Speeding up by spinning less weight
7/5/07, 08:47 PM
#1
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Thread Starter
Speeding up by spinning less weight
I've been looking for ways to speed up my car without messing with the engine. I was originally looking at lightweight driveshafts and then lightweight wheels. Of course with lighter weight comes less strength. So I have 2 questions.
One of the biggest discussions between me and my friends (mechanical engineers) is metal fatigue, especially with dealing with aluminum. Steel will weaken as it's cyclically loaded, but only to about 50% of it's original strength. So the stock driveshaft will be fine for the forseeable life of the car (let's say 200-250k mi or 10-15 years). But Aluminum will weaken until it looses all of it's strength. Now how long it lasts depends on a great many things, including quality, environment, and driving style (I hit the gas hard quite often). But how long do the aluminum driveshafts typically last?
So then I started considering lightweight wheels, because they should make a bigger difference than the driveshaft. But of course, lightweight wheels stand a much higher chance of cracking than stock. How durable are these? Assume something like a BBS 19lb wheel or a typical aftermarket wheel of 20-25lbs. The style I'm going for, btw, is the FR500 style rims, so if anyone has any specific perspective into them, it'd be of great help. Thanks
One of the biggest discussions between me and my friends (mechanical engineers) is metal fatigue, especially with dealing with aluminum. Steel will weaken as it's cyclically loaded, but only to about 50% of it's original strength. So the stock driveshaft will be fine for the forseeable life of the car (let's say 200-250k mi or 10-15 years). But Aluminum will weaken until it looses all of it's strength. Now how long it lasts depends on a great many things, including quality, environment, and driving style (I hit the gas hard quite often). But how long do the aluminum driveshafts typically last?
So then I started considering lightweight wheels, because they should make a bigger difference than the driveshaft. But of course, lightweight wheels stand a much higher chance of cracking than stock. How durable are these? Assume something like a BBS 19lb wheel or a typical aftermarket wheel of 20-25lbs. The style I'm going for, btw, is the FR500 style rims, so if anyone has any specific perspective into them, it'd be of great help. Thanks
7/5/07, 08:57 PM
#2
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Shaun,
For hard driving, it really depends on how hard. Do you mean constant 5K launches, or from a roll you drive very spirited? Taking the car to 5K and letting loose from a good roll and from a dead stop are two very different things. Regardless, we've had aluminum driveshafts in Foxbody's go for thousands of miles. I still have one in mine
Steel is the same way, it's just the weight and dampening characteristics that I don't like.
I'd only go Coast or Spyder on the driveshaft, or Powerhouse/Driveshaft shop if they were priced a little more reasonably. Any one of those will be a good, long-lasting product. GET A SAFETY LOOP!
As for the wheels, I wouldn't get too hung up on weight. Just go with a reasonably-light pair of wheels that look good in your opinion. The driveshaft will get rid of more than enough.
CR
Tillman Speed
610-497-3711
For hard driving, it really depends on how hard. Do you mean constant 5K launches, or from a roll you drive very spirited? Taking the car to 5K and letting loose from a good roll and from a dead stop are two very different things. Regardless, we've had aluminum driveshafts in Foxbody's go for thousands of miles. I still have one in mine
Steel is the same way, it's just the weight and dampening characteristics that I don't like.I'd only go Coast or Spyder on the driveshaft, or Powerhouse/Driveshaft shop if they were priced a little more reasonably. Any one of those will be a good, long-lasting product. GET A SAFETY LOOP!
As for the wheels, I wouldn't get too hung up on weight. Just go with a reasonably-light pair of wheels that look good in your opinion. The driveshaft will get rid of more than enough.
CR
Tillman Speed
610-497-3711
7/5/07, 09:40 PM
#3
I also have a Dodge Charger Daytona. I put some steel aftermarket 20" wheels on it that were very heavy. I didn't like the looks of them, so I sold them and put the forged wheels from an SRT8 on the car, which are a lot lighter. I could definitely tell a difference in leaving the line with the lighter wheels. It takes less power to get them rolling.
7/5/07, 09:50 PM
#4
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Shaun, my experience with aluminum driveshafts is that they can take a lot and last a long time. I put one on my '96 and drove it for about 8 years. My son-in-law still has the car now. No problems, and he's got a lot heavier foot than me. I've had a PowerHouse aluminum driveshaft in my '05 GT for over a year now and it spins up just fine. No vibrations, no nothing. The aluminum that all the manufacturers use is aircraft grade alloy. Not quite as strong as chrome-molybdenum steel, but pretty close, and much less dense of course. And yes, as CR says, get a safety loop. They're cheap.
