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  #16  
Old 04-04-2006, 10:15 PM
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update

I really doubt anybody will read through this whole thing, but if so:

I tried disconnecting the vacuum hose to the tranny and took it for a spin. The shifts seemed a little more sloppy/slappy/harsh. It WOULD downshift into third when I told it to, i.e. coasting and dropping the lever. But it would NOT downshift into second unless I pushed on the old pedal.

Regardless of whether the hose was connected or not, If I start out in 2, it will not up shift into 2 until I throw it into 3. If I immediately downshift back into 2, it will stay in 2. I don't know if this is related at all, but it's info.

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  #17  
Old 04-04-2006, 10:31 PM
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Just for the hell of it, attempt to take up some slack in the Bowden cable. Turn the plastic piece two or three turns and reinsert it. Drive it again and see if the additonal tension in the cable makes any difference.

Remember, when you press on the pedal and the transmission behaves, the cable is moving..............
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  #18  
Old 04-05-2006, 10:43 AM
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Quote:
Originally Posted by Brian Carlton
Just for the hell of it, attempt to take up some slack in the Bowden cable. Turn the plastic piece two or three turns and reinsert it. Drive it again and see if the additonal tension in the cable makes any difference.

Remember, when you press on the pedal and the transmission behaves, the cable is moving..............
No effect on the downshift.

If the transmission seems to work "fine" without the vacuum, what is the point of the vacuum? I guess it does smooth my shift out. Would it be bad to run the transmission without vacuum? I'm thinking of if I do happen to be in the mountains and I really want to be able to downshift, I could yank the vacuum. Hopefully I'll have it fixed before that occurs.
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  #19  
Old 04-05-2006, 11:45 AM
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Quote:
Originally Posted by bbeardb
No effect on the downshift.

If the transmission seems to work "fine" without the vacuum, what is the point of the vacuum? I guess it does smooth my shift out. Would it be bad to run the transmission without vacuum? I'm thinking of if I do happen to be in the mountains and I really want to be able to downshift, I could yank the vacuum. Hopefully I'll have it fixed before that occurs.
So, without vacuum connected to the modulator, the transmission will downshift properly??

This is rather strange. The vacuum will typically slow the onset of the shift, and thereby "soften it". But, for it to delay or prevent a downshift is certainly unique.
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  #20  
Old 04-05-2006, 12:23 PM
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Quote:
Originally Posted by Brian Carlton
So, without vacuum connected to the modulator, the transmission will downshift properly??

This is rather strange. The vacuum will typically slow the onset of the shift, and thereby "soften it". But, for it to delay or prevent a downshift is certainly unique.
That is correct. Without vacuum (unless there is another line I'm not seeing), it will downshift while coasting and I go from D to 3. It will not do this when the vacuum line is connected.
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  #21  
Old 04-05-2006, 12:26 PM
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Quote:
Originally Posted by bbeardb
That is correct. Without vacuum (unless there is another line I'm not seeing), it will downshift while coasting and I go from D to 3. It will not do this when the vacuum line is connected.
Can you T a vacuum gauge into the line to the transmission and route the gauge into the cabin? Then take it for a drive, with the line connected, and report back on the vacuum readings at various speeds/loads.

I'm curious as to the vacuum at idle and at about 1/2 pedal, and at full pedal.
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  #22  
Old 04-05-2006, 12:36 PM
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Quote:
Originally Posted by Brian Carlton
Can you T a vacuum gauge into the line to the transmission and route the gauge into the cabin? Then take it for a drive, with the line connected, and report back on the vacuum readings at various speeds/loads.

I'm curious as to the vacuum at idle and at about 1/2 pedal, and at full pedal.
I'll have to buy a guage. Any recommendations, or whatever the local parts place has? The finger guage says I can feel suction at idle, but not hickey inducing suction.
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  #23  
Old 04-05-2006, 12:44 PM
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You know, I just thought of something. At some point in time, don't remember when, I disonnected all the EGR stuff. I know it shouldn't, but I wonder if that had an affect at all.
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  #24  
Old 04-05-2006, 12:46 PM
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Quote:
Originally Posted by bbeardb
You know, I just thought of something. At some point in time, don't remember when, I disonnected all the EGR stuff. I know it shouldn't, but I wonder if that had an affect at all.
Don't even start second guessing yourself regarding disconnecting the EGR.

