Mercedes 300SEL 6.3 Racing Project

Grant V

Member
Messages
242
Finally some progress!
I got the brake calliper mounting brackets back from Powerbrake with the holes now enlarged. They also supplied me with new high-tensile allan cap screws instead of the original OEM screws. Powerbrake told me that I would need 15mm spacers on the front hubs to ensure the rims didn’t touch the callipers, so I visited the local H&R agents and bought a set of spacers that are meant for a VW Golf 1. The centres needed to be slightly machined to fit to fit over the bearing dust caps, which was done by a friend of mine on his lathe at home and cost me a pack of beer
I had worried a bit about wheel bolts for the rims because of the length required. The need for spacers on the front discs solved this problem - I needed to change to a wheel stud and nut arrangement. The AMG car also has wheel bolts and studs, as can be seen in the picture below.

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You can compare the rims on the AMG car to rims of my car (see below vs above) and see how different the AMG rims are compared to my stepped up Pentas. The Pentas don’t look bad from a distance, but the devil is in the detail and I would love to find a set of these proper AMG rims

The wheel studs turned into the hubs easily enough with a 6mm allan key socket although they needed some power because of the Locktite type coating on the threads. The spacers fitted on easily and everything came together.

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Like on the AMG car, there are slots cut out of the bottom of the fenders as air intakes for the brake cooling. I thought the easiest solution would be to direct the air up the chassis legs and then make an outlet on the chassis leg inside the fender to which I would then attach an air duct.

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You can see the gap at the bottom of the chassis leg through which air can pass. I would have to make a scoop to direct the air up the chassis leg.

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I wrestled a bit with the ducting and my plan was to thread it through the front of the suspension to the back of the disc, but this wasn’t to be as there was just not enough space to do this. I then decided to route the ducting under the top of the fender to the back and then down to the disc.
I bought some 63mm flexible ducting from ATS Motorsport and then set about making the mounting brackets. I could probably have bought mounting brackets, but didn’t think this far, so I just made some by wrapping them around a length of 63mm steel tube.

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I started at the back of the disc and secured the ducting to the top wishbone with a cable tie, I then routed the air duct and secured it to the inside of the fender as I went along, all the time putting the wheel on, turning it from lock to lock to check clearance, and then taking it off again. A bit of a chore.

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I worked out where I wanted the air outlet on the chassis leg to be and made an outlet pipe out of cardboard to check the proportions and spacing. I then used the cardboard mock-up to make marks on a piece of 63mm steel tube and cut this into shape.

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I then marked its position on the chassis leg and then made the outlet hole by drilling holes and chiselling the centre out. The edges of the hole were cleaned up with a die grinder and then the outlet was welded into place.

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I then set about making a mounting bracket to secure the air duct onto the front hub. I removed the brake calliper and disc and the fashioned a bracket from 8mm round bar and a piece of 63mm tube, which fitted into the mounting holes of the original backing plate. The 6mm mounting nuts welded to the bracket serve as both a securing device and as a spacer to space to bracket as close to the disc as possible.

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Finally the cable tie was replaced with a bracket mounted to the top wish bone of the suspension and everything is now secure and in place with enough space not to touch the wheel in any position, nor to get in the way of the suspension moving up or down.

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2b1ask1

Special case
Messages
20,220
Brilliant dedicated work as ever, steady progress and here's hoping to see it finished soon!
 

Grant V

Member
Messages
242
Just an update on some of the work that I've completed since late last year.

I set about making the scoops to fit behind the cut-outs on the front valance to direct the air up the chassis legs. I made a mock-up from cardboard and when satisfied that it worked, I flattened it out and used it as a template. I outlined the shape of the template on a sheet of steel, cut it out and then bent it into shape

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I made another template and then cut out a piece of sheet, which was welded in place on the side of the chassis leg. This was to cover the gap between the radiator and the chassis leg.

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I fitted the scoop and then found that it half covered the holes drilled for the nuts and bolts that secure the fog light bracket to the front valance. I reckoned it would be easier to shape the scoop to accommodate the nuts and bolts than to make a new one.

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The gap at the bottom of the chassis leg needed to be covered as well, so I made another plate, and then tacked it into place.