Price is an issue, but what can you do. The FRPP driveshaft for my '96 cost me $185. But 'dem days is gone forever.
The lightweight wheels are also a good idea. But they're gonna cost too.
Price is an issue, but what can you do. The FRPP driveshaft for my '96 cost me $185. But 'dem days is gone forever.
The lightweight wheels are also a good idea. But they're gonna cost too.
7/5/07, 09:53 PM
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7/5/07, 09:54 PM
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Reducing weight in rotating mass will make more of a difference than it would if you removed that same amount of weight from some other place in the car.
In terms of the reliability and longevity of an aluminum driveshaft your engineer friends are certainly correct however how long this takes and under what conditions are subject for debate. I do know many trucks now have aluminum driveshafts. I have an '07 Ranger 4.0 truck that came from the factory with an aluminum driveshaft and that vehicle has a towing capacity of something like 4750 lbs. I would imagine that my truck towing 4750 lbs would place as much if not more strain on the driveshaft than a 3500 lb Mustang GT would under WOT.
I got the Coast aluminum driveshaft from Tillman for my GT. I also got a BMR saftey loop. All is working well. I've had he car up to 130 mph with this D/S and it's perfectly smooth and I can defintely feel the difference in the accleration. The only issue I had was with the BMR loop hitting the lower block on my MGW shifter. This was easily fixed with a spacer plate.
So there's my 2 cents.
In terms of the reliability and longevity of an aluminum driveshaft your engineer friends are certainly correct however how long this takes and under what conditions are subject for debate. I do know many trucks now have aluminum driveshafts. I have an '07 Ranger 4.0 truck that came from the factory with an aluminum driveshaft and that vehicle has a towing capacity of something like 4750 lbs. I would imagine that my truck towing 4750 lbs would place as much if not more strain on the driveshaft than a 3500 lb Mustang GT would under WOT.
I got the Coast aluminum driveshaft from Tillman for my GT. I also got a BMR saftey loop. All is working well. I've had he car up to 130 mph with this D/S and it's perfectly smooth and I can defintely feel the difference in the accleration. The only issue I had was with the BMR loop hitting the lower block on my MGW shifter. This was easily fixed with a spacer plate.
So there's my 2 cents.
7/5/07, 11:24 PM
#7
legacy Tms Member
if really worried about wheels, get a set of spun or coldforged, or combo...we make forged wheels at work, and they can be twisted like a pretzel without cracking...cast is a different story- bad news is although forged is far superior metal-wise, its way more costly, and options are far more limited...castings require very little machining as face features are just molded into the part...we ran some cast wheels years ago, only machined about a pound off of the casting to finish it...most of the forgings have 20~40 pounds removed- a lot of that in slow/expensive 5 axis milling for the face pocketing...I'd opt for forged hands down all else equal, but no such thing as forged DD bullitts...I bought old torque thrust 'd' wheels for my 69, even though I hate castings- just gotta weigh strength/appearance/cost issues. basically I think any sema approved wheel is ok, but still- in a wreck/out of control situation, I'd still much rather have the wheel bend than break off the car...only really get that with a forged/spun wheel
7/6/07, 07:15 AM
#9
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Unless you're doing drag launches on slicks from every stop you'll never break a driveshaft. The joints will fail first. If you buy forged wheels they'll hold up well. If you do happen to ding one they can be repaired effectively. Cast wheels should be replaced if bent. Now, if your ultimate goal in all of this is a little extra speed, there are other places you can spend the dough that will have more affect. These are expensive mods. As stated earlier, if you're looking to shave as much weight as possible, then you'll see the most gain from shedding rotating mass for sure.
7/6/07, 07:18 AM
#10
Legacy TMS Member
An aluminum metal matrix composite driveshaft is your best bet, or carbon fiber. Regular aluminum is OK (Ford uses it only because it is cheaper than AMMC / MMX).
7/6/07, 09:58 AM
#11
Don't forget lightweight flywheels and UDP's...Buying true lightweight wheels costs more then then the UDP's, flywheel, and DS. And most likely you will be switching tires too...
7/7/07, 02:46 PM
#12
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Thread Starter
Wow, I didn't expect this kind of response.
