'67 250S top speed? - PeachParts Mercedes-Benz Forum

dmtinker · #1 10-19-2007, 07:22 PM

What would be the top comfortable speed of this car? Do you think it will do 75mph without straining it?

todds · #2 10-19-2007, 07:35 PM

It certainly won't strain the car to do 75mph. On the other hand, the axle ratios are pretty high and it will sure be revving at that speed! My car (w111) would be spinning close to 4000rpms, not sure about the w108's...

If you're comparing to most cars it'll seem like it's revving too high. The difference is that it can do this all day long and be perfectly happy.

Mike D · #3 10-20-2007, 08:19 AM

Due to wind resistance, 176.5 FPS in freefall.

The W123 can acheive a greater speed by virtue of the changes in aerodynamic styling.

t walgamuth · #4 10-20-2007, 08:39 AM

my 190c would do 90.

I imagine a good running 250 should about touch a ton.

Tom W

hjrios · #5 10-20-2007, 09:09 AM

my 67 250s has done 95mph on Sunrise Hwy on the way to the Hamptons

screaming like a banshee but riding smooth as silk

dmtinker · #6 10-20-2007, 09:40 AM

I'm just looking for a good top end cruising speed where you have a little left and are not killing the gear box.

t walgamuth · #7 10-20-2007, 11:03 AM

It won't hurt the gearbox.

Probably up to 70 no problem.

Tom W

Chas H · #8 10-20-2007, 11:13 AM

I can't see any reason why the gearbox wouldn't be able to run flatout, or the engine for that matter. When these cars were new there was no speed limit on the Autobahn.

300SDog · #9 10-20-2007, 03:17 PM

From experience, drove 220Sb cross country New York to Colorado at speeds upward around 90-95mph. I think if you ever hooked up tachometer you'd be amazed how M180 engine growls nowhere near its redline. I'll betcha 65mph is actually lugging the engine.

Todd Miller · #10 10-21-2007, 12:50 AM

If it doesn't already have 14's, that would be the cheap way to make it a nice freeway cruiser. Those and a big tall set of 14's are a nice upgrade and you can keep the stock look of your hubcaps and (buy a set of 14's) beauty rings.

If you want a step up from that, install the complete rearend assembly from a 4.5 V-8 w108. It's bolt in, plug-n-play.

My coupe came with 14's and was still just screaming on the highway. I opted for the 4.5 rearend within a few months of buying it. What a nice change.

Q45Denver · #11 10-23-2007, 01:58 AM

Quote:

Originally Posted by Todd Miller

If it doesn't already have 14's, that would be the cheap way to make it a nice freeway cruiser. Those and a big tall set of 14's are a nice upgrade and you can keep the stock look of your hubcaps and (buy a set of 14's) beauty rings.

If you want a step up from that, install the complete rearend assembly from a 4.5 V-8 w108. It's bolt in, plug-n-play.

My coupe came with 14's and was still just screaming on the highway. I opted for the 4.5 rearend within a few months of buying it. What a nice change.

Is that the limited slip rear end. What specific changes did you notice?

Todd Miller · #12 10-23-2007, 10:52 AM

I don't believe it's limited slip, but I don't know.

The changes I noticed were that the engine is turning about 900rpms less at freeway speed. Still plenty of power around town and for hard acceleration like getting out on the freeway.

wbain5280 · #13 10-23-2007, 11:32 AM

All these cars are made to run flat out. Engine speed is not an issue, other than over revving usually past 6000 rpm. The speedo has marks on it for max speed in the lower gears. 4th is limited by aerodynamics, or lack or it in the W111/108 based cars.

Todd Miller · #14 10-23-2007, 01:11 PM

One thing we might be forgetting, is the gear ratio change that all these cars now suffer from since the big tall bias ply tires are no longer available....at least at a cost that's affordable to most, not to mention do you really want to drive on them.

That being said, yes, I know that the cars were high reving from the factory, especially compared to other stuff of the same time, and to todays cars. That doesn't mean they're enjoyable to drive at those high revs if you're out on the road for any duration. At least it isn't to me.

In my car's original configuration, both the tach and the speedo were straight up at freeway speed. That equates to about 3,800rpm at 68.75mph/110kph. Neat for around town, or a couple miles on the freeway, but when it's time to get out and go somewhere at a decent speed, and keep in the flow of traffic, 75 is a lot nicer. That would be about 4,100rpm in my car originally.

With the 4.5 rearend, 75mph is more like 3,200rpm. The car is much quieter inside, the engine isn't screaming along. Taking it on road trips is not a problem.

todds · #15 10-23-2007, 04:58 PM

Weren't the fintails some of the first cars to come with radials? I believe if you search for the ponton tire sizing guide that modern radials in 185/80/13 size are virtually identical to the 6.20-13 size originally spec'd. I don't think the revs at speed being experienced now are any different than they were in the 60's.

That said, I COMPLETELY agree about the benefits of a more relaxed ratio and believe the original ratios are overkill on these old Mercedes. Why should my gas 6-cylinder have the same ratio as a diesel 4-cyl with half the horsepower???

Conversely, I find myself driving my girlfriend's 2005 saab with an auto 5-spd in manual mode most of the time so I can hold 3rd or 4th and start out in 2nd. I think cars nowadays have gone too far the other direction for axle ratios. I understand it is for purposes of economy and the turbo in her car helps avoid upshifts sometimes. Regardless of that I find the super low ratio VERY annoying on the highway at regular Boston speeds while the constant shifting of the 5-spd at low speeds is equally annoying as well. I suppose automakers have no other choice in the neverending quest to bring 0-60 times down and economy up. Unfortunately this makes for very distracting day-to-day behavior.