W123 Flaring 2-3
 

I just took my 83 300d for its first short drive and everytime it would flare (in between shifts the motor seems to free rev for a second or two, until I let off the accelerator and it goes into third) horribly into third. I've been reading this isn't all to uncommon for 123s, but it sure doesn't make me feel very comfortable. I tried adjusting the bowden and it only made my 1-2 noticeable and quicker/harder going into D. Maybe I should try getting a new modulator? It has brand new Castrol Dextron/Mercron III fluid (old fluid was pretty clean) with a new Febi filter in it. Any advice on how to best adjust this out or even knowing someone else's does this too would be great peace of mind, and very appreciated.

Thanks,
Jeff M.

For the last couple hours I've been piddling with the 83 and managed to get the flaring down to only like 500rpms which I can live with, for now. Before it sounded like I was going to hit redline before it'd shift. I found I have a minute vacuum leak on the line going to the modulator, it takes about thirty seconds for it to go from 14" to about 1" of vacuum. I noticed many of the rubber fittings on the end of the lines are getting all checked so I'm going to replace this anyway, but will this minute of a leak really affect my flaring problem anyway?

I also found this while looking around:
So it just has a cover which I pop off and give it a turn?

~jm

There should be a little rubber dust cap. It has been some time since I have done this, but if I recall correctly, you take it off and inside is a T shaped handle that you pull out and twist clockwise to increase pressure.

I would try to avoid any flaring if at all possible. It is my understanding that when the trans flares it rapidly wears your "clutches".

Someone very recently had posted how they changed the rubber connector between the plastic vacuum tube from the engine area going to the vacuum modulator valve. They said it didn't look cracked but was hard. They replaced it anyway and the results were "very impressive". There are MANY threads on this topic ... here is one:

Adjusting the trans mod valve

Haasman

Here is a side view of a trans which might help:

Thanks a lot haasman. Both my 300s really could use some tweaking in the shifting, this flare has to be horrible on the tranny. Picture really helped too, now I know where to look. :)

Jeff M.

Hi,

I have a 90 300CE, the trasnission was rebuilt about a year ago. The transmission started flaring about a month ago on shifts from 3-4, but only when the car is warmed up.

Seemed like most of the people said theres did it when it was cold. Do you think the spring kit will fix my problem as well, or could it be something else? Do you think this kit is a DIY job or should I have it done by a tech?

Thanks for your input, greatly appreciated.

Dean:
The kit that I posted the part number on specifically addresses the slipping or flaring on 2-3 upshift at partial load. I would hate to tell you to try the kit and screw something up. I'm not mechanic, but a flare at 3-4 might be low pressure at the vacuum modulator or a small leak.

I am sorry to post this again,but does anyone have any info on installing this kit? Any help is greatly appreciated for this DIYer.
I got K2 accumulator spring kit.

Thanks
95e320

Did you look at the previous pages to this thread? Does this help?

95e320: I do have an install diagram, but the spring kit that I had put in was the K1, not the K2. The K2 position is on the opposite side of the valve body.

My old 1977 280E, which my brother now drives, has a flaring shift from 2-3. Everything else is normal. It was doing this when I first bought the car about 100,000 KM ago. I was worried about it then and had it looked at several times by several techs, got it tweaked, etc. Nothing helped. So I just changed the fluid every 40,000 KM and she's still purring along, albeit the flaring shift from 2-3. The car's total mileage is around 300,000 KM, original transmission.

A tech once tweaked it so that the 2-3 shift was more smooth, but then the other gear shifts were not. I chose to live with the rougher 2-3. It really drops into 3rd with a solid clunk, but it has never worsened. It seems the rough 2-3 shift is not uncommon.

ESM6869,

Do you think this may be just a simple adjustment, or a vacuum leak? Any chance its a DIY thing? Should I start a seperate post?

This is my second transmission, since I ve had the car and Im verry easy on it. Kills me to think it may be going again.

Any input you have is greatly appreciated. Thanks in advance!

Sorry it was K1 not K2

Does that K1 spring apply to the 1992 300D 2.5 Turbo? I have increasingly worse 2-3 flare as the car warms up. No flare (or much reduced) when flooring it. I really want to get something like this installed before toasting my tranny!

Thanks much for additional info! This sounds like a life saving upgrade!!!!!!

-m

Mercedes300E:
Sorry I haven't responded...been out of town. When I was having trouble with 2-3 flaring and 3-4 flaring, the 3-4 flare went away when I had the vacuum modulator replaced due to a small tear in the bladder. I think proper adjustment and checking for a vacuum leak may help you. If you really want to get good information on your situation, private message "Joe P" at behind the Star in North Carolina or I think Gilly's screen name is "Gillybenztech" at Zimbrick European of Madison, WI. They were very helpful and offered great information to help me.