Safe driveshaft length??

[Titanium Soldier]

Hello all, I am working on a bobber project , but i am doing it a little bit different than the norm. i am installing my axle a bit further back than the usual bobber which (please correct me if i am wrong) usually requires a 5-6" longer driveshaft. I need at about 12 inches further. I measure 63" from flange to flange. So i took it today to the shop (adams metalizing and grinding in lancaster CA) and the driveshaft guy told me it is too long and probably will twist. I know that there are all sorts of diferent things that can make it or break it, diameter wall thickness length and material, But i have seen some pretty long a$$ driveshafts and 63" doesnt sound to bad to me! BUT..... i am not a pro, that being said, has anyone else here lengthened one to that length and what were the results?? and do any of you fellas also think that its to long?? Please give me ur advice or critisism!!

-Tom

 

[topo]

can you mount a carrier bearing . you may be able to make the first shaft the right length so that you could reuse your old drive line or get it cut down .talk to your drive line shop you don't want any problems .

 

[Titanium Soldier]

can you mount a carrier bearing . you may be able to make the first shaft the right length so that you could reuse your old drive line or get it cut down .talk to your drive line shop you don't want any problems .

I had thought of that, but i would really like to stay away from it if possible. I had planned on just installing safety straps around it, incase it lets go. hopefully they wouldnt need to be used!!!! besides we are fortunate enought to have front wheel drive to get us home!!

 

[jtron79]

I would say talk to a truck drive line shop. No disrespect but those guys probly only deal with little 4x4 drivelines. Our dumptrucks at work are atleast 70"+ and it's just my but try to steer clear of a carrier bearing, they wear out quickly and are kind of a pain to deal with.

 

[Titanium Soldier]

I think i will stop at one tomorrow after work. Do those dumptruck driveshafts have a carrier??? Like i said before, i really dont think i NEED one but again i am a jet mechanic lol we dont have driveshafts

 

[jtron79]

No carrier. Honestly you'll bend it first then you'll know its too long

 

[Awesome Possum]

I did my bob about the same length as yours. I just gave them the measurements the way they said to, and they lenthened it by about 13". Only 65-70 miles so far, but so far, so good. I had Inland Truck Parts Company do it, and it cost $191.00.

 

[Titanium Soldier]

Awesome, good to hear yours is working out, makes me more relieved!!

 

[HanksDeuce]

My local truck shop, Margot Inc., said that DOT will not allow a driveshaft longer than 68 inches without a carrier bearing. My bobber shafts are nowhere near that. Good luck!

 

[DBLDUECE77]

Thats funny because the aluminum driveshafts in the newer chevy duramax trucks are over 78" and they work just fine.

 

[davey8943]

FWIW, Spicer has something to say about speeds, lengths, angles, etc here:

http://www2.dana.com/pdf/J3311-1-HVTSS.PDF

There is a table on Page 18 that may be of particular use for you...

In case it gets moved, I'll try to upload it as an attachment....

Happy Bobbing!
Dave

 

[hndrsonj]

Good link Dave. Looks like as long as the right size tubing is used will be OK. (pg 18 )

 

[Titanium Soldier]

Thank you all for your inputs and info, very helpfull PDF dave!

 

[73m819]

http://www2.dana.com/pdf/J3311-1-HVTSS.PDF

This should be read by EVERYBODY that A--bobs a deuce, B--Does a lift for tire clearence, C-- a go faster, D-- motor repower

 

[HanksDeuce]

Based on that PDF with a maximum engine rpm of 2875 and a 5th gear ratio of 0.79 that would be: 2875 / 0.79 = 3639 rpm (max driveshaft rpm).

The chart indicates a max length of 45 inches for a 2.5 inch, 0.083 wall tube.
The chart indicates a max length of 64 inches for a 3 inch, 0.083 wall tube.

I don't have my deuce at my house. What size is the deuce rear driveshaft?

 

[Titanium Soldier]

I dont know, but i would say its close to but probably a tad over 3" diameter. judging by how wide a $1 bill is folded in half

 

[quickfarms]

you got it

drive shaft legnth is a factor of the tube diameter.