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Project BADwagon 1984 300TDt Om606 6 speed
I've been plotting and planning while squirreling away parts for an everyday fun to drive manual trans hot rod diesel car/work truck ish tow vehicle forever and have just ended up using my 300sd and sdl with no back seat with grand plans for an elcamino type build from the sdl. It's toast. In just about every way. Electrical gremlins, the om603 just bit the dust and really the killer of all is just tons of rust in structural areas and body work.
So here's the new plan. I picked up a rust free(for the most part, a couple little issues) w123 wagon for 400$ , it's pretty amazing. Granted it needs alot of tlc and some accident damage in the rad support fender lip area fixed, buy my welding skills are up to it. The front suspension will be the best of what's in the car and what is currently in my 300sdl w126 chassis. This includes the 300mm vented front disc brakes and very likely the front sdl springs relived of at least one coil possibly more. For those who don't know the w126 and w123 share all the exact same suspension components from the inner control arm bushings out so that's all direct bolt on swap from dinky solid rotors to the nice large gen 2 w126 brakes. If any bushings look bad I'll change them. I'm not sure if I'm going to make delrin control arm bushings for this car yet. Kyb shocks are fantastic and affordable. The drive train is where it starts getting good. Engine is a 1999 om606. Hx35 or 40 turbo to push 300-400 hp with supporting injection pump. It's capable of more but unnecessary. The trans is a 6 speed manual 716.668 from a 2001 c230 kompressor and I just got a 2.82 ASD 210mm ring gear (same as all v8 car diffs since 1973 or so) differential from a 350SDL W126 gen 2 car. This is a computer controlled hydraulic actuated differential locker that is a limited slip differential until the computer would apply hydraulic pressure to a separate system that locks the clutches and the limited slip. Rather than swap in all the complex system to operate it when the car seems its proper, I'll have a small master cylinder with check valve to Pump it Up and a release so I can simply lock the rear wheels together when I want to get some extra towing grip or force the car into drifting duty. The tricky part here is that the gen 2 w126 differential does not have the same mounts from the case to the subframe, and a w126 subframe does not fit into a w123. So after much head-scratching and staring at parts laying on my shop floor I've got it figured out how to get everything attached and sitting in the exact correct position. The gen 2 w126 and r107 (86 and up)use the same newer style differential/subframe mount system which, instead of using the diff cover as the only mounting point for the rear of the subframe to the crossbeam in the car by four bolts, uses a large section welded onto the top of the subframe and has an arm (yellow marking) that reaches back that connects to the standard type rear subframe mount and then to a different style differential rear cover that has a provision(which attaches under where the green arrow points) to be bolted to the bottom of this arm (yellow) protruding from the top of the subframe. The red dots are the 4 hole areas the w123 and gen 1 w126 gen 1 diff bolts in. Since the w126 and w123 subframes are very similar but not the same overall track width I can cut the rear/top section off the w126 subframe and attach it to the w123 wagon subframe. If I bolt a gen 1 type 4 bolt 210mm into the wagon subframe with a gen 2 style rear cover on it i will be able to positively locate the cut off section of w126 subframe and allow me to trim and fit/weld the new section on to the w123 in the right place. A small jig that bolts to the flex disc yoke and the subframe will positively locate the front section. Once they are in place I can remove the gen 1 diff and install the gen 2 diff and use both mounts, it's original rear mount and the flex disc yoke, to locate the diff where it will live. I can now weld in the plates that the forward mounts bolt to on the bottom of the subframe. Once that is done the flex disc yoke jig will be removed and the diff will mount exactly as it would have if a gen 2 w123 was ever built. The actual rubber insulated rear mount that attaches to the cross beam in the car has a four bolt pattern as well. On the gen 2 type mount it shares the same left side holes in the chassis but in it's right side holes. The other two now offset to the left will have to be drilled and use another threaded insert bar If they are not present. It seems a little drastic maybe but to be able to positively lock the rear axle is a great thing for me. I would just weld the diff since the LSD are not the most spectacular in operation and I am a drifter, this car will tow my drift car and should I break it severely at an event I will drift the wagon for the rest of the day. Towing on a welded diff is not really a great idea. Nothing more lame than a one wheel burnout too. The 6 speed trans and flywheel from the supercharged m111 4 cyl bolt right up to the om602/603/606 and m102/103/104 family of engines. I'm having an injection pump built (really the last piece of the puzzle) by either benzforce or diesel pump UK. The stock 603 pump and my propane injection kit will be good for the time being if I don't have it on hand yet. This engine has been installed in the w123 chassis by a few different people. I've done lots of research and got lots of info on what's necessary. Some custom mounts are no problem, some oil pan trimming is probably required as well. My new Tig welder will come in handy there. I haven't decided if it will get antisquat rear suspension from a r107 or w126 yet, but it will definitely have all the same delrin goodies I have in my drift car. Subframe inserts, control arm bushings sway bar bushings, all to keep rear sway under control while towing. I've got some custom body work planned from my very first Mercedes which was a 300td. Modified nose with a w108 grill and split bumper. Some hand made AMG ish side skirts and a small euro coupe rear bumper. 17" wheels I'm pretty sure. I love my 16" rial n weave but they are just dinosaurs and far as tire selection. I've got tons of wheels so that is still up in the air. Just getting this started so I'll have a list and can check them off. I bought the car in Boston a couple years ago and dragged it home and parked it. It ran but overheated. No vaccum system operating. I just got the car running driving and stopping with a thermostat, vaccum pump repair and some Electric window switch cleaning. It has SLS delete and had really cheap SENSEN shocks that were totally blown out. Only buy them in an emergency, they really are garbage. I threw a used shock in the driver rear since that one was ding nothing but rattling around. I have kyb w126 front shocks going in and probably in the back. I have some air shocks that I may install but I need to see how the rear sits first. Here we go. This should be fun. 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WARNING!!! VINTAGE MERCEDES MAY MULTIPLY UNCONTROLABLY!!! I have tons of Sl/Slc parts w108 w111 w126 and more. E-mail me with needs BirchsgarageMB@gmail.com |
#2
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Just curious, but would the 560sl rear subframe be better to line things up for the mount because the mount width is probably the same as the c107 and w123?
