C3 and VBP Smart-Struts and Rack Attack

[Tony Roussos]

Greetings everyone. It's been a while since I've visited.

Regarding a 1971 SB Coupe, what are your thoughts about using the VBP Smart Struts vs original style struts? I like the thought of heavier duty tubing, forged ends, and eliminating the adjustment cam that can slip out of adjustment.

Also, interested in your thoughts on the Rack Attack rack and pinion upgrade from VBP?

I'm more interested in a reliable driver instead of a show car.

Thank you for your response.

Tony

[Joe L.]

Re: C3 and VBP Smart-Struts and Rack Attack

Tony-----

In 200,000 miles of driving my 1969, I've never had any real problem with the rear struts. I've never had a case where the camber adjustment cam "slipped" out of adjustment.

The main problem with the factory struts is wear of the end bushings. These are easily and inexpensively replaced and it's not necessary very often. To get improved durability for the strut rod bushings, convert to the 75-79 style strut rods with larger bushings. These are also the part which GM catalogs as SERVICE for 63-74 Corvettes. I don't think you'll drive the car long enough in your lifetime to wear these out.

[Tony Roussos]

Re: C3 and VBP Smart-Struts and Rack Attack

Thanks for the response, Joe.

For starters, since I've owned the car, the struts are both bent. Presumably during an alignment as a corrective action to meet specs instead of tackling the real problem. Not really a problem of the struts I imagine. Most likely a hack alignment shop?

Secondly, VBP claims less alignment deviation during wheel travel over stock, thus keeping more tire on the road and less tire wear?

Thoughts in that regard?

Thank you.
Tony

[Joe L.]

Re: C3 and VBP Smart-Struts and Rack Attack

Tony-----

The bent struts are virtually always the result of bogus rear wheel alignment methodologies. As you surmise, it's an easier and less expensive means of correcting the underlying problem which is worn bushings. This was once so widely practiced, even by Chevrolet dealers, you would think that it was the procedure outlined in the factory service manual. It wasn't though. In any event, there is virtually no way that the struts will bend for other in-service reasons.

Vette Brakes is probably correct. However, what you gain is not really all that meaningful for a street driven car, even one driven "at the limits" of sanity. The benefit produced by the aftermarket struts might be useful in a racing condition, off-road. What you will likely lose with the Vette Brake struts is ride smoothness. In other words, the solid configuration strut rod ends will be less compliant and will generate ride harshness. It's a poor trade-off for a street car: you gain nothing of importance and you lose something of importance to "gain" it.

[Tony Roussos]

Re: C3 and VBP Smart-Struts and Rack Attack

Joe,

Thank you for the explanation. I like to think I drive sanely? Do you recommend Polyurethane strut bushings or rubber?

Thank you.
Tony

[Joe L.]

Re: C3 and VBP Smart-Struts and Rack Attack

Tony-----

Stock rubber. Always. Polyurethane bushings are less compliant. Plus, they invariably generate noises and squeaks. You get enough of those already in many Corvettes. The larger diameter 75-79 strut rod bushings will last as long as you need them to and perform as well as you need them to.

[Jim T.]

Re: C3 and VBP Smart-Struts and Rack Attack

Tony I have the Vette-Brakes strut replacements on my 70 and like them, I really find no additional harshness although I also installed the composite rear spring from Vette-Brakes at the same time. Don't miss the Corvette squat when I go pedal to the floor. My alignment person likes these struts as well, easier to get the alignment right on accordiing to him.

[Jim T.]

Re: C3 and VBP Smart-Struts and Rack Attack

Forgot to mention this. Less than one month after taking delivery on my new 70 Corvette the turbo 400 stopped suddenly shifting into second and third. Drove it to the dealership and they took it into the work area. Walked outside later and saw my new 70 Corvette that had been lifted with prongs of the lift on the front frame sections, however on the rear they were lift prongs were using the rear stuts to lift the car. Went directly to the manager of the dealership without talking to anyone else and had him come and look at what they had done. It bent the stuts which you could see when they let it down. I had to go to a different location to their insurance company and file a claim to get my bent struts replaced. Another reason I don't like others working on my cars. The transmission problem was easily fixed, the rubber vacuum line connection at the vacuum modulator had disconnected.

[Tony Roussos]

Re: C3 and VBP Smart-Struts and Rack Attack

Thanks, Jim.

That's why I usually prefer to perform my own repairs. It's pretty bad when the dealership that sold the car screws-up. (I'm sure most of the dealerships are quite competent.) I just don't like taking that kind of chance.

What I'm after is upgrading if the performance benefit outweighs stock without side-effects.

I kind of like the Corvette "squat" but I can do without squeaks and groans.

I'm thinking composite spring for durability and longevity.
Smart struts would satisfy durability, ease of alignment, and improved performance (Keeping more tire on the road.) As Joe points out, for normal driving conditions, the benefits published may not apply.

Decisions, decisions, decisions!

Tony

[Peter B.]

Re: C3 and VBP Smart-Struts and Rack Attack

Well, Over the years, I trusted Joe's recommendations very well. He has never steered me wrong (pardon the pun). The way I look at it, Chevy's Corvette team was always a GREAT design team and I trust the design they put together on the car. I feel that many (maybe not all) of the aftermarket changes to improve performance is good for the track but not for riding every day. BTW, I have a 1971Convertible and my only problem is I want to drive it all the time which stops me from making restoration projects on it. Good Luck

[Tony Roussos]

Re: C3 and VBP Smart-Struts and Rack Attack

Peter,

I agree the C-3 Corvette design team was tops, but if they had today's material, would they still opt for rubber and steel springs? If they had their choice, what would they do? I wonder where they are now (besides Zora) so we can ask them directly!

Tony

PS I just paid off the loan and am planning the budget for repairs/restoration. Then I'll drive it all the time.

[Tony Roussos]

Re: C3 and VBP Smart-Struts and Rack Attack

Does anyone have thoughts about installing a Rack n Pinion upgrade?

Thank you.
Tony

[Michael W.]

Re: C3 and VBP Smart-Struts and Rack Attack

You might want to ask over at the Corvette Forum website, much more oriented to modifications.

[Joe L.]

Re: C3 and VBP Smart-Struts and Rack Attack

Tony------

As far as I know, the same sort of rubber suspension bushings are used in most cars manufactured today. I don't think that urethane bushings are generally, if ever, used in modern PRODUCTION applications. That's one of the reasons that I steer clear of them-----if they are so great and, obviously, available, why aren't they used in modern-day cars?

All metal type connections (like the Vette Brakes parts you mention) are used in some PRODUCTION applications, but not too many.

[Tony Roussos]

Re: C3 and VBP Smart-Struts and Rack Attack

Joe,

Very good arguement. The one reason I can think why urethane is not used would be expense. If urethane is cheaper and modern cars still use rubber, then we have a good idea what the "founding" engineering team would have chosen.

I guess I'm walking a fine line. I very much want to restore and maintain originality, but as a driver I'd like benefits of modern technology. It seems like a question of when or when not compromise on original materials and technology.

Your input is valuable, Joe. Thank you for maintaining focus.

Tony