Ok guys, here's your chance to one-up the Honda engineers.

I spent a little time this evening cleaning up the broken rear subframe crossmember on my little CRX. Since I've decided to go the repair route (instead of replacement), I wanted to gather some input from the smarter and more experienced H-T members on a good course of action.

After considering a few options, here's the plan I have come up with to "weld the sumbitch back together":

1) Stitch weld the subframe back to the unibody and weld up the large crack in the middle. (Red lines)

2) Add a piece of angle iron welded to the x-member to prevent the large crack from weakening and re-opening.



3) Weld the cracks above the LCAs shut.

Driver Side (looking up from below the LCA):

Passenger Side (from the rear):


4) Add a couple of plates and a triangulating bar or tube between the outside of the LCA mounts and the frame rails.




I have a few concerns (here come the questions):

1) Will this change in load paths of the suspension affect suspension behavior at all?

2) Should I rosette weld the angle iron, stitch weld it, or both?

3) What is the preferable material for the bar between the LCA mount and the frame rail? Tube? Box iron? U-channel?

As always, thanks for the advice.

-- Jon

 

there may be some legality issues with the extent of the repair...depending on the class you are running.

Check into that before you lay any beads.....

 

Wow, that is really futched. But I agree with Jeremy that you need to check your rules because I don't see your plan being IT legal. I had thought of support bars but going inboard and not outboard as you show. I would think your damage was cause by thrust or impact moving the wheel inboard and not pulling it outboard. I am not structural engineer by any means but I would thin you want you bars in compression and not stretch.

I am not a welding expert either but here is what I had visualized. First weld up your cracks themselves which I would think is not really going to be that strong but will help. Then stitch or bead weld the entire edge of the subframe that you can to the pan and chassis by simply going around the outer edge. Then take a piece of rectangular sheet and form it to fit as a large patch over the three sides of the crossmember memer in the middle to cover the center crack and maybe add small wings to let it spread a bit up into the floorpan as much as reasonable. Cut a few small holes here and there to rosette it to the crossmember in addition to stitching or bead around the edge. My support bar idea would then be to run a 12 inch or so long bar from the middle of that new sheet patch out to the back side of where each LCA bolts up to the crossmember. You would want to weld a small plate to that back side to bear load then weld the end of the tube to it. I don't know any drawing programs like you used but I forsee a tube rubbing from the back side of the LCA mount on the crossmember up to a the middle area where your crack is now. This would look like a shallow inverted V shape to the LCA pickups. This would resist and spread the load on force and impacts from the side being applied toward the center of the car and down the LCA and into the crossmember and trying to shove it toward the middle of the car. Let me know what you guys think.

I have seen a similar LCA mount support welded to a front crossmember/steering rack holder on an ex-Firehawk CRX that later won the ARRC in ITA and kicked my butt in Cen-Div. When the car was crashed and killed, I saw parts of it stripped and a few hidden supports like this became obvious.

 

As far as IT rules are concerned, you can repair damage but you can't *improve* the structure while doing so.

So, welding the cracks and then covering them with plates or angle = Legal.
Adding braces and supports = Not legal.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Catch 22 &raquo;</TD></TR><TR><TD CLASS="quote">As far as IT rules are concerned, you can repair damage but you can't *improve* the structure while doing so.

So, welding the cracks and then covering them with plates or angle = Legal.
Adding braces and supports = Not legal.</TD></TR></TABLE>

Unless the braces are part of the repairs.. Its a huge can of worms..

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Honda318dx &raquo;</TD></TR><TR><TD CLASS="quote">

Unless the braces are part of the repairs.. Its a huge can of worms..</TD></TR></TABLE>

Not really.
You can't put a brace where there previously wasn't a brace and call it a repair.

In other words, you can patch a hole or a crack, but you cant triangulate the area with angle and call it a "repair."
Thats not a "repair," thats an "improvement."

 

Did you run a rear lower tie bar before? From the photos, it does not look like it. It is legal and one side will help support the other to share the loads that you put through it.

Just a thought...

 

Are you sure its not cheaper and less time to just drill all the spot welds and put a new subframe in. We did this with my Civic and I don't think that was the wrong call at all. After you clean off all the cracked areas to weld, line everything up and reweld it, you'd probably be at the same place. For $122 is it worth all the effort to repair the old one? I could understand repairing until I saw the cracks on both ends of the subframe too. How easy will it be to work in those little areas too?

