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  #16  
Old 05-10-2001, 05:31 PM
jrd jrd is offline
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Join Date: Jan 2000
Location: Oakland, CA
Posts: 52
I ordered a new modulator valve and thought I would get around to installing it. It went out around Christmas and by end of April I still hadn't installed it. The transmission was shifting so hard that the shifter would move from D to 3 and I could feel the transmission oscillating on the mounts.

I decided that letting this wait any longer would be a poor idea. I went to a reputable shop in Oakland and they had no problem installing my modulator. They did write "Install customer-supplied modulator" on the work order; it was understood that they could not provide a warranty with someone else's part.

They also replaced the modulator piston with their part and were happy to take my $185. I got good (if a little firm at times) shifting and a new modulator that will surely last another 200,000 miles. I had already purchased the modulator and it would have been silly to insist on using their own modulator when they're the same simple, inexpensive rubber part.

I could see how you would want to avoid a customer-supplied engine or transmission. But worrying about who supplied the modulator seems a little excessive.

Respectfully,
Justin
Oakland, CA
1987 300D Turbo 201k

[Edited by jrd on 05-10-2001 at 07:57 PM]
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  #17  
Old 05-10-2001, 07:06 PM
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Join Date: Feb 2001
Location: Brandon, MS
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AV,

Were you able to locate the Job# on the CD manual for changing out the vacuum modulator?
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  #18  
Old 05-10-2001, 07:48 PM
mutigerfan
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Me too?

I have an '83 300d with the same problems jrd describes, but not as severe (It revs as it tries for 2nd and 3rd while accelerating. Then it clunks when I slow down, nearly to a stop).
Does this same modulator valve solution apply to me?

[Edited by mutigerfan on 05-10-2001 at 07:04 PM]
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  #19  
Old 05-10-2001, 08:47 PM
AV AV is offline
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Location: Toronto,Ontario
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Flaring

Marks88,

Thats exactly my situation too.However mine exibits this problem only occassionally and does only once in a day and thats it.Will never repaet again the same day.
I hope this helps.
AV
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  #20  
Old 05-10-2001, 09:01 PM
jrd jrd is offline
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Is the fluid reasonably fresh, i.e. changed some time within the last 20,000 miles? Did you check the level after a 10+ mile drive with the engine running?

Intermittent flaring can be caused by dirty fluid. (I had intermittent flaring in the 2->3 shift but the other shifts were fine. New fluid fixed the problem for me and the shifting has been fine for the last 20,000 miles, save for when the vac modulator died. (A failed diaphragm in the modulator will make the shifting very firm.)

Justin Dobbs
Oakland, CA
1987 300D 201k
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  #21  
Old 05-10-2001, 11:56 PM
mutigerfan
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:)

Okay. I will look into the fluid thing. I was really wondering whether or not I may need a new transmission and what to expect-ask for (diagnostic wise) when I took her to the shop next time...
Thanks for the suggestion.
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  #22  
Old 05-14-2001, 12:07 PM
Primo
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I just had the Transmission Modulator Valve replaced on my 1987 300E. Symptoms were rough and jerky shifting. The valve also exhibited a leak as there was ATF underneath the rubber cap which conceals the adjustment tee. This usually indicates that the diaphragm inside the valve is bad. Replacement of the valve is the only option at this point. I do notice a huge improvement in the quality of the shift. I may want to tweek the adjustment a bit, but it shifts much better now!
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  #23  
Old 05-14-2001, 02:29 PM
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Location: Brandon, MS
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Primo,

What was the cost of the replacement of the modulator? How many miles are on your vehicle?
I have been having trouble with a 2-3 shift flaring. I'm trying to determine if it is a bad modulator. Tks...

Marks88
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  #24  
Old 05-14-2001, 04:15 PM
Primo
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Marks88,

The part is around $30 and it took my mechanic a 1/2 hour to install the modulator and test drive the car. Not a big expense IMHO. FYI: My car, a 1987 300E, has 113,000 miles on it. Though I didn't do the repair myself, it seems like a fairly easy fix. The valve's location is very accessible if you put the car on ramps. It's on the tranny housing on the driver's side.......there's a vacuum hose attached to it. I'm not exactly sure though how the valve attaches to the tranny, maybe it's a non-threaded, twisting type mechanism. You may want to ask one of the many very informed people who frequent this site.

Good luck!

Primo
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  #25  
Old 08-13-2001, 05:31 PM
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Location: Canada
Posts: 127
Update on trans flaring...could it be the Lubegard?

More than 3 months ago, on the suggestion of Steve Brotherton, I tried a bottle of Lubegard to deal with a flaring problem in my auto trans between the 2 forward gears. Miraculously the flaring problem is now gone and the trans now shifts with decisive but not neck-snapping shifts. I used to only apply half throttle to avoid the flaring in the lower gears, but now I can sock the whole 77 hp to the trans with no flaring.

I can't be abolutely certain that the Lubegard solely corrected the flaring problem, but over the 3 month trial period, I haven't touched a thing on the trans area.

Gary

'79 300D
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  #26  
Old 08-13-2001, 08:25 PM
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Which lubegard product do you use. I went to their website and they have lots of products that all seem the same to me. My 1982 280e shifts late and shifts hard (neck snap variety).
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  #27  
Old 08-14-2001, 06:20 PM
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Sorry, I should have mentioned that the product I used was the stuff in the red plastic bottle called "LUBEGARD® ATF PROTECTANT".

deeph8,
Maybe your trans has something wrong with the modulator adjustment, (I don't have a clue about them). I found out on this thread that my car, a diesel doesn't have one so I tried the Lubegard.
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  #28  
Old 08-17-2001, 09:23 AM
N. Gilbert
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Transmission Flaring

AV, could you please describe what flaring means? I have a 92 300E that is shifting hard between first and second. I would like to follow the same path that you did to fix your problems.
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  #29  
Old 08-17-2001, 09:46 AM
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Location: Gainesville FL
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There has been much writen on flaring, be sure to check the archives.

Flaring and harsh shifting are at opposite ends of the shift condition. Flaring refers to the increase in rpms which occurs during delays in proper shift overlap. Shifting in many cases requires the activation of one element after the release of another. Because these activities are not instantaneous the timing of these events requires the added element to start before the released element. Shift pressure (as affected by modulator pressure) is the only external way to affect the timing relationship (more pressure shortens all timing intervals).

The reason flaring comes about and the reason lubeguard helps is twofold. The amount of leakage from the seals of activating elements (clutch drums/band servos) is a great contributor to disturbing timing. The lubeguard type products softens seals and reduces internal leakage. The product also is a friction enhancer which alows older discs to effectively engage quicker.

Unfortunately the results of such products may be short lived. In the case of the early diesel (without modulator) I would suggest shortening the control linkage (delays shifts and increases shift pressure).. For those with modulators I would increase the pressure by a turn and go from there.

For those with harsh shifts, I would reduce modulator pressure as long as ALL shifts are firm.
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  #30  
Old 08-21-2001, 10:04 AM
N. Gilbert
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Thank you stevebfl. I understand the difference now. I believe that modulator adjustment (back-off one turn) will be my initial starting point.
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