Pagoda mystery bolt?

[hands_aus]

Hello,

Lately I have been driving the car a lot, mainly on weekends.

I found this bolt (see pic, dimension of bolt is in inches) on the driveway late this afternoon.
Download Attachment: bolt_3.JPG
28.62 KB

I have two cars..one is a Toyota Corolla, the other is my 250sl.
I don't think it is from the Corolla.

2 years ago I had the rear axle rebuilt. The drive shaft universal joint, drive shaft bearing and flex disk (new bolts) were replaced. I also had the drive shaft re-balanced before it was re-installed.
I was told that they re-balanced it with the new flex disk and new bearing attached.

I supplied new MB parts bought from Caliber Motors, Anaheim USA.

Things I checked...
rear shock absorbers lower bolt... they are both there.
engine mount bolts and they are both there.

This bolt looks like it fits through a bush or something because of the long shaft and short thread.

In the morning, if I have time, I will jack up the front onto my new jack stands and see if I can see the flex coupling.
I will try my mirror and torch technique.

Any advice welcome, thanks

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[Naj ✝︎]

Flex disc bolt?

naj

68 280SL

[ja17]

Hello Bob,

I agree with Naj here. It looks like a flex disc bolt. Do not delay here. You can do a lot of damage to the flex disc, drive shaft and even transn=mission if the situation is left undone!  You'll need to pick up at least one new 19mm head nylock nut (locking nut) and a special washer by the looks of things.

Joe Alexander
Blacklick, Ohio

[bpossel]

Hi Bob,

Flex disk!  See attached pic.
Bob

Download Attachment: flex disk.jpg
31.99 KB

bpossel  (Memphis, TN.)
'71 280SL  /  '97 E320

[hands_aus]

quote:Originally posted by ja17

Hello Bob,

I agree with Naj here. It looks like a flex disc bolt. Do not delay here. You can do a lot of damage to the flex disc, drive shaft and even transn=mission if the situation is left undone!  You'll need to pick up at least one new 19mm head nylock nut (locking nut) and a special washer by the looks of things.

Joe Alexander
Blacklick, Ohio

Hey Guys,
I am an early riser.
Thanks for your feed back and pic.

Joe,
What is 'special' about the washers?
As a temporary fix can I re-use an old washer?
I think I have the old flex disk and bolts etc from the previous axle rebuild.
I understand the need for a new Nylock Nut.

Upon reflection I definitely think you are right.
When I was reversing out of the drive on Tuesday I heard a clunk under the car but I did not worry about it because I thought it was a small branch that had fallen on the ground hitting underneath the car.
I went for a drive of about 20 miles including about 1-2 miles of freeway at about 80km/hr.
I noticed there was some vibration of the internal mirror. Fortunately I didn't travel far.

I can't believe that when installed correctly these nylock nuts only last 2 and a bit years. I wonder if they re-used some of the old hardware?

I gave the MB Tech a brand new MB kit including hardware. Those things cost USD$168.00 (Caliber motors) and AUD$540.00 (MB Qld) 2 years ago so I don't think they will be any cheaper now.

Joe,
Should I replace the flex disk with a new kit just to be sure?

I have very little room in my garage, would I be able to do this job at home or should I have it done by the MB Tech?

Would it be safe to drive it there (about 5Kms) without damaging the auto trans?

I have my jack stands so maybe I can put the front of the car up on those and have a look.

regards

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[waltklatt]

Bob,  How are the brakes on your car?  Any funny noises?
That is also the bolt for the caliper to the axle or front hub.  Depending on which side it comes from.
If the bolt like this comes out then the special metal tabbed washer is broken or missing.  Once the bolt is tightened in place the tab is then bent up to hold it in place.  
Please check your calipers, both front and rears(if you have a later 250SL).
Don't want to see another one of these beauties get crumpled up with a bad brake.
Walter
1967 220SL-diesel

[Ricardo]

Bob
I think Walter might be on to something here...your bolt is not as long as the one's Bob Possel shows and the threads aren't as fine either. Perhaps they changed them over time and you have one of an earlier style? If Walter is right that might explain why you didn't find a nut or washer. I've had caliper bolts get loose and there is usually a metallic clink when the car comes to a complete stop, as the weight shifts off the caliper, but it could be the other caliper bolt is still tight and you might not hear anything. It's possible a loose caliper would cause some vibration at speed too.
Certainly the next thing to look at if the flex disc bolts are all there.

[hands_aus]

Walter and Ricardo,
 
Thanks for your replies.

I checked, the bolt IS from my flex disk.
The other 5 are in place.
This was a new MB part installed in 11/2004.
I have travelled 5814 miles since then.

When they returned the old parts no flex disk bolts or nuts were included, just the old disk. Makes me wonder if they re-used the old bolts and nuts and who ended up with the new ones.

If the new bolts/nuts were torqued to spec I can't understand how this one has come loose in under 6000 miles.

I have just returned from the people who did the original work in 11/2004.
They want to inspect the car for problems before making recommendations.
They are sending a flat top (most likely at my expense) next week to pick it up.

Should I have the flex disk and bolts replaced just in case any damage has been done?
I have only done about 20 miles.

What do you think?

Out of interest I priced the genuine MB parts kit from MB ....... AUD $648.04
They can supply aftermarket at AUD $211.00

I see K&K sell genuine MB for USD $102.00 + freight should work out at about AUD $175.00.

