It might be time to try a modified inner CV like Mike and I talked about it the meeting last winter.......
It might be time to try a modified inner CV like Mike and I talked about it the meeting last winter.......
Yep, gun drilling the ends is part of the conversation with DSS...
I'm somewhat thrilled that the new temper on the ends lasted thru 9 launches including 3 on a VERY sticky track
JT
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Not sure if you have seen the inner cv on the set that Eric Depenbrok had made. That thing is a beast. The guy told him" I want to shake your hand if you break these". I'll see if I can get him to post a pic.
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That sucks JT.
I can check when I get home but I'm pretty sure the SRT4 has the same diff spline as the 568. Please enlighten me on this gun drilling idea.
I dont know the size, but i know they are larger.In my last conversation with DSS they recommended a larger spline diameter for the Diff end. Anyone know the spline size (diameter) of SRT-4 axles compares to our axles? I figure the quick 5-speed SRT-4's are heavier and making more power, just curious how those axles stack up?
SRT/t850 > 'big spline/normal' K-car > 1g neon
Intriguing, eh? Makes you wonder if a 568 ring gear will bolt to a t850 diff carrier... Because if so it might be 'simple' (in building a drivetrain for a 10-second FWD car terms..) to put together a setup with SRT-splined inners.
Dont push the red button.You hear me?
Is the axle spline size the reason why we haven't been able to use the SRT4 Quaife?
I've got a T850 and set of axles at home I'll measure up tonight. You're right, they do look larger in the picture. I can pull the 850 Quaiffe and compare it to the 568 as well.
^ Excellent! If the ring gear can be made to go onto the t850 diff carrier, the carrier itself is almost guaranteed to be workable in a 568 case.
Dont push the red button.You hear me?
The SRT-4 axles are definitely larger diam. and will Not go into a 568. (tried it years ago) I want to say that we also looked into the possibility of swapping the SRT-4 diff section/ring gear and concluded that it did not look promising. Not positive though, so Hopefully something can work out of this, as the 04-05 Stock SRT-4 axles are tough. Dozens of runs on 26" slicks in a Full bodied (no CF) low 11 second car cutting low 1.7X 60's and Zero breakage.
Robert Mclellan
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10.04 @ 143.28mph (144.82 highest mph)
Worlds fastest 8v MTX Shelby Charger
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The 2nd, less desirable option would be trying to swap the open-diff t850 side gears into a k-car diff carrier, or machining the stock diff carrier and re-splining the stock side gears to accept the srt axle. But, that wouldn't get you a limited slip diff unless you did the same work to an obx or quiafe.
Dont push the red button.You hear me?
Yes, I saw those when you guys came to the Mopar Nats last year, definitely looked beefy! I forgot if I got a pic or not, if Eric can get one that would be great. If he got them from DSS, I would like to reference them!
Drilling out the core of the axle rod to make it a tube... theory is to remove the high stress material at the middle of the section. Got free time to FEA/fatigue simulate this?
Awesome, let me know what you find!
Good info, keep it coming guys!
JT
SDAC Director
SDAC-Chicago President
JOIN SDAC and your local Chapter TODAY! - SUPPORT the CLUB that supports YOUR HOBBY!
87 Shelby Z - 10.50@141.66mph
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Ask for a rainbow and you shall receive a rainbow.
I did a quick solid vs. hollow study and it kind of concluded what I thought. It has been my understanding that drilling a shaft could be done for the purpose of weight and inertia. The peak stresses in a shaft which is in torsion are at the outer skin with a non linear decline to the center. Since the stresses at the center of a hollow shaft are small this material can be removed with little effect on the peak stresses. Therefore you get a shaft which is "just as strong" with less weight and rotational inertia.
I took a 1.5"x12" solid shaft and applied a 500 ftlb torque to the end of it while fixing the opposite end in all directions. I did the same thing but the shaft had a .5" hole down the center. The peak stress in the shaft only changed by 0.36% and the weight was reduced by 11.1%. What was interesting, and this may just be a simulation anomaly, is that the solid shaft wanted to deflect laterally with the torque where the hollow shaft only deflected radially. In the pictures below the deformation is displayed over 100 times greater then real life but you can see how the solid shaft dips at the bottom and the hollow stayed concentric. If this actually happens then there would be added stress if the end of the solid shaft was constrained from moving in this direction.
I couldn't do a fatigue test since I didn't have an S-N curve but the results should be near the same between the two pieces since the peak stresses were so close. The stress distribution pictured also shows why case hardening becomes an ideal solution. It will increase the yield strength of the outer surface where the highest stresses are while leaving the center in a weaker yet more ductile state where the strength isn't needed.
From this I don't see how gun drilling will help the problem at hand but it could be done to lighten the part with very small consequences in the area of strength.
DJ
What we were thinking about the whole gun drilling idea is that whats happening is the axles are twisting off at the splines. So you take a solid shaft and the twist starts at the center. You take a drilled shaft and now the ID is technically larger and I thought it would be harder to "twist" a hollow shaft with a larger ID that not. Does that make any sense? We would drill it say a 1/4" past the splines and then run a ball end mill in it to get rid of any steps from the bit so there are no stress risers. We also wanted to take a ball end mill and take out the steps at the end of the splines so there is less of a stress riser there as well. Thoughts.........
I will post some pics up tomorrow. I'm sure frank from dss will copy them for you Jt. Maybe we should put mine in your car as a test. I'm pretty confident they won't break!
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JT, did you extend the pivot arm 1.5" like I showed in the pics I sent you? If not, you will have a very small window of engagement and the clutch will be like a switch, very hard to slip. If you did, then you Should have enough of a window to slip it, just a matter of getting the feel for where that window is.
