ishnish Posted March 25, 2016 Report Share Posted March 25, 2016 Hey guys so I've encountered a problem with my datsun b210 just recently. Ever since my dad replaced the head on the car it's been running great except for one thing: the transmission shifts noticeably later. I've checked the transmission fluid and it's still bright red, I've also checked the kickdown switch by the gas pedal just in case and that was adjusted fine I think (it clicks when gas is completely floored). I don't think the transmission filter has been changed and I've read that it could possibly be the modulator as well but these are on general articles not datsun specific so I just need to be sure. Anyone know what the possible solution could be for this? And just as a side note and fyi, it's a 3 spd auto and it shifts from 2nd to 3rd gear around the 40 mph. The engine is screaming at that point I feel. I definitely don't want a new head to already go bad after all that money. Thanks guys Quote Link to comment
datzenmike Posted March 25, 2016 Report Share Posted March 25, 2016 Ok first it will go 60 in second when passing so don't worry you won't hurt a thing. Now the problem... Look on the intake on or near the large vacuum hose for the brake booster. There will be a very small fitting sticking out that should have a small rubber hose on it connected to a metal hard line that goes down behind the engine to the transmission's modulator valve. The modulator valve uses engine vacuum to tell it how hard you are driving the engine. High vacuum would be idle or very light throttle just tooling around town. Low vacuum means you have the throttle floored and may be passing a car or on an on ramp to the highway. A low vacuum signal tells the transmission not to up shift too soon and allow the engine to make some power. If this vacuum line is off the transmission will be fooled into thinking that you have the throttle to the floor at all times and will delay the up shift. Here's my vacuum line on my 710 sedan. Yours will be somewhat similar or may be a separate little fitting. Follow the booster hose across the top to the left and down to the fitting on the intake. That fitting also has a smaller line coming out towards you. A short hose connects it to a metal line that goes down behind the engine. Maybe find this line and follow it up the the intake.. Quote Link to comment
MikeRL411 Posted March 26, 2016 Report Share Posted March 26, 2016 And I was just about to wise ass "If you Granny shifts late, buy her an automatic transmission car." Quote Link to comment
ishnish Posted March 26, 2016 Author Report Share Posted March 26, 2016 Datzenmike, thank you for the very detailed info and picture. If I find the line, what could I do to adjust the vacuum pressure to something higher so it can shift on time? Also, I'm not sure if this has anything to do with it or helps but I noticed a while ago Every time I hit the breaks, I hear a high-pitched sound almost like a leaky line probably because I have spongy breaks. Now though, it happens the entire time I drive the car and when I hit the brakes it gets louder. Do you think this has anything to do with the transmission as well? Probably not but I figure it doesn't hurt to mention it. Quote Link to comment
ishnish Posted March 26, 2016 Author Report Share Posted March 26, 2016 UPDATE Datzenmike, I couldn't find any hardline by the brakebooster so I tried to find the hardline coming front the tranny. I ended up finding one and it led to the back of the intake just as you stated and it was disconnected! I found the rubber hose that was supposed to be connected to it and so connected it back and WALLAH! Took my car for a test drive and it shifts perfectly now! Thank you very much you have no idea the amount of money you saved me! Quote Link to comment
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