Notices
Motor Sports If you like rallying, road racing, autoxing, or track events, then this is the spot for you.

Driveshaft upgrades

Thread Tools
 
Search this Thread
 
Old Sep 26, 2019, 08:17 AM
  #16  
Evolved Member
Thread Starter
iTrader: (15)
 
Balrok's Avatar
 
Join Date: Jun 2006
Location: North GA
Posts: 4,167
Received 209 Likes on 189 Posts
How off are we talking? A couple mil or a couple inches?
Old Sep 26, 2019, 08:25 AM
  #17  
EvoM Community Team Leader
 
Biggiesacks's Avatar
 
Join Date: Aug 2005
Location: West Coast
Posts: 5,688
Received 704 Likes on 592 Posts
you guys keep talking about the CV joints, but what about the lobro joint that allows the shaft to lengthen / shorten with the engine torquing?

or are we just calling that a cv joint? Maybe I'm just confused about the purpose of that joint and its just a brand name for a type of CV?

Last edited by Biggiesacks; Sep 26, 2019 at 08:47 AM.
Old Sep 26, 2019, 08:45 AM
  #18  
EvoM Community Team Leader
 
Biggiesacks's Avatar
 
Join Date: Aug 2005
Location: West Coast
Posts: 5,688
Received 704 Likes on 592 Posts
dbl post...
Old Sep 26, 2019, 08:51 AM
  #19  
EvoM Guru
iTrader: (1)
 
LetsGetThisDone's Avatar
 
Join Date: Oct 2013
Location: Las Vegas
Posts: 15,756
Received 1,543 Likes on 1,322 Posts
Originally Posted by Biggiesacks
you guys keep talking about the CV joints, but what about the lobro joint that allows the shaft to lengthen / shorten with the engine torquing?

or are we just calling that a cv joint? Maybe I'm just confused about the purpose of that joint and its just a brand name for a type of CV?
The transfercase has a slip yoke, that accounts for the engine moving. If the rear diff is on poly bushings (which it should be) it doesn't move enough to worry about the rear part of the shaft being fixed length.
The following users liked this post:
Biggiesacks (Sep 26, 2019)
Old Sep 26, 2019, 08:53 AM
  #20  
EvoM Community Team Leader
 
Biggiesacks's Avatar
 
Join Date: Aug 2005
Location: West Coast
Posts: 5,688
Received 704 Likes on 592 Posts
Originally Posted by letsgetthisdone
The transfercase has a slip yoke, that accounts for the engine moving. If the rear diff is on poly bushings (which it should be) it doesn't move enough to worry about the rear part of the shaft being fixed length.
Thnx, that's what I was concerned about.
Old Sep 26, 2019, 10:07 AM
  #21  
EvoM Guru
iTrader: (2)
 
Ayoustin's Avatar
 
Join Date: Jul 2014
Location: Detroit
Posts: 2,895
Received 579 Likes on 434 Posts
I've never heard of carbon driveshafts being more smooth vs other materials and I've driven a couple cars that use them. It's normally just owners trying to bring justification to their $1500 investment through placebo. The construction of using a fibrous material might dampen vibrations but think about this logically, it will only help things downstream, so just the rear diff, and how many people have blown apart diffs? Hypoid gears are inherently strong and being bathed in a very thick gear oil means that small vibrations won't even be noticed by the gears.

The most important thing about a driveshaft with regards to making things smooth other than using proper joints is to make sure that the natural frequency of the shaft is in an unreachable area of operation, this is done via proper balancing.