Robert Mclellan
http://www.youtube.com/watch?v=wambNdfnu5M
10.04 @ 143.28mph (144.82 highest mph)
Worlds fastest 8v MTX Shelby Charger
Manitoba's Fastest 4cyl!
8 valve, No Nitrous!
New clutch combo is the SH!T!
Jackson, I see where you're coming from but the fracture will always start and the point of highest stress. As you can see in my quick FEA the outer "shell" of a smooth shaft will have the highest stress. Put a stress riser out there like a spline and you have your point of initial yielding. Shortly after yield will come material failure in the form of a stress fracture which effectively decreases the major OD. Now you have the same torque force and a smaller diameter so the stress becomes greater again. Since there was already enough stress to fail the material it just keeps going until the whole shaft fails. Usually in the fracture you will see a smooth break at the outside where the stress crack started and then it will go to a rougher twisted look where the material failed very quickly all at once as the stress through the whole piece becomes greater and greater. The center of a solid shaft will actually have the least stress in the whole system which is why you can get rid of it with out greatly effecting the strength of the part. Hopefully that makes sense.
I measured the axles last night and the SRT4 came in at ~1.16" on the OD of the splines and the TD axle was 1.08". That gives ~15% more cross sectional area. So not huge but still substantial enough to make a difference. I didn't measure the minor diameter of the splines but I'm sure the gains are close to the same and this was just to get a feel of the size difference.
Now to use the SRT4 spline you would need to either do a bunch of work to the TD diff or use the SRT4 diff. You also need to increase the diff bearings as the shaft inside of the splines is also larger. There is room to fit the SRT4 diff bearings in but the 568 carriers would need to be machined out to match the larger OD.
So onto the diff. I pulled the Quaife from the T850 and compared it to the OBX out of my A568. Side by side they are almost the same height with the Quaife being slightly smaller. Not a real big deal as this could be taken up in bearing shims. I put a level across the top as a quick gauge and it was close. My bench was sloped the other direction by about the same amount so you could say it was about a half degree off level.
When I took the ring gear off you can see the mounting face is a decent amount higher on the OBX. With the Quaife the gear is actually mounted on the opposite side so the SRT4 gear position is way off.
Luckily the bore and bolt patter of the 850 vs 568 ring gear is the same so for fun I tried mounting the 568 gear upside down on the top of the Quaife mounting flange. This actually got the gear pretty close to where it needs to be. A small spacer and locater adapter would need to be made as that side of the Quaife wasn't intended to locate a gear but I think it could work. I was starting to get excited so I dropped it in my 568 case and all my hopes were shattered. Because the mounting flange is so thick and offset more to the center it interferes with the case. Then you put the ring gear bolts in and it interferes even more. You make be able to clearance the case and close up the hole you make but I'm not sure how this would effect the strength in that area and my suspicions are it would make it weaker.
Now I do think it could still work but it would take quite a bit of machining. Regardless of the route taken you need to machine the bearing housings to fit the larger Quaife diff bearings. I don't think that would be too difficult and it is very possible. The only way I see getting the T850 diff to work is to reverse engineer the top section of the Quaife and build it with a flange that matches A568 diff. This isn't a really complicated piece but now you need to pick materials and heat treatment using your best judgement or get the current piece tested for surface hardness and material properties to try and match the original. With out a 3D scanner it will also be fun to precisely locate all the internal bores and mounting holes. Once again, it is very possible but you are starting to look at some serious $$$. A chunk of 4340 or 8620 that size will be rather pricey just to begin with. Then the engineering, machining and heat treating and it wouldn't surprise me if you have a $1000-1500 part by the end. It makes you wonder if it wouldn't be better to just build up a T850 and replace the A568.
^^^^This was the same conclusion we came to, IF the 568 becomes a weak point, time to upgrade to the T850.
BTW, nice write-up! Couldn't remember (seems like a long time ago) why we scrapped this idea, just remember looking into it and coming to the same conclusion. Your write-up brought it all back
Robert Mclellan
http://www.youtube.com/watch?v=wambNdfnu5M
10.04 @ 143.28mph (144.82 highest mph)
Worlds fastest 8v MTX Shelby Charger
Manitoba's Fastest 4cyl!
8 valve, No Nitrous!
New clutch combo is the SH!T!
Thanks Eric, pics would be a great help for my conversation with Frank! Really curious what is different as I'm afraid the current combo can break any axle
I think preloading would help
I didn't have to extend it with the standard ACT clutch but when I put the twin disk in I was afraid of overextending the spring so did extend it, forgot how far though, was just enough at the time. friction point on this clutch is very minimal, but I think the part that kills axles is how quick it grabs from slip to grip
Thanks, that helps...
Thanks for the detailed info man!
To look at it another way, do you think there is enough meat in the OBX to bore it out for SRT-4 axles and keep the same bearings? The splined inner OBX parts could be EDM'd out to receive the larger shafts.
JT
SDAC Director
SDAC-Chicago President
JOIN SDAC and your local Chapter TODAY! - SUPPORT the CLUB that supports YOUR HOBBY!
87 Shelby Z - 10.50@141.66mph
87 CSX #751 Clone - 12.88@102.88mph
www.badassperformance.com
Check out Turbo-Mopar Times!
Submit your 1/4 mile times HERE!!
Support SDAC! Join Today!
"I'm not some pro athlete with a bajillion dollars, I'm just an every man"
Note: The information and any images provided in this post are not for distribution outside this forum without the author's permission.
Thanks DJ. That was a heck of a post.