Just my .02

 

you missed the other thread. crossmembers are no longer available.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RexRacer19 &raquo;</TD></TR><TR><TD CLASS="quote">Did you run a rear lower tie bar before?</TD></TR></TABLE>

Nope, no tie bar. I've looked into the options though and I thought about ordering the Neuspeed bar. However, my big concern is that it will add stress to the already-cracking mounts above the LCAs, which are clearly a weak point of the CRX suspension design.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Catch 22 &raquo;</TD></TR><TR><TD CLASS="quote">
You can't put a brace where there previously wasn't a brace and call it a repair.

In other words, you can patch a hole or a crack, but you cant triangulate the area with angle and call it a "repair."
Thats not a "repair," thats an "improvement."</TD></TR></TABLE>

Hmm. If the 'repaired' part is guaranteed to fail without reinforcement, however, could it be argued that the 'improvement' IS in fact part of the repair? If there is no competitive advantage gained from that improvement, does it matter? Clearly, if I were protested, that would be a "gotcha" for the inspector. I just want to make sure I can argue my case...

I would analogize an extra brace for the LCA mount to a bolt-in subframe tie bar back there, which I can only assume is legal in SCCA. It's a reliability part, not a performance part. If I made my extra brace bolt-in, would it be allowable then? If I drove a quick slalom around my block and broke those upper mounts the rest of the way, would I THEN be justified in building my brace? Can o' worms...

Thanks for the feedback, keep it coming!

-- Jon

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Catch 22 &raquo;</TD></TR><TR><TD CLASS="quote">Not really.
You can't put a brace where there previously wasn't a brace and call it a repair.

In other words, you can patch a hole or a crack, but you cant triangulate the area with angle and call it a "repair."
Thats not a "repair," thats an "improvement."</TD></TR></TABLE>

I would agree with Scott here. This is the way these things have gone in the past. Adding to the stucture is a good way to get protested & a DQ

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Sterndotstern &raquo;</TD></TR><TR><TD CLASS="quote">
It's a reliability part, not a performance part. </TD></TR></TABLE>

Doesnt matter - rules is rules.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by civicrr &raquo;</TD></TR><TR><TD CLASS="quote">you missed the other thread. crossmembers are no longer available.</TD></TR></TABLE>

then find one in a salvage yard and salvage it.

 

one thing you should do is drill a small hole in the end/beginning of the crack. otherwise, even with welding up, they are likely to propagate.

something just like 3/16" or 1/4" right where it seems to end should help.

tom

 

For the modification I discussed, I would think you would have a better chance of calling it a repair since it is essentially self-contained and would not extend outside the original attaching dimensions of the subframe. I am not really a fan of the strut rod from one LCA mount to the other as it certainly would spread some load but it is still being spread to the other known weak spot and not to the actual shell of the car.

For my Prod car this is all somewhat moot as I am allowed reinforcements that an IT car is not. I though early in the other thread it said that a new replacement subframe was not available for the CRX.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by CRX Lee &raquo;</TD></TR><TR><TD CLASS="quote">For the modification I discussed, I would think you would have a better chance of calling it a repair since it is essentially self-contained and would not extend outside the original attaching dimensions of the subframe. I am not really a fan of the strut rod from one LCA mount to the other as it certainly would spread some load but it is still being spread to the other known weak spot and not to the actual shell of the car.</TD></TR></TABLE>

Good point about your repair plan, that bumps it up as a possibility. About the strut rod/tie bar -- my thoughts exactly.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by .RJ &raquo;</TD></TR><TR><TD CLASS="quote">Doesnt matter - rules is rules.</TD></TR></TABLE>

Rules are rules, unless the rules are vague and open to interpretation. It's a matter of degrees in this case -- to repair the problems, you'll need at least several sturdy patches. Arguably, these patches won't do much to prevent further damage to this part without some added material to brace.

Frankly, I don't give a good god damn if I get protested. I'm not about to allow a catastrophic failure in the rear subframe to occur that could cost me my car, my health, or my life. I'm out to design the best repair possible. However, if I want to run the car with SCCA or sell it, I also want to make sure my repair is the "closest to legal" that I can make while ensuring the part IS ACTUALLY FIXED.

-- Jon

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Sterndotstern &raquo;</TD></TR><TR><TD CLASS="quote">If the 'repaired' part is guaranteed to fail without reinforcement, however, could it be argued that the 'improvement' IS in fact part of the repair?</TD></TR></TABLE>
The rules refer you back to the manufacturer's service manual. Whatever is the approved process in there (or via TSB) is allowed in SCCA. However, if there is no approved repair procedure for that part then the only IT-legal option is to replace it in whole.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Sterndotstern &raquo;</TD></TR><TR><TD CLASS="quote">If there is no competitive advantage gained from that improvement, does it matter?</TD></TR></TABLE>
To an inspector ruling on a Steward's action or a protest, yes. You would be found illegal.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Sterndotstern &raquo;</TD></TR><TR><TD CLASS="quote">I would analogize an extra brace for the LCA mount to a bolt-in subframe tie bar back there, which I can only assume is legal in SCCA.</TD></TR></TABLE>
Incorrect assumption. I can think of no rule that allows a rear lower control arm brace. The *only* way you could get around this is if you designed something that incorporated the allowed rear swaybar, and even then you may be bumping up against the "prohibited function" clause.

