Longbed driveshafts
 

To the guys that race longbeds,

What are you using for a driveshaft? I'm having vibration issues with a 3 1/2" mild steel shaft at high speeds and high rpms and am trying to convert back to a HD-style 2-piece shaft. I'm curious as to what everyone else is using.

Thanks in advance!

Re: Longbed driveshafts
 

I run a custom 2 piece on mine.

Re: Longbed driveshafts
 

Thanks for the reply!
I had a local shop build a custom 2-piece for mine, also. It's based on a 2-piece shaft from a 68' C-20, which uses the HD-style carrier bearing.

Have you had any trouble out of your carrier bearing?

Re: Longbed driveshafts
 

No problems yet, my truck is 4 - linked so doesn't have the factory crossmember, actually my truck has no factory crossmembers at all just the frame rails are stock.

So anyway not sure that the steady bearing is even from anything in particular or just a heavy duty universal piece, guy that did the 4 - link had it built. So far the only thing I've ever hurt on it was I ripped apart the trans yoke, it split and ripped apart, went to a chrome moly piece after that, the rest has survived fine so far.

Re: Longbed driveshafts
 

Cool. Glad to hear that it has held up for you. Hopefully mine will do the same.

Thanks again for the input!

Re: Longbed driveshafts
 

pstds carbon fiber 69" long on mine. held a 1.4x 60 ft at 4000 lbs so far. hoping for low 1.3s next year. lifetime replacement warranty, but they aren't cheap.

Re: Longbed driveshafts
 

What carbon fiber shaft did you get? Diameter?

Thanks

Re: Longbed driveshafts
 

I'm pretty sure it's 3.75" give the guys a call and they will hook you up. Received mine in about a week. Light as it gets.

Re: Longbed driveshafts
 

Re: Longbed driveshafts
 

Anybody run an aluminum single piece driveshaft on a long bed? Almost to the point where i need to get a drive shaft made for my 65 long bed. turbo 5.3 ls and 4l80e will be around 550-600 hp at the wheels. Going to leave off the foot brake no transbrake yet

Re: Longbed driveshafts
 

Gotta look at the critical speed for the length, power, and weight. Another reason I went with the carbon fiber was if it breaks, damage will be minimal.

Re: Longbed driveshafts
 

For those of you running a 2 piece driveshaft which type of carrier bearing are you using? The aluminum and poly type that can be bought through ccp? or the wide oem type?
https://westernchassisinc.com/images...erbearingA.png
https://autoplicity.com/content/imag...03398696_0.jpg

Re: Longbed driveshafts
 

I would never use that POS light duty carrier bearing up top. Those are why so many people dislike 2pc driveshafts. I always use the HD carrier bearing on the bottom.

Re: Longbed driveshafts
 

I'm planning on having one made in the next couple weeks. The shop I'm using recommended a 4" alum shaft for my truck. ~71" length.

Re: Longbed driveshafts
 

What is your gearing? I've got a t-56 with a 4.56 rear. 28" tall rear tires. Dyno'd at 590 hp on 87 octane at the flywheel. Haven't had it on a chassis dyno yet (still reassembling the truck).

The Driveshaft Shop (driveshaftshop.com) told me last week, after they suggested it, that a one-piece aluminum driveshaft 69" long at the predicted max rpm (based on 160 mph) would not hold together. They said a carbon fiber probably wouldn't either and I needed a two piece steel. That was mid last week and I still have not heard back from them.

I might call Denny's Driveshaft this week and see what they would put together. The Driveshaft Shop has a good repuation and they are local but i'm not impressed with them right now.

Re: Longbed driveshafts
 

John what max rpm did you use? Predicted rpm at 160 at 1 to 1 or the max you plan to turn your engine? My little calculator shows 8770 in 4th gear and a bit over 7000 in 5th for 160
Jimmy

Re: Longbed driveshafts
 

You have a lot more going for you than i do. Mines just a little mild 402. For now I'm just sticking with the stock 3.08 gear and the 4l80e. After I posted this, I shopped around and found a reputable guy that's gonna build me a steel shaft for about half the cost of the aluminum.

Re: Longbed driveshafts
 

They came up with 8755 rpm. Not sure what calculator they used.

I ran an online calculator I found to figure out theoretical top speed and it was over 240 mph. I think I used a max rpm of 6,500 rpm and even with the 4.56 rear, the double overdrive (0.50 6th gear) sets it up for bonneville. I'd probably need 1,200+ hp to get THAT kind of speed out of this big brick so figured 160 mph was reasonable (if I was stupid enough to try to get going that fast).

Re: Longbed driveshafts
 

I think right now mine is a 403 (6.0 stroker). I've got a stupid amount of money in it but happily, it shows.

Re: Longbed driveshafts
 

I would be looking at pulling gear out to get the drive shaft speed down to 6500 at 160 and that will also help the pinion bearings survive for a long top speed run. It will take a lot of power to get to 160 even with the drag that a truck produces. Then there is the nut factor at speed with the poor aerodynamics and little or no down force.
Jimmy

Re: Longbed driveshafts
 

That gear is way too much fun around town to change out. I just need to get realistic about an anticipated top speed. I doubt I'll ever really get higher than 120 for a few seconds on the interstate. Not sure what it might pull in the 1/4 mile.

thanks

Re: Longbed driveshafts
 

There is always a taller tire.
Jimmy

Re: Longbed driveshafts
 

This, I recently rebuilt the posi and trans and was contemplating a gear swap from 4.11 to 3.42. Tires are cheaper and easier.

I also run a 2 piece with the hd carrier. There isn’t a time I’m driving I don’t abuse my truck. I’ve done 1/8th burnouts, donuts, rolling burnouts on the highway. Nothing wrong with a 2 piece.

Re: Longbed driveshafts
 

I've got Precision in Tampa building me a 2-pc steel driveshaft. They also recommended i upgrade my pinion yoke (as that would be the next weakest link) so I am doing that as well. Should see everything here this week.

When they asked what my top speed would be I said "you tell me what the limit on the shaft is." In reality, the only time the truck will even see triple digits is in the quarter mile and the occasional freeway on-ramp/short burst (just because). I still have to ask Matt what the critical driveshaft speed will be for my setup but whatever it is I'll just use it as my speed limiter.

I've got 20's all around but should be able to get a slightly taller tire out back when these ones get spent (they're still new).

Re: Longbed driveshafts
 

Fit the new 4" steel shaft up this week. It was pretty light, almost seemed like aluminum but wasn't. Im happy with it for $250. They were able to use the stock yoke from the 4l80e and the small'ish 1310 rear joint. Should be fine for my setup. I wont know for a little while till I get it on the road though.