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The left hand side was more tricky because of the space constraints. There was a mounting plate right behind the cut-out on the left valance which needed to be removed, but I couldn't get in there with grinder. I had to remove the fender to expose it, which was pretty straight forward. You can get a better idea of the brake ducting with the fender removed.

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I had no choice but to remove the air compressor and power steering pump assembly, fuel filter and alcohol jar to be able to get into the place where the air scoop had to be fitted. I then replicated everything that was done on the right hand side, but it was necessary to move the fuel filter somewhere else, as there wasn't enough space left once the air scoop was fitted.
I made a bracket and mounted the fuel filter in the boot. Some new fuel pipes were made that were longer and the system was plumbed in.

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This weekend I set about making the frame for the gauze, which covers the intake hole on the front valance. You can see from the period picture below that the original car merely had a gaping hole in the valance, but I thought it would look better if the hole were covered in gauze, which would also prevent stones or other debris getting into the intake system – not desirable.

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I made a template out of cardboard, which I traced onto a sheet of steel, and then cut out two profiles. The outside edges were shaped on a bench grinder, and then the insides were cut out with a nibbler, then a die grinder and file were used to finish the inside edges. The one frame was then placed inside the valance and formed into shape, which was then copied for the other frame.

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I welded two bolts into the valance to mount the frame, and then two bolts into one of the frames, which would secure the two frames together. Initially I thought I would just weld the frames together, but after some thought I realised that over time the gauze would have to be replaced, so I've made it in such a way that the two frames could come apart. Once all this was done, the frames were zinc plated.

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I bought a meter of stainless steel gauze used for fly screens from my regular hardware store, and cut out two sheets to fit the frame. The gauze was cut on the bias so that the mesh criss-crossed, and cut slightly bigger so that the edges could be wrapped over the edges. This done, it was bolted together and then fitted to the car.

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One and a half days work and you can't see the frame from the outside…..

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The car is now effectively ready for track testing, but I've been waiting for a set of Bilstein shocks to be made for the car since June last year. They're being made for the car by SA's foremost Bilstein guru, so I know that they'll be right. But still a frustrating wait.
 

Grant V

Member
Messages
242
The shocks were finally dropped off at my house a few weeks ago by Ted Garstang, South Africa's foremost shock and Bilstein specialist. Ted is in his early seventies and has been involved with Bilstein and racing for at least forty years – there's nothing anyone can tell him about shocks and suspension set-up.

I was absolutely thrilled with the result and they are beautifully made.

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The bottom mountings are rose-joints with almost no play and the machined components are a thing of beauty. They fitted perfectly.

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Ted built these shocks specifically for this car and they have variable damping adjustment. Ted helped me fit the shocks this morning and is very happy with the damping parameters that he had decided on.

There is a small adjusting knob on the top of the shock which is turned to either give soft or hard damping. It only takes one and a half turns to go from the softest setting to the hardest setting and the difference is absolutely notable when you push down on the car. He still has to supply me with the locking mechanism to keep the adjustment knob locked in the desired setting.

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The front air suspension was continually dropping within half an hour of switching off the car, so I set about finding the problem, which was eventually traced to a leaking air bellow. It was a new part, so this was most unusual.
With the air suspension working properly, I set about getting the ride height where I wanted the car to be, judging from photos that I had of the ‘Rote Sau'. Once this was done, I sent the car in for wheel alignment, which absolutely transformed the car. Before the wheel alignment, the car was all over the show and a real handful on the roads around my house

The next step was to put the car on the track for testing and see how it would handle in terms of cornering and braking, and then do the required changes to the damping to achieve the best result.
The general idea is to start with the same tyre pressure all round and the same damping front and rear. If the car understeers or oversteers, then we will change the damping at the front or the rear in small increments, with the car being driven after each individual change is made to see what affect the setting change has.

The big day finally arrived last Sunday when I put the 6.3 on the track for its first track test.

My best friend, Chris, on the right in the pic below, joined me and my other half for the test day. (Chris is an inspiration: he turns 72 in December and started historic racing two years ago. There are no excuses, chaps!)

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I was really nervous about this and expected the worst from the car. I expected it to be a handful with air suspension and basic street wheel alignment, as well as unknown damping settings.

