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  #1  
Old 01-11-2002, 04:54 PM
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Question Lug holes: retap or helicoil? (1975 300D)

Hey folks -- picked up a 1975 300D to use as a winter car yesterday, and I see that three of the five (!) lug holes are stripped or otherwise useless on the left rear wheel. (In other words, I have TWO LUG NUTS holding that wheel on right now! Needless to say, I'm not driving it at the moment).

Has anyone had any luck re-tapping the threads on these rotors while they are still on the car? Anytime I try to start a new lug bolt, it tears up the threads and won't hold. I'm guessing I'll probably need to try to take the rotor off and into a machine shop to have it done... bummer, as I'l going to bet that the calipers are rusted on there pretty solid. Guess I'll need to free them up for any future brake jobs anyway.


Frustrating, as this car runs quite well otherwise, and I'd love to be driving it right now!

Thanks in advance for any advice you can offer,

Chris
cscmc1@eiu.edu
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  #2  
Old 01-11-2002, 05:14 PM
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By all means, run a tap through the three holes. Youv'e got nothing to loose and much to gain.
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Michael LaFleur

'05 E320 CDI - 86,000 miles
'86 300SDL - 360,000 miles
'85 300SD - 150,000 miles (sold)
'89 190D - 120,000 miles (sold)
'85 300SD - 317,000 miles (sold)
'98 ML320 - 270,000 miles (sold)
'75 300D - 170,000 miles (sold)
'83 Harley Davidson FLTC (Broken again) :-(
'61 Plymouth Valiant - 60k mikes
2004 Papillon (Oliver)
2005 Tzitzu (Griffon)
2009 Welsh Corgi (Buba)

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  #3  
Old 01-11-2002, 10:29 PM
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I'm just going to buy new rotors....the tire shop goobered mine up for good, they were torqued on to 1000 ft/lbs when I bought mine.
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83 SD 143 K miles
93 Grand Caravan 130K miles
92 Buick Regal (winter car)
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  #4  
Old 01-12-2002, 08:56 AM
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Yes, the fricking morons at the tire stores can put on 8 and one half billion pounds of torque on these lug bolts. AND they don't do it in a star pattern, just go around in a circle!!

Please don't do this!!!

Here is what you do.

Loosen all the bolts before jacking up the car. You will need a 40 foot cheater bar. :p Please note, I said loosen. Just enough so you can easily turn it with a socket wrench with a 17mm socket or lug wrench. Then snug it back in so there is no play. Remember, all the weight of the car is still on the tire.
Loosen them in a star pattern please.

Then jack up the car, lifting the tire off the ground. Take them all off. Get yourself some copper grease. This is sold at NAPA stores and is known as 3M anti seize or brake grease. There is an aluminum one and a copper one. Ask for the copper one.

Take each bolt to the wire wheel on your bench grinder. (everyone has one, right?) or use a wire brush, or some solvent and an old tootbrush. Clean the threads.
Brush some on to the threads of the bolts with the handy-dandy brush which is attached to the lid of the can. You don't need a lot, just coat the threads.
Also, on the back of the wheel where it contacts the rotor hub, put some smear on the points where it makes contact. You will probably be able to tell where that is by the dirt marks.
This will make the wheel not weld itself to the hub, due to road salt, etc.

Re-mount the wheel. If you have trouble starting the first bolt, join the club! It helps if you don't jack the tire too far off the ground in the first place. You can use the lug wrench as a lever under the bottom of the tire too.

Run in all the bolts with your fingers now. You can do this now with the grease! Next, snug all bolts up in a star pattern, just snug so as be certain all things are aligned. Next, torque all bolts in two stages in a star pattern to specs. What is that, 60 lbs? I forget. You will be surprised, it is not that much. It is easily achieved with the lug wrench and moderate pressure. Mounting alloy wheels is different than your old mans 58 chevy with steel wheels and drum brakes.

Why the star pattern? Because you can easily put a slight warp on the brake rotors if you don't. This may not be an issue with rotors which float on a hub, but is an issue with integral hubs.

