Front end geometry help needed (new pics added 7/28)

If you look at the first 2 pics in Post #49, the rack ball&socket, relative to the lower A arm's inner bushing looks offset, to the driver's side. Originally El Polacko mentioned about using a rack extension. The whole rack appears at least to be offset, which would introduce bumpster as it then would not mimic the A arm movements.

 

Easy to see with the wheel off. In the last photo the pivot point of the upper control arm is designed to be below or level with the balljoint attachment - look at the ball joint cup, that should be parallel with the spindle. So the whole upper attachment (spring, contol arm & shock) are too high. Is that a preassembled/welded unit from fatman or does he provide the brackets as a kit and you just weld it like wherever?
I'd be inclined to lower the top, biggest nuisance would be getting the upper control arm attachment point ackerman angle correct. To do that you'll have to get to bare frame rail like Steve said.
I have one of those trucks right now in the shop, i rebuilt the twin ibeam and just now finishing the doors, window tracks etc. The owner is coming tomorrow and he keeps talking about putting a fatman under it. Hmmm
That does look like silicon - a very bad sign.
Keep us posted

 

With no weight it looks like the ride position, level parrrel to ground.If you remove the shock it should drop down.Was this a fatman kit.These are fearly new kits for 66 pu.Anyway I would down the top down,would be the lesser of work.You will have to cut into frame.I had a 56pu but think 66 has thicker frame.

 

Well I've been looking this over and it looks like if I do decide to drop the top, the spring hats have about 1.5 inches of verticle built into the rear and about 2 inches built into the front. Why couldn't I just trim that to get my 1.5 inches instead of cutting into the frame? The sixth pic in post 49 shows what I'm talking about.

 

you may not have the clearance under the rear of the upper control arm bushing before it would hit the frame. Also you need clearance for your attachment bolts on top of the frame. IF the spring pocket is over 2" tall you may be able to do this.

 

I'm finding that heated coil spring interesting. I assume since it says Fatman on it it came with the kit. He must of included extra tall springs to compensate for raising the hat 2" but not shocks. My guess before the spring was heated the shock sat at full extention at ride hight and someone heated it to get some up travel on the shock to improve the ride.
I find it sad that a company would sell such a poorly engineered kit with improper parts (springs in this case) to cover up the real issues.

 

WHOA!!!!! Crown Vic idea new to me, is this like Volare/Aspen package?, got pics? TIA!!!

 

Tons out there, for a little googling:

http://www.ford-trucks.com/forums/716058-buildup-06-crown-vic-front-suspension-into-67-f100.html

http://www.jalopyjournal.com/forum/showthread.php?t=255247

http://www.youtube.com/watch?v=PTXrTGhgX0g

Keep an eye on the wheel offset issues; you need to be able to run something approximating the OE CV wheel offset to keep the steering scrub radius correct.

 

I have used several of there setups and they have worked fine.......read what 69SuperCJ said in his first post..... not sure if this is fatmans setup or not....... Isn't someone from fatmans on the hamb....?

 

Elpolacko, dont you make a crossmember kit for 57 to 65 Ford PU's?

 

Sure looks to be constructed just like every other Fatman kit I have seen since they started business. With the same issues I have been concerned about since they started.

I used to do the Dodge Dakota based IFS kits. I am researching and compiling for the reintroduction to the market. And waiting for a market to sell them in

 

I have to ask a few questions.Did you drive this truck and about how many mile total.What did it drive like.
I have taken a few measurement on mine and from the pivets upper to lower on the "back side" its about 10"
Before you go cutting it up.
First thing i would do is get new shocks and v8 springs,put it back to together and take it from there.To me when it was done someone wanted it realy low.If the new springs lift it as it should you can always get 2inch drop spindles and would keep the same height as you have now.You have to take it apart anyway and need new springs.

 

George, maybe you missed this:

I really don't think he has a bumpsteer problem. I am sure there is some present but it is the least of his concerns.

I know you are just trying to help but you are barking up the wrong tree. Look at the tire wear man! Classic negative camber, high negative camber causes twitchyness.

