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Broken Modern Motorsports billet stub axle


jbc3

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If Ross is watching, is it possible to make a bigger axle with say a 30 spline with a custom companion flange?

I think the problem there is the wheel bearing. You need a larger hole in the strut for a larger bearing. JamieT had made his own strut housings to accept a Z32 stub and bearing assy, and it is a 32 spline but it was not easy. I wouldn't hold your breath waiting for an aftermarket supplier to produce a strut housing that will accommodate a larger wheel bearing and axle.

 

Pics on these threads:

http://forums.hybridz.org/showthread.php?t=100758

http://forums.hybridz.org/showthread.php?t=104649

 

There was another thread if I recall by Jamie specifically about his struts, but I can't find it.

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If Ross is watching, is it possible to make a bigger axle with say a 30 spline with a custom companion flange?

 

Read post #23 in this thread. He's watching!

 

 

Stony is right, these axles were put to the test. My car weighs 3010, I am 200lbs... and there were a bunch of 1.4x launches. Drag racing is very hard on drivetrain parts and without changing the rear, there is probably nothing stronger at this point. My (non scientific...without detailed measured proof) opinion is the shock of the launch is the killer of these axles and those on the road course are not going to see the same fate. If you are truly worried, pull the axles and look at them before your event. My unbroken axle was twisted and it was clear that there was something going on. I would suspect that I had been driving on twisted axles for some time.

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A while back in the earlier days of the NMCA I remember an interview with a guy named David Henninger (I think I got that last name right). He ran an early seventies camaro with an 8.5 inch ten bolt, I assume he had the 28 spline axles running high 8 second times. He made a point to conserve his rearend by keeping away from dry burn outs. I know that kind of take the fun out it, but it was a way to preserve his rear.

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If Ross is watching, is it possible to make a bigger axle with say a 30 spline with a custom companion flange?

 

I think the problem there is the wheel bearing. You need a larger hole in the strut for a larger bearing.

 

Thank you both, I had both of these thoughts last night when I read the last couple of posts in this thread. Now I know I was right about on track.

 

O well, 300whp is more than I will ever drop into a clutch all at once anyhow, I am not a big burnout fan. :)

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Looking at the pics in post 49:

http://forums.hybridz.org/showpost.php?p=787925&postcount=49

It looks like it would be possible to have a larger diameter splined section whilst retaining the stock size bearings. That would of course mean a change in companiion flange to match, and possibly a larger nut to hold it all together, which might then have an impact on what CV axles could be fitted to that companion flange. I'm sure that Ross could come up with a complete set up though for those out there that are harder than hardcode ;)

 

Cheers,

Rob

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Looking at the pics in post 49:

http://forums.hybridz.org/showpost.php?p=787925&postcount=49

It looks like it would be possible to have a larger diameter splined section whilst retaining the stock size bearings. That would of course mean a change in companiion flange to match, and possibly a larger nut to hold it all together, which might then have an impact on what CV axles could be fitted to that companion flange. I'm sure that Ross could come up with a complete set up though for those out there that are harder than hardcode ;)

 

Cheers,

Rob

 

Anything bigger will require different bearings and machinging of teh strut housing.

 

i modded z31 stubs to fit but they broke in the same area!!!

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Looking at the pics in post 49:

http://forums.hybridz.org/showpost.php?p=787925&postcount=49

It looks like it would be possible to have a larger diameter splined section whilst retaining the stock size bearings.

 

Anything bigger will require different bearings and machinging of teh strut housing.

 

Take another look:

new6.jpg

 

I think what Rob is saying (if he isn't, he should be :mrgreen: ) is that the current piece necks down at the

splines - if the OD was kept constant, a 32 spline axle should be possible.

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Larger splines = larger companion flange which = larger bearing to hold the flange. Thats what im saying. if you dont enlarge the bearing the companion flange ( piece that slips over the stub and gets bollted on ) would be extremly thing in that area.

 

 

Someone needs to make an a swap kit that would utilize an r230 with strut housing that would hold the z32 or gtr bearing set and cv axles As refereneced above) . I would buy it.

 

may cost some big bux but it would be worth the hassle of a full backhalve for a solid rearend.

