High Speed Driving 300E
 

I have had the opportunity to take my '91 300E 3.0 up to the 130mph range a couple of times on a safe track area but get some vibration that I can't tell if it is wheel balance or suspension components. At 75-85 it's very smooth. I have about 40K on new tires now so wondering if I should rotate and balance. What other components do I need to check and how? I have new struts and shocks all around. Seems like it could be rock solid!!!

Thanks,

sptt

What are your tires speed rated for? :)

What tire pressure were you running?

Oh...good question John! I don't know but will find out! Seems like it runs super smooth anywhere from 75mph tp 85mph. I didn't even think about that but I do have the pressure at about 5psi below max (I think they're 45psi rated).

Trying to Interpolate
 

the Tire pressure you're running...

Are you saying the tires are a Max PSI rated @ 45...
AND you're running them @ 40 PSI?

If so MUCH, MUCH TOO MUCH PSI !

See the Tire Inflation Placard on the Inside of the Fuel Fill Door.
It has a Proper Inflation Pressure for High Speed Operation.

You'd better be running At Least H rated skins at that speed.

(Also,take into account the increased heat/pressure from High Speed operation.)

If he is running performance low profile tires, 40psi is normal.

Stock size tires shouldn't be running at 40psi.

Also, how often are you doing the R&B with those things?

I wouldn't attempt any land-speed records (personal!) if I hadn't just had the tires rotated, balanced and checked over for ANY SIDEWAY/TREAD issues at all. And, how'd the last alignment go for you? Everything in spec.?

130MPH? GPS co-ordinated and confirmed?

And...when did you check those inflation numbers? When the tires were cold, not driven on yet for the day?

Your tires should be R&B at least every 7,500 miles...minimum. And there IS a difference when it's done correctly...you can feel it.

Do the R&B before you spend money on anything else...unless you like having less weight in your wallet. :rolleyes:

... I would not be going on any top end sprees with a driveline vibration present at lower speeds. It is only going to become worse the faster you go...

Inspect the flex discs too.

How are your tyres new when they have 40000 miles on them? :confused:

Unless you have fairly new H, V or Z rated tires, balanced and rotated, let us know what day and what freeway you will be on here in SO CAL so I may stay safely in my garage.:eek:
Anziani
'93 300CE 196K
'95 E420 122K

is the vibration comming from the front of the car or rear? does it vibrate wen you accelerate? does it vibrate when you coast?

Just an FYI - If your going to be doing high speeds for an extended period of time, raise your tire pressures 6-8 psi.

Thanks guys. I'm going to have the tires rotatated and balanced again. I think it has been over 7500 miles since the last time I had this done. I don't plan on driving that fast again but was wondering if something in the suspension that looks and feels ok could cause the vibration. Both flex discs are newer and in good shape, and front is the correct flex disc as well as the back. I will deflate the tires to the recommended 27/27 psi that the fuel door shows. Wow! I never knew that label was there. I'm glad I asked! I filled the tires with air after driving and in hot weather conditions but could not find the inflation recommendation anywhere before. These babies are probably way too tight!!! Duhhh! The suspension is nice and stiff and turns are very tight with little to no play in the steering wheel.

Please do yourself (and everybody else you put at risk) a huge favor and learn about tires.

You don't know when your last rotation/balance was, you don't know how to check your tire pressure, you don't know what your tire pressure should be, you don't know the speed rating of your tires, you consider them "new" at 40k miles, and you're taking the car to a claimed 130 mph.

Way too many damned important "details" being ignored in this scenario.

Ramonajim...Wow! That was pretty harsh. I hope you feel good about that lashing you just gave me. If you knew me you wouldn't have done that. Most of these guys are very helpful in this forum. Maybe I'm an idiot here on this one but at least I'm trying to find out and do the right thing. If you read my first thread correctly, I said I was on a safe track and that the tires were new and now have 40K on them. Have a great day. You seem like a sharp, wonderful individual yourself ;)

Meh. This went 130mph back in 1909. (On wooden spoke wheels). Leave the poor guy alone. ;)

http://4to40.com/images/earth/scienc...ey_steamer.gif

Thanks John! Lol!

sptt, tire inflation pressure information is also on the driver's door jamb and in the Owner's Manual. You can regularly run your tires at up to 34psi without any problems ... 27psi gives a very cushy ride.

