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Thread: Suspension improvements

  1. #1

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    Suspension improvements

    What have you done to the front and rear suspension (IRS) to improve performance/ reduce binding etc that doesn't make the ride noticeably harsher? Spherical bearings??

    I see FFR offers a bump steer kit. Anyone have any experience with this?

    Also, I understand the IRS hub is attached partly solid to the frame and partly with bushings, which doesn't make sense to me. Any downsides to replacing the rubber bushings with solid aluminium bushings?

  2. #2
    Senior Member edwardb's Avatar
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    Factory Five is now offering spherical bearings for the front lower control arms and all rear IRS control arms. http://www.factoryfiveparts.com/1633...-control-arms/. This is an alternative to the mods some have done in the past replacing the poly bushings with heim joints. I don't have any personal experience with either mod. No doubt it does free up the suspension. But Factory Five's own listing says the ride could be stiffer. May not be what you're looking for.

    If you use the Factory Five 2-piece front spindles, bump steer is a non-issue. I haven't actually measured it. But driving two builds with the 2-piece spindles now thousands of miles I've never noticed a bit of bump steer in actual use. Bump steer mods were common with Mustang donor spindles, where it often was an issue.

    Not sure what you mean by the third question. IRS hub? Do you mean the IRS center section? If so, yes it's attached to the frame with four bolts through poly bushings and metal sleeves. It's very tight however. There is little/no discernible movement. I know it's common on Mustangs to replace the factory center section bushings with solid bushings. But this setup is much stiffer from the start. Really no comparison. No reason to change in my opinion.

    General comment/question. Have you actually ridden in or driven one of these? If not, I think you might be surprised. The Mk4 Roadster with all the latest setup parts -- 2-piece front spindles, newer 2015+ Mustang based rear IRS -- rides surprisingly well in stock form. Clearly it's a stiff race inspired suspension. But it's compliant enough that in my opinion is not objectionable at all. I know some guys will change to different weight springs to improve the ride, but I haven't tried that and at least in my experience haven't found necessary. My #8674 build does have the Koni double adjustable shocks. Came as part of the Anniversary package. According to Factory Five, at the softer settings these give a better ride than the stock red Konis. But I think the difference is subtle and they aren't cheap.
    Last edited by edwardb; 05-23-2019 at 05:58 AM.
    Build 1: Mk3 Roadster #5125. Sold 11/08/2014. Build 2: Mk4 Roadster #7750. Sold 04/10/2017. Build Thread
    Build 3: Mk4 Roadster 20th Anniversary #8674. Sold 09/07/2020. Build Thread and Video. Build 4: Gen 3 Type 65 Coupe #59. Gen 3 Coyote. Legal 03/04/2020. Build Thread and Video
    Build 5: 35 Hot Rod Truck #138. LS3 and 4L65E auto. Rcvd 01/05/2021. Legal 04/20/2023. Build Thread. Sold 11/9/2023.

  3. #3

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    Thank you for your insight. So it seems then there is no real benefit for me to do these mods then. I can always look into it again after the car is done anyway.
    I have ordered the double adjustable shocks, happy with that desicion.

  4. #4

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    Quote Originally Posted by edwardb View Post
    Factory Five is now offering spherical bearings for the front lower control arms and all rear IRS control arms. http://www.factoryfiveparts.com/1633...-control-arms/. This is an alternative to the mods some have done in the past replacing the poly bushings with heim joints. I don't have any personal experience with either mod. No doubt it does free up the suspension. But Factory Five's own listing says the ride could be stiffer. May not be what you're looking for.
    Do this. The improvement is amazing. The ride is actually a lot smoother. The rubber and poly bushings tend to bind up. When you hit a bump, it moves the whole car up and down. With the spherical bearings, the suspension actually works and the chassis remains stable.
    .boB "Iron Man"
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    BDR 1642: Coyote, 6 Speed Auto, Edelbrock Supercharger
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  5. #5
    JohnK's Avatar
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    I can't comment on the difference in ride quality or performance with the spherical bearings as I'm a loooooong ways away from driving my car yet, but I did install them in my build. What I will say is that if you're considering them, you want to do them at the time of the initial build. Trying to retrofit them afterward would be a royal PITA.
    MkIV Roadster build: Gen 2 Coyote, IRS, TKO600. Ordered 10/24/18. Delivered 1/29/19. Engine installed 8/8/21. First start 9/12/21. First go-kart 9/17/21. Off to paint 4/11/22. Back from paint 12/30/22. Build thread here.