You could always give us a discount 
My typical driving style thanks to these **** Virgina/DC drivers (I have no patience anymore) is a 1200-1600rpm launch (sometimes I'll do 2000-2500 if I want to make a show on my autocross-stressed Pirellis), then 50-95% throttle in 1st to 30, a healthy firm shift into 2nd with a short jump to 3rd or 4th and then coast into 5th. I always engine brake (I do RPM match to my best ability). A driveshaft safety loop would be a must.
Interesting point...
Yeah unfortunately I don't seem to be coming across too many forged wheels. Or at least ones that explicetly say they're forged. But more on that later.
My tires are shot after a day of autocross, so luckily that's already on the menu. As far as the UDP's, i'd really prefer not to screw with the engine. I went with the CAI and tune because I can completely reverse back to 100% stock within 10 minutes and the dealer will never know. A UDP takes a little bit more time to put in. And while the flywheels themselves aren't that expensive, putting them in is. Plus if you go too light on the flywheel you get driveability issues.
Shaun,
For hard driving, it really depends on how hard. Do you mean constant 5K launches, or from a roll you drive very spirited? Taking the car to 5K and letting loose from a good roll and from a dead stop are two very different things. Regardless, we've had aluminum driveshafts in Foxbody's go for thousands of miles. I still have one in mine Steel is the same way, it's just the weight and dampening characteristics that I don't like.
I'd only go Coast or Spyder on the driveshaft, or Powerhouse/Driveshaft shop if they were priced a little more reasonably. Any one of those will be a good, long-lasting product. GET A SAFETY LOOP!
As for the wheels, I wouldn't get too hung up on weight. Just go with a reasonably-light pair of wheels that look good in your opinion. The driveshaft will get rid of more than enough.
CR
Tillman Speed
610-497-3711
For hard driving, it really depends on how hard. Do you mean constant 5K launches, or from a roll you drive very spirited? Taking the car to 5K and letting loose from a good roll and from a dead stop are two very different things. Regardless, we've had aluminum driveshafts in Foxbody's go for thousands of miles. I still have one in mine
Steel is the same way, it's just the weight and dampening characteristics that I don't like.I'd only go Coast or Spyder on the driveshaft, or Powerhouse/Driveshaft shop if they were priced a little more reasonably. Any one of those will be a good, long-lasting product. GET A SAFETY LOOP!
As for the wheels, I wouldn't get too hung up on weight. Just go with a reasonably-light pair of wheels that look good in your opinion. The driveshaft will get rid of more than enough.
CR
Tillman Speed
610-497-3711
...
In terms of the reliability and longevity of an aluminum driveshaft your engineer friends are certainly correct however how long this takes and under what conditions are subject for debate. I do know many trucks now have aluminum driveshafts. I have an '07 Ranger 4.0 truck that came from the factory with an aluminum driveshaft and that vehicle has a towing capacity of something like 4750 lbs. I would imagine that my truck towing 4750 lbs would place as much if not more strain on the driveshaft than a 3500 lb Mustang GT would under WOT.
In terms of the reliability and longevity of an aluminum driveshaft your engineer friends are certainly correct however how long this takes and under what conditions are subject for debate. I do know many trucks now have aluminum driveshafts. I have an '07 Ranger 4.0 truck that came from the factory with an aluminum driveshaft and that vehicle has a towing capacity of something like 4750 lbs. I would imagine that my truck towing 4750 lbs would place as much if not more strain on the driveshaft than a 3500 lb Mustang GT would under WOT.
if really worried about wheels, get a set of spun or coldforged, or combo...we make forged wheels at work, and they can be twisted like a pretzel without cracking...cast is a different story- bad news is although forged is far superior metal-wise, its way more costly, and options are far more limited...castings require very little machining as face features are just molded into the part...we ran some cast wheels years ago, only machined about a pound off of the casting to finish it...most of the forgings have 20~40 pounds removed- a lot of that in slow/expensive 5 axis milling for the face pocketing...I'd opt for forged hands down all else equal, but no such thing as forged DD bullitts...I bought old torque thrust 'd' wheels for my 69, even though I hate castings- just gotta weigh strength/appearance/cost issues. basically I think any sema approved wheel is ok, but still- in a wreck/out of control situation, I'd still much rather have the wheel bend than break off the car...only really get that with a forged/spun wheel
My tires are shot after a day of autocross, so luckily that's already on the menu. As far as the UDP's, i'd really prefer not to screw with the engine. I went with the CAI and tune because I can completely reverse back to 100% stock within 10 minutes and the dealer will never know. A UDP takes a little bit more time to put in. And while the flywheels themselves aren't that expensive, putting them in is. Plus if you go too light on the flywheel you get driveability issues.
