YOUR THOUGHTS,, Replace U joints with drag slicks?

Discussion in 'The Bench' started by stangman, Feb 19, 2018.

  1. stangman

    stangman Well-Known Member

    A friend suggested that since I built my 350 motor ( approx. 400 hp) said I should replace u joints with stronger ones. I bought a set of 26 x 15 x 8 Hoosier Drag Slicks. Looking for input. Stock auto trans. No stall converter. 3;42 gears. What say you? If so what brand is recommended? Thanks
     
  2. Thumper (aka greatscat)

    Thumper (aka greatscat) Well-Known Member

    A question, are you using the stock 350 driveshaft? If so its a 2 piece and for reliability should be replaced, and use stronger u joints than stock. If its already a 1 piece and stock u joints you should step up ,and if running slicks put in a driveshaft loop.
     
    300sbb_overkill likes this.
  3. stangman

    stangman Well-Known Member

    It is a one piece shaft. stock as far as I know.
     
    britt'sStage 1 likes this.
  4. Bens99gtp

    Bens99gtp Well-Known Member

    Nothing wrong with having a good quality ujoint. It's only like 50 bucks in parts. X2 on shaftloops......a shafts out of control can really do a lot of damage
     
  5. stangman

    stangman Well-Known Member

    Thanks guys appreciate the advice. Its all about safety!!!
     
  6. GS Spoken Here

    GS Spoken Here Well-Known Member

    I think what Gary means is that most Skylark/GS auto stock drive shafts have a rubber insert making them two piece with rubber between and can be a problem.
     
  7. Smokey15

    Smokey15 So old that I use AARP bolts.

    /\/\/\ This. Use the HD joints without grease fittings. If you plan to hit the track, most tech officials will tell you to run a loop if your are running slicks. Personally, I won't race w/o at least a front loop.
     
  8. 436'd Skylark

    436'd Skylark Sweet Fancy Moses!!!!!

    i don't think you are going to hurt anything yet with a stock converter.
     
    Mark Demko and 72buicklark like this.
  9. Thumper (aka greatscat)

    Thumper (aka greatscat) Well-Known Member

    Not likely, look at the rear section of the shaft, if the small diameter section goes inside the larger main section its 2 piece.
     
  10. StagedCat

    StagedCat Platinum Level Contributor

    Gary's right, look closely.......
     
  11. jay3000

    jay3000 RIP 1-16-21

    You may just replace something that works well with something that doesn't
     
  12. yachtsmanbill

    yachtsmanbill Well-Known Member

    So is that 2 piece shaft fitted and socket welded (male into female?) or is it spun welded. I didnt pay attention last week when I re-jointed and installed it; always willing to learn! ws

    IMG_7628.JPG

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  13. TrunkMonkey

    TrunkMonkey Well-Known Member

    The two piece drive shafts were a "dampening" device.

    It is two piece tube, larger and smaller. The smaller slips in the larger and then rubber was poured in and vulcanized to create an isolated drive shaft to help with harmonics and vibration being absorbed within the mass, and dissipated in the rubber.

    Over years, the rubber looses some elasticity and may not be able to handle the greater torque. And put some real good hook up between the rear tires and the output of the tranny, and the weakest link is gonna give it up.

    And often it is that drive two piece drive shaft.

    Gonaa say, I hate other people spending my money, but if one puts as much into a car as most people, throw a few hundred dollars on a reciprocal insurance policy.

    I was with a friend in the 70s, who had a '56 Chevy and a big block with a Vertigate shifter and missed trying to downshift at high RPM, over revved and twisted his two piece shaft, and we planted the front of what was left and did lucky for use all we managed was a 180.

    (leaf spring wrap pulled the drive shaft apart after the torque broke the rubber "connection")

    But, it made me a firm believer in shaft hoops, and not doing **** to impress the girls on the street.

    No, not street girls. Wholesome girls, who snuck out and watched us "Drag Douglas" in Wichita , back in the day.
     
  14. Briz

    Briz Founders Club Member

    Heres what I learned about this in the last month. Went to the track several Saturdays ago. Weather and track conditions were as good as I've ever seen. Cool crisp dry air ,perfect for making power. 1st qualifying round. Did my usual burn out, staged, hit the trans brake and matted the loud peddle. Let go of the button for a .037 light. There was a loud BANG and the car rolled about 10' and stopped. Thank goodness for a rev limiter. Anyway, broke the spool. twisted and stripped the splines off the axles but didnt brake the stock shaft or U joints. After rebuilding and up grading everything that broke a buddy suggested I install 1350 solid U joints in place of the stock 1310's with the zert fitting. Got on Summit Racing, ordered the joints. about 35.00 each.Came the next afternoon. Guess what, ya cant put a 1350 joint in place of a 1310. Cups are bigger and its wider. That lead to buying a larger yolk for the TH400 a larger heavy duty yolk for the pinion and a completely new super duty drive shaft.
    Now, I ran that stock shaft for 3 years in the Capt America Skylark and nearly 2 years in the Regal. The last year of that putting 700hp trans brake launches on slicks and a prepped track. I was probably really lucky the last year but it didnt break. At your power level Id install a loop and forget about it.
     
    300sbb_overkill likes this.
  15. redbuick

    redbuick Well-Known Member

    If you have any doubts about that driveshaft or U-joints, by all means upgrade both and add a loop too, it's really not a lot of money for peace of mind. Losing a questionable drive shaft can ruin your day and end up costing a lot of money, or worse.
     
    Smokey15 likes this.
  16. sean Buick 76

    sean Buick 76 Buick Nut

    Add a driveshaft Loop too...
     
  17. StagedCat

    StagedCat Platinum Level Contributor

    Here's a shaft out of my Sportwagon........

    Resized_20180220_071850.jpg Resized_20180220_071904.jpg
     
  18. 12lives

    12lives Control the controllable, let the rest go

    Where are you all buying quality driveshafts?
     
  19. Briz

    Briz Founders Club Member

    Had mine built to my specks at a shop in Jacksonville. http://drivelinejacksonville.com/ Cost was 200.00 less than summit and I had it in under 3 days
     
  20. Bens99gtp

    Bens99gtp Well-Known Member

    I just had a shaft built for 90ss pickup now sporting a 650hp 502. We just added a gear vendors od unit. They sent me the yoke with the purchase. Simple called called custom clutch and joint in hilliard ohio. They told me how to measure and they even came picked up the yoke and brought the new shaft back. 248 bucks.

    I have been running a shaft they built me for about 10 years now, no issues

    Call and talk to Mike 614-850-0337. Just tell him Ben from Branham Automotive gave you the number. I'm sure they can ship too.
     

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