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Conversion from SL280 to SL55


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Hi, I don't post much on this site, but I notice a lot of similar-minded folks that want to "have a go" at customising their Mercedes. I decided to film the AMG 55 engine swap in my 2000 R129 SL280 V6.

I've researched this before picking up a tool! hours in Mercedes part catalogues and wiring diagrams.

The R129 has the M113 5-liter engine, which looks like the AMG naturally aspirated M113 V8 engine. The R129 "SL55" used this AMG engine from 1998 to 2000. Everything should bolt-in.

So far:

1. 2000 CLK55 engine, gearbox, wiring loom and ancillaries.
2000 SL500 ME2.0 engine ECU
SL500 gearbox ECU (2000).
Fan shroud SL500.
5. Rear differential.

The drivetrain—propeller shaft, driveshafts, and rear differential—causes the most trouble. The AMG transmission's final drive ratio of 1:2.82 is incompatible with my SL280 differential. The CL500 and other era AMG vehicles use 1:2.82 differentials. Most "500" and "320cdi" versions employ a 1:2.65 ratio, while the SL500 uses the W220 case for its bigger driving gears. My SL280 utilises the W210 housing like other V6 models. I utilise a CL500 differential with a 1:2.82 final drive ratio, E320CDi driveshaft flanges (like the E55 and CLK55), and an SL500 mounting plate to make a "SL55" differential. I got a late 2002 SL500 mounting plate from a U.S. breaker to finish the assembly since I couldn't find one secondhand in the UK or Europe and it costs £400+ from the dealer.

My W210 E55 driveshaft assembly may remain. V8 drivetrains have 110mm PCD flanges, whereas 6 cylinder drivetrains have 100mm PCD. The gearbox flange on early 500s and AMG versions had 4 fingers, whereas all others were 3.

The back of the vehicle has been worked on, including removing the rear exhaust, the original differential, and corrosion and rust protection. Due to a corroded rear brake line, the job started a month early. While the diff was out, new copper brake lines and fuel lines were installed.

The engine and front of the vehicle are my attention while I wait for the diff rear plate. The engine schematics show that the CLK55 utilises ME2.8 injection and a different throttle control actuator than ME2.0 systems. The throttle component may be utilised from my ME2.0 V6, however the MAF is physically different.
SL500 ME2.0 ECUs will start the engine. If the C43 ECU can run a 55 engine with 1200cc difference, then certainly a 500 ECU can operate a 500cc engine? I'll need to have the unit "virginised" for £70 to acquire an ECU that works with the DAS2b immobiliser system.
The AMG 722.636 trans will operate on an SL500 gearbox EGS, which should be compatible with the ABS/ESP/BAS systems.

Conversion from SL280 to SL55

Edited by IrvesBMW
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3 minutes ago, ForumGuru said:

I didn't aware the r129 had a 5.0L m113 engine; I assumed it had a 5.0L m119.

The R129 was made from late 1998 to 2001 (in the US, 2002), and it had the M112 V6 and M113 V8 engines and all the newer ESP and BAS systems that the W210 and W208 had, but it kept the older immobiliser system with the switchblade key.

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I've already spent many hours this weekend disassembling the components around the engine. A/C condenser and radiators were removed. engine oil and coolant were drained. Power steering lines, an alternator, and top bolts on the engine mount were all removed. Draining the gearbox, removing the exhaust downpipes, the prop-shaft flange, the earth strap and ultimately the rear gearbox mount are yet to be done.
There will be some different pins, thus some soldering will be required. I'm going to remove every pin from the ECU connections and then insert the pins from the CLK55 engine loom.

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