Are you measuring from the center of the upper cross shaft to the lower pivot? Because that's not how we are measuring this. If he were to measure from pivot to pivot the dimension would be greater than 10".

V8 springs? Do you know what value springs are in there now? Are you sure these are shorter or of a lower spring rate than this V8 spring you want him to install?

Check this out.

If you are talking about 1974-1978 Mustang II front springs you have about four choices of stock replacement springs.

That information is taken directly from my TRW spring book. Goes to show you those little economy four cylinders were heavy little bastards because they took a heavier rate AND a taller spring!

 

I just don,t like the looks of those springs.They have been heated.IF the shock was removed the frame would drop, maybe spring would be in mid air.I did look at Speeway springs the 1800lbs is the stiffest,and they are about 13.5 inches long.
If a longer spring were used it would have to raise the a frame.The only thing I don,t have is the inside pocket of the srping if 10 inches thats would be 3.5 of tension.And for the shocks MII if anything maybe to short,but i don,t think so.
AS for bump steer what is that.
My idea of bump steer is when going over bumps if one tie rod end from pivit to end is longer on one side then other,i wants to go in another direction. "What is bump Steer"
Only trying to help with the less hack job.

 

I can tell I'm not getting through to you.

Here is a mental exercise, if this front end requires a taller spring and shock than a stock Mustang II as you are trying to assert, then wouldn't it be a natural to assume that the distance between the upper spring pocket (control arm and shock mount also) has been raised above the lower control arm and rack mounts beyond a serviceable distance?

Regardless of how long the spring and shock is, the geometry is FUBAR and to install a taller spring and shock is not going to fix his geometry. It will only alter his ride height.

What is the spring rate?

If you don't know what spring rate and free lengths of the current installed springs and the springs you are recommending you are just making wild guesses. You really need to know spring rate, free length and installed height before you can start making suggestions like this.

This is a moot argument anyway, I'm sorry I even got involved.

I am not going to encourage this guy go out and spend money on parts just to test a theory. I know for a fact that the geometry of the crossmember as it's installed is causing his driving issues and not the ride height.

 

Set the suspension at normal ride height with the wheels pointed straight ahead.

Now move the wheel up and down through its travel.

If the wheel turns left or right while moving up and down through its range, that's bumpsteer.

Most suspensions have some bumpsteer somewhere but you want to minimize it in the middle range of travel.

 

Unquestionably so, unless someone changed the upper spring seat to UCA pivot relationship which isn't the case here.

In this case, it's pretty clear the UCA/LCA geometry relationship is FU(probably)BAR. It somewhat resembles those '60s sidewall-scrubber GM B/C-car suspensions that produced positive camber change with body roll.

 

TCI did one and may still offer it, they since have pulled the pictures. It had a step that dropped the spring pocket and shock down about an inch to fit the upper arm over the 5" tall frame rail and still use a stock length MII shock.

Still think it sucks.

I have dealt with this situation on other vehicles and when manufacturers do things like this for installation convenience it really detracts from the driving experience. It makes an otherwise nice driving front end feel old!

 

I think its common rule to have lower a frame even with ground.
They are there now hanging there.Now if you can get 1 deg caster and o degs camber in the slots that are there it should be ok.The shocks realy don,t do any thing for height only when hanging.The 1800 lbs spring is 425 lbs,1500 350lbs.
You are correct it will bring a frame level. Thats the goal.
Note a good spring compresser is nessary.
I,m out of here car show tonight.

 

Something like that still leaves you with the UCA in the wrong position relative to the LCA, right?

I was thinking the other way 'round - relocating the UCA mounts further down the frame to get the camber-change curve right, then cutting the upper spring perch out of the UCA mount, running coilovers with a fabricated mount at the proper height.

 

Parallel to the ground at normal ride height.

The pic IIRC shows the LCAs horizontal at full droop with the wheels off the ground.