Carbon is for people that want to boast about how much cool **** their car has. I've seen too many of them fail to recommend one to anyone serious about racing because at the end of the day the strength of the shaft isn't the strength of the carbon, it's the strength of the epoxy resin that's bonding the carbon to the aluminum yoke ends and I'm sure that resin isn't getting stronger being exposed to exhaust heat.
The following users liked this post:
alpinaturbo (Sep 26, 2019)
Old Sep 26, 2019, 11:05 AM
  #22  
EvoM Guru
iTrader: (1)
 
LetsGetThisDone's Avatar
 
Join Date: Oct 2013
Location: Las Vegas
Posts: 15,756
Received 1,543 Likes on 1,322 Posts
Originally Posted by ayoustin
I've never heard of carbon driveshafts being more smooth vs other materials and I've driven a couple cars that use them. It's normally just owners trying to bring justification to their $1500 investment through placebo. The construction of using a fibrous material might dampen vibrations but think about this logically, it will only help things downstream, so just the rear diff, and how many people have blown apart diffs? Hypoid gears are inherently strong and being bathed in a very thick gear oil means that small vibrations won't even be noticed by the gears.

The most important thing about a driveshaft with regards to making things smooth other than using proper joints is to make sure that the natural frequency of the shaft is in an unreachable area of operation, this is done via proper balancing.

Carbon is for people that want to boast about how much cool **** their car has. I've seen too many of them fail to recommend one to anyone serious about racing because at the end of the day the strength of the shaft isn't the strength of the carbon, it's the strength of the epoxy resin that's bonding the carbon to the aluminum yoke ends and I'm sure that resin isn't getting stronger being exposed to exhaust heat.
The CT9a diff breaks all the time. Hence the need for a billet side cover. Autocross guys also break rear axles. The fast drag cars go to a 3000gt rear diff, etc..

The torsional twist which absorbs drivetrain Shock is certainly not felt by the driver, but it does happen.
Old Sep 26, 2019, 11:52 AM
  #23  
EvoM Guru
iTrader: (1)
 
Dallas J's Avatar
 
Join Date: Jul 2004
Location: Portland, Or
Posts: 5,810
Received 735 Likes on 570 Posts
From what I've seen it's basically reducing the impact loads causing force spikes in times of like wheel hop or harsh gear changes. Impulse loading is still there just preventing the damage from spikes over small delta-T.
Old Sep 26, 2019, 11:56 AM
  #24  
Evolved Member
iTrader: (34)
 
deeman101's Avatar
 
Join Date: May 2010
Location: Bethesda, MD
Posts: 1,142
Received 46 Likes on 37 Posts
The smoothness in the ct9a comes from taking out the CV joints/carriers (not the slip yoke). The stock driveshaft is a 3 piece unit with 2 carriers. Taking out each carrier is a major difference in smoothness/directness in power transfer. I doubt anyone can detect the difference between 2 piece aluminum versus 2 piece carbon. 1 piece carbon though (another carrier removed) will make a noticeable difference over any 2 piece unit.
Old Sep 26, 2019, 12:57 PM
  #25  
Evolved Member
iTrader: (5)
 
alpinaturbo's Avatar
 
Join Date: Mar 2007
Location: California
Posts: 790
Received 52 Likes on 42 Posts
Deeman101,
Can you expand on the 1 piece driveshaft in Carbon...seems you tried it and have evidence it can work.
We would all like to know, even if hesitant and concerned.

Thank you.
Old Sep 26, 2019, 03:01 PM
  #26  
EvoM Guru
 
Bee-Raddd's Avatar
 
Join Date: Mar 2009
Location: auckland, new zealand
Posts: 1,383
Received 273 Likes on 203 Posts
Originally Posted by ayoustin
I've never heard of carbon driveshafts being more smooth vs other materials and I've driven a couple cars that use them. It's normally just owners trying to bring justification to their $1500 investment through placebo. The construction of using a fibrous material might dampen vibrations but think about this logically, it will only help things downstream, so just the rear diff, and how many people have blown apart diffs? Hypoid gears are inherently strong and being bathed in a very thick gear oil means that small vibrations won't even be noticed by the gears.

The most important thing about a driveshaft with regards to making things smooth other than using proper joints is to make sure that the natural frequency of the shaft is in an unreachable area of operation, this is done via proper balancing.

