BE 646

[Gus Meyjes]

Peter,
   
   I have not been on the forum for a long time. Your work is fantastic! Amazing progress and quality!

[dkp_cobra]

Back from the holidays I got a reproduction of my identification plate (above)
   
   
   
   I think it is a really good quality. So, I someone need also a new plate I guess the guy who made this one is happy to produce further plates.

[dkp_cobra]

Since my last update I worked a little bit on the footbox
   
   
   
   and was thinking about the strength enforcement of the chassis. I used a self-adjusting cross-line laser at the end of the car
   
   
   
   to get a horizontal line. I measured the distance of both main tubes every 10 cm to this laser line.
   
   It shows that even in the unloaded form the main tubes have the form of a banana
   
   
   
   The bend is nearly 9 mm at the widest distance.
   
   Then, I install the engine and transmission and measured the bend compared to the unloaded version
   
   
   
   Maximal 1 mm was added to the bend. To simulate passengers I add additional 205 kg in that area
   
   
   
   Maximal 2 mm was added campared to the unloaded version.
   
   
   
   The next measure shows the difference between this full-loaded and the previous half-loaded version
   
   
   
   As expected 1 mm maximal deflection.
   
   I made this static stress test over two weeks. The next pictures shows the difference in the full-loaded version between the first and the last day of measurement
   
   
   
   Also, as expected the frame bends a little bit more over the time. One important question is whether the frame flips back to it's original bend after un-loading. The next picture shows the difference between the original bend at the beginning and at the end of measurement.
   
   
   
   We can see the curves are nearly identical. The effect that the frame is more straight at the end is due to some reading errors during measuring.
   
   So, what I can learn from this? I think the frame is relatively strong for this kind of static stress. To enforce it by inserting some kind of metal web the main tubes must first be straightened. Is this possible? Will be the effect that the doors will not close anymore as Luke mentioned above?
   
   Any comments are very welcome.

[dkp_cobra]

Opening the main tubes:
   

   

   
   I had also opening the front part:
   

   
   What a lot of rust coming out of these small tubes going to the nose. I think the fault was not to drill a small drain hole into them where they hit the main tube.
   

   
   The left main tube was modified in previous times to allow a bigger gearbox:
   

   
   I opened this section to close it later when sleeving is done.
   

   
   Inside the tube it looks quite promising.
   

[dkp_cobra]

Today was the great day: sleeving the main tube! Everybody how did this before tells you the right preparation i.e. cleaning the tubes from inside is the key to success. How right they are.
   
   I used an axial grinder with a steel brush to clean the tubes from rust and the swarfs from drilling.
   

   
   I tested the clearance with a piece of the same diameter (70 mm) like the tubes which will be inserted.
   

   
   Now, the tube is really clean from inside. It was no problem to shift the test cylinder through the main tube.
   

   
   The only reason why the sleeving could be a hard work if the tubes are so clean is that the main tube is not straight but the inserted tube is.
   
   I used some kind of frame made from a steel girder in order to straighten the main tube during sleeving.
   

   

   
   Lubricating the main tube from inside:
   

   
   Now, it's show time. Will it works?
   

   
   I can see the head ...
   

   
   With all the preparation sleeving was indeed an easy job. It took 15 minutes and I used only a 3kg sledge. That's not much.
   
   Between the tubes is still a lot of grease which is quite good.
   

   
   In the front section the main tube is bent up due to the welding heat.
   

   
   A look from the back shows the old tube someone else inserted to enforce the back in the area of the differential mounts and the new tube.
   

   
   The tube I insered has a 70 mm o.d. and a wall strength of 1.9 mm. The weight is 6650g for one tube.

[Klassik Metall]

Well done Peter, as you rightly pointed out the trick to this job is in the preparation.
   Just remember to firmly brace the tube before welding in the repair section to stop it
   pulling/distorting.
   
   Regards,
   Luke.

[dkp_cobra]

The tube can be closed again:
   
   
   
   The cover plate has a hole for later inspection anticorrosive coating:
   
   
   
   The news sub-structure is connected with the old by sleeves.
   
   
   

   
   Now, the other side of the sub-structure can be removed and the tube can be opened.
   

   
   How the inside of the tube looks before cleaning
   

[dkp_cobra]

You could see that the right tube had much more rust inside. Another problem was that due to some dents on the bottom the i.d. was not always at least 70 mm:
   
   
   
   It took 5 (!!!) hours to clean the tube inside. At the end only the first 80 cm were rusty the rest was free of rust. I used rust converter in this section:
   
   
   
   
   
   Now, let the funny games start. Last time I thought I had the hottest day of the year to sleeve the left main tube. That was wrong. Today was even hotter and much higher air humidity. What a fun.
   
   
   
   But due to the intensely cleaning job the sleeving took again only 9 minutes.
   
   
   
   Grease squeezed out of the first welding hole.
   
   
   
   A look inside the new sleeved tube:
   
   
   
   Now, after cutting the overlapped tube the sub-structure can be restored. This will be the next job.
   
   

[dkp_cobra]

Closing the tube and restoring the right sub-structure. The main tube of the sub-structure was already sleeved in the past. I could/had to reuse it.
   
   
   
   

[dkp_cobra]

After holidays I closed the main tube
   
   
   
   and made a new engine mount. I think ít is version 3.1. The last version worked fine but I had the idea that the cross-bar can be used to reduce some misalignment of the main tubes.
   
   All I had to do was to extend the cross-bar by 2 to 3 mm.
   
   
   
   Well, I didn't extend the old cross-bar but weld in a new one.
   
   
   
   Now, it is finished and I can start with other tasks.
   
   
   
   
   
   

[dkp_cobra]

I have the impression that I have more than 100 holes in the frame which must be closed. Here are some of them
   
   
   
   
   
   Welding this section is not so easy. 5A too much and instead of closing a 2 mm hole you stare into a 10 mm hole.
   
   Now, they are closed
   
   
   
   I think that this open end was always a way that dirt, mud and water could have found its way into this sub-frame section
   
   
   
   Now, it's over
   
   

[dkp_cobra]

before removing the right sill
   
   
   
   
   
   and after
   
   
   
   
   
   the wood looks surprisingly good
   
   

[dkp_cobra]

You can see the right rear cross bar between the main tube to the sill tube. This was badly repaired some time ago.
   
   
   
   Today, I removed the repair panel. Oh, this doesn't look good [B)]
   
   

[dkp_cobra]

I think some of the Aceca owners know the problem with the upper cross tube over the differential. It's an important tube due to the upper mounting points of the rear shocks. In my car this tube was badly repaired in the past ...
   
   
   
   has holes on the one side ...
   
   
   
   and cracks on the other side ...
   
   
   
   This tube must be replaced. After cutting this tube another dropped down:
   
   
   
   because it has a little bit rust inside
   
   
   
   The upper cross tube behind the seats has a dent caused by an accident in the past.
   
   
   
   Time to try a new tool: a 3 kg panel puller
   
   
   
   This is no work for the fainthearted. As my welder says: the stroke you cannot hear hurts [xx(]
   
   But it works
   
   

[Migge]

Is it not better to remove the shell and sandblast the whole frame/chassis to see what's left?