Ratio lever on 727

AllKiller · Post by **AllKiller** » Fri Nov 23, 07 6:10 pm

Someone explain to me about this.... 4.2, 5.0, etc ....dont even know what i have, and why

Kev · Post by **Kev** » Fri Nov 23, 07 6:26 pm

You are probably talking about the front servo kickdown lever, this is available in various ratios depending on how quick/hard you want the front band to release, tailoring the shift feel. It's inside the box, so don't go thinking you can change it on a Saturday morning!!

Blue · Post by **Blue** » Fri Nov 23, 07 6:46 pm

The servo apply lever comes in various ratios, it applies the front band. The higher the ratio the faster it applies and the slower it release's. The holding pressure on the band is increased also. Here's a selection of ratio's and where it fits in. It's one of several things that go towards eliminating 2-3 gear bind up that all stock Torqueflites suffer from. A 4.2 or 3.8 seems to work well with a Cheetah valve body in my experience

AllKiller · Post by **AllKiller** » Fri Nov 23, 07 9:08 pm

Sorcerer and apprentice quality

thanks for the lay out Blue, 1000 words in a picture there

So, what do you need more fast apply or quicker release ?
Im guessing its apply

I read trans brakes need a 5.0 ??

Dave-R · Post by **Dave-R** » Fri Nov 23, 07 10:09 pm

Fitted a 5.0 in mine.

Blue · Post by **Blue** » Sat Nov 24, 07 9:04 am

On the front servo Steve, you want it to apply fast for 2nd gear and release fast so you can get the 3rd gear clutches on. This is where timing is crucial, on the 2-3 shift you have to be in both gears at once or the revs would flare up as it changed gear. The time it is in both gears is referred to as bind up or overlap, and it is this time you are trying to keep to a bare minimum. With a combination of line pressure, spring pressure, lever ratio and sometimes a restrictor, the release of the second gear band is speeded up and the application of the 3rd gear clutches is slowed down to get as crisp a 2-3 change as you can. With my cheetah set up I'm using a 4.2 lever with an "early" servo and 2 springs, 12 springs in the drum and no restrictor. Set up like that, the shift feels far better than when I used a 5.0 lever and only 1 spring in the servo, you could feel the bind on the upshift previously. Sorry if that all sounds a bit long winded but you did ask....

Pete · Post by **Pete** » Sat Nov 24, 07 9:22 am

AllKiller · Post by **AllKiller** » Sat Nov 24, 07 4:59 pm

Blue, yeah understand that.....well you gotta have a look at my auto soon...so we can work out whats best.
Thanks for explaining....i really had know idea what it did

So it really is a fine balance with the lever then