I have all lines disconnected and removed from the black box and the SD shifts perfectly. Note, however, that I reduced transmission vacuum at idle from 12" down to 8". I'm right at the edge of clunking on downshifts........in fact.........I'll get a downshift clunk when the transmission is cold. But, all the upshifts are firm but not harsh.
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  #25  
Old 04-05-2006, 12:48 PM
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Quote:
Originally Posted by bbeardb
I'll have to buy a guage. Any recommendations, or whatever the local parts place has? The finger guage says I can feel suction at idle, but not hickey inducing suction.
You can use a mityvac if you have one.

If you don't have one.........by now..........I'd be surprised...........
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  #26  
Old 04-05-2006, 01:01 PM
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Quote:
Originally Posted by Brian Carlton
You can use a mityvac if you have one.

If you don't have one.........by now..........I'd be surprised...........
Hey, It's been winter. The car has been sitting in my garage pretty much the whole time. But spring is here and I want to get this thing to original operating condition. Well, at least the tranny so I can do some mountian runs. Other things I need to do are, replace left rear window clip, re-solder cruise amp, fix driver foot vent, and get my cooling system under control. That's it. Well, except for my 20 second 0-60. I thought it was running great, but I guess that's not great. Diesel purge is next. All pretty easy I think, compared to the shifting mystery. And none of it (except tranny) has to do with vacuum (or so I think.)
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  #27  
Old 04-05-2006, 01:12 PM
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Quote:
Originally Posted by bbeardb
Well, except for my 20 second 0-60. I thought it was running great, but I guess that's not great. Diesel purge is next.
Purge won't solve a 20 second 0-60 time.

You're not getting any pressure to the ALDA..........or..........less likely.........the turbo is not making any boost.

.......banjo bolt.......line to overboost valve.......overboost valve itself........line to ALDA.........banjo bolt at ALDA...........all must be thoroughly cleaned or replaced.

I got a cheap G-tech Pro on e-bay and will accurately check the SD soon. I'm thinking it will be in the 14 second range.
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  #28  
Old 04-05-2006, 01:17 PM
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Quote:
Originally Posted by Brian Carlton
Purge won't solve a 20 second 0-60 time.

You're not getting any pressure to the ALDA..........or..........less likely.........the turbo is not making any boost.

.......banjo bolt.......line to overboost valve.......overboost valve itself........line to ALDA.........banjo bolt at ALDA...........all must be thoroughly cleaned or replaced.

I got a cheap G-tech Pro on e-bay and will accurately check the SD soon. I'm thinking it will be in the 14 second range.
Tubo is working, I can feel it, I can get tires to chirp on 1-2 shift. I am a mile high, which doesn't help. All lines and banjo bolts are clean. Don't know what the overboost valve is. I posted a pic in the name these parts thread about a turbo line which I don't know what it is. But now we are way off topic. Perhaps PM or new thread is in order.

Edit: Also, adjusting the ALDA does have an effect. I did turn it down a little becuase I'd rather have less smoke than a barely perceptable increase in acceleration. Perhaps I have it at the sweet spot right now, or perhaps I should go adjusting away again and see if I can pump up my times, but I don't think so.
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Last edited by bbeardb; 04-05-2006 at 01:28 PM.
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  #29  
Old 04-05-2006, 08:06 PM
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Tran maintenance

Relative to more recent MB products, re, '97 C280. Have 200 K miles on my Benz and dealer along with owners manual advises that trans fluid no longer needs to be changed. Forever. Never. My experience, trans works as good as when vehicle was new! Go figure. Comments?
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  #30  
Old 04-06-2006, 10:58 AM
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Quote:
Originally Posted by Peter Fearing
Relative to more recent MB products, re, '97 C280. Have 200 K miles on my Benz and dealer along with owners manual advises that trans fluid no longer needs to be changed. Forever. Never. My experience, trans works as good as when vehicle was new! Go figure. Comments?
Maybe they don't think the car will last much longer! Just kidding, but I think they are crazy. Why would you need to change it for the first 200K, but never again after that? Do they achieve perfect status or something? If so, they should do a burn on all transmissions before they go in cars. Just hook them up and run them non stop for 6 months or so before they install them in a car. Like aged wine or something.

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