Good Shocks to use on Classic Mustang - Part 2: Suspension Bind?

[oz]

Greetings,
A couple of weeks ago I posted a thread about good Mustang shocks and it turned into a thread on diagnosis of a handling problem I have.
http://forums.stangnet.com/showthread.php?t=521479

One possibility was suspension bind. This is how I described it:

"The problem I have is most noticible when cornering at speed (like a highway off ramp). The front of the car seems to understeer upon entering the corner and then the outside corner quickly drops and and the car starts to turn hard (near oversteer)."

I now have the springs, the sway bar, and the shocks off (and the car is supported by the frame) so the suspension is free to move. What I found was that the suspension moves smoothly but as the suspension is pushed up toward the bump stop, it gets progressively harder to lift. I think the strut rods are exerting a force on the control arm such that it makes it difficult to lift (since the distance to the strut rod mount gets longer and binds the lower). Is this normal? When I redid the suspension 8 years ago I used urethane bushings (including on the strut rod). I cranked down the strut bushing nuts (fore and aft) to pinch it down pretty tight after it was aligned too since they seemed loose after the alignment.
I am going to change the shocks regardless but should I also install rubber strut rod bushings? Would greasing them help (the one strut rod bushing creaks like crazy)?
Is there something else I am missing?

THANKS!

 

[Route666]

That is what will happen oz, it's a bar squeezing on a bit of rubber (or worse polyeurethane) to hold it in place. You can get rod-end style strut rods that should eliminate that bind, but will still cause some bind at the extents of the suspension travel because they don't stretch, but this should be negligable.

Since you are using the poly bushings, I would suggest at least changing them back to rubber, it may make handling a bit more loose, but your suspension travel should be a bit more free and you won't be stressing the rods as much. It seems if you're finding the rod binding causing trouble while driving you must be going pretty hard on it, and that will stress the rods until they snap. You don't want to be going hard and have a strut-rod snap.

I'm all for poly except for the strut rod bushing. Oh and lateral links on 4-link. I've snapped both of mine, about 6 months apart because they had poly bushings. I replaced them with rubber and all is fine. I did all that with the brute power and mass of a 2500lb 1.6L...

 

[jikelly]

I wonder if I should change mine back also. I have a 73 mustang and I am having steering problems which I think might be due to my strut rods binding when I go over bumps. When my girlfriend asked me what I wanted for Christmas I should have said a set of those really expensive rod end style strut rods. Frankly I think that would be taking advantage of her, and besides there is no way I could afford to give her a gift of equal value.

 

[Route666]

I would, if it were me. My research and reasoning have come to the conclusion that the strut rod is meant to rotate, and only that, and that is EXACTLY what a rod-end type strut rod does.

I'd also put boots over the rod ends and fill with grease if possible.

 

[oz]

Is this what you mean: http://www.globalwest.net/mustang_1964 -73 catalog.htm#Adjustable strut rod kits

- a ball and socket type attachment to the body?

THANKS

 

[66P51GT]

They are also available from Street or Track.
http://www.streetortrack.com/adjustable-strut-rods.asp

 

[Route666]

Yep like the Global West or Street or Track. TCP offer them as well. TCP ones are $339 according to their website, could be different in the catalogue, and availibility might be scarce. GW are the most expensive and apparently have a more secure way of aligning and securing the right plane of movement, but the product images on the site aren't confidence inspiring unlike the clearer pictures of TCP and SoT.

 

[Tubo(2-bo)]

The 67-72 Mustangs, have a longer strut rod than the 65-66's. This was done when Ford widened the track on the then new cars. The length was added in the threaded portion of the rod. When Poly bushings are used, they hold the strut rod so firmly (this is in the 67-72's) the rod is flexed, during suspension travel, at the weakest point=junction of threraded & unthreaded section. Over a period of time metal fatigue can set in, and a failure occour.
There are a lot of stories about "Ploy broke my strut rod" If you check, the stories are about 67-72 cars.
The 64.5-66 Mustangs ARE NOT succeptiable to this happening. The flex happens over the length or the rod , not focused on the weakest point.
While maybe not a good solution for 67-72 Mustangs. Polyurethane strut rod bushings are a very good COST EFFECTIVE piece to use on the 64.5-66 Mustangs.
Articulated strut rods, are a much better choice, At a MUCH $HIGHER$ price. $15 vs $175-$325. What does your budget tell you?

 

[rufusbooth]

Not to add any flames to this conversation Tubo but unfortunately I have seen the strut rods break in the same location on the 65-66 cars. Unfortunately it was on my vehicle and I was running poly on the strut rods. Granted the 67-x cars are more vulnerable to this issue due to their increased leverage (I.E Longer rod) but the 65-66 system can still fail. My personal opinion (and it is just an opinion) is that the strut rods should never have any poly at all. Rubber or an articulated strut rod will be the only options on my 65 vert.

Now may I also add another possibility to your handling problem? You may be looking at a bump steer issue. You said you noticed it most when turning into a corner. You did not mention how the car feels when going over a large bump at speed. For example, a set of high crowned railroad tracks that would use about 80% of your suspension travel would be a good test. If your car tends to swerve a little or feel unsettled bump steer may be the problem. In extreme cases the car will basically steer its self which will raise the hair on the back of your neck in a hurry J

This is a link to a fairly good article outlining the test and repair of bumpsteer problems. Since you have the springs and shocks out right now you might want to check that bump steer out.

http://www.ffcobra.com/FAQ/bumpsteer.html

 

[oz]

I removed the strut rods (with urethane bushings) and viola, the suspension moves smoothly. I have ordered a set of rubber bushings but I don't plan to change the rods. The rods were new in '96 and I honsetly have probably only put 500 miles on the car since then.

I never noticed a problem over bumps or railroad tracks before, only corners. The stock suspension geometry is maintained in my setup (completely rebuilt/replaced in '96, original front springs) so I wouldn't really expect any more bump steer than when the car was new.

Hopefully the bushings and KYB Gas Adjsut shocks will make a difference.

THANKS for all the great help!!!!