28 Fast Four build

[bob w]

My experience is the upper A arm has to be installed with the rear adjusted inboard almost to the end of the slot to get 2 or 3 degrees of caster with the aftermarket kits. Even less with the stock MII crossmember assembly. I first go for zero camber and then see how far I can move the rear of the A arm in.

This is especially true when I use a stock MII crossmember and spring hats installed as a single unit. No cutting it apart. With aftermarket kits the spring hat can be slid back from the crossmember, using a plumb line for vertical (with the earth, neglecting the curvature of the earth). This moves the centerline of the ball joint of the upper A arm rearward from the centerline of the lower A arm ball joint when the upper A arm is centered in the adjusting slots. More adjustment is available.

My Renault build shows the aftermarket MII installation And my Rover build shows the stock MII crossmember assembly installation.

 

[DozerII]

I've never felt so good, knowing I'm a pain in the a$$, ---- harping like that.
Keep up the good work.
Could you put the hats on the opposite sides and gain any 'front to back' advantage, or maybe the upper A frames could be swapped side to side if they are not symmetrical?

I hear ya MM, it was much easier designing my own suspension on the Essex than putting this one together. The hat will only fit on one side due to the 4 degree lean back.

Mac, MII control arms are symmetrical, left or right... uppers will swap side for side, lowers will swap side for side, at least to my knowledge.



Dozer, I think you have a problem with relation to axle centerline.

Pictures are far from geometrically correct... that said, I believe your cross member is too far back and the spring hats are too far forward...

I suspect you need to correct for "plumb", where the centerline remains constant, but the upper and lower extremities rotate on the axle centerline...

If you determine axle centerline (bird's eye view) and mark it across the horizontal flats of the frame, that's your reference mark... find ride height and hang your cross member perfectly centered and perfectly vertical (90°) to your centerline mark. Place your spring hats on that same centerline mark and you should be in the ballpark for alignment.

What I'm suggesting, is you may be working from a "squared" axle line, when you should be working from a line plumb to the world. I don't know how to explain it any better.

I surely understand your frustration. It's complicated simplicity and I'd be happy to help if I can. (Again, you know my number... )

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Thanks Doc, from measuring the A arms the uppers are symmetrical and the lowers are left and right, I'm using tubular with no strut rod.
On the top of frame I marked a front to back axle center line, that I then used a plumb line to transfer this vertically to the sides of the frame. The cross member is then centered on this line. The Horton's instructions then say to mark two lines on top of the frame one 4 inches in front of the center and one 3 inches behind these are the starting points for setting the towers. I think this part of the problem. After spending another three hours moving things around the axle center line I have positive caster but even with the upper arm set all the way in in the slots I still have -4 camber, I actually have to remove the bolts and hang the arms on the inside edge of the tower to get + camber[S

Doc I will give you a call later today.

My experience is the upper A arm has to be installed with the rear adjusted inboard almost to the end of the slot to get 2 or 3 degrees of caster with the aftermarket kits. Even less with the stock MII crossmember assembly. I first go for zero camber and then see how far I can move the rear of the A arm in.

This is especially true when I use a stock MII crossmember and spring hats installed as a single unit. No cutting it apart. With aftermarket kits the spring hat can be slid back from the crossmember, using a plumb line for vertical (with the earth, neglecting the curvature of the earth). This moves the centerline of the ball joint of the upper A arm rearward from the centerline of the lower A arm ball joint when the upper A arm is centered in the adjusting slots. More adjustment is available.

My Renault build shows the aftermarket MII installation And my Rover build shows the stock MII crossmember assembly installation.

Thanks Bob I will look at your builds.

 

[Old Iron]

I was thinking it said to cut the frame notches deeper, in the upper hats, to be able to get the proper camber settings.

 

[bob w]

Yes, it doesn't look right in the area Old Iron pointed out. Usually the spring hats are more horizontal, side to side, not tilted up so much.

 

[DozerII]

I was thinking it said to cut the frame notches deeper, in the upper hats, to be able to get the proper camber settings.

Yes, it doesn't look right in the area Old Iron pointed out. Usually the spring hats are more horizontal, side to side, not tilted up so much.

Exactly what I was thinking. I am about a 1/4"too high with the towers despite using the Hortons calculations exactly. I have read a bunch of other install instructions for the 56"track width and they all say the slotted adjustment holes for the upper CA's should be 28 inches side to side to the center of the slots and on mine they are 28" to the inside edges of the plate. Here's some photos as you can see with the CA hanging iver the inside edge of the tower I'm almost bang on camber.

 

[DozerII]

Big thanks to Merc Mac, Old Iron, BobW, and Dr. C. Thursday afternoon the Good Doc and I had a great discussion on the phone, comparing notes and research. There was a member on here and the HamB, El Polaco that has a great thread on how to Mustang II suspension with all the dimensions, that both Doc and I feel is the goto for info. Not sure if we can do it but, I think we should cut and paste his thread in a "sticky" in the Suspension section.

Horton's cross member kit is very well thought out and executed, but has some not so accurate measurements in the instructions. For the stock track width (56") Hortons says the upper control arm slots have to be 28" inside edge to inside edge, and in fact should be to the center of the slots. This is the only error in the instructions but it is a big one.

