'84 CGT Dash Rebuild progress - Step 1 (surface prep) (long thread)
01-22-2009, 05:15 PM
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'84 CGT Dash Rebuild progress - Step 1 (surface prep) (long thread)
<center><img src="http://pictureposter.audiworld.com/109615/dash_filler_step1.jpg"></center><p>
Well, I was going to wait until I was done, but everyone here is so knowledgeable I figure you all may have some good comments on technique while I'm repairing it...and to help me keep track while it's fresh in my mind.
I'll keep this tread going until I'm finished, which should be sometime on Sunday. So this will thread will either serve to document the right way, or the wrong way to repair a dash.
Here's the plan to rebuild and some reasons for the decisions I've made.
First let me start with my philosophy:
- it's already busted so I can only make it better
- the goal is not perfection as that's most likely unobtainable.
- attempting to make it better with an average looking finish
- color matching was not obtainable at this scale so I decided on black...you'll see why later.
- have fun learning as this is my first attempt at repairing vinyl (I've dealt with delamination before, but never UV damage).
- after extensive Internet research I found a lot of methods, but none of them held up more than a few days. My theory is that most of them attempted to use hard adhesives which didn't allow for flexing. They also didn't fully consider the effect of out gasing. Many Urethane adhesives have up to 10% VOC..those gases need to find a way out and most likely will cause pressure and crack the repair. One used silicone for the filler, but silicone really messes up any attempt to paint.
Current Condition:
- multiple cracks
- top of dash vinyl has turned to solid plastic and brittle...other areas not exposed to UV are in good shape
- underlying foam is in good shape and still adhering to the dash metal
- foam has deteriorated where the cracks have appeared
Concerns:
- the dash still needs to flex with temp variations caused by the sun after repair
- needed product with low to zero VOC to prevent out gassing
- needed to keep materials consistent to make sure they don't react with each other negatively (e.g. Urethane and styrene eat each other)
- didn't want any stinky fumes in the car after repair
Product selections:
- Caulk/adhesive - 3M 4000 Fast Cure Adhesive ($16). It has less than .02% VOC, remain flexible, has medium strength adhesion, is UV resistant
- Marine Vinyl repair kit ($17)...the automotive kit didn't contain enough repair material. The Evercoat kit has a role of vinyl and a lot of glue.
- Medium grit sanding sponge
- Rubbing alcohol
- Ammonia glass cleaner (nothing fancy, just straight ammonia)
- utility knife
- masking tape
- Duplicolor Vinyl and Fabric paint
- Duplicolor vinyl polymer truck bed liner
The Plan:
- Cut and fill cracks
- Laminate over 3M 4000 filler with vinyl sheets
- Spray with vinyl truck bed liner and use vinyl paint for color and texture matching
Repair method:
1. cut away puckering around cracks in a V pattern
2. remove all deteriorated foam from the cracks with knife
3. sand all dash surfaces...the foam block worked well and conformed to the dash contours. You'll know what needs the most sanding as the sanding block bites into hard vinyl, but not the good soft stuff.
3a. vacuum the dust and wipe down with ammonia cleaner...allow to dry completely
3b. I used strands of masking tape to determine if I sanded deep enough into the hard vinyl. If the tape stuck to the dash vinyl, then I knew I'd get good adhesion from the vinyl sheet cement. If it didn't stick, I didn't sand deep enough and gave it a few more passes.
4. Use the 3M 4000 to fill the cracks in a 2 step process
4a. use the nozzle which came with the 3M 4000 to fill the cracks almost level...DO NOT attempt to spread it immediately like I did. If you wait about 50 minutes (no longer than 1 hour) it will become the consistency of putty and is easier to work with (I tried to spread it immediately and it was unmanageable and very messy...remember, you're using this as a filler, not an adhesive). Dip your fingers in water as you work the "putty" into the crack to keep the 3M 4000 from sticking to your fingers. The 'putty' will be malleable to form ridges and troughs...much like working with clay. Dabbing with your fingers to flatten the 3M 4000 into the cracks works better than smearing. The 3M 4000 will sink a little, so don't try and get it perfect. Just fill the valleys and let the second coat be the finish coat. Use rubbing alcohol and a lint free cloth to remove the caulk from any areas you don't want it (within 1-1.5 hours or you'll have to use a knife after it hardens)
4b. Allow 24 hours for the first coat to cure, then spread another coat of 3M 4000 to smooth any inconsistencies within the 1st coat. You want to make it flush with the existing vinyl dash covering.
Conclusion so far:
- If I hadn't made such a mess spreading the caulk immediately after application it would have been much, much better. Now I have to use wider vinyl sheeting to make sure I get a good bond to the existing vinyl dash material.
