gm leaf spring bushings and synthetic rearend fluid

Discussion in 'The "Pure" Stockers' started by Chris Teed, Dec 20, 2005.

  1. Chris Teed

    Chris Teed Well-Known Member

    About ready to install my 12 bolt rearend in my 68 nova ss 396/375 car pure stock.I have installed a new eaton posi unit;my rearend specialists says not to put synthetic fluid in the rear;because the clutches in a eaton posi are made of keblar and the two ;do not work well together.I have never heard of this ;any help out there .this guys has been building rearend for racers and streecar for 20 years.Any comments on using poly bushings for the front and rear of the rear leaf springs.I do drive the car on the street.But plan to Purestockrace the car also with a 4speed..thanks for any comments or help Chris Teed best et PS 68 nova ss396/350 with 3;42 gear 13;28 at 102mph coming soon 68 nova ss 396/375 with 4speed and 842 aluminum heads
     
    Chris Teed, Dec 20, 2005
    #1
  2. Brian Stefina

    Brian Stefina Well-Known Member

    I had synthetic in the Merc rear. It was a rough chattering mess that no amount of friction modifier could stop. Hard to take even in the pits.

    The last gear change I went back to 80-90 Dino oil.

    Smooth as silk.

    I do know of one other axle that had the same problem. If the friction material is designed for synthetic use it. If not, problems from rear end chatter to, in some trans applications, friction material delamination will happen.
     
    Brian Stefina, Dec 21, 2005
    #2
  3. Chevy454

    Chevy454 Well-Known Member

    I've been running synthetic in our Camaro for 3+ years now...no problems here...as for bushings, I didn't know they came in anything other than rubber! [​IMG]
     
    Chevy454, Dec 22, 2005
    #3
  4. Jeff Sawruk

    Jeff Sawruk Well-Known Member

    I know you can buy bushings in Original rubber, Polyurethane, Aluminum or even have them custom made from Delrin :Brow:
     
    Jeff Sawruk, Dec 22, 2005
    #4
  5. defan238

    defan238 Well-Known Member

    i was also told not to use synthetic with my eaton
     
    defan238, Dec 22, 2005
    #5
  6. Dave H

    Dave H Well-Known Member

    Trannies, too.

    Speaking of four speed Muncies, a friend fried his freshly rebuilt M-22 rock crusher in his 70 442 W30 using synthetic fluid. Liberty (pretty well known transmission place) had rebuilt it and covered it on warranty since they hadn't warned him to not use synthetic fluids. Put in the 90W Goose grease and it's been fine since (over 10 years).

    I think somebody said it above, if it was designed to use the heavy gear lube, probably a good idea to use it. Probably don't shift as slick as the lighter oils and would last in our limited Pure Stock racing (except for the clutch chatter Brian spoke of), but not on the road when it warms up?
     
    Dave H, Dec 23, 2005
    #6

Share This Page