1964 plymouth valiant Slant six to 340

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64whiteghost

64whiteghost

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Hello guys. I purchased my first car and im finally building it how i truly wanted to when I was 16. I have a 1968 340 that will be built up to 450 hp. I have everything settled except for the drive shaft. Any suggestions ? Im sure I cant use the orignal one or can I ?
PS i will be using a 8 3/4 with 3:91 gears

Sorry guys forgot to mention that I have a 64 A833 that im rebuilding which will go into this car. I have been contemplating going with the QA1 drive shaft since it will be having a QA1 front and back suspension already.

Any thoughts ?

Btw Im in Torrance, California

IMG_5089 (1).jpg
 
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You would probably have to shorten it a bit and
perhaps adapter U Joints depending on rear end and
if you change to 727.
 
i'd recommend having a shaft made for this particular application. while you could have the original shaft shortened and rebalanced you'll probably wind up needing to run adapter u-joints as john mentions because of the difference in yoke sizes at the rear.

at the front you may have a ball and trunnion joint which would would need to be swapped to a more typical u-joint to mate with the output of the newer transmission you're likely going to be using.

also, i wouldn't be trusting nearly 60 year old parts to handle the power levels you're planning on subjecting them to, especially considering what parameters and power levels they were originally designed to operate in.

finally, modifying your current driveshaft would probably cost dang near the same as having a new one built.
 
Probably be a good idea to go thru the suspension change radiator torsion bars rear springs. Unless you have already done all that.
I have a 64 that was transformed from a slant to 318.
Half *** hack job. I have since fixed that mess. Now have A upgraded 318 roller going in .
It will have enough power for me.
Not going to see the track. Good luck with your project.
 
I would recommend using a 904 or 4 speed, that way you won't have to modify the pinch area on the firewall. You can use the driveshaft from an 8 3/4 Barracuda, Valiant, or Duster. Probably an 8 1/4 car also.
 
66fs said:
I would recommend using a 904 or 4 speed, that way you won't have to modify the pinch area on the firewall. You can use the driveshaft from an 8 3/4 Barracuda, Valiant, or Duster. Probably an 8 1/4 car also.
Click to expand...
64 Val has 106" wheelbase. 67 and newer 2 doors went to 108".
Ball and trunnion on trans in 64.
IIRC the early shaft is only 2-3/4" diameter, newer are 3".
A 66 shaft could work because it's the same wheelbase and u-joint.

If it was me I'd get a new one made or a good longer one shortened. I like to do things once and move on without having to do it again later.
 
Hugo Gonzalez said:
Hello guys. I purchased my first car and im finally building it how i truly wanted to when I was 16. I have a 1968 340 that will be built up to 450 hp. I have everything settled except for the drive shaft. Any suggestions ? Im sure I cant use the orignal one or can I ?
PS i will be using a 8 3/4 with 3:91 gears

View attachment 1716090448
Click to expand...
Since you're going from a 6 to an 8, you won't be able to use your existing trans anyway. You didn't mention if it's a stick or an automatic, but that's kind of a moot point anyhow. The main issue is what transmission you are GOING to use. It's a whole new can of worms on it's own. Until we know that, it's useless to speculate, other than to say you WILL need a new driveshaft.
 
KosmicKuda said:
64 Val has 106" wheelbase. 67 and newer 2 doors went to 108".
Ball and trunnion on trans in 64.
IIRC the early shaft is only 2-3/4" diameter, newer are 3".
A 66 shaft could work because it's the same wheelbase and u-joint.

If it was me I'd get a new one made or a good longer one shortened. I like to do things once and move on without having to do it again later.
Click to expand...
Front wheels were moved forward. The drive train is in the same relationship. He will need a different trans, since the /6 trans will not work with a 340. Did it too many times. Diameter of the driveshaft is not the limiting factor. It is the u-joint, you just need good ones.
 
Thank you all for your responses.

I did forget to mention that the car will be a 4 speed I have a 64 A833 that Iam currently rebuilding. As far as the driveshaft I have been looking at the QA1 carbon fiber drive shaft. If you know of another brand that is not as expensive that would help
 
Old man ray said:
Probably be a good idea to go thru the suspension change radiator torsion bars rear springs. Unless you have already done all that.
I have a 64 that was transformed from a slant to 318.
Half *** hack job. I have since fixed that mess. Now have A upgraded 318 roller going in .
It will have enough power for me.
Not going to see the track. Good luck with your project.
Click to expand...
Thanks for your reply,

Yes the whole suspension will be new. I ordered a whole QA1 front and back with dual adjustable shocks, sway bars and leaf springs. Also got a SSBC USA disc brake kit
 
Hugo Gonzalez said:
Thank you all for your responses.

