Buyers Guide 1957-2002 Overview of SL Roadsters

Buyers Guide - Mercedes-Benz Roadsters
Overview of the 1957-2202 Production SLs
 
Oh, the joys of top-down motoring in the brand that offered a flair for elegance and a commitment to innovation in each decade. No other manufacturer offered the safety features, engineering, and reliability of the SL roadsters.

This buyers guide covers the W121 (190SL), W198II (300SL Roadster), W113 (230/250/280SLs), R107 (350, 380, 450, 560SLs), and R129 (300SL, 500SL, 600SL, SL320, SL500, SL600) for the American markets, not European models. It does not include the W198 300SL Gullwing Coupe, the R107 SLC or the SLK series.

Let’s start with an understanding about Mercedes-Benz terminology.  Roadster in most of the automotive world means a vehicle with a removable soft top. Convertible or cabriolet refers to an open vehicle with a soft top and roll-up side windows. However, in Stuttgart-speak, a roadster has a soft top that goes down flush into the rear deck; a cabriolet has a soft top that folds down, but when folded sticks up quite some distance from the rear deck .

SL (Sports Leicht in German) means, in essence, sports light. However, compared to “sports cars” of the time, the SLs after the 300SL Roadster were not light. They ranged from 2,557 pounds (190SL) to 4,615 pounds (600SL). In the 1950s, many sports cars  weighed around 2,000 pounds. We can safely say the SLs were substantial – then and now.

Sports Car in usual classic car parlance means high-performance, but hard-riding, cramped, often unreliable, and not practical as a daily driver. By contrast, Mercedes-Benz believed that a sporty roadster could be comfortable and reliable for long-distance touring, but with a bit of a wicked personality for handling and responsiveness. The SLs were used in motorsports, but more often in long-distance endurance races than shorter track races because they could finish when other brands would end up DNF (did not finish). Yes, it’s a different attitude about the meaning of a sports car!

All SL Models were equipped with a hardtop and roadster tonneau cover. Early models had a canvas softtop and later models had a retractible hardtop.

 

Reasons to Buy, All Models

The SL lineup has stood the test of time with all models still actively enjoyed. Positive attributes shared by all models include:

• Timeless design
• Reliability
• Comfort
• Availability of most parts (M-B Classic Centers in Germany and the United States) or aftermarket
• Fully synchronized manual transmissions on W121s and W113s (4-speed with some 5-speeds on W113s)
• Excellent automatic transmissions used extensively on W113s and exclusively on virtually all later models in the U.S. market (for those seeking a
• great touring roadster)
• Modern amenities (power steering, early adoption of antilock brake systems, airbags, air conditioning, power windows, AM/FM/Cassette/CD audio systems, and so forth)
• Safety, safety, and safety that improved over the years (crumple zones starting with the W113s in 1963 and subsequently more features with use
• of high-strength alloys)
• The removable hardtop is so strong the SLs can be used on the track with it in place (no separate roll bar is required)
• Automatically deployable roll-over protection starting with R129s in 1990
• Comfortable for long distances with a usable trunk for luggage
• Relative affordability (except for the 300SL Roadsters)

Reasons Not to Buy, All Models

Admittedly, there are some reasons why the SLs are not suitable for all owners. Across the lineup, these include:

• All models through R107s have a propensity to rust – Any 190SL that has not been restored will have rust; it’s just a question of where.
• Regular, quality service was required at frequent intervals
• Aluminum engine parts – especially heads – were susceptible to corrosion due to inadequate replacement of proper coolant
• 190SLs do not have substantial horsepower
• Gearing (high rpm at highway speeds on all W121s and W113s) and abrupt shifting on W113s with automatic transmissions
• Automatic climate controls on R107s from 1977-1981 can be troublesome (see pages 58-60 in this issue)
• Single-row timing chains on R107s from 1981-1983 (not a problem if service records show that they were replaced every 100,000 miles or replaced with the double-row timing chains that are the only parts available from Mercedes-Benz today)
• Drivability issues with 1975-1977 R107s (450SLs due to emission regulations and pre-K-Jetronic fuel-injection) and with the 1990-1993 R129s (300SLs only)
• American-style bumpers introduced on R107s in 1974 (450SL through 560SLs) are safer, but not considered attractive by some buyers/owners
• Biodegradable wiring harnesses in 1993-1995 (a German government requirement) do biodegrade and are quite expensive to replace if they have not been replaced already
• 600SL and SL600s (R129s) have complicated engines, adaptive damping systems, and staggered wheels on some models that are extremely expensive to maintain or replace

Model by Model Checkpoints

Following are key checkpoints for each specific model. For more detail, refer to Buyers Guides available at mbca.org.

