Start of MII install, now the official thread

...:Handshake...

 

Just looked at the new RCM kit I'm putting in my Rambler, Willie has added some stiffener plates to the crossmember instead of gussets. Either way, I can't imagine them pulling out...

 

I see mine have them also...

 

Turns out I have the 1 3/8" spools.

I'm going to gamble and say that the spools are on plates possibly to make assymbly easier for them as they put it all together. I would think welding the spool directly to the xmember is stronger than having a plate that can split away or flex. Maybe they added the plate over the spool that was already welded and then welded the plate to the spool. Doing that though they would have had to do a fill weld. I can't tell from the pics. Can you see inside the xmember from the bottom (or from anywhere) by chance?
I am guessing that spools are being used instead of using one solid tube piercing through the xmember. That would be as strong as you could get. The drawback is that the bolt will most likely get stuck.

 

Before I finally did the MII conversion, I read up on the subject. There were certain failures noted to the wide lower A-Frames but it had to do with the single long bolt failing and not the cradle or the A-Frame itself

 

I've read enough about them, to not want a Mustang II conversion.

 

Musta been some early stuff. I can't see these monsters that are also hardened breaking. They are like 5/8 or 3/4..

 

if you're building a "show car" what's to worry...

 

I'm not building a show car, that's the reason.

 

I use these wild offset (to the rear) lower control arms built by Full Tilt Steet Rods which give me an oportunity to use 2 bolts per side instead of one long one - the owner at Full Tilt did tell me that he thought it was overkill as their single long bolt has never given anyone problems but he saw nothing wrong with going with the 2 bolts per side

 

The RCM lower tube is one-piece, full length...

 

I wasn't referring to the bolt failing. What fails is the weld rips out of the sheetmetal where the crossmember welds to the bottom of the frame rail. I tried to get into a thread about this on the H.A.M.B. that has pictures but the site was down for maintenance.

The tab I am referring to, the bolt goes thru the tab before going into the pivot point of the a-frame or crossmember so you are adding a leg from the very end of the bolt to the sheetmetal lower part of the frame rail again. It will keep the bolt end from rotating up and down as you apply the brakes.

It has nothing to do with bolt strength, it all about the lack of strength in the actual crossmsmber/frame rail connection. Remember, the MII uses a strut to counteract the forces of braking just like a Mav does. When you go to a strutless lower, you loose the support during rotation and eventually rip the crossmember out of the bottom of the frame. That's why the tabs from the end of the bolt to the frame rail help.

Food for thought, there are a lot of strutless lowers running around fine but in the street rod community, where this technology has been used for 20+ years, they are seeing issues.

Go to the very bottom of this post and it will show a tab added.
http://www.clubfte.com/users/jniolon/mustangIIinstall/mustanginstall.html

Google "mustang ii crossmember failure" and it will bring up the pics on the H.A.M.B. but you cannot open the posts right now. Look for tabs running from the ends of the bolt to the frame , there are several examples.

SPark

 

I've never seen this "tab" design, and as stout as the RCM crossmember is, I feel the frame rails themselves (being sheetmetal) are now the weakest link. The only MII failures I'm aware of involve the lower A-arm tubes pulling out. I know the RCM crossmember is 1/4" wall 2" x 4" tubing, and their newer design has an additional piece of plate welded against each side so the bolt tube passes through a much stronger mass. I just don't see the lower tubes pulling out of that. Other MFG's and designs may not be as sturdy...

 

Like I stated above, it's not about the bolt pulling out of the tube, it's about the crossmember pulling out of the sheetmetal as it flexes during braking and cornering. The short tabs at the ends of the bolt help to stop the flex.

I've seen bent bolts after a few miles use but never seen one pull out of the crossmember. Long bolts bend easier than short ones do.

SPark

 

The tab is interesting.. Obviously any added ridgid points will increase the stability so I'll chew on the "food for thought". Thanks for showing it.