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Premium Member
1983 380 SL
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2,631 Posts
Discussion Starter #281
Would something like this work? We're Sorry
Almost, but not quite.

What I need is a counter bore for a TimeSert insert and not a counter bore for a standard 10 mm bolt. The cutter size of the counter bore is larger in relation to the size of the pilot than a standard counter bore by approximately the thickness of the wall of the TimeSert itself.

However, I believe I found the solution... I need a counter bore with interchangeable pilots. I went to the Global Industrial web site and ordered a 1/2" 3 flute counter bore and 2 interchangeable pilots, a 3/8" (.375) and a 13/32 (.406). The pilot in the counter bore supplied with the TimeSert kit measures .402 and it fits into the tapped holes with a little bit (very little bit) of play so I figure a .406 will fit better. I ordered the 3/8 (375) just in case the 13/32 is a bit too big. If one doesn't work the other one will.

So this will solve my 4 mm recess below the surface problem. I can counter bore as far as I need with the counter bore I ordered because it doesn't have a built-in stop. It will keep counter boring as long as I keep pressing it into the hole. Inasmuch as all I need is to increase the counter bore depth by 2 to 3 mm, a light pressure is all that is needed. I'll probably wrap some tape around the flutes of the counter bore at the 5 mm mark.

I also may have figured out why Mercedes wants the threads to start at least 4 mm below flush. It was actually AlterSchinken who filled in the missing information when he said (I think it was him) that 70% of the clamping force is exerted on the first 3 or 4 threads. At first I was thinking "so what" you'd still have to distort the metal for that to be a problem and how likely is that to happen?

Well, it's probably not likely for that to happen but it's not impossible either... and why? Because if you don't counter bore the threads then the first 3 or 4 threads will be sitting in the first 5/32 of the block metal but by starting the threads 4 mm below the surface you are spreading that 70% of force over twice the thickness of metal. Twice the metal is twice as strong (I guessed at that but it's stronger for sure).

Of course I'm only guessing that's why they counter bore 4 mm into the block... not because there is concern for the non-threaded portion of the bolt to bottom against the insert and not because the insert might pull up and bottom against the head... but for the simple reason that it gets twice as much metal to resist the force of not only the clamp pressure of the torque on the head bolts but the constant pressure of 4 explosions going off thousands of times a minute. Again... all guess work on my part
 

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Registered
1998 C280; 1987 560SL
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492 Posts
That assumes that my windows work. :)
Seriously... I don't drive the car in the rain and it is always garaged, but in making room for the engine rebuild I pushed the car outside. With the engine & tranny removed the front of the car sits high which probably contributed to the water gathering mostly behind the seats. It's dry in there now, except for the carpets... is there any harm in my leaving the drains I fabricated in place? Also, where are the drain lines from the heater box? Are they accessible from under the dash or inside the engine compartment?

Thanks
The heater box drain lines are accessible from the inside by removing the under dash panels on either side. I believe there are two drains on each side (at least on the 560). The tubes are thin rubber material and a couple of mine were in bad shape. I replaced them with some hose I had laying around that was about the right size while I had the lower heater box out repairing the vent pods. They hook to the heater box and run through the transmission tunnel. You can see them underneath the car beside the transmission. They are about 5/8" to 3/4" in diameter and they also have a duckbill end that acts like a check valve to allow water out but keep bugs and debris out. I can't remember how good the access is with the center console in the car, but I believe it is accessible. Here are some pictures of the heater box and one picture shows one of the drain hoses.

 

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Outstanding Contributor , Bob's Your Uncle!
-----'83 280 SL----- 5 speed....The PIG
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29,338 Posts
Rome wasn't built in a day.

Epic as THAT was.......you will soon have your own Wikipedia entry.
 

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Premium Member
1983 380 SL
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2,631 Posts
Discussion Starter #284
I received the new counter bore today... Global ships fast.

Here's a photo of the new counter bore with the .406 pilot partially inserted. I didn't insert it all the way so you could see that it is changeable. It's held in by a set screw (not shown).
The .406 counter bore fits the tapped hole perfectly... no detectable play at all and it slips right in. The .500 width of the counter bore matches the original pretty close.

Notice that the counter bore itself has no stops on it so it can counter bore to any depth you need.
Those head bolt threads are going to start 4 mm below surface after all. (y)

MercPilotCounterBore.jpg
 

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Premium Member
1983 380 SL
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2,631 Posts
Discussion Starter #285
Counter Bore all set with tape at the 5 mm mark. The set screw used to hold the pilot in was 1/16th and I didn't have one that small. A quick trip to HD and the pilot was finally tightened in the counter bore.

I'll post some pictures after the TimeSerts are installed.

