4 Spd Jerico w/ '99 Motor
#26
Senior Member
iTrader: (1)
Join Date: Jan 2011
Location: Chattanooga, Tn
Posts: 1,234
Total Cats: 283
I just put one and one together. I had a spare gear box with me at Nationals. I wish I had known you all broke. We could have swapped the gearbox out in a couple hours on the Wooten's lift.
#28
And I would use safety wire and zip ties, duct tape is for barbarians.
#33
Elite Member
iTrader: (9)
Join Date: Jun 2006
Location: Chesterfield, NJ
Posts: 6,893
Total Cats: 399
With my T5 swap, I bolted the PPF to the new transmission cross member. I assume something simple like that would work with a Jerico.
This is an old picture but you get the idea. Now I have the mount on the back side of the crossmember which gives me more room to adjust pinion angle, and there's some urethane foam spacers (hacked up NB front spring stopper) between the PFF & crossmember instead of being rigidly mounted.
You will need an accurately balanced driveshaft...the PPF does buzzzzzzzzzz like a giant tuning fork.
This is an old picture but you get the idea. Now I have the mount on the back side of the crossmember which gives me more room to adjust pinion angle, and there's some urethane foam spacers (hacked up NB front spring stopper) between the PFF & crossmember instead of being rigidly mounted.
You will need an accurately balanced driveshaft...the PPF does buzzzzzzzzzz like a giant tuning fork.
Last edited by TurboTim; 10-09-2013 at 01:34 PM.
#38
But you dont know how much of the rotating force the diff mounts are taking, probably almost all of it. Which is why the diff arm with the notch cracks on cars making a lot of torque. The tranny mount and not connecting the PPF to the tranny mount rather than the subframe basically turns the ppf into an overly heavy diff mount. So you'd save some weight nixing it completely and just putting a mount near the nose of the diff.
#39
Elite Member
iTrader: (9)
Join Date: Jun 2006
Location: Chesterfield, NJ
Posts: 6,893
Total Cats: 399
The way I see it, and I could be wrong, is that the miata diff housing sees 2 loads.
1. The twist from the driveshaft trying to rotate the diff housing along the direction of driveshaft rotation. That's taken up mostly by the ears. This should be the driveshaft torque divided by the distance to the ear (divided by two, cause there's two ears).
2. The pinion gear trying to climb the ring gear. that load taken up by the PPF.
I'm not confident on how to calculate #2 but both ways I can imagine it bring me around 1000lbs at the end of a 4 foot PPF pole, using 300ftlbs engine, miata first gear, and ~4:1 diff.
1. The twist from the driveshaft trying to rotate the diff housing along the direction of driveshaft rotation. That's taken up mostly by the ears. This should be the driveshaft torque divided by the distance to the ear (divided by two, cause there's two ears).
2. The pinion gear trying to climb the ring gear. that load taken up by the PPF.
I'm not confident on how to calculate #2 but both ways I can imagine it bring me around 1000lbs at the end of a 4 foot PPF pole, using 300ftlbs engine, miata first gear, and ~4:1 diff.