Imperial Transmission Bands & How To Adjust Them

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Question from Neil (1982):

I was thinking of changing the transmission oil and filter on my '82 imp, while doing this I will maybe adjust the bands especially the low reverse band due to the usual harsh engagement when selecting reverse.

Idle speed is correct.

Question: will adjustment make the harsh engagement better or am i stirring up a hornets nest????


From Philippe:

Beware of band adjustements! On old torqueflites, the reverse band is also used in "D" gear so you could disturb the good functionnement of your transmission. If you loosen the band you'll have slippage or no engagement of reverse and Drive. If adjustement is too tight, you'll ruin the band.

To adjust the bands you must follow the method in the FSM: loosen the locknut, back off the adjustment screw, tighten to specific torque and back off a specific number of turns (see FSM).

I've also removed the power train from the transmission without removing the transmission case. You don't have to remove the starter, converter, oil cooler lines and the HEAVY transmission assembly. It's easier and faster. But you must be sure that the front pump and regulator valve body are clean and that the front pump oil seal isn't worn!

From Rick:

I've had early cast iron transmissions with broken reverse bands and the rest of the performance was fine. The most recent one was a '60 Chrysler with a 383. No reverse and a broken band. I replaced the band with no other changes. It corrected the problem. That was 2 years ago and it still runs fine. You can replace the bands and the clutch packs in the car without pulling the transmission. It takes 2 to 3 hours.

From John:

There is a definite reason for the famous "Clunk" when the rear wheel drive cars are put into Reverse. It is designed in. I'll try to condense this and if you can't follow it all, let me know. 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. Later, I remember a Dodge truck that had a terrible chatter in reverse gear while on an incline - I found out the the factory tried to modify the harsh engagement and it was a failure. Several Service Bulletins are stillavailable on this subject, but I don't think they ever really eliminated it.

From John:

Harsh engagement of reverse is a common complaint about these cars. Adjusting the bands will probably make it worse, because it will make the reverse band pull in even more quickly than it does now, assuming it was properly adjusted in the past and has merely worn some from use.

A more productive endeavor would be to investigate your driveline for any play, and verify that all your motor, transmission and differential mounts are robust and tight.

Lastly, you might consider parking the car such that it can be driven forward when first starting the engine, rather than having to reverse out of your parking place.

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