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Half Shafts - Hardened
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Matthew E. Herd
Jedi Warrior
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That may be true, but even so they're not THAT strong. The casting number on later axles is ?803? or something like that, and it's EN17 grade steel (I have no idea what that equates to in actual tensile strength). I understand this is a higher grade steel, but lower than the much sought after EN19, used in some A series cranks. If Huffaker still sells competition axle shafts, I believe they're the best price on the market. Replacements could be made for about 450 a set, (about what Huffaker quotes on their slightly dated webpage) or so I've been quoted from either Moser or Dutchman (I can't remember which). It's generally easier to purchase than re-invent. However, those axles should be adequate for any duty.
As an aside, despite their generally poor reputation, the standard axleshafts have lasted probably 15 autocross events for me, with no evidence of failure thus far. All but perhaps 3 events were on Yokohama A032R race tires. I have blown a 1500 transmission and U-joint (simultaneously) but the axles haven't given trouble.
As an aside, despite their generally poor reputation, the standard axleshafts have lasted probably 15 autocross events for me, with no evidence of failure thus far. All but perhaps 3 events were on Yokohama A032R race tires. I have blown a 1500 transmission and U-joint (simultaneously) but the axles haven't given trouble.
Matthew E. Herd
Jedi Warrior
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I don't know (but others will) what year they upgraded the halfshafts, but I do know that the 1500 shafts should be fine at that power output. I guess my output to be between 110-120 Hp, with excellent torque to match, so 90 hp from any of the A series units should be fine (as the torque is generally lower -- but the gear ratios for a bugeye are marginally higher at 4.22 versus 3.909).
Matthew E. Herd
Jedi Warrior
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One more comment, since they're quite cheap and so darned easy to change, I would get a spare set and not worry about it. (I should follow my own advice, as I am currently sans spares).
tony barnhill
Great Pumpkin - R.I.P
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I've a friend here in town who's originally from Ireland - he drives the youknowwhat out of his Midget....he's always out here pulling axles out of the dead Midgets in my MG Graveyard...keeps them in his garage as he regularly breaks an axle!
aeronca65t
Great Pumpkin
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I'm not sure that the 1500 car has better axles. I've never heard that.
I did hear that certain, older 1275 cars (around 69?) had German-made axles that were supposed to be better, but that's a rumor...not sure it's true.
I doubt the axles are "hardened". They are likely to be different material and the attachment process for the hub plate is different (to make them stronger).
There is supposed to be stainless steel axles sold in the UK (I recall seeing them in a Brit magazine).
At any rate, I agree with Jeff: the double-bearing hubs make a big difference. I haven't snapped an axle (they're stock) since I switched to double-bearing. This is about 30 hours of hard road racing with the same tires that Matthew is using. My 1500 likely has about 80 HP.
One thing: you might still snap axles (often on the inside spline) if you do a lot of drag-race starts. The double-bearing hubs support the outer part of the axle better so that there is less flexing (and failure).
I snapped a race axle on a single-bearing hub.
You can get the race hubs from Winner's Circle or Acme Speed. Acme had them for about $425 a while ago.
https://www.acmespeedshop.com/autoparts.html
I did hear that certain, older 1275 cars (around 69?) had German-made axles that were supposed to be better, but that's a rumor...not sure it's true.
I doubt the axles are "hardened". They are likely to be different material and the attachment process for the hub plate is different (to make them stronger).
There is supposed to be stainless steel axles sold in the UK (I recall seeing them in a Brit magazine).
At any rate, I agree with Jeff: the double-bearing hubs make a big difference. I haven't snapped an axle (they're stock) since I switched to double-bearing. This is about 30 hours of hard road racing with the same tires that Matthew is using. My 1500 likely has about 80 HP.
One thing: you might still snap axles (often on the inside spline) if you do a lot of drag-race starts. The double-bearing hubs support the outer part of the axle better so that there is less flexing (and failure).
I snapped a race axle on a single-bearing hub.
You can get the race hubs from Winner's Circle or Acme Speed. Acme had them for about $425 a while ago.
https://www.acmespeedshop.com/autoparts.html
jlaird
Great Pumpkin
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Is this the spot. Story time.
