240D Differential swap - Page 2 - PeachParts Mercedes-Benz Forum

mannys9130 · #1 12-02-2015, 07:27 PM

Quote:

Originally Posted by Grzpdlr

Way, way different from a 240D, 4sp

I'm aware. I've driven a 240D 4 speed and you are way too early. I gave my 190D 2.2 points as comparison. Similar hp/weight ratio, not exact.

These IDI engines are not like DI engines. They need to rev to make power. They redline at 5k, not 3k.

mannys9130 · #2 12-02-2015, 11:53 PM

The 240D 4 speed I drove was an 83 and I couldn't fathom putting a diff of anything lower in it. It was slow as it was, and you had to wind each gear out to its max if you wanted to merge safely. A 240D with a 2.88 would be undriveable IMO and Tucson is flat. That's taking the diff from a car with twice the horsepower!

charmalu · #3 12-03-2015, 01:15 AM

From a 3:69 to a 2:88 is lower numerically but actually gearing it higher.

Now if I started out at 3:69 then by the time I was in high gear at 2:88, that would be cool.
But probably need a 6 or 8 speed trans.

Charlie

Sent from my pos computer

rotorbudd · #4 12-03-2015, 03:14 PM

I've got a 83 240D that spends 75% of its time on the interstate. (back and forth to work every weekday)
I've got a 3.07 diff I'm thinking about dropping in, along with rebuilt driveshafts.
Around ATL if you can't do at least 75mph on the interstates you get eaten up by everybody including the big rigs.
Anybody think this wouldn't be a good mod, and if not, why not?

barry12345 · #5 12-03-2015, 05:29 PM

Quote:

Originally Posted by rotorbudd

I've got a 83 240D that spends 75% of its time on the interstate. (back and forth to work every weekday)
I've got a 3.07 diff I'm thinking about dropping in, along with rebuilt driveshafts.
Around ATL if you can't do at least 75mph on the interstates you get eaten up by everybody including the big rigs.
Anybody think this wouldn't be a good mod, and if not, why not?

Better still to locate a five speed transmission perhaps.

Grzpdlr · #6 12-06-2015, 02:37 PM

Quote:

Originally Posted by mannys9130

The 240D 4 speed I drove was an 83 and I couldn't fathom putting a diff of anything lower in it. It was slow as it was, and you had to wind each gear out to its max if you wanted to merge safely. A 240D with a 2.88 would be undriveable IMO and Tucson is flat. That's taking the diff from a car with twice the horsepower!

Had a chance to drive the car some this weekend and it's no problem starting on a very steep hill from a standing start, even with four adults in the car. On level ground it launches with no discernible difference from before the modification so it's doubtful significantly increased clutch ware will be a problem.
Also if you look at this:

190D 2.2 .................240D-2.88 Rear end
final gear ratio
1. 14.47
2. 8.07 ............................1. 11.232
3. 5.13 ............................2. 6.62
4. 3.42 ............................3. 4.06
5. 2.873 ..........................4. 2.88

The car now drives like it has the 5th gear is so badly needed. Now I can actually keep up with traffic on the freeway without feeling I'm harming the motor. The RPM's at 70 MPH has dropped from 3542 to 2762 (calculated) and, with the 3rd muffler I added, it's now possible to carry on a normal conversation at 70 MPH.
There have been a lot of negative comments on this, none by anyone that's actually tried it, but IMO, it's probably the best modification that can be done to improve drivability.

t walgamuth · #7 12-03-2015, 03:33 PM

I think with a 307 you might have trouble holding it steady at highway speeds without downshifting to fourth.....and forget taking off on a hill.

rotorbudd · #8 12-03-2015, 03:48 PM

Quote:

Originally Posted by t walgamuth

I think with a 307 you might have trouble holding it steady at highway speeds without downshifting to fourth.....and forget taking off on a hill.

Hell, if I had a 5th gear to downshift from I'd be in heaven!

t walgamuth · #9 12-03-2015, 07:31 PM

The hit man! Haven't seen you around here for a while!

Hit Man X · #10 12-03-2015, 08:05 PM

Quote:

Originally Posted by t walgamuth

The hit man! Haven't seen you around here for a while!

I lurk often, most of the W126s are still full steam ahead and recently added a W124. SDL is down for a top end, SD is just about to receive a new front end (that Klimakit Sanden swap is still best thing I have ever done to it). 300SEL is a dog but rolled 308k recently, 560 needs front springs.

Glad to see you are doing well!

t walgamuth · #11 12-03-2015, 10:54 PM

Your flock of benzos sounds very impressive! Clearly you are doing well.

swampmonkey · #12 12-04-2015, 06:20 AM

i have the same setup.. in w115 thou, both with the newer w123 240d engines.

car nr1.
a 240d 72hp with a 3.07 differential.
http://mbturbo.com/car/w115-om616-240d/

carnr2
a 240d 72hp with a 2.88 differential.

the 2.88 is much much faster, both engines are bad, much blowby, and overal nasty.
the 2.88 is healthier, and with a better tuned injectionpump. better timing, etc.
the 3.07 smokes nothing at al, so thinking about dialing it up a tad.

https://www.youtube.com/watch?v=ab27eba8TKY
thats the 3.07 equiped car.
do know that the speedometer is way of, at that moment shows about 10-15km/h to little vs real speed. and starting in a slight uphill.

ps sorry about the nasty upshift.

ontopic.
i would not say they are peppier than stock, but much less noise,
the differense probably feels larger than it is to, longer pulls on each gear, and the longer pulls makes it feel marginaly slower, but you also gain much more speed.

i run 195/65r15 on my cars.

i have no problem reaching 75mph, even with the torn engine.
and hills etc is somewhat easy.
below 45mph in fourth it will loose momentum at steep hills, but above 60mph, its almost "unstoppable" althou, it do loose some speed, but not much.

ps, i swap to fourth gear in about 40mph with the 3.07 in place, imo the gearing is way of stock. when joining a highway etc, i switch to fourth at about 50mph
with the stock 3.69 the first gear was more or less useless, and fourth came on from 25-30mph. (after i swapped to good enginemounts etc)

pj67coll · #13 12-04-2015, 08:25 AM

Quote:

i have no problem reaching 75mph, even with the torn engine.
and hills etc is somewhat easy.

That's an interesting video clip but the speedometer is in KPH not MPH.

- Peter.

swampmonkey · #14 12-05-2015, 08:39 AM

Quote:

Originally Posted by pj67coll

That's an interesting video clip but the speedometer is in KPH not MPH.

- Peter.

i know it is, but i recalculated it, i have no problem reaching 120km/h,
but since you guys mostly seem to be in the us, i thought it seemed more fit to write 75mph.

swampmonkey · #15 12-04-2015, 06:39 AM

on normal diesel ive done 38mpg, on the older "real" diesel 41mpg.
that is at about 60mph and long drives.

mixed aggresive driving they do about 33mpg

yes, al om617a (turbo) from 1985 had the 2.88 (in US), not in sweden thou/europe, so information might differ depending on what website you visit.
we never had the turbo in the coupe nor sedan w123 either, nor the w116 or w126 with dieselturbo

ps. Sweden diesel. might have more energy than the US, and the old "real diesel" is better than the one bought at pumps.