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Need some opinions to prevent this from happening in the future. Took 96 C4 LT4 6sp to the track last night and broke a half shaft and it was pretty violent when I hit 2nd gear and almost lost the drivers side rear wheel in the process. I have a 388 stroker probably putting down at least 400hp to the rear with a 4:10 rear and had new u-joints all the way around so I guess the weakest point was the end of the half shaft. It has been fine on the street because it has a hard time getting traction but a very sticky track is another story. My plan is to get 1350 HD half shafts and new Timken wheel bearings and possibly rear wheel bearing axles, wheel studs depending on the damage. Any other recommendations? Once back together might just skip the track in the future.
I’m looking to avoid this happening as we have similar power but I haven’t hit a track... from my research Denny’s NITROUS half shafts are damn near unbeatable I think they have a warranty to if you break they will replace them for free don’t quote me though.. I’m going to buy them soon they are around $800 for a set
This was my damage after breaking a halfshaft. After a couple of halfshafts, bunch of spider gears, and a spindle, I went with a 12 bolt. If you are thinking of serious 1/4 mile duty, go with a straight axle.
Yeah I’m scared of that but although I want low 1/4 ET I’m building it for cornering/open road racing Mexico etc. So I’m trying to beef up the IRS. I’m going Denny’s nitrous half shafts and driveline, summers bros inner/outter stub axles heard they are like 2k but un breakable 🤷🏻♂️ Then most likely upgrade to the hammerhead D44. They say they have build with 1000hp and yet to have problems.. then when the trans can’t take it I’ll give bill (zfdoc) a call 😂 but I’m stubborn and don’t want to swap out the rear to a solid. I’ll be happy with a mid to low 11 and I’ll be at HP700/TQ670 so I’m trying to see what come up with... we’re you running half shaft safety loops when this happened? I’m going to buy the driveline/half shafts saftey loops soon. I just put the c-beam plates on but yet to drive the car
Yeah I’m scared of that but although I want low 1/4 ET I’m building it for cornering/open road racing Mexico etc. So I’m trying to beef up the IRS. I’m going Denny’s nitrous half shafts and driveline, summers bros inner/outter stub axles heard they are like 2k but un breakable 🤷🏻♂️ Then most likely upgrade to the hammerhead D44. They say they have build with 1000hp and yet to have problems.. then when the trans can’t take it I’ll give bill (zfdoc) a call 😂 but I’m stubborn and don’t want to swap out the rear to a solid. I’ll be happy with a mid to low 11 and I’ll be at HP700/TQ670 so I’m trying to see what come up with... we’re you running half shaft safety loops when this happened? I’m going to buy the driveline/half shafts saftey loops soon. I just put the c-beam plates on but yet to drive the car
I heard the roads in Mexico are really nice this time of year!
Travis (383tpimachine) installed a hammerhead rear end in his 85. He had a build thread called "the quest for power"
More than likely one of the U-Joints broke and the half shaft thrashing around beat itself to death. The factory aluminum half shaft are pretty strong. Stronger than the U-Joint and the outer stub axels in my experience.....
U- Joint wise only use the Spicer PN 5-1350x in the half shafts and PN 5-1310x in the Driveshaft.
Also clutch in a 6spd plays a huge part in how long things live on the drag strip ysing stock C4 IRS .... twin disk or puck style clutches just beat the crap out of the rear end. Nothing will stay together very long using thise type clutches. I have been 10s in my NA 92 6spd using a Spec 2+..... I have also busted everything from the driveshaft back using a MCleod Street Twin and Spec Stage 3 in that same car. I have also been mid 8s@155mph in my 84 with a TH350 swap on the stock D44 IRS with a spool..... I built the 84 to prove to people how to make the D44 IRS live and how fast someone could go on it. And I don't mean a single hero pass.... I went that fast week after week for 2yrs documenting every pass and how long the parts lasted (U-Joints crushedthe neede bearings out after 50-75 passes, outer stubs about1 season).... Yes I converted the 84 to a 9" Ford rear and Powerglude a few years ago, currently running only 1/8th mile but equivalent to high 7s or very low 8s in the 1/4(4.90s to 5.20s depending), but only after I exceeded every goal I ever had for the car on stock IRS.
