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What did you guys do about dry rot on the black bumper trim?
"Back To Black" seems to work pretty good on restoring black trim. Did a nice job on the rub strips and black plastic door handles of my Jeep Cherokee.
The strip on the front bumper is not rubber, it is painted. The front bumper is plastic, but the strip is painted satin black. The solution is to repaint it.
Bumpers and trim on my all original 85 5letter love Back to Black. Paint is not a good alternative. It is a “rubber like” compound. It has a softer durometer texture. Back to Black is “sucked up” and really lasts a long time in so far as retaining sheen.
2nd Place DGRR 2017
The strips on the front and rear bumpers are painted on though.
the strips along the sides of the car are rubber or black plastic but the bumpers are paint.
i guess I’m going to have to research this a little further. This is my third 7. Having totaled two in the 80’s I would have noticed a painted surface vs a molded compound surface. If they were “painted” I think I’d have noticed the surface compromised. the bumpers are a molded process possessed of two seemingly different polymers as is such the case with co-extruded or dual-durometer extrusions (I.e flexible and rigid). Also, having owned a plastic extrusion company for a number of years I do have some knowledge of such things. The durometer of the “raised” or “rubber” portion of the bumpers is a different durometer. My finger nail tells me so. And, the Back to Black will not penetrate a hard surface. It is obvious that the top front and bottom front are painted the color of the rest of the car. Back to Black does however penetrate the raised area of the bumpers. It does not the other two. I have seen many individuals paint the raised strip of their bumpers. Perhaps yours is one of theirs. I have also noticed that the painted ones I’ve seen do not show proper adherence to the surface furthering my opinion that it’s not a higher density monomer, polymer/co-polymer. One thing is for sure.. Back to Black works well on those bumpers and lasts a long time, even if you neglected them. The more time you let it soak in the better the results. My 2cents
"British first" Der beste Heckspoiler der Welt, der aus Großbritannien kommt. Übrigens bin ich nicht britisch !!!
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Thomas,the color and finish of the paint on your car is extraordinary! I think this everytime i see a pic of it. Can you give details on paint products used on your car. Likely only available in your region,am curious. I favor PPG product here in USA.
i guess I’m going to have to research this a little further. This is my third 7. Having totaled two in the 80’s I would have noticed a painted surface vs a molded compound surface. If they were “painted” I think I’d have noticed the surface compromised. the bumpers are a molded process possessed of two seemingly different polymers as is such the case with co-extruded or dual-durometer extrusions (I.e flexible and rigid). Also, having owned a plastic extrusion company for a number of years I do have some knowledge of such things. The durometer of the “raised” or “rubber” portion of the bumpers is a different durometer. My finger nail tells me so. And, the Back to Black will not penetrate a hard surface. It is obvious that the top front and bottom front are painted the color of the rest of the car. Back to Black does however penetrate the raised area of the bumpers. It does not the other two. I have seen many individuals paint the raised strip of their bumpers. Perhaps yours is one of theirs. I have also noticed that the painted ones I’ve seen do not show proper adherence to the surface furthering my opinion that it’s not a higher density monomer, polymer/co-polymer. One thing is for sure.. Back to Black works well on those bumpers and lasts a long time, even if you neglected them. The more time you let it soak in the better the results. My 2cents
Would like to weigh in here,having owned several not cosmetically perfect 1st gens,i can speak to the painted surface on front/back bumpers. If ever the blacked out portion of bumper is scratched/gouged away,you can see body color underneath. The complete used bumper i bought a while back to repair accident damage to my SE shows this. It is original paint and is apparent someone dragged this bumper along a rough surface that has rubbed some of surface away and color shows thru those areas.
Regarding the paint adherence issue you refer to,very likely the cars you see with these problems and not just Mazda/RX related,are suffering from poor prep and lack of flex agent used in paint process which affects outcome/durability of finished product.
