Flex disc help PLEASE - PeachParts Mercedes-Benz Forum

kpb · #1 12-19-2003, 01:16 PM

Excitedly crawled under my '72 280SE 4.5 an hour ago to work on tranny mount and flex disc. I believe I have reviewed all the pertinent posts in other threads but still have a bit of a problem.

Tranny mount removal no problem at all, just as the experts here said it would be. HOWEVER, for the flex disc, loosening the clamp at the center bearing is a bear. Channel locks have proven useless and I see where other folks have apparently used a pipe wrench or "chain" wrench. OK, I'll go tool shopping today, but must I lower the exhaust also? The space for leverage is minimal and I am laying on my back under jackstands so I'm not in the most spacious situation. I got the parking brake cable out of the way but cannot gain more space unless I drop the exhaust. I do not relish the idea of trying to get those pipes apart at the junction nearby, they look original.

Moreover, I assume the front hexagonal fitting/nut (the smaller one) on the driveshaft is the one I attack rather than the larger, rear-most one??

Finally, is there a method by which to fit the new disc in place without pulling the front piece of the driveshaft back? Can I not just remove the old tattered disc and squish the new one into place?? I know this would be a very tight squeeze but can it be done?? It seems the metal sleeves in the new disc will not be susceptible to squishing into place, right?

As always, your grateful student...

ctaylor738 · #2 12-19-2003, 01:47 PM

I am NOT a 4.5 person, but is it possible to undo the rear flex disc, drive the sleeves back, and move the flex disc over to clear the flange so that the whole driveshaft can move back?

kpb · #3 12-19-2003, 01:59 PM

thanx for the idea. the rear is a u-joint. suppose I could drop it there and try moving the whole shaft a bit. I tried to private message psfred cuz i see he's here but, I suppose being the techno-clod I am, he did not get the pm or some other such ill befell the effort. Ii wanna get this put together and DRIVE!

psfred · #4 12-19-2003, 02:45 PM

kpb:

I'm at work, I usually don't check the pm's much...

Two pipe wrenches will get the driveshaft nut loose -- get big ones, it's large.

To lower the exhaust, you need only support it and remove the rubber loops -- one at the pipe to front muffler connection (large, goes up across both pipes) and four on the rear muffler. The whole exhaust will then droop down.

You will also need to drop the center driveshaft support bearing if you have one, otherwise the driveshaft won't pull back far enough.

Peter

JoeyTheB · #5 12-19-2003, 06:14 PM

Ok, it wasn't easy - definitely consider bolting it up right now and taking it over to the local shop.

My exhaust was dropped at front (disconnected at ex manifold) already - still connected at rear.

Nut - you want to loosen the rear nut - front is part of driveshaft.
And it is normally threaded.

Tools/Procedure for nut -
PB Blaster (walmart under 5$)
Chain Pipe Wrench (Sears 27$ or rent from HD/Lowes)
1 ft cheater pipe
Reg Pipe Wrench (on hand).
Old Carpet to lie on

Remove spash gaurd and center bearing support.
Raise rear on jack stand so at least one wheel is free.
Soak the nut w/PB Blaster from all angles, and lightly tap
each flat face of nut with a hammer to "warm it up".
Have a beverage and go soak nut again.

Attach reg/std pipe as a backup wrench to
fwd/round section of driveshaft
Be careful not to bite onto section with weights !

Put the chain Pipe wrench on the nut - I used a 1 ft cheater pipe.
Get it in position, make it bite, and put some muscle into it.

Loosen the nut all the way, then slide the fwd section
"into" the rear section. Hopefully, you can get enough room to clear the fwd section from the shaft coming out of transmission that you can't see. Otherwise, you're going to have to drop the driveshaft like me.

By the way, I tried to change the center bearing with the drive shaft in place - it was much easier to just remove the whole thing and work on it outside the car.

NOTE: Once the car is back together again manual calls for rolling the car back and forth before tightening up the nut.

Let us know how it works out,
Joe

JoeyTheB · #6 12-19-2003, 06:17 PM

Safety Glasses !

kpb · #7 12-19-2003, 07:06 PM

Hey Joe -- awesome. I knew you had that thread going a while back but this new info is exactly what I am seeking. Just crawled out from under the beast and was fiddlin' around and took four of the six attaching bolts off the flex disc. I borrowed some wrenches from a buddy mechanic but they are not big enuf. Of course, I was also trying to loosen the front "nut" which apparently is not a nut!! The wrench will fit that but I'll need to find one of those chain wrenchamajiggers to get on the bigger piece toward the rear. I was thinking that maybe when I drop the center bearing mount I would gain enuf leeway to be able to pull the disc out but that sounds improbable given your experience.