And if you have steel wheels on your old MB, you will be rewarded with a better ride if you switch to alloys because they are much lighter.

OK
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Ed
1981 300CD (Benzina)
1968 250 S (Gina) 266,000 miles!
1983 Alfa Romeo GTV6 (Guido)
1976 Jaguar XJS-saved a V-12 from the chevy curse, what a great engine!
1988 Cadillac Eldorado (better car than you might think!)
1988 Yamaha Venture (better than a Wing!)
1977 Suzuki GS750B
1976 Yamaha XS 650 (sold)
1991 Suzuki GSX1100G (Shafty Gixser)
1981 Yamaha VX920RH (Euro "Virago")
Solex Moped
1975 Dodge P/U camper


"Time spent in the company of a cat, a beer, and this forum, is not time wasted!"
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  #5  
Old 01-12-2002, 01:09 PM
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What a pain in the butt!

I'd TRY running a tap in the holes, but my suspicion is that the threads are buggered from using the wrong bolts, leaving them loose, or grossly overtightening them.

The real (and safe!) solution is to replace the hub. Bigger pain in the butt. The hub is held on by a retaining ring on the inner side of the rear control arm, requires a spanner to remove.

You will need to pull the axle half, the remove the retainer and pull the hub out, should just sit on the bearings. I'd get new seals, too, just out of paranoia.

There are two different hubs/axle combinations -- one uses a larger bolt that the other, and the torque requirements are different. Make sure you get the correct one, although the hub may be the same.

Please don't drive with only two lug bolts on the wheel!

Peter
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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!
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  #6  
Old 01-13-2002, 10:01 AM
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I don't know how many miles are on the car, but if you do have to replace the hub as psfred suggest you may have to do (This is why I would first try running a tap), I would consider replacing the wheel bearing. You have to remove the hub to do this anyway.

I have a replacement bearing to put in myself. I'm not looking forward to the job.
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Michael LaFleur

'05 E320 CDI - 86,000 miles
'86 300SDL - 360,000 miles
'85 300SD - 150,000 miles (sold)
'89 190D - 120,000 miles (sold)
'85 300SD - 317,000 miles (sold)
'98 ML320 - 270,000 miles (sold)
'75 300D - 170,000 miles (sold)
'83 Harley Davidson FLTC (Broken again) :-(
'61 Plymouth Valiant - 60k mikes
2004 Papillon (Oliver)
2005 Tzitzu (Griffon)
2009 Welsh Corgi (Buba)

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  #7  
Old 01-13-2002, 01:00 PM
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Since we're on the topic of bearings, I have a question. I noticed that when I spin the front tires of my 300SD, the wheel spins about 4 times--that's with pads removed from the calipers. I didn't hear any funny noises from the bearings. I have a small amount of end-play on the hubs. In contrast, in my Pontiacs with front wheel drive, the rear wheels spin at least 20 times (I lost count). Is this normal for MB wheels to free spin four times since the 300SD is such a heavy car?
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  #8  
Old 01-13-2002, 05:25 PM
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The Pontiac uses a permanently sealed double race ball bearing type bearing. The MB uses a tapered roller bearing packed with high melting point grease. There is a little more rolling resistance with the double taper roller bearing, so the wheel won't spin as long.

You should have just palpable play -- too little for a distinct "thump" when you pull the wheel straight out and push straight back in. To set the clearance, take the hub cover off with a large pair of channellocks, loosen the locking screw, turn the nut in until the wheel turns only with considerable resistance (don't tighten the nut down untill the wheel is really hard to turn!), then back off 1/3 turn on the nut and tighten the locking screw. Re-install the hub cover with a driver on the lip -- DO NOT drive it on by thumping the center with a mallet or hammer -- this will cause the outer part to bulge and draw the opening closed, so that it won't stay tight anymore. Sounds counter intuitive, but banging on the center makes them loose every time.

The nice thing about the GM bearings is that they are all the same on all four wheels, held on by four bolts. Easy to change, not adjustable (so the can't be adjusted wrong), last many many miles, have the spline for the front drive axle, so one bearing fits both front and read. The bad thing is that they cost about $90 each, last time I bought one!