One day at work I got a call from my wife, this was in Atlanta back about 1974. She said I'm over here bla bla and the Sprite won't go. I said what do you mean won't go. She said I let the clutch out and it won't go. Hmmm, ok I come and we'll tow it home.
This was the first and last time it was ever towed home in 20 something years by the way.
Got it home and found of course that she had snaped a shaft. Of course she did not do it really but I have never let on to her that she did not do it. Hehe.
Had an extra from a parts car, off to work in the morning no problems, going like heck as usual on my cross country back road route.
Oh yea there were several of us that took that same route, good fun on the way to work when we happened to meet.
One day at work I got a call from my wife, this was in Atlanta back about 1974. She said I'm over here bla bla and the Sprite won't go. I said what do you mean won't go. She said I let the clutch out and it won't go. Hmmm, ok I come and we'll tow it home.
This was the first and last time it was ever towed home in 20 something years by the way.
Got it home and found of course that she had snaped a shaft. Of course she did not do it really but I have never let on to her that she did not do it. Hehe.
Had an extra from a parts car, off to work in the morning no problems, going like heck as usual on my cross country back road route.
Oh yea there were several of us that took that same route, good fun on the way to work when we happened to meet.
ChrisS
Jedi Knight
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I have a set of the BTA806 axles (which I believe are the stock axles for most if not all 1275's) and a set of the BTA940 axles which are supposedly nitrided; as I understand it the BTA940 axles were a factory option. I have not looked at them side by side to compare the flange connections, but if folks are interested I could do some digging. The bugeyes had BTA501 axles which came on the 948 and 1098 cars. These may be weak on a higher HP car. I would say that the double bearing hubs with factory BTA806 axles would probably be better than the nitrided axles with factory hubs, IMHO. At a minimum make sure you have the BTA806 axles.
jollyroger
Jedi Trainee
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I maintain a number of sprite racers, Both autocross and road racing. If you are running sticky tires,or high HP, or jerking your car around on an autocross, or road racing and you can afford it, double bearing hubs are the way to go. I have found that even the stock axles, if they are not flawed or cracked previously will live a long life with double bearing hubs.( I have an set on my fast sprite with double hubs 4 years racing no problems) Just putting stronger axles in the old hubs will not work. Flex under side loading involved in the stock stuff will break the axles at the flange point. If you try using some of those axles that are splined on both ends and held on with the big nuts(you know the ones from Mini Mania) you will find they won't work without a double bearing hubs too. Ask me how I know.
By the way an easy check for flaws in axles is to hold em by the splined end and whack the flange end with a nice piece of steel. If it rings nicely it is good, if it goes thunk or doink, give or sell it to your enemy.
There are some tricks to installing double bearing hubs.
By the way an easy check for flaws in axles is to hold em by the splined end and whack the flange end with a nice piece of steel. If it rings nicely it is good, if it goes thunk or doink, give or sell it to your enemy.
There are some tricks to installing double bearing hubs.
Matthew E. Herd
Jedi Warrior
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As to horsepower numbers, Nial's setup is about the same as mine (perhaps a little less tweaked, but basically the same). I compare to other numbers (probably optimistic) and come to my own guesses. My numbers are not dyno proven, and I recognize that they're probably a bit on the high side. As I recall, my intake setup is different from Nial's, but we're using the same cam, and similar CR's (10.5:1 vs 10:1), etc. I also use the 1.55:1 rockers, but I don't know if Nial's does. Engines sure are fun (but expensive)!
I've been meaning to investigate double bearing hubs kits. From the pictures, I don't really understand how the Acme unit installs. I remember, Nial, that you had a custom setup, and was curious how that turned out. Comments please!
I've been meaning to investigate double bearing hubs kits. From the pictures, I don't really understand how the Acme unit installs. I remember, Nial, that you had a custom setup, and was curious how that turned out. Comments please!
jollyroger
Jedi Trainee
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The guys that sell the double bearing units will tell you to check your axle housings for straightness. They say the axle needs to be straight. You can do this by mounting the db hubs with wheels and tires and putting the axle assembly on the ground and rotating the axle unit while holding to wheels still. Measure the distance across from tire to tire using a point on the treads of both tires while rotating the housing if the distace changes significantly during rotation then the housing is bent. I have found in the past that there is a lot of slop in the diff axle spline area. Given this slop, I don't think this runout really matters unless it is really excessive.(1/2 inch or so) In fact I have acually in the past experimented with bending the housing to get some amounts of negative camber without any ill effects. Your results may differ.