Thanks Ferdman! I don't have anything in my door jambs as that is where I first looked and it did not come with an owner's manual. It does have the sticker in the gas tank door but I just learned that today. Cushy ride is what I am after! I already deflated to 27psi and am going to get the rotation and balance done. You cannot see any visible wear on the tires...they look so even compared to my son's new Nissan Truck and my wife's Altima SER (those tires go way too fast!).

Tire Care (From the Experts)
 

http://www.michelinman.com/tire-care/

Improperly Inflated Tires are Invisibly Damaged by the Improper PSI.
(AND MAY FAIL WITHOUT WARNING,DURING HIGH SPEED/HIGH STRESS OPERATION)

I've always assumed the Wankers that operate BMW automobiles have NO
IDEA/THOUGHT about Tire Safety and Avoid them on the Roadways Like the
Plague.[Flying Doctor Syndrome/A.K.A. American M.D. with a Pilot's License]

Now I have to start worrying about Mercedes owners !

Hey now, them's fightin' words! :D

Thanks Compress Ignite. That was very helpful and I am saving in My Favorites. I had my tires rotated and balanced today. It was 10,800 miles ago when I had them done at Firestone. They have 35K on them now (and I meant they were new, and now have 40K on them but could see how that read differently...my apologies) and Firestone said they looked like they only had about 15K on them and are in great shape. They had also inflated them to 36 psi and I had them put back down to 27 psi. I asked why they did this and said that is what they had in their system for my car...is that possible? My tires are rated at max 45psi (not low profile but standard). I will definately pay close attention to this area from now on and always check my tires correctly! Anyway, thanks to all for the helpful info.

Many,Many Moons Ago
 

I used to Inflate the First set of Michelin Xs I Owned to the Max PSI figure
ON THE TIRE SIDEWALL. 35 PSI
Foolishly, believing I'd get the best Fuel Mileage And Most Longevity of Tread.
Well,I did.
That SD regularly enjoyed 27MPG in mixed driving,with not a few JackRabbit starts.
The Michelin Xs (80,000 mile treadwear warranty from Michelin) still had usable
tread at 120,000 miles.

BUT,If I'd gotten "In a Tight Place" in an emergency the Tires might have shown
all that High Pressure Running to me in a way I'd have regretted.

Firestone (Goodyear? Bridgestone?)
 

Are in the Business of SELLING tires.
[AND relieving your Pocketbook/Wallet of the burden of excess cash.]

They are NOT in the business of inflating your Mercedes tires to the Proper PSI.

(Can you buy Michelins at Firestone?)

Please note My Caveat about Tires:

Michelin makes ROUND tires.
A bunch of other people Manufacture TugBoat Gunwale Protection Devices.
That I WILL NOT BE CAUGHT DEAD ROLLING AROUND ON.

I'll look into those Michelins next time! I have some Dunlops right now but would never expect 80-100k in any tires I have ever bought. Wow!

Agreed on inflation. When I have my oil changed (only when I don't have time) I often have to argue with them about tire inflation, they will check the pressures and tell me that they need more air per the sidewall. They don't understand that the sidewall pressure is the maximum for carrying the maximum rated load at the maximum rated speed, ...

I have found that 36PSI is the magical number for tire pressure on my TE. It minimizes tire roll under cornering, but is not super stiff under normal driving.... Also makes turn in a bit more crisp. :D

I ran mine to work today after deflating tires down to 27psi and getting rotation and balance done. The ride was Super Smooth and comfortable but I did notice it didn't handle as well at the front end but had less road noise and was much quieter which was very nice! Didn't seem to struggle any more on acceleration either than with heavier psi...:cool: