, but my 6th-sense tells me to wait.

Thanks,

Trout

[Chryco Psycho]

I weld the tunnel last , it is easier to install & set up the linkages etc with the tunnel out

[Stacked440]

I did the same on my challenger, it was tacked in by the previous owner of the car and it was NOT in the right place at all and he didnt bother to cut much out from underneath it, so i cut it back out with a cutoff wheel and traced it with a marker cut it out 1" just like c.p. recommended above.  Looks fantastic, almost can't tell it wasnt factory.

[71chmark]

here's mine

[Stacked440]

Also I don't know if it mattered at all but I bent a piece of steel and tacked it in to go over that cross-member underneath the tunnel to keep crap from getting in there

[GoodysGotaCuda]

wow i didnt know that much needed to be chopped off. If you could please keep us updated with the swap, I'm gathering parts for one and it sure would be helpful to have a few pictures and things to go by when its time to do mine...if you dont mind. 

-Mike 

[sleepychallenger]

  it would greatly be appreciated if you take lots of photos. I will be doing the same thing within the next year or so, unless someone who has done one wants to come here and help me do mine.   

[GoodysGotaCuda]

  it would greatly be appreciated if you take lots of photos. I will be doing the same thing within the next year or so, unless someone who has done one wants to come here and help me do mine.   

  its hard to find good mopar write-ups. i've tried to do a couple small ones myself, headlights on relays, latemodel alt upgrades...but nothing quite like a 4speed swap. It would be beneficial to many! 

[Chryco Psycho]

I gues I should have documented 1 of the 3 I did last year 

[chevyconvert]

my hump was riveted in and sealed by the previous owner

any potential problems with this 

[Chryco Psycho]

I would seal it from under the car other than that no prob

[GoodysGotaCuda]

I would seal it from under the car other than that no prob

Thats what i plan to do, Rivets should be just fine. 

[73EStroker]

Rivets are ok but welding gives some X-torsional strength to your car believe it or not. Remember some guys weld all of the seams in their car when they upgrade to lots of HP.