How much flairing is normal between 3-4th in a '82 300sd? Mine seems to flair what seems like alot (1-200rpm) under light to moderate acceleration, but very little when floored. Is this normal, if not what can be done?

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82 300SD 100K
91 Caprice SS
92 Jetta TD

It may be normal put it ain't proper. No amount of flair is proper. If you have a virgin 82 tranny then there are a number of reasons for it flairing. The band for second gear had its friction coefficient lowered so that the modulator/shift pressure could be raised without the harsh 1-2 shift. The valve body was extensively modified with a different intermediate plate with different sized holes to improve flow to fourth gear clutch pack. The free play on both clutch packs were reduced to allow quicker fill times.

If the tranny is over 150k miles old it should be resealed .... or lived with till the next failure.

BTW the control mechanisms are just under infinitely adjustable. Which do you hate more; harsh 1-2 or 3-4 flair. As a quick improvement I would tighten the modulator one turn and make the car shift earlier by a turn and a half on the control pressure cable. If I was doing it I would also shorten the vacuum span and modify its relation to the throttle. But just do those two reversable adjustments and tell me what happens.

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Steve Brotherton
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician

Steve:
I don't mind a harsh shift near as much as I hate the flair. Can you please give me directions to the modulator and what exactly do I turn?
The tranny has just over 100k.

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82 300SD 100K
91 Caprice SS
92 Jetta TD

The modulator is on the drivers side front of the trans. It is plastic and will probably be green in color.

In the center is a black rubber cap the diameter of a nickel about a quarter inch tall. The cap easily pops off, under it is a castelated circle. There is a steel tee handle locked into two of the castelations. The tee handle easily is removed to the point the castellations no longer keep it from turning. Once in this position screw the key one full turn (maybe more) clockwise and push back into the castellated locks. Replace the rubber cap and try it out.

The adjustment is reversable as long as you keep count. You probably can't hurt anything no matter how tight you get it. I have seen the result of over pressure: it brakes the second gear band servo piston which is one of the modifications done on a proper rebuild anyway.

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Steve Brotherton
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician

[This message has been edited by stevebfl (edited 05-12-2000).]

Steve;
I made the adjustment today, I turned it in 1.5 turns. Great improvement but still a little flaring. Is it possible to get rid of all the flaring or is it a sign of a failure to come? Can I turn it in more or is there a danger of causing damage?

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82 300SD 100K
91 Caprice SS
92 Jetta TD

Could someone please explain what flairing means?

As I understand it, is an increase in rpm as the tranny shifts to the next higher gear. Normally there should be no increase in revs.
If I am wrong someone please correct me.

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82 300SD 100K
91 Caprice SS
92 Jetta TD

PT,

"Flairing" is a form of "slipping",but totally different. During "Slipping" the drive member is rotating with respect to driven member. This occurs because the pressure pressing them together isn't holding either due to a lack of pressure (usually seal related) or lack of friction material (clutches/band wore out).

During "flairing" the transmission is actually in neatral for the briefest of moments and engages thoroughly once the event is over.

In the case above the second gear band is being released and the fourth gear clutch is engaged. During the event pressure builds against the 3-4 command valve and fills the chamber behind the 4th gear clutch pressure plate. As the fluid builds pressure the drum (pressure plate) starts applying and the piston starts moving. At a point just before clutch lock-up the piston moves against its spring and the pressure to the second gear band servo is dumped. At this moment the car is in neutral (no members engaged). Almost instanly the clutch engages and the event is over.

During normal activity there is overlap during this shift change. What has happened here is that there is no longer overlap actually a gap. This is called shift timing and is built into the hydraulic control system (valve body). The case mentioned above is special because the first models 722.3 transmission had built in deffects to this timing issue (read my first post above).

This condition is usually a precurser to slipping due to wear or lack of sealing of the clutch drum. What you have to remember is that fluid flow unlike electrical flow takes real time (electrical times aren't real {bg}). As the clutch seal wears more fluid pressure is necessary before the drum moves; thus the command valve moves earlier compared to the movement of the drum, the same occur if the clutches are set up too loose(one of this trannies original defects)or worn considerably. In these cases the drum has further to move to take up the play and delays that portion of the shift.

