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Mercedes 500K-AK Cabriolet (Pocher)


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Good Evening Gentlemen,

Here is the start of my Pocher Mercedes 500K Cabriolet build.

I have been working on this now for around 6 weeks, test fitting and painting parts for the massive straight 8 engine.

Below are a couple of photos showing the work I have done so far, there is still a very long way to go with this and many of the parts you see here are still only temporarily situated ( the coupling next to the starter is one of them,)

IMG_5053.jpg

IMG_5054.jpg

More updates as work progress'

Best Regards

Keith.

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Nice start, it looks great; I don't know what you were worried about. One tip, I found out when doing my engines was to get everything that needs to go next to the engine installed and work your way out so you don't have to pull stuff back off. I had to pull off the oil filler tube until I was done with the copper line as it kept getting in the way as did the supercharger linkage on the distributor side. I also had to put it all together just to get an idea of how was all going to look. I like the weathering and shading around the fuel pump it gives it depth good color choices.

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Beautiful work Keith. Very happy to see another big classic well done. Plenty of help here now; we'll all be watching.

Thanks very much Codger, I'm sure I'll have lots of questions.

Best Regards

Keith

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Nice start, it looks great; I don't know what you were worried about. One tip, I found out when doing my engines was to get everything that needs to go next to the engine installed and work your way out so you don't have to pull stuff back off. I had to pull off the oil filler tube until I was done with the copper line as it kept getting in the way as did the supercharger linkage on the distributor side. I also had to put it all together just to get an idea of how was all going to look. I like the weathering and shading around the fuel pump it gives it depth good color choices.

Wayne, thanks very much, I'm glad you like the colouring, I thought I would go with a grey/green sump and transmission to add another colour into the build.

The engine parts have been on and off so many times already, I thought once more for a couple of photos wouldn't hurt. I have now begun the final assembly of stage one of the engine build according to the Koo DVD and am well on the way with the engine2 section. So hopefully more progress will be made soon.

Do you think it is worth building the transmission next or the chassis? What are your thoughts on this?

Best Regards

Keith.

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I can tell you Keith on the Rolls it is preferable to build the engine and trans into a unit, apply finishes, then begin the chassis. Of course, being a contrarian, I built the chassis first (mostly) then the engine / trans. The idea is to be able to install them as a unit for squaring and alignment purposes.

Of course I bow to Wayne's superior Benz experience....

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You're welcome. I personally built the chassis next because the Trans doesn't come into play until much later on. The crossmember with the hole in it needs to be painted along with the rest of the frame but doesn't get installed until the firewall, engine and almost everything else is done then the Trans and crossmember go in together and the engine and transmission are supposed to be glued together. Having said that I still haven't glued anything together until I'm absolutely sure it's not coming back out.

What color green and gray did you use?

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You're welcome. I personally built the chassis next because the Trans doesn't come into play until much later on. The crossmember with the hole in it needs to be painted along with the rest of the frame but doesn't get installed until the firewall, engine and almost everything else is done then the Trans and crossmember go in together and the engine and transmission are supposed to be glued together. Having said that I still haven't glued anything together until I'm absolutely sure it's not coming back out.

What color green and gray did you use?

Building the chassis next does make sense to me too and this was my plan of attack.

The Gray green I used was Tamiya XF76 as this was a Matt finish I cut it with some X2 gloss white to give a satin finish and lighten it a bit.

I can tell you Keith on the Rolls it is preferable to build the engine and trans into a unit, apply finishes, then begin the chassis. Of course, being a contrarian, I built the chassis first (mostly) then the engine / trans. The idea is to be able to install them as a unit for squaring and alignment purposes.

Of course I bow to Wayne's superior Benz experience....

Thanks Codger, I'm going with the chassis next I think.

Best regards

Keith.

Edited by Mpfiend
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Codger, the engine and trans go in differently on the Merc than on the Rolls. I went back and checked and saw that your Roller unit is a engine/trans combo where the Merc the cross member that mounts between the engine and trans has to go in after the engine and before the transmission; I know that's clear as mud.

