89PalermoSHP Posted July 10, 2011 Report Share Posted July 10, 2011 I didn't see a topic covering this part, please post a link if I just over looked it. I just got my transmission rebuilt and the car is up and running. I took it for a couple quick rides and noticed the shift timing seems a bit off. It will downshift and upshift just a bit quirky if there are sudden speed changes. I know the modulator was replaced with a new adjustable unit. I cant say with 100% certainty its correct one since I did not buy the part, the shop did. 1. Does the shifting issue seem like it could be from that needing a bit of adjustment? 2. I measured my old one and I believe it looks smaller than whats on there. I see Napa has 2 listed and my original matches the smaller of the two. 3. How do you adjust the thing? 4. If I decide to replace it with the Napa one, can I remove it w/o a/t fluid spilling everywhere? Thanks Link to comment Share on other sites More sharing options...
Indiana Posted July 10, 2011 Report Share Posted July 10, 2011 I believe its the boost that "adjusts" them and it must have the turbo modulator or it will burn up. Link to comment Share on other sites More sharing options...
89PalermoSHP Posted July 11, 2011 Author Report Share Posted July 11, 2011 https://napaonline.com/Catalog/Result.aspx?Ne=25000&Ntt=&Nty=1&N=599001+101989+50016+2016001+27990&Ntk=Keyword Since they are both listed for the Conquest, do we assume its meant for turbo? The second one is the one that looks like what came off the transmission. I should be able to replace without draining correct? Link to comment Share on other sites More sharing options...
Indiana Posted July 11, 2011 Report Share Posted July 11, 2011 I think the smaller ones are for turbo but I also thought there was a difference in the rod lenght too. According to the parts manual, there are 5 different length rods and you can get the modulator from the dealer still if in doubt. Some sites say to only use a genuine Jatco modulator not an aftermarket remember the modulator is like the fuel pressure regulator in your throttlebody its very important. As to which rod to use I don't know I'd have to read the service manual why there is a difference. Link to comment Share on other sites More sharing options...
89PalermoSHP Posted July 11, 2011 Author Report Share Posted July 11, 2011 I was under the impression the adjustable one eliminated the need for the rods. If I recall, you were to measure a distance possibly after installation and get the corresponding rod. I need to reread the section on that. The oem unit was $40 or so, probably $50 from the local dealer. Link to comment Share on other sites More sharing options...
89PalermoSHP Posted July 12, 2011 Author Report Share Posted July 12, 2011 The OEM one is NLA so I'm going to go with the Napa one listed with a 1 1/4" diaphragm. I'm not positive what was on my transmission was original but it shifted better than whats on there now. Link to comment Share on other sites More sharing options...
Indiana Posted July 13, 2011 Report Share Posted July 13, 2011 The rod is the physical connection from the diaphragm in the modulator to the throttle control valve in the valve body. http://a8.sphotos.ak.fbcdn.net/hphotos-ak-snc6/281522_1447923616266_1778479606_705851_1685682_n.jpg http://www.eng.fsu.edu/~jthagard/4n71b/4n71b-1.jpg http://www.eng.fsu.edu/~jthagard/4n71b/4n71b-2.jpghttp://www.eng.fsu.edu/~jthagard/4n71b/4n71b-3.jpg Link to comment Share on other sites More sharing options...
Alan Posted July 13, 2011 Report Share Posted July 13, 2011 When I did mine last year, I used the NAPA adjustable modulator. You will still need the pin, as Indiana says. I used the original. I figured adjusting the modulator would make up for trying the different lenghts or rods. If I remember correctly I adjusted mine almost full counterclockwise(left) to get the shifts matching the FSM spec's(speed). I had read that these can only be adjusted to change the shift points about 5 mph at most. It seemed to me that from full CCW to CW was more than that. And thanks to Indiana for posting the mod for the vb, something I plan to do further down the road(along with about 50 other things!). Link to comment Share on other sites More sharing options...
89PalermoSHP Posted July 14, 2011 Author Report Share Posted July 14, 2011 Thanks for the info guys. Hopefully it can get worked out this weekend. Link to comment Share on other sites More sharing options...
Indiana Posted July 14, 2011 Report Share Posted July 14, 2011 something I plan to do further down the roadIts a Nissan made transmission the common name is 4N71B or without the overdrive unit which I don't know if anyone ever deleted or changed to in a Starion but then its a 3N71B. Its from the 70s and very common. If you're searching for mods you'll find most on Z car forums since they also use it or cars in Austrailia. Link to comment Share on other sites More sharing options...
89PalermoSHP Posted July 14, 2011 Author Report Share Posted July 14, 2011 Ok, I just spoke with the rebuilder and since the shifts were a bit soft I remembered him saying something about the valve body. He said there were 4 possible spaces for check balls but only 2 of them contained the parts. Is this correct? I also got the modulator from napa and hope to install it tonight. Link to comment Share on other sites More sharing options...
Indiana Posted July 16, 2011 Report Share Posted July 16, 2011 There's a TSB for that as well... Makes you wonder where he put them hopefully in the correct two holes. http://www.b2600turbo.com/images/TSBvb01.jpghttp://www.b2600turbo.com/images/TSBvb02.jpghttp://www.b2600turbo.com/images/TSBvb03.jpghttp://www.b2600turbo.com/images/TSBvb04.jpghttp://www.b2600turbo.com/images/TSBvb05.jpghttp://www.b2600turbo.com/images/TSBvb06.jpg Link to comment Share on other sites More sharing options...
Alan Posted July 20, 2011 Report Share Posted July 20, 2011 I owe you a measurement! My fault,you will have tomorrow. Alan Link to comment Share on other sites More sharing options...
89PalermoSHP Posted July 20, 2011 Author Report Share Posted July 20, 2011 No hurry, I wont get to it till Friday at the earliest. Link to comment Share on other sites More sharing options...
Alan Posted August 2, 2011 Report Share Posted August 2, 2011 The one I have is the smaller of the 2 at NAPA. When I got mine they listed one as non adjustable and one as adjustable. Looks like that has changed now. Link to comment Share on other sites More sharing options...
89PalermoSHP Posted August 7, 2011 Author Report Share Posted August 7, 2011 3 modulators later I think I've got it figured out. I ordered the "turbo" specific modulator from Transmission Parts USA and its works like a charm right out of the box. I'm not sure if its adjustable or not but the shifts are perfect. It was about $33 shipped. http://www.transmissionpartsusa.com/Nissan_L3N71B_L4N71B_Turbo_modulator_1971_on_p/820-000082885.htm Link to comment Share on other sites More sharing options...
Alan Posted August 7, 2011 Report Share Posted August 7, 2011 Great! I might pick one up and see if there is any difference. Glad it's going! Link to comment Share on other sites More sharing options...
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