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-   -   722.120 3-4 Shift Anomoly (http://www.peachparts.com/shopforum/diesel-discussion/338741-722-120-3-4-shift-anomoly.html)

Doktor Bert 05-12-2013 12:27 AM

722.120 3-4 Shift Anomoly
 
Hey, Gents....

96,000 miles now on my 617.950/722.120 rebuild and today I experienced a strange thing.

All shifts on my 722.120 are solid, with the 3-4 having always been the softest shift, but never any hint of slippage, just not as solid or 'firm' as all the others.

Today, under moderate throttle, I experienced what felt like a "up-down-up" shift. No slippage or engine RPM increase, just like a "shudder" but (3) very distinct shift events all at once.

Under light throttle, it shifts normally and as a precaution, I really babied it home today as I was over 100 miles from home when it started, so I could really use some answers.

Fluid and filter were changed about 30-40,000 miles ago and it was clean when changed. No metal or anything in the pan. The fluid is red and smells clean and fluid is full.

Bands....I must admit that I haven't adjusted them in many years, IF ever since the 2005 rebuild almost 100,000 miles ago, but I don't think the bands have any influence on the 3-4 shift, IIRC.

Thoughts?

Now I did read once where a forum member said he experienced this whenever he ran over 20,000 miles on his trans fluid and when he changed fluid and filter, the 3-4-3 went away.

I will admit that doesn't sound right to me, but one should always keep an open mind.

Thanks for sharing your experiences!!!!!

Doktor Bert 05-12-2013 12:45 AM

P.S. My trans is 100% stock. However, all my other shifts are so solid that I don't know if you would want to increase line pressure, as it would affect all the shift points.

IIRC, the 722.120 only has a reverse band adjustment, so no advantage to doing that.

All the shift kits I found only go back to 7.22.3XX

Hmmmmmm.....

Doktor Bert 05-12-2013 12:46 AM

1,333,000 as of May 11, 2013 - 96,000 on engine/transmission since the 2005 overhaul.

Stretch 05-12-2013 02:43 AM

Going from 3rd to 4th the B2 is released and the K2 is applied (K1 should stay put!)

http://www.peachparts.com/shopforum/...ents-gears.png

http://www.peachparts.com/shopforum/diesel-discussion/304903-722-118-automatic-transmission-rebuild-monster-diy.html

If I were you I'd measure the pressures (hydraulic and vacuum) and check the linkages first (I guess you have the data - but if you need it I can help)

Doktor Bert 05-12-2013 11:32 AM

K2 spring is in the valve body, IIRC? I have seen this spring changed in the 722.3xx uints, but they won't fit the early ones.

I'm at a complete loss for tools where I am now, except some very basic things...

Doktor Bert 05-12-2013 11:42 AM

Ok,

Based on the shift point chart, on a 116.120, the 1-2 should take place at 12kmh, the 2-3 at 33kmh and 3-4 shift @ 45kmh.

My 3-4 light-throttle shift has always taken place at 30 mph, so I am even a little higher than specification.

Doktor Bert 05-12-2013 12:27 PM

Luckily, I had my vacuum pump in the trunk. The modulator held vacuum, so I turned the T bar in from 3 O'clock to 6 O'clock, roughly 2 notches. I guess we will see...

Doktor Bert 05-12-2013 01:09 PM

The short rubber hose between the nylon tube and the modulator was a bit loose feeling, so I changed it to a section of silicon hose.

For many years I have always used a 3 foot long coil of silicon hose between the vacuum pump and the gray line going into the car.

This allows me to always have spare rubber/silicon tubing on hand on the roadside...

Stretch 05-12-2013 01:49 PM

Good luck with the adjustments I hope that they work out - it sounds promising.

Please note - it could be K2 - but it might also be the dreaded B2 not letting go.

If you need a map of the valve body I have some pictures in that thread that should put you in the right direction (please note my 722.118 valve body is the vacuum only variant so it doesn't have the modulator connection to the throttle linkage you've got)

http://www.peachparts.com/shopforum/...r-springs2.jpg

http://www.peachparts.com/shopforum/...om-springs.jpg

Alastair 05-13-2013 07:59 AM

Maybe its as simple as needing its fluid and filter changing....

I think that is what I would try first.

After that, vacuum system and line-pressure checks etc...

Stretch 05-13-2013 12:15 PM

Quote:

Originally Posted by Alastair (Post 3145375)
Maybe its as simple as needing its fluid and filter changing....

I think that is what I would try first.

After that, vacuum system and line-pressure checks etc...

Good point - I sometimes forget that other people can read these threads too! I was sure that Doktor Bert already knew that so I skipped the basics.

shadetree77 05-13-2013 09:51 PM

check that bushing on the "bowden rod" that connects on the transmission end, mine was gone and resulted in some funky shifting like you described. all's well after replacing that bushing

Doktor Bert 05-14-2013 05:14 PM

Fluid was changed in 2011, but its certainly time for it again no doubt.

Turned the modulator on the roadside from 3 to 6pm and shifts are back to normal.

Will check pressures/vacuum when I have the car back near civilization...

Doktor Bert 05-15-2013 06:04 PM

Hey, thank you Stretch....

Thus far shifting great and still on the road!

Stretch 05-16-2013 01:16 AM

Great stuff!


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