1982 240d highway screaming.....
 

WOW! At highway speed 70mph+ the 240d 4-speed seems like it's gonna pop the motor through the hood!! :eek:

Drove to Lakeland for the Lake Mirror Classic Road Rally yesterday and had a blast!! But have to tell you that the RPM's that this 240d spins at highway speeds makes me uncomfortable(I would expect the speedo to be 100+ mph in any other car!!!). Honestly there is only like 1/2", if that, till it's floored!

Can you tell me what kind of drop in RPM's will I experiance if i go from the 185-70R-14 up to 205-70r-14 ?

Or should i not waste my time with that and swap rear end gears?

Love this car!! :)

It's a 240D. It's not a speedster. Mine does the same thing on the interstate if I go that fast. Usually I keep it around 65 and I have 195/70/14 tires.

The only really sensible change is to locate a five speed transmission and get it installed. They are scarce but still out there.

The only rear end ratio change I would otherwise consider is the 3.47 from any non turbo five speed 123. Your present ratio is 3.69 so the improvement is only 7 percent if I remember. Yet seven percent is still a step in the right direction.

You in my opinion do not have enough power to go to a much lower ratio rear end in my opinion. I have two 240ds by the way. Also you will need the speedometer head from the donar car.

I personally believe that a five speed with a 3.47 rear end would be the best possible combination for a 240d. The slight background noise at 70 that takes a good sterio to overcome varies from car to car. For example one of mine is really noisy at 70 in comparison to the other.

If you like the car basically take the time and effort to get the fuel pressure right in the base of the injection pump. Yours may or may not be where it should be.. Find out. It makes a difference in many ways.

Gator, LOL yea it's not very speedy! just trying to make it a little better on the highway.

Berry, I'm still catching myself wanting to reach for the non-existant 5th gear. Yes 7% is a step in the right direction. you are the 2nd person who has mentioned the fuel pressure/injection pump settings, I will look into that. Thank you!
I'm ok in my local commute to work cause i can travel the highways. It's when i wanna run up the interstate that's uncomfortable. If my calculations are right (adding 7% to my comfortable rpm/speed of 65mph) 7% gets me 69.55mph at the same rpm.
If this darn car was not so nice I'd sell it for something more interstate friendly.

Finding the elusive five speed transmission in your local with a little due dilligence. Just has to be far easier than in mine. In my opinion it also adds to the value of the car when you eventually sell it.

The general serviceability improvement has got to be worth the effort alone. Try to get the driveshaft as well if you do locate one as the length is different. The shifter and linkages must also be with it as they are as rare as well.

If you accedentally stumble on one you do not use drop me a line. Two have slipped by my fingers so far. I do not want the third one to get away.

contact funola about the fuel pressure testing. he has a cool little kit to measure the pressures.
it should be little difficulty to find a 300D from 77-81 to pull a speedo and diff from (pull the axles too, if the boots aren't torn!)

Take it up to 74mph and it will quiet right down. Seriously, you are not going to blow this thing. I can cruise 70-75 all day long. Granted it is not the quietest car made, but I have been in worst. Just drive it. Make sure all the holes and gaps in the firewall to the cabin are sealed for noise factor. Hood pad helps too if you don't have one.

Get a 83 rearend assy with 3.07.gear stamped on the lower left bottom part of the.cover. And also get the speedo head.from that same.parts.car.to make.speedo.and odo correct take.off power will.suffer.some.but hiways.rpms.will be way down

you got.3.69.gears now

My 240D was a completely stock '77 four speed. I used to do like Jerry Reed said, "Put that hammer down and give it hell". There were occasions when I kept it floored for an hour or more at a time. The limiting factor wasn't the car, it was my right leg. The car handled it just fine. Fuel economy did suffer a bit when I drove like that.

Whats your.all highway.mpg like.trying.to get the.most.you.can ?

Something doesn't sound right. I realize that "loudness" and "about to blow" is subjective, but from my experience it's not that loud or bad sounding. The car should be a fairly comfortable (again, subjective) at 70-75 mph.

Is maintenance current? Also, you mentioned something about 1/2" and floored...accellerator linkage adjusments and shift bushings (if applicable) may need some attention.

I drive 100 miles at 70MPH three times/week. I do occasionally get up there and reach for the invisible 5th gear, but most of the time I don't even think about it. The engine is running fast at that speed, but it doesn't seem that loud to me.

Sounds like squashed motor mounts, possibly.

A five speed would be the ultimate as Barry says. I agree with him too that you dont want to go taller than the 347 gears in a 240d.

Back when a 240 was my primary car I tended to keep it at no higher than 72 mph on the highway. Faster just seemed too frantic.

You'll get used to it. I drove my 240D manual transmission cars 80 MPH for a combined almost 800,000 miles. Maybe you can consider a noise cancelling headset. The revs won't hurt anything as long as it's full of oil.