ī58 Rear suspension "issues"

[frank58]

Anders, sorry, that picture came from one of our members "Travlin" whom I haven't seen in a while. He used the kits from Rareparts and posted pictures of the parts. Thats what I plan to use on my '58..... (when $$$ allows)

[Anders]

Anders, sorry, that picture came from one of our members "Travlin" whom I haven't seen in a while. He used the kits from Rareparts and posted pictures of the parts. Thats what I plan to use on my '58..... (when $$$ allows)

Thatīs cool, because it gave me the idea to ask them If Iīm lucky, they know and hopefully give me an answer when they come to work after the weekend.
I also sometime wonder what happends to Dear Travlin. I still laugh when I read what he wrote to his pictures. "Houston, we have a problem!" is a classic ( http://www.freewebs.com/squarebird/roof.htm )
You donīt happend to know how long your ( carīs.. ) sleeve is?

[Anders]

Thanks to Carl ( partsetal ) I now know that the bolt seems to be tighten quite alot. This means the rubber have to be soft. It most probably also means that my sleeves are to long and the ones from Rareparts might be a better leingth. Weīre getting there

[GTE427]

Dave,

Your box (parallelogram) is a great visual in this case. Each corner of the box must pivot for the suspension to travel. Anchor one corner and it will lock the box and there will be no movement.

In your diagram points (A) 5549, (C) (D) 5500 are obvious pivot points, not so obvious is (B) 5555. See my attached red-line. In order for 5555 to pivot, bushing 5537 has to allow vertical travel. If the spacer 5540 is too long or this point is bolted tight, this corner is anchored and the suspension binds or locks the box.

This was Anders orginal observation, too tight and there's only 2" of travel, the looser he makes it, the move travel he gains. Make sense?

Hopefully Anders can find the infromation he needs from Rare Parts.

EDIT: these bushings 5537 are actually acting like coil springs, in that case the spacer lenght should not be as big a worry, if the bushings were reproduced, maybe the hardness of the bushing is too great, like have too high a spring rate that they can't be compressed. Looking at the photos Carl supplied, that looks more like the bushing height I'm use to seeing, I was surpised to see the lower bushing listed as being 2" tall, in Carl's photos, it's been compressed quite a bit.

[simplyconnected]

...Anchor one corner and it will lock the box... ...If the spacer 5540 is too long or this point is bolted tight, this corner is anchored and the suspension binds or locks the box... ...these bushings 5537 are actually acting like coil springs...

Nice job on the drawing, Ken. I would really like to see a side-view of the pivot points. After re-thinking this system (in my long post), I totally agree with you.

5555 is a pillow block fixed to the lower arm (that the top portion pivots on). That's the key. In your drawing, it is noted that all the U-bolt and cradle parts are part of, and fixed to, the axle assembly.

Three mounting points on the lower arm will stop all pivoting. If the back rubbers are torqued tight and the wheel hits a bump or hole, the upper arm (C-D) will tend to snap off.

But, if we allow space between the rubbers, they will 'slap' and cause noise (in both directions). I'm still not comfortable with the center sleeve sliding in the lower arm hole steel. That's just plain wrong, and that is what messed me up.

But you're right, Ken... if the rubber assembly is designed to limit motion, they just transfer torque to the adjacent sides. That's wrong, too.

If this were my car and I HAD to live with this setup, I would omit the rubber assembly altogether and run with nothing back there. I do not see what purpose the rubber serves, that the shocks don't already cover. - Dave

[Anders]

Nice job on the drawing, Ken. I would really like to see a side-view of the pivot points. After re-thinking this system (in my long post), I totally agree with you.

5555 is a pillow block fixed to the lower arm (that the top portion pivots on). That's the key. In your drawing, it is noted that all the U-bolt and cradle parts are part of, and fixed to, the axle assembly.

Three mounting points on the lower arm will stop all pivoting. If the back rubbers are torqued tight and the wheel hits a bump or hole, the upper arm (C-D) will tend to snap off.

But, if we allow space between the rubbers, they will 'slap' and cause noise (in both directions). I'm still not comfortable with the center sleeve sliding in the lower arm hole steel. That's just plain wrong, and that is what messed me up.

But you're right, Ken... if the rubber assembly is designed to limit motion, they just transfer torque to the adjacent sides. That's wrong, too.

If this were my car and I HAD to live with this setup, I would omit the rubber assembly altogether and run with nothing back there. I do not see what purpose the rubber serves, that the shocks don't already cover. - Dave

Weīre talking about what might happend at work today, and we guessed that it might make the tire to jump on heavy acceleration or sudden stop. The shocks and springs helps of course, but there is no way Ford put this on if they didnīt needed it. No matter how stupid it looks.
A little comment to you guess what happend if it is too tight and the car hits a bump or a hole, the control arm donīt snap, but all forces goes strait to the front position bolt and the chassie, and that is just what have happend in the past. Interesting is that the bolts seems to be bulletproof as they are still strait, and the threads works like new. And they ARE original. On booth sides of this holes, someone in the past have velded bigger square "washers" to the subframe as extra streingth and support. Original is smaller round ones. Upon that, on one side, the bolt of the inside of the subframe, got loose, and took a piece of the frame in the process. Strong forces, no doubt.

