Rear cradle alignment procedure

Suspension, brake, and hydraulic/electric steering discussion.
kevink
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Rear cradle alignment procedure

Post by kevink » Wed Apr 18, 2018 4:40 am

When I had my cradle down, I noticed that the rear cradle bushings had oval holes that accept the pins that point down from the body. The ovals were oriented from left to right, allowing for quite a bit of side to side cradle movement before the bolts are tightened. The O.D. of the pins on the body are the same as the width of the oval hole in the bushing, so there is no front to back adjustability. Is there an official cradle alignment procedure for centering the cradle under the body?

smwalker
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Re: Rear cradle alignment procedure

Post by smwalker » Wed Apr 18, 2018 7:08 am

Does not seem to be any specific instructions or steps to take during install. I would imagine it is just there to take up for differences in the stamping.assembly process. All other adjustments can be made in the arms to get everything straight. That being said shoot for the center of the pin. WHen I installed mine I was just happy to get it up there and the bolts all lined up. That was good enough for me!

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Steve Walker
Azusa, CA
'11 PPV 9C3 Huron White

CrashTestDummy
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Re: Rear cradle alignment procedure

Post by CrashTestDummy » Wed Apr 18, 2018 1:56 pm

So what happens if you have an unsuitable frame support, but you're using it anyway? Are you not allowed to remove it when you put the car back in service?? :lol:
Gene Beaird,
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kevink
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Re: Rear cradle alignment procedure

Post by kevink » Wed Apr 18, 2018 4:14 pm

Thanks, Steve. There is a lot of side to side movement of the cradle, which was my concern. Sure, an alignment can get the wheels straight, but an alignment won't center the wheels under the car in relation to the quarters or wheel wells. This issue is not a problem for most people, only those trying to stuff the most tire possible under the car.

I also thought that the holes in the bushings were ovaled to allow for variances in construction of the cradle and body, but I measured mine and the body pins were exactly centered in the ovals. That does not prove anything, I know, but it's something to think about. I ended up making aluminum sleeves that fit inside the bushings to locate and solidly lock the cradle to the body and allow for no cradle movement at all. I will take some measurements after I get tires mounted and the car aligned to make sure everything is centered under the car. I just thought there might be an official alignment procedure. I'm kind of surprised there isn't due to the slop designed into it.

s/c'd cav
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Re: Rear cradle alignment procedure

Post by s/c'd cav » Wed Apr 18, 2018 4:59 pm

the gto was the only vehicle i knew that used a alignment tool for the cradles , since the G8's ive never seen or heard of any such tool

smwalker
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Re: Rear cradle alignment procedure

Post by smwalker » Wed Apr 18, 2018 10:30 pm

kevink wrote:I ended up making aluminum sleeves that fit inside the bushings to locate and solidly lock the cradle to the body and allow for no cradle movement at all.
I asked on the SS fourms about mods to do while the rear cradle was out and someone (maybe navy lifer) mentioned to install new rear cradle to body bushings and they pointed me to a company that made solid aluminum ones (little pricey). I wonder if they also eliminate the oval gap for a more solid fit.

See if I can find the link:
http://pegasus.corecommerce.com/GTO-G8/ ... minum.html" onclick="window.open(this.href);return false;
Steve Walker
Azusa, CA
'11 PPV 9C3 Huron White

kevink
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Re: Rear cradle alignment procedure

Post by kevink » Wed Apr 18, 2018 11:01 pm

smwalker wrote:
kevink wrote:I ended up making aluminum sleeves that fit inside the bushings to locate and solidly lock the cradle to the body and allow for no cradle movement at all.
I asked on the SS fourms about mods to do while the rear cradle was out and someone (maybe navy lifer) mentioned to install new rear cradle to body bushings and they pointed me to a company that made solid aluminum ones (little pricey). I wonder if they also eliminate the oval gap for a more solid fit.

See if I can find the link:
http://pegasus.corecommerce.com/GTO-G8/ ... minum.html" onclick="window.open(this.href);return false;

The Pegasus bushings take some side to side slop out but add front to back slop since they have a round hole that is 0.125" larger than the body pin.

Navy Lifer
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Re: Rear cradle alignment procedure

Post by Navy Lifer » Thu Apr 19, 2018 12:16 am

kevink wrote:
kevink wrote:I ended up making aluminum sleeves that fit inside the bushings to locate and solidly lock the cradle to the body and allow for no cradle movement at all.
The Pegasus bushings take some side to side slop out but add front to back slop since they have a round hole that is 0.125" larger than the body pin.
Not sure I understand this--what are you using in the cradle--original rubber bushings? Your sleeve went into the end of the bushing (shown in 2nd picture) to engage where--or is it that you're reducing the hole size to make a close fit with the bolts?

Drawing or picture of what you did would be helpful--is this a part that is configured to do what the polyurethane inserts offered through several sources are supposed to do?

The bolts are shown to be torqued to 148 lb/ft--and the cradle/crossmember still has "slop"???
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mount3.JPG (37.29 KiB) Viewed 1951 times

kevink
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Re: Rear cradle alignment procedure

Post by kevink » Thu Apr 19, 2018 1:26 am

Navy Lifer wrote:Not sure I understand this--what are you using in the cradle--original rubber bushings? Your sleeve went into the end of the bushing (shown in 2nd picture) to engage where--or is it that you're reducing the hole size to make a close fit with the bolts?

Drawing or picture of what you did would be helpful--is this a part that is configured to do what the polyurethane inserts offered through several sources are supposed to do?

The bolts are shown to be torqued to 148 lb/ft--and the cradle/crossmember still has "slop"???
We are sort of talking about two different things here now that Steve brought up Pegasus bushings, which I happen to be using. My aluminum sleeve presses into the top of the rear Pegasus bushing to take up the space between the body pin and the bushing. It makes the cradle fit tight with no movement in any direction. Without the sleeve, there is cradle adjustability, which was the original reason for this thread on cradle alignment. I'm sure most people would never go through the trouble of machining sleeves like mine, so I'm not sure how deeply we need to get into it here.

What I did is nothing like the aftermarket inserts that are used with stock bushings. Those aftermarket inserts do not do anything for the play present between the factory body pins and the rear bushings.

The factory bushing has play side to side because it is ovaled out larger than the body pin as described above. It's not drastic, but it is definitely designed into the bushing. There is no slop with the bolts tightened. The cradle can be moved freely side to side before bolting it down to whatever location you chose.

The photos you posted are of a front cradle bushing. They are not the ones that fit around the body pins, locate the cradle, or have ovaled holes. The rears do all of the locating work on these cars. Again, the adjustability of the rear cradle using factory bushings on these cars is slight and only in the side to side direction. With the Pegasus bushings, the adjustability is more than with stock bushings and it is in all directions unless you make sleeves to tighten the fit between the body pins and bushings.

Navy Lifer
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Re: Rear cradle alignment procedure

Post by Navy Lifer » Thu Apr 19, 2018 2:00 am

smwalker wrote: I asked on the SS fourms about mods to do while the rear cradle was out and someone (maybe navy lifer) mentioned to install new rear cradle to body bushings and they pointed me to a company that made solid aluminum ones (little pricey).
yes I did....
Navy Lifer;3309986 wrote:Steve, as long as you're spending money....

2. Solid crossmember/cradle bushings (I don't think there's anything to gain with bushing inserts with VF/WN cradle bushings, which are already "improved" from VE/WM) - Pegasus lists them for G8, should be direct fit to PPV/SS

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