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  1. #1
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    Mar 2018
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    Default 68 Firebird rear suspension help... Recs needed, bang for buck corner carver

    Posting this for my brother..... Looking for rear suspension recommendations.


    My brother is about re-start on his 68 Firebird that’s been sitting for 10++ years. Car is currently bare bones stock. He has a 400 he built that can rev a little (or he may go LS) and a Keisler 5 speed he wants to use. Will need a new rear end. Probably won’t mini-tub it. 4 link or torque arm (or other options???), pros/cons? Lives in the Santa Cruz mountains, wants it to be a corner carver.


    Any recs for a decently priced rear end set up that’ll make this thing really handle/ride well?


    Thanks!

  2. #2
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    Sep 2005
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    Depends on what you call "Decently Priced"

    BMR SUSPENSION





    813-986-9302 Phone
    813-986-8055 Fax
    tc@bmrsuspension.com
    www.BMRSuspension.com
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  3. #3
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    May 2014
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    Stanislaus County Ca.
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    My 68 Camaro was fun at the autocross and did plenty well on back roads just lowered 3" with ridetech shocks, Hotchkis leaf springs, frame connectors,solid body mounts, some RE-71R tires and a good alignment.

    I just recently mini tubbed it and went to a torque arm set up.

  4. #4
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    Apr 2009
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    Michigan
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    Quote Originally Posted by ilikeike View Post
    My 68 Camaro was fun at the autocross and did plenty well on back roads just lowered 3" with ridetech shocks, Hotchkis leaf springs, frame connectors,solid body mounts, some RE-71R tires and a good alignment.

    I just recently mini tubbed it and went to a torque arm set up.

    Out of curiosity, how much of a difference did switching to the torque arm make? Better handling? Better ride? Less axle hop? More predictable handling?

    A lot of people see noticeable improvements when going from stock leaves to a torque arm or 4-link, but I'm curious how much difference there is between a well set up leaf car (like you had) to a torque arm or 4 link setup.
    - Ryan

  5. #5
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    Mar 2018
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    Default

    I realize there is no simple answer to this shotgun blast question and he’s going to need to do a deeper dive....

    BMR.... After checking out your recent detailed post and looking into it, your torque arm seems like a good, budget minded upgrade. A few questions... with just the Torque Arm, do I get noticeably more straight line traction than lift bars/CalTracs? (obviously the ride quality would improve). Will just the Torque arm noticeably improve handling?

    Are the benefits between the torque arm and the torque arm/watts link/control arm set up you offer noticeable in a street driven car with street tires?

    Thank you.

  6. #6
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    May 2014
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    Stanislaus County Ca.
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    Stab 6902:

    I'm putting about 500hp to the wheels, I was having serious axle wrap issues. The third member actually broke off the pinion snubber once, had to modify that, then bent the Hotchkis sway bar cross member after I moved the snubber to the cross bar,Doh!
    it handled pretty well, but I was over powering the Hotchkis leaf setup pretty badly. It would have been fine for back roads or auto-X with a little less HP/TQ maybe, especially if you just wanted to stay on a smaller budget.

    With the torque arm and one autocross race this year so far, the car definitely tracks better since the rear isn't twisting and moving like it was. feels much more controllable coming out of corners with my foot in it. I also went from a 275 to 315 tire at the same time,so that helped.

  7. #7
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    Apr 2009
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    Michigan
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    Quote Originally Posted by ilikeike View Post
    Stab 6902:

    I'm putting about 500hp to the wheels, I was having serious axle wrap issues. The third member actually broke off the pinion snubber once, had to modify that, then bent the Hotchkis sway bar cross member after I moved the snubber to the cross bar,Doh!
    it handled pretty well, but I was over powering the Hotchkis leaf setup pretty badly. It would have been fine for back roads or auto-X with a little less HP/TQ maybe, especially if you just wanted to stay on a smaller budget.

