Mercedes 560SL Performance Road Car

It’s symbolic of independence, the American elite, the partygoers, celebrities, and those with the budgets for tailor made suits to match. The 560SL was a reactionary plan, implemented by the chiefs at Mercedes-Benz in 1985 to ensure they kept their affluent American followers on side, with a little show of appreciation to the Japanese and Australians, too. This was in response to the grumbles of owners outside of Europe who, due to emissions regulations, had their engines restricted with various emerging technologies, such as catalytic converters that did not become a legal requirement in the UK until 1991.

About the R107 Mercedes 560SL

The 560SL features a naturally aspirated SOHC M117 V8 with Bosch KE-Jetronic Fuel Injection, producing 227 bhp @ 4750 rpm and with a redline limit of 6,000 RPM. The 560SL is one of the most powerful of the R107 variants, relying upon vented disc brakes at the front and solid at the back with the ABS function standard by this point in the production timeline. The engine setup delivered the power to the rear wheels, propelling the SL from 0-60mph in 7 seconds (as a new machine) and could complete the ¼ mile in 15.5 seconds.

Where the other Mercedes-Benz R107 variants were offered with few optional extras, the 560SL came with almost every optional extra offered by Stuttgart, bar heated seats and orthopaedic back rests. This meant that the 560SL was endowed with ABS, limited slip differential, driver’s side airbag, climate control, a foot operated parking brake, cruise control and much more.

Why might you ask are these details significant? The 560SL is not something we see regularly at SLSHOP, with only a few gracing our workshops on an annual basis. This article discusses our first 560SL SportLine build which features a vehicle shipped to us from abroad. As we have discussed, the 560SL makes a perfect contender for SportLine, due to its large displacement engine and uprated differential. Similarly, the standard creature comforts allow us to turn the 560SL into more of a sports car that meets modern demands.  

The Objective: 

To derestrict and make the 560SL more reliable and efficient for everyday use, increasing power marginally and improving the handling to give the 560SL a more modern feel in corners and upon acceleration.

The Details:

Efficiency and reliability:

Owners of the R107 model will know that the fuel injection systems are some of the most complex elements of these machines. The Bosch KE-Jetronic system found on the 560SL become tired and unreliable with time; they are simply not easy to replace. Our own purchasing department struggles to find replacement components, and the refurbished examples are not always up to standard nor able to maintain the correct tolerances.

We have therefore developed a new electronic injection system, removed the distributor and replaced with a modern coil pack, adding a programmable ECU for better ignition timing and fuel injection. A better and more precise spark is achieved and thus better engine operating conditions. Alongside this, we have fitted a new stainless steel exhaust system to allow the ECU to process emissions more efficiently, contributing more power and economy to the 560SL as a whole.

The stainless steel exhaust system is of our custom design, featuring a custom manifold and the deletion of the twin pipe from the centre box to the backbox. Instead, we have used a single pipe from the centre to the end, improving the flow of gases. A revised soundtrack is also achieved by using twin straight-cut rolled tips that give a more sporting vibe to the 560SL.

Power command:

Where the original rear axle ratios of 2:47 was taken from a 380SL, we’ve increased this to accommodate a double overdrive six-speed modern Mercedes-Benz manual gearbox. The new ratio is better suited to this box and improves the fuel consumption. Similarly, the manual transmission offers the driver better access to the M117’s power, allowing them to charge through the rev range at their own command.

720 Degrees of Handling:

As we pointed out in a recent article discussing the benefits of an anti-roll bar kit, the 560SL similarly required the same upgrades. Where a standard R107 requires a pre-flight checklist before approaching a corner fast, the addition of anti-roll and sway bars, as well as upgraded, lower suspension, gives you full confidence in your R107’s ability to corner like a modern car. Gone is the need to be reluctant, replaced by your ability to throw your SL into a hairpin without fear of dangerous body roll.

Where the power from the M117 wants to be unleashed, it requires the right setup to bring it to a halt. We’ve therefore added grooved discs and uprated pads at all four corners. These uprated brakes can be sourced directly from our leading parts website.

What do the Readings show?

This Mercedes 560SL is yet to go on the Dyno, with the readings expected to show an increase the Mercedes 560SL horsepower from the stock figure of 272bhp. We will update this article with progress on the project and a verdict on how it drives from the owner.

Inside this Mercedes 560SL

To further emphasise the uniqueness of this particular car, we’ve re-trimmed the Mercedes 560SL interior dashboard in a lovely combination of black leather with double red stitching. This adorns the top of the dasbhboard, integrating beautifully with the outside temperature gauge and vents. The steering wheel has also been re-trimmed in the same combination, offering the driver more of a tactile feel when hurling down straights ad into corners.

To summarise this build so far, this is what the owner has to say: ”You guys turned my peaceful American grandpa into a wild stallion!”

We’ll be updating this thread with progress on the build and a video on the overall outcome, showcasing the performance, handling and the sound offered by the custom exhaust system.