What a surprise! After only about two laps of feeling the car out in terms of turning, braking and working out the gear pattern, I was able to start pushing it harder and the car was absolutely marvellous. I cannot explain how exhilarating it was. The car handles extremely well and it's tremendously forgiving. It turns in well and doesn't understeer, which is what I was expecting with that big cast iron lump up front.

Truth be told is that the car is not delivering the sort of horsepower that the chassis can handle. I have no doubt that a few horses have bolted in the last forty eight years, but the engine isn't revving freely enough over 4500rpm which is probably due to the fuel injection set up. It's been tampered with in the past, so I plan to get the car to a specialist to get the system overhauled and set up properly.

The car did start to get hot – just above the 100⁰C mark, so I will have to look at upgrading the radiator, even though it has been re-cored with a three row core. The electric fan works fine. There was also a lot of oil coming out of the power steering reservoir – I don't know if it was over filled or whether the oil is getting too hot and needs some sort of cooling system, maybe a re-routed pipe in front of the radiator? I'll start by bleeding the system again first.

I have to modify the brake pedal to sit closer to the accelerator pedal. The pedals are currently too wide apart and it's virtually impossible to heel-and-toe when changing down – it caused an interesting moment when I jumped on the brake pedal too hard when trying to heel and toe, unsettling the car and locking the rear brakes.

I had the 6.3 on the scale and it weighs in at a hefty 1548kg - she's certainly no light weight! I want to add lightness by replacing the front and rear screens with Lexan, but I will have to do some inventive stuff to get the weight down. The driver could probably start by getting some exercise and shedding 10kg….

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Here's a YouTube clip that was taken of the car on its first outing:

https://www.youtube.com/watch?v=pQ2yptWsFa0
 

zagatoes30

Member
Messages
20,759
Lovely work I just wonder how much air will get through that convoluted route to the disk, scoop, chassis rail and then pipe.

Proof of the pudding will be in the testing
 

Grant V

Member
Messages
242
Four weeks ago I put the car on the trailer and took it through to TW Diesel in Witbank, about an hour’s drive east of Pretoria, to get the fuel injection sorted out.

The business is owned by Rolf Frommjohann, a German guy who settled in South Africa many years ago via Namibia. One of the things I love about our car world is all the interesting people that you meet along the way, and Rolf is one of them.
He’s an auto electrician by trade, but was a research technician for Bosch during the development of the K-Jetronic system. The department was headed up by the engineer who invented the K-Jetronic system, there were five engineers working under him and each had his own research technician.
The fuel injection pumps for the Porsche 917 racers were sent to Bosch after every race to be set up for the next race considering the change in conditions and altitude. This was done in the workshop next to the research centre and Rolf had an arrangement with the technician there that when the Porsche pumps came in, he would be called to see how it was done.
During his time as a research technician, Rolf once spent a week with one of the engineers testing and analysing a Kugelfischer fuel injection system, which was strictly forbidden. After he had emigrated to Namibia, he read an article that Kugelfischer had got wind of these tests and Bosch was given a substantial fine by the authorities for having done this.
It’s encouraging that Rolf’s son is now working with his father, hopefully learning as much as he possible can.

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As I suspected, the fuel injection system on the 6.3 had been tampered with.
The thermostat on the pump was incorrect – it was from a W108 280SE – and the altitude compensator was knackered. Inside the pump one of the pistons was also misaligned and the steel pipes carrying coolant to the air sensor were totally blocked. The injectors are in very good condition and were probably replaced at some point. The injector mountings are perished and worn – Rolf pointed out that the mountings need to be 33mm, and most were about 31mm. Some of the ball sockets on the throttle linkages were also worn.
He gave me a quick lesson on how the pump works and I find the three dimensional cam absolutely mind boggling. I can understand how these cams can be designed and made in today’s world with computers, CAD and multi-plane CNC machines, but these things were worked out with slide rules and made by hand. Astonishing!

