Mercedes Clean Up

hingeman Wed Apr 22, 2015 1:08 am

The Mercedes was always a hard one to start! I haven't tried to start it since I cleaned it up but I can see now why it was so temperamental! Everything was froze up!

hingeman Wed Apr 22, 2015 1:25 am

More of the clean up.

The drive train works, engine is free with good compression, new needle valve, hood latch works, got all the crap out of the tank and tiny passages and the rear suspension is working now. The main thing that still needs help is the front suspension. I'm not sure what to with the broken mounts in the bottom half of the car. Any ideas?

getback Wed Apr 22, 2015 8:12 am

Nice clean up job And WELLCOME TO THE FORUM !! if it were me I would glue a plastic plug it there try and pull the cracked plastic together as best can and redrill for the screw ,, Rsv1 (Bob) or Mark will probably chime in with some ideas that they have used before . Eric Babe Bee .049

JasonB Wed Apr 22, 2015 9:29 am

Great job on cleaning that up!

Many such car bodies were made from polyethylene or polypropylene, and neither plastic glues very well. I've repaired similarly split screw posts on a good number of machines using the technique I'll describe here:

Clean the plastic well with a solvent that works for you. I like methanol or coleman fuel, but test to be sure it won't strip any paint or melt the plastic.

First, I'd make the top quarter-inch or so of the posts free all-around, by cutting back or (better) drilling passages thru the webbing on their sides. Then, I'd tightly wrap the posts with steel wire (very fine tag wire is great), tensioning the wire to draw the plastic splits back together as I went. Once as much of the post as possible was so bound, I'd twist the ends of the wires together tightly, and soak the wrapping in thin CA glue. Done neatly, it's strong and not bad looking. It can also be done with thread or monofiliment, but I've found tag wire to be best.

When dry, I'll coat the screw threads in wax, put a dab of epoxy down the screw hole, and assemble. The wax on the threads will make the screw removable, while the epoxy will ensure good thread grab if the hole was previously stripped at all.

This style repair is holding together a few models and my dishwasher door right now...

J

hingeman Thu Apr 23, 2015 3:38 am

That's a great idea if you have something to work with. In my case, the pieces are broke off and gone. Here's some pics.

,

,

The last 2 pics are the hood, hood hinge and nose piece. The grill is removed for the pics. I'm thinking that I have to find some red plastic and try to fab something up. Any other ideas? Maybe fill the bosses (what's left of them) with epoxy and drill them out? Whithout a fix, I can't even sit the car on all 4 wheels without putting way too much stress on the remaining parts. Thanks for your help!

getback Thu Apr 23, 2015 8:17 am

sorry I didn't notice the ones that were completely missing // I would think that other toys are made in the same way with plastic bosses , maybe you could find something cheap at the local toy department and cut them off it to repair yours ?? just thinking out loud , hope you can get it repaired .

JasonB Thu Apr 23, 2015 8:51 am

I see. That's more difficult Sad

I'd be tempted to make a pair of plastic blocks that I could screw to the bottom of the pan after removing the remains of the old bosses. Whittle/drill/shape them until they'll do the job.

Alternatively, drill/score the existing remaining plastic, and create some temporary dams using tape or whatever. Cast epoxy up to the top of the boss level. Might help to embed some wire in a circular fashion around where the screws will need to go as "rebar" to toughen the epoxy, or use epoxy mixed with fibreglass chop. Once set up, drill and tap for screws etc.

That's the best I can think of, short of sourcing a replacement part.

J

rsv1cox Thu Apr 23, 2015 10:07 am

It's too bad that the broken pieces are missing, if you had them I find that Testors red tube plastic cement works well on non stressed structures. Looks like yours is a compression fit. You could Dremel them flat and construct a replacement block out of hardwood or plastic then drill out and bush if necessary.

That is one fantastic looking machine and well worthy of reconstruction.

roddie Thu Apr 23, 2015 10:08 am

I think the answer is in a whole different retention system that bypasses the broken bosses completely.. but still be easily removable for service. You might try cutting a block of balsa (or laminate balsa sheets into a block of the correct shape/thickness) for inside the chassis.. seal and paint the block gloss red or black.. and apply stick-on hook & loop to the top and bottom plastic surfaces to hold it all together. Alternately.. you could use Neodymium (rare earth) magnets which are very strong.. if you can find a way to adhere them to the plastic. The inner block would need to be the proper/precise thickness for this to work either way.

