Broken rear end. Suggestions on which direction to go.

Discussion in 'Race car chassis tech' started by Briz, Sep 30, 2023.

  1. Briz

    Briz Founders Club Member

    Had an epiphany last night in the shower. For some reason I was thinking the shaft was the same size and there were more or less splines to make for a stronger union. Now I realize its the diameter of the shaft so, no, one cannot put a 40 spline shaft in a 35 spline carrier. Also from what one of my local guys tell me I cannot put a 40 spline spool in a 12 bolt rear. Here is a pic of the R axle. As suspect its snapped. when it let go the power went into the L and snapped the lugs off. Now I have to come up with a plan to make sure this does not happen again.

    ed 384785810_10229169022743888_1570296483521758701_n.jpg
  2. Bens99gtp

    Bens99gtp Well-Known Member

    As I said I was pretty sure there was no way a 40 spline would fit in a 12 bolt. The diameter is so huge is doesn't fit through the carrier bearing.

    The vehicle chattering at the starting line with just eat axles and un joints and all that.

    I would verify all the joints in the suspension are free and not binding as was mentioned make sure the spool isn't damaged.......keep thr shim on each side.........won't really matter if your putting new gears in it it most likely will need some adjustments but will be a close kick off point. Thst twist didn't happen in just a few passes. It take several hits to fully twist one thst far
  3. Jim Weise

    Jim Weise EFI/DIS 482

    I would imagine that setup has been around for a while.. I might suggest that you simply need a new set of 35 spline axles, with drive studs, and your set to get back on the track.

    Axles do have a service life, and I think you will find that the LH axle is not broken, but I bet it's twisted.

    Here's the Axles I would upgrade to:

    If you want bulletproof then here it is:

    I built this rear end for George Sweesy's car, it had 760 ft lbs of torque, multiplied by the high torque stator in one of my 9.5" converters (1.9) and 2.48 low gear of a TH-400. This 3300 lbs car ran consistent 1.20 60 ft's, and I never touched it after the initial build.

  4. Briz

    Briz Founders Club Member

    Actually the L is the first one I pulled cause I had to get a couple of makeshift studs in there to mount the tire and roll it out of the trailer. Surprisingly it was not twisted at all
  5. Bens99gtp

    Bens99gtp Well-Known Member

    Replace them both don't risk it
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  6. Briz

    Briz Founders Club Member

    [​IMG] Rear is out of the car. Notice the bent shock and wheelie bar mounts. Some pretty solid steel. Years of BBB Tq put a hurting on them

    Yep Ben, thats the plan along with a new pro series gear set in the same ratio. all seals and gaskets too
  7. Skyhawk

    Skyhawk Well-Known Member

    That car use to have a 434 brodix aluminum motor with Hilborn injection & ran on alcohol. Ran 178mph top speed. Was a 2 or 3 time champ at Maple Grove. Car has alot of passes on it but was built heavy & strong. Nothing fancy with a Chevette front suspension & Feiro front brakes. We put the rear disc on cause it still had drum brakes in the rear. It was a low buck bracket car.
    Briz and Max Damage like this.
  8. Bens99gtp

    Bens99gtp Well-Known Member

    Sometimes simple is best
  9. Skyhawk

    Skyhawk Well-Known Member

    Worked for me for many years & probably close to 1000 passes while I owned it.
    Guy Parquette likes this.
  10. Guy Parquette

    Guy Parquette Platinum Level Contributor

    Um, was following this thread. But the thought of you in the shower stopped all that. Lol

    ps. I have a narrowed 12 bolt. With full of Strange brand parts, including the center member and axles… never a broken failure
    Tall Deck likes this.
  11. Tall Deck

    Tall Deck Member

    I'm sorry to hear of this, and I'm glad nothing happened at the big end of the track!! I understand that you had an axle failure and obviously you have to address that. But as it's already been suggested by another board member, I think that while you're in there, do it right and get a set of 5/8" diameter wheel studs from either the Mark Williams website or the Strange Engineering website. I'm pretty sure that you're putting some decent power to the pavement with that car, so why not upgrade the small but weak links while you're at it? Just some food for thought. I also like the suggestion to check to make sure nothing in the suspension is binding up.

    Lest you be one of those who might overlook this, let me add that your wheel studs should have non-threaded solid type shanks where they pass through the wheels for optimal strength. So you might have to take some measurements. I wouldn't skimp on this if I were you. You can give the guys at Mark Williams a call if you have questions or doubts.

    51500 - Drive Stud Kit - Mark Williams Enterprises, Inc

    The holes in Most aluminum aftermarket racing wheels fit nice and snug over the unthreaded shanks of these type of wheel studs which eliminates the need for sleeved shank type wheel nuts like you were using, and offers increased strength with the larger stud diameter.

    IMG_5322.JPG IMG_5337.JPG IMG_5338.JPG IMG_5421.JPG OPRS14-2.jpg
    10inchbuick and DaWildcat like this.
  12. Briz

    Briz Founders Club Member

    Thanks for the looking out! As mentioned above I didnt build this just running what came on the car. Its come to light that this current build has been together since the late 80'/ early 90"s. Its seen plenty of abuse over the years and I was lucky enough to be the guy that pushed it past her limits. All the parts listed above have been ordered (strange) and should be here late next week. The heim joints all look fine but there was some binding on the chassis side due to the bolts being over tight and pinching the joint and on the axle side caused by bent shock and wheelie bar mounts. Plan on making some gussets and plating those weak areas. So we'll see how it goes. Should be ready for another try by the end of the month.
    Tall Deck and DaWildcat like this.
  13. Briz

    Briz Founders Club Member

    Got the rear repaired and installed in the car. No damage to the spool. Already has a Pro gear set. New 35 spline Strange axles. 5/8" stud kit. tightened up the lash. was a bit loose. All new seals and it turns nice and smooth. Plated the wheelie bar mounts and reinforced the shock mount. Added new brake pads. All in all Im in it for 1200$. Was expecting twice that at a min. 395044635_845206323809544_6431565292711032485_n.jpg 393290254_842732130648512_3272581569170896314_n.jpg
    tdacton, m louk, 12lives and 2 others like this.
  14. BrianTrick

    BrianTrick Brian Trick

    Your existing 12-bolt can handle it. I have one in a 74 A-body that’s heavy and has gone 8:30’s for a number of years under there. It has 35-spline shafts and 5/8” wheel studs. I have another one in a Monza body like yours that runs 7’s,and it’s been fine. I have found that a Mark Williams shaft is superior to Moser or Strange and there is a reason they are considerably more money.

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