MII Strut Failure HELP!!!!!!!!!

[GPster]

Are you working on your doctorate degree in the physics of Mustang II suspension (or do you already have it)? You and Bob Paulin could teach a class. Now what we need is someone that is computor savy to take this forum and our archives and put every thing about Mustang IIs and Pintos and put it on a disc. Then maybe RRT could sell it to Tex Smith and put the money in the fund. Rooster, how hard would it be to cut that crossmember loose and tilt it back? GPster

[Bob Paulin]

Are you working on your doctorate degree in the physics of Mustang II suspension (or do you already have it)? You and Bob Paulin could teach a class.

Although we are geographically separated, I suspect that Peter and my backgrounds run on a bit of a parallel.

A lot of the stuff he presents is sound race car design and engineering, and it is very familiar to me.

And, yes, I DID teach Vocational Auto Mechanics for 10 years which included a smattering of adult ed programs including an annual Basic Stock Car Chassis Preparation course which oversubscribed every year.

Now what we need is someone that is computor savy to take this forum and our archives and put every thing about Mustang IIs and Pintos and put it on a disc. Then maybe RRT could sell it to Tex Smith and put the money in the fund.

You would be shocked at how little money there is to be made with technical books these days.

I've just ordered a technical book on racing tires by a respected engineer that has been out for two years, and I am the 373rd customer for this book.

Having said that, I DO believe that there is a place for a technically-oriented chassis prep book - one that discusses modifications, alignments, etc. - not just bolt-on stuff.

I look at the "How To *****" books these days, and they mostly tell you which components to buy and bolt-on.

I realize that there are liability issues, but disclaimers and insurance can overcome much of that problem.

I, myself, have had several false-starts down the road to a chassis book.


Oh well!

B.P.

[Bruce Dorsi]

You (PeterR) and Bob Paulin could teach a class.

AMEN!  .....Having the knowledge is one thing.  

Being able to convey and explain that knowledge in a clear, concise,  and easily understood manner is indeed a talent!   ...(Peter's graphics always simplify the learning.)

Thanks, Bob & Peter!  ....Please don't think that you are wasting your time with your explanations here, as I always learn something from you guys!

