Rear suspension mount cross-member broke! - Impala Tech
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post #1 of 17 (permalink) Old 04-29-2018, 09:35 PM Thread Starter
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Rear suspension mount cross-member broke!

Dadgummit this car is one challenge after another.
Heard some random, minor clank/clunk sound going to and from a car show last weekend.
Couldn't find anything on my own when on the lift. Every nut and bolt was tight and manhandling things couldn't reproduce the noise although the car would bounce but with no noise.
I jacked up the car so the rear end would hang down and had a friend listen while I started the engine and engaged the clutch multiple times.
We found this....




In that last picture, a friend noted that you can see some surface rust on the weld-line where it had been cracked at the leading edge for quite some time. That welding doesn't looks so awesome to me either.
Will clean it up and see if I can get more 'forensic data' before we fix it.
It doesn't even look like the bottom edge or front lip (not seen) got any weld at all.


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HOW A NOVICE REBUILDS A 66 IMPALA CONVERTIBLE:
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Last edited by BA.; 04-29-2018 at 10:56 PM.
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post #2 of 17 (permalink) Old 04-29-2018, 09:45 PM Thread Starter
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It may have been cracked or broke when I bought the car.
When I got it the control arm had been ripped from the same crossmember STILL BOLTED. A friend and I welded it back in and added a strengthening over-plate on the front side.
It may also have happened or gotten worse when I broke the Muncie, or the rear end. :-)
Or, maybe it helped the bearings wear out that caused the demise of the Muncie.
Even on the lift, just engaging the clutch with a tiny bit of throttle my friend could see the rear end move fore and aft a little.

We were wondering if this may have happened or gotten worse because I haven't put in the second upper control arm yet. I drive it hard. The old 10 bolt only had the single passenger side upper CA.
I've heard the experienced guys on this forum mention that higher horsepower cars with the 12 bolt usually had two uppers so I bought a second adjustable upper and haven't put it in yet.
Maybe manual transmissions in a 4000 pound car twist things up a little when there's only one upper control arm?




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post #3 of 17 (permalink) Old 04-29-2018, 09:48 PM Thread Starter
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I should also note that these pictures are with the rear end hanging free From our test.
When sitting on all four tires that gap closes to about 1/16 to 1/8 of an inch.

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post #4 of 17 (permalink) Old 04-30-2018, 02:28 PM
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I feel for you. Did similar damage to my Impala. I replaced the factory rubber bushing four link with an aftermarket adjustable four link from S&W. Noticed that by the time it ripped off I had sheared through the rubber control arm bushings cutting them up and allowing the pieces to fall out. This resulted in a bolt rattling around in a very big hole, which accounts for the noise I heard prior to failure.

I had to machine my own aluminum body bushings to get rid of the rubber as the frame flexing was cutting up the rubber. With solid mounts the body stiffened up the frame enough to allow me to easily lift the front wheels, rather than twisting the frame up.

Have to keep in mind rubber was used by the factory engineers to reduce road noise and to please the female owners that prized a smooth ride over being able to cut a corner. With solid body mounts and big sway bars I could drift my Impala around interstate exits at a over a hundred miles an hour (that is what I was doing when I hit a pot hole and ripped the sump off my oil pan).

Not every one drives like me, but I am an acceleration junkie. Blame my little Douglas A4 Skyhawk for addicting me g-forces. Acceleration wasn't it's thing (I was flying the earlier A4B that had a puny power plant compared to the final version) but it could turn on a dime delivering an easy six g's at 520 knots indicated.

Big Dave
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post #5 of 17 (permalink) Old 04-30-2018, 04:45 PM Thread Starter
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So Big Dave, you did that to a 4-link setup eh? Were you running sticky tires too? (I am running basic street tires, Nitto 420s.)
And here I was afraid that I might have aided and abetted my situation by only running a single UCA because I've been too busy to get the drivers side UCA added in.

