phantom transmission

[carfrk666]

i have a 90Q that ive been doing quite a bit of work on, tryin to do a full restoration and get some serious power to it so im planning things out with it on what i want to do, every place i go it says that it has a 4 speed auto, all places say this, however say im going up a hill, under some load, i put the transmission into manual 3rd, drive for a bit then put it back into drive, it upsifts into 4th and then another second after that, it upsifts into another gear again, when i found this out i couldnt belive it and i did it several times and it always seems like i have a 5th gear and ive noticed it while regular driving, am i just crazy or is suttin sounding not stock here? please tell me im crazy cause i would love to have a 5 speed

[captainluigi]

i think you may be feeling the torque converter lock-up. do you see a decrease in rpm,s when it goes into that phantom 5th gear?

[Q45tech]

One must read the 201 pages in FSM AT section about 10 times to begin to comprehend the RE4R03A transmission.

[carfrk666]

ya i do see a drop in RMPs which is why i know its goin into another gear, phantom 5th, and as far as i know that transmission is stock, i mean when i took out the engine to rebuild it the transmission bolts must have been torqued to like 200lb because i could hardly break them loose so i doubt if the transmission was aftermarket or something that they would torque them that tight again, and where would i find this document for the transmission? the one explaning it and how it works?

[ceningolmo]

Dennis... I read about 2.5 pages of it once. It hurt my brain so I went and played golf instead. Should I assume that I shouldn't perform my own transmission overhaul when the time comes?

[Q45tech]

4 forward gears plus lock up convertor clutch in 3rd and 4th.

Dream on.

[ceningolmo]

I suspected as much. I'm glad I played golf instead.

I think I'll just buy a Nissan reman unit when the time comes.

[carfrk666]

what do u mean a clutch lockup on 3rd and 4th? because im at about 2500 rpms when this all happens, so thats way over converter lockup, and if that is converter lockup then it is really hard

[Q45tech]

4th gear lockup - unlock can occur betwen 35 and 95 mph under less than 1/8 throttle opening and up to 122 mph at 7/8 throttle opening.

That would/could be between 1200 rpm and 4,000 rpm

All things fully desribed by the graphs on page AT 31 in your FSM.

"Because slip within the torque converter reduces efficiency and may generate excessive heat, some converters incorporate a lockup mechanism: a mechanical clutch that engages at cruising speeds to physically link the impeller with the turbine, causing them to rotate at the same speed with no slippage.

The first automotive application of the lock-up principle was Packard's Ultramatic transmission, introduced in 1949, which locked up the converter at cruising speeds, unlocking when the throttle was floored for quick acceleration. The demand for increased automobile fuel economy brought about a gradual but widespread application of the lock-up converter for automotive transmissions between the late 1970s and mid-1980s."http://en.wikipedia.org/wiki/Torque_converter

[Jeff Williams]

IT is normal to feel the lock and unlock of the TC, if you are sensitive to it. I can really tell, now that I have a more free flowing exhaust. I can hear it lock and unlock. It is worth about 100 to 200 RPM drop when it locks.

I spent about 4 hours in the transmission section of the FSM. It is very toublesome to read if you don;t have a transmission to play with, or have never been into one before.

I have a book on my 1962 GMC transmission. It is well written and easy to understand.

Here is a great site for TC information.

http://www.converter.cc/faq/faq_main.htm

[carfrk666]

so would this clutch unlock make the RPMS go down from about 2500 to 2000 under load up a hill?

[carfrk666]

however my Rpms drop about 500 and it is very signifigent, my Q is pretty much stock and when it does this phantem gear it feels just like a shift and is very hard