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  #1  
Old 05-08-2007, 06:59 AM
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Hard Shifting Transmission 83 300D

I just bought an 83 300D Turbo Diesel from the original owner with 201k miles. I was told the transmission was rebuilt a while ago and since that time it shifts very hard from 1st to 2nd gear. The other shift points seem smooth, but possible too soon. Any ideas? So far, I love the car. It runs great, but is a little sluggish. KRW

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Old 05-08-2007, 09:43 AM
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I have an 83 300d with the same problem. I disconnected the vacuum control valve, on top of the valve cover gasket, and plugged off the lines and the 1-2 shift is MUCH better. I am thinking that I have a vacuum leak in the plugged off line somewhere. Now I need to find out what all I just disconnected. I would love to just leave it all unplugged.

Before it felt more like I have been rear ended than a 1-2 shift. Now it's like it should be, firm but right for this stodgy old car.


Jackson
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Old 05-08-2007, 12:08 PM
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Quote:
Originally Posted by krwsenior View Post
I just bought an 83 300D Turbo Diesel from the original owner with 201k miles. I was told the transmission was rebuilt a while ago and since that time it shifts very hard from 1st to 2nd gear. The other shift points seem smooth, but possible too soon. Any ideas? So far, I love the car. It runs great, but is a little sluggish. KRW
The harshness of the shift is controlled by the vacuum from the vacuum control valve to the modulator. The more vacuum.........the softer the shifts.

The '83 is noted for a very firm 1-2 shift. It's possible to soften it slightly, but, you risk flaring on the 2-3. If you wish to attempt it, you'll need a Mityvac to perform the adjustment. If you get one.......just return and post and we'll help you with it.

If the shifts are too early, you can adjust the Bowden cable under the hood for that. It's attached to the throttle linkage near the back of the head. Look for a cable and a rubber dust boot. Find the plastic adjustment nut on the opposite side of the bracket and turn the nut counterclockwise three turns to tighten the cable. Take it for a drive and see if you like the later shift points.
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Old 05-08-2007, 12:14 PM
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You came to the right place. I have a similar car and had similar questions. The guys on this forum have taken me from total ignorance of how this system operates to a pretty fair understanding. Hence a much smoother shifting car and that wonderful feeling of "I understand how this thing works" Hang in there - you have found the mother lode of help.
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Old 05-08-2007, 12:20 PM
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Originally Posted by Jaclson View Post
I have an 83 300d with the same problem. I disconnected the vacuum control valve, on top of the valve cover gasket, and plugged off the lines and the 1-2 shift is MUCH better. I am thinking that I have a vacuum leak in the plugged off line somewhere. Now I need to find out what all I just disconnected. I would love to just leave it all unplugged.

Before it felt more like I have been rear ended than a 1-2 shift. Now it's like it should be, firm but right for this stodgy old car.


Jackson
I'm guessing that you disconnected the black box on top of the valve cover..........and you did not disconnect the vacuum control valve.

The black box controls the EGR and is responsible for many vacuum leaks in the system........resulting in too little vacuum to the modulator.

You can remove all the lines to and from the black box and plug the T's where the lines terminate. Actually, you can remove the T's completely and connect the remaining Tecalan lines with a short piece of hose.

The line from the vacuum control valve to the transmission must remain in place.......and functional........if the shift quality is to be sufficiently soft.
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  #6  
Old 05-08-2007, 12:54 PM
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Wow! Great information.

Thank you very much. I have several ideas to look at now. KRW
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  #7  
Old 07-30-2013, 10:21 PM
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Quote:
Originally Posted by krwsenior View Post
I just bought an 83 300D Turbo Diesel from the original owner with 201k miles. I was told the transmission was rebuilt a while ago and since that time it shifts very hard from 1st to 2nd gear. The other shift points seem smooth, but possible too soon. Any ideas? So far, I love the car. It runs great, but is a little sluggish. KRW
I just got one of the same last week and one today. The first one is for a diesel conversion on my Disco I and the other one I got today for ridiculously cheap so I am going to re condition some little thinks and flip it. Learning along the way of course.

Sluggish may be result of the throttle linkage / rocker on the fire wall. If that is with little play, I would look to obvious fuel flow and air flow. after that, consider checking emissions deposit on waste site of turbo located under the air intake housing where the air filter is. Also check for BOOST leak. This is all without asking you to explain the sluggish symptom in detail. eg slow to boost less than reactive throttle... etc

I am new here but not a total noob. I don't know everything but i am no slouch.

Cheers

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