Thursday, April 19, 2012

4-Link Bracket Work & Mock-Up – If it was easy, everybody would be doing it

In the middle of lots of non-Boss related work bleeding my time away, I have managed to make some progress on the rear 4-link coilover suspension…….and learned some valuable lessons along the way.
For several weeks, I have been trying to resolve a problem I discovered with the 4-link brackets that are included with the Heidt’s 4-link coilover suspension kit.  Quite simply, the brackets that are supplied were made for a 3” axle tube diameter which no classic Mustang ever came with (3” axle tubes are a popular aftermarket housing thing).  In 2011, I had an email contact at Heidt’s that I was communicating with on other things and decided to see what could be done to exchange the 3” OD brackets for the properly sized 2.75” brackets I needed.  After a number of tries, I was getting nowhere fast and ended up calling the dealer I bought the kit from (Tim’s Hot Rods) at Heidt’s recommendation (their policy).  Tim Stromberger (fantastic guy!) had never heard of the problem I was having so I explained Mustang axle tube sizes to him and he made notes for future reference.  He called Heidt’s on my behalf and I got set up with a new contact, much higher up the food chain than the individual I was originally working with (who evidently was no longer with the company).  After a few conversations back and forth and some philosophical point and counterpoint, I learned that Heidt’s had “small” tube brackets they offered in the instance that the supplied brackets didn’t fit, so I jumped on that like Rosie O’Donnell on a doughnut.
A few days later, the “smaller” brackets arrived and I realized my first error:  In my excitement to solve the problem, I didn’t specify what axle tube size I had and the brackets that were sent were for the rare and ultra-small 2.5” axle tubes.  S*(&^%#T!  Another few phone calls and we determined that the proper 2.75” brackets did not (yet) exist to allow a stock 9-inch Mustang axle housing to be used with the kit.  Apparently, most of the kits Heidt’s sells include their axle housing option with the brackets pre-installed and this never came up before.  So, the guys at Heidt’s went back to the drawing board and produced a new set of brackets for my 2.75” axle tubes and sent them my way in about a week and we were in business (thanks Mike)!
So, the lessons learned are rather simple.  Never again will I get so complacent with the ease and convenience of email communication.  When technical issues arise like this, I will be much quicker to pick up the telephone and persist until I talk to someone who can help (what’s old is new?).  This same policy should apply when ordering parts to make sure what is offered will in fact fit “out-of-the-box” or if certain models may require alternate parts. 
Secondly, never assume a parts manufacturer knows more about your car than you do.  As much as we may like to believe that every supplier is an expert on the intricacies of our beloved ponies, this will rarely be the case as they are often in the business of offering parts for many different makes of vehicle, making absolute expertise nearly impossible for them to approach. 
And third, you never know what benefit may come from running a problem all the way to ground such that a genuine solution is found.  As frustrating as the process may have been, the end result from this rather protracted exercise is the satisfaction in knowing that Heidts can now supply Mustang 4-link axle brackets to fit 2.5”, 2.75” and 3.0” axle tubes, and that is good for the market in general.  Now, let’s get on with it…..
 After getting some of the minor repairs completed on the axle housing and in between stints working on the 9-inch center section, I was finally to the point that I could get the housing brackets tacked into place and the system mocked up in the car to verify fit (and entertain myself good bit as well).  A digital angle finder was indispensable in easily getting the bracket angles perfectly set to allow me to tack them in place.  This is definitely a 2-person job and my bestest buddy and partner in crime (a.k.a. Dad) put up with my endless fiddling and fussing to help me get things just right.  Once we had the 4-link brackets positioned and tacked into place, it was time to see what the setup would roughly look like under the car, bearing in mind that the panhard bracket could not be mocked-up as that can only be put in place after the 4-link brackets have been permanently welded.
With the car on its side in the rotisserie, we were able to easily place the empty axle housing in place while we loosely hung the short and long links as well as the top coilover mounts.  With the axle basically located, we loosely connected the lower coilover mounts and rolled the car level to have a look at things.  And like so many other things we have completed on this car, the look of the coilover rear makes me smile……big.  In simple street terms……it looks pretty bad-ass and will be even better when it is completed.
I have a lot of work left in the rear suspension and several modifications I plan to make (much to Heidts’ chagrin I am sure) to improve the suspension’s roll-bind characteristics and allow much easier suspension setup, alignment and tuning.  Those modifications will of course be documented here, but at least for now, I can move forward with the remaining housing modifications, sandblasting the housing, continuing the build of the 9-inch differential, rear caliper rebuilds and installation, brake hose and hard line routing and powder coating the whole works.  So in short, I am plenty busy, even though it doesn’t really LOOK like it at the moment.  More to come!
With the help of my Dad and a nice digital angle finder, tacking the 4-link brackets to the housing was not difficult.  This is the view from the front of the housing where the 4-link bars connect.