In reguard to M's car, unfortunately the proper next adjustments get complicated and are something akin to "playing music by ear" and I can't hear the tune from this distance. The next move is to get your shifts at a more significant throttle position (or have the vacuum system represent this). This requires making the tranny shift earlier - did you make the control pressure adjustment I talked about above - its just as important as the modulator.

The modulator and control pressure cable adjustments are reversable because the adjustments are quantified. The adjustments of and to the proportioning valve aren't so. I wouldn't try to advise on them without some vacuum values.

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Steve Brotherton
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician

Mreid,

I had the same problem in my 84 300SD (117k miles) that I just bought. Flaring between 3rd and 4th gear. It also had the rough shift between 1st and 2nd (which the used car dealer told me was normal). There were bubbles in the fluid when it was warm too. The flaring didn't start until about 200 miles after I bought it. But everything worked fine under hard acceleration, and when it was cold.

I took it down to the dealer to get the transmission inspected, and they found a bunch of metal in the fluid and said that means it needs rebuilding. So I drove it down to the shop affiliated with the used car dealer where I bought it (had more tranny problems on the way: couldn't get into 4th gear at all, then it came out of 3rd and I just had neutral).

So the transmission mechanic test drives it and says the clutch is bad and he's going to rebuild it. He actually got it to go into 4th gear when he drove it, but not until it got to like 5000 rpm in 3rd.

I hope your problem isn't as bad as mine was. Good luck!

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Dean
Santa Barbara, CA
1974 280C
1984 300SD

Steve

All I have done so far is the modulator adjustment. I need a little more tech help on the control pressure adjustment. Could you please guide me through this one. Exactly which cable or rod are we talking about? Where is it located? etc. etc.

Thanks

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82 300SD 100K
91 Caprice SS
92 Jetta TD

The control prssure cable adjustment is in the linkages on top of the valve cover. It is even easier than the modulator.

There is only one cable so finding it is no problem. The cable has a ball socket on its end and is attached to its own activation lever. The adjustment is where the cable housing end is mounted. It is a 14mm wrench size white plastic nut. Turn the adjustment 9 flats (1.5 revolutions) in (clockwise). This will shorten the cable and make the trans shift earlier.

The point of this is to get your part throttle shifts at a greater throttle. In other words you will not be lifting your foot as much to get the shift; you will have to keep your foot in it to get later shifts.

The only reason this works is that it affects 3-4 more than 1-2. You are trying to get a stronger 3-4 shift without affecting 1-2.

You can keep adjusting modulator pressure but I can't tell how hard your other shifts have become.

BTW as I have said before on a late 83 and newer the chances are you have clutch problems with these symtoms. If you have metal in the pan on servicing all these adjustments are temporary as everything changes quickly in the end.

Also you are likely to blow the second gear band servo piston after a while at very high pressures. If your problem isn't filling the pan with metal I would think that shift technique could make this thing last indefinitely. You could hasten a repair by taking the pressure too high.

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Steve Brotherton
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician

steve

I found the cable, I guess that is what they call the bowden cable. By turning that in it makes slack at the stop, is that ok? You also mention bringing pressures up to high. Is that done by the cable adjustment or the modulator adjustment. I have not taken the pan off but the oil is as clean as new so I am assuming that I don,t have metal in the oil.
You help on this great appreciated. Thanks

Mark

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82 300SD 100K
91 Caprice SS
92 Jetta TD

Pressure is adjusted with the modulator.

Having slack isn't the way it is supposed to be but we are trying to outsmart the beast. I would prefer to have you adjust the prroportioning valve range but that isn't easily reversable and I really would need some vacuum readings to keep you from getting all screwed up.

Steve

The adjustments I have made with your guidance has greatly improved the shifting. 1-2,2-3 are noticably harsher but not bad in my opinion. There is still some flaring from 3-4 but a lot less and not every time. One further question. Is the flaring harmful to the tranny or is it more an annoyance? :)

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82 300SD 100K
91 Caprice SS
92 Jetta TD

Steve, thanks for the info re flairing.

My car is a Euro '87 300D 4matic which shifts fine on all gears. I've noticed though that when I floor the acc pedal to activate kickdown switch, the engine RPM goes excessively high for approximately two seconds before lower gear shift is fully engaged. At this point, RPM drops to normal.

Tranny seems to be slipping for a short duration.

Is this normal? If not, how can I improve it?

Thank you for your posts. I've learned a lot from them.

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Jake