Something else that matters is the rear spring and shocks.... you need to keep the rear from squatting down. The half shafts control the camber in the C4 suspension..... All that side load at the hit on the half shafts kills stuff. You need a z51 rear spring , good D/A shocks ( I recommend Viking) and extended bump stops.
Will
Last edited by rklessdriver; 11-26-2019 at 04:37 PM.
More than likely one of the U-Joints broke and the half shaft thrashing around beat itself to death. The factory aluminum half shaft are pretty strong. Stronger than the U-Joint and the outer stub axels in my experience.....
U- Joint wise only use the Spicer PN 5-1350x in the half shafts and PN 5-1310x in the Driveshaft.
Also clutch in a 6spd plays a huge part in how long things live on the drag strip ysing stock C4 IRS .... twin disk or puck style clutches just beat the crap out of the rear end. Nothing will stay together very long using thise type clutches. I have been 10s in my NA 92 6spd using a Spec 2+..... I have also busted everything from the driveshaft back using a MCleod Street Twin and Spec Stage 3 in that same car. I have also been mid 8s@155mph in my 84 with a TH350 swap on the stock D44 IRS with a spool..... I built the 84 to prove to people how to make the D44 IRS live and how fast someone could go on it. And I don't mean a single hero pass.... I went that fast week after week for 2yrs documenting every pass and how long the parts lasted (U-Joints crushedthe neede bearings out after 50-75 passes, outer stubs about1 season).... Yes I converted the 84 to a 9" Ford rear and Powerglude a few years ago, currently running only 1/8th mile but equivalent to high 7s or very low 8s in the 1/4(4.90s to 5.20s depending), but only after I exceeded every goal I ever had for the car on stock IRS.
Something else that matters is the rear spring and shocks.... you need to keep the rear from squatting down. The half shafts control the camber in the C4 suspension..... All that side load at the hit on the half shafts kills stuff. You need a z51 rear spring , good D/A shocks ( I recommend Viking) and extended bump stops.
Will
what flywheel wheel did you use and was the spec 2 the best clutch in your experience and what was your TQ rating and gears at the time? Sorry if I ask a lot of questions just want to learn from you rather then the hard way lol and what was your best luck with inner and outter stub axles
what flywheel wheel did you use and was the spec 2 the best clutch in your experience and what was your TQ rating and gears at the time? Sorry if I ask a lot of questions just want to learn from you rather then the hard way lol and what was your best luck with inner and outter stub axles
I used both a Fidanza aluminum flywheel and a Spec regular weight steel flywheel. The steel flywheel was easier to launch consistently with traction at the track but there was no ET difference when I was able to launch both right. I did like the aluminium flywheel on the street better. The Spec 2 clutch was very nice.... I often regretted selling it. I ended up putting 2 different Spec 3 clutchs in the car (one before the Street Twin and bought a new Spec 3 after) and it just broke rear end stuff all the time with those clutches..... I bought new parts to change it back to a Spec 2 with a steel flywheel but I never got around to it before selling the car. I put the clutch in a customer cars and sold the flywheel along with my first Spec 3 to a member here with the disclaimer about what to expect if he ever hooks it up at the track...
My 92 made around 500RWHP and just over 400RWTQ.... I won't give specifics or the dyno sheets because the current owner is a member here and while I don't think he hustles the car in Mexico (like I did) - its no longer my info to give.
I ran both a 3.90 and 4.10 rear gear in the car. The 4.10 was faster.
Outer stubs on the 92 broke all the time.... the later cars (after 89) have longer outer stubs.... thats how GM widened the track width on the suspension. I had half a dozen right rear outers that were broken on display in the shop for years before I threw them in the scrap bin. Sucks because more often than not it takes the wheel bearing out too... Anyway I could break them at will on good track prep.... Just by coming out on the clutch too hard.
I learned alot with the 84. Because it was an early car with the shorter stronger outer stubs and had the automatic transmission..... they lasted way longer and the car went way faster. Running a stiff wall bias ply slick tire helped as well as I only ran 315 17 Drag Radials on the 92 and dead hooking a radial tire is rough on axels.
