60ft's have always been a struggle in this car, so I put a 2 step it in. Set to a mild 2700 rpm and held with about 70% throttle, I released the clutch and BANG.
While the ring gear sheering all the teeth off is one thing, how the hell do I spin the driveshaft too? The diff destruction should have relieved all the energy. A Denny's 3.5" DS that they said could easily hold 750 hp, but it didn't hold my 370 rwhp.
I suppose it's possible, I'll have to watch the video to analyze a bit. But I do know for sure it broke instantly, and still rolled forward so I could steer it off the racing line.
Maybe time to call Moser for a rear. You don't know on yours after 50 years it may have some issues (some visable and others hidden). Today's aftermarket 12 bolts are beefier and with your stick shift you might want to consider it.
Maybe time to call Moser for a rear. You don't know on yours after 50 years it may have some issues (some visable and others hidden). Today's aftermarket 12 bolts are beefier and with your stick shift you might want to consider it.
That is the plan. The problem is I would like to switch to coil-overs and I don't know if I can get them to fit around my 3" exhaust. Plus I want to mini-tub in the future and thus cant decide if I should go with a narrowed rear end or not.
if this is primarily a drag car put a pro gear in it. they are made with a different alloy designed for higher shock loading but they will wear out driving many miles on the street
i have a built stock 12 bolt in my 900 hp drag car zero problems, we have a 9sec wheels up super stock camaro with a gm 12 bolt zero problems except the gear is changed occasionally due to being a 6.0 gear with a small pinion
i consider myself lucky because i make my own luck. the housing was built by me with 4130 axle tubes and bracing and all mark williams components and a richmond pro gear. i inspect the ring a pinion every year . its a 488 prob go to a 56 when i change engines. the superstock car is harder on rinh and pinions because of the gear ratio. if you are foot breaking a 600 hp street strip car with a 373 gear the ring and pinion should last a ling time
Mine was the stock housing with the tubes welded. 33 Spline Moser Axles with Richmond 4.33 pro gears.
980 HP, 800 Ft lbs of torque. 1.21 60' time off the transbrake. I cracked the teeth on the ring gear after several years but it never broke. I could hear it growling as I coasted into the staging lanes. Still managed to go 1.28 in 60' that day and when I get home found more than 2/3 of the ring gear teeth cracked at the base. Its not the rearend type that is the issue here. Its dead hooking a low numerical gear with tall tires. Its also a radial tire that when it slips chatters like crazy and hammers the gears. A bias ply slick hit as hard as possible with some tire spin will work much better here.
Still have a stock housing in my car with upgrades and have never had a issue in 30yrs had a stick for years and now use a trans brake the car weighs 3800lbs and has been 1.31 in the 60' and is wheels up every launch, so they can work, like anything the right parts and proper maintenance.
The only thing that should have been iffy to me was the stock ring/pinion. I have Tom's 30 spline axles, 1/2" studs, Denny's 3.5" DS, 1350 U-joints, high quality pinion yoke and slip yoke, T56 magnum, RXT clutch, billet flywheel. To me, this should not have blew up like this, but it did.
Aside from beefing it up more, and taking some weight out, is I need add some slip/give on the launch. Either I need to improve my driving and find that slip sweet spot, or I need to perhaps build a bit of a launch control for a controlled amount of slip on the launch. Plus some bias ply DOT slicks would absorb some of the hit as the drag radials hit really hard with a manual trans.
What you are seeing is secondary affect collateral damage from initial failure of the ring gear disintegrating. And that just so happens to be the part you have identified as the one potential weak spot.
After that happened, it threw so much metal around in there that it locked up. With nowhere else to absorb the force, the driveshaft twisted until something else gave (most likely the chewed up pieces from the ring gear getting busted loose again.). Now, there is a chance that that would have happened, but also a chance they fell harmlessly and the pinion would just spin and you see no other collateral damage. It happens.
Once you get one catastrophic failure, there may or may not be follow on collateral damage to other parts which are now subject to stresses from different dimensions and directions they were not designed for. They may or may not handle it.
Heck, you could have blown the carrier caps off when this happened and you didn't (I've seen that happen before too.)
Chris, did this happen in Edmonton on a prepped track? Were your ring/pinion old and perhaps loose with too much backlash.
I used to watch drivers in Edmonton with stick and transbrake cars explode diff's at the starting line when they did not take up the lash in the driveline from the starting line.
those denny driveshafts are pretty pricey... I would suggest a 4" aluminum one out of a 1/2ton chevy and have a driveshaft shop cut it down for you. Generally a cut and balance job around here is $1-150. and the shaft is generally $100. they come with 1350 u-joints in them. This is my current setup, at one point I have a 4.5" in the tunnel when running a auto. It was a tight fight.
rear end I wonder if the lash was loose. There should be much play in the brand new t56. in any even a anything new and built will handle your power out put. 12 bolts have been known to live at much higher power levels with stick cars. Myself I run a S60 with tru trac. I would recommend it. The ear locations are changed to have the 'no hop' bars cast right into the housing.
as for coil overs and custom stuff... after doing a lot of road tripping and what not, I find it is best to stick with stock pickup point and what not. Its just easier to find parts if you break something away from home. Custom is just that when you on the side of the road.
Chris, your car left the starting line and appears to have jacked the tires losing traction. As soon as the car "landed" and caught traction, the carnage ensued. Anti sway bars can do this when improperly set. Axle wind up and they act like ladder bars. If your shocks do not extend, this happens.
Chris, there are several guys here that run hard with these cars. Hopefully. they will chime in and offer up some better suggestions than I could offer.
i broke more than a few parts in the past 3 years : ring gear , plantaries , axle shafts , 3 clutches , m20 transmission.... my lethal combo : slicks + good burnout +2 step+ rxt clutch and vortecpro 585hp engine
i think a good slipping clutch is needed if you are going to be serious drag racing with the stick , the rxt is on off clutch , every time i used the 2 step i broke something
i though Dannys driveshaft are lifetime guaranteed if you twist them ?
i went 4 inch aluminum drag racing shaft aprox 500 usd .... with https://pstds.com
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