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Discussion in 'Manton Push Rods Top Alcohol Tech Questions' started by TOL, Mar 6, 2018.
They are now running four and five speed Liberty transmission with a converter with great success
..........running them now almost like a clutch car $$$$$$$$$$
Ok I'm in. Not trying to steal the thread, just hopefully add to it. I'm starting the build of my first "pro mod" type car...
Anybody have any actual experience w 4-5 speed liberty? Or even 4-5 speed b&j/lenco in a screw blown door car?
How much harder/easier is it to set up a car like this with more gears? Would you start with the same ratio first gear as you would a 3 speed and split it up til 1:1? Would rear end ratios then be any different?
My builder says the same as above, hemi likes load, no need for more gears. Not trying to go against my builders experience, just curious for more information on the latest trends or past personal attempts at this.
We are building a b screw hemi in a steel door car with a quick lock converter drive for 1/4 mile. I'm not necessarily looking for a performance advantage, just want to pull as many gears as I can without it being a pain in the ass to get a good reliable set up. If 3 is faster, that's cool. But hearing 4 or 5 gear shifts is cooler in my book.
Thanks to all for your experience and posts, very much appreciated!
There has been talk on here about ring gear life with the lockup. I would guess it would be worse with the Liberty due to its a hard positive engagement and doesn’t have the clutch pack to soften the load of the shift like the Lenco. I prefer the Liberty in general, it’s light weight, strong, less rotating weight and no setup time like the Lenco (clutch packs and sprags). It’s like a set it and forget it type deal.
The pro stock guys tell me that they went with more low gear ratio when they switched to the Liberty because of their less rotational mass or flywheel effect than the Lenco stuff.
I don’t understand ???....
Wouldn’t it be nice to have a rugged CVT. Oooops, that’s a bad example of an oxymoron .....
Nitrous yes. Any with a blower yet?.....
Thanks for the insight. I wouldn't have considered the extra rotational force affecting the rear gear ratio, but that makes sense.
I addressed the ring gear issue with Steve at Quick Drive and he said this isn't a concern if set up properly. They are doing some cool things with fluid manipulation. Which is why I'm thinking that with the advancement in lock up torque converters and lock up converter drives, you would be able to take advantage of more gears. But maybe my thinking is incorrect. I didn't get a chance to touch on this with Steve, as my main concern was for the lock up damaging the ring gear, but I will this week. Plus the fact that I'm only trying to hook up about 2300 HP not 3500 should be easier on parts.
I tend to think the lessened ring gear life was more to do with the unlock/lock/unlock/lock/unlock/lock sequence shock loading being imparted at the converter.
A totally open converter (not lockup) while shifting a Liberty would probably be okay?? A totally locked converter while shifting a Liberty would probably be very hard on the internals of a Liberty with blower type torque?? Unlocking and locking a converter while shifting a Liberty, well that’s a whole lot of shock hammer loads going on and it would be anyone’s guess what would fail first??
Don’t really know for sure, just thinking out loud.......
There are plenty big name blown cars with 5 plus gears. Some run the liberty some run the Lenco. As mentioned above liberty is now making 6 and 7 speeds now. No ones going to come out and say that they have one. If you operate in a super tight power band, I’m sure it will work for you.
It was said that they are running it like a clutch car because they are, they are slipping the converter early and as the input shaft starts to catch the engine they lock it up solid for the rest of the run or they can unlock and lock as many times as they like. Kind of like a clutch. You can be light on the weight and slip it on the shift or you can hang some weight on it and lock it solid on the shift. Jim’s just old school and guys are spending 20,000 plus for a Liberty, converter drive, converter, mods to get that massive thing into the car etc. A clutch can accomplish the same same thing for a lot less money but more maintenance work, which no one seems to want to do anymore. I think with converter technology the way that it is, a non lockup converter could run just as good unless it is a nitrous car, they need all the help they can get.
Something else to think about, and I wonder about this from time to time and I encourage anyone to chime in if they have any insight; If you have an engine that has to accelerate 5 times in an 1/8th mile vs 3 times, the engine that is accelerating more times will be more sensitive to rotating weight, including converter and transmission parts. As well I would think that the rods would take it harder as well. I don’t have any proof of that as the engine accleration rate is something that you cannot readily “see” or quantify, but it’s there and it makes a difference, just ask a sprint car guy. Anyways, that’s my take on it.
More gears will be better until the point of diminishing returns, meaning complexity, mass, expense . . . pick one.
Go back to the CVT quote, very true, just painful to think of that way(Honda garbage), but similar to what any 2-stroke sled racer has always lived by, keep it in the powerband as long and as often as possible.
Let the convertor do the work.
"hemi's like to be loaded" is the same as "our convertor is off by a mile or junk".
With all of the convertor tech from the last 15 years .With a dozen or more this one is better than this .Its coming full circle slipping a little in low gear and going full locked up and using trans gear ratio like a clutch car would........ buy the trans, convertor ,spares,mods to the car 50 to 60 k Add that to the pile of old next best gadgets and gizmos and a clutch does not look that bad lol And with the ride the dot timing controls to don't have to kill the clutch to get the car down the track.like the old days.Just cool between rounds with a simple fan no stinky fluid or special coolers needed .With bronze floaters you don't have to re zero ever and can go at least 8 runs before a full service. and with pre ground clutch packs that can be done in a hour taking your time with one guy
Look at the aussie guys they all run clutches with rules of course, I think with all the new tech stuff you could run as fast with a clutch vs an auto. Sometimes it s a monkey see monkey do anymore.
It is real hard to get consistency out of a clutch. Just as soon as you think you got it you buy more discs that you thought was the same as you were using and all is lost. Most guys have a hard time with a clutch and are faster with a converter. This is not including less maintenance time between rounds
Great posts and great insight guys! Thanks!
I have zero experience in this type of build so any and all viewpoints to this subject are greatly appreciated.
I had originally started this build with the idea of a clutch car, but have since been dissuaded to go that route. Both from my builder (who runs a clutch) and from reading past threads on similar subjects. The idea of manually shifting a 100% all steel car with a 4 speed to 200+ mph in the 1/4 on a regular basis is my goal. 200 is a big deal at our humble facility. What this actually entails in the real world is where my lack of experience comes in. Which is why I chimed in to find a little more knowledge. Instead of learning clutch set ups I'm learning about converter drives etc...and now wondering how close I can get to my dreams of manually shifting through 4 or more gears with an converter drive.... I understand this has been accomplishment with a clutch for years.... But maintenance, mismatched discs etc etc....like I said, I've been dissuaded.
Again, the original post being "4 speed in a blown application"....my build is b screw hemi. I wasn't trying to turn this into another clutch vs converter thread, but maybe you can't talk on the subject of 4-5-6 speed transmissions in blown alcohol without touching on it. Especially if max performance at the highest level is main goal. Big $$$$ goes along way to that. Surplus of parts and time to test extensively. Obviously not me.
Thanks again for sharing your experiences, both for myself and to the original poster.