From the back, the brackets are quite tidy looking.  The three holes at the lower part of the photo are where the bottom of the coilover shocks mount.

With the car on it's side in the rotisserie, it was a easy job to loosely hang all of the parts on the housing and the chassis for mock-up purposes.

Here is the lower arm chassis mount without the steel spacer installed.  Since I will be reconfiguring this entire end of the arm, the finished installation of this connection will look completely different than this photo.

I can't help but like the look of this suspension under the car.  It is quite a motivator to see things start to take shape.

Another shot showing the simple functionality of a compact 4-link coilover rear suspension.


  1. Leaf springs ain't good enough for ya huh!? :-)

    Seriously though, that's going to be one bad-ass ride my friend. Nice work. Also, it's amazing that you got some custom brackets made. Now THAT's customer support.

  2. Okay! I admit it! I am spoiled with coilovers! LOL!
    As for the brackets, I'd prefer to look at them as "correct for the application" which should serve Heidts well in the future. But yes, they were quite helpful and they look great!

  3. I'm surprised you didn't fabricate the brackets yourself after the first dead end. That is one amazing setup and yes, nothing is the way our minds think they should be. Especially sheet metal panels, doors, fenders, and even 4-links. Awesome work. I am always amazed at your attention to detail.

  4. Hello James and thanks for stopping by! Honestly, for the money I spent on this kit and the headache it would have been to reverse engineer the 4-link geometry, the thought of fabricating the brackets myself was downright irritating. At the end of the day, all of the wrangling _should_ help someone avoid this problem in the future and the Heidts guys have one more bullet in the chamber for the classic Mustang crowd. Stay tuned on this phase of the project because I have a lot of nifty upgrades that are coming on this suspension setup that should prove entertaining at the very least. Take care!

  5. Sven, I went through the same thing back in the 80's with TCI on my 29 Model A 4 link on the axle diameter. Seemed they had the one for 9" housings but not the 8" until I told them that's what I had. I got new brackets and in their next catalog, there were both listed. So welcome to the world of prototyping for a company. BTW, that is one slick set up. That Boss will corner like it's on a rail! Great usual!

  6. Thanks Dennis! I guess it gets under me a bit more than it should based on the fact that I fuind myself doing this same sort of thing all too aften in my "day job" (also automotive related) and it can take so much of the fun out of things. Otherwise, it's all good!

  7. Sven, if you get backed into a corner like that again - feel free to give a shout. What a better use for a waterjet than fab'ing Boss parts :) I'm sure you are already itching to gradually squeeze into the throttle coming out of one of those beautifully engineered interstate cloverleaves. That thing will stick to the pavement and just keep pull'in! Sweet!


  8. RJ,

    I can't tell you how much I appreciate that! I have been quietly DYING to see that water jet of yours go to town!

    I have to admit that the experiences I have had in the Mustang hobby have given me more than one opportunity to consider the design and manufacture of parts/systems that are a cut above what's out there.

    Ans one of these days, this old car will be complete and you're going to have to plan an extra day when you're in the area and we'll have to take a few laps of Woodward Ave!