broken spicer u-joint...NA L6

[zredbaron]

okay, so I was under the impression that an NA L6 would be okay with spicer u joints, evidently i was wrong. i was trying to entice a ferrari to show me up...we were cruising at 80mph. i downshifted into 4th to make the tires chirp, lunge forward and show him i might me worthy. i slow back, look at him, he nods, i chirp again, but this time a loud pop and lots of banging. oh yeah and a tow truck. and now my wheel well is beat to $#!+.

 

so... i must ask. is this odd, breaking a spicer-u joint in this fashion? it seems odd to me. (i always thought if it would happen, it would be between 1st and 2nd!) is this a fluke or do i need to do the CV conversion? i have the r180 4.375 diff with a quaife atb inside. are there any other benefits to doing the CV conversion?

 

thanks,

mark

[Guest JAMIE T]

It was more than likely the downshift(which could have theoretically caused the rest of the drivetrain to slow down TOO much which would cause what you described as "chirp you tires"). That is a serious shock to the shafts, especially at 80 mph. Then, you suddenly got back on the throttle, reversing the situation. And, you did all this TWICE.

 

If you want to do that, or feel like your car should be capable of handling that, then stepping up to the CV's may be your answer. But, from my experiance, the U-joints are just as strong as the CV's until the rear is squating hard getting the U-joint out of alignment.

[zredbaron]

hmmm...if i understand you correctly, you are under the impression i used the downshift to slow the car. i was cruising with slight pedal in 5th at 80, then simultaneously downshifted and floored the gas as i let off the clutch to engage 4th. i doubt there was any decelleraction of the drivetrain, just accel.

 

or am i wrong?

 

i dont undertand what you mean by "the U-joints are just as strong as the CV's until the rear is squating hard getting the U-joint out of alignment."

 

thanks.

[Guest PROJECTRB240SX]

He's Saying When The U-joints Are No Longer In There Natural Positions And Actually Inline With The Diff Is When U-joints Start To Break..... When Your Rear-end Digs Towards The Pavment From Hard Launches, Etc. Is Normally When This Happens.

 

Actually I Think What Broke It Was The Shock Of Instant Acceleration.... You Actually Sped Up The Drivetrain By Downshifting.... Which Also Causes Alot Of Shock. We All Know Power Finds The Weakest Link And Demolishes It.

[RB26powered74zcar]

hmmm...if i understand you correctly' date=' you are under the impression i used the downshift to slow the car. i was cruising with slight pedal in 5th at 80, then simultaneously downshifted and floored the gas as i let off the clutch to engage 4th. i doubt there was any decelleraction of the drivetrain, just accel.

 

or am i wrong?

 

i dont undertand what you mean by "the U-joints are just as strong as the CV's until the rear is squating hard getting the U-joint out of alignment."

 

thanks.[/quote']

 

 

hmmm... did I read you right that your saying you did a downshift at 80mph into fourth gear, then cherp the tires...?

 

Thats one bada$$ NA L6 !!!

[johnc]

so... i must ask. is this odd, breaking a spicer-u joint in this fashion?

 

No, its sounds like you were doing all that you could to break something in the driveline. Congratulations, you succeeded.

[JMortensen]

Sometimes the truth hurts...

[zredbaron]

Thats one bada$$ NA L6 !!!

Thanks! Although there are a few out there that are even more baddass....

 

No, its sounds like you were doing all that you could to break something in the driveline. Congratulations, you succeeded.

Speak of the devil! Haha, thanks John (and Jon M). I missed you guys, too.

 

 

So, I see now that 'I was asking for it', but I am not 100% on the details. I know that causes a lot of stress on the drivetrain, but why did it break in that scenario, and not during full accelleration from 1st to 2nd (the tires slip for more than a chirp, and lunge the butt-dyno quite a bit more)? Wouldn't this stress with the wheels at a lower groundspeed be more devastating for the drivetrain? Or did I just find the straw that broke the camel's back?

