• Hi Guest!
    You can help ensure that British Car Forum (BCF) continues to provide a great place to engage in the British car hobby! If you find BCF a beneficial community, please consider supporting our efforts with a subscription.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

Ruby Red Car go BANG

Share this page

Sarastro

Sarastro

Yoda
Silver
Country flag
Offline
Well, it finally happened--my first major breakdown. Let out the clutch on a slight hill, making a right turn, and I heard a solid BANG from the rear. "That doesn't sound good," I said to myself as myself and LBC coasted to a stop, just short of the trolley tracks I was about to cross. With the help of a couple young guys standing nearby, I got it into a parking lot and called AAA.

AAA guy was very nice. "Wow, that's a really nice car," he exclaimed when I told him it was a '60 Healey Sprite. "You must be having a lot of fun with it."

"I was until about five minutes ago," I replied. He laughed.

Sigh.

Fortunately, I was only a couple miles from home. While waiting for the tow truck, I determined that the drive shaft was turning just fine at the rear end, only problem was that the wheels weren't turning in response. Definitely not the most desirable mode of operation.

So, what do you guess--broke the drive pinion? Or, couldn't a broken axle do this, too? No grinding or other noises, just a BANG and car no go no more. In any case, I'll tear it apart as soon as I get time, maybe this weekend, maybe not. Soon, I suspect, I'll be in the market for a new rear end....
 
Sorry to hear it. At least now you've got your first breakdown out of the way. Wish I had some advice, but I'll have to leave that to wiser folks than me.
 
Steve,
I haven't had that problem because my car is barely off of the saw horses. However, it is my understanding that a common problem is the axle shafts. I believe that this is why many go to the hardened shafts. But, I am ready to be wrong here. WHat do others think?
 
Yes....very high chance of broken axle.

I broke 5 of them last year in my racer.

Generally (but not always) the axle will break on the outer end, which is a good thing. Usually, you just need to remove the brake drum and the axle end plate will come off, leaving the broken shaft roughly flush with the rear axle bearing. If there's enough of the axle to grab with a big pliers, you can just pull it out. If it's flush, you may to play with a bit to get it out. A strong magnet might get it out.....or just use a thin screwdriver to try to "pick at it" and get it out.

If the axle is broken at the inner (spline) end, it's a more difficult job. You'll need to remove both axles, unbolt the driveshaft and remove the differential from the rear axle. Still, this is not all that hard.

The stronger "race" axles may help.

The ring and pinion gears are pretty tough....it's rare to break them.
G'luck!
 
It'll be an axle, agreed. Likely an outer end. I'd say replace both sides with the stronger ones now.
 
broken axle ... is my guess ... did that twice in the early days when i actually drove the car. the pinion was fine in both cases .. so i am imagining the same for you.
 
An unfortunately quite common affliction of the Spridget. Definitly an axle! They tend to break at the outer end due to spirited cornering, and the inner end after too many jack-rabbit starts which will twist the axle like a corkscrew!!
 
To bad about the breakdown. I'll be interested to hear your experience with replacing the axles as I'll probably do the same to my BE. I'm putting in a 3.9 diff to replace the 4.2 and wile I'm there Ii'll put in the hardened axles.
Good Luck...keep us posted.

(Don't forget to drain the diff. before you work on it!
 
I vote axle too. I've broken two and never been fortunate enough to have them break at the flange. Always at the splines. One was at college so there was no money for tow trucks or garages. I had to fix it in the parking lot that I pushed the BE into. It's not a hard job. Just take your time and if it is broken at the splines, make sure you don't leave any small pieces of metal laying in the bottom of the differential case.

JPF
 
You can usually pick up some used axles cheap on EBay, or buy some of a little better quality like winner's circle.
 
Thanks much for the comments. Yes, I've noticed that there always seem to be a couple axle sets on ebay at any particular time. Rear ends, too. I've pulled an axle once before to replace a hub seal, so it shouldn't be too difficult.

One follow-up question; if it is the differential (or maybe even if it isn't), I'm toying with the idea of putting a 3.90 into the car instead of the 4.22, mostly for the usual reasons. The question: how badly does this affect accelleration? I'd expect a modest effect, maybe noticeable to the driver but not terribly significant in practice. I'd be interested to hear other people's impressions of that.
 
I vote for the axle, but I would definately say the inner end. I've broken many of those in the old days, and never ever broken an outer end, even in the race car.

If it the inner end, you have to pull the brake drum and axles anyway, so you will know for sure. Then the diff (pumpkin) must come out. 4 drive shaft bolts, both axles and 10 pumpkin nuts. Make sure to catch the oil. Then pop out the axle stub and reassemble.

I did one of these in 10 degree cold on the ground and 10 miles from home my first time. And then the pumpkin wouldn't go back in because it was too warm - large to fit. A few minutes cured that.

Tip, It's easier to fill the oil through the axle tube on one side insted of through the filler plug.

