How off are we talking? A couple mil or a couple inches?

 

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?

 

dbl post...

 

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.

 

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.

 

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.

 

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.

 

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 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.

 

i noticed DSS offer 2 different driveshafts one for RS and one for AYC. is there a difference in length between the 2?

 

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.

 

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.