7/7/07, 03:09 PM
#13
Legacy TMS Member
Thread Starter
Alright...and now more on the wheels. I've been looking high and low for information on FR500 style wheels, manufacturers, sites, weights, bolt patterns, prices, etc. Here's what I've figured out so far. The bolt pattern on the S197 is 5 x 4.50 or 5 x 114.3, with a typical offset of 38mm or so. As I've had trouble finding FR500 wheels with this offset, I started looking into the SN95 rims, which use the same bolt pattern but only a 25mm offset. I'm figuring if I get some spacers, I can clear the brakes whould I go with SN95 rims. Now to the results so far
##OEM 17x8 Bullitts###
http://www.newtakeoff.com/index.asp?...OD&ProdID=8160
17x8 Bullitt
says 23lbs ($99.99)
http://www.fordracingparts.com/parts...tKeyField=7868
17x8 Bullitt
25.00 lbs ($140)
http://www.tirerack.com/wheels/resul...All&sort=Brand
17x9 Shelby Torq-Thrust
22lbs ($203)
Any ideas to the weight discrepancy and which one is actually right (yeah the shelby's aren't the OEM rims, but I thought I'd add them for contrast since they're wider but somehow lighter than the stock ones of the same style)?
###FR500 Style ####
FR500 Style Rims
American Muscle GT4 Rims 18x9
http://www.americanmuscle.com/18x9-g...ated-2005.html
No Weight listed ($159.00)
CT-R Mustang GT-40 replica 18x9
http://www.ctrwheels.com/chrome.htm
26lbs ($265)
**OE Wheels Model Mustang 380 Anthracite Grey 18x9
http://www.mrbodykit.com/wheels/2005_2008.htm
26lbs ($138)
http://www.stage3motorsports.com/product/OE386SC-8912
no weight ($119)
Steeda Ford Racing FR500 Wheels 18x9
http://www.steeda.com/products/ford_racing_fr500.php
No weight listed ($235)
Wheel Replicas FR5 18x9 Anthracite
http://www.wheelreplicas.com/FR500.html
No weight listed ($519 all 4)
##Konig###
Stampede 18x9 No weight listed
http://www.konigwheels.com/catalog_p...ID=1&ss_id=494
Heatsink 18x9 no weight no price listed
http://www.konigwheels.com/catalog_p...ID=1&ss_id=479
Latemodel Restoration Supply FR500 Sandblast Charcoal 18x9
http://www.latemodelrestoration.com/...0%201&comp=LRS
No weight listed ($144.95)
###BBS RK 18x8.5####
SN95 Mustang only...need adapter
19lbs ($390 MSRP)
http://www.bbs-usa.com
###################
Now, the ones that have my attention are the BBS RK's (extremely expensive but lightest), the American Muscle GT-4s, the ones available through wheelreplicas.com, and especially the Konig Heatsink. The problem is that many of the ones that intrigue me the most don't have weights listed. Would anyone happen to have the weight specs on these?
And besides the BBS RK's, the ones that are listed weigh as much if not a little more than the rims I have. Wouldn't be much of a point in getting the rims for my intent if they weigh the same. Though these rims would look **** good. http://customerpics.americanmuscle.c...=28137&id=1928
And when I wanted to find out what the RK's looked like on my car, I put my xbox 360 to practial work for a change
http://picasaweb.google.com/Cavero42...05273343510434
http://picasaweb.google.com/Cavero42...05273343510450
##OEM 17x8 Bullitts###
http://www.newtakeoff.com/index.asp?...OD&ProdID=8160
17x8 Bullitt
says 23lbs ($99.99)
http://www.fordracingparts.com/parts...tKeyField=7868
17x8 Bullitt
25.00 lbs ($140)
http://www.tirerack.com/wheels/resul...All&sort=Brand
17x9 Shelby Torq-Thrust
22lbs ($203)
Any ideas to the weight discrepancy and which one is actually right (yeah the shelby's aren't the OEM rims, but I thought I'd add them for contrast since they're wider but somehow lighter than the stock ones of the same style)?
