M BODY and 150 MPH

Classic Mopar Racing Forum

  1. BudW

    BudW Moderator Staff Member

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    Smiles. Getting the K-Frame chrome plated (after welding) makes the car go faster . . .


    When you modified your K-frame for big block usage, did you go with flat or with spool type mounts?
    Do you remember what the modifications were exactly?
    I need to do the same to my K-frame (but will keep mine black sense I’m not out to win races).
    Also, it would be best to start a new thread with your answer – as to not highjack this thread.
    BudW
     
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  2. Oldiron440

    Oldiron440 Well-Known Member

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    Bud,
    it's a simple so I'll do it here. I fabbed bracket for the motor and tabs on the K frame that go together with one bolt per side. So no factory mounts and they are solid. I am planing on using a front motor plate and not the K frame. There are so many front motor plates available now plus I have the cage going to the core support. Plans also included solid K frame mount/isolators and a center tie down for winching.
     
    Last edited: Mar 24, 2018
  3. XfbodyX

    XfbodyX Well-Known Member

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    We log nearly 350 passes a year so cracks will happen, even some of the pre abused street driven K-s already have cracks in them.

    Non the less the FF K isnt much more then adding a bit and some welding but they still use oem K-s and the pitfall there is they will crack again in high stress areas just on the side of the new weld no matter what way you weld it.
     
  4. Oldiron440

    Oldiron440 Well-Known Member

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    I worked in a shop that had a contract with the state and repairing Highway patrol cars was always a hoot, little regard was given to preserving the vehicle past the chase at hand. The officer's would tier it up from one end to the other.
    I'd pass on a state car but a county vehicle was a defferan sorry. It's all how there used.
     
  5. M_Body_Coupe

    M_Body_Coupe Well-Known Member

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    As some of the guys pointed out, you want to go over the K-frame really well, find any cracks, repair. Probably a good idea to beef up the various support points, oftentimes people look at:
    1) engine mount cradles
    2) UCA towers (weld in a square brace where the tower is attached to the K-frame)
    3) torsion bar screw mounts

    Otherwise, unless you are looking to make many changes I would just beef up the remainder with either HD OEM stuff or aftermarket (FFI), certainly replace the ISO pucks with poly, alum or steel pieces.

    I re-did the full front end on my coupe, ride is pretty comfortable, it only goes 13@104 mph in 1/4 mile but steady, very smooth - as in glued to the road, not wandering, etc. Yes, I get that is much slower then 150mph, but it is some point of comparison. The fastest I've had that car run was about 120mph, only the windows starting to pop-out were an "issue"....
     
  6. Dr Lebaron

    Dr Lebaron Well-Known Member

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    300 mph, I blow out the windshield.
     
  7. CM360

    CM360 Well-Known Member

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    If I resort to an engine plate, do I relieve the stress on the k frame? I have a universal plate for a SB and BB. I cut a cardboard template of each and was eye balling them last week while the weather was warm for a day.
     
  8. Oldiron440

    Oldiron440 Well-Known Member

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    It also adds rigidity to unitbody.
     
  9. Duke5A

    Duke5A Well-Known Member

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    Seeing as how prone to flexing these things are I would weld the shit out of it if the car is already dissembled. Below is the steering box flexing in my car. Had to weld in a plate on the backside of the steering box mounts to shore things up.

     
  10. Dr Lebaron

    Dr Lebaron Well-Known Member

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    Late 88 and all 89 AHB K frames are the best Mopar made for them.
    70's suck for quality.
     
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  11. XfbodyX

    XfbodyX Well-Known Member

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    The trucks were not much better even with the box bolted to the frame rail, Ive had to re-fab my LRE truck three times in the last 20 years where the box bolts on. It flexed that much like in the vid posted.

    What is a AHB?
     
  12. Dr Lebaron

    Dr Lebaron Well-Known Member

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  13. BudW

    BudW Moderator Staff Member

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    On the fender tag, if an AHB (or A38 for F & older M-body’s) is present - means you have an official police car.
    BudW
     
  14. CM360

    CM360 Well-Known Member

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    From my latest source... the M K's were made in Mexico. In addition to extensive boxing to make the K more ridge, it is only a band aid since the steel is of poor quality. He showed me a pic from his days a Chrysler. Wooden crates marked made in mexico. No dates in the picture.
     
  15. Dr Lebaron

    Dr Lebaron Well-Known Member

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    From 1988 on, the front K-frame was finally beefed up. Previous years tended to bend the upper towers inward, needing constant adjustments to the camber and toe. Eventually shims had to be installed to give more adjustment, as none was left.
     
  16. Duke5A

    Duke5A Well-Known Member

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    I've been having severe issues with my alignment. Every year the toe is really out of spec and I have wear on the outsides of the tires. Camber seems to be OK though as I installed shims to give enough adjustment. I can't keep the damn toe in spec though. Taking it for its yearly alignment soon and I'll have another printout to compare to last year's specs. Does these things ever stop sagging?
     
  17. BudW

    BudW Moderator Staff Member

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    It sounds more like a Camber problem, than it does toe-in, to me.
    When you have tire wear on inside or outside of tire - Camber is the reason.
    Toe-in (or toe-out) will cause a feathering of the tire blocks where tire is scooted sideways down the road. A test for a toe-in/out problem is to run your hand on top of tire in a few directions (don’t do this if you have cords poking through the rubber!). If the tire blocks have high ridges on one corner – the you (also have) a toe problem. If nothing jumps out on the hand test – then toe is where it should be.

    This is an exaggerated picture of what I mean, indicating toe wear:
    Tire Feather Edge A.png
    Top is normal, middle is feathered edges from toe-in being off and bottom is camber tire wear.

    You can have both camber and toe-in issues – but camber is what causes tires to wear on inside (or on outside).
    BudW
     
  18. dvw

    dvw New Member

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    The stock suspension is overkill for drag racing. Good bushings and no worn hard parts. We have 3 stock front suspension cars. 76 Volare, 123mph, 62 Savoy, 142mph, and 64 Belvedere, 150mph. All drive great. As you can see the 64 has plenty of "landings".
    Doug

    FB_IMG_1467732999733.jpg
     
  19. LSM360

    LSM360 Well-Known Member

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    ^ What Dr Lebaron has written, plus my '89 AHB with aluminum k frame isolators handles so well at high speeds with the rubber isolators gone.