Should I or shouldn't I, to bush or not Options

[iankarr]

Hi Guys,

I've disassembled the rear of the bumblebee and the control arm pivots and bushings look to be in good shape.

My plan was to blast and powdercoat the control arms, which would require removing the pivots/bushings (due to the heat)...but I hear re-installing these can be a beeotch. And I generally prefer keeping as much OEM as possible.

So...do you think it's worth leaving the bushings and pivots alone and just painitng the arms? I'm aiming for this bumblebee to be a solid #2 car when done.

Thoughts? Thanks!

[76-914]

Too bad we're 2000 miles apart. We could do a video that would simplify this process for others. (IMG:style_emoticons/default/beerchug.gif)

[iankarr]

Too bad we're 2000 miles apart. We could do a video that would simplify this process for others. (IMG:style_emoticons/default/beerchug.gif)

I think you just tipped the scales, Kent. Part of why I got this BB was to do videos documenting every step of restoration. Thanks for reminding me why I shouldn't skip this. I'm happy to take your reccos, though!

I remember @eric_shea talking about how the bushings need to be jb welded in to the arm. Any other tips?

@Superhawk996 you make valid points. Do you think that the modern replacements are inferior...or just different?

Thanks, everyone for chiming in. And Jeffrrey
@914_7T3 ...wow!

[Superhawk996]

Do you think that the modern replacements are inferior...or just different?

I'll start with the fact that I'm biased toward OEM both because I work in the industry and because I used to be involved in chassis tuning. I know how much work goes into engineering bushings and it's not as simple as most think it would be.

Short answer. Because they will be different.

Long answer. Porsche engineers knew what they were doing when it engineered the bushings as vulcanized parts. What might seem like minor differences in bushing design (press fit vs. canned vs. vulcanized to inner/outer cans) can make a huge difference in ride, handling, and NVH.

I'd be a whole lot more inclinded to replace the bushings had they been designed to be replaced. If they were a canned bushing that could simply be pressed in/out of the trailing arm, I think I'd certainly do it. But . . . that is not what they are.

I think there are lots of good reasons to replace a set of obviously worn and/or damaged trailing arm bushings, but, personally, I'd never do it just for the sake of doing it. Though rubber does age, it's a matter of degree and in this case, most of the rubber is vulcanized within the trailing arm and isn't exposed and won't age out as fast as a fully exposed bushing. Yes, the rate will definately be different than it was in 1973 (my car's age). Without data on the installed rate of the OEM bushings vs. new aftermarket bushings of a different design, we are all guessing.

To be completely transparent, it's a hard question to answer the question without data acquisition and some objective evaluation metrics to compare against.

You'd be surprised how evaluation bias (knowing a set of bushings has changed) can over ride subjective comparisons. There have been times when I drove cars blind (not knowing what was changed) and I thought I knew what was changed, made a subjective assessment, only then to find that the objective data didn't match the subjective assessment, and that the parts which were changed were not those that I thought. I.e. I was completely wrong!

Driving parts blind is something that good development engineers do from time to time to keep evaluation skills sharpened and to keep themselves honest. Most of us working in garages on our hobby cars can't do this (we know what was changed) and are inclined to think that we've improved things even if we haven't. Sometimes the metrics change (like wanting improved handling vs. OEM ride or OEM NVH) and that justifies the improvment. Other times, it's just wishful thinking. Been there done that.