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Discussion in 'Transmission & Driveline Topics' started by ULTM8Z, Dec 1, 2019.
Problem is most of these higher rate springs also lower the car which I'm not interested in doing.
The set I got from Keith was clamped pretty well on the front half of the spring...no wheel hop for me either.
Landrum makes 2 styles, a 5" and 6" true arch. The 5" is like a "typical" 1.5" drop leaf, the 6" is closer to "stock" but it does not have the soft 125# or less rate so it does not behave like a wet noodle under the ass end and squatting every time you hit the throttle.
They (Landrum) do not sell on "drop" for the "looks", this is a serious racing spring that works on the actual weight of the car and what you need it to do.
Think Custom works rears are 175#. They come with an adjustable rear shackle, I’m in lowest setting . Tire center is 14.5 to fender lip in rear.
Thanks for the info. I'm going to go one step at a time here...
Right now, the car rides and drives exactly the way I want it.
When I'm driving normally, it's actually a very pleasant car to drive (yes, I said "pleasant"... I'm pushing 50 years old, ok? ).... ride quality, exhaust nose, no squeaks/rattles, etc. But at the same time, when I get on the throttle I still get that rowdy muscle car feel.
The ride and drive is so dialed in that I'm very hesitant to change anything driveability-wise that I absolutely don't have to, like spring rates.
Nice thing is the Landrums come in 25# increments from 150-250#.
If you do your research, you may find that some of the "other" top companies that sell leaf springs look like to be the same blue colour. mmm
He offers several rates, mine are 200# springs
Ok, so I think I'm back to my earlier theory about the GV hitting the body.
I went under the car to see the lateral alignment of the driveshaft (took some measurements between output shaft centerline and the subframe as well as against the pinion) and it seemed I was off a little to one side, so I loosened the bolts between the trans mount and the crossmember and moved it over over a little.
I was using a small pry bar to move the tailhousing over and started looking at how the tail housing moved with the stock rubber trans mount tight. Holy cow, that thing moves A LOT. And because the GV is so far back of the factory mount, small movements at the mount itself translate into very large movements at the GV unit. The rubber mount is so soft I could actually take the pry bar and move the GV over so much that it hits the tunnel.
Any rate, after moving it over, I took it out for a drive and lo and behold, even with lighter throttle it'll generate the vibration now, only more severely. And the frequency of the "slapping" matches exactly what I was noticing before. So my original theory seems to make more sense now, as opposed to it being driveline angles and axle wrap.
One thing that wasn't adding up in my head (as I mentoned earlier on) was that the vibration frequency wasn't anywhere near what I would expect for such a slow driveshaft speed coming off the line.
Any rate, while it's good I got the driveline angles corrected (and I REALLY appreciate everyone's time and input in educating me on that stuff in this thread), I'm going to try to focus my efforts on sorting this out rather than the driveshaft/pinion angles. Probably get a poly mount and see if that eliminates the issue.
Progress! That is good. Poly mounts are great. When I installed poly motor and trans mounts, my 4 speed shifter totally stopped moving in the console when on/off throttle. With rubber mounts it was flopping around like crazy.
Did your measurements indicate that it was shifted to the passenger side about 1/2", I will assume that you moved it over to the driver side to gain clearance.
If so, you have now changed the engine/trans center line out of alignment, and is now NOT parallel with the rear end as viewed from the top. These cars had a 1/2" engine/trans offset to the passenger side, if that's the case, you have added to the issue.