 

As for CV joints...I am interested in the swap. I went to the MML website and all Ross' adapters are for R200s. Am I screwed with my R180? I've invested so much $$$ in it that I'm not willing to go to R200.

 

If I do manage to do the CV conversion, will putting this kind of stress on the drivetrain be...'more acceptable'? Let's be honest...it's a lot of fun and I'd like

to be able to do it without hurting anything but my tire tread. I've seen pics of CV halfshafts, they look like are wouldn't be any play in them...is this true?

 

Please comment on my conceptual errors!

 

Thanks, guys.

[JMortensen]

IMO when you do this stuff at higher speeds it is worse for the drivetrain because at lower speeds you can get more wheelspin or more acceleration. When I test a clutch for slippage I drive maybe 40 mph, put the car in 4th rev it up and drop the clutch. If the clutch slips and the engine doesn't immediately match the road speed, then you've got troubles. Note that this test doesn't work in 2nd gear, because you'll just spin the tires or the car just accelerates very quickly. In a higher gear the drivetrain doesn't have that as much leverage over the weight of the vehicle. So when you do what you did the tires can't break loose and the car can't instantly accelerate, so the drivetrain really takes ALL the load, where at low speeds in lower gears this wouldn't be true. It's a bit weird, but that's how I always think about it. That make sense?

 

There was a thread by 260DET and ezzzzz (not sure how many z's on that one) where they were both doing CV's on R180s using different parts. Search for that one and it should answer your R180 CV questions.

[Pop N Wood]

It is generally believed that CV's work over a wider range of angles than U joints. When the rear end squats, the angles between the diff and stub axles get more severe. The angle stresses the U joints more than it does CV causing the U joints to break. If the rear suspension stays in a straight line, that is when most guys say U joints are as strong as the CV's

 

As for 1st to 2nd vs. 3rd to 4th, you are probably putting the same torque (hence stress) on the driveline components either way. But it is a fact of physics that the faster a car goes the less it is able to accelerate. Thus the butt-o-meter registers a smaller push when accelerating at speed even though the driveline maybe seeing the same forces.

 

Maybe you just got a bad joint, too. I wouldn't get too worried unless it happens again.

 

BTW, beautiful car.

[zredbaron]

awesome. thanks, jon.

[Guest JAMIE T]

R180's with CV's are fairly common. I had a set for awhile. I pulled them from a 280ZX of unknown origin.

 

So, your NA L6 SPUN the tires at 80 MPH. In 4th gear? WOW...

I've had cars that would spin the tires enough draw smoke at that speed, but they were supercharged and made over 500 wheel HP.

[zredbaron]

Great explanation, Pop N Wood. Between your and the others' response, I feel like I have a much better picture of what's going on back there. Thanks.

 

Thanks for the compliment...I try and keep the car clean. I should update that picture, I've got an air dam now.

[zredbaron]

So' date=' your NA L6 SPUN the tires at 80 MPH. In 4th gear? WOW...

I've had cars that would spin the tires enough draw smoke at that speed, but they were supercharged and made over 500 wheel HP.[/quote']

 

well, ....I wouldn't say I 'spun' the tires at 80 mph. 2nd gear will spin, but not 4th. This was a chirp, i doubt a full revolution of tire slippage. more like a 'partial' spin. i've made considerable butt-dyno gains since my last real dyno run by opening exhaust, putting larger venturis in my carbs, and dialing in my jets. if i had to guess a number using my last dyno run as a reference, 230-250 rwhp, with really great throttle response coupled with my 4.37 drive ratio...so the accelleration is pretty good.

 

its a fun ride. the last thing i want to do is break it!