Carbon is for people that want to boast about how much cool **** their car has. I've seen too many of them fail to recommend one to anyone serious about racing because at the end of the day the strength of the shaft isn't the strength of the carbon, it's the strength of the epoxy resin that's bonding the carbon to the aluminum yoke ends and I'm sure that resin isn't getting stronger being exposed to exhaust heat.
I blew apart 2 AYC diffs in 1 season and when we removed the RS diff i borrowed id cracked the LSD housing in that one too hahahaha.
Old Sep 26, 2019, 03:02 PM
  #27  
EvoM Guru
 
Bee-Raddd's Avatar
 
Join Date: Mar 2009
Location: auckland, new zealand
Posts: 1,383
Received 273 Likes on 203 Posts
i noticed DSS offer 2 different driveshafts one for RS and one for AYC. is there a difference in length between the 2?
Old Sep 26, 2019, 03:27 PM
  #28  
EvoM Guru
iTrader: (2)
 
Ayoustin's Avatar
 
Join Date: Jul 2014
Location: Detroit
Posts: 2,895
Received 579 Likes on 434 Posts
Originally Posted by bee-raddd
I blew apart 2 AYC diffs in 1 season and when we removed the RS diff i borrowed id cracked the LSD housing in that one too hahahaha.
You're also on AYC diffs which last I checked are fair amount weaker. There are plenty of road race evos over 600whp here that don't have diff problems. So it's either your weak AYC diff or whoever is setting you diff up is doing it very wrong.


Originally Posted by letsgetthisdone
The CT9a diff breaks all the time. Hence the need for a billet side cover. Autocross guys also break rear axles. The fast drag cars go to a 3000gt rear diff, etc..

The torsional twist which absorbs drivetrain Shock is certainly not felt by the driver, but it does happen.
The billet side cover is for the diff housing, not the gears. Lots of guys run 1000+hp drag cars on evo diffs, the 3kgt stuff is old school stuff that people do to save money vs building a diff. Breaking axles has nothing to do with diffs vibrations, they have their own CV joints.
Old Sep 26, 2019, 03:50 PM
  #29  
EvoM Guru
iTrader: (1)
 
LetsGetThisDone's Avatar
 
Join Date: Oct 2013
Location: Las Vegas
Posts: 15,756
Received 1,543 Likes on 1,322 Posts
Originally Posted by ayoustin
You're also on AYC diffs which last I checked are fair amount weaker. There are plenty of road race evos over 600whp here that don't have diff problems. So it's either your weak AYC diff or whoever is setting you diff up is doing it very wrong.The billet side cover is for the diff housing, not the gears. Lots of guys run 1000+hp drag cars on evo diffs, the 3kgt stuff is old school stuff that people do to save money vs building a diff. Breaking axles has nothing to do with diffs vibrations, they have their own CV joints.
Yeah, English Racing runs the 3000gt diff (also built) to save money to run 7's.. In a car with a dry sump and carbon doors and a dog box... Yeah, to save money.
Old Sep 26, 2019, 05:40 PM
  #30  
Evolved Member
iTrader: (34)
 
deeman101's Avatar
 
Join Date: May 2010
Location: Bethesda, MD
Posts: 1,142
Received 46 Likes on 37 Posts
Originally Posted by alpinaturbo
Deeman101,
Can you expand on the 1 piece driveshaft in Carbon...seems you tried it and have evidence it can work.
We would all like to know, even if hesitant and concerned.

Thank you.
I don't have personal experience running the 1 piece driveshaft. The only one is the PST 1 piece and you need to cut into the body to make it fit. Even then the angles on the CV joint at the rear diff and front yolk are pretty high. But the people that posted their results (tscomp and evodan2004) both said a lot of slack was taken out of the drivetrain and the car transfers power more immediately. Even though the weight savings wasn't that dramatic. Both had 2 piece aluminum driveshaft. Funny enough I had th same feelings going from stock to 2 piece. So I can imagine taking another carrier out only makes things that much better.
The following users liked this post:
alpinaturbo (Sep 26, 2019)


Quick Reply: Driveshaft upgrades



All times are GMT -7. The time now is 11:02 PM.