Peter
__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!
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  #9  
Old 01-13-2002, 06:20 PM
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roters are cheap.
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  #10  
Old 01-13-2002, 08:57 PM
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psfred,

Thanks for pointing out the different between Pontiac bearings and MB bearings. I had a Jeep that had tapered roller bearings and those wheels spun much more freely than the ones on the MB. But, do you guys think that wheels should free spin more than 4 times with a moderately good spin? Remember with this with out the brake pads installed.
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  #11  
Old 01-14-2002, 10:40 AM
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The bearing I just bought for the 190E was $78. It said 'kit' so I thought I was getting two. I couldn't believe it was only one.

Now I have to make sure I replace the correct one.
The bearing whine I have goes away when cornering to the right, so I believe that it is the right bearing I need to replace as the bearing is unloading during the cornering.
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Michael LaFleur

'05 E320 CDI - 86,000 miles
'86 300SDL - 360,000 miles
'85 300SD - 150,000 miles (sold)
'89 190D - 120,000 miles (sold)
'85 300SD - 317,000 miles (sold)
'98 ML320 - 270,000 miles (sold)
'75 300D - 170,000 miles (sold)
'83 Harley Davidson FLTC (Broken again) :-(
'61 Plymouth Valiant - 60k mikes
2004 Papillon (Oliver)
2005 Tzitzu (Griffon)
2009 Welsh Corgi (Buba)

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  #12  
Old 01-14-2002, 08:46 PM
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Since we're on the subject...

This "lug bolt" concept is new to me with the MB. I've done brake rotor/caliper replacement, but that was a while ago, on a GM.

I've seen a front brake "kit" on E-bay, which includes pads, rotors, sensors, a few pins and rotors for my SD.

My question, before I pull the wheel apart, is: Is the rotor what I'm bolting the wheel onto, or is the rotor floating on some other part? It looks like, from pictures I've seen, is that the rotor is what the bolts to into.

Thanks in advance...
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93 Grand Caravan 130K miles
92 Buick Regal (winter car)
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  #13  
Old 01-14-2002, 11:31 PM
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MB rotors typically bolt onto the back of the outer flange on the front hub. You will need an impact wrench, probably, to get them off. The hub (and bearings) must come off the get to the bolts. At least, I've never found a way to get them out with the hub on the car.

The wheel bolts to the hub.

Plan on cleaning and repacking the bearings when you do the rotors -- there is no way to get the rotor off that won't get dirt into the grease.

Not a big job, generally, but the rotor to hub bolts will be TIGHT.

Peter
__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!
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  #14  
Old 01-15-2002, 09:12 AM
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Mercedes Man,

Tapered roller bearings should be snug without any play, when you rock the bearing with the road wheel attached.

The reason your jeep, or other cars with similar bearings spin longer is probably due to the fact they don't have this ultra cool nut to tighten the bearing. On other cars you have to choose a hole for the cotter pin, and it always is a compromise as to pre load on the bearing.

Hope this makes sense...
__________________
Ed
1981 300CD (Benzina)
1968 250 S (Gina) 266,000 miles!
1983 Alfa Romeo GTV6 (Guido)
1976 Jaguar XJS-saved a V-12 from the chevy curse, what a great engine!
1988 Cadillac Eldorado (better car than you might think!)
1988 Yamaha Venture (better than a Wing!)
1977 Suzuki GS750B
1976 Yamaha XS 650 (sold)
1991 Suzuki GSX1100G (Shafty Gixser)
1981 Yamaha VX920RH (Euro "Virago")
Solex Moped
1975 Dodge P/U camper


"Time spent in the company of a cat, a beer, and this forum, is not time wasted!"
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  #15  
Old 01-15-2002, 11:01 AM
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Running a tap thru stripped threads will do no good because the threads are gone and there is no way to restore them other than a helicoil. Because the rear spindle is so difficult to replace, I would try using a helicoils. But I wouldn't use a helicoil on the front spindle because that is so easy to replace.

P E H
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