Finally blew an axle.

[RebekahsZ]

This should probably be in drivetrain but most of my racing buddies pretty much stick to the Gen III forum. First trip out of the stable since switching to koni yellows and 28x10.5 MT bias ply slicks. Same 3.54 R200 CLSD and shortened Z31T CV axles as last year. Last year i was spinning the 26x8.5s at any track but the most immaculately prepped. Set konis full stiff (full rebound dampening) in back and full soft (least rebound dampening) in front. Put 15# in the slicks. Set 2-step at 3000. First pass: .539 rxn (.500 full tree), dead hook, 1.6 60', 7.18 at 99mph, straight as an arrow (oddly straight for bias plies). None of last years spinning, hook-spin-hook; no bouncing or porpoising. Second pass: dead hook, 7.22? Didn't like the dead hooking, so I pumped tires to 20# to reduce contact patch and allow a little wheel spin (that's what I was thinking anyway). After 5000rpm second gear burn out (no tire hop), staged, dumped clutch on the last yellow light and "BANG!" It was pretty unexciting in the car, but the track photog said the hood jumped up a couple inches. Pushed me against the back fence where the sprayer parks. Had me pull up trailer and winch it up. All the VHT about sucked the tires off my truck as I tried to avoid the groove as I went down the track. No oil leaks until I tilted car as it went up trailer ramps cleaned trailer up before pulling truck ahead. A circular spring (side axle seal spring) and some metal chunks were found at the line. Right axle is fine, left axle snapped but still in place, not flopping around. Looks like I snapped the splined portion of the inner CV, same as Josey was doing. It really sucks to have a steep driveway at times like this. Wondering if CLSD is fubar too, since it used to have 45# break away-would that make car moveable (it's not)? Jealous of Josey's old welded diff in terms of ability to get car up driveway. Lots if questions: air pressure too high, or just living on borrowed time after two years (tons of hot lapped passes) of living dangerously? May try to replace just that CV and do the repair in the street. Maybe it will rain, just to make life interesting. It seems to rain like hades everytime I break a driveshaft. If this keeps up all summer, car is getting back halfed this winter but will remain manually shifted.

Edited April 13, 2014 by RebekahsZ

[JMortensen]

The breakaway in the LSD is not enough to move the car if you lost a CV. It's also not enough to move it if one wheel is off the ground.

[RebekahsZ]

That's reassuring. Maybe I'm just out an inner CV. Jon, your axle shaft still looks great. Can inner CVs (the splined output stub portion) be heat treated or something to add strength?

[mistafosta]

Sadly, you are probably at the limit of those z31 axles with those types of launches. 2 step and sticky tires are gonna hit quite hard. Its been a long time but I had moser axles with z32 cv joints before, is that still possible with your setup or would it be a huge change?

[JMortensen]

I know they're already heat treated, and I know their CV shafts are heat treated HARD. Really hard. I didn't have the CV's tested since I wasn't going to make them. I think the best thing to do would be to either move to a better CV or to swap to a bigger diff. Solid makes a lot of sense for drag racing.

 

Joe @ Chequered Flag was trying to do a Porsche style CV conversion. I don't know if he's made any headway, but then you'd have a significantly larger CV with a 4340 double heat treated chromoly stub shaft for the diff. I think at that point you'd probably run out of things to break before the ring and pinion itself.

[RebekahsZ]

Gonna build up an axle today before pulling broken one. Is the driver side the short inner CV or the long one?

[EastTnZ]

On my 300zxt axle swap the drivers side was the short one. Your car looked awesome at the meet yesterday and those new slicks are massive.

[mattd428]

Just weld those gears up then you can drive on one axle all the time. Oh ya I've been there.

[SUNNY Z]

Time for that 8.8 SRA!

[ktm]

I know they're already heat treated, and I know their CV shafts are heat treated HARD. Really hard. I didn't have the CV's tested since I wasn't going to make them. I think the best thing to do would be to either move to a better CV or to swap to a bigger diff. Solid makes a lot of sense for drag racing.

 

Joe @ Chequered Flag was trying to do a Porsche style CV conversion. I don't know if he's made any headway, but then you'd have a significantly larger CV with a 4340 double heat treated chromoly stub shaft for the diff. I think at that point you'd probably run out of things to break before the ring and pinion itself.

 

Isn't Wolf Creek's setup also 930 based?  They state Porsche-type and using 4340 chromoly stub shafts.

[JMortensen]

Yes. Bolted to stock stub shafts and companion flanges.

