skeletor

Hi. I am currently putting an LS2 6.0 into a 1983 Mercedes SEC Coupe and have found a couple of interesting facts.

1. The engine mounts on the 6.0 (Aussie Commodore/Pontiac GTO) slide straight into the original mounting holes in the Merc. By fashioning custom mounts that lower the engine, (and with a modified front sump), the motor should slot right in.

2. (And the most amzing part) The six speed auto will bolt up to the Mercedes tailshaft without any modification to the flexible coupling. This, however, puts the trans a little too far forward. So, I pulled the front section off the Commodore tailshaft and found that not only do the splines match the rear Mercedes item, but the dustboot fits as well!!!!

3. Doing this slight modification allows the rear Transmission mount to line up directly over the original transmission crossmember. The bolt holes don't line up, but who cares???

With the trickiest part appearing to be solved by both GM and Mercedes, now comes the task of finding out what vacuum lines are not needed and how to plumb the engine and trans wiring into the original loom. I have the ECU, by the way.

Hence why I am here!!!

Does anyone have a "How To" with regard to wiring and any extra bits needed to make this work? Any help will be greatly appreciated.

Schitzo

iTrader: (6)

There is a guy here working on a LS6 into a W126 chassis as well. His username is Mramay. He might be able to help.

mramay

iTrader: (4)

I ended up having to make a custom engine cross member on mine but hope yours fits without all that hassle. I also went to rack-n-pinion steering since the LS6 block just touched the Benz steering gear box. That was a serious PITA.

I have a 4L60E bolted to the LS6 and it was very easy for the local drive shaft shop to weld a GM yoke to the front section of the 2-piece MB drive shaft. Since I'm trying to use the MB shift lever, that's likely going to take a GM (Summit Racing) flexible cable to attach to the 4L60 shaft.

The vacuum lines are pretty easy but the wiring is going to be "interesting". A friend in LA said that removing all the MB wiring that is not needed "is very easy". That said, I need to get him to show me exactly what he did. He's bolted an MB V12 engine into his 560SEC(!) and has already modified his wiring harness. I'm going to be getting John Spears (Speartech) to make me a drive-by-wire harness, which once the MB wiring has been removed, should be very close to six wires to hook up then start the engine.

I'm going to be using the GTO exhaust manifolds because they're block huggers and MUCH cheaper than trying to find or have made some tubular headers. Once the car is running, the headers will come later.

The 560SEC radiator should be enough for the LS6 and I picked up a dual electric fan setup from a Z06 that should be arriving any day now. FYI, use the Delco alternator instead of the wimpy MB 85-amp or 100-amp unit. Use the GM AC compressor instead of the horribly expensive and not particularly reliable MB unit.

Got your email - tell me what else I can do to help you!

skeletor

Mike,

Would it be possible for you to post some pictures of your cross member?

Aso what did you end up doing with the transmission tunnel. Did you use a porta-pack or did you do something else?

mramay

iTrader: (4)

I sent you a picture of the cross member via regular email. The transmission tunnel was pushed out of the way of the 4L60E with a porta-power hydraulic unit. I didn't want to cut the tunnel so moved it over. That MB metal is THICK!!

I have a plastic LSx engine that I must have put into and out of the SEC a hundred times. If you can find one "down under", I'd highly recommend grabbing it.

skeletor

Mike,

Thanks for the info and picture. It was hard enough finding an LS2 down here, let alone a plastic one. I have a good engine hoist, so putting in and removing the engine is no problem.

I pulled out all the interior yesterday. Our aim is to redo it in a black/orange theme. I intend to custom make a new centre console (fibreglass) that will incorporate the commodore shifter, so re-shaping the trans tunnel will be no problem. The climate control is going to be interesting. I am going to relocate the Merc fan buttons out of the way, so I can install an aftermarket screen for dvd's and GPS.

mramay

iTrader: (4)

The MB AC compressor is a POS but the evaporator and condenser seem to be good quality. I'm going to use the GM accessories - alternator, compressor, and power steering pump in the FrankenBenz. For all the touted excellence of MB, the GM units are just as good (maybe better) and cost 75% less.

I'll still use the MB climate control system but I have a generation II SEC, which is different than your Gen I. Find some H&R lowering springs for it. Do NOT use KYB shocks here, only Bilsteins - they are that good. You can get a larger rear sway bar but the front one is all there is, nobody has found a way to get a larger one or even parallel in another one.

There is a guy in AU that is track racing an SEC and would be a great source of suspension info. Go to BenzWorld.org and post a message for him.

560sec

Hence why I am here!!!

Does anyone have a "How To" with regard to wiring and any extra bits needed to make this work? Any help will be greatly appreciated.[/QUOTE]


G'day guys,
I completed this conversion about six months ago. I used a second hand ls1 from a commodore with the 4L60E auto. Note that modifications to trans tunnel are required. I also custom fit a commodore LSD diff to a modified rear K frame and made custom bittet CV shafts. I did this because my mercedes LSD is of clutch type and will single spin once traction is broken (not good for burn outs) I made custom engine mounts from 6mm steel plate. Custom rack and pinion steering was also made but is still a problem with bump steer. This is because of the suspension setup, made worse because the mercedes needs 7 inches of travel to get lock to lock in order to turn tight corners. Wiring is the least of your problems once the VAT is removed from the computer. Combine all of this with a large stall converter and i have a low twelve second car without a cam.

I will get my brother to post pics and a video on you tube for you guys to see.

skeletor

Well,

Good news!! After a week of second guessing my decision and questioning my sanity, I removed the stock steering box and linkage and made the new crossmember on Saturday and welded it in. The motor is as far back as I can take it. The 6l80e transmission is in and, after drilling two new holes in the Mercedes mount, is bolted into place. Isn't it nice that mercedes provided 3 different mounting positions for the crossmember. The added bonus is that, (for now), I can use the stock Commodore engine pipes and Cats.

The next stage is the rack and pinion. After supplying careful measurements to an Aussie steering specialist, a VR Commodore rack was chosen. Apparently, this has all the right dimensions and with careful mounting, should hopefully eliminate bump steer.

The wiring is worrying me. Could Mike or 560 explain what I need to do to make it work. As mentioned I have a 6l80e trans, so I will need the TCM as well, won't I? I am also going to use the drive by wire pedal, (which I have), so I am going to need that loom as well.

Pictures to follow soon.

Gusthewonderslug

Skeletor
How did this swap end up.
Gus
Ps I'm in Perth and keen on the same swap

jimmy92rs

Interesting swap. Good luck with it.

hoboy

this makes me want to swap out a dead 500SEC I have had for a few years now. I know the exhaust is the biggest hurdle I have heard people talk about. How is this project coming along these days ?

TipsyMcStagger

iTrader: (1)

The OP hasn't logged-in to this site since 2009.

Tipsy

jimmy92rs

Word!

dman

iTrader: (5)

to keep this alive I'll post up pics of the 500 SEC i just bought. It has the rack mod and I'll take some pics this weekend

LS1 / T56

adazspace

Hi guys
Im new to this forum but have been chasing info on fitting a ls1 in a w126 Mercedes.
Could any body give me more info and pic on rack & pinion conversion to do this engine conversion.
Thanks

brawls43

I don't think there's a lot of info out there. I've seen some patchy info on some M-B forums. And there was a guy here that did a W123, but I don't know how his steering modifications worked out. I'm trying to plan a W123 LS swap, but haven't really gotten started yet.

gear-head

gear-head