If you don't mind and have the time I'm actually interested in learning these reasons. Judging by your sig though, I probably shouldn't ask

 

I'm building the lowest and smoothest riding 4th gen in the world.

4 wheel independant suspension with air ride.
It's going to handle as well.

 

Gotcha. It all makes sense now.

 

be sure to thoroughly document all your steps, then you can turn around and sell the plans to some company, and they can start making kits, and you get rich in the process

ok, wishful thinking, i know.....but good notes would be helpful anyway

 

No one wants this.

Maybe 3rd gen owners who want to swap from a strut to a SLA design for better handling.

 

I think there may be too many variables in using a different spindle. What I prepose is to modify the stock units by shortening them and welding in a round section at the top to mount a large uniball joint. The uniball will give plenty of articulation and are used on many offroad racing trucks.

This is an example of what I mean:



So we take the stock spindle:


Then find it's rotating axis point which runs through the upper and lower balljoint centers:


and add the new joint on that same axis along with a little reinforcement:


and voila! Now you just have to make the upper arm and get the mounting location right.

 

w2w was doing something sim to what you want,check in the shop tour threads. im building a cp auto x car and was thinking the same thing. mount upper control arm to the frame rail, run a bar from the dash bar to frame and then a triangulated bar simalier to a3pt stut bar also tied to the dash bar. the key would be the right spindle colman might have something. the benifits would be

get rid of the crappy stock wheel bearing
run a 25x12x16 goodyear
fix the bump steer
any brake caliper

 

I talked to one of the local street rod gurus briefly, and he said it shouldn't be too bad. If I ever get time, I'm supposed to go over too his shop and throw around ideas, and see if he will be able to help me with it. My third gen will be the guinea pig, but the 4th gen setup will be discussed also. It will probably end up being a setup very much like this one you posted:



Jason, on a side note regarding IRS, another one of the local street rod guys builds IRS for lots of old stuff. He has a Tbird and Jaguar IRS that I can take measurements on. Plus, he can narrow the cradle and axles if needed also. So if you wouldn't mind taking some measurements on the fbody (like track width, etc.) I could take measurements on those rears. Maybe one of us could get something started on that.

 

I already started on that. I have a 97 Tbird daily driver (MN-12 platform) and already took lots of measurements on it as well as overlaid photos of that rear end under my 98 TA. Track widths between the 2 cars are almost identical at 65". I plan to use a Cobra center section as they can be bought in 3.73 Trac-loc for around $300, but use a 31 spline inner hub and 28 outer. T-bird axles have 28 splines on both ends. I can get some Cobra axles which are a little bit shorter than the t-bird axles and just shorten both A-arms. Then I will have a track width of 62.25". The narrower track will allow me to use some adapter hubs to fit my f-body rims on. So it all works out fine. I basically just need to find a good donor car. I'm looking for a flooded or wrecked Mark 8 cheap. Those cars already have an air bag setup on all 4 corners.

 

I got to thinking about the 3rd gen design and am considering building the upper a-arm mount into the stock k-member. Maybe even the new upper shock mount to it as well. It would be a heavy *** k-member, but I could cut away the sheetmetal towers completely. Seems like a fair trade to me.

This way the complete front suspension would drop down with the engine and k-member.

 

^^^^ that should work, but just make sure you have all the correct geometry. You will basically be building your own front suspension system, less the lower control arms. If I was to do this, I would look at the street rod IFS kits that have a crossmember and everything. They have brake and spring options too. I dont know if these would work on our cars, but it might give you some ideas.

something like this

 

The Mustang 2 setup is not that good, but I see your point. The above setup won't work on our cars.

That's the basic concept, though.

There's a company here in Houston called Ektensive Customs that do body drops and build suspensions from scratch. I'm going to leave the final upper arm mounting to them.

 

I know you wouldn't want to use the mustang II suspension, but i was just trying to give you an idea of what could be used. They have many many different suspensions like these for hotrods that arn't based off of the mustang II. I think if i was going to attempt this I would build a whole front clip and just start with a clean slate and use a complete custom front suspension. That would get rid of that horizontal bushing in the lower control arm too.

 

What I'm saying is these universal units won't fit our cars. The steering rack, oil pan and k-member shape are are designed to work together. It's much, much easier to use the existing components.

 

I could really use some ideas on fitting the uniball collar to the spindle. I plan to cut the shock towers out real soon.



This looks like the plan:


The only tricky part is I'd like to not weld the collar to the spindle. I think they can be bolted together if done properly. The collar that the uniball fit's in is shown below. This piece can be welded on easily.



Keep in mind there's almost no up down force on the upper ball joint. It's moslty left and right such as in cornering with a lesser degree in front to rear movement when under braking or running over a bump/pothole. So I need to focus on the left and right loads primarily.

 

You wont be able to turn the wheels with that type of joint on the top. It will go up and down perfectly fine, but will not allow the spindle to rotate.

 

The joint is fine. These 1" uniballs are used in lots of race vehicles. Mainly off road Trophy Trucks. They turn fine left and right when used with the high articulation spacers.

If it turns out I need more articulation left and right than I need up and down, I can always turn it 90* and mount it so the bolt goes up and down instead of level with the ground as on my picture.

 

Ok, I see from the pictures that it will articulate a little, but it just doesn't seem like it would be enough. Parking spots and such will probably be a PITA.

 

A little? It can move more than a ball joint can. Check out this pic:

 

Bringing this back up a bit. I found this over on TGO...I think I might go this route. Except use upper control arms and box the frame where the tubing welds on. This is on a third gen, but the same could be applied to the 4th gen.