I do agree on Back to Black for being best product to rejuvenate these areas and seems to last longest.
i guess I’m going to have to research this a little further. This is my third 7. Having totaled two in the 80’s I would have noticed a painted surface vs a molded compound surface. If they were “painted” I think I’d have noticed the surface compromised. the bumpers are a molded process possessed of two seemingly different polymers as is such the case with co-extruded or dual-durometer extrusions (I.e flexible and rigid). Also, having owned a plastic extrusion company for a number of years I do have some knowledge of such things. The durometer of the “raised” or “rubber” portion of the bumpers is a different durometer. My finger nail tells me so. And, the Back to Black will not penetrate a hard surface. It is obvious that the top front and bottom front are painted the color of the rest of the car. Back to Black does however penetrate the raised area of the bumpers. It does not the other two. I have seen many individuals paint the raised strip of their bumpers. Perhaps yours is one of theirs. I have also noticed that the painted ones I’ve seen do not show proper adherence to the surface furthering my opinion that it’s not a higher density monomer, polymer/co-polymer. One thing is for sure.. Back to Black works well on those bumpers and lasts a long time, even if you neglected them. The more time you let it soak in the better the results. My 2cents
Ok perhaps the American FBs had rubber bumpers then, everywhere else its definitely paint.
I stand corrected.. when I wrecked mine in the late 80’s it badly scratched and gouged the bumper. It didn’t show another color below (84 GSL). That one was gray (tornado silver I think) and the painted portion was black underneath. The raised portion was the same color underneath as the top.. as I recall. Being much newer back then it gave me the impression that it was not the same as the painted portion. But!!! Back to Black made my “rubber” bumpers look new again on my current 5 letter.
Every RX7 I've seen, including my own has had a painted strip on the front bumper, but this post has caused me to reconsider whether they may have just been due to prior accident repairs, touch-ups etc.
Urethane parts would have come from the plastic supplier in natural black colour, just like all modern PP plastic panels do now. When assembling the car, it is entirely possible that Mazda only painted the top and bottom sections and left the strip in its natural urethane colour so that it looked like a continuation of the rubber body moulding.
Looking into it further, there is some evidence for that. If you buy a genuine replacement bumper skin from Mazda (yes they are still available), they come in grey primer, except the centre strip is taped over, which may be because it is black underneath, as shown below:
Based on this, I have reconsidered my previous views and the jury is out for me on what was "original" when these cars left the showroom, but certainly most people nowadays will likely find the black strips on their front and rear bumpers are painted on. These doesn't necessarily change the advice on how to make them nicer, as all the blacking products tend to made satin black painted parts look nice too.
This is really inconsequential but I must admit there are possible scenarios. I went out and polished the front end on mine..(summer is getting closer.. bugs are coming back big time) today and looked real close at the bumper. It’s obvious that the upper and lower are masked and painted metal flake black (sparkling black metallic). When I looked real close (34 years old ya know) it’s just not acceptable that my raised portion was treated the same as the rest (painted upper/lower). Just my 48 years of working with plastics that makes me say this. Short of ruining my own bumpers I’m fairly convinced that the material is more like urethane, as mentioned, and conceivable that Mazda high buffed the upper and lower to ultra smooth to accept the paint to closely match the metal. They did a great job IMO. Years ago those raised areas turned gray, almost white-ish as did the side moldings. Both acted the same and we know the side moldings are a dense “rubber like compound” possibly high density urethane. It took many thick soaking applications of B to B to get them new again. I tried a lot of other products short of oil itself. Whatever is in B to Black is obviously a restorative recipe. Great stuff.
My idea of a Sunday drive. Sadly, it doesn't happen often enough.
First time at Circuit of the Americas, much bigger than the little club track I'm used to.
I recently got my '79 Limited back from the auto body shop. They repainted the windshield metal trim moldings (matched original color) and installed a reproduction pinstripe kit. Everything
turned out great! Here are some shots.
Last edited by GaryInSeattle; Apr 10, 2019 at 11:18 AM.
My idea of a Sunday drive. Sadly, it doesn't happen often enough.
First time at Circuit of the Americas, much bigger than the little club track I'm used to.
I bet it was a hoot through the esses! Then just hold your arm out the window on the back straight; the plight of the low HP driver. I know the feeling well.
I bet it was a hoot through the esses! Then just hold your arm out the window on the back straight; the plight of the low HP driver. I know the feeling well.
Pretty much how it went. Lots of people in the beginner group had high hp cars. I can't wait until next time, hopefully with tires better than all-seasons.
