560SL subframe removal questions - PeachParts Mercedes-Benz Forum

donbryce · #1 01-25-2008, 08:51 AM

I've decided that I'm going ahead with removing the subframe, instead of just replacing the 4 shot mounts, since it doesn't look like much extra work to do so. I read where another member did this, replaced all the mounts, and the whole job was only about 5 hours. I'll probably clean and paint as well.

The shop manual is pretty clear on how this is done, but here's a few things that aren't so clear, which ought to be to anyone who has done this job:

Q1 - To avoid the hassles of brake bleeding, I'm thinking it would be easier to remove the calipers and hang them from the body/wheelwells. The manual addresses uncoupling them, with all the ABS and sensor wires, but this shouldn't be necessary, right?

Q2 - After jack-standing the car, and with a jack under the lower A arm, I should be OK to remove the shock, then lower and remove the A arm jack, leaving the springs in the assembly, as shown in the picture (of another subframe), right?

Q3 - What is the best way to support the engine before uncoupling the engine shock absorbers and the engine mounts from the subframe?

Q4 - Related to the previous ?, the manual talks about removing the 'left and right metal shields from the exhaust manifold'. I suspect this is to avoid bending them when using the official 'engine carrying stirrup', true, or is there some other reason? They don't cover anything on my engine except the manifolds....or do they mean the shields over the mounts??

Gurunutkins · #2 01-25-2008, 10:12 AM

all looks correct to me, I had to remove the exhaust covers to get a long extension bar down to the engine mounts, I could see them but the angle was too far off to get a decent grip on them. I pulled the engine using a 4x4 by 8 ft beam in the joists of my roof so i spead the weight over 5 roof beams. generally roof beams are way over designed as they are spec'd to withstand the pressure of wind at 70mph or 3 inches of snow etc so an 800lb engine and tranny spread over 4 or 5 beams is generally not a problem, the optimum of course would be an engine crane but then you cannot get under the car to pull the sub assemby so you have to support it from the top, catch 22!
good luck
Barri

donbryce · #3 01-25-2008, 02:47 PM

I have a 1/2 ton chain fall on a ceiling mounted track that I normally use to pull engines. What I want to know, I guess, is if anyone has set up a beam that works like the Mercedes rig, resting inside the engine bay (on the body frame rails, or shock towers??) so that the car's position can be changed in the garage, independent of it's position relative to the ceiling.
To use the chain fall, I suppose the hood hinge pins can be removed and the hood raised enough to clear the chain, which could be attached to the suspension eye on the thermostat housing? But I'd rather use something like the recommended 'engine carrying stirrup' (which would be appropriate if you had a hoist, I guess), and wondered how this was secured.
For the engine mounts, I thought you went up inside a hole in the subframe to remove a hex head bolt from the underside? There are no 'shields' on my 560SL blocking access to these holes. Are these the oil shields, on the top of the mounts, held by what looks like a large 17mm or so nut?

Gurunutkins · #4 01-25-2008, 03:07 PM

on mine neither of the bolts (one each side) were in from the bottom. the bolt went through the support arms off the engine, through the rubber engine mount and into a nut fixed to the sub frame so I had to access the bolts from the top. Haynes said go in from the bottom but the mercedes repair CD said from the top.

I removed the hood and then chained across the plates used for engine removal on the heads and lifted on those. (2 at the rear and one above the water pump). I dont know how different the 560 is because of the fuel distributor but everything else should be the same?
cheers
barri

Roncallo · #5 01-25-2008, 07:13 PM

Quote:

Originally Posted by donbryce

I've decided that I'm going ahead with removing the subframe, instead of just replacing the 4 shot mounts, since it doesn't look like much extra work to do so. I read where another member did this, replaced all the mounts, and the whole job was only about 5 hours. I'll probably clean and paint as well.

The shop manual is pretty clear on how this is done, but here's a few things that aren't so clear, which ought to be to anyone who has done this job:

Q1 - To avoid the hassles of brake bleeding, I'm thinking it would be easier to remove the calipers and hang them from the body/wheelwells. The manual addresses uncoupling them, with all the ABS and sensor wires, but this shouldn't be necessary, right?

I suppose.

Q2 - After jack-standing the car, and with a jack under the lower A arm, I should be OK to remove the shock, then lower and remove the A arm jack, leaving the springs in the assembly, as shown in the picture (of another subframe), right?

No the jack stands need to be under the chassi and a jack needs to be under the subframe

Q3 - What is the best way to support the engine before uncoupling the engine shock absorbers and the engine mounts from the subframe?

