Saturday, June 2, 2018

Mercedes 300 SLR: Planning

As a way of further avoiding dealing with the Auto Union, and as followup to the successful 190 SL and 300 SL builds, I decided to tackle the 300 SLR.


First off, the kit I obtained was a gift set, which also includes a kit of the newer Mercedes SLS AMG and some paint and glue. The box is enormous, and the bits had been thrashing about in there for some time, so there was some damage to more delicate components -- in particular, one of the rear hubs, molded in one piece with the chassis floor, had snapped off. However, it was cheaper on eBay than kits of the 300 SLR alone, with the extra kit of the SLS as a bonus, so worth it. (I have also ordered a similar kit of the BMW 507 and i8, also cheaper than a kit of just the 507, which is what I really wanted).

Second, the SLR may appear to differ only slightly from the SL, but make no mistake: this is a completely different car. The GP-derived straight 8, with two cams and desmodromic actuation of the valves, is leaned way over on its right side, where the sedan-derived six in the SL is leaned over to the driver's side.

The driveshaft runs under the driver's seat to the rear-mounted transmission, and forces the driver to straddle the clutch casing. The final drive is a swing axle with inboard drum brakes; there are also inboard drum brakes at the front, necessitating front driveshafts even in the absence of FWD. What a complex beast, with a mix of state-of-the-art and just plain old-fashioned choices that required lots of fine-tuning to get it right. Mercedes kept building swing axles until the demise of the so-called W108 series in 1972, and while they were a special low-pivot design intended to minimise the usual problems with a swing axle, it highlights how the company could be traditional in many ways.

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