Whatever... I'll call it a night now that I know what I'm in for. Get the right tools, attack again soon (not tomorrow, dangit!) Your tip re: bolting it up and going to the local shop...HHMMMM, well the local guy (tool-lender) could probably get to it in four to six weeks and he has never seen one of these before. Closest reputable shop I have found is 30 mis. away and this car will NOT drive the way it is, my disc is virtually in pieces.

Thanx again for willingly sharing your recent experience so that I may suffer less than you...

JoeyTheB · #8 12-19-2003, 10:04 PM

Keep at it k !

I think you'll have room to get the wrench on the nut once the center bearing is loose. And according to others, you should have enough room to get the front half off.
Maybe tap/pry it back a little -
I never bothered b/c mine was loose from rear by that time.

And sorry 'bout the shop comment - I keep threatening myself with that, but haven't done it in years. Besides, you don't want people who don't know that car working on it. Been there, done that.

kpb · #9 12-21-2003, 02:52 PM

Thanx to excellent guidance, I am to the point on my flex disc where I have the front shaft as loose as it gets, nut is all the way off the threads and still I do not have enuf room to drop the shft off the tranny shaft. DAMMIT. What am I missing?

Joe, if I gotta drop the driveline at the rear universival, how do I do that?? I do not see any of the typical clips holding the u-joint in place, y'know the ones like sanp rings with holes in em to squeeze togeth for release.

I am very weary of lying on the garage floor in winter doing this. Your help is appreciated...

Mark DiSilvestro · #10 12-21-2003, 04:52 PM

You shouldn't need to take the clamp-nut all ythe way off to collapse the sliding joint. If it's all the way off, it may actually prevent you from fully collapsing the joint. You may need to screw the nut partly back on to provide more collapse space. If, after fully collapsing the joint, you can't drop the center bearing low enough because of interference from the brake cable and exhaust, you'll need to disconnect the driveshaft at the differential. The 'U' joints aren't clipped in but are permanently pressed in and peened in place at the factory. You'll need to unbolt the rear end of the driveshaft from the differential.

Happy Motoring, Mark

JoeyTheB · #11 12-21-2003, 05:15 PM

Sorry you had to do this - I was hoping you could get by without dropping shaft. Hey, at least you have a garage floor - mine work area is gravel, under a carport.

I loosened nuts, not u-joints.

Like Mark says, the nuts are held in place by a metal clip that must be "peened" back. The lip is bent around the nut so the nut won't move.

You can bend them back with a screwdriver so they are flat, then attack with your 17mm box end and a big flat-blade screw driver wedged in the ujoint as backup.

If you are actually dropping the driveshaft, you may have to remove the emergency brake spring bracket like I did.
If it gets to that, turn the adjusting nut until the spring is loose,
remove one of the two bolts holding the bracket in place,
and you should have enough room to clear.

Good luck,
Joe

kpb · #12 12-21-2003, 08:06 PM

Thanx fellas. After I posted my plea I went back out and figured out what Mark was saying about the nut. I think I was restricting my available movement. Ended up prying the front shaft back further with a big honkin' open-end wrench... before, I was trying to simply slide it back with hand-power. Anyway, bottom line at this point, new flex disc is ON!!

Now, what I presumed would be easy -- the tranny mount. Because my old one was pretty-well collapsed, new one does not wish to fit into place and minimal prying so far has not helped. I think the only restriction at this point are the exhaust pipes. Sorta hate to drop them from the manifold if I don't have to because of breaking bolts, unknown gaskets, etc. Any ideas?? I'm anticipating tomorrow using a wood buffer and cranking the (borrowed) floor jack under the tranny to see if I can gain the needed 3/4" clearance. Also, I found an aluminum plate, like a filler, under the old mount -- I suppose it is prudent to use this item under the new?? It is about 1/8" thick. Any pertinent experiences?? Thank you.

psfred · #13 12-21-2003, 08:12 PM

Drop the crossmember, don't mess about trying to stuff it in, it ain't gonna go. Easy, just four bolts.

Make sure you put it in right way round -- there is a notch or a pair of bumps on the top that match up with the tranny housing for location.

Peter

kpb · #14 12-21-2003, 08:47 PM

I have the crossmember out and floating free!! I have yet to discern a method to push the mount into place with the crossmember relatively restricted by the exhaust pipes.

As always, your gracious patience is gratitudinaly appreciated...

JoeyTheB · #15 12-21-2003, 09:34 PM

With a piece of wood and a scissor jack.

I had to raise the tranny to make the cross member fit,
even with exhaust pipes dropped.

Metal plate will go in fine when you get the tranny jacked.

Good you got your flex disc in !