Pro-touring rear suspension?

[ProCobraII]

Hey guys I would appreciate any input on my rear suspension you can offer. I'm building a 76 cobra II and want to put a narrowed 9in in the car that I already have. I want to run 10" or 11" rear tires so I need to mini tub the car which requires getting rid of the leaf spring rear suspension or moving it inboard. I plan to drive this car on the street mostly and maybe some track time. I would like it to handle better than a new mustang and handle at least 600hp with a manual trans. So my question is do I go 4-link, triangulated 4-link, 4-bar or what? I have to do the work myself but I'm sure you guys understand that no only for financial reasons but because I want too. I really was leaning toward triangulated 4-link until I read some of the threads in here and now I'm just unsure. I would also like to add that this is the first rear suspension I have ever attempted to build so I need all the help I can get. I would like to run coil-overs for the adjust-ability but I'm open to any suggestions. I hope I covered all of the pertinent information and thanks in advance guys

[Norm Peterson]

It may come down to how hard you really end up driving it, and just what kinds of "hard driving" we're talking about. FWIW, I think that in the smaller chassis the rear roll center height becomes more important than in bigger cars.

In a triangulated 4-link, you can tune the anti-squat and roll steer but are pretty much stuck with a high rear roll center (read excessively high if you intend to seriously compete at autocross or drive it really hard at track days). As a variation on the triangulated 4-link, a Satchell may be a better choice, although you may not have a whole lot of roll center height option there either. Just about anything else binds up in either two wheel bump or in roll - or is wildly more complex in terms of tuning.

Let me suggest a 3-link. Since you're in for some tuning, that arrangement can separate traction tuning (anti-squat) from the handling aspects (roll center height and roll steer) and probably gives a wider range of tuning than a torque arm arrangement would (the torque arm being a fairly close second choice IMO). One would think that Ford (for the S197 Mustangs) and the modern-era Trans-Am teams (1980 - 2004) chose this basic arrangement over the previously used arrangements for a reason.

Regardless of which sort of link arrangement you decide on, there will be a need for adequate additional structure to pick up the upper link or links (or the chassis end of a torque arm should you end up running that option).

Norm

[ProCobraII]

Hey thanks Norm I never thought of the 3 link. If I were to look up some of the newer trans am cars that is what I would find? Also when you say structural support for the front links this is something I have thought about. What do you do for a subframe car like mine when all you have is the floor pan? Do I need to run a tubular or square cross bar somewhere between the back of the trans and the third member from one side of the frame rail to the other or what? Oh and thanks again for the advice.

[ProdigyCustoms]

We sell a lot of the Chris Alston G Bar. There bolt in with only minor welding of some tabs on the rear, and work awesome! For the money ad ease of instalation, and performance, you can not beat it

[MonzaRacer]

Or if you want even more awesome step up to Air RideTechnologies for air spings instead of coilovers, yesmore money but if you want to make it handle it would and still ride great and you cna get it low enough to look good.
dont get me wrong its not going to be the easiest on that chassis and the MSII front isnt the easiest to get to handle(bad geometry) but it can be made better.
Good Luck
Lee Abel

[chicane67]

Or if you want totally bad ass... step up to a http://www.lateral-dynamics.com/ 3-link. I am sure Mark could whittle something up for you.

Jeebus... listen to all the pitches... that is damn funny.

But Norm's got it right. 3 Link all the way.

[jason@gmachine]

we have redesigned our kit and will have it available within 30 days.

new features.

-improved geometry
-all 4130 construction
-Penske shocks with Res.
-GMR chromoly heims
-serious bulletproof construction.



T minus 30 days!

Jason

[SN65]

The Mustang II is a bit different than other Mustangs. You have both front and rear suspension isolation systems. Also, anything that you do will require modification on your part. Frame rail relocation. Reconfiguring the overall chassis, etc...

Before you start, come up with a cohesive overall plan. Start with all the chassis modifications. What else are you going to have to modify? Where are you going to run the exhaust? Instead of tubbing the car, maybe fender flares are a better way to go. IF handling on a autocross or road course is your primary concern, shifting the tires outboard will help much more than shifting them inboard.

You are talking about 600HP. Is that to the rear wheels? About 600 lbs of torque also? If that is the case, how are you going to attach your 3rd link to the rear end. Depending on the amount of leverage and the attachment point you could be applying in excess of 15,000 PSI. Will the attacments, as well at the rear end casing, hold up to that amount of pressure without tearing free or crushing the case?

There is a lot to consider. Again, start with the chassis and work your way from there.

Good luck. I love the MII and think that you will have a killer car when finished. Hope this is of help.

[jason@gmachine]

You are talking about 600HP. Is that to the rear wheels? About 600 lbs of torque also? If that is the case, how are you going to attach your 3rd link to the rear end. Depending on the amount of leverage and the attachment point you could be applying in excess of 15,000 PSI. Will the attacments, as well at the rear end casing, hold up to that amount of pressure without tearing free or crushing the case?



i have a solution.

1.25" by .120 wall 4130 link arms with 4130 bungs.
GMR chromoly Teflon heims rated at 41,000 Static Radial Load
upper link mount, laser cut 3/16" 4130 for precision
housing, TIG welded 4130 link mount welded to a steel (not cast) housing.

Jason

[jason@gmachine]

T minus 29 days!


Jason

[ProCobraII]

Hey guys wow I really appreciate all of the suggestions and advice man I love this forum! Hey Jason I'm very interested in your 3 link please keep me informed and any info would be great. Thanks again guys and keep the suggestions coming please.

[jason@gmachine]

Hey guys wow I really appreciate all of the suggestions and advice man I love this forum! Hey Jason I'm very interested in your 3 link please keep me informed and any info would be great. Thanks again guys and keep the suggestions coming please.

I will start a thread when the time is closer.

also, we can step it up another notch and offer 7/8" GMR chromoly heims (55,692lbs Static Radial Load) with 1.5" by .120 chromoly link arms for those looking for serious HP/TQ strength!

Jason

[Kenova]

Here you go. Although the search/link may not answer your question directly, there is a lot to be learned from this member.

https://www.pro-touring.com/forum/search.php?searchid=537357

Ken

[SN65]

You could always build your own. Here is what we are working on right now.

http://sn65.com/images/Fire%20&%20Ice%20Images/Fire%20&41.jpg

The rod ends we are useing sound similar to those mentioned by Jason. Except that ours feature a self-lubricating, self-sealing PTFE/Kevlar race (instead of teflon). Also, under heavy shock loads (suddenly applied loads), the ball makes contact with the metal for added support (without distorting the race).

What ever you buy, make sure that it is suitable for your torque output. We needed something able to handle over 1,000 HP and 1,000 FPT. We did not see anything available we were comfortable with at that level so, we are building our own.

Good luck on your project.