New idea to stabilize rear cradle
12-26-2012, 08:01 PM
#41
^ I know what you're describing but I don't think it's due to the cradle bushings kicking out. I think what's happening is the wobbling bushings walk the car out when it's at grip threshold. At least that'su experience. It's not a sudden walkout but more of a shimmy.
12-26-2012, 08:11 PM
#42
I'm describing a sudden walk out. Like putting a couple of wheels over an uneven road where one side is freshly paved and the other isn't.
12-26-2012, 09:04 PM
#44
The stock bushings merely keep the cradle somewhat in check on hard turns, that's why it's wishy washy unless you're pulling 1g. (you'll feel the rear sway and "set", that's you getting past the lip and using the actual bushing). The frame is formed into 'sleeves' that the long bolts pass through, and the bolts have washers on the bottom that press against the sleeve. (torqued very high) The circular cradle mounts never actually touch the frame. If they did you'd have alot more rear end and drivetrain noise. At rest and while just puttering along, the only contact is made by a 1/8 inch lip of the existing bushing which isn't even as wide as the pieces of bushing we're calling a bushing.. What I did took out the slop, period. I'm telling you now, unless you're going for all out stiff as hell up your butt jobu handling, filling those voids and adding washers is enough. You could also use a higher durometer material for an even stiffer effect.
I concede that I wouldn't do what I did as an all out 'replacement' for stock bushings even though the material can't just fall out, and under even the most extreme conditions wouldn't deteriorate to the point where it would fall out (not this 3m stuff anyway). I only filled the existing void of the stock bushings with a fairly equal durometer material.
I also am comparing the result of this to the traditional cradle bushing inserts like the GM crap and the much more beneficial spectre bushings.
I hadn't looked until now, but these revshift bushings are completely different than any aftermarket soultion thus far and replace the old bushings instead of being "inserts"...that's going to be a BIG difference. Top to bottom poly AND they connect the frame with the cradle? They are also noticeably stiffer than stock at 80a and 95a. I would say stock is probably 70ish?
Alot of your stock forgiveness in handling is going bye bye as well. This will be like adding a 2" rear sway bar...you will definitely need to relearn the rear's characteristics after installing so you don't do a 180 on your favorite turn to the grocery store..
Last edited by Cadzilla; 12-26-2012 at 09:38 PM.
12-26-2012, 09:49 PM
#46
12-26-2012, 10:01 PM
#49
Ok let me rephrase.. I feel you will see once you go to replace these that there is nowhere for the material to go even if it did deteriorate...not saying it wouldn't perhaps fall out if you removed the cradle, but that's another scenario.
The stock bushings merely keep the cradle somewhat in check on hard turns, that's why it's wishy washy unless you're pulling 1g. (you'll feel the rear sway and "set", that's you getting past the lip and using the actual bushing). The frame is formed into 'sleeves' that the long bolts pass through, and the bolts have washers on the bottom that press against the sleeve. (torqued very high) The circular cradle mounts never actually touch the frame. If they did you'd have alot more rear end and drivetrain noise. At rest and while just puttering along, the only contact is made by a 1/8 inch lip of the existing bushing which isn't even as wide as the pieces of bushing we're calling a bushing.. What I did took out the slop, period. I'm telling you now, unless you're going for all out stiff as hell up your butt jobu handling, filling those voids and adding washers is enough. You could also use a higher durometer material for an even stiffer effect.
I concede that I wouldn't do what I did as an all out 'replacement' for stock bushings even though the material can't just fall out, and under even the most extreme conditions wouldn't deteriorate to the point where it would fall out (not this 3m stuff anyway). I only filled the existing void of the stock bushings with a fairly equal durometer material.
I also am comparing the result of this to the traditional cradle bushing inserts like the GM crap and the much more beneficial spectre bushings.
I hadn't looked until now, but these revshift bushings are completely different than any aftermarket soultion thus far and replace the old bushings instead of being "inserts"...that's going to be a BIG difference. Top to bottom poly AND they connect the frame with the cradle? They are also noticeably stiffer than stock at 80a and 95a. I would say stock is probably 70ish?
Alot of your stock forgiveness in handling is going bye bye as well. This will be like adding a 2" rear sway bar...you will definitely need to relearn the rear's characteristics after installing so you don't do a 180 on your favorite turn to the grocery store..
