I.f.s.-i.r.s.

[Bruce R]

Guess I posted at the wrong spot. Anybody out there got any experience with the Crown Vic. front suspension swaps they talk about on FastnLoud ? Also the I.R.S. from the later T-Birds, anyone mess with those ?? I'm conspiring to go full independent with my 55 Mercury.

 

[Blue Eyed Devil]

CV would be too wide for that car. Even if it wasn't, the track width would be WAY off from front to rear.

 

[Bruce R]

I.f.s./i.r.s.

CV would be too wide for that car. Even if it wasn't, the track width would be WAY off from front to rear.

Ok, ain't found a CV to measure yet , I figured I'd have to section the crossmember but I know there's alot more to it than that. I can buy dropped spindles and disc brakes for the stock suspension, but do you know a good way to get power steering into it ? ( other than stock 1955)

 

[Blue Eyed Devil]

Sectioning isn't really possible on the CV, as it is a bulky one-piece aluminum unit. If you're wanting updated suspension and power steering you may as well go with a MII that is pre-engineered for your car. A donor clip is another option, but by the time that is all sorted out and rebuilt you would again be far ahead with the MII.

 

[Bruce R]

IRSk

Sectioning isn't really possible on the CV, as it is a bulky one-piece aluminum unit. If you're wanting updated suspension and power steering you may as well go with a MII that is pre-engineered for your car. A donor clip is another option, but by the time that is all sorted out and rebuilt you would again be far ahead with the MII.

I priced the mustang units, more than what I paid for the car ! I'm not one to solve problems by throwing money at them. The way I see it, I should be able to upgrade my steering and front suspension for about 100 bucks and a bunch of work on my part.

 

[Bamamav]

From what I've been able to find online, your Merc is 57 1/2" hub to hub. 90's Crown Vic with the aluminum crossmember is 67 1/2" hub to hub. 84-87 Corvette is 59 1/2" hub to hub. Jag XJ is 58 1/2" hub to hub, but may vary between 6 and 12 cylinder cars.

So, no direct fit IFS from a donor. You might narrow one, but then you get into trouble finding a narrow enough rack. Somebody, I think it was Animal, narrowed a Camaro or Nova front sub frame to fit his 55 Ford. DJ also did something on his wagon, I'd have to hunt up his build thread to see what he used.

 

[Sam_Fear]

I think the G-body is a little narrower than the Vette. You really need to make sure what your width is now. If you can find something a little narrower, it's easier to bump your wheels out with spacers/adapters or wider rims, rather than cut a cross-member.

 

[Flipper_1938]

Jag XJ is 58 1/2" hub to hub, but may vary between 6 and 12 cylinder cars.

6 and 12s are the same width, but v12 rears have a posi unit in them.

Toyota supra and Lexus sc400 might be something to look at. Both have ifs and irs subs under them...not sure on width.

 

[Bruce R]

IFS

Well, at the very least, I can get front disc brakes by using Granada spindles and then figure out what power rack I can put in., I guess the original suspension isn't really a bad design, I suppose I could find a disc brake rear and just keep the leaf springs ??

 

[Blue Eyed Devil]

I priced the mustang units, more than what I paid for the car ! I'm not one to solve problems by throwing money at them. The way I see it, I should be able to upgrade my steering and front suspension for about 100 bucks and a bunch of work on my part.

Brakes, steering and suspension aren't an area to be dismissed as "throwing money at them". Regardless of where you source it, you're going to have some bucks in a proper and safe setup. Junkyard parts are great, but they need money to be rendered serviceable as well. I'm all for being thrifty, but the fact is 100 bucks doesn't get you far anymore. One replacement disc for a Granada is 50 bucks, so the math isn't hard to figure out. Used parts all still need refurbished. That's if and when you find one in a junkyard, dig it out, clean it up, figure out if it is even serviceable or not, and then start "throwing money at it" with rebuild parts. Your car - your choice to be made, I was just offering an alternative. Best of luck.

 

[TIMOTHALE]

rear end swap

I would guess that a 57 and up 9 in should be a bolt in then an easy disc swap using ford later year parts.

 

[Bruce R]

IFS

Brakes, steering and suspension aren't an area to be dismissed as "throwing money at them". Regardless of where you source it, you're going to have some bucks in a proper and safe setup. Junkyard parts are great, but they need money to be rendered serviceable as well. I'm all for being thrifty, but the fact is 100 bucks doesn't get you far anymore. One replacement disc for a Granada is 50 bucks, so the math isn't hard to figure out. Used parts all still need refurbished. That's if and when you find one in a junkyard, dig it out, clean it up, figure out if it is even serviceable or not, and then start "throwing money at it" with rebuild parts. Your car - your choice to be made, I was just offering an alternative. Best of luck.

I do get where you're coming from Devil, I don't do anything half assed. I have an " in " at the local boneyards, they call me when they need some quick welding or machine shop work, so my parts are usually free. I'm just always looking for alternatives, I've even considered dropping the Merc. body onto a modern chassis, such as a Dakota pickup or something on that order.

 

[Blue Eyed Devil]

I do get where you're coming from Devil, I don't do anything half assed. I have an " in " at the local boneyards, they call me when they need some quick welding or machine shop work, so my parts are usually free. I'm just always looking for alternatives, I've even considered dropping the Merc. body onto a modern chassis, such as a Dakota pickup or something on that order.