As Old Iron suggested I took the spring towers back off and made the frame notches an inch deeper on both sides, Not as easy as it sounds cuz it meant adding material to the angles on the tower to give more frame contact area on the sides.

I now have alignment angles where they should be and still have room for adjustment.

 

[Torchie]

Good to see you getting things where they should be. This site is a great resource and everyone is always happy to share their knowledge.
I have followed a few of these installations even though I doubt that I will ever do one. Way to complicated for me.
Torchie

 

[bob w]

Yes, I use el Polacko's thread as a guide too. He knows what he is doing. Glad you are getting it together.

 

[Bamamav]

Good to see it's working out. I too toyed with the idea of using one, but the lack of funds kept me from it.

 

[smallfoot]

Glad to see you getting it right. These guys are tons of help![cl

 

[bob w]

Do you intend to box in the open areas of the spring towers and crossmember?

 

[Skip]

Glad you got it all sorted out. [cl



I think I'll stick to straight axles. Besides, I have a few of them.

 

[Dr Crankenstein]

Nice talking to you as always, Dozer.


If I might add a couple notes on the subject...

bob w spoke to alignment differences between factory crossmembers (one fixed piece) and aftermarket (three piece) kits.

On the same subject, Mac posed the question below...

Could you put the hats on the opposite sides and gain any 'front to back' advantage

The answer is this... factory crossmembers have the slotted (upper A-arm adjustment) holes set 1/2" back from the axle centerline... the aftermarket vendors make their spring hats with the slotted holes "on center"... apparently to save a dollar and make the inverted mirror image "work" on both sides. (Seriously?)

I asked B-tard to waddle out to his shop and take a picture to demonstrate...

The offset is obvious, isn't it? If the aftermarket vendors were to accurately replicate the MII geometry, they would make a left and right spring hat, properly offset to facilitate caster... at least that's the way I see and understand it...



Note #2: I've read and heard many MII horror stories. I've also seen a few in person. Most, I believe, are due to blind ambition, credit card ability, a reputable butcher shop and little knowledge or fact.

Among the numerous possible mistakes, some persons compromise the upper control arm's ability to hold its place... namely, they powdercoat or heavily prime/paint/clear the cross-shaft and/or the spring hat's surface. The knurling on the shaft is there for a reason! It needs its "teeth" to hold under pressure... difficult as it is for me to say it, "bareback" is best, paint later.

Soory to hijack Dozer! I could babble on and on and on, but I've said enough!



Credit to El Polacko (Industrial Chassis), my friends (Rich and Larry) and the good people here for everything I've learned and have yet to learn on this subject and many others!


.

 

[Bamamav]

One mod I saw years ago in a magazine, I want to say it was written by Pat Ganahl in Rod and Custom but might have been somewhere else, was to mount a 90 degree angle piece to the slots on the top hat. Then the bolts holding the upper control arm on were horizontal going through the angle and could be adjusted with shims instead of relying on the grip of the bolts in the slots.

To visualize it, the angle would fit like an L on top of the hat, with the bolts horizontal like the arms. The L piece would have to have the vertical leg located as far away from the tire as possible to have full adjustment possible, just like having the bolt at the far end of it's inner travel in the slot.

Now, you might say this would put undue stress on the mounting bolts, not so, it shouldn't be anymore force than what is on the bolt heads when mounted in the factory position. Lots of A arm suspensions mount the upper A arm in this manner, you are only talking about maybe 1" total space between the arm and bracket and that area is filled with shims. Might not even be that much, maybe closer to 1/2".

 

[DozerII]

Do you intend to box in the open areas of the spring towers and crossmember?

Yes I will be boxing in all the open areas as well as a couple other modifications.

Thanks again to everyone for all the great advice,

No Hijack here Doc just great info. If there had still been an issue with obtaining enough caster I would have made new top plates and move the slots rearward as you described.

Bamamav there are a few Mustang II kits out there that have designed the upper a arms to mount just the way you described.

 

[bob w]

This hobby wouldn't be near as fun if you didn't have to think, plan, fabricate and modify. Boring if you just bolted kit parts together.

I love the Fast Four. You'll have a heck of a hot rod when done.

 

[DozerII]

This hobby wouldn't be near as fun if you didn't have to think, plan, fabricate and modify. Boring if you just bolted kit parts together.

I love the Fast Four. You'll have a heck of a hot rod when done.

Isn't that the truth Bob, and thanks.

 

[DozerII]

Some more progress Another suggestion by El Polaco that the Doc and I discussed was the rear lower control arm mounts. All the kits for tubular control arms are supplied with a thick bushing material and gusset to be welded to the rear of the cross member. This puts all the braking and pot hole torque on the cross member setting it up for failure.

The recommendation is to install a separate pair of frame brackets for the rear of the control arm putting it in double shear and taking a whole lot of torque of the cross member, so that is what I have done.

 

[Torchie]

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Torchie

 

[Dr Crankenstein]

Lookin' good!

I like your air springs, can't even see them!

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