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  #1  
Old 02-18-2003, 03:06 PM
FASTDARTCHESTER FASTDARTCHESTER is offline
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Default lightening the internals of a 904

I am in the process of building a 904 and have successfully trimmed close to 3 lbs total off of the rotating mass of various internals.

my question is this: has anyone lightened the sun gear shell by drilling holes in it? i did it on a spare shell i had laying around by drilling 1" dia hole at 45 deg intervals and it lightened the shell by almost 3/4 lb.

i have not run this yet but i was curious if anyone has tried it.

and no, i do not have the cabbage to buy aluminum drums.

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  #2  
Old 02-18-2003, 05:59 PM
CudaMike CudaMike is offline
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A&A Transmissions lightens the sun shells with some fairly large holes. I saw a picture or two in their catalog.
http://www.aandatrans.com/
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Old 02-18-2003, 06:06 PM
FASTDARTCHESTER FASTDARTCHESTER is offline
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Thanks man!

They don't show a picture though, probably so cheaters like me won't copy it!

I'm gonna try it anyway. It doesn't seem to sacrafice integrity at all.

Thanks again,

Tom
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Old 02-18-2003, 08:52 PM
CudaMike CudaMike is offline
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Cool

Fast, if you're not in a hurry why don't you call and get their catalog?
Anyway, I have the catalog in front of me. They show the shell from the side. There appear to be 8 holes around the O.D., and they are in line with the tangs that engage the front drum. Doing some scaling and proportioning, they appear to be 1 5/8" in diameter. You might would want to go 1 1/2" to be safe. The center of the holes are about 1 7/8" to 2" from the front edge of the tangs. I can't tell if there are any holes in the rear face of the shell. The 727 shells do have them, and they are spaced in between the ones on the O.D., if you know what I mean.
I'm an engineering tech and used to be a machinest, so I have some idea of what I am doing. Just take a hole template and a sharpie and lay it out and see if it looks good; measure twice, and cut once! Good luck.
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Old 02-18-2003, 10:02 PM
skankweirdall skankweirdall is offline
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A friend of mine did it and it worked fine until he got greedy and made one with bigger holes, crumpled like aluminum foil. Hope you have a trans shield just in case. Any way it was a Duster Stocker with a 360, didn't help it's ET's anyway. Just something to think about.

I understand the need to tinker and try things, but my personal opinion on this is the performance improvement will be nil. There might be a .015 gain if you went from a 727 to a 904, but by the time you get there I think any further improvement will be unmeasurable by real world standards. In other words the difference in atmospheric conditions alone is enough of a variable to make detecting any improvemnt nearly impossible, not to mention all the other variables involved in drag racing.

Don't mean to spoil your fun because that's what it's all about. So enjoy and I hope you prove me wrong.
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Old 02-19-2003, 10:00 AM
FASTDARTCHESTER FASTDARTCHESTER is offline
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word on the street is swapping from a 727 to a 904 is worth a tenth.

Also, I'm not just lightening the shell but the front and low gear drums, and i am using planetary gears with the aluminum housing out of a '69 904 (of course I used the planetarys and sun from the same trans so as not to mix gears). By the time I am done there will be close to 5 lbs shaved and that is off of the O.D.'s of some of the parts. It should be significant enough to see a gain because it is freeing up torque (you know, torque=forceXdistance). So in the end I am going for the cumulative effect of the weight savings on all the parts.

I guess I will see at the track this spring. It may help, it may not. I just broke the engine in during the fall so there was no time for me to hit the track last season, which also left me nothing to baseline against.

I'll keep you guys posted.

Who knows, I may even give cuda's 318 a run!
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Old 02-19-2003, 12:46 PM
skankweirdall skankweirdall is offline
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Quote:
Originally posted by FASTDARTCHESTER
word on the street is swapping from a 727 to a 904 is worth a tenth.
Maybe, it depends on the engine/car combo I think. A really small low torque engine might be that much. I've not done testing with mine but I know guys that have A/B'd Hemi's and big blocks with the Pro Trans 904 guts conversion and the gain was small, very small. In stock and super stock racing this is important. In bracket racing it's not. The loss of durability is also a factor here. I run a 904 in my car with good results. It has no lightening or special aluminum parts in it though. The one thing that made the biggest difference was the 2.74 low gear set. Good luck to you, hope it works out.
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Old 02-19-2003, 01:42 PM
FASTDARTCHESTER FASTDARTCHESTER is offline
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I agree with you on the low gears. I swapped a set in the 904 in my b-body and it made a huge difference. I use a 3.55:1 final and with the low gears the car thinks the final drive is in the 3.9's:1. It is a heavy car though, which accounts for the noticable gain.

I need the luck. I will let you know how the car runs in a few months.

By the way, does your 360 run 10's naturally aspirated?
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  #9  
Old 02-19-2003, 05:35 PM
skankweirdall skankweirdall is offline
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Yes, no hood scoop, all the steel and glass, except the hood and bumpers.

http://www.fenderforum.com/userphoto...html?recid=632

http://www.fenderforum.com/userphoto...html?recid=993
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