I did forget to mention that the car will be a 4 speed I have a 64 A833 that Iam currently rebuilding. As far as the driveshaft I have been looking at the QA1 carbon fiber drive shaft. If you know of another brand that is not as expensive that would help
Click to expand...
As you probably know, your '64 four speed will have a ball & trunnion output shaft on it. And while your current driveshaft also has a ball and trunnion front joint, coming from an automatic (which is longer than the four speed) it will be far too short to use. You're probably going to strike out trying to get anybody to build you a ball & trunnion driveshaft in this day and age (not to mention a severe lack of new/rebuild parts for the B&T), so my advice would be to have a new shaft built as per this article:
Early Valiant Barracuda Club - ball and trunion U-joint conversion
 
Just FYI, if you had a later 4 speed that used a conventional u-joint, a driveshaft out of a 108 inch wheelbase A body with 8 3/4 rear and either 4 speed or 3 speed manual will be exactly the right length. Also (I think) a 904 automatic. 727 automatic is longer and a driveshaft out of that won't work.

Depending on the trans of the donor car, you might have to change the front yoke of the driveshaft. The driveshaft in my 65 Barracuda came from my Mom's 71 Duster 340 3-speed manual, and I had to change the front yoke to fit the larger 4-speed output shaft. No other mods necessary.

Now I did this a pretty long time ago. Used A body driveshafts in usable condition are a lot harder to find these days. Plenty of places can make you a new one, though.

BTW, the 64 trans you plan to use has a 3.09 low gear. Later versions had a 2.66 low gear. Multiply the low gear ratio by the rear axle ratio to get your overall low gear ratio. I've run both trannies, and let me tell you, the 2.66 low gear and a cammed 340 purely sucks off the line with 3.23 gears. The 3.09 low gear works great with 3.23 rear gears. The difference really is amazing. Since you'll be running 3.91 rear gears, the 2.66 low gear would work fine, and the 3.09 low gear might even be too much.
 
You could use your original driveshaft, but it would have to be shortened. Good driveshaft shop could do that easily enough. Rear u-joint may or may not fit the rear axle, depending on the size of its u-joint. That can be addressed either by changing the rear axle yoke or by using a combination u-joint.

If your shaft is in good condition, it would probably be strong enough, but it's (I think) on the small side (2.5 inch diameter). Also, if your ball and trunnion joint is worn, the parts to rebuild them are getting more scarce and more expensive all the time.

There are companies that can build you a slip joint driveshaft that will bolt up to your ball and trunnion style transmission. I did this for my 59 Dodge. See Driveshaft Specialist Home I'm sure there are others.
 
Hugo Gonzalez said:
Hello guys. I purchased my first car and im finally building it how i truly wanted to when I was 16. I have a 1968 340 that will be built up to 450 hp. I have everything settled except for the drive shaft. Any suggestions ? Im sure I cant use the orignal one or can I ?
PS i will be using a 8 3/4 with 3:91 gears

Sorry guys forgot to mention that I have a 64 A833 that im rebuilding which will go into this car. I have been contemplating going with the QA1 drive shaft since it will be having a QA1 front and back suspension already.

Any thoughts ?

Btw Im in Torrance, California

View attachment 1716090448
Click to expand...
If you're truly going to use the '64 833, have a driveshaft built with a rear u-joint that matches the pinion flange on your 8 3/4 rear, and get the ball and trunnion elimination kit so you can use a standard u-joint in the front also.....hopefully one that matches the rear for simplicity. The other issue you will run into doing that conversion is choosing and using a bell housing/clutch setup that will fit properly. A stock '64-6 273 cast iron bell housing, flywheel and dust cover will work great if you also use a B-van 6 cyl clutch and heavy duty pressure plate. If you go with an aluminum bell housing and matching flywheel/clutch/dust covers, you will want to make sure the bearing retainer hole matches the small bearing retainer on your 833. You will also most likely need to modify your clutch linkage for either setup if you plan on re-using your 6 cyl. setup. As for your question as to whether you "can" use your old driveshaft, if the rear u-joint matches the pinion flange on the 8 3/4 (or you get the conversion joint), and you're willing to shorten the shaft a bit to account for the 8 3/4's larger size over the original 7 1/4", sure, it will fit. Not a great idea doing that. Even though Max wedges and Hemi cars had the ball and trunnion joints, they were the bigger version than what your '64 6cyl 7 1/4 uses. With 450 HP, it would be a grenade with the pin pulled IMO.
 