    With the torque arm and one autocross race this year so far, the car definitely tracks better since the rear isn't twisting and moving like it was. feels much more controllable coming out of corners with my foot in it. I also went from a 275 to 315 tire at the same time,so that helped.
    Thank you very much for the real world feedback! This is just the sort of info people need to make a smart decision based on how their car is setup and their specific needs.
    - Ryan

  8. #8
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    Dec 2014
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    Jasper, Indiana
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    While a torque arm is a great design, you'll benefit more from a 4-link system. If you're wanting a corner carver that doesn't beat you to death when driving around town, 4-link is the way to go. Not only will you have better ride quality on the street (compared to a torque arm suspension), you'll also save some money. With the ridetech bolt on 4-link and matching adjustable coilovers, you'd be out the door ready to go for around $2200.
    Jody Glenn
    Ridetech Sales Specialist
    812-481-4751
    jglenn@ridetech.com
    https://www.ridetech.com/

  9. #9
    Join Date
    Nov 2016
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    Sulphur, La
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    Jody,
    As a guy that has had both I am going to have to ask for some data to back up that statement.

  10. #10
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    Sep 2005
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    Quote Originally Posted by NovaSF View Post
    I realize there is no simple answer to this shotgun blast question and he’s going to need to do a deeper dive....

    BMR.... After checking out your recent detailed post and looking into it, your torque arm seems like a good, budget minded upgrade. A few questions... with just the Torque Arm, do I get noticeably more straight line traction than lift bars/CalTracs? (obviously the ride quality would improve). Will just the Torque arm noticeably improve handling?

    Are the benefits between the torque arm and the torque arm/watts link/control arm set up you offer noticeable in a street driven car with street tires?

    Thank you.
    Yes, the Torque Arm eliminates Axle Wrap which you are trying to control with the CalTracs. With the Combo of the Torque Arm & the Watts Links the Suspension articulates perfectly. So Handling & Straight Line are vastly improved


    BMR SUSPENSION





    813-986-9302 Phone
    813-986-8055 Fax
    tc@bmrsuspension.com
    www.BMRSuspension.com
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  11. #11
    Join Date
    Nov 2016
    Location
    Sulphur, La
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    390

    Default

    For a bolt-on kit that is pretty sexy

  12. #12
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    Dec 2014
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    Jasper, Indiana
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    The reason for the ride quality difference is that most off the shelf torque arm kits run a high spring rate causing a stiffer ride - this makes it better suited for a dedicated race car without modifying the kit. It all comes down to wheel rate and shock travel. We run a 5.2" stroke shock which allows us to lessen the spring rate allowing for better control which then turns into a smoother ride. Now, I'm not saying a decent ride can't be obtained from a Torque Arm suspension kit (because it can), you may just have to spend some extra time figuring everything up.
    Jody Glenn
    Ridetech Sales Specialist
    812-481-4751
    jglenn@ridetech.com
    https://www.ridetech.com/

  13. #13
    Join Date
    Nov 2016
    Location
    Sulphur, La
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    I would love to have a technical discussion on this since we have a vendor for each in the thread if you guys are game on sharing specs.
    Assume using the OP's 68
    What roll center (rear) is achievable on each kit typically?
    What wheel rate is typical without using a swaybar? (Not spring rate)
    What wheel travel in each direction is typical? (not shock travel)

    Typically I would say that a TA car could get away with slightly lower spring rates then a 4-link car and have the same wheel rate as long as the roll center is the same. I chose a 4-link for my 69 but have had 3-links and TA's before. They all can work great if setup properly. They all have drawbacks as well. I have never heard the argument of ride quality being better on a 4-link over a TA so it could be a fun discussion.

  14. #14
    Join Date
    Oct 2005
    Location
    Jasper,IN
    Posts
    539

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    I am not really into getting into a huge debate on 4 link vs 3 link vs torque arm. They all have their pro's and con's, and when designed properly....they all work well.
    Back to answering some of your questions. The roll center on the ridetech 4 link system is around 11", this could vary somewhat depending on the exact ride height. Anti-Squat is around 70%, there is some adjustment on the lower bar axle bracket. Through extensive R&D and racing we have found these numbers to work very well.

    Taking the shock angle, shock position and the axle rotation into consideration the wheel rate will be about 13% higher than the spring rate. The standard spring rate we use is 200, so the wheel rate would about 225lbs. If racing the car we would recommend around a 275 or 300. (310-340)

    We use our 5.2" stroke shock on the majority of our 4 link systems, with a .4" thick compression stop. The shock angle technically increases that travel, but is offset by the axle rotation (upper bars are shorter than the lower bars). Wheel travel is right at 5".