The sequence is: copper lines on the engine with it out of the frame, brake m/cyl copper lines get run then I bolted the engine in place and then installed the firewall and finished as much of the copper line that needed to be done between the engine and firewall and then the cross member goes in the frame and is not completely tightened down so it can pivot on the bolts and swing down over the bell housing ridge on the back of the engine and then the trans mates up to the engine. I also waited and did the steering column and the steering gear until after the copper lines were in because the frame kept getting turned over and steering column kept having the weight of it all on the the thin brass rod that the steering wheel screws down on. Lots of on and off on these builds.

Like I said before you have to build this in layers and try and see what is going to be in the way and get the stuff that will be covered up first. Believe me I had this thing apart and back together more times than I care to remember. So, you get the benefit of learning from my mistakes. Oh, and make sure you have painted and detailed the firewall before you install it otherwise it's a pain to do later; I wound up having to take it out and redo a bunch of stuff. Not enough hands and the ones I have are too big to do the work, go figure.

Wayne

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I bow to your Benz expertise my friend. And if I ever build one (if I ever finish THIS one...), I will buzz you for this well thought-out sequence. I think there's great merit in your 'build in pairs' method; improvements quickly come on-stream and the second takes less time to build. Lots of satisfaction in problem-solving.

Like 2 car race teams sharing data...

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I never really thought about it like that but, it does make sense when compared to a race car team. Puts me in the mind of F-1 teams testing their cars. But, you are correct the second one when built next to the first one goes together exponentially faster. Once you figure it out the second one is just a repeat of the first and there isn't much extra thought required.

Sorry Keith we're really not trying to hijack your thread so, I'll just shut up now.

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No problem Gents, chat away.

I have a question, probably the first of many.

I have had a look at the metal chassis and plastic cross members today.

After reading the pages relating to this on Paul's DVD, it says to adjust the chassis so that the cross member mounting holes line up with out stress to the plastic parts, but it does not give any measurements or reference points to work too.

At this early stage how can I tell if I have everything in the correct place and that the chassis is true and square after I have adjusted it for the fit of the cross members?

Best Regards

Keith.

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I would first measure the frame side rails for length and at each station where a crossmember fits. Then measure the spring perches from a fixed point. Sometimes the avles are mislocated because the locating points differ from side to side.

Then, same with the crossmembers; make sure they are the same widths and lay flat on a surface. Check that the 'X' has equal legs - this is Pocher we're talking about. Sand / file / drill / shim to get all right.

If all well, I'd assemble the chassis with fasteners to a flat surface to check for warp. Also would string diagonally from front to rear for an even measurement.

Failing all of that, buy one of Wayne's new chassis jigs!!

Edited by Codger
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The main thing with the plastic frame cross members is just getting the screw holes lined up with the metal frame. You can check the metal frame for square as Codger suggests before adding anything to it and once you have determined the the distances from corner to corner diagonally are the same you just need to sand or remove excess material for proper fit of the plastic cross members to the metal. The most important thing to do on the frame is back on the engine assembly section 2 on engine mount picture 2 and 3; note the two sanded down engine mounting tabs. Those need to sanded flat like the picture shows for the engine to fit later on. Also, glue the bolt in place on the front right side of the engine in order to save yourself a lot of headaches later. The bolt and nut go on the left side pretty easy but, there isn't any room to hold the bolt when installing the engine on the right side. You have to thin down the cross member because the bolts aren't long enough to start the nut otherwise. As I recall the frame was pretty straight and didn't require any adjustment work on mine other than the side body mounting tabs that you have to bend up after the plastic frame side pieces are installed.

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Thank you Gents for the information.

I have checked the frame for square by measuring diagonally corner to corner and this is ok, the query I have is with the back end where the fuel tank sits. this area is not flat, it has a very slight curve to it where the rear cross members are fitted. When the frame is up the right way, the centre of this section is higher than the two ends. Do you know if this is correct, or should it be flat straight across?

Best Regards

Keith

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Can you post a picture of the area you are concerned about so I can see exactly what you are referring to? In the meantime I'll take a look at mine since today I'm going to be taking the body off and doing some primer and the frame will be exposed.