Now, how about an answer to Tomslik's question, about relocating the struts, so they face forward, please?  

~~~~Bruce
ps: Bob, how's your cousin doing on the track this summer?  ....I was in Shediac in July, and passed thru your area on our way north.

[rooster]

Thanks guys for the great information, ideas, demos! And I do understand more from it! I'm sure others have to.

I have never installed or taken part in any installation of  a MII front-end. And I'm hesitant to apply the longated of any bolt holes to make a guessed correction. As far as taking a torch to the crossmember and readjusting by cutting and re-welding, I don't think that's the thing for me to do at this time, because of the lack of experience I have!

I do plan on constructing a 3/8 plate to the bottom of the frame in the approximate location of where the other failed, that plate will support a beefed up 1/4" bracket to hold the original Ford strut rod! If that doesn't work then the torch!

In a special comment about what GPster was saying about getting the information about MII  from archives and selling it. I don't think so. I think those who have contributed any useful information in the past and in the future are offering it to the forum and those who have interest in the hobby, members or lurkers. As a group we have failed to see that their
contributions remain here intact and useful. An attempt was made asking for volunteers to go through the archives and pick-and-choose different posts of  value. I don't know what ever became of that. I can seen why people who make such posts are reluctant to do so again! I for one respect the time & effort of others to share their knowledge of the hobby.

Again Thanks!!!!!!!!!!!!!!

[GPster]

In a special comment about what GPster was saying about getting the information about MII  from archives and selling it.

This is one of the problem with my talking too much. The more I say the bigger chance I have of someone misunderstanding me. The comment was made mostly with the idea that certain of our members have been  contributors in the Tex Smith publishing empire. My problem is the more I see the less I remember what I'm looking for. Archive is a BIG word, Book is neater. GPster

[PeterR]

I do plan on constructing a 3/8 plate to the bottom of the frame in the approximate location of where the other failed, that plate will support a beefed up 1/4" bracket to hold the original Ford strut rod! If that doesn't work then the torch!

Before embarking on any work you should carry out the test to establish correct position for the rear bracket. If the standard bracket is installed out of alignment, every time the suspension responds to road irregularities there will be flexing of the strut near the bend at the outer end and additional cyclic loading on the bracket.  

The strut may have been bent at some time and this might be giving a worse impression than really exists. All it will cost is a couple of dollars for 2' of bar, and half an hour of your time.

Purchase about 2' of "bright" steel bar (not black bar which has inconsistent diameter and is never straight).

Fit the large steel washer on the strut then mark the shank midway between the washer and the shoulder where the diameter reduces. This is to identify the position of the "pivot" point on the strut.

Remove the lower arm pivot bolt from the cross member and replace it with the test bar. Slide the bar backwards until the end of it reaches the strut rod. (The arm can not carry any body weight at this time.)

If the strut has been bent it may have to be tweaked up or down to bring it to the same height as the test bar, and perhaps bent backwards or forwards so the end of test bar touches the strut shank at the mark made earlier.
Although it may be a pain, it is worth jacking the arm up to ride height (still with the test bar in place) then if necessary bend the strut again slightly to bring everything into line.  

Now you are able to fully assess the situation and make an informed decision on which way to jump.

Although you have expressed apprehension regarding elongating the hole, this would be a good time to do the measurements described earlier and calculate the amount to be filed out.

One comment on welding a standard Ford type bracket to the frame.  The strength of this connection will be enhanced enormously with three triangular gussets welded onto the bracket so in combination with the existing bent reinforcing web it would look like an H from below. The base of the triangles should be long enough to run across the full width of the frame rail.

[rooster]

I do plan on constructing a 3/8 plate to the bottom of the frame in the approximate location of where the other failed, that plate will support a beefed up 1/4" bracket to hold the original Ford strut rod! If that doesn't work then the torch!

Before embarking on any work you should carry out the test to establish correct position for the rear bracket. If the standard bracket is installed out of alignment, every time the suspension responds to road irregularities there will be flexing of the strut near the bend at the outer end and additional cyclic loading on the bracket.  

The strut may have been bent at some time and this might be giving a worse impression than really exists. All it will cost is a couple of dollars for 2' of bar, and half an hour of your time.

Purchase about 2' of "bright" steel bar (not black bar which has inconsistent diameter and is never straight).

Fit the large steel washer on the strut then mark the shank midway between the washer and the shoulder where the diameter reduces. This is to identify the position of the "pivot" point on the strut. (rooster) This equals about 1 1/4" to where the bracket rests on the strut!

Remove the lower arm pivot bolt from the cross member and replace it with the test bar. Slide the bar backwards until the end of it reaches the strut rod. (The arm can not carry any body weight at this time.)

If the strut has been bent it may have to be tweaked up or down to bring it to the same height as the test bar, and perhaps bent backwards or forwards so the end of test bar touches the strut shank at the mark made earlier. (rooster) It looks like the strut needs to come up about 5/8"!
Although it may be a pain, it is worth jacking the arm up to ride height (still with the test bar in place) then if necessary bend the strut again slightly to bring everything into line.  (rooster) Pictures were taken with test bar in , all jack stands removed, and jacks, car on ground!

