New idea to stabilize rear cradle
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Last edited by FuzzyLog1c; 12-25-2012 at 09:43 PM.
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Yeah I read that and they were saying 2 part urethane is bad? If you look at the spec sheet it said something like 168hours till full strength. How is the other stuff cured? Moisture?
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That's an excellent question. I don't know the answer, and I can't find it yet. Presently, all I can say is that one advantage that a bushing fabricated in a factory or lab may have is that it is probably subjected to vacuum as it cures to remove air bubbles--both large and small.
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Yeah that is true, they do sell vacuum tables for making signs but the cost would never be worth it. If you were going make round bushings then you could buy round stock and turn them down in a lathe/machine them. I guess I get carried away trying to do and fabricate stuff myself. I have to make things a lot of times and get into the fabricator/builder mindset like hey I can do that. Its hard to know when to say when sometimes.
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As long as the new material does not damage the stock rubber, even if it fails it will just revert to the stock bushings. If you want a weekend project that may or may not work give it a go. For the price i think the revshift bushings are a better bet. But I don't think your idea is all that bad. The trick will be finding the best material for the job.
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Yeah that is true, they do sell vacuum tables for making signs but the cost would never be worth it. If you were going make round bushings then you could buy round stock and turn them down in a lathe/machine them. I guess I get carried away trying to do and fabricate stuff myself. I have to make things a lot of times and get into the fabricator/builder mindset like hey I can do that. Its hard to know when to say when sometimes.
#28
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Everything Fuzzylog1c said in this thread is accurate, so far. There are many different specifications to consider. The 2-part urethane sealant is not adequate. This is why those black aftermarket cts-v motor mounts are starting to crumble apart. There is a thread on here with pictures of what I am referring to.
No two polyurethanes are the same. Our polyurethane (the good stuff) consists of 4 to 6 different chemicals mixed together in very specific ratios. It is extremely involving and there is a lot to it. Vacuum chambers, curing ovens, inert gases, and specially designed mixers are involved. I can't get into the specifics because there are a lot of trade secrets that I can not talk about (seriously).
Those delrin inserts are machined from solid stock. The delrin stock is expensive and this is why they are $300. If you were to buy polyurethane stock then you would be in the same predicament as with delrin. It is also expensive for the stock. Not to mention that you would not know the properties of the polyurethane stock (aside from hardness) because the suppliers do not offer it. I can tell you that the cheapest supplier that I know of offering solid polyurethane stock would charge around $200 plus shipping for the amount of material needed to make the cradle bushings. You could always contact us, we can make you some nice chunks of polyurethane for less than $200.
Those delrin inserts are machined from solid stock. The delrin stock is expensive and this is why they are $300. If you were to buy polyurethane stock then you would be in the same predicament as with delrin. It is also expensive for the stock. Not to mention that you would not know the properties of the polyurethane stock (aside from hardness) because the suppliers do not offer it. I can tell you that the cheapest supplier that I know of offering solid polyurethane stock would charge around $200 plus shipping for the amount of material needed to make the cradle bushings. You could always contact us, we can make you some nice chunks of polyurethane for less than $200.
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#29
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No two polyurethanes are the same. Our polyurethane (the good stuff) consists of 4 to 6 different chemicals mixed together in very specific ratios. It is extremely involving and there is a lot to it. Vacuum chambers, curing ovens, inert gases, and specially designed mixers are involved. I can't get into the specifics because there are a lot of trade secrets that I can not talk about (seriously).
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#30
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And for ages, it's been sucking. It's too soft (55-60A) and it's not durable enough. It's got a narrow temperature range and insufficient resistance to moisture.
If window weld shears during a turn and you lose control of the car, that $110 you "saved" is going to look pretty stupid next to your totaled CTS-V and medical bills.
http://multimedia.3m.com/mws/mediawe...SevTSeSSSSSS--
http://multimedia.3m.com/mws/mediawe...SevTSeSSSSSS--
If window weld shears during a turn and you lose control of the car, that $110 you "saved" is going to look pretty stupid next to your totaled CTS-V and medical bills.
http://multimedia.3m.com/mws/mediawe...SevTSeSSSSSS--
http://multimedia.3m.com/mws/mediawe...SevTSeSSSSSS--
#31
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Sometimes ideas just come to you. Some are good and some are bad so I will bounce this one off the CTS-V community here. At work we use a compound to plug telephone cables which is basically a A/B urethane compound that hardens to for a air dam within the cable. Here is my idea; I looked on McMaster-Carr and I can order Shore 85A urethane casting compound for $33.33 for 25 cubic inches. What if I were to drop my cradle and build temporary forms around the cradle mount bushings and fill them with urethane? I cannot imagine why this wouldn't work. I don't want to hate on any products but $2-300 for spacers is a bit high. I am going to order some and give it a shot. I bet a piece of large exhaust tubing and some duct tape would make a nice form.
I did it. Spent $30 total I believe.
I shot some 3m window weld in the voids, let it dry in the same shape as the stock bushing, filed it down flat, then used the washers to sandwich it. With 2 washers it was way way too firm- so much so that all slack in the driveline whatsoever was sent upstream to the flywheel. The throttle response was great when you hammered it but in stop and go it was very hard to modulate...I came to the conclusion that there is slack in that cradle for a reason- to allow some of the movement of the diff and let you shift in peace. Ultimately I backed it down to one washer on top/bottom, and it was fine. Without having tried the aftermarket options, I feel it produced an adequate result with no add'l nvh.