Understand that, I was just saying the bill at the parts store for rebuild components generally exceeds the bill at the boneyard, even if it is free. Regardless, the barter system works well. While I would HIGHLY advise against a full frame swap, the Dakota front clip would work decent on that car. Track width is close, disc brakes, and power rack & pinion that is in in a non-obtrusive location. While it isn't the 5"BC of the Merc, it is 4.5", which keeps it Ford-friendly. Going back to the frame swap - Not worth hacking up the floor and every body mounting point on the car to stick with what is essentially the same type of chassis. Leave the firewall back and just mount the clip, that way the only thing to be reworked are core support, fenders, etc.

 

[Bruce R]

IFS

Understand that, I was just saying the bill at the parts store for rebuild components generally exceeds the bill at the boneyard, even if it is free. Regardless, the barter system works well. While I would HIGHLY advise against a full frame swap, the Dakota front clip would work decent on that car. Track width is close, disc brakes, and power rack & pinion that is in in a non-obtrusive location. While it isn't the 5"BC of the Merc, it is 4.5", which keeps it Ford-friendly. Going back to the frame swap - Not worth hacking up the floor and every body mounting point on the car to stick with what is essentially the same type of chassis. Leave the firewall back and just mount the clip, that way the only thing to be reworked are core support, fenders, etc.

Any particular year Dakota ?

 

[Blue Eyed Devil]

Any particular year Dakota ?

1st gen - '96 and down.

 

[Torch]

I was considering something like this Jeep grand cherokee ps box swap kit for my 51 merc
a long time ago some desperate folk used the bulky 70's f150 2 wheel drive PS box but those things are huge

http://shoebox-central.com/49-51-mercury-power-steering-conversion-kit

 

[Torch]

I can't remember which car i was researching...
I have a 51 merc sedan and a 57 ford 300 custom.
one of them I can use a faster ratio mustang manual steering box.

reading up I learned the ford shoeboxes had a bump steer issue with the stock steering but mercury had corrected that by 1950 and the 1950 and up merc factory steering is supposed to be setup just right.
Ive seen a couple where the guy kept the stock merc suspension but had tubular control arms built allowing him to use ballpoints instead of kingpins and trunions.

There is also a 50 merc featured in one of the car mags where he created a nascar front suspension for it using surplus nascar parts.
nascar setup is derived from the old galaxy suspension but is converted to front linkages and a sagninaw front mounted steering box

This is the car. I have the hotrod issue somewhere
I don't need to dig it out it has the usual circle track galaxie style setup
these suspension pictures are NOT of this car merely like what is in this car.

 

[Torch]

leaf sprung rear suspension is pretty much solid science
most of any handling issues you are going to have are related to your front suspension

looking at the side of the car flat springs will have more side to side roll as the active roll center (line drawn rear eye through front eye) of the rear suspension is going to be parallel to the roll center of the car
tipping the front of the springs down takes the active roll center out of alignment with the car's roll center
so when the car tries to roll the geometry of the rear suspension fights it
roll center is also a consideration in how a 4 arm ifs is setup

the front suspension design determines the roll center of the car... how high or low it is
which is why the 2nd generation F body suspension carried the nickname "hung" like in a swing
the roll center of the car was higher than the fore to aft center of gravity and the car hung" in it's suspension like a swing
the opposite case would be if the roll center was below the center of gravity the car would feel topsy turvey like it wanted to lay over in a turn

Another thing to consider with leaf springs
looking down from the top (or up from the bottom)
the axle is going to shift towards the shackle in compression as the spring flattens out under load.

-in a right turn
the left side of the car goes down
the left side of the axle shifts rearward causing the rear of the car to want to steer itself left slightly resulting in a feel of a slight amount of overseer
So if the front suspension is designed with a slight amount of understeer under the same compression this will cancel out the rear and the car will feel balanced but merely drift slightly outward in the turn but in a balanced way.
when you come out of the corner and the suspension decompresses the car will shift slightly right and the steering feel will tighten up
This is how 2nd generation F bodies are setup and why they handle so naturally sweet.
I think that design was the pinnacle of suspension design for GM.


Anti-dive
If your upper a arms are flat (looking from the side) brake action will have no input into suspension loading other than a result of the weight shift of the car itself
But if you tip the back of the A arms downward like on the 2nd gen F body...
the torque of the brake trying to rotate the spindle causes an active downforce on the upper a arm pushing the front tires harder against the ground or in other words trying to lift the front of the car
If the A arm is NOT tilted at the rear this torque merely tries to push the a arm foreward.

there's something about having the rearsprings closer at the front than at the rear but I can't remember why.
it's not essential it's just some sort of advantage.

If you draw a line through the mcenter of mass of the car
and draw lines through all the pivot points
by comparing the angles of those lines you can see how the mass of the car is going to react under load as it can only move through the axis of those pivot points

 

[Torch]

I might have been a little off on my description
here are some sources to review

http://www.joesracing.com/rt-4179-roll-center-magic.html

https://balancemotorsport.co.uk/suspension-geometry

http://www.motoiq.com/MagazineArtic...in-the-Geometry-Part-One-The-Roll-Center.aspx

http://www.racingaspirations.com/suspension-jacking-forces/

 

[Torch]

It's preferable to counter poor handling with improved geometry than through increasing spring rates and thicker sway bars
the latter interfere with the tire's ability to stay stuck to the road. the stiffer the springs past what is necessary to keep the tires planted....the more the tires will want to hop over track irregularities thus losing traction.
if you welded the axles to the frame you'd have perfect geometry and zero articulation