Now today I vent to the place who helped me with the vulcanisation of the upper control arms bushings and talked about making new isolators for the rear. The softest they can come up with is 35-40 Shore. I donīt know if these are to soft or hard, but I am thinking of let them make two set, so I can "take out parts" with waterjet in one set. That way, I would get a even softer pair to play with.
The big deal is that I now finally understand the whole system and know where to fine tune the whole "thang"

Rare Parts did come back today, but only with a picture of the parts, not with and information regarding the hardness of the rubber. But I sended that question back, so maybe tomorrow?

Love you guys! You are a great support!!! My fellow "US-old-car friends" at work, who owns Babybirds, Torinos, Rancheros and even Chryslers envy me alot because of this forum. I like that


Some "before pics" showing how it looked before when the bushings was all gone in the control arms. You see how the lack of bushings took up the play... Note one of these "nests" I have all over the car. Found one in the front suspension, and to in the rear suspension just 2 weeks ago. So far the total is up at 15 or so by now... Further down, The control arms before, and after.

[Anders]

Here is a picture showing how it looks. You see without the bolt and isolators the whole rear axle drops quite a bit. I guess the bolt and nut at least prevent the rear axle to drop all this... As it looks here, I can easy push it up against the exhaust pipes.
The smaller isolator ( rubber ) is located above the trailer arm ( black ) and under the rear axle part that is not painted here, and the thick under the black arm. So they kind of takes up the "end" of the movement. The upper for when the car bumps down, and the lower, when the car goes up.

[redstangbob]

The pictures sure help. It looks like quite a contraption , but there has to be some way for the pinion angle to be maintained through the axle travel. The lower arms move in an arc, I don't know why they didn't set the upper links in such a way to keep the diff at the right angle with a loaded trunk or hitting a bump. Maybe it was supposed to be smoother or quieter, I can see why it only lasted a year. Good luck Anders, the prices on that stuff looks pretty serious

[simplyconnected]

Anders, I feel your pain and I want to help as much as possible. Thank you for the good pictures. Now, let's talk:

We have been making cars for a very long time, and I always beg the question, 'what do modern cars use?' I do not limit this question to one brand, but I look for the very best solution.

Your suspension was installed for one 're-designed' model year, then it was dropped for years and for good reasons. We know that auto manufacturers buy engineering for 'specialty' applications, and I believe this was the case with the '58 Thunderbird.

Back to the problem. ??? What car with rear coil springs, uses 'dampers' like yours? After all these decades, I don't know of any. The rear brakes don't do much braking (maybe 20%), and the car is 1,000 pounds heavier than the '57 with not much more HP, so no wheel hop.

It makes sense that all suspension should freely pivot and not exert any unnecessary binding forces on the mounting bolts (perches). This isn't a matter of 'looks' but of function. Apparently, Ford engineers found this system to be a bad idea, and all of the competitors avoided it. - Dave

Edit: I forgot to say; usually your shock absorbers and frame bumpers limit axle travel.

[Anders]

Anders, I feel your pain and I want to help as much as possible. Thank you for the good pictures. Now, let's talk:

We have been making cars for a very long time, and I always beg the question, 'what do modern cars use?'

Canīt resist, but isnīt the answer: Spring coils? Only old timers and trucks use Leaf........
We have all learned how it works by now. The only thing that I donīt know is the length of the sleeve, even if 2 1/2" seems closest. And we donīt know the Shore. As soon as we know that, we are home I beleve, as I will be very careful how I set up the ther suspension by the bolt.
I guess most never figured it out and just tighten it, and came out with other problms, only later, so they maybe not did the conclution why....
I sure agree with redstangbob, that the geomerty with all pivots points sucks. Big time. Someone didnīt do there math

[simplyconnected]

...You see without the bolt and isolators the whole rear axle drops quite a bit. I guess the bolt and nut at least prevent the rear axle to drop all this...

You are showing me an axle with no shock absorbers and no springs. Of course it drops, because it should (just like a modern axle). Restricting movement and binding, should not be done between the lower arm and the axle. Your shock absorbers hold up your axle. Connect your shocks and let's see how far it drops.

I also see a rubber bumper on your upper frame member. Without springs, your axle should have freedom to reach that bumper.

[Dakota Boy]

This is really cool to see actual photos of this stuff. The '58s were certainly a rare design as far as the rear suspension is concerned.

Where your upper control "arm" or "rod" attaches to the frame... on my car there was a "torn spot" there on the right side. (I welded a stainless patch over that old injury this past winter. I have leaf springs on my '58 and dont need that mounting hole anymore.)
Based on my findings while lying on my back under the car for most every weekend this winter, I'd say that my car suffered a fender-bender on the passenger side at some point in the past.

She tells no tales of her past though, no matter how nice I speak to her....

Sorry to high-jack your thread with my non-contributory comments!

[Astrowing]

Do we have the dimensions of all the bushings tabulated somewhere from all these pictures? Are the upper arms and control arm pressed in?

[Anders]

The bushings in the control arms are "vulcanizied". Thatīs the most English version of the Swedish word "Vulkaniserad" I know...
The rubber is cocked on the centre metal bushing and then pressed into the control arm in a machine with a few tons of pressure. Itīs as original you can do it.
All other bushings is replaced by polyrethane bushings, that looks like "hats" and are pushed in from each side.

[Astrowing]

They are pressed just like front-end parts. Thanks. Do you have dimensions on the upper and lower arm pivot bushings? How about the control arm? Metric is fine. I can convert.