Now you are able to fully assess the situation and make an informed decision on which way to jump.

Although you have expressed apprehension regarding elongating the hole, this would be a good time to do the measurements described earlier and calculate the amount to be filed out. (rooster) I think you are saying file only the crossmember, to do this, remove the bottem arm? Ill have to go look at the math thing again.

One comment on welding a standard Ford type bracket to the frame.  The strength of this connection will be enhanced enormously with three triangular gussets welded onto the bracket so in combination with the existing bent reinforcing web it would look like an H from below. The base of the triangles should be long enough to run across the full width of the frame rail.

[Bob Paulin]

ps: Bob, how's your cousin doing on the track this summer?  ....I was in Shediac in July, and passed thru your area on our way north.

Up until last week, Dan was the only driver with two wins in the Sportsman Division - it's THAT competitive up there.

Last week, though, I just read that last year's champion won his second of the year.

I've been on the road for a week doing some "Train the Trainer Training" or "T-3" and just got back a few minutes ago.

Spent those motel nights starting an outline for a technical chassis book - YEAH! I know there are a million out there, but I want to try something a bit different.

Decided to do a quick check of my e-mail, and touch base.

I'll get more involved in a day or two.

B.P.

[enjenjo]

Now, how about an answer to Tomslik's question, about relocating the struts, so they face forward, please?

Since no one else is answering, I'll step up. I have installed them facing forward in the past, seemed to work OK. I based my decision to do it that way, on the fact that ford on some of the Fairlanes installed the struts forward, also full size GM cars 65 to 69 had forward struts, and some AMC cars used them forward too. I was concerned with interference with the steering rack, and sway bar, but every thing cleared with no problems.

Also, on using struts with a curve bent into them, I just finished a 500 mile trip with a car using struts with a bend in them, part of over 6,000 miles on that car. so far, no ill effects. Of course the bend is very near the strut bushing, and the mount is properly gusseted. And the possibility of bending the strut if you were to hit something solid with the wheel is always present. but that is not necessarily a bad thing, replacing a strut is easier than straightening a frame.

[Bruce Dorsi]

Thanks, Frank!

[rooster]

The more you look at it the more you realise the factory design was not so silly after all.

Now to your particular problem. You have reached the conclusion the cross member was installed tilted forwards; and as a consequence the hinge axis of the lower arm slopes upwards towards the rear of the car, making the correct position for the original rubber biscuit pivot too high to fit under the frame rail but a rod end might squeeze in.


There is a lot of work to fit the rod end, and I suspect there might be a quick and dirty way to overcome your problem.   From the photos it would appear as though the original biscuit mount only just misses out fitting under the frame rail.  If that is the case you could elongate the rear hole in the cross member downwards so the hinge line does not run up at such a steep angle.

Yes it is crude, but the amount to be filed out is likely to be quite small.  Don't be concerned about the elongated hole, the spring force will hold the bolt down hard against the bottom of the hole, and any worriers should look at an Aussie Ford cross member which has an elongated hole that allows 1/2" horizontal movement of the lower pivot bolt for camber adjustment.

The relative heights of the lower arm pivot and the tie rod inner pivot will change marginally, but the effect on steering will be minimal.

You can easily calculate how much the hole has to be elongated to decide if you are comfortable with embarking on this act of brutality.
   

I wasnt able to figure the math ,so next best thing is file it 1/16th at a time and recheck with test rod until angle is not as steep and below frame rail!

Question: To elonggate the the rear hole in crossmember (bottem edge) is it nessary to remove completly the bottom arm that the bushing is in?
If so How do I do this?  
Anyone!
I have never done this before.

[enjenjo]

First off, remove the spring. To remove the spring, support the lower control arm as near the spindle as possible with a jack, remove the shock, remove one of the ball joint nuts, usually the bottom, and remove the ball joint from the spindle. Once the spindle is loose from the control arm, lower the jack to take the tension off the spring, and remove the spring.

Once that is out, remove the bolt, and the lower control arm will come right out.

[PeterR]

I typed this up about a week ago but did not get to post it before going away so there is some overlap of earlier messages by others.


Judging from the photo: -
As we had expected the hinge line rises towards the rear of the vehicle.  There appears to be about 1/2" clearance between the bar and the underside of the rail.

The strut is sitting below the test bar.  It might have been bent downwards previously to align with the mount that had broken away.  It can easily be bent up to the correct position.

The front-rear position of the strut appears to be OK with the "hinge" point of the strut shank in line with the test bar.

What are options: -
1.  Cut out the cross member and refit to correct angle.
Great end-result but a heap of work, particularly as rework is always more difficult than the original installation.

2.  Use a rod end so the hinge point can be raised to the correct height.  Geometrically it is fine but rod ends have very short service life in these applications. There is a rod end that uses a rubber bush instead of a sliding ball for articulation. This looks ideal as there is no sliding movement so no wear, but I suspected they are only capable of a few degrees of movement so called the manufacturer and they confirmed this, ruling them out for this application.

3. Run the struts forward.
First let's assume there are no interference problems with the steering gear.   The pivot can be placed in the geometrically correct position, the strut itself is at least as strong as for rear mounting and the factory style bracket can be deployed.   This is a very effective solution but there are a couple of points to note.

