Is it safe to use the driveshaft from a slant 6 904, on a v8 360 904?

-
myasylum

myasylum

Well-Known Member
Joined
Sep 18, 2008
Messages
1,740
Reaction score
4
Location
Las Vegas, NV
My Slant 6 engine came with a 8 1/4 rear end.
I have now a stroker 410 with a 8 3/4 rear end.
Strangely enough the driveshaft fits pretty damn well. I have been driving it that way for about a year, but I am really nervous keeping that old slant 6 drive shaft everything I beat on it a bit. If it fits well, should I be o.k. or is that driveshaft to weak?

I just did some measuring and my rear end is a 489 case and the cap diameter is 1.078. The overall length from the housing to the pinion yoke is 52 1/2".

Am I just real lucky that this driveshaft works for me, or should I be concerned?

I went to Denny's driveshaft and the 3" driveshafts go for around $400.00. Or?? Just keep this one for free!?! Any suggestions?

Thanks!!
 
I think you'll be fine. I compared my S6 to a B-Body shaft when I was doing mine. I used the 6 - had to change the slip yoke and be shortened anyway. Install some fresh u-joints or conversion joints.
 
Don't use conversion joints with performance, you're playing with fire.

If you aren't racing the car, or doing lots of high speed driving then you'll be ok....

If you feel nervous see your local driveline shop you'll have less problems.
 
See now, that kind of hangs me up. No I don't do alot of racing, but I do like to smoke the tires and beat on it a bit. I mean the stock slant six is what 110 hp, now I'm dealing with about 400 plus, that seems like a lot more then that shaft has has to endure. So I guess thats what I worry about. If you guys think it should be safe I'll go with it, and just get new U joints. It would be much cheaper admittedly.
Thanks!
 
myasylum said:
See now, that kind of hangs me up. No I don't do alot of racing, but I do like to smoke the tires and beat on it a bit. I mean the stock slant six is what 110 hp, now I'm dealing with about 400 plus, that seems like a lot more then that shaft has has to endure. So I guess thats what I worry about. If you guys think it should be safe I'll go with it, and just get new U joints. It would be much cheaper admittedly.
Thanks!
Click to expand...

For saftey install a drive shaft loop along with the new U joints and go for it. You say this has stayed together for a year already so why wouldn't it continue to work?
 
You have to consider traction. If you dont have suspension upgrades,low gears or sticky tires,chances are tires will break loose before the driveshaft twists or breaks joints.
 
Supershafts said:
Don't use conversion joints with performance, you're playing with fire.

If you aren't racing the car, or doing lots of high speed driving then you'll be ok....

If you feel nervous see your local driveline shop you'll have less problems.
Click to expand...
I ran 7260/7290 crossover u-joints in my race car running over 100 passes at 11.00-10.80@123mph,never had 1 problem with u-joints.Was I just lucky??
 
"Life is like a roll of toilet paper. Either youre on a roll or taking crap off an ahole"

DD , i fricken love it LOL
 
Yes, I drove it for a year, but not very often due to being pariniod. I thought about a driveshaft loop, the one that I liked was $250.00. It connects right to the transmission brace. I just thought that was a bit pricy and wanted to make sure what route I was going to take with the driveshaft first. I do have HD Springs, and Sure Grip, 3.21gears. so that was a bit of my concern, because there is a bit more stickiness to the road then just a one leger.
Thanks much guys! You rule!!
 
Can you replace u joints yourself? Or is that something you should take to a professional shop? Also of If have 1.078 cap diameter is there a u joint you suggest?
 
myasylum said:
Can you replace u joints yourself? Or is that something you should take to a professional shop? Also of If have 1.078 cap diameter is there a u joint you suggest?
Click to expand...
Yes you can replace the U-joints yourself,aslong as you have a vise,big hammer.I just use a socket to press out the caps.:D
 
You can also find universal fit drive shaft loops for as low as $25 from Summit but you'd have to do some fab work to use them. Either way, it'd be a good idea.

