9C1 Plaque

[4.3CPI]

Hey guys, love the site.

On a buddy's 9C1 police package caprice, there is a plaque on the dash that says to use drive instead of overdrive, unless pursuing someone. Same basic trans, could this be beneficial to all 4L60-E owners in terms of longetivity?

 

[George Blake]

Re: 9C1 Plaque

That is an issue with the longevity of the 3-4 clutch pack. You will NEVER drive your car as much as a police cruiser gets driven. NEVER. The issue is under in town cruising conditions, you will only be in 4th for a short period of time. So your cycling the 3-4 clutch pack back and forth for 3rd and your applying and re applying the band and you are beating the hell out of the gear train as you grab the sun gear then let go of the sun gear then grab the sun gear. See what I mean? If you keep it in third, it doesn't beat the gear train and 3-4 clutches near as much. My recommendation if he just bought a police cruiser is to have the trans rebuilt as soon as possible.

 

[4.3CPI]

Re: 9C1 Plaque

So it IS beneficial to drive around in Drive! GM at least recognized the fact that these weren't the best trans's. Too bad the public didn't get the same badging. Thanks George.

 

[odium]

Re: 9C1 Plaque

Unless I am on the freeway, I am always in Drive.

If I know I am going to cycle between 40 - 50 a lot, I put it in drive too (traffic).

 

[jwaller]

Re: 9C1 Plaque

it's a know fact drive is better than OD unless you need the extra ratio. leaving it in D also locks in the overrun clutches helping to stabilze the sprag. GM also advised ppl to use D instead of OD when towing heavy loads.

 

[Foot Performance]

Re: 9C1 Plaque

plus if you in the drive the overun clutches apply to help the forward clutches hold

is that right george?

 

[George Blake]

Re: 9C1 Plaque

That's correct. You get two more clutches. It's just not good for the overrun clutches to apply suddenly when doing a manual 4-3 downshift.

 

[Foot Performance]

Re: 9C1 Plaque

that is what thought