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From: At my Bar drinking and wrenching in Lafayette Colorado
Half-century old fiberglass will develop cracks. Yes, that's normal. These cars were designed to last for about 10 years... That's why you need to be an "enthusiast" to keep them going...
To minimize the chances of cracks at the corners, when closing your hood, don't "drop" it closed. Instead gently lay the hood down, then press down at the center rear edge to snick the hood closed. Works for me, anyway.
To minimize the chances of cracks at the corners, when closing your hood, don't "drop" it closed. Instead gently lay the hood down, then press down at the center rear edge to snick the hood closed. Works for me, anyway.
I'm just the opposite. I lower it to about 6-8" from closing and then give it a pretty good slam. It's the only way I can get my hood to close to a consistent height even with the fenders. It sits up a little if I close it gently even though it's latched. Treating it like that doesn't seem to have any adverse affect.
I had cracks like that where you cant get behind them to fix them right. I ground a V about 1/4" each side and used JB weld (slow). haven't had them come back.
I have seen these type of cracks MANY times. I ahve seen the top hood surround in this area have different thicknesses due to the molds were not perfectly set-up every time. Sometimes I have had some in this curve be really thin fiberglass....while others were a comfortable 1/8" thick.
Like it was mentioned...it is an old car and there is no guarantee that the press molded panels are going to hold up for a century.
These cracks are not due to how the hood is closed due to the hood has nothing to do with the top hood surround. NOW if the cracks were on the hood itself by where the hinges mount...that would be an entirely different situation.
As for using JB Weld as an adhesive to fix cracks.. You all can do as you wish. I know that is not what I would use for this crack. .But I can tell you that any epoxy adhesive is extremely solvent sensitive...so just thinking that you can apply it and sand it down and paint it. I SERIOUSLY doubt that would work without some problems in swelling due to the solvents in the primer or paint got down to the epoxy adhesive. Can this method work...I guess it can. But I can tell you stories about me shooting primer on exposed epoxy adhesive and watch the area SWELL. So that is why I would not do it that way.
I have seen these type of cracks MANY times. I ahve seen the top hood surround in this area have different thicknesses due to the molds were not perfectly set-up every time. Sometimes I have had some in this curve be really thin fiberglass....while others were a comfortable 1/8" thick.
Like it was mentioned...it is an old car and there is no guarantee that the press molded panels are going to hold up for a century.
These cracks are not due to how the hood is closed due to the hood has nothing to do with the top hood surround. NOW if the cracks were on the hood itself by where the hinges mount...that would be an entirely different situation.
As for using JB Weld as an adhesive to fix cracks.. You all can do as you wish. I know that is not what I would use for this crack. .But I can tell you that any epoxy adhesive is extremely solvent sensitive...so just thinking that you can apply it and sand it down and paint it. I SERIOUSLY doubt that would work without some problems in swelling due to the solvents in the primer or paint got down to the epoxy adhesive. Can this method work...I guess it can. But I can tell you stories about me shooting primer on exposed epoxy adhesive and watch the area SWELL. So that is why I would not do it that way.
DUB
Dub,
Then I guess you do not use epoxy primer. Epoxy can go over glass, but glass is not recomended to go over epoxy.
Mine came out PERFECT and I did it in the 70's.
Dom,
YES.. I DO use epoxy primer. Yes I do also know about and use West Systems epoxy resin...along with knowing about the different types of polyester resin.
I do know epoxy primer can be used on fiberglass. But your post did not state any of this. Which is critical for those who read your post and do not know you used it and did not mention a CRITCAL step. Because using the wrong product on top of an epoxy adhesive can have very undesirable effects.
Such as...Knowing how much epoxy primer was applied and if it was blocked down and then re-applied. Then the type of paint applied on it. And if it was lacquer...if the thinner used allowed it 'flashed off' fast so it did not have any time to penetrate to cause swelling. I know these things and know how to do like what you did. SO I am NOT saying it cannot be done. It is just that JB Weld is not my chosen product to use in an area of repair like you chose to use it in. I use products that take the probability of a problem occurring out of the equation....or at least raises the level of success in my favor.
I never said JB Weld would not work.. I only passed along the facts of what can happen if it is not dealt with correctly.
Please understand I draw from decades of doing this stuff and I pay attention to how GM builds the bodies and where GM uses a two-part epoxy adhesive. They use it under the panel so none of it is exposed to the outer area where it will be seen in about 99.9% of the time.
Similar to back in the mid 80's. Basecoat/clearcoat was coming out and being used by the factory. Customers wanted their car to be painted in BC/CC. BUT...the paint companies had not yet made formulas for the old paint colors in BC/CC. So...we would shoot lacquer on it due to being able to get the correct color and then apply urethane clear coat over it to provide the new level of paint protection instead of using lacquer clear. That worked out perfectly fine UNTIL it got damaged and had to be repaired. Because applying lacquer on enamel that is still not fully cured can cause it to blister and wrinkle up UNLESS a person knows how to do it.