You need 2in droop travel (maybe more) at the wheel from normal ride height to full droop. So with any sort of reasonable spring rate when this vehicle's back on its wheels the inner pivots are going to be ~1.5-2in lower than the ball joint, which is wrong.

But even if you raise the ride height with longer springs and shocks the UCA angle's still wrong and the more you raise the ride height (to fix the LCA angle) the worse the UCA gets.

In that configuration as the UCA pivots up the lower ball joint moves inward, but as the down-sloped UCA pivots up its ball joint moves outward, so if your static camber setting is ~0 you end up with substantial +camber under compression and probably some bumpsteer as well.

 

Only amongst hotrodders.

The rest of the world that enjoys good handling cars typically have the lower control arms up at the crossmember.



Stock Mustang II also has control arm angles that look similar to this. Just not as aggressive.

You remind me of a former employer who's favorite engineering quote was "you can get away with that". Sure, you could get an alignment in that position but I would assuredly handle like crap and I seriously doubt any of the OP's original concerns would go away.

A spring compressor on a Mustang II suspension should be a neat trick. External compressor maybe but internal, forget it.

Alright, here is some more data to chew on.

Stock 65-70 Ford F150 springs: common to most V8 trucks was the CS8228 or CC808. I am missing information on the CS8228.

The CC808 is 11.5" installed/1730 loaded weight/407 lb/in/15.75" free length

If we are to assume the 50% rule on spring rates regarding independent suspensions we can assume that the weight on the front end is close to the loaded weight of the truck, 1730 pounds. That would mean we need a spring that holds similar on this situation, you are reporting the Speedway spring has a spring rate of 425 and a free length of 13.5 meaning slightly over 4" of travel to hold the weight and a half inch short of where it is now at full extension.

And that is assuming quite a lot.

Shock is still wrong, geometry is still FUBAR. Nothing gained except the ride height.

That is a decent approach. I just don't know if the guy wants to go through the trouble or wants to buy a set of coil overs and control arms to go with them.

I have done similar, also notice the location of the coil over mockup on the lower control arm. Makes for a much more effective shock. And we can run a lighter weight spring.

 

Good luck driving with 1 degree of Caster.

 

When in doubt, cut it out.

That goofy set up needs a taller spindle to get the
Instant center where it belongs. AND longer shocks, and ....

 

its a bolt in swap minimal welding
http://www.fordification.com/forum/viewtopic.php?f=5&t=47610

 

Lower arm parallel to the ground is a general rule that will at least get you in the ballpark. However, some suspensions are designed with geometry that is different. In those cases the lower arm will usually be lower on the outside than at the frame.

 

Again thanks to all those who have weighed in on this topic, its definately led to a lot of good discussions and info and different ideas being floated around. As for the CV frontend, I dont want to go that route as was mentioned earlier in another post due to track width issues/wheel offset ect. It looks to me like my only alternative is to cut it out and relocate it where it should be and buy some new springs and shocks while I'm at it. I'm also going to work over the P/S pump setup while I'm at it as well.

 

Agreed, the Crown Vic front ends are extremely wide from wheel mounting surface to wheel mounting surface. That is one of the issues that the gent who built the one with the four cyl diesel ran into in the thread that has had it's link posted once or twice in this thread.

The thing (in as simple of terms as I can make it) that Elpolaco has so aptly attempted across is that the horizontal line between the top of the spring hats and the horizontal line between the center of the lower control arm bolts is several inches more than on a stock MII front end and "that" is what is throwing the front end off.

Here is a photo of a stock 76 Mustang II front crossmember that is out in one of my piles of stuff.


1. The distance between the center of the upper A arm shaft and the lower control arm bolts and distance between the center (ball) of the ball joints appears to be very close to the same on the stock crossmember but the one on the pickup has 1-1/2 to 2 inches more between the upper A arm shaft and the lower control arm bolt. That in it's self acts as a stop and won't let the lower control arm drop down with the weight off it.

 

I think relative to this discussion that you could say that horizontal at normal ride height is the lowest point at which the geometry doesn't fall apart.