MercCounterBoreSet.jpg
 

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Registered
1987 560 SL, 1990 300E 4Matic
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506 Posts
Just thinking, for all the trouble you've gone through in order to get everything just right, do you think that a set of reasonably priced stops might be a better way to go for your counter bores than tape?


2623065
276.jpg
 

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Premium Member
1983 380 SL
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2,631 Posts
Discussion Starter #287
Just thinking, for all the trouble you've gone through in order to get everything just right, do you think that a set of reasonably priced stops might be a better way to go for your counter bores than tape?


View attachment 2623065 View attachment 2623065
Ordinarily I would say yes but a hard stop could scratch the surface of the head and besides, as it turns out I paid very little attention to the tape. All it took to increase the counter bore from 3mm to 5mm was a light pressure on the drill for about 1/2 second... maybe less. Really just one push and it was done. I increased the depth of the counter bores on an entire side in a minute of two... maybe 3.
 

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Premium Member
1983 380 SL
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2,631 Posts
Discussion Starter #288
Well... the TimeSerts are in. What a PITA job... but like others before me have said, now that I did it I'm glad I did.

I managed to get the 4mm recess on 35 of the 36 head bolt holes. One stopped at just under 3 mm. I'll consider if I want to remove it and re-counter bore the hole 1 mm deeper. I don't know how I missed it but I obviously did. According to TimeSert videos it's real easy to remove a TimeSert using an easy-out. We'll see... I might just leave it.

One interesting note: Using the prescribed 24.5 mm TimeSerts coupled with counter boring the hole by 5 mm (to allow for the 1 mm shoulder on the TimeSert) the TimeSert installation tool bottoms out in the hole only one turn of the tool after it finishes setting the TimeSert. That's cutting it awfully close.

And one more thing... I had to re-tap all 36 holes (after I removed the drill fixture), by an additional 1/2". The tap TimeSert supplies in the kit is too short to tap the hole to the required depth with the drill fixture in place. Your knuckles hit the screw heads that hold the drill and tap bushings in place. Once I removed the drill fixture it was obvious that the holes weren't tapped deep enough.

MercTimeSert1.jpg
 

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Premium Member
1983 380 SL
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2,631 Posts
Discussion Starter #289
Got a notice from Autohauz today... they only have 4 sets of rings and their supplier has them on backorder with no specified restock date. They refunded half my money.
Now I have to find another supply of the same part with the same part number. Bah!
 

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Outstanding Contributor , Bob's Your Uncle!
-----'83 280 SL----- 5 speed....The PIG
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29,338 Posts
Got a notice from Autohauz today... they only have 4 sets of rings and their supplier has them on backorder with no specified restock date. They refunded half my money.
Now I have to find another supply of the same part with the same part number. Bah!
Holy fuck. I am sympathizing at the same time thankful it's you. And not me. I'd be in full "I'M GOING TO KILL YOU" mode.
Not a good look for The NOB.
 

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Outstanding Contributor , Bob's Your Uncle!
-----'83 280 SL----- 5 speed....The PIG
Joined
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29,338 Posts
Holy fuck. I am sympathizing at the same time thankful it's you. And not me. I'd be in full "I'M GOING TO KILL YOU" mode.
Not a good look for The NOB.
But.....Good luck! :)
 

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Premium Member
1983 380 SL
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2,631 Posts
Discussion Starter #292
Holy fuck. I am sympathizing at the same time thankful it's you. And not me. I'd be in full "I'M GOING TO KILL YOU" mode.
Not a good look for The NOB.
At this point I take everything in stride. I'm pretty sure I'll find another supplier... it's just that I was hoping to start putting this beast back together but not having the rings might put a damper on my plans. :unsure:
 

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Registered
1987 560 SL, 1990 300E 4Matic
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506 Posts
At this point I take everything in stride.
It's good that you have that "no worries" attitude. As you said, there are other venders. The good thing is that you still have plenty of lead time before top down summer driving season starts. Your saga will all be worth it in the end.
 

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Premium Member
1983 380 SL
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2,631 Posts
Discussion Starter #294
You're right... now if I could just remember where everything goes and in what order....
 

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Premium Member
1983 380 SL
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2,631 Posts
Discussion Starter #297
Uh oh!... I just got this message from the eBay seller of the rings...

We regret to inform you that the item you have purchased is unexpectedly out of stock and a date when this particular inventory will be replenished is unforeseeable at the moment. Your order has been refunded and we are working to eliminate issues like this from happening in the future.
We apologize for the inconvenience and we thank you for your understanding.
 

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Premium Member
1983 380 SL
Joined
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2,631 Posts
Discussion Starter #298
Holy crap... these rings are out of stock everywhere with no restock information available.

Damn. :mad:
 

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R/C107 Moderator
1986 560SL: '84 500SL: '84 280SL 5 speed: other 107s
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32,162 Posts
Are you searching by part number? I think it is A 001 030 79 24 for standard.
 
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