I may have a drive shaft for you, it came out of a 64 dart with a 4 speed and a 8 3/4 rear end. if it is the same length then it should work for you.
it is better than the stock ball and trunnion. what I am not sure of is the difference in wheelbase between the 64 dart and the 65 valiant. What I will say is good luck finding the correct speedo gear for the 64 833.
64 Dart Driveshaft Length
 
66fs said:
I would recommend using a 904 or 4 speed, that way you won't have to modify the pinch area on the firewall. You can use the driveshaft from an 8 3/4 Barracuda, Valiant, or Duster. Probably an 8 1/4 car also.
Click to expand...
Is not the 64 valiant a 106 Wheelbase rather than the 108 of the later
cars? I thought I remembered that = If so, the driveshaft would be too long.
 
GTX JOHN said:
Is not the 64 valiant a 106 Wheelbase rather than the 108 of the later
cars? I thought I remembered that = If so, the driveshaft would be too long.
Click to expand...

The drive train Drive train is in the same position, only the front wheels were moved forward. Driveshaft is the same length as a Duster, 65-69 Barracuda, and Valiant with a 904, A/F-Body 4 speed, and an 8 3/4 or 8 1/4 rear. U-joint should be the small one. Looks like he wants to use the 64 A-833 4 speed, so probably the best option would be to shorten and balance his driveshaft. The original driveshaft will hold up. Darts are longer between the trans and rear.
 
Since a '64 never came with an 8 3/4, there are no factory ball and trunnion driveshafts that will just bolt in. There may be a few out there from cars that had an 8 3/4 installed at a later date though. If you have to cut it shorter and rebalance, you may as well upgrade to a better driveshaft so you don't have to worry about breaking a stock one. If it's a 741 case 3rd member, yeah, probably small u-joint, 742 or 489 case could have several options depending on what it came out of.
 
cudamark said:
Since a '64 never came with an 8 3/4, there are no factory ball and trunnion driveshafts that will just bolt in. There may be a few out there from cars that had an 8 3/4 installed at a later date though. If you have to cut it shorter and rebalance, you may as well upgrade to a better driveshaft so you don't have to worry about breaking a stock one. If it's a 741 case 3rd member, yeah, probably small u-joint, 742 or 489 case could have several options depending on what it came out of.
Click to expand...
Mostly agree, but I think it would be significantly cheaper to shorten and balance the old shaft than to have a new one made up. At least, that was the case when I first put an 8 3/4 in my 65 Barracuda back in the seventies. Only reason I ever replaced that shaft was I switched to a later trans, then found out a Duster 340 manual trans drive shaft bolted right in despite the wheelbase difference between the Duster and my Barracuda. That's also when I found out about the difference in low gear ratios. Was an unhappy camper for a couple of years until I found out my original gearset with 3.09 low gear fit inside my newer trans.
 
Cheaper, sure, I just don't think that 6cyl ball and trunnion driveshaft is going to hold up to 450HP.....not for long anyway.
 
Hugo Gonzalez said:
Thanks for your reply,

Yes the whole suspension will be new. I ordered a whole QA1 front and back with dual adjustable shocks, sway bars and leaf springs. Also got a SSBC USA disc brake kit
Click to expand...
nice! that should be a really lovely set up.

Hugo Gonzalez said:
Thank you all for your responses.

I did forget to mention that the car will be a 4 speed I have a 64 A833 that Iam currently rebuilding. As far as the driveshaft I have been looking at the QA1 carbon fiber drive shaft. If you know of another brand that is not as expensive that would help
Click to expand...
as mentioned above, here is where you're going to run into problems with the ball & trunnion output.

so, you either convert the 4spd to standard output and then run a typical yoke OR you'll need to build a shaft with a conversion joint and a B&T eliminator. which exists, somewhere.

when i did mine ages ago in the 64 dart i wound up using an E-series ford van joint and having the shaft built locally-- i had also swapped the rear to an 8.25 at the time. so in collaboration with the drive shaft shop and some careful measuring on my part i only spent an arm instead of an arm and a leg. so it was mostly painless.

this may be a moot point, but have you looked into summit yet? they have driveshafts and something there may work, or at least get you part of the way there and then you could be on track to have some work done locally. but again, it's highly dependent on what your output is.
 
Yea Thats why Iam considering the QA1 Carbon fiber drive shaft. This is my dream build so im going to do it right the first time.
cudamark said:
Cheaper, sure, I just don't think that 6cyl ball and trunnion driveshaft is going to hold up to 450HP.....not for long anyway.
Click to expand...
 
trapster said:
I may have a drive shaft for you, it came out of a 64 dart with a 4 speed and a 8 3/4 rear end. if it is the same length then it should work for you.
it is better than the stock ball and trunnion. what I am not sure of is the difference in wheelbase between the 64 dart and the 65 valiant. What I will say is good luck finding the correct speedo gear for the 64 833.
64 Dart Driveshaft Length
Click to expand...
Send me pictures and pricing on the drive shaft please.

And the correct speedo gear isnt remade ?
 
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