This is our 'Australia Day' long weekend from tomorrow Friday.
Obviously I won't be using my 250sl.

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[mdsalemi]

Bob,

I suspect that I lost one, then more of these same bolts not long after I had transmission work done in 2001; about 300 miles after to be precise.

Everything let loose and I totally lost--and destroyed to the point that there were no salvagable cores--the drive shaft and transmission, and nearly everything associated with these.  The whole system literally exploded, to the point where even the plastic shift insert (it's an automatic) shattered.

The flatbed transport is a good idea.  So is checking and torqueing everything to spec...it is a good thing you found this in your driveway.  My parts were spread around a highway entrance ramp like a crime scene.

BTW those yellow stripes of paint are applied when you torque something.  It isn't Concours decoration.  That's how you don't forget to torque something.

Michael Salemi
1969 280SL
Signal Red w/Black Leather
Restored

[ja17]

Hello Bob,

Since these are shoulder bolts, the nut actually bottoms out on the shoulder during tightening.  This prevents the flex disc from getting squeezed too tight. It the washer is left out or the incorrect thickness is used then the "tightened dimesion" will be different. In other words if the washer is thinnner or not installed the nut and bolt will tighten before the flex disk is snugged up. If too thick a washer is used or too many the flex disc is squeesed too tight or the nut does not bottom out on the shoulder. Look at Bob Possel's Flex disk post. It shows good pictures of the correct installation of the assembly.

There are three long bolts and three short bolts there location is specific and the arrangement of the washers is different on the these.

Joe Alexander
Blacklick, Ohio

[glennard]

You're lucky you found it early!  Bought a 190E once that had the flex disc fail.  Damaged the tranny mount and the mechanic cut the drive torque tube in half with a Sazall.  As dangerous as a plumber!

[ja17]

Hello,

Bob possel's photo below shows correct assembly sequence.

Download Attachment: bflex.jpg
35.89 KB

In addition the early BBB has a good correct illustration of the assembly.

There are some problems with factory documentation here. For some reason my early BBB which is a later reprint shows the later nylock bolt arrangement correctly. My original late BBB shows the early cotter pin arrangement with an additional lock washer on the short bolts!?

Here is the late nyloc style in my early BBB reprint:


Download Attachment: eflex 20.JPG
84.57 KB

Here is the early cotter pin style in my orig. late BBB
Download Attachment: late 10.JPG
79.32 KB

Refer to the dealers parts book which calls for only six washers, one on each bolt.

Here is the dealer diagram in the parts book showing just the different parts and not all the parts.
Download Attachment: parts 1.JPG
53.65 KB

The text in the dealer parts book calls out the quantity  of same parts in the right column.

 Download Attachment: parts 2.JPG
81.84 KB



Joe Alexander
Blacklick, Ohio

[hands_aus]

Hello Joe,

Thanks for your info. I have made a copy of it for my reference.

The people who did the axle rebuild in November 2004 want to inspect the car before doing any work.

I supplied them with a genuine MB kit.

I have only travelled 5800 miles since the work was done.

This bolt should never have come loose if all the original hardware was replaced with the new kit and torqued to spec.

My main worry now is that if one bolt has come loose what are the others like?

Should I insist on a complete replacement with new hardware just for safety sake.

What do you think?

I reckon they will replace the disk and bolts at my expense but I think the job wasn't done properly in the first place.

I remember they were rebuilding the rear axle of a well known heart doctors' 190sl at the same time as they were doing mine.
In fact they asked me to GIVE them my old Right Hand rear self- aligning wheel bearing (replacement cost me USD $109.00) because they didn't have time to order the correct one up from Melbourne before the owner wanted to drive to Sydney then across to the Adelaide Classic rally (were you there?) on my old bearing.
This was a job that didn't need to be done on my car.

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[George Davis]

Bob,

I had a driveshaft get chewed up from reused flex disk bolts and nuts coming loose.  I'm probably over-cautious, but I never reuse the bolts and nuts now - which means replacing the flex disk and hardware any time I have to take it out, which I've done more than once.  Not cheap, but cheaper than a driveshaft.  I hope you don't need anything more than a new flex disk.

George Davis
'69 280 SL Euro manual

[hands_aus]

Resolution:-

The manager of the MB Service Company called this morning and said that after inspecting the flex disk they found the washers on the 3 bolts (flex disk to transmission) were installed incorrectly.

Apparently the washers were placed under the nut and not under the head of the bolt.
He showed, on the removed nuts, where the bolt had not gone all the way through the nut. This allowed the nut to work loose.

He also said that the other 2 bolt/nuts were loose.

Potentially a serious problem!

From a safety point of view, I asked them to supply and install a new disk kit at their expense.

They refused, but said they would install one if I paid for it.

They recommended I re-use the existing flex disk with new nuts and washers.

The manager almost guaranteed me that the exisitng flex disk is ok.
He intends giving me a letter stating what had happened and what action was taken to resolve the situation.

He personally had taken the car for a test drive and said he could feel no vibration.

So I have gone with their recommendation.

They did not charge me for any labour or the new nuts and washers or the freight charge to get the car to their workshop.

I drove the car home (5 Km) and the car was back to normal.
 
I asked the manager if he was going to instigate a refresher training program, given this won't be the first flex disk they have installed.

Will I use this company again? I am not sure.
I am pleased that I have had lots of the BIG jobs done so that in the future I will not be too dependent on them.


Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto