Broken halfshaft experiences?

[sims76]

Most agree that a driveshaft loop is a worthwile safety precaution on higher hp cars, but I don't often hear much discussion about the danger of a broken halfshaft....

 

In the past I have had my halfshaft bolts loosen enough that I could hear them clunk. Does anybody have any experience with a halfshaft letting loose at highway speed or under hard acceleration? Just wondering if it would rip through the floor, jam a wheel, etc....

[Pennyman]

I think what usually happens is thr U-joint will break. I had this happen once, but I think it was because I had just got the U-joint replaced and it was defective. Luckily the body of the joint cracked, but didn't give way. If it had given way, the halfshaft would start wreaking havoc on the wheel well. I've never heard of this happening, but in theory it is possible.

 

You bring up a good point about the halfshaft bolts, but as long as those are tight, I don't think shearing all 4 of them off would be a problem, hehe.

[510six]

I broke and axel once launching on slicks and a U joint once at the track doing the same thing.I got out of it both times before doing any real damage.

[stony]

with a welded diff i guess it wouldnt be as bad as with a diff. i broke several on launch and that split second it takes to get on the clutch it tore out the brake line put a couple dents in the floor and then lodged itself in the control arm ( azc ) Was a bitch getting everything apart. cant imagine doing that at hiway speeds.

 

I think if i had stuck with the IRS halfshaft hoops would have been installed for safety

[John Scott]

This old post is a blast from the past.Posted by 1fastz 9.76@ 149.6, I guess for some broken 1/2 shafts was just another day at the races:

 

"anyone gone faster then me yet while still independant rear?

 

--------------------------------------------------------------------------------

 

.......IM sure with the same motor and the large shot 8.60s is doable with the 400 shot.

 

I tried makeing some 350 horse seting passes but after breaking 7 half shafts when I hit the bottle in second I gave up. It got old pushing the car back of the stageing lane from half way to the eight with a broken half shaft heh."

[Ben D]

I've broken one half shaft, I'm using a Z31T IRS with stock Z31 T shafts with a manual gearbox, and if the halfshafts break, they break on the launch. However if you can preload the driveline a little, they seem to hang in there, its the inertia shock of the clutch dump which does it. Furtunately you're doing 0 mph when it happens. They break at the root of the outer CV spline car in my experience, but I have only broken 1 so far, and this set I have in there now has done 25 x 9 sec runs and a best of 9.12 with 1.33 to 60 ft, so they are impressive for stock pieces.

 

I've said to myself if I break another one, it is time to go to either a GTR style half shaft and CV (bigger splines), and/or get a set made from 300M. With both bigger CVs and the 300M shaft, I would say mid 8's would be attainable and reliable with my combo (would need more power then)....

[Ben D]

PS when the halfshaft broke, the car still drove down and back on the LSD (which is shimmed pretty tight), and since it broke where it did, the CV boot held it in alignment so it damaged nothing. Lucky I suppose.

[jnjdragracing]

This old post is a blast from the past.Posted by 1fastz 9.76@ 149.6' date=' I guess for some broken 1/2 shafts was just another day at the races:

 

"anyone gone faster then me yet while still independant rear?

 

--------------------------------------------------------------------------------

 

.......IM sure with the same motor and the large shot 8.60s is doable with the 400 shot.

 

I tried makeing some 350 horse seting passes but after breaking 7 half shafts when I hit the bottle in second I gave up. It got old pushing the car back of the stageing lane from half way to the eight with a broken half shaft heh."[/quote'] John , I went a 9.21 @ 153 mph in the quarter, on stock halftshafts, and a 5.82 @123 mph in the 1/8th. I wanted to go into the 8's on stock stuff. I rescently upgraded to CV axles. I am still shooting for the 8's . Jerry

[Pop N Wood]

I think the main purpose of a driveshaft loop is to keep the car from pole vaulting on a broken driveshaft. Not really an issue with half shafts.

 

Don't see how a single loop of steel will keep a shaft from beating the snot out of the tunnel.

[blueovalz]

The key is to make sure the loop is as tight around the driveshaft as is possible without making contact during normal suspension movement. With the IRS suspension, this is made easier because of the minimal movement of the differential as compared to live axle cars. And if the tranny and the diff are solidly bolted in place, the safety loop could have as little as .100 gap around the driveshaft (must take chassis flex into consideration). When you leave too much room between the loop, and the shaft, the beating the loop takes is increased dramatically.

 

In regards to the U-jointed shafts, I believe one key to longivity is to set the suspension up so that you have the axle shafts in a straight line during the transition to the infamous "squat". Obviously this is a compromise, and any Z that is lowered a good bit will already show angularity in the shaft joints, and then a high torque squat coming off line will make the situation even worse for the U-joints. One thing I did was raise the differential by about 1" (the upper subframe above the differential is an issue here) which helped straighten out the shafts.

[Cable]

I am still running the factory u-joint halfshafts in my 280z with my 454. I still haven't really hammered on it, but I have done a quick 10 brake-stand. I think mine will live as long as I don't hookup.

[Guest Mike]

I've often wondered why shaft loops are designed as simple U shapes when it seems better to have a full circle around the shaft. It seems like a full circle would help prevent the shaft from beating the underside of the car to pieces.

 

Something like this...

 

http://forums.hybridz.org/attachment.php?attachmentid=1524&stc=1&d=1161551579

[ZDrifter]

I have broken 3 u joints with the stock L28 motor in the car. I know two of them were bad because they broke while I was backing into my garage. But the other one i completely snapped diagonally agross the center cross. If you set a brand new u joint on the ground and picture it completely in half thats what mine did. I was in a parking lot showing off and there was water on the ground and I started burning out, held it, and let off the break to pull out into the street and the shock of pulling onto the street (stock springs and struts) completely snapped it, id say the tires were spinning a good 40mph. Anyway NOT A GOOD SOUND!!!! That half shaft spun in the wheel well and only gashed the inside of the wheel well then lodged itself in the control arm. I had to beet the hell out of it to get it loose but after that it was a 2 hour job of fixin it. Thats my story but since I did the RB swap i have been waiting for any hard driving until I get stronger components. About the driveline loop. Only purpose is to prevent it from pole vaulting like pop n wood said. If you had a complete circle around the driveline it would be hard not to interfere with the normal movement of the driveline and also if the driveline breaks the stress that the driveline would put on it might break the tight loop itself in my opinion. Better to have minor gashes in your floor then a driveline right next to you in the car. I had two driveline bolts fall out or break after going through the grapevine in cali and its very bad vibration, good thing i stopped cuz the third was on its way. But those are my destructive stories haha, im definitly looking into stronger components for drifting.

[blueovalz]

{quote] I've often wondered why shaft loops are designed as simple U shapes when it seems better to have a full circle around the shaft. It seems like a full circle would help prevent the shaft from beating the underside of the car to pieces.

 

This is because these are made more for live axle cars, which allow a lot of up-and-down movement. Thus the loop must be elonged in order to keep the movement as restrictive as is possible. Our IRS set-ups could use a more round arrangement, but the propeller flange still moves up and down a bit.

[John Scott]

I think the main purpose of a driveshaft loop is to keep the car from pole vaulting on a broken driveshaft. Not really an issue with half shafts.

 

Don't see how a single loop of steel will keep a shaft from beating the snot out of the tunnel.

 

I know we're talking 1/2 shafts, but had driveshaft fail in my 68 442 at the end of the 1/4. Had me plastered againts the door while my center console was leaping off the trans hump. Shaft tore in 1/2, but loop did its job. I worry less about what it would do to the tunnel as what it would be like inside of a blender by not having one.

 

"John , I went a 9.21 @ 153 mph in the quarter, on stock halftshafts, and a 5.82 @123 mph in the 1/8th. I wanted to go into the 8's on stock stuff. I rescently upgraded to CV axles. I am still shooting for the 8's . Jerry"

^^^^^^^^^^^^^^^^^^^^^^^^^^

I'm amazed at what the rear will handle. Heard stock 150 hp cars breaking, must be due to limiting squat.

[dustin280zx]

manual = driveline parts breaking

automatics are ALOT easier on driveline parts

[dustin280zx]

jnjdragracing, are you using the cvs from a 280zxt?

[sweetride2go]

i guess im reseructing an old thread here, but does anyone have pictures of a broken halfshaft??? preferrably the earlier, u-joint style, halfshafts... is it always the u-joints that let go, or do they ever break in the middle???

 

thanks

[jnjdragracing]

i guess im reseructing an old thread here, but does anyone have pictures of a broken halfshaft??? preferrably the earlier, u-joint style, halfshafts... is it always the u-joints that let go, or do they ever break in the middle???

 

thanks

I have broken my share of haftshafts, in my cases I sheared off the caps nearly always on the driverside inboard joint, on the starting line. At SEZ6 I broke both haftshafts on the second pass. we put new ujoints in and raced the rest of the afternoon.On the lower A arms we cut metal out (1/8th'" thick) and covered the opening so if and when a halfshaft cut loose it wold not fall into the arm and bind up. Last year we converted to the 300 Turb CV axles and have had no breakage, which is a good thing. We have some pictuires of the rearend on our web site, jnjdragracing.com

You might be able to see the metal on the lower control arms. Jerry

[cygnusx1]

got wheelie bars yet?