Landracing Forum
Tech Information => Technical Discussion => Topic started by: Racerboy on October 04, 2008, 12:28:21 AM
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I am thinking of using a new Muncie 4 speed with a .86 overdrive (4th gear) in my new B comp coupe. I am thinking of turning the motor around 7500 + RPM. I have been told by some people that a 4 speed will not last and that they burn up because of poor oiling at those speeds. Please chime in with your help
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I have a super t10 for sale ,I know of one roadster that went 257 with one.
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What are the gear ratios in the trans and has and what if any special work has been done to it. What is your #
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I don't know of any Muncie with an OD 4th. Tex, Jerico, etc with spline shafts will let you let you select your own gears. My .96 OD Tex went 217 with 750 HP. Others with higher ODs have gone in the 240's with no oiling problems. You can dry sump them and spray the bearings.
I have a early Tex T-10 with a fixed cluster .94 OD (1.60 first) from an early Busch Series V6 car I'm going to sell after its been gone thru. 28 spline disc shaft and a turbo 400 yoke style. Probably after the new year.
Look to Jerico or Tex..................Good Luck............JD
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I don't really know much about transmissions, but the Kugel's firebird had a Jericho 4 speed with a 2.13 final gear and that car went 300MPH. So, I would think Jericho would be a good way to go.
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Not much experience with LSR here, but you need to base trans decisions on engine torque. What works for one 1000hp engine may not work for another. Depends on the torque. If you have a 18,000rpm engine a little trans will work. If you have a 3,000rpm engine it has to be a monster.
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Well, not really so much on the salt. Traction is so limited that the tires will break loose (sometimes) before the transmission will lunch itself. Torque ratings are still important -- but not necessarily as much as if you're drag racing on sticky pavement.
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Dunno. Regardless of the final gearing, the trans just knows how much force is being applied to it. It could get the same load at 25 mph as 300mph, just depends on the gearing.
This is something the diesels nuts have fought with for awhile. A Powerglide that survive 2500HP in a car won't survive 1000HP in a diesel at the same car weight. In my case, I move my RPM up specifically to make the trans survive. If I tuned for a 3200rpm HP peak, I can trash the trans. If I move it to 4400rpm it lives, even though I make more HP by tuning up there.
A Formula One trans is a small trans, but they spin the snot out of them. Look at 100HP bike trans verses a 100HP car trans. Even then, the bike trans will suffer 200HP better than the car trans will, even though it's smaller.
As far as transmissions go, gearing up with RPM is safer than gearing up at the axle or tire.
And yes, you shouldn't need as much trans as drag racing needs due to the high impact load seen on launching.
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Call Tex Racing Trans they would know what would hold up.
We used a Doug Nash 2 speed quick change with a gear vendor overdrive trans in the 222 Camaro [288mph +]
and the gears inside always looked brand new, but we did twist the input shaft after several runs and [years] and twisted the replacement in half. Thats when we went with an Owens [similar to Lenco] with a much larger input shaft.
Motor has probably always put out 1500 ft lbs. and recently over 1900.
Good luck JL222
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Call Tex Racing Trans they would know what would hold up.
We used a Doug Nash 2 speed quick change with a gear vendor overdrive trans in the 222 Camaro [288mph +]
and the gears inside always looked brand new, but we did twist the input shaft after several runs and [years] and twisted the replacement in half. Thats when we went with an Owens [similar to Lenco] with a much larger input shaft.
Motor has probably always put out 1500 ft lbs. and recently over 1900.
Good luck JL222
Do you have contact info for Owens? Sounds like something that I need to look at.
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Call Tex Racing Trans they would know what would hold up.
We used a Doug Nash 2 speed quick change with a gear vendor overdrive trans in the 222 Camaro [288mph +]
and the gears inside always looked brand new, but we did twist the input shaft after several runs and [years] and twisted the replacement in half. Thats when we went with an Owens [similar to Lenco] with a much larger input shaft.
Motor has probably always put out 1500 ft lbs. and recently over 1900.
Good luck JL222
[/quote
Scot Owens Trans 559 539-2925 also in rule book pg 232
]
Do you have contact info for Owens? Sounds like something that I need to look at.
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Re: "In my case, I move my RPM up specifically to make the trans survive. If I tuned for a 3200rpm HP peak, I can trash the trans. If I move it to 4400rpm it lives, even though I make more HP by tuning up there."
Thanks, that's something I was aware of - but didn't know it applied to LSR.
The problem seems to be that (absent really high flywheel inertia) the input shaft and all whirly bits never "see" continuous flow of power, especially with low inertia parts - they get a series of really big hammer blows to the engagement surfaces (splines, flutes, dogs, blah). At lower speed, and with smaller number of cylinders the compression cycling hits it in the opposite direction.
This is true even with torque converters (although I suspect the pulse amplitude decays to near zero with stall speed) - the crank flange "ratcheting" behavior is still presen at the input shaft despite no mechanical connection.
If you can't reduce the amplitude (shock value) the next best thing is increase the frequency, and frequently moving the max power upscale does both (-10% torque but +20% RPM = more power and better gear life).
It also appears that a higher engagement number helps to some degree. Assuming equal execution, A/T drums with 54 splines take more abuse than 36 spline, dual or triple row small pitch chains last longer than equal nominal tensile load large pitch.
