3 to 4-speed conversion

[Madmaxx]

new to the world of mopar..so beware!  lol..ok the car i have bought is a 72 340 3-speed barracuda...i'm hoping the conversion to a 4-speed wont be to tough??  educate me please....i have been told it was a 318 3-sp car originally..the car isnt here yet..but hopefully will be by then end of the week??? trying to layout a plan before tearing it apart!! thanks in advance!

[HP_Cuda]

I guess the major pain comes when purchasing the tranny, bellhousing, shifter mechanism, shifter, and clutch/brake pedal setup. Besides you need to add the zbar mount on the firewall which requires welding.

What is your budget?

[Killer_Mopar]

Sounds like you are coming from a 3-speed manual, if that is the case you I think you just need an 833 4-speed, shift rods, shifter pad, shifter mechanism, and the shifter.

[HP_Cuda]

I thought he was talking auto but yeah still the cost is in the tranny...

[Madmaxx]

yes 3-sp manual..sorry I should have made it clear..so the crossmember, clutch, yoke, and driveshaft all the same?..that would be great!!

[Chryco Psycho]

I have never done this , 3 spds are not common ! But you should be a at lot closer having a clutch pedal & linkage etc . I would go to a 10.95" clutch but the flywheel should be fine & I believe the spline is the same as the 833 , not sure on the belhousing & the 3 spd may use the smaller slip yolk but the driveshaft should work as well as the crossmember & floor tunnel  .

[Killer_Mopar]

My 383 R/T was originally a 3-speed and the bellhousing was drilled for both 3 and 4 speed patterns. The clutch was the same spline count and the crossmember wasnt an issue. But that was a big block so that might not carry over to a small block. However.......

My fathers 340 challenger was a 3-speed and I converted that one over to a 4speed a few years ago. Just had to use what I listed earlier. The bellhousing had both bolt patterns and the input shaft spline count was the same so the clutch was reusable. I am 90% sure the driveshaft was the same, but cant be 100% because I remember giving him my old 383 driveshaft, but I think that was because of a vibration issue and not fitment....

Good luck!

[Chryco Psycho]

sounds right , even the tunnel should be a perfect fit

[Madmaxx]

SWEEEETTT!! thanks guys!!!

[fantum]

Not having seen a 3-speed 'Cuda, I'm wondering if they made any column shift.  That will adversely impact the scope of the project.  Just thinkin........

[7071 challenger]

Make shure the transmission you will buy has a 23 splines input shaft. You have two choices: 18 or 23. Your 3 speed has a 23 plines input shaft, so, if you buy a 18 plines tranny, if won't fit in your clutch's disc. The good thing is, 23 splines are MUCH cheaper, as 18 plines are for 440-6 and Hemi. I think your drive shaft should be fine. Then, you need the shifter WITH the adapter plate, (you will have to get the adapter plate separately), rods and the shofter boot & trim ring.

Robert

[Killer_Mopar]

I think the 3 speed tunnel is not the same as a 4 speed tunnel so some cutting will have to be done.

The 3-speed AUTO tunnel is different, the 3-speed manual is the same as the 4-speed manual - no cutting needed.

[73restomod]

The driveshaft length may different, as well as the spline count of the output shaft. Getting a driveshaft cut and rebalanced is around 150 bucks. Mopar had 3 different spline counts, to know you'll count the output splines on the current trans and compare it to the new one to be sure. There are also 2 different lengths of slip yoke.

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