I don't know what, if anything, changed on the crossmember in '73 for that Mancini one.

You'd get a replacement (small) 7260 for the front and a 7260 to 7290 conversion joint for the rear. It's half small and half large - small half on the shaft, larger half connects to the 8.75 rear.

The 7260 was even used on Dodge dually trucks so it's not like they're puny.
 
When did driveshaft loops get so expensive......man i must really be old:profilel:

Thanks 440, that was close....lol
 
well..here is one from experience....drive shaft ripped apart...conversion u joint still attached to rear end yoke...

the u joint get my vote to be stronger then the driveshaft...and look it has a grease fitting too.

happend a month ago at MATS..in 71 Demon 360
 

Attachments

  • IMG_0472.JPG
    89 KB · Views: 481
So 70AARCuda... From your experience then are you stating that it would be best to look into a new driveshaft? That looks like that sucks. Or are you just saying to make sure I get the driveshaft loop? Maybe one for the rear too! :?
Did it tear up the bottom of your car?

The rear yoke on the rear end measured at 1.078. that still would get the larger conversion?
 
No..did not damage car the as the two driveshaft loops contained it...It happened on the starting line also. That was a stock driveshaft that I bought from someone on FABO.....

I had a new driveshaft made by a driveline shop for 215 dollars including new u joints....

I was launching with a transbrake using a 2 step.....if you are footbraking...i would doubt you would have any problem with a stock driveshaft..
 
DRIVE SHAFT LOOP CHEVY FORD MOPAR NHRA IHRA $24.99 for a universal loop.

EVERY BODY KNOWS WHAT THESE ARE FOR, IF YOU HAVE NEVER EXPERIENCED A DRIVE SHAFT FAILURE AND HAD IT BEAT YOU CAR TO DEATH, DON'T CHANCE IT , GET ONE BEFORE IT GETS YOU...! REQUIRED EQUIPMENT FOR NHRA AND IHRA...!

UNIVERSAL FIT ON JUST ABOUT ANY CAR OR TRUCK...

http://www.ebay.com/itm/DRIVE-SHAFT...pt=Race_Car_Parts&hash=item5649524b23&vxp=mtr
 

Attachments

  • 016b_1.JPG
    8.3 KB · Views: 444
http://www.classicindustries.com/mopar/parts/mn7014.html

1967-76 MOPAR A-BODY CUSTOM-FIT DRIVE SHAFT SAFETY LOOP
These NHRA-legal driveshaft safety loops are custom fit for all 1967-76 Mopar A-Body models. One-piece loops are fixture-welded with an oversized ring cut from DOM tubing for maximum clearance. Powder coated black for durable surface protection. Includes grade 8 hardware and instructions. Made in the USA.

Part Number: # MN7014 $ 69.99 ea
 
Wow! Thanks a lot! I do like the Manci one because it bolts rip the transmission bracing. The other ones look like they bolt onto the floor. Id rather avoid drilling holes in the floor, but I will have too it seems. I don't have the knowledge or tools to fabricate myself.
Thanks for doing the legwork for me!!
 
myasylum said:
Wow! Thanks a lot! I do like the Manci one because it bolts rip the transmission bracing. The other ones look like they bolt onto the floor. Id rather avoid drilling holes in the floor, but I will have too it seems. I don't have the knowledge or tools to fabricate myself.
Thanks for doing the legwork for me!!
Click to expand...

I like the idea of not having to drill on the car but even the MANCINI forces you to do at least one hole.
Take the MANCINI pictures to a local shop and see what they can do for you. Places around here have scrap that would make most of the parts. The only part that would be an issue would be the plate that bolts to the cross member.
 
I'm kind of liking that last one posted. It seems like a good happy medium for 69.95.


Im still wondering about of the rear 8 3/4 measured 1.078. Does that still get the larger conversion?
Thanks!!
 
You must log in or register to reply here.
-

Back
Top