If the vehicle is traction limited, the maximum load the transmission sees won't be as high as if the tires didn't slip, but:
1. the engine still puts out all the transient power used to accel the bits right down to the tire
2. breaking traction > backing off > opening throttle cautiously > breaking traction > lather, rinse, repeat introduces load reversals to all the engagement points - always a bad thing.
3. IMHO the Tor-Sen stuff proves that helical gears don't like being loaded backwards, which is what happens to all diffs (Ford 9" especially bad) when the car is "dragged down" by the tires after breaking traction.
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Separate thought, separate post.
For really fast cars that will be traction limited: how many have used (or plan to) a Powerglide built for oval track?
Good features:
1. really low weight, short OA length
2. fewer moving parts
3. no converter = minimal heat and power loss, much reduced fluid cooling needs, high line pressure safer to use to keep friction surfaces engaged
4. start by lever or pedal engagement of fluid pressure to a band (?) to "slip" it so it can move away from stopped - harmless if used briefly
5. really bullet-proof parts commercially available - very little fab needed
6. simple shift linkage or none (I think reliable governors are available)
Bad:
1. only 2 gears (not that bad if you have enough power)
2. limited 1st gear ratios available:
1.76 (OEM)
1.82 (OEM)
1.90
1.94
2.08
2.18
no overdrive TIKO
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I chose a Shorty Glide with a GV for many of the reasons you mention---It is no longer than AT 400
1.76
1.37 OD
1.00
.78 OD
Tell GV you are running LSR, and they will change some of the valving and it can freewheel if you order it that way---not cheap though could have gone Liberty for about the same price. But Shorty glide one year---gv another..
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Is this a converter or direct drive?
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Direct---no control other than gearshift..
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I use a glide. It is 17in. long and is a direct drive with no fluid dump. Push it off in neutral and when you get to about 40 put it in low. I am probable giving up a few mph by not having 1 or 2 moe gears, but when you get in the 5th mile if you have any power your still going to go fast. I have a old Hot Rod book somewhere (50's) that has a front wheel drive roadster built by the guy that started CAE. It has one of his first in and out boxes he ever built and direct drive with a clutch (no trans !) and he ran 215mph first time out. His power was an old 354 hemi with injection!
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Betcha the gas "smelled funny".
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If the low number of ratios, wide RPM drop and low torque multiplication are acceptable compromises, the PG offers a big advantage: wouldn't it be nice to delete the entire "clutch question" (weight, spares, throwout bearing, inertia, linkage, leverage ratio, room in the cockpit for the control, less things for the driver to think about)?
I never thought I would say this back when I was young, stupid and completely broke (now I'm old, senile and almost poor) but any problem I can solve by buying something commercial (viz., known quality product, spares available by FedEx, does what I want) rather than make another fabrication project out of it... I'll just pay for it.
There's always something else I can't buy that needs my time and energy.
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For really fast cars that will be traction limited: how many have used (or plan to) a Powerglide built for oval track?
I recall seeing John Greenwood's IMSA 'Vette compete at Brainard International in the early '80's. He was running a modified powerglide at the time, and in a downpour that proved to be extremely traction limiting, (standing water in spots) he was able to smoothly apply power and moved up numerous positions on the rest of the field. On parts of the track where other cars would bust loose, JG just rolled right along.
Applicable to salt? :roll:
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I suspect he was using converter slippage as a buffer/traction aid, and it's possible to adjust stall underway using an adapted Super Turbine dual-pitch converter - IIRC it's what Jim Hall used in the 2J Hoovermatic car.
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I found a G Force 4 speed (Tex Racing) that I think will be a better fit and I can still get it with a 4 gear overdrive (.91). Can Anyone suggest some gear ratios The car is a C fuel Comp coupe and I will be running both B ville & El mirage
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I am thinking of using a new Muncie 4 speed with a .86 overdrive (4th gear) in my new B comp coupe.
Did you change your mind on the motor size and when are we going to see a picture of your comp coupe? :-D
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I will be running a C motor to start with then my B motor and a D motor along with anything else I can find around the shop
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I found a G Force 4 speed (Tex Racing) that I think will be a better fit and I can still get it with a 4 gear overdrive (.91). Can Anyone suggest some gear ratios The car is a C fuel Comp coupe and I will be running both B ville & El mirage
We have a G Force and love it and actually I think that G Force actually makes a lot of the Tex Racing transmission not the other way around, but I could be wrong.
We run the highest 1st that they could put in it (1.923) and I wish we could go higher than that. If you have any power at all and a good push vehicle you can use a high first to drop the rpm drop going into 2nd. We can still only use about 30%-50% in first and that is with the car weighing 5000 lbs and we are probably making 850-900 HP at the crank.
2nd is 1.331 and we still can't run WOT in 2nd either.
3rd is the 1.00 and is actually the normal 4th gear.
4th is .931 and is the normal 3rd run as an overdrive 4th like what you have.
You don't mention what your rear gears are, tire size and power/torque range. Maybe run it like it is the first year and data log rpm and tps and what ever else you can and then look at where you want to go from there with gears.
c ya,
Sum
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Sumner you are a genious.