Clunking and AL SFBs

[TimboSHO]

About a year and a half ago, I installed aluminum sub frame bushings on the rear of my subframe (the front ones were still good, so i left them alone). Just a month or so ago, the subframe started clunking. I went underneath for a look-see, and the rear bolts were loose! I put some locktite on and tightened them up, and it's been fine until a couple of days ago. Now it's clunking again. Everything is tight (I even pulled the carpet up and checked to make sure the nuts were tight and in place).
I'm not sure if anyone else has had this, but I'm wondering if it might be my subframe rusting through, and the added stress the AL SFBs put on it is acually hurting my subframe. My car is very rusty (hole in the driver's floor, holes in the body all over, even a-pillars about rusted through--talk about wind noise on the highway ), and I'm wondering if anyone else in the rust belt has experienced this as well.

BTW: I just installed new motor mounts about the same time I did the SFBs, so it's not them making noise. It's definately from the rear of my subframe, as I can feel it under my feet when it clunks.

Thanks in advance for any information or ideas.

 

[TYSHO]

When do the clunks occur?

 

[TimboSHO]

The clunking occurs when I accelerate, brake, and change direction. But, for instance, if I turn left and it clunks, if I make another left, it doesn't do it again. It's like something moves, like it shifts. But I had it up in the air and I pryed on everything and couldn't get anything to budge.

 

[TYSHO]

Look in to this: http://www.shoforum.com/showthread.php?t=56503&page=1

 

[TimboSHO]

Thank you! I'll look at those as soon as I can get it in the air again (monday)! Sounds pretty easy to weld those up!

 

[Rockledge]

Have you taken down the subframe and looked things over carefully?

I'm no suspension guru, but FWIW:

I previously did something similar to you, kinda as a trial run. What I did was, after I installed ALSBs (4) and drove around like that for a while, I decided that they were just a little too harsh for my liking. So I had an idea to try out some Gen. III bushings only on the rear of the subframe while keeping the ALSBs on the front (I felt this would provide the most direct insulation between driver and engine in that regard). This "hybrid" combination of bushings improved HVH as I hoped, but in all honesty I eventually came to the opinion that the car was handling "funky" for some reason. It's hard for me to describe exactly, but I often got the sense that my SHO wasn't being entirely "true" whenever I was putting it through its paces in the corners. Words like "wiggle" and "twist" come to mind, but again, I'm not sure if I woud use those precise terms. This was before I had installed new Tokicos and Eibachs and other upgrades, so it was essentially a 10 year-old stock suspension otherwise.

In short, I didn't care for the "hybrid" SFB arrangement, and so it would not come as a surprise to me to learn that mixing SFBs can cause undue and unexpected stress(es) at the areas where the subframe mounts to the body.

I now have the Gen. III bushings all around and I no longer have that same uneasy feeling that I had before with the mixed bag of SFBs. I do believe that the consistency of subframe bushings probably has a lot to do with that, although I've pretty much upgraded the entire suspension since then, so it's hard for me to compare apples directly to apples.

P.S. There has been a few recent threads about front clunking noises caused by problems with the subframe where the tension strut rod connects up. Apparantly the inserts that are on the subframe (some refer to them as "seats") can seperate due to rust and/or corrosion. If you look back a few pages in the suspension forums you'll find the threads (- looks like TYSHO's on top of it already )

 

[TimboSHO]

Thanks man. Yeah, I was thinking about putting some stock ones back there just to see if that clears it up. I'll check the strut rod recievers first though.

 

[TimboSHO]

Alright, I found the cause. The strut rod recievers were fine (I welded around the edge just for PM). The right rear subframe hole was a little bit elongated. I took the mount out (it was pretty corroded together, so it took a little bit), found the hole to be elongated, and thought of a fix. It's kindof hard to explain what i did without a picture, but i'll try. The subframe was being allowed to move around a little bit because the two parts of the bushing were not coming together. So I cut about .25" off the one that fits inside in order to allow the other one to clamp tight on the subframe when the bolt is tightened down. I put some silicone around the edges, just in case it did start moving again, it might not clunk as bad.

I guess that's what I get for installing AL SFBs on a michigan car. But an elongated hole is better than a broken subframe I suppose!

 

[SHObill]

Tim, you must have a set of the those 'superior Design' SFB's =cup style. Thou they do provide support under the nut, But they are also designed to take into account the SF material thickness but do not take into consideration the 100K+
10-15 year old 'wear&tear' of the SF steel.You were not clamping the subframe anymore & did the right fix by removing material off the lower bushing top surface which plugs ioto the top half. Uninstalled the two surfaces that clamp the SF should touch so it will always clamp. People, on a daily driver that has at least 100K & EVERYTHING has not been replaced SOLID ANYTHING is NOT GOOD! It will lead to pre-mature failure of somthing else down the line.

 

[ant-live]

I just recently had the same problem after installing the cup style...but my problem was the bushing bracket broke in two...i had to order a new one from Lincoln(Ford) and installed it last night...it is a lot stronger and has a differ design than the one that broke.

 

[BlackandBlue]

I just recently had the same problem after installing the cup style...but my problem was the bushing bracket broke in two...i had to order a new one from Lincoln(Ford) and installed it last night...it is a lot stronger and has a differ design than the one that broke.

Confused by what you mean by bushing bracket? Pic?

 

[ant-live]

Sorry, i don't have any pics..but the bracket that holds the sway bar and sway bar bushing to the frame right above the subframe bushing(in the front).

 

[BlackandBlue]

got it.