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280zxT cv shafts BROKEN !!


MAXIMUS

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Hi all.

Can ANYONE tell me what other options I have to keep my rear shafts from shearing off?

I converted my 81 280zx U-joint half shafts to turbo cv's .

Still breaking at the track,on a street radial,and no burnout.

I am shearing the shafts righ off!!

Help!?

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ok,so here's what I have: 406sbc.It dyno'ed 485hp/485ftlbs torque.

T-56 trans,tokico ILLUMINA shocks,big sway bar/urethane bushings.

16inch Falken radial tires(255/50/16)on rear.

280zxt cv shafts that I just bought and did the conversion from U-joints because it was supposed to be stronger? I think,lol

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The 280ZXT is a 'tripod' joint, not a CV. For a true CV style, you have to go to at least a Z31 "Double Offset Birfield Joint" in Nissanspeak...

The Tripods ARE stronger than the U-Joints. Seems the problem isn't the joint that is breaking (as the trunnion in a U-Joint would shatter), it's now the next weakest link: Axle Shafts away from the Tripod. I have seen this in L6 Powered cars as well if they hook. Could be a stress crack. Were the axles/joints magnafluxed, Zyglo Inspected, or even spot-chek'd before installation to be sure no cracks at the radius were present?

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Guys,

As MAXIMUS mentioned, he was destroying U-joint half shafts in the past, (posted pics of those then), and now has switched over to the CV Joints and is now breaking those. This is on a S-130 280-ZX with the semi trailing arm rear suspension. As for posting pics, I don’t think that will do him any good other than give us some entertaining pics of busted CV joints to admire so we can all nod in agreement saying "Yeup, their busted alright! "

 

MAXIMUS,

I think if you went to the beefier 300-ZX Turbo half shafts, they “might” hold up, or at least hold longer than the 280 ZX-T shafts, but honestly, I feel if you really want to “fix” this issue, your only option is to get the “squat” during launch under control. As we all discussed in depth in your other thread, the U-joint and CV joint half shafts are more than tough enough to handle your power and available traction, but because the semi trailing arm squats so bad, your half shafts are now going through a wide range of angularity and THAT coupled with the torque you are producing/traction is causing the shafts to bust.

 

I honestly feel that the half shafts are not the issue here, the angularity they are going through IS.

 

Options as I see them for your situation;

 

1) Convert to solid axle. Pros are obviously beefier parts and you can take advantage of the torque reaction to obtain more bite on launch than IRS could EVER deliver, but only because of torque reaction.

 

2) Switch over to another IRS configuration that isn’t prone to so much squat.

 

3) If keeping the semi trailing arm is a must, either Install a “z” bar to help minimize squat with the semi trialing arm, or alter the geometry of the control arms for more anti-squat.

 

 

Anyone else have any ideas?

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I think the squat is somewhat overblown. If a VW Bus Transaxle and CV joint can handle full sand Paddla-Traks behind a Hilborn Injected Chevy with a suspension that squats probably 30 degrees when digging in...a 15 degree squat on a ZX should be more than managable.

 

Sure, you can up the spring rate, or even damp the hell out of it with shock valving...but a CV should not experience any different loading at 30 degrees of angularity than at 0 degrees (if properly clearanced).

 

Really, the Tripod Style Axles are known to break on N/A Powered S30's with good hook at drag races...so going CV is the only step left. To make them survive all you need do is clearance the cages like the VW guys have been doing for decades.

 

With a clearanced CV Cage, and properly clearanced axle ends, they should be able to hold all torque from 0 to about 30 degrees. Some of the really articulated cars will look to have near 45 degrees offset in some circumstances. Look to the transaxle on Spencer Lowe's old off-road truck and you will see plenty of CV angularity and 'squat' with gobs of torque transmitted and shock loadings to boot.

 

That is the way I'd go---clearance a REAL CV, and not try to make the Tripods Work. I believe Frank 280ZX has installed a complete Z31 Subframe (five lugs and all) into his 79ZX, and I have seen both Z32 and Skyline Subframes under S130's. I do have photos of some of these setups taken in 2004 from the 'japanese contingent' at the National Z-Con, but won't have access to them till the weekend. PM Me with an e-mail addy if you want me to shoot you some photos. Frank 280ZX posted some of the conversion photos somewhere...don't know if they were here, classiczcars, or zdriver galleries. But they are online.

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This could be something as simple as the tires getting caught up in the wheelwells.

 

Good Point! I know we watched JeffP's tires move forward in the wheelwells during dyno sessions. The ONLY thing that could be causing that in his car is trailingarm flex---his subframe is solid-bushed, and when he made the bushings, he moved the wheels BACK in the wheelwell almost 1/2"--and we were measuring close to 3/8" deflection!

 

Trailing arm flex may indeed be causing something there with your instantaneous torque loadings. If the wheels were binding against the body, there should be some clear evidence...

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Whether or not squat is causing the breakages it would be a good idea to get that under control, at the very least to reduce the camber change effect on tyre to ground contact. This can be done by changing the semi trailing arm's swing angularity, common thing to do on 510's and BMW's.

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  • 1 year later...
Hi all.

Can ANYONE tell me what other options I have to keep my rear shafts from shearing off?

I converted my 81 280zx U-joint half shafts to turbo cv's .

Still breaking at the track,on a street radial,and no burnout.

I am shearing the shafts righ off!!

Help!?

 

MAXIMUS,

Did you ever get your CV Shaft issue handled? Just curious what solved the problem.

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