why adjust transmission bands?
#1
why adjust transmission bands?
what is the purpose of adjusting the bands? can you adjust the front and not adjust the rear? or do you need to do them both at the same time? im new to dodge rams, but im familiar with the engines. i just got rid of my jeep grand cherokee that had the 318 engine in it if i remember right, the jeep guys kept saying the same thing about adjusting the bands.
the reason im asking is because my transmission shifts fine, but it is really smooth and quick to shift. i tried adjusting the tv cable and that didnt help at all. i know in the jeep i had the transmission was a 46rh also and it shifted really firm.
by the way im working on a 1994 ram 4x4 with a 360 engine. thanks for the input
the reason im asking is because my transmission shifts fine, but it is really smooth and quick to shift. i tried adjusting the tv cable and that didnt help at all. i know in the jeep i had the transmission was a 46rh also and it shifted really firm.
by the way im working on a 1994 ram 4x4 with a 360 engine. thanks for the input
#7
Oops-sorry
Smooth shifts are what an automatic is supposed to do but doesn't always achieve. To quote an old mechanic friend of mine: If it ain't broke don't fix it.
To answer your question though. If the bands are too loose they will slip, if they are too tight the will destroy themselves. That is why this adjustment needs to be done properly.
Preventive maintenance such as adjusting bands should not be needed unless: 1. the vehicle sees rough service such as snow plowing or heavy load hauling on a regular basis, 2. extremely high milage, 3. actual slippage or other erratic shifting problems.
Most Chrysler trannys that have bands and not clutch packs use one band for reverse and low, and another for the front (kickdown / upshift). If you experience slippage I would recommend adjusting both bands as this is not rocket science, but the problem will almost always be in the low reverse band.
Here is an explanation of the clunk many of us feel when we shift into reverse. It is a little technical but I found it interesting.
There is a definite reason for the famous "Clunk" when the rear wheel drive vehicles are put into Reverse. It is designed in. When put into Reverse, an entire different hydraulic circuitry is used and the line pressure will flow to a different part of the Regulator Valve which causes the line pressure to rise. This line pressure is directed to the Low / Reverse Servo and the Front Clutch. The need for higher pressures is due to the design features of each clutch assembly. Both clutches are applied by hydraulic force and the Rear clutch utilizes a Bellville Spring, which multiplies this force. This multiplied, higher force pushes against eight mechanical levers to assure a firm application of the band without slippage. Rear Clutch pressure here can rise to 270 psi - they deem necessary to prevent slippage. The other, forward circuit design does not have this pressure range to control those shift points. The front cluch, in this circuit does not require this higher pressure because it is used only in the upshift to Drive, and since the car is already under way, there is no likelihood that there will be any slippage here. Chrysler tried to reduce this shock somewhat, but they didn't want to revise the whole thing. If you look at a cross section of the Low / Reverse Servo, you'll see the spring cushoning the piston travel as it applies the band; This lever has the Low / Reverse Band adjustment on its' end. If you loosen the adjustment to reduce the shock, the shock will become more harsh, this adjustment is not recommended. There is one aid a Chrysler dealer recommended to me, he said that they modified the circuit flow rate by adding a small Cotter Pin into the hole for this circuit in the valve body. What this did was to delay the pressure build-up , not eliminate it, but build it up slowly, and they had many happy owners with no more complaints.
I hope this helps.
Smooth shifts are what an automatic is supposed to do but doesn't always achieve. To quote an old mechanic friend of mine: If it ain't broke don't fix it.
To answer your question though. If the bands are too loose they will slip, if they are too tight the will destroy themselves. That is why this adjustment needs to be done properly.
Preventive maintenance such as adjusting bands should not be needed unless: 1. the vehicle sees rough service such as snow plowing or heavy load hauling on a regular basis, 2. extremely high milage, 3. actual slippage or other erratic shifting problems.
Most Chrysler trannys that have bands and not clutch packs use one band for reverse and low, and another for the front (kickdown / upshift). If you experience slippage I would recommend adjusting both bands as this is not rocket science, but the problem will almost always be in the low reverse band.
Here is an explanation of the clunk many of us feel when we shift into reverse. It is a little technical but I found it interesting.
There is a definite reason for the famous "Clunk" when the rear wheel drive vehicles are put into Reverse. It is designed in. When put into Reverse, an entire different hydraulic circuitry is used and the line pressure will flow to a different part of the Regulator Valve which causes the line pressure to rise. This line pressure is directed to the Low / Reverse Servo and the Front Clutch. The need for higher pressures is due to the design features of each clutch assembly. Both clutches are applied by hydraulic force and the Rear clutch utilizes a Bellville Spring, which multiplies this force. This multiplied, higher force pushes against eight mechanical levers to assure a firm application of the band without slippage. Rear Clutch pressure here can rise to 270 psi - they deem necessary to prevent slippage. The other, forward circuit design does not have this pressure range to control those shift points. The front cluch, in this circuit does not require this higher pressure because it is used only in the upshift to Drive, and since the car is already under way, there is no likelihood that there will be any slippage here. Chrysler tried to reduce this shock somewhat, but they didn't want to revise the whole thing. If you look at a cross section of the Low / Reverse Servo, you'll see the spring cushoning the piston travel as it applies the band; This lever has the Low / Reverse Band adjustment on its' end. If you loosen the adjustment to reduce the shock, the shock will become more harsh, this adjustment is not recommended. There is one aid a Chrysler dealer recommended to me, he said that they modified the circuit flow rate by adding a small Cotter Pin into the hole for this circuit in the valve body. What this did was to delay the pressure build-up , not eliminate it, but build it up slowly, and they had many happy owners with no more complaints.
I hope this helps.
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#8
#9
Personally, I say leave the bands alone. I have seen many people on here get under there and play with them, and then the tranny will fail about a week after that. If you were slipping or something like that, I still say leave it the hell alone. I have seen these trucks go for another 15-20K miles on a tranny that is starting to slip. Compare that to the people that crawl under there and do an adjustment and then they end up getting their tranny rebuilt less than a 1000 miles later....
Just a thought.
Just a thought.