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I collected the car yesterday from TW Diesel and was absolutely gobsmacked at the superb workmanship. I assumed that Rolf would merely sort out the injection system, but I was absolutely stunned and very pleasantly surprised at all the extra detailing work that had been put in. If this is how the outside looks, then you can safely assume that what's been done on the inside is equally as good.
The coolant pipes that were rusted through had been repaired and plated, along with all the nuts, bolts and screws. The tappet covers and inlet manifolds were chemically cleaned and the oil filler cap had been polished with all hoses being renewed.
The difference in performance is marked, with the car turning over on a slow idle, but revving to the red like it has never done before. It's still in standard trim, but it's quick - very, very quick indeed and I can't wait to put the car back on the track again.
I'm absolutely thrilled with what Rolf has done - the care and attention to detail was totally unexpected.

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philw696

Member
Messages
25,114
Wonderful to read about and see the finished results.
You cant beat skilled workmanship.
Just Beautiful.
Thanks for sharing.
 

Grant V

Member
Messages
242
I made some good progress during the Christmas period tackling the endless list of things to do on the car.

The first thing I started with was the modification of the brake pedal. I needed to get it closer to the accelerator pedal to be able to heel-and-toe during braking and down shifting. There was no way I was going to take the pedal box out to tackle the modification, so I devised a ‘Heath Robinson' arrangement with a tie-down strap and some chain to get the pedal under tension. I then heated a small section of the pedal with an oxy-acetylene torch and tightened up the strap, which bent the pedal closer to the accelerator. It was a bit twisted, but with some more heat I was able to twist the pedal flat again with some vice grips. Once the car is stripped down for painting, I'll modify the pedal so that it looks straight again.
It feels good, but only a bit of track time will confirm this.

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The bonnet and boot lid straps have been lying in the bottom of my tool box for ages and they were finally fitted. For a bit of inspiration, I attached the fog lights and boot lid badges and the car now looks pretty much complete.

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At some point during the original car's life, holes were drilled into the left front valance presumably for additional air flow to cool the air compressor. In some other period photos taken at Spa, the holes were not yet there. The AMG replica doesn't have the holes either.

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I decided that the holes made sense, so I marked their positions and drilled them out, initially with a 6mm drill and then with a 10mm drill.

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Next I tackled the relocation of the battery to the boot. At the same time I fitted the centre console that I made during a sheet metal course I attended a year ago. It still has to be welded properly and finished off, but I needed to fit it so that I could install the battery cut-out switch, which is a mandatory regulation. I will also fit an engine start button and some other switches, like window washer and a manual override for the engine fan. I used almost 10m of battery cable from the starter via the battery cut-out switch to the battery in the boot, which weighs 6.5kg. I think I have overdone it with the cable – it's too heavy, so I'll speak to my auto electrician friend and see what the smallest core is that I can use to start the car and still save weight.

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The new battery is the smallest I can practically use, which is half the size of a normal battery for a 6.3. Adding lightness has become a bit of an obsession and losing the original battery tray and mounting brackets has saved almost 1kg.

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Removing the sound damping material on the firewall inside the bonnet, as well as the damping and steel plate inside the passenger foot well has saved 3.5kg.
The door checks don't look or feel too heavy, but incredibly, weigh a total of 1.9kg – that's almost half a kilogram each.

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I made new straps from nylon to keep the doors from opening too wide and damaging the bodywork. They only weigh a total of 64g.

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I never removed the aircon jockey pulley from the engine until now – that weighs 1.2kg. It all adds up and I'd like to find 100kg somewhere, but I think I might be optimistic.

I had a very interesting conversation with fellow competitor who is obsessed about adding lightness. He has managed to bring the weight of his series 105 Alfa Guilia down to 850kg. He said that there is eventually nothing more that you can remove to save weight and then you will have to start spending money to save weight, like replacing standard cast iron brake callipers with aluminium units, or buying fancy hollow camshafts instead of standard solid units.

It got me thinking about non-obvious ways to save weight and some things have come to mind. The original radiator and oil cooler are really heavy – maybe I could get aluminium units made that look like the originals. It would be easy to change them to modern aluminium units that are already available, but I want them to look original if I do make the change. The exhaust could probably be made of thinner gauge round tube and this would be a significant saving. Changing the front and rear windscreens, as well as the side windows to polycarbonate is already on the cards.
 

conaero

Forum Owner
Messages
34,593
My word, a man with lots of time on his hand to play with cars....very jealous. Keep up the good work!