This article about suggested enhancements for your Mercedes W113 Pagoda SL originally appeared in the September / October 2015 Issue of the printed “SL Market Letter”. Guest columnist and long time Mercedes-Benz aficionado, Alex Dearborn, put his many years of Pagoda SL ownership to good use and penned this piece addressing some of the more common enhancements to be carried out on 230SL – 250SL – 280SL series cars for maximum enjoyment, comfort and reliability. With a bent on retaining the integrity and original nature of the car, this is a solid list that anyone looking to get the most out of their Pagoda SL should consider.
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Enhancing the Pagoda SL
Now that the 230SL, 250SL and 280SL (W113) cars have aged into collectable status, its easy to forget they are probably the most comfortable and usable open two-seaters of their era. Since you read SLML, there’s no need to extol the obvious virtues of these durable and surprisingly modern cars. But lets examine the differences between these SLs and their 2015 counterparts. Lets say you have a MB SLK or BMW Z4 in the garage along with your “Pagoda” SL. You’re going off for the weekend. You don’t choose the SL. Why? Well, you say, the old SL has great seats, decent handling, plenty of speed, large trunk, and its dependable….. and yet: it’s noisy and seems to be working too hard at highway speeds. The AC isn’t as good as the new cars, the soft top is hard to put up (where’s the push button?) and the car has the disconcerting habit of nose-diving under hard braking.
OK, so if we fix all that: would you then choose the SL for your trip?
Noisy engine: The W113s are geared too short for today’s highway speeds. All Pagodas rev at 3500+rpm at 60MPH, so by 80MPH it’s a real racket. A few cars came from the factory with the ZF 5-speed gearbox, featuring an overdrive 5th. ZF (the original supplier) is remaking these units but for over $10,000 + installing. The “taller” rear axle assembly from a 280SE 4.5 sedan will swap in, for 1/4th the cost and a clear improvement in quiet at speed. Same benefit to automatic or 4-speed manual transmissions. You’ve probably noticed that in W113s (all engines) 1st gear is a real stump-puller, so there’s no downside to the rear axle swap. Replace axle and nose bearings and seals on used units you source from a recycle yard (or SLML classifieds). Also check for new 3.27:1 or 3.46:1 ring & pinion gears though correctly shimming new parts is an art. W113 engines are strong enough to pull the taller gears, and these modifications will get your revs down 18% to 21% in all gears. I once had a 280SL converted by Paul Kaminski’s Star Service Co with a 5-speed Getrag gearbox from a Euro 280CE, but it involved a lot “engineering”.
Wind noise: You may have noticed that the cars are much quieter with the hardtop installed than with the soft top. Assuming that you use the soft top most of the time, take the door panels off and adjust the windows so that the glass fits snugly against the soft top frame rubbers, Get new rubber seals if yours are not compliant. Almost all 280SLs I’ve driven are noisier at speed with the soft top up than other convertibles. There can be a low thrumming noise from the top fabric that you actually feel if you put your hand on the ceiling at speed. One day I drove a 280SL freshly restored by Dave Twitchell, and found the exception…. no thrumming. Aha! On this car the new soft top had been installed with the fabric bead at the leading edge of the top resting snugly on the chromed windshield header. Checking all the other SLs in our inventory, I discovered that the leading edge of the top fabric was installed raised off the header. These soft top kits that one buys from various sources all seem to be made by the same supplier, probably from the same patterns, so this fit issue is common. A good trimmer can fix this. The soft top mechanism is strong and compact but complex. After 50 years of going up and down so it may no longer be easy to operate. Gernold Nisius (sltechw113.com) has built a jig to straighten/adjust them. If you are installing new top fabric, be sure the top works easily first. There’s a rear wind blocker designed to cure backdraft on open SLs.
Other Noises: Rattles, squeaks, and ride harshness are uncommon on Mercedes. If yours has any, they can be found. Start with the cheap items 1st: tie rod ends & an entire set of rubber suspension bushings. You may find that yours are still the originals! For clunks and bangs, check the exhaust system fit. The popular stainless steel exhausts are harder to weld, so are sometimes just not positioned accurately.
Undercoatings & Sound Deadeners: W113s came from the factory with a lot of sound deadening science already figured out. If you’re restoring yours, its a good idea to note where materials were applied, and what kind. Aircraft-type sound deadening and absorbing materials such as DynaMat and Acoustimat are sold today for automotive use, but for authenticity, I’d reapply the tar-like jute used by Mercedes before adding the newer layers. I recently restored a ’56 VW using all these materials, but did not achieve the level of sound isolation I wanted. After some research, I came up with a soundproofing undercoating called Lizard Skin. Using the recommended four gallons of this stuff under the car and in the engine bay made more difference than the two-layer sound deadening combination that I put inside the car.
Air Conditioning: USA-delivered W113s could be ordered with air conditioning but the system was installed after the cars left the factory, usually at MB’s port-of entry facilities. They were USA-made Frigiking units. Since they were a retrofit, they can now be added or uninstalled if wanted. Similar aftermarket units can be installed. One shop specializing in this is Bud’s of Atlanta (BudsBenz.com). To improve the cooling of original Frigikings, a rotary compressor can be installed. Cars delivered with automatic transmissions have marginal engine cooling ability on hot days if the AC is on, so be sure your radiator and hoses are healthy.
Handling: The W113s are designed with soft springing, generous ground clearance, and not much anti-dive in the suspension geometry. They have inherently good grip, but lean more than newer cars. This can reduce the level of comfort for passengers accustomed to newer cars. The silver bullet here is installing springs with different spec from stock. I used the John Olson Sport Springs at the front and his Progressive Rate springs on the rear of my 280SL. They reduce body lean, can decrease the ride height (optional), and better manage nose-dive under braking. Lowering the car should be done carefully to retain the level stance. Remember that lower profile tires also lowers ground clearance. A four-wheel alignment needs to be done afterwards. In any case, its best to do one change at a time, so the sway bar can be done later if wanted.
Tires: These cars came with 185X14 radial tires. The original Firestone Phoenix 185s had a fairly large section and tread width for the day… about equivalent to a 195/ 75X14. I’ve tried larger 205/70X14s, but don’t like them as the increase in tread width appears to do nothing to add grip, but can be noisier and slightly harsher riding. If you can find 195 x 75(profile) x 14 size, that will get close to the originals. Now add cup holders and cruise!
Alex Dearborn was advocating Mercedes preservation before the MB Classic Centers were born in the USA or Europe! His archives are filled with individual provenance, especially on 1950s and 1960s Coupés and Convertibles. Feel free to contact him directly about your 220, 300 or Pagoda SL via email at “alex (at) dearbornauto.com”