I keep breaking the driver side axle on my turbo 3.4l DOHC. I am using the 282 5-speed equipped with a Torsen. I am up to three so far. The first one was the inner CV. I chalked this one up to the ball cage joint that should have been a tripod. The next two have been broken axle shafts. Both at the splines on the outboard joint. Anyone else have a problem with this? Any ideas on what else to use? Thanks.

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86 GT, 5-Speed
87 GT, 3.4l DOHC Turbo

I broke a couple, but with auto on my v8 car, archie fixed me up. If you using stock axles, where do you get them?

I'm curious... are you breaking them under normal driving conditions, while moving and then getting into the throttle or are you dumping the clutch on it and breaking them on launch?

I am using the 284 axles that came with the Grand Prix GTPs and haven't any issues with mine... so far. I've not run them with the Turbo installed yet.

It's nice to see the tripod joint holding up but the axles? Wow. How much boost total are you running?

I'd be curious to know what you are doing for engine and fuel management.

Are you buying the zxles you are using from the Fiero Store? I had to have my axles lengthend for the wide track suspension I have on my car and had them "Stretched" at a local machine shop that builds axles for dragsters... they'll be plenty strong. I can point you in they're direction if need be.

Very curious...

DKOV -

Roger - They are stock axles but from the parts store. Two from AutoZone and one from NAPA. All have been broken under hard launches. No side stepping the clutch. The axles seem to break a second or two after the launch. I am rebuilding a factory axle and I suspect it is stronger. The parts store axles seem to vary from one to another, so I have very little faith in putting another one in.

DKOV - I am running about 7-8psi of boost right now. It is being fed via a Haltech ECU. I am trying to get the car robust for final dyno tuning. I want to tune the boost level I am running now and increase it as well. I am running pretty conservative on timing and fuel until the dyno tuning is completed. The current setup has run 13.3 @ 103 in the quarter. I figure I have about 275 HP at the crank right now. How are you controlling fuel and spark? Let me know.

Matt

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86 GT, 5-Speed
87 GT, 3.4l DOHC Turbo

You've got to be putting out more than 275 Crank HP... That's only a 50HP gain at 7 psi? That doesn't seem right. At 7 psi you should be seeing closer to 100 additional ponies...

I've been considering the Haltek E6K... Interesting...

In any case, I'm going the route of the stock ECU while cooling the living snot out of the air flow. It's been done before running up to 12 psi on the early 1991 ECU with both an intercooler (with jet cool) and a direct TB spray of 50/50 water/alcohol. I'm not planning on running 12 psi though. I'm thinking about what you are at 7 psi. Maybe 10 if all works out correctly.

I forgot to ask you what year your motors is? My car does not have, nor ask, for MAF input and I wonder if that is why the stock ECU can handle the boost???

Anyway, like everything, it'll be trial and error but I know it can be done as I've seen it done... 12 psi all day long with a stock ECU (arizona open road racing).

In addition, I'm having the motor built specifically for a Turbo application. The heads are being redisigned to handle higher flow and lower heat and are mated to the block via Copper o-rings. The new head design is being port matched to a full upper and lower intake porting. In addition, the exhaust valves are being recut (shelved) and I'll be running about 6 degrees negative. I'm going with 93mm hypo pistons (roughly .040 over), Total Seal rings and SI Valves. My machinist is also taking some weight off the crank and using 327 rods modified to fit the 3.4 TDC crank. The variable we are working on now are the new springs... we are building it to rev to 9500 so springs are the big restraint right now. He is testing for the right set.

Incidentally, if you are wondering, the block sonic's out to .200 at the thickest point so overboaring is totally safe with it. At .040 over, I'm only cutting into it .020 which still gives it TONS of room for "improvement" I figured that would be enought though with a Turbo...

But... think about a 3.8L DOHC NA motor... Torque AND revs! Maybe my next one

You and I should get these cars together! That would be fun!!!

