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hesitation shifting 3rd-4th at low rpm
Hello
Lately the transmission is hesitating between 3rd and 4th in low rpm (2000-2500) This means driving up to 50-55 mph. When adding gas rpm rise very quickly up to 3000 without shifting back. When pullling harder 3000-4000 rpm no problem shifting at all As I read a lot here, could it be the brakeband? Thanks for your input Rinus Slippens The Netherlands 1992 251000 km blue |
#2
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Re: hesitation shifting 3rd-4th at low rpm
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If it slips going into 2nd it is. If it does not slip in 2nd, then it is probably low line pressure that is causing it to slip in 3rd/4th, so that it goes back to 3rd, and then back to 4th, that is low line pressure. 4th gear is 3rd gear + the band, when it slips, your back in 3rd. At the higher rpms the line pressure is high enough to hold. Harvey.
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One Arm Bloke. Tell it like it is! 95 Lsi. Bordeaux Pearl, Aust. RHD.149,000Kls Subaru BBS wheels. 97 Liberty GX Auto sedan. 320,000Kls. 04 Liberty 30R Auto Premium. 92.000kls. |
#3
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Re: hesitation shifting 3rd-4th at low rpm
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how can I determine if my car slips in second? Is it possible to increase line pressure? (line pressure= hydraulic pressure?) thanks. |
#4
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Re: hesitation shifting 3rd-4th at low rpm
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#5
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Re: hesitation shifting 3rd-4th at low rpm
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The band is used to hold the front sun gear still in 1st and 4th. In 1st the forward clutch is on, for 2nd the band comes on also. If the band is worn, and is slipping, you will find that it will change into 2nd at a higher rpm. The same thing happens for 4th. When it goes from 2nd to 3rd, the band has to be released, and the high clutch has to be applied, at the same time. If the band is worn, it will release before the high clutch comes on, so the box goes back to 1st and revs till the high clutch grips, this is called “flaring”. This is when adjusting the band can help. The 3rd to 4th change has the high clutch on for 3rd, and the band is applied also to raise the gearing for 4th. This is when the band can loose pressure and slip, and the box goes back to 3rd. This usually happens when you are driving slow in 4th with the engine reving about 1500 to, 2500. The low engine rpms that drive the pump is too slow, and the pumps flow will be too low, to provide good line pressure, so the band slips, it goes back to 3rd, this lets the engine rev higher, the line pressure comes back up, and the band grips to goes back to 4th. I believe this is Rinus’s problem. This is really a case of a box that is draining too much oil due to wear, and will burn the band up if it continues. It is better to drive in 3rd at low speeds to keep the line pressure up and the load on the box low. Harvey.
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One Arm Bloke. Tell it like it is! 95 Lsi. Bordeaux Pearl, Aust. RHD.149,000Kls Subaru BBS wheels. 97 Liberty GX Auto sedan. 320,000Kls. 04 Liberty 30R Auto Premium. 92.000kls. |
#6
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Re: hesitation shifting 3rd-4th at low rpm
Thanks a lot everyone, could adjustment of the brakeband be a solution?
Rinus |
#7
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Re: hesitation shifting 3rd-4th at low rpm
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If you unplug the dropping resistor, behind the battery, it will raise the line pressure to max, if this stops the random changing, then it is the low line pressure that is the cause. You might check the setting of the Throttle Position Sensor, to ensure it is set to 0.5V, and its readings are smooth through the sensor movement. If it has some worn spots, it will cause the box to change when it gets to a bad spot. And drive in 3rd around town. Harvey.
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One Arm Bloke. Tell it like it is! 95 Lsi. Bordeaux Pearl, Aust. RHD.149,000Kls Subaru BBS wheels. 97 Liberty GX Auto sedan. 320,000Kls. 04 Liberty 30R Auto Premium. 92.000kls. |
#8
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Re: hesitation shifting 3rd-4th at low rpm
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Jared 1992 dark teal SVX LS |
#9
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Re: hesitation shifting 3rd-4th at low rpm
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The car is designed to do 150 mph in 4th, so asking it to do 35-40mph is asking a lot. It's not that the car can't do it, the low speed torque is strong enough to do it, but due to the load on the band, and low line pressure, it will eventually die. I make a point of 3rd till I am running 100kph/62mph, then 4th. Harvey.
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One Arm Bloke. Tell it like it is! 95 Lsi. Bordeaux Pearl, Aust. RHD.149,000Kls Subaru BBS wheels. 97 Liberty GX Auto sedan. 320,000Kls. 04 Liberty 30R Auto Premium. 92.000kls. |
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