[Domzs]

Just weld those gears up then you can drive on one axle all the time. Oh ya I've been there.

Too many times , Matt .  . But not anymore , right ?

[mattd428]

Nope now she sits.

[RebekahsZ]

Yeah, and I'm missing having a parking brake too, cause leaving car in gear to hold on a hill doesn't work with a broken axle. Since I have 7 R200s and 3 sets of CVs and 2 sets of shortened center bars, I'm gonna stay R200 a bit more-just too heavily invested. I rigged up a winch on the floor of the garage plus a couple of tow ropes to winch the car up my steep driveway (another special tool). So now when I break the driveline, whether it be a driveshaft or an axle, I will at least be able to get the car into the shop. Car is in shop now and I have tomorrow off. Will tear into it and see what we've got. Ordered a pile of output stub seals today.

Edited April 14, 2014 by RebekahsZ

[RebekahsZ]

Inner CV replaced. Car still down awaiting a diff output seal. Total damage: broken inner CV at the thickest section 1.25" diameter, slightly torn inner CV boot, some scratches and burrs inside diff carrier where the stub inserts, diff output shaft seal. Diff was slightly over-filled with friction modifier. I'm getting better with these axles. Wound up pulling passenger side axle also so that I could easily drive the broken stub out of the driver side (an LSD has no cross shaft), then put passenger side axle right back in. De-burred carrier. And side seal sealing surface with dremel tool. Trusting any metal chunks to fall to bottom of diff oil. Put axle on vice, mounted on shaft. Mark location of boot. Cut off old torn boot. Steady tug on inner CV while smacking hard with metal 3# shop sledge. Removed inner CV from donor axle same way. Clean out donor inner CV with gasoline and clean, clean, clean then regrease. Easiest way to regrease is to squirt grease into female splined inner CV, then insert splined axle shaft into hole to force grease past ball bearings. Repeate until grease is clean. Put new CV boot on shaft (Ive forgotten this before). Put inner CV on splined shaft. Take to press and have wife slowly press assembly while I massage c-clip into groove. Secure boot with big hose clamps.

[SUNNY Z]

Well Keith, consider yourself lucky.  I had to remove the diff and pull the cover both times mine grenaded.  Couldnt drive it out from the pass. side.

[RebekahsZ]

I have been lucky for two years and my luck seems to have met its match with the 28x10.5 tires. I don't think anybody makes a 28" that is any narrower?? I will look but I don't think so. I need the 28" tall tire for gear ratio, but I think I might be willing to give a little on traction if it lets me hold up. I was pulling occasional 1.4 60' on the 26x8.5s. SunnyZ, I guess each diff has its pros and cons: a welded diff lets you one-leg it home and the CLSD lets you drive out broken a LR since it has no cross shaft. Learning, learning, learning. Who knows, this may have been propagation of a crack that started last year on the smaller tires.

[RebekahsZ]

Pics.  I had to  put an ATV 3000# Harbor Freight winch in the floor of my shop to get the car up the steep driveway (not enough folks from Sunday School showed up for Sunday night coffee)!  It worked like a charm.  Also put my wife and my new Harbor Freight press to good use pressing the CV onto the axle shaft.  This worked a lot better than the 2X4 and hammer method.  The trick is guiding the c-clip into its groove as you are starting to press them together.  Also, it helps to have flipped the outer cage so that the shaft is directly underneath the grease cap so that when pressing on the center of the grease cap I was actually pressing on the end of the shaft itself.  If the cage isn't flipped, there is a risk of bending and ruining the grease cap and they aren't available anywhere that I know of.  In the pics of the broken axle, the seal spring and the little chips were found on the ground at the track where the breakage happened.  Using hose clamps for boot retention made reassembly really easy-fighting those fancy CV clamps that come with the boots is a pain.

[RebekahsZ]

Axle seals came in but the Advance Auto part number delivered 6 special order, pre-paid R180 seals (which are too small). AutoZone can't get them, Rock Auto's pictures looked like they might be the wrong part too. Finally ordered from Black Dragon and paid for 2-day shipping air. Stock up fellas, these things are getting as hard to find as 22 shells. I ordered 10.

[RebekahsZ]

Back on the road. Drove car down to a swsp meet in town just to get the VHT and rocks off the tires. Believe it or not, the hardest part to source was the axle seal! Hoping to hit junkyard next Sat to build up a war chest if spare axles. And waiting for wfritts911 to finish his 8.8 conversion.