Tell me about... Lowering block and suspension geometry

[corpse]

Well, I'm back at it again.. The weather is nice and I can open the garage and work on the car and enjoy it.

A couple months back I installed some standard eye 5 leafs, and realized it needed to be lowered. So today, I put some 1.5" wood blocks on the leafs and bolted it down to check the height, and I'm happy with the stance. The rearend is now .9" higher (Approx ) higher than the front, which I think gives it a great stance (the front is also lowered)..

To my question.. With the rearend and having lowering blocks that size, what does that do with the roll center and suspension geometry. Since I've got a bunch more work to do, if I need to replace the new leafs, now is the time to do while it's easy Is it worth it, at this point, to get mid or reverse eye and avoid using 1.5" blocks?

 

[brianj5600]

This may help. http://web.archive.org/web/20041126011147/http://www.rpmnet.com/techart/leaf.shtml

 

[HistoricMustang]

This may help. http://web.archive.org/web/20041126011147/http://www.rpmnet.com/techart/leaf.shtml

Very good information...........

HistoricMustang
www.historicmustang.com

 

[corpse]

yeah, excellent reading materials for my morning coffee - well, for ME while I drink my morning coffee... After I read it a couple times ,we'll see what new questions I have.

 

[corpse]

ok, I did some reading - it was worth it, although still more questions, of a different nature now

Everything in the article was geared towards a normal statically mounted mount, where the rearend torque would cause the leaf spring to load/unload/twist. the setup I am leaning towards, it using a floater (as seen here). I say leaning towards, only because I'm not sure which will be the best for me

It seems some nice traction bar, like cal-tracs, which certainly work from axle torque, pushing the rearend down (or chassic upwards). But it would seem a limiting factor, is the binding of the leaf, no? Having the rear float OTH, it would seem to allow a lift bar to push down on the rearend with less restriction. (The lift bar would be mounted like the TCP setup, coming off the rearend with the pivot point on the x-brace - which places the pivot point ~ 15" towards the front of the car from where the front of the leafs pivot, which means more leverage, right? Here's a pic of their torque arm setup, same concept of what I'm thinkin tcp torque arm

On roll center (to keep with the original topic <g>)
As you can see in the first picture, by drawing the datum line between leaf spring mounts, with the lowering blocks in place, does that mean the roll center is moved downward, since the chassic is being lowered, or is the roll center raised due ot the lowering blocks...
ah, nevermind, the answer to my question.. good to reread that document again.

If lowering blocks drop either or both spring eye positions relative to the axle then the rear roll center height will be lowered and chassis roll, along with rear side bite, will increase.

Also, the front leaf eye is ~ 9" off the ground, the rear leaf eye is 14". Here's a pic of the rear shackle angle I should have taken a better straight on pic to illustrate it better, but as you can see, its a stock setup there - all rubber as well.

 

[Hack]

What are your plans and goals for the car? Do you just want it to look really cool, or are you going to race it somewhere?

 

[HistoricMustang]

What are your plans and goals for the car? Do you just want it to look really cool, or are you going to race it somewhere?

Yes, are you going to do the straight line performance stuff, some round and round track laps or just want street performance?

HistoricMustang
www.historicmustang.com

 

[corpse]

I want all around performance, but in a "corpse" kinda way... Think of a viper or something.. My goal is fun, but I'm into excessive fun... Not like a turbo 4-cylinder fun, but crap in your pants fun. I don't want to be #1 at the dragstrip, but want to rip it up at hte dragstrip one day, go camping the next day, then drive to a 2 1/2 mile road track the next day. And look at my pic on my site and my sig, I'm not all about 1/4 mile - I want to handle the turns, and do it with groceries in the trunk Afterall, there MUST be a better way to make a milk shake