You want the absolutely safe advice? Find one from a salvage yard and replace it. Anything else is inviting unwanted scrutiny. - GA

 

With all the cracks that are shown, my money would be on replacing the subframe entirely. New would be preferable but used from a salvage yard should suffice if new is not available. Any decent body shop should be able to replace this for a reasonable sum since there is no precise painting required. The shop manual should show how to locate the part on the chassis.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Sterndotstern &raquo;</TD></TR><TR><TD CLASS="quote">Nope, no tie bar. I've looked into the options though and I thought about ordering the Neuspeed bar. However, my big concern is that it will add stress to the already-cracking mounts above the LCAs, which are clearly a weak point of the CRX suspension design.</TD></TR></TABLE>

If anything, I would expect a tie bar to reduce the stress on the upper/outer area. The way it is stock, cornering forces push in on the LCA mounting point, which makes it try to pull the upper part of the subframe away from the body. Adding a tie bar should transmit some of that force over to the inner LCA mounting point and reduce the stress on the upper part of the outer side.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by CRX Lee &raquo;</TD></TR><TR><TD CLASS="quote"> I am not really a fan of the strut rod from one LCA mount to the other as it certainly would spread some load but it is still being spread to the other known weak spot and not to the actual shell of the car.
</TD></TR></TABLE>

But that is the benifit of sharing the load. If one side is weak...then two weak sides combine to make a stronger "group". That eases the burden for just one side to handle. As far as it being an "ultimate" solution...no it is not...but it is legal and should increase the longevity of that subframe.

 

Ok, from the overwhelming response I'm going to rule out adding a bar to triangulate the LCA mount with the frame rail. It sounds like it's going to be just plain illegal.

That said, I still plan to put some sturdy patches on the subframe above the LCAs to keep them from breaking again. However, they will be patches and not additional bracing of any sort.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ITC Racer &raquo;</TD></TR><TR><TD CLASS="quote">With all the cracks that are shown, my money would be on replacing the subframe entirely. New would be preferable but used from a salvage yard should suffice if new is not available. Any decent body shop should be able to replace this for a reasonable sum since there is no precise painting required. The shop manual should show how to locate the part on the chassis.</TD></TR></TABLE>

Salvage is out for this. It's probably going to be more sturdy and less expensive to repair the part.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RexRacer19 &raquo;</TD></TR><TR><TD CLASS="quote">But that is the benifit of sharing the load. If one side is weak...then two weak sides combine to make a stronger "group". That eases the burden for just one side to handle. As far as it being an "ultimate" solution...no it is not...but it is legal and should increase the longevity of that subframe.</TD></TR></TABLE>

I agree that it is sharing the load and spreading across more welds, etc. and it better then nothing. But it is spreading it to the next known weak point instead of a known stronger point.

The other thing I now like more about my inverted shallow V braces (which are legal on my car) is that it gives a great and easy chassis tie down location for trailering (see current trailering discussion).

Looks like we are all now aware of another part to consider saving when junking out a shell. I have a low mileage nose wrecked '89 CRX Si shell that I was going to cut the rear quarters off this Spring and now it looks like I need to save the rear crossmember if I can too.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by CRX Lee &raquo;</TD></TR><TR><TD CLASS="quote">
The other thing I now like more about my inverted shallow V braces (which are legal on my car)
</TD></TR></TABLE>

Darned IT rulebook...

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by CRX Lee &raquo;</TD></TR><TR><TD CLASS="quote">
Looks like we are all now aware of another part to consider saving when junking out a shell. I have a low mileage nose wrecked '89 CRX Si shell that I was going to cut the rear quarters off this Spring and now it looks like I need to save the rear crossmember if I can too. </TD></TR></TABLE>

And another area for the periodic maintenance list. If found early enough, it might be a lot easier to repair before it fails all together.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by CRX Lee &raquo;</TD></TR><TR><TD CLASS="quote">Looks like we are all now aware of another part to consider saving when junking out a shell. I have a low mileage nose wrecked '89 CRX Si shell that I was going to cut the rear quarters off this Spring and now it looks like I need to save the rear crossmember if I can too. </TD></TR></TABLE>

Let me know if you get it off non-destructively. I'm not sure that drilling out the spot welds is workable, since you'd want that material to weld it back up to a car. But this is pure speculation.

--Jon