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Anyone else running Griggs Racing suspension with Torque arm?

Discussion in 'SVT Shelby GT500' started by builttodrive, Mar 17, 2020.

  1. builttodrive

    builttodrive Member Established Member

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    I am running the Griggs Racing suspension with torque arm and Watts link that the previous owner had on my 07 GT500. I am also running a Drive Shaft Shop one piece aluminum drive shaft and I get a little vibrating coming in at higher speeds. like 100 mph+. Just wondering if there is any pinion angle adjusting that needs to be done or what other things it could be. The car had a DSS two piece shaft on it when I got it and It sat so low I couldn't get into my driveway and after raising my coil overs up a bit the two piece shaft was too short so I decided to upgrade to the one piece.
     
  2. HKusp

    HKusp Active Member Established Member

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    What tires are you running?
     
  3. builttodrive

    builttodrive Member Established Member

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    American muscle wheels with Michelin Pilot Super Sport tires. Things are pretty smooth until I get to around 100 or faster and then I pick up a pretty good vibration.

     
  4. SteveWK

    SteveWK Active Member Established Member

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    I know there has been a lot of discussion about the MPSS death wobble on this site. That may be your problem or maybe something is out of balance. I have a Griggs torque arm and watts link and really like them. The torque arm fixes the pinion angle relative to the differential. The only way to adjust it is to shim the torque arm with washers between the bolts where it attaches to the differential. This will rotate the differential up or down relative to the drive shaft. I would do the following:

    1) Check the pinion angle to see if it is within spec
    2) Search for MPSS death wobble or Michelin wobble on this forum and the 13-14 GT5000 form to read up on that well documented problem. The death wobble only occurs at high speed.
    3) Make sure tires are balanced well
    4) I suppose there could be a problem with the drive shaft, but I'm not an expert in that area. Something to think about though.
     
  5. Black Cobra '99

    Black Cobra '99 Active Member Established Member

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    Its unlikely to be the pinion angle because if the angle is way off then you'll have vibrations at all speeds, and it its a little off you'll have vibration under load.
    Since its at a constant speed, its because something is out of balance, tires, wheels or driveshaft.
     
  6. HKusp

    HKusp Active Member Established Member

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    That is why I asked. As Steve pointed out, there is a well documented issue with those tires at high speed. I would start there.
     
  7. builttodrive

    builttodrive Member Established Member

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    Thanks for the input everyone. I was scratching my head a little because whenever I have had a vibration on a car in the past weather it was wheels/tires, drive shaft, or pinion angle everything has showed up at much slower speeds. If it was good around 70-80mph it was good at 100+ too. In some of my reading with the Michelins it seemed like a lot of people were saying a specific size was an issue. I have 295/35-19 in the rear and I think the 295 was a size they spoke about a lot. Just makes me wonder if my fronts in a 265 are ok and also if the problem still exists. I can burn the rears off pretty fast and wouldn't mind going a little wider in the rear but not sure what I want to put on the car. These Michelins hook really well and the fronts have a lot of life left and the rears are pretty good yet too.
     
  8. HKusp

    HKusp Active Member Established Member

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    Mickey Thompson Street Strips are DOT approved and hook really well if you get the pressure right and don't mind the TPMS sensor message on the dash. you could move up to a 305 or 325 in your size.

    ET Street® S/S
     
  9. SCGallo2

    SCGallo2 Balanced performance Premium Member Established Member

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    I have MPSS 295/35ZR19 (104Y) Extra Load tires (originally spec'd for BMW) on the back and haven't had any issues with them. With a little heat in the tires, they hook pretty well. I am aware of the death wobble threads in the 2013-14 section, running 20" wheels.
     
  10. builttodrive

    builttodrive Member Established Member

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    I believe mine are extra loads as well. The other option wasn't spec'd heavy enough for the shelby so Costco could only sell me those. Well it looks like I really need to find another set of wheels and tires to try and rule things out and help determine whats really going on.
     
  11. ante

    ante Member Established Member

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    I have a saleen watts link for years and had to go back to a two piece drive shaft. Some guys are lucky with the pinion angle if the car is not too low. But if you are sig lowered you cant adjust it enough with the watts. Binds.
    Tried two different one piece drive shafts. Would vibrate between 55-65, nothing over or under.
     
  12. tomshep

    tomshep Another R Addict Established Member

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    I had 295/35/20 MPSS and the death wobble on a 11" rim. I believe they were the K1 tires. It wasn't a high speed wobble. But when I accelerated under full throttle it would come in at around 90 as I recall and the car would start whipping left and right rapidly from the rear. You couldn't drive it and had to lift.

    Tom
     
  13. builttodrive

    builttodrive Member Established Member

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    I'm waiting for the weather to turn around here a little bit and be able to get back out and road test it but from memory my vibrations doesn't sound like the death wobble. I don't have any side to side stuff its just like somethings out of balance but only at higher speeds. I probably need to make some various tests to better diagnose. I don't typically reach those speeds slowly so it's generally under hard acceleration and I don't typically exceed the 100 mph range much especially because of the vibration. It would be nice to get it figured out so that I can run it at the track at those speeds and greater without worrying about a vibration shaking me to death.
     
  14. darkside323

    darkside323 Member Established Member

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    Hi!!! I have a full Griggs Rear Suspension with everything being Rod Ended. So yeah my NVH went way up. I'm cool with it though. Couple of questions.

    Have you checked your front wheel bearings?
    Have you checked if everything is tightened down in your front suspension?
    Have you tried reclocking your driveshaft?

    Asking because I've had that come up in the past as a cause of vibration at different speeds.
     
  15. Catmonkey

    Catmonkey I Void Warranties! Premium Member Established Member

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    I attempted to run the Grigg's coil-overs in the rear, but I had issues with my wider tire choices, so I had to get rid of them. Doesn't help your issue, but you'll need to check what clearance you have before bolting on larger tires.
     
  16. BelminZ

    BelminZ Member Established Member

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    Hello!

    I am in search of a low mile mint condition 13-14 white w/blue stripe Shelby gt500. Needs to have every option including recaros and glass roof. Please feel free to text/call me at 513-338-9761 if interested in selling!
     
  17. builttodrive

    builttodrive Member Established Member

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    My car was set up with some different brackets from Griggs and It allows me to run 315's. I have 295's on it now with tons of clearance. I think my problem is my wheels though.
     
  18. builttodrive

    builttodrive Member Established Member

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    I decided to take my wheels and tires into Costco today to have them check balance. When I picked them up they said the two rear wheels were bent and took a lot of weight to balance. I'm disappointed but not real surprised. When I bought the wheels new from American Muscle one of the fronts was rejected for being bent. American Muscle was very good about it and sent me out a replacement front asap of course no charge. I do remember the installer saying they took a lot of weight to balance and he said the Michelin tires I had put on generally balance really well and don't require much weight. I'm going to reach out to American Muscle to see if anything can be done but it looks like thats most likely the issue.
     
    Last edited: Mar 30, 2020 at 6:51 AM
  19. me32

    me32 BEASTLY SHELBY GT500 TVS Moderator

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    Merged threads as it was part of the same thread
     
  20. Catmonkey

    Catmonkey I Void Warranties! Premium Member Established Member

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    I used those brackets and it didn't help. Grigg's spec'd wheels have a lot less offset (+45mm) than it takes to keep the tire inside the wheel well. But they also rely on shorter diameter tires/wheels too. It's a bit more track oriented than what I need.
     

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