transmission weights for GM

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phantomfab
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transmission weights for GM

Post by phantomfab » Mon Feb 13, 2017 4:08 am

Any body know the rotating weights for alot of GM transmissions? I'm not talking total weight but how much weight is being swung around in the transmission before it get to the driveline. I'm curious of the weights of a th350, th400, powerglide, saginaw 3 speed, and muncie 4 speed. All of which i want to know without th eweight of the clutch or torque converters being involved. Thanks guys for any input, I know this one is a little far out there but i'm really wanting to know. Gearing and amount of gears doesn't matter to me, these weights are wanted to know for reference in a circle track car that isn't shifting. Thanks.

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Re: transmission weights for GM

Post by PackardV8 » Mon Feb 13, 2017 12:59 pm

Does anyone else think transmission internal rotating weight may not be the determining factor in the equation? With the automatics, there's the pump and fluid drag also. Comparing a torque converter versus a roundtrack skeleton flywheel and clutch? Weight of the AT fluid and cooler?

Then, way back, didn't we have a discussion where sprints without the front balance damper weren't any faster, but the engines broke sooner?

Having said all this, I remember way back when in Alabama short-track, the late, great Roundman Amick ran a high-stall converter in front of an in-out box. His plan was to keep the engine up on the cam coming out of the corner. Won a lot of races with it.

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Re: transmission weights for GM

Post by pdq67 » Mon Feb 13, 2017 1:46 pm

If I recall right?

Onna the old mags printed this information, but finding it???

It was in something like, "percent powertrain loss", for the various automatics.

Don't have a clue about the sticks?

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Re: transmission weights for GM

Post by BOOT » Mon Feb 13, 2017 6:18 pm

I've kinda wondered this stuff myself, but not messing with trans much I've never even compared parts stock vs aftermarket. I would think it sorta changes per gear, like how weight after the diff gear change is even less beneficial depending on the ratio. So the output shaft wouldn't effect as much compared to the input, still both have a small diameter so the inertia would be much compared to the converter or other parts???
I know as much as I can learn and try to keep an open mind to anything!

If I didn't overthink stuff I wouldn't be on speedtalk!

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Re: transmission weights for GM

Post by Greenlight » Mon Feb 13, 2017 11:37 pm

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Re: transmission weights for GM

Post by ChevyEFI » Tue Feb 14, 2017 9:52 pm

If you think saving grams and ounces matters, run a TH200(-C) instead of a TH400.

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Re: transmission weights for GM

Post by pdq67 » Tue Feb 14, 2017 11:51 pm

ChevyEFI wrote:If you think saving grams and ounces matters, run a TH200(-C) instead of a TH400.
Or a 2-gear circle track stick tranny.

pdq67

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Re: transmission weights for GM

Post by phantomfab » Wed Feb 15, 2017 2:28 am

ChevyEFI wrote:If you think saving grams and ounces matters, run a TH200(-C) instead of a TH400.
I was just wondering how big the difference was. Cause I've always ran a 350 or 400 cause of how cheap they are around where im at. The glides are high dollar and was wondering how much of a weight difference there actually was. And while i was at it i was wondering the weights of the autos to the standards while i was on the topic.

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Re: transmission weights for GM

Post by phantomfab » Wed Feb 15, 2017 2:36 am

PackardV8 wrote:Does anyone else think transmission internal rotating weight may not be the determining factor in the equation? With the automatics, there's the pump and fluid drag also. Comparing a torque converter versus a roundtrack skeleton flywheel and clutch? Weight of the AT fluid and cooler?

Then, way back, didn't we have a discussion where sprints without the front balance damper weren't any faster, but the engines broke sooner?

Having said all this, I remember way back when in Alabama short-track, the late, great Roundman Amick ran a high-stall converter in front of an in-out box. His plan was to keep the engine up on the cam coming out of the corner. Won a lot of races with it.

