New Owner, Transmission swap

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DusterFrank

DusterFrank

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Hello,
I recently picked up a 70 340 auto console. Really like this car except for the automatic transmission. I am seriously considering doing an auto to manual upgrade but I see a lot of different information on doing this throughout the web.
The choices I am considering are,
-Tremec 5 speed
-Tremec 5 speed with hydraulic upgrade
-Passon hemi overdrive
-Brewers 4 speed conversion (believe they're out of stock)
I have a quote from Silver Sport for the Tremec but the rep said that it does not come with pedals, z bar and linkages as well as the fork pivot. The rep did not know exactly what was needed additionally but suggested that I contact Brewers.
I've also heard that if I go with the non hydraulic upgrade, I would need to weld the pivot ball for the z bar to the frame and modify the tunnel.
This is a project I am planning on doing over the winter months but I do not want to do a project that is out of my scope. I've replaced engines, transmissions and clutches in the past but have not tackled a job that seems like a major undertaking and screwing something up in my car.
Any insight is appreciated. Thanks!!

Duster 1.jpg
 
Perhaps consider a manual shift auto.
Mine started new as a 4 speed, got tired of changing syncros, (racing), went manual shift auto, - less breakage, more hardware, almost as much fun as a 4 gears when combined with line-lock.
Back to 4 speed now, and just broke my left foot, chit ! lol

Very Nice car ! !
 
No matter which trans you decide to go with, you will need to at a minimum need to cut the floor/trans tunnel to install a four speed or the Passon overdrive- there are reproductions of the factory four speed "humps" that then get welded in place. Brewer's, AMD and others carry them. The rest- pedals and linkage- pretty much bolts in, most of the bracket and pivot locations are already present, you just need to come up with all the bits and pieces. "Welding in" the pivot must be referring to a couple of tack welds to hold the pivot reinforcement plate in position; the pivot itself does not normally get welded.
The Tremecs, however, require a substantial amount of surgery to the floor pan as well as removal and reconstruction of the transmission crossmember center section; and since this is a structural member and anchor point for the rear of the torsion bars it cannot be skimped on. If you're not comfortable with that level of modification, stick with the four speeds (comparatively minor mods as compared to the Tremecs) or as @Inertia suggested have your automatic modified to full manual operation.
 
Silver Sport reproduces the correct factory appearing A Body pedals in house. So not sure why they are telling you they don't have them? All the Silver Sport kits come with hydraulic clutch which requires less leg effort then mechanical clutch linkage
 
Professor Fate said:
No matter which trans you decide to go with, you will need to at a minimum need to cut the floor/trans tunnel to install a four speed or the Passon overdrive- there are reproductions of the factory four speed "humps" that then get welded in place. Brewer's, AMD and others carry them. The rest- pedals and linkage- pretty much bolts in, most of the bracket and pivot locations are already present, you just need to come up with all the bits and pieces. "Welding in" the pivot must be referring to a couple of tack welds to hold the pivot reinforcement plate in position; the pivot itself does not normally get welded.
The Tremecs, however, require a substantial amount of surgery to the floor pan as well as removal and reconstruction of the transmission crossmember center section; and since this is a structural member and anchor point for the rear of the torsion bars it cannot be skimped on. If you're not comfortable with that level of modification, stick with the four speeds (comparatively minor mods as compared to the Tremecs) or as @Inertia suggested have your automatic modified to full manual operation.
Click to expand...
This is the pivot ball I was told that needed to be welded in. I think I am going to go with the four speed conversion and also look into modifying my auto. Thanks
1726435985154.png
 
340sFastback said:
Silver Sport reproduces the correct factory appearing A Body pedals in house. So not sure why they are telling you they don't have them? All the Silver Sport kits come with hydraulic clutch which requires less leg effort then mechanical clutch linkage
Click to expand...
I was told by their rep that they do not supply the pedals.
 
DusterFrank said:
This is the pivot ball I was told that needed to be welded in. I think I am going to go with the four speed conversion and also look into modifying my auto. Thanks
View attachment 1716303740
Click to expand...
That's a replacement ball stud if the one in your bellhousing bracket is worn out, you grind the old one off and weld the new one in.
1726436348192.png
1726436589441.png

The body side ball stud gets bolted through this reinforcement plate, which is normally tack welded to the back side of a lower section of the inner fender well.
1726436560750.png
1726436644467.png
 
DusterFrank said:
Here is a screen capture of what was sent to me. I don't see any mention of pedals.View attachment 1716303778:
Click to expand...
Nor do I see any mention of clutch linkage (hydraulic or mechanical), bellhousing or bellhousing adapter plate, or output shaft slip yoke.
That is a base installation package.
(Per their site) you also may need:
1726446422866.png
 
Four gears are nice,
five are better.
8 are too many.
4+1, and splitting gears is the bees knees.