HOW A NOVICE REBUILDS A 66 IMPALA CONVERTIBLE:
http://www.impalas.net/forums/blog.php?u=1432
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post #6 of 17 (permalink) Old 04-30-2018, 06:40 PM
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Torque breaks parts. More torque you make the sooner you discover your weakest link.

With my old heavy car (was 1,200 pounds heavier than my old race weight Nova bodies) I discovered that even with a 10.5 inch slick I couldn't get any decent traction. It took a 14 inch wide slick to hook up, which resulted in flattened exhaust tips and a lot of sparks as I unloaded the tires when the rear bumper hit the ground that caused the car to drop the front end violently on to the track (more sparks as I scraped the pan and headers) after getting six foot of air.

I like big, big blocks with lots of stroke (running 4.375" to 4.750" depending upon final displacement) that generate parts breaking torque in spades. Having twisted, or broken just about every part on a car over time I have learned how to pick hefty, hefty, heavy duty parts to live with the diesel engine levels of torque that my normally aspirated engines produce. Most of which started life on a medium duty diesel powered truck, before I grabbed them up out of truck salvage yard and modified them to fit my car (most Ford one ton pick-ups have a 6.7 liter diesel engine rated at 750 foot pounds of torque. Add a turbo charger and you are over a thousand foot pounds from the factory with parts designed to live at level of power for several hundreds of thousands of miles. Hence my love of the Dana 60, six inch drive shafts with 1450 universal joints and a tranny that can handle the load (in my case I use a GM based 4L80 or a 6L90).

I foolishly thought the factory four link would handle the power because it was used under a Chevelle with a 460 horsepower LS-7 BBC. I learned other wise by abusing the suspension by asking it to do more than it was designed to handle.

I didn't think that full wheel covers peeled off while driving around on city streets as observed in car chase scenes in the movies. After I replaced my second set of lost wheel covers (they are hard to find at three in the morning on a dark industrial park street) I switched over to Heavy Duty Police Car ventilated steel wheels because the stockers where bending under (deforming); popping off the wheel covers as I turned hard throwing my cars weight around.

This is why I tell everyone to try and find a used up cop car in a junk yard. It is the only source of performance parts that are a direct bolt on for these B-body cars that allow you to find SS level (F-41) suspension parts, as there wasn't a F-41 offered for the Impala with an SS car with the exception of the factory built 427SS option that dropped an L-88 427 BBC into a police car (9C1) and added an SS interior (bucket seats and trim, with a one of a kind hood).

Big Dave
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post #7 of 17 (permalink) Old 05-01-2018, 11:38 AM
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BA, good documentation on the issue... my concern other than the crack is why it pulled so far apart?

Off discussion question... I'm documenting my RestoMod build at this link:http://www.impalas.net/forums/8-rest...d-end-end.html


How do you get your pictures to show in the thread, all I get is links and pics at the bottom in Thumb nails???

Thanks Mark
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post #8 of 17 (permalink) Old 05-01-2018, 11:58 AM Thread Starter
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Quote:
Originally Posted by mkassab View Post
BA, good documentation on the issue... my concern other than the crack is why it pulled so far apart?


Thanks Mark
Good eye Mark. Sorry, I should have mentioned that in those pics the rear end is hanging free because I had the frame on jack's so I could start the car and engage the clutch (on a 4 post lift) while a friend looked/listened.
When sitting on all four tires, the crossmember closes up to about 1/16 of an inch gap and I was able to pull it tight with the adjustable upper control arm.

Will have to answer the other question later, perhaps with a screenshot.

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HOW A NOVICE REBUILDS A 66 IMPALA CONVERTIBLE:
http://www.impalas.net/forums/blog.php?u=1432
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post #9 of 17 (permalink) Old 05-01-2018, 03:14 PM Thread Starter
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Quote:
Originally Posted by mkassab View Post

How do you get your pictures to show in the thread, all I get is links and pics at the bottom in Thumb nails???