W121 (190SLs)

• Rust is the biggest threat. Double-wall construction of the unit body allows rust to develop and rust inhibitors were not regularly used in the ‘50s and ‘60s. This may be a deal-breaker if rust damage repair costs exceed the potential value of the car. Caveat emptor.
• Poorly repaired body work is not only another contributor to rust, but getting everything aligned in a unit-body vehicle is made more difficult if structural elements were not repaired by a person who knew how it should be done properly.
• Look for the dates stamped on the wheels to determine if the car is substantially original or if it was a project car. This is a very helpful clue to making a good purchase.
• Review the “data card/build card” (or a replacement that can be provided by the MBUSA Customer Assistance Center) to verify the numbers on the steering box, left and right front axles, rear axle, engine, and transmission are correct.
• Check for completeness: missing components may be available for purchase but may come at the proverbial king’s ransom. The more you know about what the car should look like, the better your chances of getting a complete car.
• Test drive the vehicle and, if possible, have a knowledgeable mechanic perform tests, such as engine leak-down, compression, tightness of the front sub-assembly, rear axle noise, leaks, brake system condition, lights, clock, radio, and so forth.
• Confirm that original Solex carburetors have been professionally rebuilt and installed. Most bad press around these carburetors is a result of poor maintenance. Substituion of Weber or Mikuni carburetors is a deduction in concours d’elegance judging.

W198II (300SL Roadsters)

• Check for completeness and provenance with a knowledgeable specialist, restoration shop, or member of the Gull Wing Group International.
• Have a thorough inspection by a knowledgeable mechanic who is familiar with the 300SL models and can give an honest assessment about the one you are considering.
• Inspect for rust on steel parts; bondo on all parts (difficult to detect on the aluminum body parts used on hoods, doors, and trunk lids). Rust is likely in the headlight buckets, in sheet metal behind the rear wheels, and deeply hidden in the tube frame.
• Look underneath for presence of aluminum belly pans, removable and not always replaced by mechanics.
• Smell the engine oil for gasoline (fuel injection set too rich).
• Check oil pressure: At 65-75 psi at speed and at least 20 psi at idle.
• Confirm intake manifolds are bare matte-finish metal (not bead blasted to look like chrome, indicating lack of care with other details).
• Confirm valve covers are painted black as original.
• Test drive any 300SL for smooth operation. One big risk is deteriorated fuel injection pump and injectors due to lack of regular use. It is an expensive component to rebuild.

W113 (230/250/280SLs)

• Rust around headlights, fenders, door sills, and floor pans because of unibody construction and lack of rust inhibitors can be the deal breaker on any W113.
• Missing trim pieces are increasingly difficult to obtain, but can be purchased from both the MBUSA Classic Center or aftermarket, priced like the rare earth element Unobtainium.
• Look for alterations that can seriously affect value, including after-market transmissions or overdrive units that owners have installed to reduce engine rpm at highway speeds. Note that these under-square (Stroke shorter than piston diameter) engines were engineered to run all day at high speeds and still last well over 200,000 miles before a rebuild. Other replacement items, such as radios, under-dash air-conditioning, and incorrect upholstery, carpeting, and convertible tops are fixable, but lots of wrong items add up fast.
• There were W113 models with soft-top only, hardtop only, and both tops. Confirm with an expert that the model you are considering has everything it is supposed to have.

R107 (350/450/380/560SLs)