For street use,

with a MOPAR, manual trans, you basically have a 2-gear car, cuz in most cases Second will top out somewhere between
60@ 5100 with 3.55s, to
60@ 5600 with 3.91s, to
60@ 6170 with 4.30s..
But your cruising comfort take the hit with each rear gear increase.

My combo gets me to;
60@ 5100 in Second or
60@ 6400 in First-over with a 3.09 first gear, or to
(60@ 5500 in First-over with a 2.66 first gear) AND
Gear-splitting takes me to 93mph =6160 in Second-over; with
Splits of .78-.80-.78 ...... And
Cruising with 3.55s, goes 65= 2240, which makes me very happy.

My current combo is
Commando A833/GVod/3.55s
Having arrived there by trying every Mopar A833, and nearly every rear gear from 2.76s to 4.88s
I can confidently say that the best combo to use is the one that puts Second gear where you need it to be and toheck with what the other gears are doing, cuz on the street, about 95% of the time, you are gonna be in Second, and if your 340 can't pull it decently, you are gonna get frustrated. AND
Just as importantly, if Second gear tops out at 60=5100, then do not cam it for 60=6160, cuz she'll be over 1000 rpm off the cam!
PM me for more information.
 
Super nice car, and in my opinion, for what it's worth, it would be a shame to change it. If you want to shift the transmission all the time, fine, either look at a manual valve body from COPE or somebody, or install a Transgo TF-3 shift kit. But, in the end, it is your car to do with as you see fit and your wallet can handle. If I still (wishful thinking), the automatic would still be in it. Here it is in all it's glory about 2 months old.

1971 Duster (2).jpg
 
I’m doing a manual swap in my 68 dart. The TKX would of been nice but the $6500 quote was a touch pill to swallow.. I managed to score a freshly rebuilt 833 4spd setup out of a 71 swinger that the owner wanted to swap to an auto.. I bought the odds and ends from brewers that I was lacking like pedals, floor hump and various hardware. I won’t be doing much interstate trips in it so I can live without the OD plus, I kinda wanted to OE with a lot of stuff.. keeps the guess work factor low. Now this swap still wasn’t what I would call cheap but a couple of grand cheaper than the TKX swap. That $6500 quote did include it all including the driveshaft that would arrive later after you measure for it. It always ends up being more than planned I swear lol

If an OD is a must, lots of people out there has used the T56 among other choices.. just need to be willing to fab a bit more to make it work. malwood makes a hydro kit that just adds the clutch pedal itself to your existing pedal assembly after ya cut down the brake pedal pad down to size.

Lots of possible routes to take.. in the end I’ll be glad I’ll give mine the 3 pedal solution despite the cost.
 
Like I said earlier, on the street, our cars are 2 gears to 60mph, at WOT.
It doesn't matter if Manual or Automatic, it's still two gears. and one shift.

However the automatic has an infinitely variable hydraulic gear ratio inside it that at WOT varies somewhere between 1.8>1.1 depending on the input torque to output resistance. That is really, almost exactly like an automatically shifting full gear ratio; so really, from a dead stop, a 3-speed auto is performing like a 4-speed auto.
and from a dead-stop, stall-speed is acting like clutch.
If you match your engine to this powertrain, and you have adequate traction ..... a streeter with an automatic is hard to beat . If you match that to the governor system, and a shift-kit, and just leave it in Drive, it will or could be deadly repeatable.
 
DusterFrank said:
Here is a screen capture of what was sent to me. I don't see any mention of pedals.View attachment 1716303778:
Click to expand...

Get another quote from a different rep for the perfect fit kits or whatever they call them. It'll be a couple grand more than that but it'll come with pedals, master cylinder, hydraulic throwout bearing etc.

I haven't gotten mine on the road yet but I'm close. I did the TKX install. It's not much more work than going from auto to a 4spd. Same skills are required. You just need to do a little more work when it comes to the tunnel and if you're going hydraulic then it probably requires less work than figuring out the mechanical linkages and pivot ball and all that. I feel like secondary level skills aren't required to do a TKX over a 4spd. Plus if I can do it, then anyone is capable.
 
I used to love the street guys that insisted in a rolling start, - not knowing you have 1st gear "coast" valve body.
Like pulling the trigger at speed .
jmo
 
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