Perhaps I do have brain damage (rear suspension idea)

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Perhaps I do have brain damage (rear suspension idea)

January 08, 2007, 08:47:21 PM

I'm just putting this here for the time being as it's kind of just thinking out loud, but if mods feel it needs to be relocated so be it.

First I will preface by saying this is just something that has come to me over the weekend and I'm still mulling it over, but I may persue it.

Follow along now.

Some of you know my main daily driver is an '88 Merkur Scorpio. Some of you also know it's not "normal" in that it rides on 17x8" tribars, has 12" Vette front brakes and a performance suspension. It doesn't ride like a "luxury sedan". Anyway, on the suspension. This past year I have coverted the front suspension to coil over and redid the rear suspension which included upping springs rates. Stock on a Scorpio is 100#F/250#R. Pretty soft. After my work, the rates are 275#F/900#R. No kidding this thing is stiff. However......Even though the rates are MUCH higher than stock, the ride is not all that bad. Especially in the rear. There is a bump on my way to work that will completely unsettle my Fox cars at anything over 40mph (it will launch the back of the Z-7 into the air)....but in the Scorpio...it's just a "THUMP" at 50mph.

So with this in mind the gears started turning and when I got home I pulled out the tape measure just to compare with one of my Foxes. Comparing it to my 80 XR-7 that is sitting behind it here is what I found. The track of the Scorpio with the 245's on the Tribars is with-in 1/2" of the 80 XR-7 that has the 275's on the Cobra wheels on the wider SVO/Lincoln axle. The spring locations are close, the front mounting points are close and the only thing that is really off is the width of the shock attachments. They are narrower on the Fox.

Can you hear the gears turning?

Now before you go off on the "Cobra, this" or "Cobra, that". Let me put this out here. I am replacing my current Scorpio with another less rusty twin. I will be completely stripping my existing car for spare parts and all of my mods. I will be ditching a shell. I will therefore have a complete spare Scorpio rear suspension. So no cost there.

Anyway, about the Scorpio/XR4Ti rear suspension. It is an IRS, but it is not like the Cobra or the Tbird stuff. It is a semi-trailing arm set-up that has the uprights rigidly attached to the arms. There are no upper arms. It has it's pros and cons.

Pros:

Cons:

Addressing the Cons.
The diff is an open and of odd pedigree. There are stronger LSD Euro options available, but getting them can be difficult. Guys have done 8.8 swaps, but the issue there is that route requires not only mods just to mount it, the axles/stubs have to be modded pretty heavily...and you're looking at bigger bucks. Still another option that I'm looking into is a Ford 7.5 swap. Granted it's no 8.8...but I'm not dumping the clutch at 5K on slicks.... Talking to one of the guys that have done the swap, there is still a little work, but the axle mod is pretty simple.
Different bolt pattern. The Scorpio pattern is a 5x112.4 vs the 5x 114 of the "typical" Ford pattern we are used to. On my Scorpio I just redrilled the wheels, but on this I wouldn't want to. However, I do know it is possible to machine the Scorpio hubs and then press in the Cobra/Mustang studs. The bolt circle is close enough that if you bore the hole out for the Cobra studs offset (ie not concentric) with the originals and the bolt circle and pressfit work out fine.
Fab work to install. Now I think I can figure out how to make bracketry to mount the beam and the differential into the car.... Factory the Scorpio stuff is rubber mounted, but I would solid mount it just like I recently did in the Scorpio.

The only other thing I will need to do is tweak the trailing arm mounts to correct the rear alignment at ride height. I need to do that anyway for the Scorpio (sits lower than stock), so I'm going to plug numbers in my Mitchell Geometry program and move things around to correct that.

OK, now "why" you say? Well the obvious would be because I can. This would not be slated for the silver car, but for one of the other two. It might wind up under the 80 XR-7 just to try things out, who knows. I'm curious about how the ride would improve as well as handling. While it's not an SLA setup, it still feels leaps and bounds over the live axle in the car.

Anyway...just more ramblings of a crazy man...:wtf: :screwy:

Perhaps I do have brain damage (rear suspension idea)

Reply #1 – January 08, 2007, 09:30:12 PM

sounds kick ass!

lemme know if you need an extra hand for test fittin stuff

Perhaps I do have brain damage (rear suspension idea)

Reply #2 – January 08, 2007, 09:49:38 PM

I dug up a pick of a Merkur rear suspension for those who are unfamiliar. the Scorpio is the same except it has rear disks and is 5-lug

Perhaps I do have brain damage (rear suspension idea)

Reply #3 – January 08, 2007, 09:52:11 PM

Try it:grinno:

Perhaps I do have brain damage (rear suspension idea)

Reply #4 – January 08, 2007, 09:55:34 PM

So Chuck... this means camber will change with suspension compression. Your ok with this?

Perhaps I do have brain damage (rear suspension idea)

Reply #5 – January 08, 2007, 10:24:47 PM

I'm aware what the STA suspension does. With the camber corrected at ride height, the change during compression won't be all that bad really.
I've been driving the Scorpio around with uncorrected geometry for a few weeks now, and it's really not a problem.

We're also not talking about HUGE changes as the travel is not going to be massive.

Even the Cobra stuff changes....

It will be liveable. I'll know how much it's changing when I plug the numbers.

As an interesting side note.... with the current rear suspension, I picked up the new shortblock for the '83. It was on a skid, so probably 200# of weight. The back of the car only dropped 1/4" when I put it in the trunk :p

Perhaps I do have brain damage (rear suspension idea)

Reply #6 – January 08, 2007, 10:50:22 PM

Finish the SHO transplant...then focus on the Merkur-madness. :D

Perhaps I do have brain damage (rear suspension idea)

Reply #7 – January 08, 2007, 10:55:24 PM

Well the first order of business is getting the '83 back on the road...

Then we'll see what takes up the next spot...

Perhaps I do have brain damage (rear suspension idea)

Reply #8 – January 08, 2007, 11:02:38 PM

Sounds interesting but how much power can one of those rears handle?

Perhaps I do have brain damage (rear suspension idea)

Reply #9 – January 08, 2007, 11:07:00 PM

It sounds like a great idea, but I wonder how much fab work will really be needed. Keep us posted. :)

Perhaps I do have brain damage (rear suspension idea)

Reply #10 – January 08, 2007, 11:27:47 PM

Quote from: 86elan;122660

Sounds interesting but how much power can one of those rears handle?

Well I would not be keeping the stock Merkur diff. As far as the strength of the rest of it...it depends. It shouldn't have an issue with 300hp. The halfshafts would be the only other concern.

Perhaps I do have brain damage (rear suspension idea)

Reply #11 – January 09, 2007, 12:33:09 AM

Would that even bolt to the lower controll arm mounting points? If so you might have something there.......

Perhaps I do have brain damage (rear suspension idea)

Reply #12 – January 09, 2007, 02:10:38 AM

You are seriously going to have the most badass lot of oddball cars when you're all through with these projects. I say go for it.

Perhaps I do have brain damage (rear suspension idea)

Reply #13 – January 09, 2007, 03:09:21 AM

Bolts? Bolts?! Chuck don't need no stinking bolts!

Perhaps I do have brain damage (rear suspension idea)

Reply #14 – January 09, 2007, 07:14:59 AM

Quote from: thunderjet302;122688

Would that even bolt to the lower controll arm mounting points? If so you might have something there.......

Well it's hard to say just yet. The location looks to be close. It may require cutting the mount of the beam and fabbing/welding a new mount to attach into the factory RLCA mount points.