7t2vette

Then we agree to disagree, because I don't buy it, no matter what you say. For every auto manufacturer in the world that makes IRS rear wheel driven cars to universally use CV joints in the half shafts, there has to be an advantage to them over u-joints. I do not believe that modern automotive technology goes backwards, it moves ahead, like everything else. Nothing you can say will make me think otherwise. Maybe you should email all the automotive companies that produce IRS rear wheel driven cars with CV joints to tell them that they are doing it all wrong then!!!

This is awesome! So, how exactly do you know this?!?! I can assure you most certainly that you are wrong, these are close personal friends of mine, the guys that I hang around with!!!! The only changes are installing DTE rear end girdles, and the C5 guys change the output shafts to C6 ZO6 units. Stock CV joints and half shafts.




I have been in the room for many dyno pulls, I know first hand how small the drivetrain losses are for modern Corvettes compared to C3's. Every part of the drivetrain in those cars is obviously more efficient than our cars, a stack of better tolerances adds up to smaller losses, and those CV joints are in that stack.

This is really going nowhere fast, isn't it?!?

wcsinx

You do realize there are many brand new vehicles currently being produced that use U-joints. right?

Do you understand how you just contradicted yourself? Jeezus h. buddy, you sound like a ricer. "Yo yo, my civic is totally stock except for dis turboz, yo"

You do know what "stock" means, right?

And exactly how does your being in the room for a dyno pull equate to this intrinsic knowledge you think you have of driveline losses? Are you telekinetic now too? And btw we're talking about CV v/s u-joints here, so stop trying to backpeddle with your "stack" Multiple people in this thread have now tried to explain to you that with a u-joint axle pointed straight, there is no more loss than a live axle or CV joint. The miniscule difference, if it was even measureable, would be due to the inertial moment of the shaft (as Skunkworks mentioned earlier) and not the design of the joint.

Mostly because you don't understand what you're talking about and are unwilling to learn.

wcsinx

Winner winner! chicken dinner!

That point has actually been raised. I don't think a traditional CV joint could be modified to handle the axial loading. I could be wrong, but having assembled many a CV joint it's clear to me that they're designed not to resist axial movement. And when you do load them axially, they fail real fast.

The solution is to modify the rear suspension such that you have an actual upper strut rod and the half shaft no longer performs a double duty.

Ravoll

Main reason being is the price,and the fact that most modern vehicles are front wheel drive.That means they have plenty of the cv axles laying around.Kinda like ,"Hey lets design a new car to fit these axles"


European rear wheel drive cars use central mounted diff with CV axles.Opel, BMW, Jaguar,Mercedes Benz....on and on and on.Axial movement is taken out by using a strut type suspension just like in the front drive junk.Or double wishbone as the case with the older jags.

Have been messing with cars my whole life and I have never seen anything like the C3 rear setup.Even the German engineers at my inspection station dropped there jaws when I explained to them why I didn't "need" an upper control arm.

7t2vette

Here are some pics I took at last year's ALMS race at Mid-Ohio of one of the factory C6.R Corvette's getting a rear end change in the paddock. Even these cars use the CV joints, but I guess they wouldn't be considered an "extreme" use example though!!

PeteZO6

The E-type Jaguar, which came out in 1961, used an IRS system quite similar to the C2/C3 setup. Chief difference was the use of two coil-over shocks per wheel instead of a transverse spring, and fore/aft location was mainly by use of stout H shape lower control arms. They had a trailing arm on each side that used rubber mounts so it as precise as our trailing arms for fore/aft location.

Ya used to see a lot of 'em (Jag rears) all chromed up under the back end of hot rods like T-buckets, high-boys and so on.

Pete

7t2vette

We are not talking about driveshafts where u-joints are still mostly used, but even those are moving away from using u-joints. As an example, C5 or C6 Corvettes do not have u-joints on the driveshaft.

Name one modern production vehicle that uses u-joints on the half shafts in an IRS rear wheel driven configuration, or even a 4 wheel drive vehicle with an IRS. I'll wait.


Yes, that is exactly what I sound like.

WTF are you talking about? How did I contradict myself? Who is the one that isn't paying attention here? The subject of this thread is CV joints, which I clearly stated are stock on the cars I mentioned that my friends own, along with the halfshafts. They did mods to other parts, but not the CV joints or halfshafts. The mods they did have nothing to do with the CV joints or half shafts.

Go on, scroll back to my previous post and re-read it again.

So, yes, I do know what stock means, in relation to CV joints and halfshafts.

No backpedalling here. The chassis dyno numbers show the losses between flywheel hp and rear wheel hp. It is easy to extrapolate the % of losses incurred when you already know the flywheel hp. It's not rocket science, but you seem confused by it. Are you now going to tell me that the u-joints or the CV joints are not part of the drivetrain, or that they contribute nothing to drivetrain losses? Ridiculous. Everything in the drivetrain incurs losses, and added up, create the total losses between the flywheel and rear wheels.

