r129 diesel conversion - Page 2 - PeachParts Mercedes-Benz Forum

bkc · #16 07-28-2014, 09:09 PM

And it is off to the shop! (My first time ever towing something. Rented the tow dolly from Millers Rent-All, bought a hitch/ball from OReilly since my HFT triple ball one didn't have the pin hole in the right place for the Jeep...)

(Okay, so it needs a wash. It originally died mid-winter.)

Towed it off to the shop today for the physical alterations to fit the motor and tranny. Motor sits a little too high (turbo and intake manifold would poke through the hood slightly).

My neighbor (a many-decades welder) said he'd be leery of altering the crossmember. He suggested curving the hood bulge a bit more. I suppose that would at least be changeable later for the cost of a hood and paint and then doing the crossmember alterations... I mentioned it to the guys at the shop, although they didn't seem concerned with the crossmember and rigidity.

With the one less cylinder, the bell housing sits about 4 inches further forward, so the front half of the driveshaft needs to be altered (I'm giving them the r129.061 and w124.128 propeller shafts to mix and match or alter).

Drive shafts:
w124.128 (left): 31 inches
r129.061 (right): 23.5 inches

w124 shaft has double flex disc?

Trannies:
w124.128: 722.418 (top)
r129.061: 722.500 (bottom)

mach4 · #17 07-28-2014, 09:49 PM

Quote:

Originally Posted by bkc

Towed it off to the shop today for the physical alterations to fit the motor and tranny. Motor sits a little too high (turbo and intake manifold would poke through the hood slightly).

My neighbor (a many-decades welder) said he'd be leery of altering the crossmember. He suggested curving the hood bulge a bit more. I suppose that would at least be changeable later for the cost of a hood and paint and then doing the crossmember alterations... I mentioned it to the guys at the shop, although they didn't seem concerned with the crossmember and rigidity.

I wouldn't have any heartburn about modifying the crossmember. It's been done many, many times. Obviously it would be better to not modify it, but if you need to go for it. You're not doing proper engineering so just overbuild it as compensation.

One more thing - make sure you keep the centerline of the engine/transmission where the original was. This is because the driveline you're using uses flex disks that need to be aligned almost perfectly. If the engine/transmission is mounted higher or lower or at a different angle you'll need to modify the drivetrain to use u-joints or cv-joints like a traditional vehicle.

In my case I needed to raise the engine 1/2 inch in order to gain subframe clearance on the crossmember then to keep the centerline aligned I dropped the subframe 1/2 inch. That kept the engine centerline in the proper relationship to the chassis/rear end.

Good luck

bkc · #18 10-24-2014, 08:30 PM

Sorry for the long quiet... Was away for about a month, then the shop got an inexpensive option to expand into the neighboring unit, so they semi-closed for renovation for a while, with all "project" cars being on hold.

Got a glimpse of the car end of August, when I got back from my travels. Local indie had fabricated spacers for the tranny-to-driveshaft gap, and had lined up the motor, welded up one mount, and ground down the edge of the crossmember (and his left index finger! - permanent loss of function) to allow it to sit closer back.

Here are some pictures (more commentary afterwards):

tranny mount:

driveshaft spacer:

crossmember (ground down):

crossmember and new mount bases (finished):

engine in place:

motor mount recess: (had to remove some of the foot of the mount arm to better allow for the muffen mount bolt, or so I was told)

motor mount (Jaguar muffen):

motor mount (right side mount in place):

om602 + 722.500:

Starter no longer has space to be removed (just misses being able to extract). Will have to lift the engine about an inch if I ever need to replace the starter.

The car should be back in my home garage in a few days. (Got delayed by needing to work on one of my other cars, and it is Seattle in Fall, so needed to do it inside.)

I was caught by surprise that it took 28 hours of labor (even after I did some of the grunt work once I was back), for a total of just shy of $3,000 after tax and minor parts. But it was way too late to bail on them doing the work by that point. That will really put a crimp on my other projects, since that was pretty much my budget for the *whole* project, and only the three mounts and the driveshaft extension were done... I really hope what he built actually works after all that.

I question whether it would have been cheaper for him to follow my original thought of just sending out the driveshaft to Drivelines NW instead of his taking the time to fabricate the spacers. He didn't seem to have made any attempt at fitting other mount arms, just jumped straight to fabricating new mount plates and modifying the existing arms. And I still need to have coolant lines and such made/found, and track down 90-91 500SL radiator and oil cooler, plus clean and reseal fuel tank. Not to mention all the little stuff along the way, like a new fuel tank strainer, modifying exhaust to connect, etc. Oh, yeah, and finish figuring out the wiring.

In the end, I wish I had played around with options on my own a lot more first, such as mount arms from a w140 SD (the indie completely ignored or, more likely, didn't understand, my notations regarding the w124, w140 and r129 shared components). Then I might have just had to send the driveshaft out to be lengthened. My lesson from this is to not try to have it done while I am away. In the future, any work done by others I will want to be very directly involved in, so I can halt or redirect their choices, or at least get a way better expectation of costs.