Regardless of which way the strut runs the pivot must lie on the hinge line as depicted by the test bar.  The hinge line runs downwards to the front of the vehicle and this means the bracket will be quite low, even lower than the cross member pivot bolt.  As indicated in an earlier post the forces in the strut are quite substantial and a bracket hanging that distance below the frame will require careful bracing.

Whether this will have ground clearance implications can be checked quite quickly.   Measure the distance from the cross member to the correct position for the rear bracket.   Make a mark on the underside of the frame forward of the cross member the same distance. Slide the test bar forward and check the height of the bracket below the mark on the frame.  

4. Use the aftermarket strut
From the photo, there appears to be just sufficient clearance under the frame for the tubular strut bush to lie on the correct hinge line.  This ensures the correct geometry but as indicated earlier I have reservations about this product as the curved shape significantly reduces the compression strength of the strut, and the bracket makes little allowance for the rearward directed braking forces. I have pondered as to the reason for the curve in the strut and can only speculate this was done to provide clearance between the strut rod and the inside faces of the bracket plates for every conceivable mounting position.

As first year university students we carried out an experiment loading up a strut until it failed then repeating this with a strut of same dimensions but a gentle curve in it.  The curved strut failed at about one quarter of the load.  That was 40 years ago and since then I have avoided curved struts and eccentric loading like the plague. Enjenjo, -a person we all hold in high regard indicated he has used this product without problem; perhaps I am allowing my deep-seated distrust of curved compression members to overwhelm practicality.

There is still the issue of the bushing having little provision for the rearward force though that could easily be fixed by a urethane thrust washer or using urethane shackle bushes which usually have a healthy flange.

5.  File the hole
This is the easiest solution by a mile --provided you only have to cheat a small increase in clearance at the bracket. I would not feel convertible elongating the hole more than 1/16" and this will probably gain about 3/8" at the bracket.  It is very difficult to tell how much extra is required from the photo.

Before rattling the file it would be wise to run a few checks. Loosen off the two bolts securing the strut to the lower arm.   This will allow the end of the strut to drop down a bit.  Fit the two washers and rubber bushes onto the end of the strut. Raise the arm so the rubber bushes are as close to the underside of the rail as could be mounted and still provide full range of suspension movement. Measure how far the strut shank is below the test bar --this is the distance you have to "cheat".  If it is more than 3/8" I doubt filing the hole is the solution.

6. Forget about the correct geometry and just mount the bracket as high as practicable.
Simple to do but in normal service there will be additional loads in the bracket and the strut. I believe the most sinister of these is the repeated up and down flexing of the strut where it is flattened down for the bolts and this could easily result in fatigue and ultimate fracture at the bolt hole.

7. Mount bracket where convenient and make provision for misalignment.
Mount the standard bracket as high as practicable and provide a flexible connection where the strut joins the lower arm. This is easier than it sounds.

Cut off the strut a couple of inches from the boltholes (exact place will become apparent later).  Weld the eye from an old coil-over shocker to the end of the strut.  Weld two plates to the rear of the arm to provide a double shear bracket for the shocker eye. The bolt should be horizontal so the strut can move up and down relative to the arm without inducing any nasty forces in either component.  

Each eye of a front coilover carries a load in excess of half the body weight so it has heaps of strength, there just needs to be a little care in fabricating the bracket.

[rooster]

I'm trying to pick up where I crashed 2 years ago. I do not understand # 7.
What is the purpose of cutting off a strut 2" from the bolt holes. Is this going to be my
new strut? I hate being a pest . And thanks again for your help! :oops:

[Charlie Chops 1940]

Geez, I missed this whole thing 2 years ago when my wife and I were gone for 3 weeks going to Bonneville and back.

I put a Heidts MII kit under my '40 Chevy convert about 17 years ago. I dumped it pretty deep in the weeds by removing 2" from the crossmember and adding 2" to the spring/shock hats. Heidts had just come out with the bent strut to be mounted in line with the lower a-arm pivot. I drove it the first season with springs and shocks and went to Proshock coilovers the next year.

I set mine up by removing the spring and putting a 2x4 underneath from just inside one balljoint to just inside the other. I used a long piece of allthread to go through the a-arm and the strut arm. I built the bracket in pieces...rear first since I could slide the pattern on the all thread from the rear, then a slotted pattern for the front and then a gusset behind the bracket assembly. I also enclosed the outside of the bracket as much as possible. I then assembled the pieces derived from my patterns, checking the fit as I went.

So far the car has survived for 80,000+ miles with this system. Nothing has bent and none of the bracketry has failed. I upgraded to an ECI big brake kit 4 years ago.  Last year I had to get those doggone coilovers rebuilt...nothing last anymore - LOL. I've been very pleased with the front end kit though it wasn't low enough as designed. I asked Gary why he didn't offer a real low crossmember and he said he felt most guys would whine about it being too low. I told him what I did and he didn't take exception to it.

As a matter of course I check every nut bolt and bracket under the car every spring. The alignment doesn't appear to have "drifted" any and I haven't experienced any unusual tire wear, although I have worn out a couple sets of tires on it. And, I don't baby this car in the least, having done 157,000 miles over the last 28 years.

I have read all the input from the various members on this thread and can only offer that....your results may vary. Poorly designed and light weight brackets will fail eventually.

Charlie