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See i always thought this would work but after talking to some local guys that have tried stall converters have found that the stall converters blew the tires made the car hard to setup cause of the harshness of the converter engaging off the corners and that they were blowing through the converter most of the time later on down the straight away. But they were also trying to mess with running the stall with a higher gear and let the converter slip to pull it. They found that a tighter than stock converter with a lower gear worked a lot better. Still had the quickness off the corner and didnt blow through the converter on down the track. Now they did find out the problem of blowing through the converter went away with a lower gear but the converter was pointless then cause they were above the stall speed coming off the corner. So in the end, running a lower gear with a tighter converter was faster rpm to car speed then the car was with a high gear and a stall cause the converter was so loose it was just blowing threw it.

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Re: transmission weights for GM

Post by phantomfab » Wed Feb 15, 2017 2:39 am

pdq67 wrote:
ChevyEFI wrote:If you think saving grams and ounces matters, run a TH200(-C) instead of a TH400.
Or a 2-gear circle track stick tranny.

pdq67

clutch and flywheel weight is alot higher then a direct drive coupler and flexplate. but i was wondering if internal weight made up for the difference.

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Re: transmission weights for GM

Post by phantomfab » Wed Feb 15, 2017 2:49 am

pdq67 wrote:If I recall right?

Onna the old mags printed this information, but finding it???

It was in something like, "percent powertrain loss", for the various automatics.

Don't have a clue about the sticks?

pdq67
yeah on a chassis dyno i've seen the power go from a 19 percent loss to a 15 percent loss going from a 4l60e to a t56 but the dyno isnt really a good way to tell the differnce between transmissions, The reason being a dyno doesnt show how much the transmission slows it down, a glide car puts more power to the ground but picks up 2 tenths at the dragstrip with a 400 cause of the extra gear. I know apples to oranges in a drag car that shifts to a circle track car in the same gear all the time. Those magazines do power comparisons on a chassis dyno. But with a stock or lightweight clutch to a car with a converter. You'll blow through the converter. In the circle track car a direct drive is legal in the autos. They gain the advantage of the weight on a 6 pound flex plate to a 16 lbs flywheel. Those being the lightest legally. And a 21 lbs clutch to a 4 lbs coupler for the auto. That was one of the reasons i was asking for weights not including the drives, cause i already know the weights of what i can run.

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Re: transmission weights for GM

Post by barnym17 » Fri Oct 27, 2017 7:19 am

i saw a 2 second loss of lap time comparing th350 with converter vs glide with coupler.It is huge this was on 3/8 th high bank dirt track. Deceleration is as a big a factor or bigger than acceleration with rotating weight.

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Re: transmission weights for GM

Post by tenxal » Mon Oct 30, 2017 9:42 am

ChevyEFI wrote:
Tue Feb 14, 2017 9:52 pm
If you think saving grams and ounces matters, run a TH200(-C) instead of a TH400.
It does. And I do. :wink:

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Re: transmission weights for GM

Post by autogear » Wed Nov 01, 2017 4:23 pm

Trying to compare a manual is a mixed bag for a lot of folks; because some helix angles are more efficient than others, which are certainly more efficient than a spur gear. Oil quantity, oil viscosity; bellhousing alignment, fluid pump, tapered bearings or ball bearings; ratios make a difference too.
REM-type polishing is a big help, and if you're handy with a lathe, you can trim down a few things a little bit...but they have to be the RIGHT things.
What I CAN tell you is a 2 speed saginaw is hard to beat if you can find enough pieces in good repair and you don't shred the 10-spline input. But you're left with dwindling parts resources, cast iron case, etc etc.
An aftermarket Muncie with italian made gears, shafts and synchros; is more efficient than the ST10 variants and stronger to boot.
In SCCA A-sedan, we were lighter than the Super T10s we replaced, even the ones with magnesium tailhousings.

C&R racing was trying to sell an extremely lightweight 4speed to NASCAR, and it got banned almost immediately. I kinda wonder if theres any kicking around; but I really worry about durability and longevity

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