Have fun.
 
I think people are guessing outer end since he said he was turning.
 
This morning, I pulled off the right rear drum. As several of you suggested, it was a broken axle, snapped at the outer end. Good call, guys! Thanks for the help.

The first three figures below show what I found when I pulled the drum. The flange practically fell off, and the axle came out easily. Now, the interesting part: this appears to be a classical fatigue failure of the metal near the flange. Apparently, one can recognize such failures by inspection of the break; see https://www.sv.vt.edu/classes/MSE2094_NoteBook/97ClassProj/exper/meyer/www/meyer.html

Anyway, fatigue failures begin with a scratch or some other kind of feature that concentrates the stress, a crack forms, and propagates as the part flexes. Often the crack moves a bit, then stops, leaving telltale ridges. These extensions of the crack leave a relatively smooth region, then there is a rough area where the part finally fractured. I hope the pictures can show this, but it's quite clear from the break. You can see some "stop marks," but they are, as one would expect, circumferential, not like the ones shown in the link I've provided.

OK, so what? It seems that periodically checking axles for cracks near the flange (and splines, for that matter) might be a good way to prevent these failures. Also, simply replacing the axles periodically, especially with later ones, which, I'm told, are stronger. They're not all that expensive, especially compared to a long-distance tow.

The last two figures compare the two axles. I plan to replace both. The unbroken one from the left side looks much more nicely made--but the difference tells me that this isn't the first axle replacement. The broken one is labeled "Borg Warner." I wonder which, if either, is original? Also, the unbroken one looks much more sensibly made at the flange--note the nicely coved transition between axle and flange, which minimizes stress risers. Before I install them, I'll check for stress cracks (as best I can, anyway; they can be really hard to see) and make sure there are no stress risers at the joint.
 
Steve, ain't failure analysis fun!?
I remember back in 'the day', carrying a spare axle with me at always! I haven't snapped one in a long time.
The Borg Warner axle is definitely not original.
A dye penetrant kit is a good way to check for cracks, but periodic Magnaflux checks would be a better way. I don't know how feasible that would be for you, so maybe the penetrant route would be the way to go.
A good set of high strength axles will run about 400 bucks.
Jeff
 
The primary reason for axle breakage at the outer end is flexure caused by the poor design of the axle. These "semi-floating" axles actually help locate the outer axle bearing, taking much of the side loading that comes with hard cornering.

One solution is to switch to double-bearing outer hubs(which greatly reduce axle flex).....or switch the rear axle to a different design. The stonger race axles will help, but the double-bearing hubs are more important. I was breaking (stock) axles left and right until I put in double bearing hubs. I still break an occasional one here and there (I broke 3 at the '06 Pittsburgh Vintage because of a problem with the hub bearing carrier.) My long-term plan is to switch to a different axle (probably shortened RX7....partly to get the limited slip, disk brakes and better rear axle oil seal ), but that has to wait until race-car #2 is done. The double bearing hubs for a Sprite are about $600 a pair and the two race axles are about $500. Limited slip is about $1300. I can build a shortened RX7 axle with the impovements mentioned (and with a Sprite wheel bolt pattern) for about $500.

And yes, drag-race starts will snap Spridget axles more often at the inner (spline) end. I saw one fail in a race Bugeye at a standing start hillclimb a few years ago. I've broken around 20 in my life.....two at the inner end.

For you, with a moderate street car and street tires, the race axles and single bearing hubs will be OK, but changing the outer axle bearings every couple of years will help too.

The race axles are often called "two piece" due to the fabrication method. I've never seen a Borg-Warner Sprite axle, but I've heard that BMC fitted a good number of "German axles" in the late '60s that were supposed to be superior.
 
I'm an electrical engineer, not mechanical, but the mechanical issues still fascinate me, and I try to learn what I can. Thanks for the info on the Borg axle; I suspected it was not the original. As I look at it more closely, there is a small stress riser right where it broke--the coved joint where the axle meets the flange is really not properly rounded--there is a step and then some minor rounding. Guess where it broke! The moral: don't buy cheap replacement parts for critical applications.

By the way, who makes high-strength replacement axles? Anyone have a favorite product and supplier?
 
Thanks so much, guys! I think I may go for a set of the improved axles, even though I'm looking at something like $600. I'm putting quite a bit of energy into making this little gal reliable, so maybe that is within reason. Even for a cheapskate like me...!

I also like the idea of two-bearing hubs, but maybe that's a little beyond what I'll do with a car that is, after all, a stock road machine. For the way I treat it, I kinda think that improved axles should be enough, although I do understand the issue regarding the hubs.

I'd like to add that I'm really impressed with the people on this forum--genuinely helpful and friendly. I participate in a classic-bicycle email list, and, wow, you wouldn't believe the egos! This place is extraordinarily pleasant, more so by comparison with my other experiences.
 
Back
Top