I see a flaw with the stiffeners

The BT Tech Prius Stiffening plates are made from billet 6061-T6 and are type 3 hard anodized and bolts to the frame using stainless steel M8 bolts that are recessed in our plate. As you know hard coating anodizing is an EXTREMELY strong scratch resistant method of protecting aluminum. The Rockwell hardness of our hard anodized finish is between 62-70 vs. less than 30 for a powder coated finish.

Using mild steel with powder coating is NOT a material I would chose to work with. Powder coating could rub off leaving the mild steel unprotected and will start to rust immediately. In addition to the poor corrosion resistance, mild steel is approximately 3 times heavier than 6061-T6.

Anodizing is critical to the aerospace industry. The aerospace industry and the military use mainly hard coat anodizing because it renders the aluminum extremely hard (60-70 Rockwell C), heat resistant, provides corrosion resistance of 336+ hours per ASTM B117, and it provides electrical insulation of 800v/mil thickness. Hard anodizing also yields a product resistant to harsh weather, salt sprays and abrasive machining processes.

Aluminum processed by hard anodizing can be only a few points away from the hardness of diamonds.


Thanks!!

Brian
BT Tech
305-652-3115

 

I'm glad you've stopped lurking, krazyglue. Now we know who you are.

The BT Tech plate makes a world of difference in the handling of my Prius. With the hard anodized finish, I'll chance it turning into a bigger battery then the HV one.

Do you have a Prius? Thought not.

What are your engineering credentials?

 

krazyglue,

That's a valid concern, but you might have phrased in such a way that you weren't suggesting that BT Tech was clueless. Clearly Brian had good reasons for not doing what you suggested. It's good to see that he had is reasons and stated them. Now everyone has a better understanding (at least I do) so in that sense it was a good post.

 

Actually, I raised the same question in another similar thread.
I am more concerned about the other party of contact, the Prius body frame. I would feel much better if another layer of antirust coating is spreyed on the contact area after installation to seal the contact in.

Thanks for BT Tech's answer. I learned a lot about anodizing aluminum. I surely will find more read about it thru google.

 

I think that's a valid point, although even if the paint and the coating on the stiffener were to wear through I think it would take a long time to cause damage. Then again, I don't live where roads get salted.

I should be getting my stiffener any day, it's in transit. Just to add another layer of protection when installing it I'll add some .015" mylar between the two mating surfaces.

 

What if a couple of rubber washers were used in attaching it?

 

I'd think rubber can deteriorate with the weather as well -- the mylar sounds like a nifty idea.

 

You are speaking of galvanic corrosion and this would only start to occur if BARE aluminum is contacting BARE steel. What I have explained is that we are not using uncoated aluminum but HARD anodizing.

We are not the first company in history to use an aluminum plate that is hard anodized to connect to a steel frame. This has been done for years and your concern though valid in theory is actually of very little concern in real world situations.

Obviously you have not seen how our plate is mounted to the vehicle. The top of the plate that attaches with 2 M8 stainless bolts on each side is practically sealing the top of the frame. If rain water or anything else for that matter were to penetrate this area this still would not be an issues as the plate is hard anodized and non conductive.

I suppose if someone was very concerned one could always attach a sacrificial zinc anode to the plate but this IMO is not required.



Thanks!!

Brian
BT Tech
305-652-3115

 

krazyglue, are you saying that the hard anodization will be broken or penetrated at the points of contact?

 

Brian rocks!

 

This is what I was going to suggest if someone was overly concerned. All big steel bridges have a huge chunk of zinc buried in the ground at on or the other end just for this purpose. I also don't think it's quite necessary in this situation.

 

I just picked up my Prius from the garage where they installed the BT stiffener. The mechanics were really excited to see a Prius and invited me to see the installed stiffener while the car's on the lift. The fit and finish of where the plate meets the chassis looked tight so I'm inclined to take BT Brian's assurance on that. And driving home I noticed the improved handling right away, (part of it is probably psychological). All in all it's a nice mod!

 

My aluminum parts on my hot engine (block, heads, etc) have steel bolts, steel exhaust, steel oil pan, steel brackets, zinc washers attached and operate about at about 250 degrees. Most aluminum parts elswhere are attached with steel bolts. My aluminum motor-generator is attached to steel bolts and brackets.
All with no rust, even at elevated temperatures.

So, I would not worry about the BT Tech plate to chassis interface.

200Volts
B.S. Chemical Engineering (anyone want to discuss EMF?)

 

First, my credentials -- I failed chemistry in college.

Second, a thought -- Doesn't a conductive element, in this case, water need to be present for galvanaic action to occur? Wouldn't the elevated temperatures evaporate any moisture thus prevent the effect?

Third -- Fools rush in where angels fear to tread.

 

Yep and keep an eye on it and replace as needed. Boats in salt water do it. hgas boy chemist. BS Chemistry The dean is still trying to figure out the exploding toilet seat with bronzed butt. I stand by all previous statements "I know nothing".
One of the things I learned growing up in Ohio is that with enough salt and water and time you will corrode almost anything, the question then becomes how much time salt and water? Will you have sold the car to someone else?

 

Well, I only have a minor in chemistry, but I think I know enough to say that it's very unlikely to be a problem to anyone here.

A boat is usually immersed in salt water all the time. A bridge is usually made of iron. THe zinc node is there mainly to prevent rust. The zinc corrodes before the iron does. I highly doubt that anyones Prius will be in the kind of environment where this could be a problem. If it is, there are a multitude of other components that would corrode just as fast or even faster and would cause major problems.

What it comes down tois if you're scared of the potential for the reaction, DON'T BUY ONE! If you're not, then do. It's that simple. I doubt it will ever be a problem, and so I ordered a brace.

 

Why can't one just put some sealant between the stiffener and the frame? I realize that the AL is anodized, but doesn't hurt to add sealant between the 2 parts.

 

I thought that was my point?! B)