As for being telekinetic, I never said I could move things with my mind, so WTF are you talking about?




No one knows everything, and I am always willing to learn, but other than trying to shove your opinions down my throat, what exactly are you trying to teach me? What exactly is your point anyways? That u-joints are superior to CV joints?

My only point, which I have clearly stated several times already, is once again simply this, and this time I will type it slowly so you can understand it easier:

For the entire auto industry to universally, across the board, accept the use of CV jointed halfshafts in modern production IRS 2 or 4 wheel drive cars, the advantages of using them must outweigh any advantages that u-jointed halfshafts have. This is true for the cheapest to the most expensive cars produced. Progress means moving forward, not back.

I still think you should contact all the world's auto manufacturers and tell them they are doing it all wrong using CV jointed halfshafts!

wcsinx

They use flex couplers. Which have virtually nothing in common with CV-joints. Nice try at yet another red herring though!

Yeah, nice of you to narrow it down like that. I can name you many vehicles that still roll out of the factory with u-joints, but you specifically want IRS vehicles? Ok buddy. You might as well try to find a modern computer controlled mass production car with a carburetor. I've explained to you several times why CV joints are preferred in an IRS setup. But you simply can't comprehend this.

Here, I'll boldface the parts that make you a ricer.

I'll use small words for you. If the part wasn't designed to be on your car when it rolled out of the factory it isn't stock. Furthermore if your "close personal friends" are actually making passes with 1000+ HP on stock C6 Z06 shafts, then I'm calling b.s.

So you've managed to extrapolate that the difference in driveline losses between a C5 and a C3 is strictly due to the use of U-joints?

One of us is most certainly confused. But it ain't me.

Multiple people in this thread have now told you that in a straight drive situation as you'd find on a dyno, the loss through a u-joint will not be significant. But you didn't understand that then. And you won't understand it now.

Show me where I said that. No please F'KING SHOW ME. What I have said MULTIPLE TIMES NOW is that BOTH configurations have advantages and disadvantages. It is not a case of one being universally better.

Again, I'm not the confused one here.

Again, you want to narrow the scope like this. And again I will challenge you to show me where I contradicted this. However even in this scope, there are advantages to u-joint setup, and I've explained this to you before. Less weight, stronger, no rubber boot to get damaged ... but the drawback is once the joint is articulated, your axles no longer move at a constant angular velocity relative to the differential/driveshaft. As with many things it's a tradeoff. Most production cars have relatively large suspension throws so this effect can be very pronounced and with all eyes on fuel economy these days, that 1/10th of an MPG more can mean a lot. On the other hand a car with a very stiff suspension and short suspension throws may very well benefit from a u-joint setup, but when your tooling and available parts are all geared towards CV joints then...

then yes, it no longer makes sense from a cost perspective ... again more tradeoffs.

crystal clear yet?

GT's 78

If we were in a bar and alcohol was involved we would have to ask you guys to take it outside

wcsinx

I would've already hit him over the head with a stool.

LedfootLarry

remember the increase in weight of a larger dia. object increases in direct proportion to inertia , u-joint drive shafts are Larger diameter compared to a more compact and smoother running cv joint & shaft.
buddy, they want you back at the Billy-Joe-Jim-Bob hillbillybutf*ckr 4-wheel drive Alabama mud bog U-JOINT forums ,where you belong

wcsinx

Trying reading the entire thread. I'm well aware of the advantages of both, and I have explained them ad nauseum to your boyfriend up there.

LedfootLarry

Read the whole thing , But like I said Seabass at the Mudbogger forums want your expertise

69427

What?

I would say that inertia generally increases as weight increases, but I would not say that weight necessarily increases with inertia.

wcsinx

What he's trying to say in a most un-eloquent fashion is that the inertial moment of a shaft increases with it's radius.

Annnnnd this has been covered as well.

69427

I understand the physics quite well (freshman engineering). What I don't understand is his phrasing of the property.

wcsinx

Yeah, he really didn't phrase it correctly. I just knew what he meant.

Rather ironic that he accused me of being the idiot redneck in that same post wouldn't you say?

Raphiki

We should probably thank the OP for starting an interesting discussion. BTW - is there an ignore filter on this forum? I mean just in case someone turns into a total a-hole!

TheSkunkWorks

Raphiki, individual members can put others on their own private ignore list, and I've taken advantage of that feature on a number of occasions myself. With the attitude the OP had, I can't find it within myself to say thanks, but IMHO the topic of CV's is overdue being brought back up. Sadly, if you've been paying attention, you see where we are now.

Anyone who would like to abandon this epic fail and resume actual discussion on the possibilities of doing CV's without arguing over their merit, feel free to assemble here...

http://forums.corvetteforum.com/c3-t...post1579862153

pauldana

Heck!!! this is as good as when Mike and I go at it!!!!