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Past mb: '73 450sl, '81 280slc stick, '71 250, '72 250c, '70 250c, '79 280sl, '73 450sl, parted: '75 240d stick, '69 280s, '73 450slc, '72 450sl, |
#3
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Quote:
They have no bearing on where the diff needs to be in relation to the control arms and hubs. The only thing that matters is that the outputs of the diff and the front flange for the driveshaft are in the same place as the original gen 1 diff. I will install the gen 2 diff rear cover with the offset mount provision on the gen 1 diff(which would originally have the centered mount bolted directly to the diff cover) and install it in the w123 subframe by the 4 studs(red dots that you can see the gen 2 diff doesn't have). This will allow me to bolt the added on gen 2 subframe mount arm(yellow triangle in the pic)to the diff cover after cutting it off the w126 subframe and trimming it to get it to fit the w123 subframe for welding. Then build a jig to bolt to the drive flange and weld or bolt it to the subframe. Once that is all done the diff comes out and the gen 2 cover goes back on to the gen 2 diff. It will now bolt into the w123 subframe by the drive flange and the diff cover and I can now build the front mounts up on the subframe to where they need to be and it will all be perfectly lined up. I'll need to pull the diff one last time to finish weld all of it and paint it. The new portion of the subframe has the holes that the big offset rubber and steel mount bolts on to instead of being centered and bolted to the diff cover on the gen 1 w123 type mount. I'll try to document it when it's getting done. Sent from my SM-J737A using Tapatalk
__________________
WARNING!!! VINTAGE MERCEDES MAY MULTIPLY UNCONTROLABLY!!! I have tons of Sl/Slc parts w108 w111 w126 and more. E-mail me with needs BirchsgarageMB@gmail.com |
#4
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I thought a picture of a gen2 installed in a car would help me to understand.
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__________________
Past mb: '73 450sl, '81 280slc stick, '71 250, '72 250c, '70 250c, '79 280sl, '73 450sl, parted: '75 240d stick, '69 280s, '73 450slc, '72 450sl, |
#5
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If you can mount a gen2 cover to a gen1 diff, I assume you can mount a gen1 cover to a gen2 diff. The problem is that it doesn’t have the studs to mount the gen2 diff to the gen1 subframe. Correct?
__________________
Past mb: '73 450sl, '81 280slc stick, '71 250, '72 250c, '70 250c, '79 280sl, '73 450sl, parted: '75 240d stick, '69 280s, '73 450slc, '72 450sl, |
#6
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Correct. That would only make a diff you could hang from the car and nothing else. I'm ONLY doing this to use the diff as a jig to modify my w123 subframe. You can't even bolt it into the car with out the modified subframe since the gen 2 cover bolts to the subframe and not the rear mount. But now I think about it I should be able to swap back to a gen 1 diff with if I ever want to. So that's nice.
Sent from my SM-J737A using Tapatalk
__________________
WARNING!!! VINTAGE MERCEDES MAY MULTIPLY UNCONTROLABLY!!! I have tons of Sl/Slc parts w108 w111 w126 and more. E-mail me with needs BirchsgarageMB@gmail.com |
#7
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I've been using the wagon for a couple days. Unfortunately my 300sd daily started making some bad noises. It broken odometer with 274,000 a long time ago. I think it's a rod knocking. It was a real ***** to start on Thursday morning and it was far above freezing. It made some weird kickback events and I had to jump it. It felt a little low on power and after work driving home I heard some knocky rattley noises. I was hopeful it was valve train but it's not. UGH. I changed the oil after flushing the motor with mineral spirits thinking I could have a low oil pressure issue. Sounds better but it's still noisey. I don't have much faith in it but who knows how long it will run. This wagon runs strong and good but I think it's got a little leaky headgasket going on. Full pressure in the cooling system the next day. The rear driveline is a mess. The axles have bad boots and the diff is super sloppy. I've got a brake making scraping sounds and the tires are all low tread drift leftovers I didn't fully kill which are unbalanced so it's got some pretty good shimmy. I do love having the wagon again though. The SLS delete is pretty stiff but I'm fine with that. 8 batteries in the back for a AutoZone drop off git me a 10$ 5 gal rotella bucket. I can't wait to have this all redone. Being that I don't trust it fir a long run I just pulled my w115 240d 4 speed I bought non running in to the shop to tinker with. I can't start tearing down the wagon till I have a daily I trust. Figures some **** like this goes down.
