rear suspension options?

Discussion in 'Suspension, Steering and Chassis' started by 70dart65coronet, Aug 5, 2018.

  1. 70dart65coronet

    70dart65coronet mopar or nocar

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    What are you guys using to keep your rear end suspension from hopping and moving around.

    i just put bigger rims and tires on.

    I down shifted the other day got a violent reaction from the rear axle, got a enough movement in the leaf spring that the tires touched the body and bend some sheet metal up. luckily it didnt ruin my tires and i dont have a nice paint job yet...:D

    Normally when i down shift at higher RPM to engine brake, the rear tires would skid, well these bigger street slicks dont want to skid or slide.

    ive tried the cheap bolt on traction bars no luck there.

    what are you guys using? does someone make a kit out there? i could only find one on the internet, found a slide a link traction bar on summit racing that fits my application.

    1970 dodge dart with the 8-3/4 rear end. its also has a rubber differential bump stop.

    what do they call it, 4 link? because there is two pivots on each side?

    would it be pretty easy to make something?
     
  2. Locomotion

    Locomotion Well-Known Member

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    I'll bet you have stock type shocks & leaf springs. Shocks aren't controlling the separation and springs may not be stiff enough. I even got wheel-hop when track prep wasn't good with SS springs, but I had the Mopar Performance 4-speed shocks. The proper adjustable Rancho truck shocks solved that problem. 4-link is too much for the street. A Cal-Trac set-up would be the most I'd consider. But they both have a lot of adjustability that you have to figure out. Adjustable front shocks can also help the overall situation as OEM type shocks can be too loose on extension & compression.
     
  3. 72bluNblu

    72bluNblu FABO Gold Member FABO Gold Member

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    What's the plan for the car? Street use only? Street/strip? Daily driver? Corner carver? And how much horsepower are we talking about here?

    There are plenty of leaf spring options out there to take care of what you're talking about, especially if you're still running the stock springs and worn out shocks. But what direction you should go totally depends on how you're going to use the car.
     
  4. 70dart65coronet

    70dart65coronet mopar or nocar

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    Yeah it's pretty much stock setup. And good point about the springs and shocks they could be wore out. The plan is mostly street, occasionally strip. Around 300 hp.
     
  5. jbc426

    jbc426 Well-Known Member

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    Have you considered changing your driving style. I've virtually almost never skidded the rear tires when downshifting, as I roll my heal to the throttle to "blip" the throttle briefly to match engine rev's with the driveline speed.

    Caltracs are way to harsh on the street for me. Did you properly adjust the cheap slapper bars you tried unsuccessfully or just bolt them on as they came? They will not work unless you fit them so that the snubber is just touching the bottom of the front spring eye with half the rubber snubber cut off.
     
  6. loganscuda

    loganscuda DON’T reMember

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    I just replaced my 50 year old leafs with Firm Feel leafs. Took it out for a 2 hour road test on street and winding roads, what a big difference. No more hop or roll. Hugs the corners and hooks up. They are a bit pricey but I like them. I could actually drive the car without the radio on. (To hide all the rattling going on before)
     
  7. 72bluNblu

    72bluNblu FABO Gold Member FABO Gold Member

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    If 300hp is doing that kind of stuff with your spring they're shot. Springs, bushings, shocks, probably all need to be replaced.

    ESPO is a good source for rear leaf springs, you can spend a bunch more for Hotchkis, Firm Feel etc, but if the car is primarily just a street driver a nice set of XHD springs from ESPO should work great.

    The other thing is, you said you just put bigger rims and tires on. How big? What size tires are on there, and do you have the specs for the rims? Because if you went too big with the tires, or missed the proper specs on the rims then even a new set of springs might not help the tire rubbing issues.
     
  8. loganscuda

    loganscuda DON’T reMember

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    ESPO are a lot cheaper and have seen great reviews on FABO. But definitely back them up with good shocks.
     
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    • 70dart65coronet

      70dart65coronet mopar or nocar

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      i went from the stock 5 on 4 215/60R14 to 5 on 4.5 255/60R15 Mickey Thompson E.T Street S/S tires with US Wheel 15x7 with 4.5 back space. I got the bigger axles and green bearings from diff doctor. its the biggest wheel and tire combination i could find that fit the car with out tubing or flaring or shortening axle ect... i have about a inch of clearance from front tire to rear quarter panel.

      espo springs and things website looks pretty good. i think i will try their leaf springs out. what do you think i should go with for rear shocks?

      Recently i replaced the front shocks with the original style from napa. my deep sump oil pan is about 3-1/2" off the ground, and i had to make a bump stop to keep it from getting smashed into the ground when i come off the throttle, these replacement shocks helped, but i think they need to be something more. ill check it out after i get the rear done.

      I had to get rid of the slapper bars because they were in the way of the new tire/rim combo. which might have to do with this whole situation. regardless they had to go due to clearance.

      what is your guys opinion on the rubber differential bump stop...that seems odd to me... with the slapper bars and bump stop i had very little suspension movement before it would hit the bumper... my springs must be spaghetti. i think ill start there...which might help with the front end too.
       
    • 72bluNblu

      72bluNblu FABO Gold Member FABO Gold Member

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      What is the distance from the outside of the tire at the widest point to the inside of the quarter lip?

      255's are pretty much the absolute biggest tire you can fit on a Dart without a spring offset or trimming, and they don't fit without rubbing on every car. Plus the backspace has to be pretty much perfect. The MT ET street tires in 255/60/15 are listed as having a section width of 10.1" , while most '70+ Darts with the stock spring locations only have about 11" from the spring to the edge of the quarter lip, give or take about a 1/4" of body tolerance. So, even if your car is on the upper end of the body tolerance range you pretty much end up with the absolute minimum amount of clearance necessary to keep the tires from rubbing.

      3.5" to the oil pan on a street car is not a recipe for success. I've run my cars at 3.5" from the ground to hard parts before, and on the street (around here at least) it's a royal pain to keep from dragging things with that amount of clearance, even with the significantly stiffer suspension I run on my cars. If you added a bump stop to keep the pan from hitting the ground you're also bottoming your front suspension out, which definitely isn't a good thing especially with the oil pan that low.

      It's beginning to sound like what you need is a full on suspension rebuild, front and rear.
       
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      • 70dart65coronet

        70dart65coronet mopar or nocar

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        yeah i have about 11"-11-1/2" from inside of quarter lip to leaf spring. the tires actually measure about 9-7/8" wide. so im good on side to side clearance. where the tires hit was the front of the quarter panel, which i think was from all the movement in the spaghetti like suspension. I think i should be careful when down shifting in the future, because i dont think those tires aren't meant to skid.

        i got the leaf springs and shocks off. the shocks are shot on the compression side. the springs seem pretty spaghetti like, i can jump on them like a trampoline and they fully compress to the shop floor. plus the rubber bushings are rotten like. probably original to the car.

        so i think this is a good start. i am going to order from EPSO springs n' things. it doesn't look like they sell shocks, i am thinking i might just start with some stock aftermarket shocks and see how those work.

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