Cradle bushing replacement... (Page 1/7)
CSM842M4 NOV 05, 05:20 PM
Well, the "new" '86 SE went to get an alignment yesterday. Today the mechanic calls to tell me it's all ready, but that the subframe bushings are done. I think I can do it myself, but the Chilton's says to loosen or remove engine mount and numerous other bolts and remove the lateral links in order to drop the cradle. The mechanic, a fellow Fiero owner, says he just loosened the rear bolts, dropped the front end and pushed the bushings out and in. I'm ordering the poly bushings from TFS, which is a four-corner set. I guess what I'm wondering is, 1. Can I do this in my garage without a gantry to lift the body or a support for the engine? 2. If I drop one end at a time, with the 2.5 engine, is there room to do this? Any experiences/tales of woe with this project, please chime in! Thznks in advance - Chris
CSM842M4 NOV 05, 05:55 PM
Quick update - just drove back from the mechanic. Wow. Car wiggles around randomly at city street speeds, gets pretty squirrely on the highway. Seems to happen most when adding throttle. Do this sound like cradle bushings?
Blacktree NOV 05, 06:12 PM
Could be a lot of things. But the mechanic should have noticed if something else was wrong. You have to jack up the rear of the car to replace the cradle bushings. While you're doing that, you can check if anything else is loose in the suspension.

The cradle bushing swap can be done at home, with a pair of jackstands and a floor jack. Put the rear end on the jackstands, and use the floor jack to lower and raise the cradle. The back of the cradle should hinge down with no issue. But to lower the front of the cradle, you'll need to loosen the rear cradle bolts a little bit, to make some slack. Just be mindful of any hoses and cables that might get stretched or pinched in the process.

That said, those bushings can be stubborn. You may be in for a fight. Laying under the car will make it more of a hassle.

[This message has been edited by Blacktree (edited 11-05-2020).]

CSM842M4 NOV 05, 06:20 PM
Thanks, Blacktree. Mechanic said one of his fronts practically fell out, the other not so much. He also said a ball joint/control arm bushing press should do the trick. So I'll turn my air pressure regulator up to 11 and let 'er rip!...
Blacktree NOV 05, 06:33 PM
The engine cradle is part of the rear suspension. When the cradle moves around, it brings the control arms along for the ride. So yeah, it can really mess with handling.

There is no beneficial effect from cradle movement. Any movement of the engine cradle is bad. That's why I always suggest solid cradle bushings. But urethane is the next best thing. It'll still be an improvement.

[This message has been edited by Blacktree (edited 11-05-2020).]

Dennis LaGrua NOV 05, 07:53 PM

quote
Originally posted by Blacktree:

The engine cradle is part of the rear suspension. When the cradle moves around, it brings the control arms along for the ride. So yeah, it can really mess with handling.

There is no beneficial effect from cradle movement. Any movement of the engine cradle is bad. That's why I always suggest solid cradle bushings. But urethane is the next best thing. It'll still be an improvement.




I've been using poly cradle bushings with success. Big improvement but I would not suggest trying to replace those bushings while the cradle is still in the car. You can use an engine support bar to hold the powertrain in place without disconnecting a lot. On the four its not that hard to remove just the cradle. The exhaust needs to be removed, along with the tie rods and the lower pinch bolts for the rear knuckle. Then you disconnect the mounts, remove the cradle bolts and the cradle should drop down.

------------------
" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

theogre NOV 06, 12:06 PM
Cradle rubber may be bad... Iffy rear can also be crap engine/trans mounts and dogbone problems. More so w/ stick trans cars. They should be check/fix on top of cradle problems.

Replace cradle set is "easy" enough and don't need to pull the cradle....
But
Front Cradle and other bushings w/ metal outer shells often have rotten outer shells. Worse can be hard or impossible to see w/o playing w/ mirrors, picks, etc. Even then very hard to find damage where rotted inside whatever part.

Any part of Outer shell gone mean little or no compression to the rubber.
Is also a big problem trying to Install polly and some metal replacements because need a good outer shell saved from old rubber.

Removing rubber in front cradle... See my Cave, Bushings and likely Bump Steer and rest of section.

Cradle won't move to make "polly noise" problem but still needs some Sil Grease just to keep out water between shell/sleeve and polly. Polly won't compress to fit 100% of outer shell leaving voids to hold "water" and rot inside out.

