The engine and tranny are installed in the frame at a 4 degree angle,
the front is higher than the back of course. So, the pinion should be
pointing up about 2 or 3 degrees at the front, relative to the frame.
This assumes you put the new engine/tranny at 4 degrees, as original.
One way to make sure you do this, is to get the frame sitting level
front to back (use jackstands to hold it up, and shim if needed). Then,
the engine should have the carburetor mouting flange and transmission
pan both be level...as these surfaces are machined by the factory at the
4 degree angle.
The "12 degree" angle is the angle from the original spring perches to
the pinion centerline, by the way. When you start changing things
around, you really need to ignore the 12 degree angle...and worry about
the actual angle of the pinion relative to the engine/tranny centerline.
The rearend yoke can be changed, if you have an extra 8.5" 10 bolt yoke
for a normal ujoint laying around (what, you mean you don't?). You
could probably find a yoke at a junkyard or rear axle shop. However,
the nut that holds on the yoke also sets the pinion bearing
preload....so you have to be careful to tighten it tight enough, but not
so tight that you crush the crush sleeve any more than it already is.
You need to rig up a strong flat or angled bar with some holes in it to
bolt to the yoke, using the ujoint strap holes, then torque the nut down
to specs (usually the minimum torque is around 125+ foot pounds). But,
before you actually get it this tight, you need to get a good feel for
how much drag is on the pinion bearings....because you don't want to add
more than about 10 INCH pounds of drag when you tighten the nut. If the
pinion gets hard to turn by hand (without using the bar), then you are
getting the preload too high...the cure is to disassemble the rearend,
and replace the crush sleeve, and reset the pinion bearing preload,
which is not a fun job.
You could also just use the Seville driveshaft, or at least the rear
constant velocity (double u-) joint from it. This is a good way to cut
driveline vibrations if you don't get the angle exactly right. You will
have to deal with a driveshaft shop, and also you will have to see if
the shaft is long enough. The constant velocity joints do wear out
where the two halves meet, there is a little pilot bushing in there.
THe driveshaft shop should be able to help you out on this.
I prefer the crossmember type front motor mount setup when using the
stock suspension, but with a mustang II suspension, I'd go for the weld
in side mounts. The mustang crossmember will strengthen the frame up
there enough to support the added twising on the frame rails.
J & M Street wrote:
> Thanks Jim!! That's exactly want I needed to know. I have a set of rear
> monoleafs I plan to use. (w/ must.II front end) I read an article that said
> if the truck is lowered, the angle should slightly less than 12 degrees. My
> problem is the engine and tranny aren't in yet to measure off of, what do
> you think a ballpark angle estimate should be? 10 degrees maybe? The yoke of
> the rear end is round and the drive shaft end is a double u-joint carrier
> thingy. Do you suppose having 2 u-joints on the one end would help
> compensate for any mis-alignment, or should I trash that and go with a
> single u-joint drive shaft?
> I don't mean to bombard you with questions, but you are the first guy that
> seems to know exactly what I'm dealing with, this is my first attempt at a
> project of this magnitude and I really need the input so I can get it right
> the first time. Thanks alot for any suggestions. (now I need to figure out
> which type small block motor mounts to get, bolt in or weld in?) Thanks
> again, Jeff Street
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