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WARNING!!! VINTAGE MERCEDES MAY MULTIPLY UNCONTROLABLY!!! I have tons of Sl/Slc parts w108 w111 w126 and more. E-mail me with needs BirchsgarageMB@gmail.com |
#8
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Why not just put a modern rear subframe in it with everything that fits? It would be easier than what you are doing. Like a 202 AMG car or something with limited slip.
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#9
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Quote:
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__________________
WARNING!!! VINTAGE MERCEDES MAY MULTIPLY UNCONTROLABLY!!! I have tons of Sl/Slc parts w108 w111 w126 and more. E-mail me with needs BirchsgarageMB@gmail.com |
#10
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Quote:
I was thinking in particular about Pyry Takkunen redoing his w108 with a w202 subframe or similar; can't recall exactly what he used but it looks very similar to a 124 setup: https://www.instagram.com/p/CEhbzRcJqIY/?utm_source=ig_web_copy_link. You would get much more modern suspension geometry. A 123 is just not in the same league as a 124 or later car with multi link rear suspension. |
#11
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Is that SDL ASD differential the same style case differential that’s used in a w124 or a r129 ? I’m just asking because Jason does have both of those rear ends in his shop. If it’s truly not that much body work to make the subframes mount in, then maybe it is worth consideration. Jason sounds like he’s got his mind made up though.
I know that nothing felt as “planted” as my 1992 500sl r129. But does the R129 and/or w124 rear suspension utilize the anti-squat / anti-dive technology? While the trailing control arms result in different wheel angles at different spring compressions, they do operate a bit like they have an upper control arm as the axle is able to rotate on the control arm, unlike a w123 or really any 6 cylinder trailing control arm. Since the 6 (and smaller) cylinder cars before the W124s didn’t use the anti-squat technology, I wonder if the w124s did. Maybe a bit of an overview of the anti-squat vs standard vs r129 vs w124 rear suspension would be worth reviewing here (while Jason just welds up that subframe anyway).
__________________
Past mb: '73 450sl, '81 280slc stick, '71 250, '72 250c, '70 250c, '79 280sl, '73 450sl, parted: '75 240d stick, '69 280s, '73 450slc, '72 450sl, |
#12
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No, the 124 v8 diffs are a totally different case than the 126 case. The r129 sL and w124 diffs are the same, at least for v8 cars. If going 606 with a big pump and turbo, getting a 124 v8 diff and half shafts makes lots of sense. Or just plug LSD guts into the 123 pumpkin.
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#13
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Quote:
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__________________
WARNING!!! VINTAGE MERCEDES MAY MULTIPLY UNCONTROLABLY!!! I have tons of Sl/Slc parts w108 w111 w126 and more. E-mail me with needs BirchsgarageMB@gmail.com Last edited by rwd4evr; 01-21-2021 at 05:50 PM. |
#14
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Quote:
As far as "plug the guts into the w123 pumpkin", the w123 housing is a 185mm. I could use a r107/w126 v8 housing, but the fact that the side spacers and pinion spacers are listed in the epc with .05 mm increments to set the gear lash I'd be much happier to modify the subframe which I'm 100% confident will work without a problem. Plus the main reason is to have the ASD hydraulic locker at my disposal. No gen 1 cars ever used ASD so it wouldn't be usable. I am picking up a second 3.69 diff and I would love to build a 3.69 or 3.46 ASD LSD diff for a street/drift car without a welded diff. But the 3.46 LSD I have is too valuable to take apart really. Sent from my SM-J737A using Tapatalk
__________________
WARNING!!! VINTAGE MERCEDES MAY MULTIPLY UNCONTROLABLY!!! I have tons of Sl/Slc parts w108 w111 w126 and more. E-mail me with needs BirchsgarageMB@gmail.com Last edited by rwd4evr; 01-21-2021 at 06:02 PM. |
#15
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Now that sounds like maybe a reason to build that r107 drift car. No custom subframe required, when you can just use a 560sl rear subframe.
__________________
Past mb: '73 450sl, '81 280slc stick, '71 250, '72 250c, '70 250c, '79 280sl, '73 450sl, parted: '75 240d stick, '69 280s, '73 450slc, '72 450sl, |
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