I have a tool from Northeren Tool for this. I havent used it but it looks good, I was considering using 2 of them for my V12.

Q4 - Related to the previous ?, the manual talks about removing the 'left and right metal shields from the exhaust manifold'. I suspect this is to avoid bending them when using the official 'engine carrying stirrup', true, or is there some other reason? They don't cover anything on my engine except the manifolds....or do they mean the shields over the mounts??

????

John Roncallo

donbryce · #6 01-26-2008, 11:38 AM

Quote:

Originally Posted by Roncallo

I have a tool from Northeren Tool for this. I havent used it but it looks good, I was considering using 2 of them for my V12.
John Roncallo

Is this the engine support from Northern Tools you have? If so, how would it be placed across the engine bay, surely not resting on the fenders (although, with enough padding, and pieces of plywood to spread the load next to the inside edge, I wonder if this would work?)?

I could try using a piece of box tubing with braces welded to the ends, long enough to sit on the unibody 'frame' rails running along the sides, a triangulated set-up similar to the pictured tool.....but it would sure be great to understand how the Mercedes 'engine carrying stirrup' works (part no 107 589 023 61 00, pictured on page/section 33.1-110/2 of the 107 service manual)

truckinik · #7 01-26-2008, 11:44 AM

You need to get in touch with Roncallo. He's the authority on front subframes in the SL cars.

Nick

Roncallo · #8 01-26-2008, 02:38 PM

Quote:

Originally Posted by donbryce

Is this the engine support from Northern Tools you have? If so, how would it be placed across the engine bay, surely not resting on the fenders (although, with enough padding, and pieces of plywood to spread the load next to the inside edge, I wonder if this would work?)?

I could try using a piece of box tubing with braces welded to the ends, long enough to sit on the unibody 'frame' rails running along the sides, a triangulated set-up similar to the pictured tool.....but it would sure be great to understand how the Mercedes 'engine carrying stirrup' works (part no 107 589 023 61 00, pictured on page/section 33.1-110/2 of the 107 service manual)

Thats the one I have. I havent used it for my 107 yet but my plan was to make adapters that could be bolted to the fender attachment bolts. Essentially pieces of angle iron. I also am not sure it is strong enough for my V12 so I might have to use 2 of them. One at the front and one at the rear.

John Roncallo

Richard Wooldridge · #9 02-09-2008, 02:38 AM

When I did mine, I raised the front of the car with the bucket on a tractor and a couple chains, then placed GOOD jackstands under the chassis at the jacking points. Then I placed a jack under the pan (with a wood block against the pan) to hold the engine up. The motor mount bolts had Allen heads and were removed from below. Then I removed the brake calipers and hung them from the sides, as you thought you could do. Then, I removed the swaybar bolts, the shock top nuts and then the subframe bolts, with the tractor's bucket a little bit below the subframe and let it drop into the bucket and backed away from the car. It is easiest to use spring compressors on the springs so you can work on the subframe as an assembly while it's out. The old subframe bushings literally fell out of the subframe, so they were no problem to replace. On my car, I had to replace the subframe with one I got from a 114, so had to drill access holes in the replacement subframe for the motor mount to engine bolts. The mount to subframe bolt locations were the same. When I replaced the subframe in the car, I just put it in the tractor's front bucket, raised it up to the car and bolted it down. No problem at all! Sorry for not responding sooner, I was away for a week or two!
(edited to include the below comments) The picture you have posted shows what I think is an '86 - 89 subframe, as the upper control arms are solid instead of stamped, which is a nice improvement- they are supposed to be stronger. I raised my car a little higher than most people would since it was no effort to do so, so I ended up with the front about 4 feet off the ground, with the rear bumper almost touching the concrete. The engine support bracket looks like it would probably work fine, I welded up one somewhat similar to hold the engine up when I had to replace the transaxle in my sister's caddie, and it worked well. Another point is that I did the job over at my brother's "barn" (read 6500 sq ft shop) with almost every tool known to man onsite, including two metal lathes, milling machine, brake machine, valve machines, 2 hvac machines, distributor machine, tire machines, several 4 gas analysers, 4 post lift, etc ad nauseum. He has spent most of his life collecting cars and tools, so he has not one, not two, but SIX rollaways full of smaller tools. Believe me, it is NICE to have the right tool at your disposal.

