Front/Rear Subframe Bushings/Isolators

[wufibug]

This has been a topic of great concern on this forum for more than 15 years.  Having come face to face with this task, I read most of the previous posts.  While they are helpful, they are also a bit confusing and seriously mind-boggling.  Confusing because the posts sometimes don't distinguish between the front and rear, which are quite different, and mind-boggling because because unless the car is rarely or never exposed to water and salt, these parts deteriorate surprisingly quickly for a fundamental part of the frame.  Deterioration has marked effects on ride and handling, and can lead to really serious consequences.  My car spent a few years in Ohio and there is some surface rust on the undercarriage.  The bushings or isolators on the other hand, had almost completely disintegrated making removal the nightmare described in earlier threads. I have only pulled the 2 beneath the driver's seat, but so far there is not one part I would consider reinstalling.

What shocked me is that the unit is not, and has never sold as a kit or assembly.  From what I can tell, the whole business, rubber and metal, deteriorates pretty much in unison and then begins taking the surrounding frame down with it. They are not very accessible, and when things start to crumble, you're going to have to find a real pro to deal with it and a mortgage broker to help pay for it.  To say there is no market for such a kit is only to affirm that few of us ever take a good look at a component that should be inspected at every brake pad interval.  What is further upsetting is that most of the components seem no longer to be available or at least very difficult to pin down.  Some of the early posts had very detailed lists that included part numbers. Unfortunately most of those numbers do not produce an internet hit of any kind.  Probably far easier to find these particular suspension parts for a Model A or Edsel than for our Reattas.  Why is it so easy to find multiple suppliers of an inner tie rod, an item that does not, as far as I know, fail with the frequency of these bushings? 

So what's the point?  Does anyone have a list of part numbers that result in actually being able to obtain all the items that make up these bushings?  One possible reason these components are extinct is that unlike inner tie rods, these bushings are pretty much unique to Reattas.   I recall, however, that Daniel, coming to the rescue as he has so often over so many years, wrote that Fiero bushings would fit, possibly with some minor alterations.  But what year car and which components of these bushings can we migrate over to our Reattas?  

In the decades since this was a major issue, has someone discovered a source for parts or a vehicle whose parts can be readily adapted?

Oh, and if you haven't given these bushings a close look, now would be a good time.  They go from "not too bad" to "just try and get me out" in record time.

[2seater]

This is the best guide I have found and have used it to do two different Reattas. The Dorman mounts and the GM bolts are still available to the best of my knowledge. The Dorman mount has a larger contact area and seems to firm up the front end, although that could just be the new vs old effect? I have never changed the front two bushings which are not subjected to the same spray and splash as the rear four, and seem to work as locators rather than actual supports. Of course this is only my opinion so take that for what its worth🙃

 

https://reattaowner.com/roj/guides/210-suspension-a-brakes/77-suspension/328-engine-cradle-sub-frame-bushing-replacement

[wufibug]

This is marvelous news as I had long ago bought the Dorman mounts thinking they were the same as the OEM.  I was much chagrined to see  that they were not the same at all and was ready to sell them off.

Looks to me like the Dorman mount was designed to have the center bolt go in top to bottom so it centers itself properly.  Because we don't enough room to insert it from the top down it has to be inserted bottom to top.  This allows it to move side to side in the oval space of the top mount.  Seems like some kind of spacer or filler in that oval recess in the top section would help stabilize the center bolt.  Since my washers were mere shadows of their former selves, I would have to source a new washer to go under the top nut.  Does that washer remain between the mount and the body of the car or is it just used to compress the two sections of the mount?

 

Edited May 2 by wufibug
Clarify (see edit history)

[Dashmaster]

That write up is was done by me. The D shape of the Dorman Bushing will not move, It fits tightly into the cradle mounts. See the part that talks about seating the bushing.

[2seater]

I do remember that tightening the bolts is a long and tedious process gradually compressing everything and reaching the torque settings. Especially if doing on your back on a creeper🤔
 

I see the author has responded and he knows exactly what to do. I deleted my current comment😊

Edited May 2 by 2seater (see edit history)

[wufibug]

I will try to make this my last question . . . on this topic.  Does the washer at the top that is used to help compress the two halves of the mount remain between the body and the mount or is it discarded?

