Brian Felts

Hey I am working on a buddy's E 300d when he shifts from park to reverse it goes clunk, and does the same from reverse to drive. This is the only time it does it. Any Ideas where I can start looking?

Brian

shadowgriffen

Flex disk.

Brian Felts

cool thanks......


Brian

mgw_300e

have you tried the basics, like checking the ATF level or changing the ATF and filter if needed?

How long has it been doing this? Is there a lag in the shift followed by a clunk, or is it shifting normally, but going "clunk" while it does it?

How are the transmission and engine mounts?

shadowgriffen

good point, although I tried that and it didn't work.

mgw_300e

yeah, i forgot about the flex discs

shadowgriffen

You may want to be careful filling your trans with fluid as well.

If you are going to top-off your trans make sure that you use a micro mesh filter. Any sort of debree that can enter your trans fluid reservoir can and will have an effect on your trans. Make sure that you dont overflow with oil or may very well end up in a smokey situation.

mgw_300e

Here's another tidbit of trans info:

If you are tempted, as I was, to put synthetic ATF in your trans - don't do it!

An MB mechanic once told me that synthetic ATF doesn't provide enough friction to allow the clutches to grab sufficiently. And this was a guy who could have made more money by letting me use synthetic!

shadowgriffen

I would be scared ****less just to think of how much oil would seep out through the seals, nevermind friction!

jeffreyli86

MGW,
I think my car once "shifted normally but clunked".. What's the cause of this?

Also, regarding the ATF, I didn't use MB stuff but it was to the MB standard. Should I flush it and change it back to MB?

Cheers

AMGDave

Lots of people are using Mobil-1 synthetic ATF in their 722.3 / 722.4 trannies. I use it in all my cars. No problems, works great. In many cases it improves cold shifting (less harsh). I've not heard of any problems related to synthetic ATF. If it causes any seals to leak, well, that's not the ATF's fault... it's a bad seal, lol. I had to replace the dipstick O-ring on one car but that's about it. If you stick with plain old Dexron III, make sure you replace the fluid & filter at least every 30kmi, if not sooner. Don't forget to drain the converter too (many people don't do this.) And as mentioned above, DO NOT overfill. It's better to be a little low on fluid than a little high!

Anyway, the clunk described in the original post is pretty likely to be one of the flex discs. If they're bad, it's very obvious once you go under the car and look at them. There should be zero free play between the yokes on either side.

mgw_300e

do you mean it used to go clunk and now it doesn't?

as far as atf goes, if it meets mb standards, then it sounds ok to me.

AMGDave

You are 100% correct... using standard fluid is fine. Just make sure you change it every 30k for normal service, or 15k for "severe service", per MB recommendations.



For the record, the main advantages to synthetic ATF are, IMO:

1) Shifts tend to be more consistent, regardless of temperature... some cars shift pretty hard in sub-freezing temps, synthetic helps with this. Not a big deal if you live in a warm climate.
2) The tranny runs cooler with synthetic, extending tranny life, and also reduces the cooling load on the engine as well (the ATF cooler is inside the radiator.) This is more important in summer, especially in warm climates
3) In my cars, with standard fluid, the tranny would start shifting harder around 20-25k. When the fluid was changed at 30k, shifting went back to normal. With synthetic, it has been fine through 30k.
4) There's a slight increase in fuel economy too.

Sorry for the thread hijack, I'm just a big fan of synthetics, lol. At least in the engine and tranny. I've haven't had the same luck with differentials, though. I won't switch any more high-mile diffs to syn. Twice now after 20-50kmi they started to get a slight whine. D'oh. May not be related to the lube, but there's no way to tell for sure!

CharlestonN

My tran recently started clunking when shifting from P to R then from R to D but only in the morning after i first start the car but all day after that it shifts smoothly and runs great, i just had my flex disk replaced as well

AMGDave

That's a different issue. It's officialy called a transmission "double engagement jerk". The fix is to tear apart the tranny and replace the B2 band. Here's the official Mercedes service bulletin:

http://www.w124performance.com/docs/...dbl_engage.pdf

I tried the (very expensive) special fluid - it didn't work. I have this problem in both of my 300D's. I just make sure I don't stop on the pedal when I first put the car in "D" in the morning. After that, it's fine.


Here's links to photos of the 5 liter jug:

http://www.w124performance.com/image...d_special1.jpg
http://www.w124performance.com/image...d_special2.jpg