###FR500 Style ####
FR500 Style Rims
American Muscle GT4 Rims 18x9
http://www.americanmuscle.com/18x9-g...ated-2005.html
No Weight listed ($159.00)
CT-R Mustang GT-40 replica 18x9
http://www.ctrwheels.com/chrome.htm
26lbs ($265)
**OE Wheels Model Mustang 380 Anthracite Grey 18x9
http://www.mrbodykit.com/wheels/2005_2008.htm
26lbs ($138)
http://www.stage3motorsports.com/product/OE386SC-8912
no weight ($119)
Steeda Ford Racing FR500 Wheels 18x9
http://www.steeda.com/products/ford_racing_fr500.php
No weight listed ($235)
Wheel Replicas FR5 18x9 Anthracite
http://www.wheelreplicas.com/FR500.html
No weight listed ($519 all 4)
##Konig###
Stampede 18x9 No weight listed
http://www.konigwheels.com/catalog_p...ID=1&ss_id=494
Heatsink 18x9 no weight no price listed
http://www.konigwheels.com/catalog_p...ID=1&ss_id=479
Latemodel Restoration Supply FR500 Sandblast Charcoal 18x9
http://www.latemodelrestoration.com/...0%201&comp=LRS
No weight listed ($144.95)
###BBS RK 18x8.5####
SN95 Mustang only...need adapter
19lbs ($390 MSRP)
http://www.bbs-usa.com
###################
Now, the ones that have my attention are the BBS RK's (extremely expensive but lightest), the American Muscle GT-4s, the ones available through wheelreplicas.com, and especially the Konig Heatsink. The problem is that many of the ones that intrigue me the most don't have weights listed. Would anyone happen to have the weight specs on these?
And besides the BBS RK's, the ones that are listed weigh as much if not a little more than the rims I have. Wouldn't be much of a point in getting the rims for my intent if they weigh the same. Though these rims would look **** good. http://customerpics.americanmuscle.c...=28137&id=1928
And when I wanted to find out what the RK's looked like on my car, I put my xbox 360 to practial work for a change
http://picasaweb.google.com/Cavero42...05273343510434
http://picasaweb.google.com/Cavero42...05273343510450
7/7/07, 07:28 PM
#14
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Stay away from replica wheels. They're all cast and usually relatively poor quality. The actual FR500 wheels ARE forged and I believe are OEM'd by BBS, but they're crazy expensive. My forged BBS RGRs are about 18lbs. if I recall. But, as you mentioned, they too are pretty darn expensive. I have about $5k in wheels/tires.
7/8/07, 08:29 AM
#15
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'05-07 OEM Bullitts weighed 22lbs on my scale. Some say 21lbs. I went with FRPP 17" Polished Bullitts in order to keep weight down, and to be able to run my stock tire. Since my stock DS is causing vibs, a Spyder DS + loop is in my future.
7/8/07, 04:40 PM
#16
Legacy TMS Member
Thread Starter
WELL THANKS FOR ALL THE HELP GUYS BUT YOU CAN CANCEL THIS THREAD. I HAD THE CAR JACKED UP TODAY SO I COULD TAKE THE WHEELS OFF AND CLEAN THE RIMS THOROUGHLY. WELL FIRST I JACKED IT UP BY THE DIFF AND THEN TOOK THE REAR PASSENGER WHEEL OFF AND THEN STARTED JACKING IT SOME MORE SO I COULD PUT THE JACKSTANDS UNDER IT, AND THEN THE JACK SLIPPED OFF THE DIFF AND THE CAR CAME CRASHING DOWN. THERE WAS NO IMMEDIATE APPARENT DAMAGE, BUT WHEN I TOOK THE CAR FOR A TEST DRIVE TO MAKE SURE, IT WAS MAKING THIS HORRIBLE GROANING NOISE FROM THE REAR PASSENGER WHEEL. ****ING PERFECT. SO NOW ALL THE MONEY I HAD SAVED UP FOR LIGHTENING THE CAR IS GOING TO GO TOWARDS FIXING THIS. THIS IS ALL I NEEDED. THANKS ANYWAY. 
7/8/07, 06:11 PM
#17
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I believe it's poor practice to lift by the diff, and not recommended...
As for the driveshaft issue, AL d/s's are used by most oems, so I wouldn't worry about fundamental fatigue issues, however I question the QC of many aftermarket parts.
As for the driveshaft issue, AL d/s's are used by most oems, so I wouldn't worry about fundamental fatigue issues, however I question the QC of many aftermarket parts.
7/8/07, 07:34 PM
#18
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Very sorry to hear your car came off the jack and glad to hear your were not hurt. Here is a case for religiously using jack stands, even just to take off a wheel.
7/8/07, 07:38 PM
#19
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7/8/07, 07:39 PM
#20
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