Complete Brake replacement and AC replacement repair job for 1970 280SL

[CromeYellow]

Also, do people typically restore the odometer to 0 after a complete engine rebuild and restoration?  I read about one 280SL that was recently sold around $100K where the odometer had been reset.

 As I recall the miles are 36000 or so right now.  The car wasn't driven at all for over ten years of its life, and very rarely before that.

I am sure the best is to leave the odometer alone, but just wondering.

[mauro12]

Have you guys ever tried for our car the Brembo brake pads ? I want to replace my discs and pads and I’m wondering which one is the best choice . Ate discs and pads or Brembo ? I read a lot of very good reviews about Zimmerman brake discs , they have a really high quality coating . Which is the best combination in your opinion ?

[johnk]

I wasn't planning on clear coating over the polished finish?  Should I?
https://www.youtube.com/watch?v=P-6_EpDh0jI
https://www.eastwood.com/exoarmour.html

I would was told not to clear mine after vapor blasting. Clear can yellow over time and vapor blasting creates a smooth non porous layer on top. I would guess that your finish should be smooth enough to keep clean. You would want to use clear coat if you just bead blasted your aluminum as that opens the pores rather than closing them.

[CromeYellow]

The car currently has Pirelli P4000 tires
205/70 R14

The tires have almost no miles on them but have been idle for a decade so I will replace them.

Should I stick with the same 205/70 R14 size?

[Benz Dr.]

The car currently has Pirelli P4000 tires
205/70 R14

The tires have almost no miles on them but have been idle for a decade so I will replace them.

Should I stick with the same 205/70 R14 size?

I wouldn't go any wider. Good chance of rubbing even with 205's.

[neelyrc]

Lots of discussion here on the forum about tires and tire sizes.  The search function is your friend.  My personal preference is for a size closer to original tires.

Whatever you decide on size, don’t drive an inch on those 10 plus year old ones.

[Cees Klumper]

I had those Pirellis and really liked them. After ten or so years swapped them for narrower Vredesteins, which look more correct, but I preferred the ride the Pirellis gave. Of course this is 20 years ago, so today the comparison could well be different. There was no rubbing with the 205 Pirellis.

[CromeYellow]

I did search a lot.  So between the Vredestein 205/70VR14 and any other 205/70 R14 would there be any difference in size though?  The Vredesteins are narrower than the same size Pirelli 4000?

Are the Vredesteins narrower than for example the, Michelin Defender 205/70 R14 ?  These are T speed rated though, while the Pirelli 4000s were H rated I believe.  The Vredesteins are V rated?  That would be more than fast enough!

What would be the next size smaller down from the 205/70 R14, versus the original 185/80 HR14 ?  195/75 R14?

[Cees Klumper]

The width is indicated by the first number: 205 means 205 mm wide (20.5 cm), 185 is 18.5 cm etc etc.  So 205 Vredesteins should be exactly the same width as Pirelli 205's.

The Vredesteins I got are the original width, the Pirellis were only available (when I bought them 20 years ago) in 205 so that's what I got then. Although 205 did not look out of place on my car, I do prefer the original width, or at least not more than 195, but that's personal preference, as is whether to go to 15 inch wheels over the original 14 inch.

[neelyrc]

What would be the next size smaller down from the 205/70 R14, versus the original 185/80 HR14 ?  195/75 R14?

 

I am using the 195/75 R14.  This  size is the closest to the original tire in diameter/circumference.

[CromeYellow]

The engine looks like the below pic now.  He has finished the brake work and installed the new AC parts under the engine but now needs to work on the area behind the dash as well as either finding or having fabricated the AC hoses.

Along the way he replaced some other parts too, not related to the brakes or AC, which he felt needed to be changed, which is what I like about what he does.  He doesn't just go in and fix one thing he addresses anything that looks like it should be replaced.  It is a restoration job in progress.

[MikeSimon]

Maybe somebody can help me out here. I keep looking at the pictures of - among other things - the polished parts posted on February 12 and for whatever reason, both the valve cover and the intake manifold do not look M130-983 to me...Why is is? Do I need new glasses...again??

[hansr433]

Yes I asked for and paid for the valve cover and manifold to be polished.  If I ever sell the car I doubt the buyer on that day is going to ask for them to be returned to beat up old looking condition.  It's a one owner car (my father and I) so I suppose I may say that I am entirely responsible for it in all respects.

Nothing rebuilt is going into the car.

I am sure that you know that the original finish on the valve cover and manifold was engineered to dissipate heat?  Polishing negates this.