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Can you post a picture of the area you are concerned about so I can see exactly what you are referring to? In the meantime I'll take a look at mine since today I'm going to be taking the body off and doing some primer and the frame will be exposed.

Thanks Wayne I'll get a picture up soon of the problems area, I have had another look at it this evening and it looks like cross member 74765-16 is slightly too long and is throwing everything out of alignment.

Best Regards

Keith.

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You will find that as you go on with the build that there are a lot of things with the Pocher kits that have problems and some of them are BIG problems that will need to be corrected as you go. I am attaching a picture of the cylinder head of one of my Alfa Monzas to illustrate the point. Don't be afraid to adjust things to fit; you will find that you will be doing that a lot. The assumption is that the Pochers being so expensive are automatically good and perfect kits and nothing is further from the truth. They are expensive, no doubt, but as most of us that have built a Pocher will tell you, they are more of a starting point or a platform to build a museum quality model. I wouldn't say that an OOB build of any of the Pocher kits is museum quality. If people are looking for the fit and finish of a Tamiya kit you won't find it here. Ok, having said all that here are 4 pictures that illustrate my point about fit and finish of the Pocher parts.

Here is the fit out of the box of the head on the engine block. Totally warped at both ends the head is actually twisted.

IMG_2724_zpsrbf32jvp.jpg

IMG_2725_zpskccxu6ke.jpg

A lot of this

IMG_2721_zpssfvcbhl3.jpg

Gives you this

IMG_2728_zpswmfmppjq.jpg

That was a lot of sanding and material removed. I will need to mock up the manifolds etc to see if I need to shim under the head to get the proper clearances. The point being, don't be afraid to make changes and fix problems; after all it's only plastic and you can fix it.

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Good afternoon Gents,

Wayne thanks for the info on the chassis and the general fit of everything. I did come across similar challenges whilst building the engine parts.

I have now made progress with the chassis parts and have eliminated the problem that I had with the rear end. this was achieved by shortening the cross members by 1mm.

I have now test fitted all the chassis components, so I can now remove them all again and fix the sink marks and mould lines before painting.

IMG_5056.jpg

IMG_5062.jpg

IMG_5060.jpg

I have built up and painted the Air cleaner and test fitted it to the top of the engine, I have also test fitted the rocker cover. the air cleaner still needs polishing and clear coat now that I know it fits in place ok.

IMG_5068.jpg

I have also done a little more on the engine by adding some of the copper lines, these need removing again now as I want to add some brass nuts to simulate the ferrules at each end.

IMG_5067.jpg

I will add the HT wiring once I have test fitted the engine and gearbox to the chassis to try and minimise handling and breakages

More soon,

Best Regards

Keith.

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Looks like you're moving right along it's looking good. I ran into a problem with mine on the air cleaner interfering with the horn on the firewall and I still haven't gone back and fixed it; I think it's the brackets somehow got tweaked. I don't recall if it's on Paul's DVD or not but you should reinforce the fan bracket otherwise when the belt goes on it will pull the whole thing down. Instead of using the regular bolt to hold the pulley on the bracket you use a piece of threaded rod and run it all the way into the head and that keeps the pulley and bracket from pulling forward with the belt tension. Good work Keith keep it up!

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Thanks very much Codger,

I bought the jack stands when i built my pocher Aventador earlier this year. they came from eBay.


ATB

Keith

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Thanks very much Wayne,

I have seen the Fan mod but I'm planning to make my own fan belt so as not to add too much load to the bracket I have also made a different pulley for the generator assembly as the original wasn't moulded particularly well.

I should have some more done soon

Best Regards

Keith

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Wayne, I have another question with regards to the engine bearer 74578-20-N.

How much did you have to remove from the engine mounting points on part 74578-20-N? can you give me a thickness dimension of the two pads that the engine sits on please?

Best Regards

Keith.

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I can't really get a micrometer on it now with the engine in place and the body on it but, I think I sanded down about 40%-50% of it so it was fairly flat but still had enough to support the engine. I hope that helps.

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