People can use what they want when they do body repairs. I know some methods work for some while when another person tries what some person has done... it fails badly. What is critical... is knowing all of what needs to be known so a person does not find themselves going down into the abyss.. THAT was all I trying to convey.
***On a side note***
It is really no different than you knowing all about A/C compressors and the problems that you have seen and know what works and what will not work and last. I would never question what you know to be true. Hopefully I have not tarnished my welcome and you would still rebuild an A/C compressor for my shop if needed like you have done in the past. Hopefully no hard feelings due to I feel I was not directly attacking you....nor am I implying that your comments were combative.
Dub,
Didn't mean my post to be taken that way. Only difference I see that we have about JB weld is that it is a resin and not a adhesive. Now in 1984 I quit my job and became a mtc forman at SIKA for 2 years where they make epoxy. Actually make the epoxy that we run over on the road that holds down those lane bumps. Pretty tough stuff to take that punishment. You guessed it, now put A & B in tubes, improve it a bit and call it JB weld. They did not make JB weld but knew it's formula. The lab rats also gave me the additive to make Duponts Centari into Imron! In the lab at SIKA they said that the epoxy resin in JB had aluminum mixed in with it. Only reason I thought I would share thatwith the guys is because it has worked wonders on my car cracks where there is no chance of backing the repair with cloth. It actually does not shrink like the other products that claim (won't shrink). I also painted all my life and appreciate the new products. we used to use lead till the better fillers came out.
One thing I shouldn't have said was you can't put polyester resin over epoxy resin. The lab forman said it was not a good practice but if you have to you need to use a very coarse grit.
I also think the WEST SYSTEM is great and use it to make fuel tanks in my molds and also behind repairs when they can be reached. I will say that I am still using old school spray guns. My favorite came from FORD in the 50's where my 2 brothers hand painted the new cars. The body shop was not for me, but I still do all my painting.
I am not trying to one up any one just sharing possible ways.
I m glad you passed long your experience in using what you did.
Like I wrote..it has worked for you and no problems. So..I have no problem with that at all.
YES..I guess I can now think of JB Weld as being a resin more than an adhesive....even though it is generally used to bond items together...much like the body panels I bond together. So...I am sure it is a difference in perspective.
The ONE major benefit you have over many of us...including me.... is that you got to rub elbows with the chemists that make this stuff and know about it. I am jealous. On rare occasions when I call tech lines I can get them to transfer me to the lab and can actually talk with a chemist who knows all about a specific product and how he/she tested it and what its limitations are...and not so much on what they put on paper to make sure people do not screw it up.
DUB,
There is a new group of tech reps out there that know about 1/2 of what the caller is asking. The lab rats were older men who kinda talked over my head. The manager of the epoxy department was my good friend before and to this day. He would put what they said into English for me. Unfortunatly the fresh out of school engineer burnt 1/3 of the mtc metal building building down. Part A and part B would cost over 500.00 a 55 gal drum to dispose of when it hit shelf life. If you mixed A & B together and it hardened you could put it in the dumpster! He had over 50 gallons of A & B mixed all at the same time. Well the A & B generated so much heat it caught fire. They had a guy stand there with a hose and keep it in check. when 5:00 came around we all went home except for the engineer, epoxy forman, and myself. At 5:30 the engineer said that it was safe to leave because only a puf of smoke was coming out.
Next morning !/3 of the building was gone along with the burnt mixers that were to be repaired.
I was using ACME acrylic enamel to paint a large radio controlled airplane and grabbed the laquer thinner can instead of the reducer. Paint came out great, but when I went to clean the gun I couldn't find the laquer thinner. That's when I found out I reduced the enamel with it. Paint shop tech said nothing would reduce the paint but ACME reducer! Could not dispose of partial cans of paint (EPA) so I mixed all my ACME, Dupont, and Ditzler together and painted my shelves asing laquet thinner. Paint tech said "no you didn't, they cant be mixed"!
Off the thread, but there are new tech people out there that only know what they read. Never squezed the trigger of a spray gun. I match painted the front of a airplane with the customers paint that he kept from the original paint job. Brand I never heard of and no window of time for re coat or striping. Tech couldn't answer only to say that 20 min was recomended between coats. Nothing about taping and painting the stripes window of time.
Dom
I haven't bought the car yet, just wondering how bad it is.
There is a metal bracket inside the wheel well that bolt to the back of the hood hinges and reinforce it.
Looks like this :
If it's rusted out chances cracks will form in the area.
I think if you turn the front wheels all the way out you can spot it.
This is a good point but a lot more than this bracket being rusted would cause those cracks.
The inner skirt would need to be badly cracked...and the support where the header bar for the headlights would need to be missing or not correct where it is secured to they front of the inner skirt.. Thus allowing the top hood surround to have flex...and then consider the front outer bumper mount areas also.
The photo alone only gives us the end result and nothing more than that. And until a visual inspection is made on it...it is hard to say what caused it or if it is a thin part of the top hood surround like I have seen before when it was made.