Hopefully will get the car running before my next traveling in December! Would really rather keep the 1976 w115 in the garage.

mach4 · #19 10-24-2014, 09:24 PM

Wow, that transmission to driveshaft solution is a disaster waiting to happen. Do yourself a BIG favor and do it right by having a real driveshaft company extend the driveshaft.

ROLLGUY · #20 10-24-2014, 09:48 PM

Quote:

Originally Posted by mach4

Wow, that transmission to driveshaft solution is a disaster waiting to happen. Do yourself a BIG favor and do it right by having a real driveshaft company extend the driveshaft.

Agreed X2

winmutt · #21 10-25-2014, 10:07 AM

*3 on that ds. How long is the existing one, what is the bolt circle diameter and how much longer does it have to be?

KarTek · #22 10-25-2014, 10:09 AM

Quote:

Originally Posted by mach4

Wow, that transmission to driveshaft solution is a disaster waiting to happen. Do yourself a BIG favor and do it right by having a real driveshaft company extend the driveshaft.

X3

If you have no choice but to use a spacer, at a minimum, it should be a billet piece, all one part. Or at a minimum, minimum, there needs to be a couple of 3/8" aluminum plates bridging the spacers and welded into place so they can't twist.

vstech · #23 10-25-2014, 01:46 PM

+1!!!
This guy sounds like a genius. .. lost a finger?

dude99 · #24 10-25-2014, 03:04 PM

I'll just throw further weight behind the "Get rid of that spacer" sentiment. Its a terrible design and puts way too much torque on those bolts\spacers. I would not trust it.

winmutt · #25 10-25-2014, 03:21 PM

Also just noticed the weld job on the mount, I hope thats temporary?

bkc · #26 10-25-2014, 08:29 PM

I was worried when I saw the spacer as well. While I don't know anything about metalworking, I do know something about physics and kinetic linkages, and that looked like it could just twist. Sounds like I am unfortunately correct. I have propshafts longer (w124.128) and shorter (the existing r129.061 with the spacer), both using the same bolt pattern although the w124 has a double flexdisc setup (see July pictures several posts back).

Also, yes, those are the allegedly "done" welds on all three mounts, other than supposedly needing to paint the tranny mount to prevent rust.

I'm feeling like my lack of metalworking knowledge, and trust in this shop that is known for custom cars, muscle cars, etc., has just led me to piss away $3,000 for basically nothing usable...

vstech · #27 10-25-2014, 11:08 PM

Fyi the flex disk in the picture is ruined...

OM617YOTA · #28 10-26-2014, 04:52 PM

Don't let this get you down, setbacks are part of swaps. My entire conversion has felt like three steps back before four steps forward.

If you have documentation about what work exactly the "mechanic" was supposed to do vs. what he actually did do, now that you have your car back, you might consider short-paying him or only paying for what he actually DID do that you agreed on.

Wish you were closer, I'd clean up those welds in exchange for dinner.

Edit: Actually, looking at it more closely, I would grind those motor mounts off entirely and put some gusseting on the back, tying them in with the frame of the car better. My concern is that they're just one flat sheet with a several inch spread. Even 1/4" plate flexes, and with that much weight and all the vibration those are going to have on them over the next couple hundred thousand miles, I'm concerned something will break.

bkc · #29 11-04-2014, 02:25 PM

Sigh. Still waiting for the indie mechanic's flatbed transporter truck to free up so car can return to my garage for me to keep working on it.

Anyway, regarding the flex disc, I assume you are referring to what looks like a crack in the picture? I saw that in person a while ago and looked closely and it is just excess rubber sprue. That said, I do plan to replace both flex discs, just as a matter of safety principle (especially given how many other things on this car were neglected by POs), once it is actually up and running. Don't want to waste the time and money until I know this is going to all work.

As for the motor mounts and such, as with the flex discs, I guess I will just work with it as it is for now and, once it is actually working systemically, will try figuring out new mounts and such. And get the driveshaft properly modified by somewhere like DrivelinesNW once I know where the motor and tranny will end up with "proper" mounts.

Thanks, as always, for all the feedback. Wish this were progressing more steadily (I thought it would be!). At this rate, he'll get the car back to me just in time for it to sit while I am out of town for large chunks of Nov and Dec. Which also means a lot more time my '76 sits outside in the weather and falling branches instead of nicely protected in the garage.

vstech · #30 11-04-2014, 03:01 PM

Quote:

Originally Posted by bkc

Anyway, regarding the flex disc, I assume you are referring to what looks like a crack in the picture? I saw that in person a while ago and looked closely and it is just excess rubber sprue. That said, I do plan to replace both flex discs, just as a matter of safety principle (especially given how many other things on this car were neglected by POs), once it is actually up and running. Don't want to waste the time and money until I know this is going to all work.

I see cracks...