Will
You may want to put some safety loops on the driveshafts as well.
Totally ...in a vette youre sitting right on top of it. Any performance app should have them.
Agree wtih a straight axle. The difference unless youre a road course rat is minimal. Cant beat a good 12 bolt 9 in etc.
I used both a Fidanza aluminum flywheel and a Spec regular weight steel flywheel. The steel flywheel was easier to launch consistently with traction at the track but there was no ET difference when I was able to launch both right. I did like the aluminium flywheel on the street better. The Spec 2 clutch was very nice.... I often regretted selling it. I ended up putting 2 different Spec 3 clutchs in the car (one before the Street Twin and bought a new Spec 3 after) and it just broke rear end stuff all the time with those clutches..... I bought new parts to change it back to a Spec 2 with a steel flywheel but I never got around to it before selling the car. I put the clutch in a customer cars and sold the flywheel along with my first Spec 3 to a member here with the disclaimer about what to expect if he ever hooks it up at the track...
My 92 made around 500RWHP and just over 400RWTQ.... I won't give specifics or the dyno sheets because the current owner is a member here and while I don't think he hustles the car in Mexico (like I did) - its no longer my info to give.
I ran both a 3.90 and 4.10 rear gear in the car. The 4.10 was faster.
Outer stubs on the 92 broke all the time.... the later cars (after 89) have longer outer stubs.... thats how GM widened the track width on the suspension. I had half a dozen right rear outers that were broken on display in the shop for years before I threw them in the scrap bin. Sucks because more often than not it takes the wheel bearing out too... Anyway I could break them at will on good track prep.... Just by coming out on the clutch too hard.
I learned alot with the 84. Because it was an early car with the shorter stronger outer stubs and had the automatic transmission..... they lasted way longer and the car went way faster. Running a stiff wall bias ply slick tire helped as well as I only ran 315 17 Drag Radials on the 92 and dead hooking a radial tire is rough on axels.
Will
Are there stronger stub axles available?
I'm rebuilding the suspension in my 85 right now, and while I'm in there... I might as well do those also.
Thanks for the tip on the Spicers, btw. I ordered the same part you listed, but the coated version.
I'm rebuilding the suspension in my 85 right now, and while I'm in there... I might as well do those also.
Thanks for the tip on the Spicers, btw. I ordered the same part you listed, but the coated version.
Summers Brothers will modify the stock outer stub axels by cutting the splined stub off, broaching a hole in the remaining Yoke and pressing in a bigger splined stub, then welding on the backside. Then they will broach the wheel bearing to fit the bigger stub and respline the drive hub.
I think youd be wasting money trying to upgrade. The early 85 stub axels are quite a bit shorter and stronger than the later cars. I only broke 1 in my 84 and it was orginal to the car, had a couple yrs of racing on it plus 100k stock miles.... I went faster than anyone ever imagined on all stock 84 half shafts and stub axels. Best 1.26 60ft and like I said eventually I ran mid 8s at 150+ on that stuff.... only hurting U-Joints periodically.
The costs and custom fabrication needed to upgrade the IRS to go faster than I was going is why I just straight axel swapped my 84. Cheaper and same level of fabrication.
Will
Last edited by rklessdriver; 11-28-2019 at 07:53 PM.
Summers Brothers will modify the stock outer stub axels by cutting the splined stub off, broaching a hole in the remaining Yoke and pressing in a bigger splined stub, then welding on the backside. Then they will broach the wheel bearing to fit the bigger stub and respline the drive hub.
I think youd be wasting money trying to upgrade. The early 85 stub axels are quite a bit shorter and stronger than the later cars. I only broke 1 in my 84 and it was orginal to the car, had a couple yrs of racing on it plus 100k stock miles.... I went faster than anyone ever imagined on all stock 84 half shafts and stub axels. Best 1.26 60ft and like I said eventually I ran mid 8s at 150+ on that stuff.... only hurting U-Joints periodically.
The costs and custom fabrication needed to upgrade the IRS to go faster than I was going is why I just straight axel swapped my 84. Cheaper and same level of fabrication.
Will
10-12-2019, 08:03 AM
Drag Race Distruction Upgrades Needed
