Unwarp system case side?

[barrys]

My bike is a 2002 R1150RTP. The bags were miserable and I'm replacing and rebuilding.  On one side, the case half on the bike side is warped on the seal where the halves meet and the cover pinches the rubber and makes it hard to close.  It's not a big deal and you can't even see it.  I just got pristine city lids and I'd like to straighten it.  It's just on the bottom edge and the curve is even as if someone left something heavy in there and left it in the sun for a few years.  See pic.  It's not that bad but it's bad enough to make other stuff break eventually.

Any ideas on how to unwarp that?  I know that molded plastic has memory and I'm thinking about baking it for 5 minutes at 350 F to perhaps soften it.  I'm afraid a heat gun won't give enough even heat and the sun won't do anything. 

 

I think this has probably happened to other oilheaders.  I'm definitely getting sick of buying case parts on eBay...

[dirtrider]

35 minutes ago, barrys said:

My bike is a 2002 R1150RTP. The bags were miserable and I'm replacing and rebuilding.  On one side, the case half on the bike side is warped on the seal where the halves meet and the cover pinches the rubber and makes it hard to close.  It's not a big deal and you can't even see it.  I just got pristine city lids and I'd like to straighten it.  It's just on the bottom edge and the curve is even as if someone left something heavy in there and left it in the sun for a few years.  See pic.  It's not that bad but it's bad enough to make other stuff break eventually.

Any ideas on how to unwarp that?  I know that molded plastic has memory and I'm thinking about baking it for 5 minutes at 350 F to perhaps soften it.  I'm afraid a heat gun won't give enough even heat and the sun won't do anything. 

 

I think this has probably happened to other oilheaders.  I'm definitely getting sick of buying case parts on eBay...

 

 

Afternoon Barrys

 

That is one of those deals that you almost have  have hands on to make an informed suggestion.

 

Heating & trying to recontour might work, OR, it might make it worse.

 

First thing that comes to my mind is to bond a strap of metal about 3/4" wide to the inside of that warped area to force it straight. Probably use a plastic-to-metal super bonding adhesive like used to bond plastic/composite  auto fenders & panels  to metal auto chassis.

[barrys]

Afternoon and thank you.

That's an interesting idea.  It seems that bonding strips of metal to plastic is how most people implement all kinds of system case repair.

I'm not looking forward to sticking the thing in an oven for all kinds of reasons.  I also see that I can run longer rivets at the hinge locations to secure the reinforcement.  I pulled the rivets for the city lids and I'm waiting on replacements.

 

(The rivets are 5/32 x 3/4 pop rivets for anyone shopping.  100 pieces for 12-15 bucks at Fastenere.com or amazon. )

My jury is out on how well my previous owner respected his or her underwear.

Edited August 7, 2019 by barrys

[barrys]

Where the bag is warped is the reinforced part on the hinged edge.  I can't think of any thin strip of metal - say 1" x 1/8 or 3/16 - that would be strong enough to overcome the tension of that warp.  I could use cold rolled steel but that's no fun to work with.  Let's see what other ideas are suggested.

[Miguel!]

L or R side? I hqvc a damaged L case you can have for parts but both sides of the case have damage but its not warped, Miguel

[barrys]

That's very nice of you.  It is the left case.  I'll send you a message with contact info.  Nice RT.  I love that color.  A local rider has one and I see it often.

[barrys]

Well, having a forum member gift you a used part in great condition is clearly the best possible repair... Thank you Miguel.  How awesome.  I'll swap the covers -- which I'm getting good at -- and all is well. I love forums.. Especially the kind with BMW motorcycle geeks.

 

Might still want to unwarp the old case back to use with the big lids.  I'm thinking of combining the heat and the metal support ideas.  I would make a temporary metal support that works the curve in the other direction.  With that clamped on, heat might allow it to move just that surface without turning the whole case into a potato chip.  I'm also wondering if heat will ruin the multi-box.  It will at least make the grease go away and you kinda have to tear it down to re-lube.  Maybe heat gun...

[dirtrider]

37 minutes ago, barrys said:

Well, having a forum member gift you a used part in great condition is clearly the best possible repair... Thank you Miguel.  How awesome.  I'll swap the covers -- which I'm getting good at -- and all is well. I love forums.. Especially the kind with BMW motorcycle geeks.

 

Might still want to unwarp the old case back to use with the big lids.  I'm thinking of combining the heat and the metal support ideas.  I would make a temporary metal support that works the curve in the other direction.  With that clamped on, heat might allow it to move just that surface without turning the whole case into a potato chip.  I'm also wondering if heat will ruin the multi-box.  It will at least make the grease go away and you kinda have to tear it down to re-lube.  Maybe heat gun...