[MikeSimon]

Well....if they were "engineered" to dissipate heat, they would be black!

[dirkbalter]

Maybe somebody can help me out here. I keep looking at the pictures of - among other things - the polished parts posted on February 12 and for whatever reason, both the valve cover and the intake manifold do not look M130-983 to me...Why is is? Do I need new glasses...again??

I agree, looks different?

[CromeYellow]

The parts are original to this car.  Maybe look different because polished.

The engine is original too, and its # is
130-983-XX-XXXXXX


Speaking from an engineering point of view, how would a part that is polished dissipate heat any differently from a part that was not polished?  Aren't we talking about internal heat, not a function of sunlight bouncing off the surface?

Just another little thing the mechanic did was after the new AC compressor came in he noticed that it was "Made in China."  It was identical to the one that had been in the car from Day One, but I guess some of these compressors are nowadays Made in China.  He returned it and got the original made in USA compressor for the car, which was harder to find new, but he got it.  He is being paid a flat rate by me and didn't get a penny more for seeking out and using the made in USA compressor.  He's done it like that countless times during this process.

[hansr433]

Well....if they were "engineered" to dissipate heat, they would be black!

Not necessarily.  I am referring to surface composition not colour.  The original pebble finish offers much more surface area than a polished finish, thus better heat dissipation.

[CromeYellow]

Interesting thought.

I did find some discussion on that concept
https://boards.straightdope.com/t/polished-engine-vs-heat-transfer-and-performance/728409
but the difference, if there is any difference, seems to apply to internal parts.  Again, I find it hard to swallow that the finish of an external part would affect the flow of heat going outwards, when it is not a moving part. 

If there is any difference as to an exterior part's finish of this small size I doubt it could be measured?

And if you dig deeper, there are those who claim that
"a polished surface will reflect radiant heat energy better (like a mirror) and absorb less. Likewise once hot , that surface will not emit as much heat due to the polished surface. A rough cast surface however will absorb more heat energy (less like a mirror) but will also be a better emitter of the energy. Like I said, once heat soaked, it comes out a wash so is relatively inconsequential what surface finish the UIM (upper intake manifold) has."

[Benz Dr.]

Interesting thought.

I did find some discussion on that concept
https://boards.straightdope.com/t/polished-engine-vs-heat-transfer-and-performance/728409
but the difference, if there is any difference, seems to apply to internal parts.  Again, I find it hard to swallow that the finish of an external part would affect the flow of heat going outwards, when it is not a moving part. 

If there is any difference as to an exterior part's finish I doubt it could be measured?

And if you dig deeper, there are those who claim that
"a polished surface will reflect radiant heat energy better (like a mirror) and absorb less. Likewise once hot , that surface will not emit as much heat due to the polished surface. A rough cast surface however will absorb more heat energy (less like a mirror) but will also be a better emitter of the energy. Like I said, once heat soaked, it comes out a wash so is relatively inconsequential what surface finish the UIM (upper intake manifold) has."

Maybe. Ever look at a tea kettle?

[CromeYellow]

Well here are the parts before polish / plating.  Not exactly sure there is any engineering difference as far as surface area.




I think the polishing and plating I did changed the cosmetics is all.  It is after all an exterior finish.

[MikeSimon]

Have you ever looked at air-cooled motorcycle engines? Those that used in racing or high performance have black cylinder heads and engine barrels.
I know it is hard to swallow for someone who has not been exposed to physics much, but black surfaces emit heat better than light color ones.
And of course, an increased surface helps also. That's why we have "cooling fins".
Engineers are usually concerned about performance. Marketing guys are concerned about looks. That's why we have polished parts.

[Benz Dr.]

It's your car and as such, you can do it any way you like but I can see all sorts of incorrect finishes all over your engine bay. We probably shouldn't get into any sort of a protracted discussion about any of this. 

[CromeYellow]

If it is ever sold, in another thirty or forty or fifty years or whatever, it will probably be the only one owner only, West Coast only, 280SL on the planet, with very very low original miles on it, so I doubt that buyer is going to pick any car over mine.  Or it might just remain in my family and never be sold.

As I looked across the internet I saw a variety of different ways people had done the different parts, in a half century I am sure there will be even more variations, and even more discussions as to what is "correct." 

In the meantime, exactly, it remains my car.

[Cees Klumper]

... and just maybe, today some parts made in China are better quality than the same part made in the USA, or Europe or other places for that matter.

[CromeYellow]

Well the point was to replace the part with a part that was made in the same place as the original.  Not just the same manufacturer and part, but made in the same place too.