So, im chasing a nasty speed related vibration in the duster. In addition, im changing rear springs to do away with the angled four inch lowering blocks.
Anyway, im doing it all on the floor. Probably because im a masochistic person.
The rear of the car is up on stands, front is not.
Im second guessing wether i can check pinion angle this way. Part of me says i can, as the important part is the relative angles, not the absolute angles. Other part says that tjis is a recipe for error and wasted time.
So, CAN pinion angle be checked with the car like this?
I'd check it with the rear suspension carrying weight, but jack stands under the rear axle vs on the ground (or all 4 lifted) won't matter.
In reply to rslifkin :
Rear suspension is compressed with the floor jack in this picture to check rough ride height of the rear wheels in the wheelwell. Id use actual stands for real, under the axle. Don't feel like dropping this car on me.
Ok. As long as the rear axle and trans are in their correct relative positions, your measurements will come out fine.
Cribbage blocks. Problem solved
RossD
MegaDork
12/7/20 1:47 p.m.
In reply to RossD :
Man! Thats an AWESOME link! Definitely will be used soon....
This vibration is almost certainly either pinion angle or damage to wheels/tires. However, they balanced ok and didn't look wierd, so pinion angle is more likely
Plus another for checking at ride height, not in hover mode. Are you telling me that you only have one set of wheels for this thing so you can't rule out a wheel/tire issue?
In reply to ¯\_(ツ)_/¯ :
I have two sets of wheels, but only one with tires.....
And im trying to get rough idea before bolting it all back together. Im sure it won't be exact, but it would be nice to know if im in shim range or welder range.....
In reply to Dusterbd13-michael (Forum Supporter) :
If the rear suspension is where it would be (relative to the rest of the car) if the car were sitting on the ground then you should be good, I thought it would be simpler to set it down but I guess it's more disassembled than I thought from the picture.
As a result: currently, pinion is bang on the equal but opposite spec!
Well see what its like on the ground and lift, but its already way better.
In reply to Dusterbd13-michael (Forum Supporter) :
So are you implying that the lowering blocks threw your pinion angle out of whack?
In reply to Woody (Forum Supportum) :
Yes-ish. The combination of custom built leaf springs with a ludicrous amount of spring Arch and the lowering blocks created a pinion angle mismatch that caused the vibration. I've removed the lowering blocks, and rebuilt the spring pack into something more normal to eliminate the need for lowering blocks. Or at least that's my working Theory at the moment.
My '77 Silverado did not like equal and opposite.
I'm currently at engine down \ 4.5°, driveshaft down \ 1.8°, and pinion nose up at \ 0.5°
With the pinion at 3° nose up, there was nasty vibrations on any and all even slight acceleration, like driving up a shallow hill. Nasty vibration around 60km/h.
With the pinion at 1.5° nose up, it cruised freaking awesome with no vibrations at speed, but nasty vibrations under acceleration. Less nasty vibration around 60km/h.
Currently a slow cyclical vibration, faint vibration around 60km/h.
I may still try nose down next. I did try that a year or so ago, but don't remember what the result was.