I contemplated the spectres for many years, but I don't like how they and other aftermarket bushings basically fuse the cradle to the frame. The fill method kept those 2 parts (and vibrations) separate using the urethane as the buffer layer.
I know it may not the most effective solution but I was only looking to take out the side to side wiggle/slop in the rear end during relatively slow cornering, and it accomplished that nicely. I think the 3m stuff is 65a which was very similar to the stock rubber if not harder. If you're looking to eliminate wheel hop with cradle bushings, forget it.
I posted several of these pics before but I can't find the thread. sorry about the pic sizes. I've resized them using the photobucket editor, which works about 10% of the time.
sliced off the lips of existing bushings
![](http://i1027.photobucket.com/albums/y332/memphisctsv/IMG_0009.jpg)
![](http://i1027.photobucket.com/albums/y332/memphisctsv/IMG_0032.jpg)
templates
![](http://i1027.photobucket.com/albums/y332/memphisctsv/IMG_0051.jpg)
![](http://i1027.photobucket.com/albums/y332/memphisctsv/IMG_0060.jpg)
![](http://i1027.photobucket.com/albums/y332/memphisctsv/IMG_0057-1.jpg)
urethane dried but crude. I sanded them down nice and flat/uniform after these pics were taken
![](http://i1027.photobucket.com/albums/y332/memphisctsv/IMG_0221.jpg)
![](http://i1027.photobucket.com/albums/y332/memphisctsv/IMG_0212.jpg)
sandwiched with 2 washers. I eventually went to one, but never got more pics. You can see that the washers don't actually touch the cradle, but that urethane now fills the whole cradle void.
![](http://i1027.photobucket.com/albums/y332/memphisctsv/IMG_0243.jpg)
![](http://i1027.photobucket.com/albums/y332/memphisctsv/IMG_0265.jpg)
#32
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I assume that the original mount would hold (as best it can), but the filler material might suddenly split or shear under torsional strain caused by hard cornering (1.1G+). If that occurred, the rear subframe would suddenly shift, throwing the back end of the car wide. The natural reaction to that is going to be abruptly letting off the throttle, which may make the car want to swap ends.
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Well Cadzilla I guess my title "new idea" is blown out of the water. I guess the design difference of a solid rear axle and a independant are the reason the vibrations/harmonics are transferred. Cars with unit bodies have had their rear frame rails attached (welded) to the body/floors and rear suspensions mounted to them. Maybe 4 mounting points are not enough if you are trying to make a more solid connection to the car.
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Love the creativity of finding your own solutions, this is what makes the community on here so badass!
Personally a huge fan of RevShift mounts, affordable, durable and overall great company which is why I'll stick with their solution for the rear cradle. But that's just me.
Personally a huge fan of RevShift mounts, affordable, durable and overall great company which is why I'll stick with their solution for the rear cradle. But that's just me.
#35
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Love the creativity of finding your own solutions, this is what makes the community on here so badass!
Personally a huge fan of RevShift mounts, affordable, durable and overall great company which is why I'll stick with their solution for the rear cradle. But that's just me.
Personally a huge fan of RevShift mounts, affordable, durable and overall great company which is why I'll stick with their solution for the rear cradle. But that's just me.
#37
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And for ages, it's been sucking. It's too soft (55-60A) and it's not durable enough. It's got a narrow temperature range and insufficient resistance to moisture.
If window weld shears during a turn and you lose control of the car, that $110 you "saved" is going to look pretty stupid next to your totaled CTS-V and medical bills.
If window weld shears during a turn and you lose control of the car, that $110 you "saved" is going to look pretty stupid next to your totaled CTS-V and medical bills.
I assume that the original mount would hold (as best it can), but the filler material might suddenly split or shear under torsional strain caused by hard cornering (1.1G+). If that occurred, the rear subframe would suddenly shift, throwing the back end of the car wide. The natural reaction to that is going to be abruptly letting off the throttle, which may make the car want to swap ends.
#38
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And the glowing reviews of the Revshift bushings, post install, clearly indicate that replacing the stock bushings does something significant.
#39
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I assume that the original mount would hold (as best it can), but the filler material might suddenly split or shear under torsional strain caused by hard cornering (1.1G+). If that occurred, the rear subframe would suddenly shift, throwing the back end of the car wide. The natural reaction to that is going to be abruptly letting off the throttle, which may make the car want to swap ends.
Are the Revshift bushings better - YES
Is filling the stock bushings bad - NO
Will it last - To be seen...
Is it better than the Revshift bushings - I Doubt it, especially since you still have the soft stock bushing in there.
I think all Cadzilla is saying is that the cradle will still be in the car, there is physical restraint besides the bushings.
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This would be the pin in the haystack case. Worst case the rear would shift maybe 1/2" (and i really doubt you would get all 4 filled materials to fail at once. If you cannot handle that I would recommend not driving your car so hard, I would expect more issues from dirty roads than filling stock bushings.
But maybe I'm just paranoid.