Oh, by the way my car is running 14 to 1 compression with well over 300 psi pressure readings.
Oh, by the way my car is running 14 to 1 compression with well over 300 psi pressure readings.
jollyroger
Jedi Trainee
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I guess I could, with the right jets. I hadn't thought about that. My 13 year old son races a 600 cc. mini sprint car. It runs alcohol, guess I could bowwow some of his fuel.
The sprite makes pretty good torque. Tough on the bearings. Spins to about 85 if I want. Usually keep below 7 grand. Lot's o fun on the track. I run 100 av gas(sorta) with no problem.
The sprite makes pretty good torque. Tough on the bearings. Spins to about 85 if I want. Usually keep below 7 grand. Lot's o fun on the track. I run 100 av gas(sorta) with no problem.
Matthew E. Herd
Jedi Warrior
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I think the trouble with your measurement technique is that the hub surface and the wheels themselves must be perpendicular to the axis of rotation. I, for one, know that my stock rostyle steel wheels are NOT straight! I think you're right, in that the mis-alignmnet is probably not enough to worry about.
As per a discussion about fully floating versus 'live axle' (although I always referred to a 'live axle' as anything that wasn't independently suspended in the rear), it would seem that fully floating requires that the hub be on bearings, while the axle shaft merely attaches to it. It would seem, that if the straightness of the axle housing is of great concern, they must be converting to the non-floating type rear, where the bearings ride on the axle instead of the hub itself. I believe I would prefer to retain the floating configuration.
As per a discussion about fully floating versus 'live axle' (although I always referred to a 'live axle' as anything that wasn't independently suspended in the rear), it would seem that fully floating requires that the hub be on bearings, while the axle shaft merely attaches to it. It would seem, that if the straightness of the axle housing is of great concern, they must be converting to the non-floating type rear, where the bearings ride on the axle instead of the hub itself. I believe I would prefer to retain the floating configuration.
jollyroger
Jedi Trainee
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Warped rims are of no concern. You are measuring the run out of the axle housing. The wheels don't turn. They stay fixed. You just watch the of the top of the tire as you rotate the housing. Who cares if the wheel is warped. If you were measuring the run out of the hub with a rotating wheel then a warped rim would be a concern.
The sprite has a semi-floater. the side loading is absorbed by a conbination of the bearing, axle flange and the hub. The double bearing unit is also a semi-floater. The difference is you have more than doubled your resistance to side loading at the bearing and vastly reduced the loading of the axle flange /ubbthreads/images/graemlins/yesnod.gif.(which by the way were never designed to take the loading produced by modern sticky tires.)
The real down fall in the single bearing unit is the flex in the bearing. This allows the loading to transfer to the axle flange. After a number of flexing cycles(depending on the loading and the axle) the axle shaft breaks off at the flange. I have seen the flange pull all the way off the end of the axle, leaving the flange still attached to the hub, looking like a kinda flat donut.
A sprite axle is a live axle. A live axle is any solid axle with two driving wheels. It is a live axle regardless of what type of outboard bearing and hub design is on it.
If you can afford a double bearing unit and you are driving your sprite hard it is worth it.
The sprite has a semi-floater. the side loading is absorbed by a conbination of the bearing, axle flange and the hub. The double bearing unit is also a semi-floater. The difference is you have more than doubled your resistance to side loading at the bearing and vastly reduced the loading of the axle flange /ubbthreads/images/graemlins/yesnod.gif.(which by the way were never designed to take the loading produced by modern sticky tires.)
The real down fall in the single bearing unit is the flex in the bearing. This allows the loading to transfer to the axle flange. After a number of flexing cycles(depending on the loading and the axle) the axle shaft breaks off at the flange. I have seen the flange pull all the way off the end of the axle, leaving the flange still attached to the hub, looking like a kinda flat donut.
A sprite axle is a live axle. A live axle is any solid axle with two driving wheels. It is a live axle regardless of what type of outboard bearing and hub design is on it.
If you can afford a double bearing unit and you are driving your sprite hard it is worth it.