Next steps:
5. Let 2nd coat harden over night
6. Cut strips of vinyl sheeting and cover the caulk with enough extending beyond the caulk to get a good bond vinyl sheet to dash vinyl. Also going to make sure it's taught to give a smooth texture...my test area worked well so it's promising.
6a. Possibly 'fair' any ridges along the vinyl sheet edges to get a smooth transition (I'm not sure how much the vinyl polymer spray will hide at this point)
7. tape the vent to protect them from the vinyl polymer spray.
8. Apply 2 coats of vinyl polymer spray
9. Apply one (maybe 2) coats of vinyl paint.
10. Apply a finishing coat of vinyl polymer spray
11. Mask dash and spray paint vents with vinyl paint.
12. Spray paint the other dash components with the vinyl paint for color matching.
I know it looks like crap right now, but I'm confident that it will look good after I'm done with it. We'll see how it all turns out! I'll keep you posted.
Well, I was going to wait until I was done, but everyone here is so knowledgeable I figure you all may have some good comments on technique while I'm repairing it...and to help me keep track while it's fresh in my mind.
I'll keep this tread going until I'm finished, which should be sometime on Sunday. So this will thread will either serve to document the right way, or the wrong way to repair a dash.
Here's the plan to rebuild and some reasons for the decisions I've made.
First let me start with my philosophy:
- it's already busted so I can only make it better
- the goal is not perfection as that's most likely unobtainable.
- attempting to make it better with an average looking finish
- color matching was not obtainable at this scale so I decided on black...you'll see why later.
- have fun learning as this is my first attempt at repairing vinyl (I've dealt with delamination before, but never UV damage).
- after extensive Internet research I found a lot of methods, but none of them held up more than a few days. My theory is that most of them attempted to use hard adhesives which didn't allow for flexing. They also didn't fully consider the effect of out gasing. Many Urethane adhesives have up to 10% VOC..those gases need to find a way out and most likely will cause pressure and crack the repair. One used silicone for the filler, but silicone really messes up any attempt to paint.
Current Condition:
- multiple cracks
- top of dash vinyl has turned to solid plastic and brittle...other areas not exposed to UV are in good shape
- underlying foam is in good shape and still adhering to the dash metal
- foam has deteriorated where the cracks have appeared
Concerns:
- the dash still needs to flex with temp variations caused by the sun after repair
- needed product with low to zero VOC to prevent out gassing
- needed to keep materials consistent to make sure they don't react with each other negatively (e.g. Urethane and styrene eat each other)
- didn't want any stinky fumes in the car after repair
Product selections:
- Caulk/adhesive - 3M 4000 Fast Cure Adhesive ($16). It has less than .02% VOC, remain flexible, has medium strength adhesion, is UV resistant
- Marine Vinyl repair kit ($17)...the automotive kit didn't contain enough repair material. The Evercoat kit has a role of vinyl and a lot of glue.
- Medium grit sanding sponge
- Rubbing alcohol
- Ammonia glass cleaner (nothing fancy, just straight ammonia)
- utility knife
- masking tape
- Duplicolor Vinyl and Fabric paint
- Duplicolor vinyl polymer truck bed liner
The Plan:
- Cut and fill cracks
- Laminate over 3M 4000 filler with vinyl sheets
- Spray with vinyl truck bed liner and use vinyl paint for color and texture matching
Repair method:
1. cut away puckering around cracks in a V pattern
2. remove all deteriorated foam from the cracks with knife
3. sand all dash surfaces...the foam block worked well and conformed to the dash contours. You'll know what needs the most sanding as the sanding block bites into hard vinyl, but not the good soft stuff.
3a. vacuum the dust and wipe down with ammonia cleaner...allow to dry completely
3b. I used strands of masking tape to determine if I sanded deep enough into the hard vinyl. If the tape stuck to the dash vinyl, then I knew I'd get good adhesion from the vinyl sheet cement. If it didn't stick, I didn't sand deep enough and gave it a few more passes.
4. Use the 3M 4000 to fill the cracks in a 2 step process
4a. use the nozzle which came with the 3M 4000 to fill the cracks almost level...DO NOT attempt to spread it immediately like I did. If you wait about 50 minutes (no longer than 1 hour) it will become the consistency of putty and is easier to work with (I tried to spread it immediately and it was unmanageable and very messy...remember, you're using this as a filler, not an adhesive). Dip your fingers in water as you work the "putty" into the crack to keep the 3M 4000 from sticking to your fingers. The 'putty' will be malleable to form ridges and troughs...much like working with clay. Dabbing with your fingers to flatten the 3M 4000 into the cracks works better than smearing. The 3M 4000 will sink a little, so don't try and get it perfect. Just fill the valleys and let the second coat be the finish coat. Use rubbing alcohol and a lint free cloth to remove the caulk from any areas you don't want it (within 1-1.5 hours or you'll have to use a knife after it hardens)
4b. Allow 24 hours for the first coat to cure, then spread another coat of 3M 4000 to smooth any inconsistencies within the 1st coat. You want to make it flush with the existing vinyl dash covering.