 

Evening barrys

 

That is going to be a difficult repair to get the thing straight again (even with a backer) but if I were the one doing it I would probably use steam rather than a heat gun. Steam allows even continued heating without burning the plastic or causing unintended  nearby plastic distortion.

[barrys]

I have a friend with a upholstery shop and he has a great steamer.  How would you apply the steam?  Back and forth like a heat gun?

[Skywagon]

IMHO just heating/steaming on it's own won't do anything.  You need to get it to the shape you want it before you apply heat.  Without seeing what you have here is my thought.  I would rig up a couple of 2x4's with some sort of C-Clamp on each end allowing you to apply pressure where needed to pull it back in line.  The perhaps steam/heat might cause it to hold the shape you put it in.  You might have to do it in small increments depending on how much bend you have.  In lieu of clamps a couple of longs studs and washer that you can tighten in each end of the 2x4's could work.

[barrys]

That's exactly what I had in mind.  I should have been clearer with:

 I would make a temporary metal support that works the curve in the other direction.  With that clamped on, heat might allow it to move just that surface without turning the whole case into a potato chip. 

Maybe you only saw the last post.

I can make a clamping block with the slight curve I want to push the curve the other way.  I can even make it an adjustable curve with a block in the middle and clamps at the ends.  Then I guess just steam and check.  If the steam doesn't do it (and that part of the plastic is heavily reinforced) I break out more serious weapons.

[Selden]

Adding my 2 cents, if the cases are made from ABS, the softening point should be around 221°, so steam may not quite get you there, although it's certainly a safe, non-destructive starting point. That said, I have "straightened out" warped plastic parts (not on system cases) using a similar technique of a strong brace and C-clamps, sometimes bending to a slight reverse curve to get the desired result when the jig is removed.

[barrys]

I was worried steam might not be hot enough.  I agree it sounds good because it's delicate.  I think we have a quorum on how to apply pressure.  I'll start with the heat gun.  I have 50K BTU farmer's butane torch.  I think we'll leave that on the shelf...  Even if I bubble it, it's a spare part now -- thanks to Miguel -- and the damage will be inside.  "The customer will never see that."

 

Thread digression alert.

 

P.S. Skywagon, Did you or do you fly a "Warthog" fighter jet?  That would be cool indeed. I do like that plane.  At the risk of pushing my luck, it seems like perhaps the oilhead of aircraft.  Versatile, reliable, and fun to drive.  I'm not an aviation guy but hasn't that aircraft been in use as long or longer than any other?  I'm sure many forum members can respond on such topics.

[Skywagon]

Barry...yep Warthog pilot from another time.  Flew lots of things..  The hog was and is an incredible airplane. The amount of fire power it could deliver with those 30mm cannons, the amount of fire it could take, keep the pilot safe, and still fly was amazing. Ive seem some pretty shot up A10's that made it home that should not have. In my opinion, and in most ground pounders, there is no better forward air combat plane than the A10.  Ive been on this site since 2007 I think and you were the first to inquire.

[barrys]

Glad I asked.  Everything you said just seemed intuitive to me and I only saw one in an airshow once and never read a thing.  It was the star of that air show -- 90 degree roll right, tight clockwise 360s way close to the deck.  I'm not going to make up numbers.  To me it was wild and really loud which is kinda why I like motorcycles.  30mm is crazy.  I work with stock like that on my lathe.

[barrys]

To finish beating a dead horse...

I fixed the warped case today -- in 10 minutes after all of this -- and it looks great.  Quick summary if someone else tries this someday.

Stuff:

Heat gun.

Temp gun - optional.

Clamps - two 3" metal c clamps.

Hard straight edge -- 1' of 1" u-channel steel.

Drill bit with the diameter = twice the distance that the case bows from a straight line which is where you want to end up -- about 3/8" in my case.

The bits one step smaller and larger than the one above.

 

Use anything you want to apply pressure in a curve agains the bow you're trying to relieve.

I used drill bit shafts to get the curve I wanted so I could heat both sides of the plastic. 

  The plastic is very soft at room temp so the clamps will almost be loose enough to fall off.

  One drill in the middle and one on each side moved so the curve is opposite the original bow -- don't sweat this too much.

Heat both sides.

  I went to about 215 F and held it there for a minute or so.  Back side was about 170.

  I used a temperature gun but perhaps a drop of water might tell you when you get to temp.

I left it for 10 minutes and it was perfect.

 

I need to think less and make more mistake like I used to when I was younger.  I tore into everything and that was a lot more fun.  Engineering jobs can hurt you.