Differences between VBP and energy Suspension poly UCA bushings: flange vs no flange
 

I have two options for poly upper A-arm bushings; 1) some old-but-never-used bushings that came with the car, which I think are probably VBP brand; and 2) Energy Suspension bushings that I bought because I didn't realize I had those VBP bushings on the shelf (d'oh!). The two-piece bushings that go in the rear UCA pivots are similar enough. But the one-piece bushings that go in the front pivots are different. In the picture below, you see the EG bushing on top and the VBP bushing below. The EG bushing has an inner flange, which makes installing it a real bitch (plenty of threads on this forum will attest to that!). They look identical to the Prothane bushings in this regard. The VBP has no inner flange at all: it just presses in and is held in place by the washers and the nut. VBP is no longer in business, but they certainly were known for Corvette expertise. I also think the Van Steel bushings look like the VBP pieces, fwiw. So the question is: which one should I use? Is there really some good reason to use the EG one and deal with pressing it in and also having it be a bitch to remove if I ever need to take it out? Why is that damn flange even there? If it isn't needed, what's the harm in cutting it off? If nobody has any strong tech that says the EG bushing is really better, then I'm just using the VBP bushings. What do you all think?

https://cimg5.ibsrv.net/gimg/www.cor...a594ec9f9b.jpg
Two options for the smaller-diameter, one-piece UCA bushings. The Energy Suspension version is top, and the VBP version is on the bottom.

Don't know but looks like the bottom one is missing something. Is there supposed to be a washer or something on the left side of the bottom one?

Is it to positively locate the arm?

Under track conditions, can the arm shift if you remove the flange?

There will be washers on either side of all UCA bushings. I just didn't include them in the picture.


I would assume that's the purpose of the missing flange. However, the rear bushing assembly has flanges on both sides, so it will positively locate the arm. The bushings on these arms shouldn't see much in the way of forces that try to pull them backwards along the bushing axis. They're going to see tension and compression loads from cornering, and the front bushing will see mainly tension from braking force. Also, the small flange on the EG bushing does provide some resistance to the arm moving backward (which is why it's so hard to press in), but if we can press it in then it seems like cornering and braking forces could press it back out if they were in that direction. IOW, I wouldn't want to be my car's structural integrity on that little flange! And VBP and Van Steel don't seem to think it's a problem. So I'm still scratching my head.

My guess would be that the energy suspension one may be used in multiple applications with similar dimensions and the VBP is Corvette specific. In a different application that flange may be used, but not necessary on the C4.

I have the energy suspension on mine. VBP was about 45 min to an hour away, when they were still open. I went to their shop and bought new springs and a few other things from them, but it seem like their technology stopped in the 90's. They sold quality products but in my opinion they seemed to had troubles with the poly and rubber suppliers.

Sounds like I should use the VBP bushings and keep the EG bushings as spares, just in case.

Last night i happened to look at my upper a-arms on my 88. It has full VBP poly bushings.....The one with 2 lips was in the forward position, and the one with only 1 lip was in the rear location...

I can put a pic on here if needed.

I also still have the original instructions from VBP. I can scan if you need.

That's...really strange. The bushings clearly go in the opposite positions, and they are different outer diameters so they can't possibly be installed in the wrong holes. That said, I actually wonder if your arms are on wrong sides of the car, like you have the left arm on the right and the right arm on the left side. If you post a pic, we can figure that out.

I would be happy to have those, just for completeness' sake. I have the ones for the offset lower control arm bushings, but for the uppers.

I did my suspension over 12 or so years ago. Pretty sure everything is right (left and right sides), but would be funny if it wasnt!!!
I only glanced at mine last night, and this post was in my head, thats what made me chime in.....On my post entitled "Just for the hell of it" in the general discussion, there are pics, but dont think you can see the arms very well, so ill get pics tonite, but prob wont be able to post until tomorrow. Ill also scan those instructions and post them as well...

In that topic you started, I found the following pic:
https://cimg7.ibsrv.net/gimg/www.cor...eb607f1bd0.jpg

Based on that, the arms appear to be on the correct sides, and I see lips/flanges on both ends of the rear bushings. To be clear, the rear of the arm in this pic is on our left, and the front is on our right and slightly cut off in the photo. The rear bushings are the two-piece units: each bushing half has a flange, and they go in each end of the bushing hole to essentially form one bushing with a flange on each end. It's hard to tell about the front bushing: it either has no flange or a smaller flange like my EG bushing. Also, does it have a washer there? I don't see one, but it may just be obscured in the photo.

PS - As another data point for those of us interested in this topic, it occurred to be that the Global West Del A Lum bushings for a C4 also have only one flange. In fact, that is the case for both front and rear UCA bushings from them! They are also using flat steel washers in place of the factory washers, like I am. See below:
https://cimg5.ibsrv.net/gimg/www.cor...0e20572c47.jpg
https://cimg7.ibsrv.net/gimg/www.cor...40267d8f7a.jpg

PPS - Ignore the red arrows in the picture above!

Yeah i was gonna post that pic, but figured id get better pics tonite.
So ill get some up close ones later today.

https://cimg3.ibsrv.net/gimg/www.cor...7428420467.jpg
Driver side rear
https://cimg5.ibsrv.net/gimg/www.cor...151e16418b.jpg
Driver side front

https://cimg3.ibsrv.net/gimg/www.cor...bb29950f4e.jpg
Passenger side a little easier to see
https://cimg4.ibsrv.net/gimg/www.cor...8fe98deada.jpg
Passenger side rear
https://cimg6.ibsrv.net/gimg/www.cor...cfe73ebc9a.jpg
Passenger side front

I also have the VBP instructions for all the other poly bushings and springs as well if anyone wants them posted.

Thanks for posting all of that. It looks like your car is what I was expecting: the two-piece bushings with a flange on each end of the A-arm hole are on the rear, and the one-piece bushing with only one flange is up front. I appreciate the directions: no surprises, but nice to have them for documentation.

No problem. Enjoy!