Conclusion so far:
- If I hadn't made such a mess spreading the caulk immediately after application it would have been much, much better. Now I have to use wider vinyl sheeting to make sure I get a good bond to the existing vinyl dash material.
Next steps:
5. Let 2nd coat harden over night
6. Cut strips of vinyl sheeting and cover the caulk with enough extending beyond the caulk to get a good bond vinyl sheet to dash vinyl. Also going to make sure it's taught to give a smooth texture...my test area worked well so it's promising.
6a. Possibly 'fair' any ridges along the vinyl sheet edges to get a smooth transition (I'm not sure how much the vinyl polymer spray will hide at this point)
7. tape the vent to protect them from the vinyl polymer spray.
8. Apply 2 coats of vinyl polymer spray
9. Apply one (maybe 2) coats of vinyl paint.
10. Apply a finishing coat of vinyl polymer spray
11. Mask dash and spray paint vents with vinyl paint.
12. Spray paint the other dash components with the vinyl paint for color matching.
I know it looks like crap right now, but I'm confident that it will look good after I'm done with it. We'll see how it all turns out! I'll keep you posted.
01-23-2009, 12:54 AM
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I'd think to spray the whole thing with an adhesive
like the 3M stuff in a can, then use a heatgun to stretch a piece of vinyl over it. I don' t know if the adhesive would be good enough, though.
01-23-2009, 04:14 AM
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I did some of that....
on my old boy, used the flexible filler, however followed the cure time with paint on the whole dash. it looked nice for about 3 years, then cracked/seperated again.
It was a PITA to get to all the cracks while the dash was in the car, which is how it did it....
I have bought a custon dash cover for the 4000, from a company some months ago. I havn't installed it yet, no time for it lately with the holidays and hunting season.
When I lay it on the dash, it looks pretty good, all the cut-outs are there. there's lots of velcor patches with it to hold it there, however I will likely use even more of velcro around the cutouts than they provided.
Good luck on your project!
It was a PITA to get to all the cracks while the dash was in the car, which is how it did it....
I have bought a custon dash cover for the 4000, from a company some months ago. I havn't installed it yet, no time for it lately with the holidays and hunting season.
When I lay it on the dash, it looks pretty good, all the cut-outs are there. there's lots of velcor patches with it to hold it there, however I will likely use even more of velcro around the cutouts than they provided.
Good luck on your project!
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01-23-2009, 05:07 AM
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I know the 3M spray won't hold...tried it on a peeling dash (no good) But a true vinyl adhsive will.
The vinyl patch for my test area with the kit vinyl adhesive worked great...it'll never come off.
However, the vinyl patch with vinyl adhesive didn't adhere well to the 3M 4000 and bubbled. I'm not sure if I didn't let the 3M 4000 cure long enough, or the two componds don't mix. I'll retest tomorrow after letting the dash bake in the sun for a day.
Given the scale of the damage, I may consider using one large sheet for the larger area rather than small strips to cover the 3M 4000 filler. It'll probably look better and last longer.
I'm sure it will crack again, but with one large sheet of new flexible vinyl, that may help absorb some of the impact and last longer...great idea!! I knew there was a reason I keep you all around ;-)
However, the vinyl patch with vinyl adhesive didn't adhere well to the 3M 4000 and bubbled. I'm not sure if I didn't let the 3M 4000 cure long enough, or the two componds don't mix. I'll retest tomorrow after letting the dash bake in the sun for a day.
Given the scale of the damage, I may consider using one large sheet for the larger area rather than small strips to cover the 3M 4000 filler. It'll probably look better and last longer.
I'm sure it will crack again, but with one large sheet of new flexible vinyl, that may help absorb some of the impact and last longer...great idea!! I knew there was a reason I keep you all around ;-)
01-23-2009, 05:13 AM
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good luck!
was planning on doing something similar to our UrQ until I found a mint dash in an '82 4000. Now we just need to preserve the new dash 
When looking into redoing ours, I was thinking of using a bondo-product to level the surface out and then recover w/ leather or vinyl. Thankfully I won't ever have to figure that one out now, though might play w/ the old dash just for $hits and grins.
When looking into redoing ours, I was thinking of using a bondo-product to level the surface out and then recover w/ leather or vinyl. Thankfully I won't ever have to figure that one out now, though might play w/ the old dash just for $hits and grins.