Thanks Mark


I believe it's just the difference between when I am uploading a picture from my phone using the Tapatalk app, or when I'm on my PC and using the Impalas.net site tools for picture uploading.

I noticed that when I use Tapatalk, that the picture seems to still be held in the Tapatalk content-delivery-network within my threads. So, that is in essence, an "externally hosted" picture.

When we use the built-in Impalas.net tools to "manage attachments", the picture gets hosted locally at the Impalas.net server and by default, the thread shows those mini-thumb-nails that have to be clicked on to get the (resized) full view.

Externally hosted pictures, whether they be via Tapatalk, or a Godaddy server location, or any Photo-hosting business, those will all get the full picture display like you noticed from me in this thread.

By the way, since you like pictures, take note that there are ultimate storage limits depending upon when membership you've selected. At some point - you may reach your limit and either need to remove very old ones, or host externally, or compress them before posting, etc.

HOW A NOVICE REBUILDS A 66 IMPALA CONVERTIBLE:
http://www.impalas.net/forums/blog.php?u=1432
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post #10 of 17 (permalink) Old 05-01-2018, 03:32 PM
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So BA, when you use Tapatalk, do you then set the URL to look at the picture vs the upload option?

Thx Mark
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post #11 of 17 (permalink) Old 05-01-2018, 03:44 PM Thread Starter
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When using Tapatalk it looks a little different.
I just hit this orange circle to Reply and this gray box to attach photos.
The app takes you to your phone's photo gallery and you just select the ones to upload .



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HOW A NOVICE REBUILDS A 66 IMPALA CONVERTIBLE:
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post #12 of 17 (permalink) Old 05-01-2018, 10:04 PM Thread Starter
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On the road to recovery.
Figured I would post up a shot of the work in progress.
The first picture is pre - weld. Cleaned up, mated as close as could be and a little grinding to increase the surface area at the crack.

A friend did this first main weld for me. I'll do the 3" vertical part of the crossmember and then weld in a strengthening plate or 2 across it all. Will probably put a small plate on the driver side as well.
Then I'll add in that 2nd upper control arm from Hotchkis! Boom!

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HOW A NOVICE REBUILDS A 66 IMPALA CONVERTIBLE:
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post #13 of 17 (permalink) Old 05-02-2018, 08:02 AM
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BA, when you add the second upper control arm to the drivers side, where will you get the axle brace part from, or will you fabricate one? I think this is a great idea and want to do the same on my build while I have everything apart.

Thanks Mark
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post #14 of 17 (permalink) Old 05-02-2018, 08:44 AM Thread Starter
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Fortunately this particular 12 bolt unit already has that 2nd axle mount bracket already on there. And on the sub-frame, the 3 holes are already there as well.
I think it's common to expect the 12 bolt rear-end to have that already in place. (but not generally on a 10 bolt rear-end)

I had busted my stock 10 bolt behind the 383/Muncie so an upgrade was in order. I found this 12-bolt in a local junk-yard, supposedly from an Impala, and I had the posi-unit, gears and seals/bearings all replaced before putting it in this car.

HOW A NOVICE REBUILDS A 66 IMPALA CONVERTIBLE:
http://www.impalas.net/forums/blog.php?u=1432
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post #15 of 17 (permalink) Old 05-02-2018, 08:53 AM
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Thx BA

Mark
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post #16 of 17 (permalink) Old 05-02-2018, 11:03 AM
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Just an FYI, I found everything I needed at Summitracing.com... i.e, axle bracket, etc. to add the drivers side upper control arm. I'll cover the installation on my build thread

Mark
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post #17 of 17 (permalink) Old 05-15-2018, 12:43 AM
 
 
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[QUOTE=mkassab;216426]BA, when you add the second upper control arm to the drivers side, where will you get the axle brace part from, or will you fabricate one? I think this is a great idea and want to do the same on my build while I have everything apart.

Thanks Mark[/QUOTE)

Man I can't believe you guys really pour the coal to your cars, amazing.
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