• Cracks at the attachment points on the front sub-frame (1972-1980 models). Most have been repaired under recall, but confirm with records and by visual inspection.
• Rust in the frame rails, front fender, the HVAC blower box, and battery box in the trunk.
• Timing chain, upper chain guides, chain-tensioner, and cam lobes for excessive wear.
• Cooling system overheating, especially on 1974-1977 models because the catalytic converters were in the very cramped engine compartment – adding to under hood heat.
• Automatic climate control systems (1977-1981).
• Water damage in the interior; they were not as watertight as they should have been.
• Aluminum block engines are prone to leakage at their head gaskets.
• Oil pans are cast aluminum and can crack/leak if damaged by a curb or severe pothole.
• Airbags in 560SL are supposed to be replaced every 10 years.
• D-Jetronic engine management systems can be a problem unless adjusted by a mechanic who is knowledgeable about how they operate.
• Seek complete service records to be sure that the car has been regularly maintained and that coolant flushes and so forth have been done at proper intervals.
• Test drive any R107 with a knowledgeable mechanic, restoration shop, or club member who knows how it is supposed to operate. R129 (300SL, 500SL, 600SL, SL320, SL500, SL600)
• Mechanical issues, such as biodegradable wiring harness, head gaskets on early 300SLs, 5-speed automatic transmissions on 500/600SLs, instrument cluster failure (LCD readouts and mechanical odometers), models with ASR (Acceleration Slip Regulator – an early form of stability control).
• Wind-protection screen (starting in 1993) is stored in the trunk held by three snaps and is needed to provide draft-free top-down driving at highway speeds.
• The removable hardtop that came with the car should be there. Due to changes in A-pillars, hardtops are not interchangeable.
• If the “data card/build card” indicates that the car came with a Panoramic Hardtop, be sure it is available. It is very expensive to replace and not all are interchangeable.
• 300SLs (R129s) have very finicky 5-speed automatic transmissions that are expensive to maintain. Make sure the transmission is in good operating order, or avoid this model.
• Evaporators on A/C systems should be checked carefully, and may require repair or replacement if they haven’t been serviced recently.
• Soft top control unit and hydraulic cylinders are failure-prone. Check the operation to make sure the top raises and lowers smoothly and the rollover bar should work properly.
• Determine if it is a special edition (Mille Miglia Edition, Designo Edition, 40th Anniversary Roadster Edition-1997, Special Edition-1998, Final Edition-2000, SL Edition-2000, Silver Arrow Edition-2000). In 1990-1992, a few 300SLs sold in the United States had a 5-speed manual transmission. These can be more valuable.
• If there are AMG badges, be sure that it is really an AMG model. New badges are easy to apply and you could pay for something you are not getting.
• Test-drive the vehicle with a knowledgeable technician and check service records for proper and timely servicing.
• The R129s have become “old cars” and the pricing indicates that they are not yet considered as collectible. So, if the styling and features appeal to you, this is the prime time to buy into your very own Mercedes-Benz SL.

 


Value Guidelines

• A Condition – Potential class winner at regional concours
• B Condition – Safe and attractive for club events
• C Condition – Complete but requires repair or restoration

For More Information
Many books have been written to help SL buyers, including the following:

Adams, Bruce L. Mercedes-Benz 190SL: 1955-1963 Restoration and Ownership. 2003. ISBN: 0-9729-4200-9

Adams, Bruce L. Mercedes-Benz 190SL: 1955-1963 Restoration and Ownership Volume II. 2007.
ISBN: 0-978-0-9729420-1-0

Adams, Bruce L. W121 Coupe and Roadster: The 190SL Touring Sports Car. 2011. ISBN: 978-0-615-44458-1

Barrett, Frank. Illustrated Buyer’s Guide: Mercedes-Benz Second Edition. 1998. ISBN: 0-7603-0451-3

Larimer, Fred. Mercedes-Benz Buyers Guide Roadsters, Coupes, and Convertibles. ISBN 0-7603-1811-5

Long, Brian. Mercedes-Benz SL W113 Series: 1963-1971, 2011. ISBN: 978-1-845843-04-5

Meredith, Laurence. Original Mercedes SL: The Restorer’s Guide to 300SL, 190SL, and 230/250/280SL Models to 1971. 1996. ISBN: 1-870979-66-4

Nitske, W. Robert. Mercedes-Benz Production Models Book 1946-1995. Fourth Edition. 1995. ISBN: 0-7603-0245-6

Olson, John R. The SL Experience: Five Decades of the Mercedes-Benz SL. 2001. ISBN: 0-9635394-2-6

Note: Buyers Guides for all SLs, except for W198 300SL, have appeared in recent issues of the Star, and can be referenced at www.mbca.org.
W121: Nov-Dec 2010       W113: May-Jun 2011
R107:   Sep-Oct 2009        R129:  Jul-Aug 2010

TECHNICAL SPECIFICATIONS | 1955 - 2002 SL Roadsters

* Manual transmission available as option      ** After substitution of U.S. safety bumpers in 1974