  15. #15
    Join Date
    Oct 2005
    Location
    Jasper,IN
    Posts
    539

    Default

    Quote Originally Posted by NovaSF View Post
    [FONT="][FONT="]Posting this for my brother..... Looking for rear suspension recommendations. [/FONT][/FONT]
    [FONT="][FONT="][/FONT]
    [/FONT]

    [FONT="][FONT="]My brother is about re-start on his 68 Firebird that’s been sitting for 10++ years. Car is currently bare bones stock. He has a 400 he built that can rev a little (or he may go LS) and a Keisler 5 speed he wants to use. Will need a new rear end. Probably won’t mini-tub it. 4 link or torque arm (or other options???), pros/cons? Lives in the Santa Cruz mountains, wants it to be a corner carver. [/FONT][/FONT]
    [FONT="][FONT="][/FONT]
    [/FONT]

    [FONT="][FONT="]Any recs for a decently priced rear end set up that’ll make this thing really handle/ride well?[/FONT][/FONT]
    [FONT="][FONT="][/FONT]
    [/FONT]

    [FONT="]Thanks![/FONT]
    The ridetech coilover system is well proven performance suspension system that works well on the street or at the race track. Here is a link to that system. Also, Currie and GearFX now offer 9" Rearend with our brackets already welded on to make the install even easier.
    https://www.ridetech.com/products/su...ilover-system/


    Depending on his budget the StreetGrip is another great alternative.
    https://www.ridetech.com/application...etgrip-system/

  16. #16
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    Mar 2018
    Posts
    41

    Default

    Really good info here. Thanks everyone!

  17. #17
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    Apr 2009
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    Michigan
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    Thank you for your detailed information Darren. It's clear you guys have done your homework and put together a well thought-out system. I think the 5" travel shocks are an important piece of the equation for ride quality, especially for a street car running lower spring rates.

    As a point of reference for those interested, the stock shocks have 8" of travel.
    - Ryan

  18. #18
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    Nov 2016
    Location
    Sulphur, La
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    390

    Default

    BMR or another TA company want to share specs?

  19. #19
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    Jan 2003
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    Arizona
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    Quote Originally Posted by stab6902 View Post
    Out of curiosity, how much of a difference did switching to the torque arm make? Better handling? Better ride? Less axle hop? More predictable handling?

    A lot of people see noticeable improvements when going from stock leaves to a torque arm or 4-link, but I'm curious how much difference there is between a well set up leaf car (like you had) to a torque arm or 4 link setup.
    I switched from leafs to a torque arm many years ago and the difference was night and day with respect to ride quality handling and traction. That's because leaf springs must serve to functions -- hold up the vehicle and locate the axle. Leaf springs can never work as well as link suspension where the support/locating functions work independently.

    More recently, I switched to ridetech HQ coilovers from another brand and ride handling improved even more -- mostly ride quality. Comfortable, but tight and responsive -- especially in quick transitions.

    There are a lot of really good bolt-on link-type suspension options available.
    ________________
    Steve Chryssos


    Ridetech.com
    Email: stevenATridetech.com

    My PT Garage:
    https://www.pro-touring.com/dto_show...preview&g=1288

  20. #20
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    Feb 2018
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    Southern IN
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    I can tell you I used to run Southside Machine lift bars with 3" lowered mono leaf springs, rear sway bar, bolt-in subframe connectors and 275/50-17 BFG Drag Radials. I then switched to Cal-Trac bars with the same setup and now I run DSE's Quadralink with their 1" sway bar. The lift bars did great for straight line performance but really impacted ride quality. The Cal-Tracs were a huge improvement in ride quality and still did well with straight line and cornering but in both cases the rear suspension was, no doubt, in a constant bind with not much room for movement. The car actually cornered pretty well but nowadays, there's no comparison on ride quality or cornering. It's hard to narrow things down as I completely updated the suspension, steering and brakes but there's definitely no comparison between the two systems. I don't regret the change in the slightest and I'd do it again in a heartbeat.

    Shane
    #theanchorholds
    Link to my build thread:
    http://lateral-g.net/forums/showthread.php?t=56387


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