[wufibug]

PS:  You guys have no idea how much I appreciate you help on this.  The impact wrench helps with the tedium; nothing helps with having to deal with the forces of nature that make for rust and corrosion while lying on the pavement under a car.

[Ronnie]

1 hour ago, wufibug said:

The impact wrench helps with the tedium

I've not replaced cradle mounts so I may not know what I'm talking about, but I don't think I would use an impact wrench to remove the cradle mount bolts. As I understand it, the bolt goes into a caged nut. If that is the case, it seems to me an impact wrench would be more likely to break the caged nut loose inside the cradle than using a breaker bar to work the bolt back and forth as you take it out to prevent the bolt from seizing as it is removed. If you break the caged nut loose I think you have to cut a hole in the cradle (or maybe the body?) to replace it.

[wufibug]

Ronnie, I think the problem many of us have is that we simply didn't realize to extent to which nature had its way with these components.  In my case little force was required to remove the center bolt because if not the bolt itself, everything around it was eggshell thin and held together only by rust.  The 3 little nuts that held the OEM mount in are 10mm and often about the only thing with a modicum of integrity. The location, however, prohibits the use of a ratchet/socket, and most 10mm wrenches don't afford you much leverage. I was able to use a ratcheting 10mm box wrench to make that go a bit faster.  I also had the advantage of doing a nearly complete suspension rebuild, so tie rods, lower control arm, strut, caliper, brake backing plate and steering knuckle were off the car to be cleaned up and painted [it's now a California car so that stuff should look OK for a couple of years.

I've got a product called "Krud Kutter" that makes number of extravagant claims about removing and inhibiting rust.  Never used it and relied on internet reviews.  I'm going to wire brush what I can and then spray the bottom of the body and undercarriage with this stuff.  I have mixed feelings about following with  some undercoating over that.  Some say that undercoating merely traps moisture and therefore does more harm than good.  I'd appreciate feedback on that.

[2seater]

You can use any good nut, bolt and washer setup to squeeze everything into place initially but all of those parts, including the top washer are removed before the subframe is re-married to the body.

[wufibug]

Just kill me and get it over with.  The bolt for the isolator in the #2 position unscrewed. The rest just fell apart.  The bolt for the isolator next to it broke.  The rest fell apart.  Then the encased nut in the little compartment detached so gripping the bolt no longer had any effect. No way to grip the nut. Thought if I cut the bolt right next to the body it would be short enough so I could pull it up and out through the "window".  Yeah, sure.  Have now drilled to holes through the nut and it still won't release the bolt, which is so hard it dulled my metal Sawzall blade without marring the threads. I am now on day 3 with this one bolt/nut.  I will take a dremel tool and metal cutting disk and see if I can cut enough of the nut to release the bolt.  I have been soaking the other 4 isolator bolts/nuts with PB Blaster for a few days though this did not really make things easier on the first two. I don't even want to think about what awaits me on the other 4.

I've long ago run out of expletives for GM and whoever designed the OEM subframe mounts.  This is the most agonizing and frustrating automotive job I've ever tackled, and I have 3 Jaguars.

[wufibug]

Now that victory is mine, I finally see how the #2 and 3 isolators were actually designed.  The design makes it clear that GM never contemplated these cars being driven under harsh road conditions that would mate bolt and nut till death and beyond.  The bolt that goes through the isolator and holds everything together screws into a nut that is welded or cast onto a diamond shaped plate. The nut/plate is free floating, sandwiched between the frame and another top plate.  As the bolt is turned, the nut/plate hits the side of the frame to enable tightening.  When the bolt rusts solid to the nut/plate and breaks off, the sandwich design pretty much negates the effect of sprays or heat. To get the bolt and its plate out, the top plate has to be pried off and pulled out, normally in pieces.  Even cutting the broken bolt off at the bottom of the frame will not allow the plate/nut and bolt stub to come out.  After drilling 3 holes in the nut I was able to break the top off and pull it out.  I then ground off the nut and removed the bolt stub.  I will reuse the diamond shaped plate by bonding it to floor of the frame to add strength.  Since the old nut is history, I can use the M14 bolt that comes with the Dorman replacement isolator and a new nut. Probably add a fender washer and lock washer. 

Isolator #3 is similarly encased in the frame.  However it is in front of the wheel so gets less direct tire spray, and it has a plastic cover so it is not bathed in road salt. It came apart quite nicely and probably could have been reused.