Remember the Rear Leafs are captured in Plates and a 2X3 Box tube above the
Plate on top of the spring....
They don't flex at all... unless you bend a ton of Steel... and nothing is
bent... what they do is rotate around the spring Eye as a Ladder Bar would
rotate around it's front pivot point....
Once set at Ride height.. the car only moves as much as the stiff Shocks
will allow it as well as the air spring...(air bag) to set the Ride height
we added some extra air pressure and it does in fact make the car even
stiffer.... which is good.... as stiff in my case equates to the rear end
not moving much and the pinion angles not changing radically....
This leads us to the thought that the angle can be in the two degree range
and not be a problem... so long as it isn't changing under acceleration...
I have watched the car leave really closely and it doesn't raise... or at
least not perceivably... and you don't feel it in your butt like you do
with a Ladderbar car leaving a starting line...
Needless to say we spent the weekend sorting out pinion angles and trans
positions... I have that 1.5 to two degree angle up out of the trans and
simply matched that in up angle on the pinion...
I started the car on jacks last night and went through the gears... ( I
rebuilt the Trans so I wanted to check it also) and the car picked up a
vibration in forth gear.... took the tires off and Life was good.... no
vibration at all... then I put the 28" tires on and didn't have a Problem
once again.... so as a minimum I have a set of tires that aren't balanced
well also.... easy fix...
So on the end of the day.... my big concern wasn't that I lost a drive
shaft... it was finding and fixing the Problem that caused the Driveshaft
to fail..... I came up with four Problems that I could see...
1. that the drive line didn't have parallel angles front and rear
2. that the Drive shaft itself was a stock unit and not
designed to spin in the 6800rpm range and
started whipping with the unequal rotational velocities...
3. The U-joint was not spinning so the bearings stopped
rotating and the back caps on the
u-joints weren't captured by positive stops... allowing
the caps to come off the Rear
4. the Tires being out of balance aided the whole thing... in just
being a
mess.. this after I
I had them balanced
Wow.. okay so on the end of the day... I feel like I fixed all the Problems
and that the car is safe...and sound .... we are still going to make a
couple of slow passes to check everything out..
Keith Turk...
----------
> From: Joseph Timney <TIMNEYJJ@sterlingdi.com>
> To: kturk@ala.net; land-speed@autox.team.net;
johnbeck@blueridge.cc.nc.us; 110420.3466@compuserve.com
> Subject: Re: Pinion Angles
> Date: Wednesday, June 02, 1999 5:55 AM
>
> Keith,The published rule of thumb for drive shaft angles are;
> Leaf spring 4 to 6 degrees
> Ladder Bar 3 to 4 degrees
> 4 Link Bars 2 to 3 degrees
> The thought process is that the leaf spring will windup more causing the
drive shaft to go upward. You stated that your car has an opposite the
normal condition, as it is very low and the rear is higher than the
transmission tailshaft. I believe your leaf springs ( under course loads)
are flexing a lot, giving you extreme angles. An alignment will not keep
the driveshaft in the car... controlling the flexing will. I think a ladder
bar or 4 link setup is what you need unless you car stiffen up those leafs.
Bruce and John are right...you need to keep the trans and pinion parallel
at all costs !
> >>> "B. Whiting" <110420.3466@compuserve.com> 06/01 4:15 PM >>>
>
>
> -------------------- Begin Original Message --------------------
>
> Message text written by John Beckett
>
> "Keeping the transmissions and the pinion parallel to each
> other.
>
> Your adjustable suspension may need some geometry checks.
>
> John Beckett
> "
>
>
> -------------------- End Original Message --------------------
>
> John is correct on this. The angles must be the same on both the trans
> output shaft and the pinion shaft. The u-joints will split the difference
> for you. In over 30 years of replace u joints, etc. I've always found the
> grooving to be a result of poor lubrication and not a result of
> installation angles. You do want to keep the u-joint angles as low as
> possible. 4 degrees works well. It's a problem of shaft whipping. The
> higher the angles the more the rotational speed of the various parts of
the
> shaft vary from each other. Causes destruction of the shaft! Same problem
> that Big 4X4's have when jacked way up. If you do have to do this sort of
> thing then you need constant velocity joints like what Cadillac uses in
the
> big limo cars. Two u-joints on each end of the shaft. They did it for
ride
> comfort to the Master in the back!
>
> Bruce A. Whiting
>
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