The stock bushings merely keep the cradle somewhat in check on hard turns, that's why it's wishy washy unless you're pulling 1g. (you'll feel the rear sway and "set", that's you getting past the lip and using the actual bushing). The frame is formed into 'sleeves' that the long bolts pass through, and the bolts have washers on the bottom that press against the sleeve. (torqued very high) The circular cradle mounts never actually touch the frame. If they did you'd have alot more rear end and drivetrain noise. At rest and while just puttering along, the only contact is made by a 1/8 inch lip of the existing bushing which isn't even as wide as the pieces of bushing we're calling a bushing.. What I did took out the slop, period. I'm telling you now, unless you're going for all out stiff as hell up your butt jobu handling, filling those voids and adding washers is enough. You could also use a higher durometer material for an even stiffer effect.
I concede that I wouldn't do what I did as an all out 'replacement' for stock bushings even though the material can't just fall out, and under even the most extreme conditions wouldn't deteriorate to the point where it would fall out (not this 3m stuff anyway). I only filled the existing void of the stock bushings with a fairly equal durometer material.
I also am comparing the result of this to the traditional cradle bushing inserts like the GM crap and the much more beneficial spectre bushings.
I hadn't looked until now, but these revshift bushings are completely different than any aftermarket soultion thus far and replace the old bushings instead of being "inserts"...that's going to be a BIG difference. Top to bottom poly AND they connect the frame with the cradle? They are also noticeably stiffer than stock at 80a and 95a. I would say stock is probably 70ish?
Alot of your stock forgiveness in handling is going bye bye as well. This will be like adding a 2" rear sway bar...you will definitely need to relearn the rear's characteristics after installing so you don't do a 180 on your favorite turn to the grocery store..
12-26-2012, 10:18 PM
#50
tough crowd tonight. I rambled a bit now that I re read it.. The tiny response box on my phone doesn't lend to good editing haha..
The second sentence in the second paragraph is wrong. To clarify, the sleeves are part of the cradle, not the frame. I meant that the circular part of the cradle mount doesn't touch the frame, only where the sleeve meets the frame on the top and at the stock washer/bolt on the bottom.
One tip I remember from twitch on the other forum that helped- lower only one side at a time, makes it much easier to line back up when you're done..
The second sentence in the second paragraph is wrong. To clarify, the sleeves are part of the cradle, not the frame. I meant that the circular part of the cradle mount doesn't touch the frame, only where the sleeve meets the frame on the top and at the stock washer/bolt on the bottom.
One tip I remember from twitch on the other forum that helped- lower only one side at a time, makes it much easier to line back up when you're done..
12-26-2012, 10:24 PM
#51
I hadn't looked until now, but these revshift bushings are completely different than any aftermarket soultion thus far and replace the old bushings instead of being "inserts"...that's going to be a BIG difference. Top to bottom poly AND they connect the frame with the cradle? They are also noticeably stiffer than stock at 80a and 95a. I would say stock is probably 70ish?
Alot of your stock forgiveness in handling is going bye bye as well. This will be like adding a 2" rear sway bar...you will definitely need to relearn the rear's characteristics after installing so you don't do a 180 on your favorite turn to the grocery store..
Alot of your stock forgiveness in handling is going bye bye as well. This will be like adding a 2" rear sway bar...you will definitely need to relearn the rear's characteristics after installing so you don't do a 180 on your favorite turn to the grocery store..
That's not forgiveness, if you ask me. That's slop. I define forgiveness as the tendency for the car to take reduced action (or no action at all) when given an input. Slop, on the other hand, allows the car to do whatever it wants, whether the driver has provided an input or not. The former is okay, if you like that sort of driving experience. The latter is not, no matter how you like your cars.
12-26-2012, 11:30 PM
#52
I agree. The cradle basically floats there, only connected by that bolt. I should have referred to it as 'controlled slop' since it can feel sloppy at times but is never out of control. The car wasn't designed to drag race so the conditions in the video don't accurately suggest there any shortcomings in the design (there are none really).
I elected to simply get rid if that slight slop and retain as much of the stock handling characteristics as possible by extending the stock bushing's dimensions to fill the gap.. The washer I added took up the rest of the slack in the gap and made use of the new "bushing".
I really think another reason they left the front and back of the housing hollow (other than to suppress nvh) was to allow the whole assembly to rock up/down and absorb some of the raw drivetrain torque.
The effect was the most dramatic change I've felt this far in terms of connecting my right foot to the rear end.
I elected to simply get rid if that slight slop and retain as much of the stock handling characteristics as possible by extending the stock bushing's dimensions to fill the gap.. The washer I added took up the rest of the slack in the gap and made use of the new "bushing".
I really think another reason they left the front and back of the housing hollow (other than to suppress nvh) was to allow the whole assembly to rock up/down and absorb some of the raw drivetrain torque.
The effect was the most dramatic change I've felt this far in terms of connecting my right foot to the rear end.