Cradle bushings can be done in the car often w/o screwing up alignment.
First make sure all bolts can be removed. Rear bolt's "Captive Nuts" are every well known problems.
Do Front bushings First then rear.
Rubber have enough play to allow you to replace fronts 1 at a time then both rears w/ polly. Polly is more flexible but final tighten front bolts after installing all of them.
Metal fronts often need both front bolts loose or out to install them. leave front bolts loose to install rear w/ metal parts.

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

Dennis LaGrua NOV 06, 12:37 PM

quote
Originally posted by theogre:

Cradle rubber may be bad... Iffy rear can also be crap engine/trans mounts and dogbone problems. More so w/ stick trans cars. They should be check/fix on top of cradle problems.

Replace cradle set is "easy" enough and don't need to pull the cradle....
But
Front Cradle and other bushings w/ metal outer shells often have rotten outer shells. Worse can be hard or impossible to see w/o playing w/ mirrors, picks, etc. Even then very hard to find damage where rotted inside whatever part.

Any part of Outer shell gone mean little or no compression to the rubber.
Is also a big problem trying to Install polly and some metal replacements because need a good outer shell saved from old rubber.

Removing rubber in front cradle... See my Cave, Bushings and likely Bump Steer and rest of section.

Cradle won't move to make "polly noise" problem but still needs some Sil Grease just to keep out water between shell/sleeve and polly. Polly won't compress to fit 100% of outer shell leaving voids to hold "water" and rot inside out.

Cradle bushings can be done in the car often w/o screwing up alignment.
First make sure all bolts can be removed. Rear bolt's "Captive Nuts" are every well known problems.
Do Front bushings First then rear.
Rubber have enough play to allow you to replace fronts 1 at a time then both rears w/ polly. Polly is more flexible but final tighten front bolts after installing all of them.
Metal fronts often need both front bolts loose or out to install them. leave front bolts loose to install rear w/ metal parts.




I sincerely doubt that you can easily remove the front cradle bushings while it stays attached to the car. You may be able to do it by dropping it down slightly but then what. We've always used heat to melt out the old rubber and reuse the sleeves for poly but they usually catch fire.

------------------
" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

theogre NOV 06, 08:49 PM

quote
Originally posted by Dennis LaGrua:
I sincerely doubt that you can easily remove the front cradle bushings while it stays attached to the car. You may be able to do it by dropping it down slightly but then what. We've always used heat to melt out the old rubber and reuse the sleeves for poly but they usually catch fire.

Only Fools burn the bushing out causing many Dangerous even Fatal Problems. If you prevent that, Burning the bushing also heats the shell and "frame" you want to save causing heavy heat cycling, removing any rust protection and often heat treating making them weak. Burn metal rust big time and fast and can't repaint front shell easy to stop this.

I can and have done them in the car following directions in my cave by only heating the middle sleeve to push or pull it out. Again, Bushings near bottom in "Shell Games." Rubber will not transfer core heating to the shell enough to matter.
Very easy w/ Pencil Tip propane torch blowing heat thru the sleeve like BernzOmatic UL2317 (just this often sells < $15) and similar. You don't need max heat output from the torch but many need heat guards/shields made of soup cans protecting brake lines etc. (Heating brake line above 212°F(100°C) can boil old wet fluid then need to bleed rear brakes.)
Many have bigger tips or have torch w/o fuel control only 100% on or off and doesn't work well for this job like BernzOmatic JT680 TS4000 or TS8000.

If a rubber sleeve/core is frozen to the bolt, directions to remove without cutting or heating are there too. But many id10t will post to do either or both to the bolt that wreck the frame and destroys hard to get Class 10.5 or harder bolts. Heating the frame or bolts to glow will screws up heat treating and make them weak. Most get sloppy cutting and cut the frame making stress risers at minimum.
If you open the sleeve and still stuck use PB Blaster etc in the opening let it work. You'll get a lot more "oil" actively working when open the sleeve first.
Picture shown there is stuck sleeve removed then pulled out by following above.
wftb NOV 06, 11:00 PM
To get the rubber out I just use a drill with a 1/4" bit in it.Drill in between the shell and the rubber and it will just "walk" around the rubber and separate it from the shell. Clean it up with a rotary wire brush. Poly is a total waste of time get solid mounts. The 88's have solid mounts for a reason, you do not want any movement between the cradle and frame. I have a set of poly mounts I will give them to you for the price of the postage. And that is more than they are worth.

------------------
86 GT built 2.2 ecotec turbo
rear SLA suspension
QA1 coilovers on tube arms