 

my 2 cents.

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LOL Tim, yep that's what I was getting at. Can't say anything about how the larger companion flange will effect the bearing, I've had to scrap everything here so I'm just going on theory and what I can see on the net these days.

 

I've still got my design for a new strut/hub that uses Z32 hubs and brakes, dunno when that will ever happen. Techno Toy Tuning are also working on a similar hub set up, I suspect they'll get to market first ;)

 

Cheers,

Rob

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Hey there Rob, i am back!

 

Hey i am really interested in your comments above about your design/plans for parts for the use of Z32 hubs etc to use the Z32 outer cv. As i also have the Z32 hub/bearing carrier and shafts and outer cv's etc.

 

I had been keeping an eye on Jamie T's fabb'd up rear strut etc, but he is/has sold his car i hear?

 

Could you drop me a line with any info about this as well as the Techno tuning stuff as well.

 

Getting back into my car now, so will be needing to do this soon.

 

Cheers, Clint

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Hi guys,

 

I read this one with much interest. Welcome to the world of heavy duty stub axles. I worked on this with Ross at Modern Motorsports over a year back now after consistently breaking numerous stub axles in my little 4 cylinder S12 gazelle, which while only 2 litres, was running into the 9s at over 147 mph. The S12 gazelle RSX uses OEM R200 CLSD with suspension/crossmember which is identical to Z31 T 300 ZX. What I learned with this car is as follows:

 

1. stock 27 spline Z31 stub axles are good for a few 10 second passes before failure using a manual gearbox. With an auto I expect they'd last a lot longer.

2. make the 27 spline piece out of good material (4340, 300M, 2767 tool steel) and they will get you into the mid nines at 1.4 to 60 ft before they break with a manual box. Expect 8 to 10 passes out of them if you 60 ft into the high 1.30s.

3. the only solution is to increase the axle cross sectional area, which is possible by running a bigger bearing OD on the inner bearing to remove the neck down in the stock Z31 stub.

4. Ross at Modern motorsports has developed these for the Z31 stub axle and it is a 40 spline unit with matching companion flange which fits into Z31s if you use an inner bearing with a 35 mm ID (OD remains 62 mm) and the appropriate oil seal.

5. The part description for the inner bearing is 6007, the new oil seal to suit the companion flange is a 48 mm ID, 62 mm OD, haven't got the part numnber on me at the moment.

 

Ross has manufactured these and I have tested the prototypes and can report they are good to at least 1.33 sec 60 foots and 9.12 &154 mph in my little 4 banger beast. In fact, its possible to hang the wheels in the air a fair ways with these parts. They should get you guys well into the 8's I would think. I attach pics of the pieces- the big stub is on the left. I also attach pics of what they can do for your car.

sml40 spline vs 27_thumb.JPG

wheelsta_thumb.jpg

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PS,

 

There will be nothing metalurgically wrong with the 27 spline MM stubs that broke - they just have limits like all other parts, and the design of the neck down means they will always break at the end of the spline as the spline itself acts as a serration whenever an axle is necked down like that. The part simply breaks at the weakest point and there is nothing you can do about it except either A. cease the brutish launch behaviour or B. go to a stronger part.

 

Personally, I always like to go to the strongest part available..... :wink:

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Radial ball bearings have pretty consistent decription numbers for them as used by manufacturers such as NSK, Nachii etc. A 6007 series bearing has the right dimensions (62 mm OD, 35 mm ID), load and speed ratings to accomodate the part produced by Ross, however if there is enough interest in the part I think he will end up developing and marketing a complete kit including bearing and seal as well as companion flange and of course the stub axle itself. Over to you Ross and Modern Motorsports !

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  • 3 months later...
  • 2 weeks later...

I just snapped my stock 27 spline stubbs again. I am going to have to do something soon as breaking these week in and week out sux. I am leaving on the motor and not even hitting the bottle yet for fear or an explosion back there.

 

I would like to try and get a nine second pass one of these days!

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Well, how much money would people be willing to pay for a set of 40 spin stub axels like pictured above? I could work out the design in solidworks and we could shop it around to machinists as a group. I don't want to get involved as being the inbetween man. I could do the design for the group though.

 

Justin

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