donbryce · #10 03-21-2008, 07:29 PM

Thanks for the replies, thought I would post a bit of progress. Richard and Roncallo, you might be interested in my engine support solution.
First off, as pic1 shows, the car is up on jackstands and just far enough out from the wall to allow access to the right wheel area to remove the brake caliper, which I'll do on both sides. In winter, the 2 'babies' have to share the shop space, a single bay garage, so placing the car under the chainfall in the center of the shop to hold the engine up is not an option right now.
Thus, I studied the problem of how to build a support for the engine. I had some 1" x 1" box tubing, and a piece of shelf support channel, so decided to use it. A long piece of heavy wall box tubing would've been better for the cross piece, but I think what I have will work.
Setting it up like it is puts the crossbar directly over the engine support 'eye', with the weight distributed to the left frame rail and the right shock mount plate.
I welded a 1 1/2" long piece of threaded rod to the passenger side upright, and the brace on the driver side, which go through the holes for the upper shock mounts and have a washer/nut to secure them.
The upright on the driver's side rests on the frame, about where the air snorkel fits, and is clamped to the pinch weld flange on the frame rail. The upright on the passenger side rests in the shock mount pocket, and has a tab with one fender bolt holding it laterally.

donbryce · #11 03-21-2008, 07:36 PM

...continuing, a few more pictures. I had already removed the fan, shroud, and radiator to work on the A/C system. The shocks are out, next will be the calipers, which I can suspend with wire from the bolts in the shock mount holes from the engine holder stand, and the torsion bar.

On my SL, there are nuts on the ends of what I presume are the bolts for the engine mounts, running up from the subframe, and they look like they hold the cover plates on top of the mounts. Does anyone know if these must come off first, before undoing the mount bolts from underneath? Edit: To answer my own question, these nuts are part of the engine mounting bracket, and are welded to the plate. They are all the big bolt goes into from the bottom.

donbryce · #12 03-24-2008, 08:23 PM

Subframe is now out. Relatively speaking, with the engine supported, it was too easy. After removing the brake calipers, ABS brake sensors, and the torsion bar:

1. I placed a small 4" X 4" block of wood and a floor jack (those cheap $20.00 ones from the Walmart) under each lower control arm, the wood being just enough to prevent the dust shields from hitting when the subframe drops.
2. I put another jack under the front crossmember of the subframe, giving it a solid 3-point support.
3. I sprayed, and let it sit for a day, each of the 4 bolts with penetrating fluid. I was able to get all of them out with a regular 1/2" drive ratchet and socket.
4. I let each jack down a bit at a time, until the subframe was sitting on the small jack frames. I then manipulated 2 car dollies under the A-arms, so now I can wheel it in and out from under the car to work on it.

As the pics show, all of the underside/sides of the engine are now right there to be cleaned up and worked on. I'll be dropping the oil pan to replace a leaking O-ring on the oil level sender, cleaning up the threads on the exhaust manifold bolts (somehow fastened to the manifolds), and probably re-install the compressor and piping, as well as R&R the starter and alternator connections.

In the last pic, you can see how the 2 rearmost subframe bushings were nearly 1/2" short of their proper height, compared to the front ones and one of the new ones (on the far left). I wonder why the rears only are so worn out?

donbryce · #13 03-25-2008, 07:49 PM

....but a forum member asked me to post some shots of the subframe crossmembers and the control arm mounts so he could compare with his 380SL. I will let the top view of the subframe I originally posted speak for the upper side, as it is identical to mine.
I'm thinking that this would be in reference to the recall for cracking at the control arm mounts, in another thread here.
So I've started cleaning up the frame and attached A-arms, etc., with the worst part being the springs. These are, for some reason, caked in what I call 'junkyard rust', that layered stuff that is easy to get off, but it's all over every part of both springs. My son helped me dig out the sandblaster and what sand I have, so I'll have at it in a few days. Weatherman is calling for more bloody snow tomorrow!

donbryce · #14 04-19-2008, 10:02 AM

The sandblasting and painting went well, and the subframe is back in the car. I used the same 3-point jack method to get it in as I used to drop it down. Easy job with 1 person. The big jackstands are holding up the car, the small ones are for safety in case the subframe falls off one of the 3 jacks (which it did, once). I took the pics after the frame was all the way up into it's perches.
One note on the bushing kit. There are small plastic cone-shaped washers, I think Mercedes calls them buffer stops, that are supposed to be pressed onto the bushings before inserting them in the subframe sockets. They didn't fit on my bushings, due to the small bit of rubber on the outside of the steel casting flange. If you attempt to push them on, they crack. I took a sharp XActo and pared the rubber off so they would fit nicely on the bushings.
I used SylGlyde brake lubricant to slide them in. This stuff won't harm rubber.