[johnc]

Probably a couple things contributed to the failure:

 

1. High half-shaft rpms.

2. Quick and sharp torque reversal (deceleration to acceleration).

3. Heat (from the high rpms).

4. Maybe an ill timed bump in the road.

[rudypoochris]

Just from experience I bet it is the quick decel then accel. Most likely, like others said, you let the clutch out (too fast for the speed I guess) before the engine was reved up, your tires lost traction briefly to catch up with the drivetrain, then you hammerd the accel which finally finished off the joint. So i agree with what the others said pretty much.

 

But, how much does your flywheel weigh btw? Also are you carburated or efi? Just wondering because maybe the engine bogged a little from all that gas you dumped when you floored it, so maybe the engine was trying to get back to a good AFR and get the rpms up. So it is possible that maybe your rpms at the time wernt as high as you are thinking.

 

Lastly u-joints should be aok. I can't remember where i read this, maybe JTR but someone recommended oem nissan u-joints because they are stronger then spicer u-joints maybe soemthing to do with grease fittings, i don't really remember and i could be wrong but look into it.

 

good luck!

[260DET]

When converting mine to 280ZX CV type rear half shafts, it seemed from a visual comparison that they would be considerable stronger than the stock cross type universal joints. Thats one of the reasons why the conversion was done

 

IMHO Spicer brand universal joints are not as good as the OE Jap ones.

 

EDIT first line

[zredbaron]

Just from experience I bet it is the quick decel then accel. Most likely, like others said, you let the clutch out (too fast for the speed I guess) before the engine was reved up, your tires lost traction briefly to catch up with the drivetrain, then you hammerd the accel which finally finished off the joint. So i agree with what the others said pretty much.

 

just when I thought I was understanding, now I feel like I'm missing something again. either that or i am being misunderstood as to what my feet were doing. either way, i'd like to clear it up...i want to know if i'm looking at something all wrong or if its just a simple miscommunication.

 

you say my tires lost traction to catch up with drivetrain, then i hammered the gas. this is where i think the confusion is....there was never a decel, the shift was as instant as it gets...i think any decel would be negligible: i pushed in the clutch, and yes, im sure there was a *slight decel* as the shifter went from 5th to 4th, no slip in traction yet...the clutch is still in, then i simultaneoulsy let off the clutch and mash the pedal. this is where the chirp occurs...definately under accelleration, not decelleration. this all happened in less than half a second. not much decel can happen in half a second with the clutch pedal in. drop in torque felt on the rear drivetrain, sure, but decel? any decel would be from drivetrain friction and road friction (wind resistance slowing car speed and therefore wheel rpm), the engine would not be doing a forced decel. this decel wouldn't be anything more than negligible for all intents and purposes. not in my train of thought, anyway.

 

But, how much does your flywheel weigh btw? Also are you carburated or efi? Just wondering because maybe the engine bogged a little from all that gas you dumped when you floored it, so maybe the engine was trying to get back to a good AFR and get the rpms up. So it is possible that maybe your rpms at the time wernt as high as you are thinking.

 

13 lb aluminum flywheel, carbureted. i did NOT raise the rpms and let out the clutch. the drivetrain was engaged at the same time the pedal was pressed. i assure you it was throttle response and not excessive kinetic energy at the flywheel. the setup is very torquey (sp?).

 

IMHO Spicer brand universal joints are not as good as the OE Jap ones.

 

really?! do you mean the 240Z or 280zx oem u-joints? or either? i think i'd rather find a way to do an r180 cv conversion rather than put in 280zx halfshafts...

 

thanks, guys.

 

(and perhaps I should be shot for this...but I'm tired of wondering what IMHO means...what does it mean?)

[Nismo280zEd]

No worries mate.

 

Yeah I have the same problem with my 280 halshafts, the webers produce gobbles of low end torque and the u-joints just can't take it. I don't think converting the R180 would be too dificult a challenge for a decent machine shop. After my wheel spacer failure i'm starting to wonder if I want to buy Ross C's billet CV adaptors of just have a local shop weld something up.

 

Best Regards,

 

Ed

BTW.. what jets are you running in yours now days?

[rudypoochris]

in my honest opinion = imho