The front axle is free floating and held in place by the top and bottom pieces.. correct?

hingeman Thu Apr 23, 2015 1:20 pm

roddie wrote:I think the answer is in a whole different retention system that bypasses the broken bosses completely.. but still be easily removable for service. You might try cutting a block of balsa (or laminate balsa sheets into a block of the correct shape/thickness) for inside the chassis.. seal and paint the block gloss red or black.. and apply stick-on hook & loop to the top and bottom plastic surfaces to hold it all together. Alternately.. you could use Neodymium (rare earth) magnets which are very strong.. if you can find a way to adhere them to the plastic. The inner block would need to be the proper/precise thickness for this to work either way.

The front axle is free floating and held in place by the top and bottom pieces.. correct?

That's correct, roddie. It was a poor design from the start in my opinion. It puts way too much stress on the bosses in the bottom half as well as the top half. The rear suspension seems stronger but it has its design problems as well. directly in front of the rear gear box, it has a 1/4" notch that allows it to move up and down in between the notch. The manual says it was intended to do that but it sure seems like it moves around a lot when turning the rear tire to start the engine. That's probably why my "Prop Rod" was my favorite car! It always started. Hey, maybe that's why my hearing sucks now? Da! I wish it had an odometer on it because I used the heck out of it in our garage! Thanks again for all the comments, welcomes and help from everyone! I think Mom has a big smile on her face as well! Scott

hingeman Sun Apr 26, 2015 4:44 pm

I ground down the old bosses but left as much as I could so the new plastic tubing would fit inside for more support and to keep them in the right spot. I roughed up the tubing and cleaned with alcohol so the Gorilla epoxy would adhere to it. I used a plastic coat hanger for the screw mounts and epoxied them in as well. It seems to be very strong and didn't budge when I was drilling and screwing the long body half screws into them. I can push on the front body now and the independent front and rear suspension works really well and smooth just like it did 50 years ago! Thanks for all the help, ideas, and encouragement. Without it, it would still be collecting dust in a box in the attic! Small Cox Logo

hingeman Sun Apr 26, 2015 4:59 pm

Next on the list is to rechrome the side pipes and find new #9 stickers. Scott

roddie Sun Apr 26, 2015 5:06 pm

WOW!!! Awesome job Scott! Thumbs Up

What a great looking machine!

dckrsn Sun Apr 26, 2015 6:24 pm

Excellent job!
Keeping a piece like this alive, would put a smile on
anyone's face(at least around here). Thanks for doing
it, and sharing the project.
+
Bob

**Cribbs74** Sun Apr 26, 2015 8:11 pm

Good job! I do hope you plan on running it at least one more time.

NEW222 Sun Apr 26, 2015 8:48 pm

Looking good. Fix looks well also.

getback Mon Apr 27, 2015 6:57 am

Scott That looks FANTASTIC Glad you got that figured out and fixed , If you do run it please post a video if you can wee don't get any people on here posting car runs much . I am thinking of a inexpensive ? cox or so car to run not sure yet what though // Prop Rod or Geared I am thinking the Prop Rod would bee easier to get going if missing pieces Smile

Eric

hingeman Tue Apr 28, 2015 3:23 am

getback wrote:Scott That looks FANTASTIC Glad you got that figured out and fixed , If you do run it please post a video if you can wee don't get any people on here posting car runs much . I am thinking of a inexpensive ? cox or so car to run not sure yet what though // Prop Rod or Geared I am thinking the Prop Rod would bee easier to get going if missing pieces Eric

That was the reason that I loved my Prop rod! There's nothing to it, a rolling car, engine and prop. It always started and we all had a blast with it. It would be nice to drill an anchor in the middle of the garage (like my Dad did for me) and let her go BUT, after 35 years in the same garage, there's no way I could make room for that!! I wasn't gonna start it because it will get it all dirty again but I think I'm changing my mind. I bought engine parts from cox int. but they weren't here yet when I put it back together so I still have to take the engine out again and put new gaskets etc. in it. Does any body use the "after you run engine oil?" Does it help? Scott

getback Tue Apr 28, 2015 7:38 am

Most of us do there was a discussion about it here but I cant find it , I use 10 W hydraulic fluid , air gun oil is the same and U don't have to buy 5 gal. Very Happy

Bill steklenski Wed Apr 29, 2015 5:32 pm

This car looks Great for considering its age and condition. I just passed up on a maroon one at the Lebanon PA Show this past March, I thought $500 was a little more than I wanted to put out for a runner. I have had good luck soaking old Engines in rubbing alcohol and brushing it on the Styrene Type plastic when cleaning old Cox Models. There also is a product called Q bond which works very well around mounting stems and bosses. I actually used some JB Quick weld inside my Cox Ski Doo chassis, ( the Runner), . Keep up the great Work, We cant wait to Smell the nitro!

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