DKOV -

I compared a factory axle to one of the ones I broke and was quite surprised. The factory shaft is almost 1/8" larger in diameter. Also, the tripod is larger. I will post pictures tomorrow of the two, but it is pretty significant. Hopefully the factory piece will hold up better.

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86 GT, 5-Speed
87 GT, 3.4l DOHC Turbo

The ball and cage joints should be stronger than the Fiero's tripots, Im surprized you broke it. You can swap out the hub carriers for Pontiac 6000HD. That will give you stronger hub and axle ends as well as stronger bearings. You will have to drill the hub for the Fiero's 100mm bolt pattern. It's a straight forward swap on a pre-1988 Fiero. The 1988s require a special hub and some machine work to take the 6000 bearings and hub. The 6000 hub is quite a bit stronger and is large enough to redrill to the TransAm/Z-28 bolt pattern, allowing huge brake rotors (with a custom caliper bracket).
I'd check axle lengths, too. It could be that you are either binding due to a too long axle or not getting the axle properly seated due to a too short shaft. Also look at extream axle angles due to lowering.

Check your motor mounts, if they are broke or give too much your axles will bind and break..

Dragon1/Brian

Dragon1 - The mounts are good. After examining the axles, it broke purely due to power. The smaller axles shafts they use for aftermarker rebuilds are too weak to handle the added torque of the engine swap. Hopefully the stock one can.

Matt

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86 GT, 5-Speed
87 GT, 3.4l DOHC Turbo

i never broke axles i broke rear Bearings.. they would sheer off at the out side of the sealed bearing and the hub and then take the axle end with it.. 1slo2m6 and i replaced 3-4 of them on my Nitrous cars... (279hp 312lbft at the rear wheels)

get a hold of Archie.. he's got some connections to make better axles. www.v8archie.com

[This message has been edited by 1FST2M6 (edited 05-07-2003).]

quote Originally posted by peabody: The ball and cage joints should be stronger than the Fiero's tripots, Im surprized you broke it. You can swap out the hub carriers for Pontiac 6000HD. That will give you stronger hub and axle ends as well as stronger bearings. You will have to drill the hub for the Fiero's 100mm bolt pattern. It's a straight forward swap on a pre-1988 Fiero. The 1988s require a special hub and some machine work to take the 6000 bearings and hub. The 6000 hub is quite a bit stronger and is large enough to redrill to the TransAm/Z-28 bolt pattern, allowing huge brake rotors (with a custom caliper bracket).

He didn't break the outer joint. He broke the axle at the outer joint.
Have you ever actually looked at an A-body hub cartridge? Good luck redrilling it and having it hold up.

I dont know the spelling, but Archie uses Mosler (?) axles. Also could try Strange Axles, Ive never known anyone to break one, even in a friends funny car.

I would think that a Mark Williams racing axel might last a while. They make axels for dragsters.

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87GT 3.4 Turbo Best 0-60 5.2 seconds
http://turbofiero.fierojoe.com/turbo.htm

quote Originally posted by Dennis LaGrua: I would think that a Mark Williams racing axel might last a while. They make axels for dragsters.

That's what I'm running, a little pricey at $700 for both splined shafts, but they don't twist or shear (unless a broken CV throws are sharp snap load at them!).

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Click to Listen!

quote Originally posted by Matt Hawkins: Dragon1 - The mounts are good. After examining the axles, it broke purely due to power. The smaller axles shafts they use for aftermarker rebuilds are too weak to handle the added torque of the engine swap. Hopefully the stock one can. Matt

The smaller Dia. Stick axles were actually OEM on some "cheappo" stock Fieros in 84 thru 86. I've seen them on 4 cyl. Fieros that had that little 7.5" clutch & W/O/ A/C etc.

The larger axles you have now are a direct replacement.

DON'T buy aftermarket axles, yuou don't need them...... just use the good stick axles.

Archie