  6. #6
    Senior Member Avalanche325's Avatar
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    The only change I have done is VPM front and rear sway bars. They definitely helped with autocross / track handling and gives me adjustability. After I got it where I wanted it for autocross, the only change I made is a slight adjustment when I went from Khumos to Nittos. It would be nice to have remotely adjustable shocks. But for the price, it is not something that I would retro-fit.

    Any time you go to solid bushings in pretty much anything, you are going to transfer vibration into the frame, which transfers to the occupants.

    I didn't know that FFR made a spherical bearing kit........there goes a few more $$$$.

  7. #7

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    I may just order the bearings with the kit, and decide later on what i want to do.. Only for the lower front, so 4 there, and for the IRS not really sure, will have to ask FFR

  8. #8
    JohnK's Avatar
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    For the IRS you'll need 4 on each side (x2 for each upper and lower CA) so for the front and rear you'll need a total of 12 bearings.
    MkIV Roadster build: Gen 2 Coyote, IRS, TKO600. Ordered 10/24/18. Delivered 1/29/19. Engine installed 8/8/21. First start 9/12/21. First go-kart 9/17/21. Off to paint 4/11/22. Back from paint 12/30/22. Build thread here.

  9. #9
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    Quote Originally Posted by edwardb View Post
    Factory Five is now offering spherical bearings for the front lower control arms and all rear IRS control arms. http://www.factoryfiveparts.com/1633...-control-arms/. This is an alternative to the mods some have done in the past replacing the poly bushings with heim joints. I don't have any personal experience with either mod. No doubt it does free up the suspension. But Factory Five's own listing says the ride could be stiffer. May not be what you're looking for.
    Will these spherical bearings fit the old IRS (pre-2015)?
    Steve

    FFR #8305; IRS, 347; T5 Trans; EFI, 3.27 Rear; 17x9" Front; 17x10.5" Rear
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  10. #10
    Senior Member edwardb's Avatar
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    Quote Originally Posted by swwebb View Post
    Will these spherical bearings fit the old IRS (pre-2015)?
    I don't know. The Factory Five catalog listing says "These inserts replace the polyurethane bushings in the Factory Five front lower control arms manufactured since January of 2004 and all of the IRS control arms for the 2015 and later Mustang based rear suspension." So I suspect the answer is no. But you should call and ask to find out for sure. They're relatively new, so probably not a lot of actual users out there.
    Build 1: Mk3 Roadster #5125. Sold 11/08/2014. Build 2: Mk4 Roadster #7750. Sold 04/10/2017. Build Thread
    Build 3: Mk4 Roadster 20th Anniversary #8674. Sold 09/07/2020. Build Thread and Video. Build 4: Gen 3 Type 65 Coupe #59. Gen 3 Coyote. Legal 03/04/2020. Build Thread and Video
    Build 5: 35 Hot Rod Truck #138. LS3 and 4L65E auto. Rcvd 01/05/2021. Legal 04/20/2023. Build Thread. Sold 11/9/2023.

  11. #11
    Senior Member CraigS's Avatar
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    I have measured the bumpsteer on the current front suspension. W/ caster at +6.5 deg, the bumpsteer was very, very close to zero. just a point on the 'plastic' bushings. They are a high end plastic. I believe they are from Energy Suspension who list them as being polyurethane. They are now a well designed setup w/ a correct length inner sleeve that actually gets the grease where it needs to go. The sphericals from FFR would be an upgrade in freedom of movement but could be a little harsher. There have been some people who upgraded the front LCAs to rod ends (before the FFR were available) and felt they actually improved the ride. Search for a thread from BillVa for his opinion on that mod that I welded up for him 2-3 yrs ago.
    FFR MkII, 408W, Tremec TKO 500, 2015 IRS, DA QA1s, Forte front bar, APE hardtop.

  12. #12

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    Hmm, maybe the bushing set from Breeze is the answer. They are said to eliminate the binding issue, while still allowing the use of the Poly bushings...

  13. #13
    Senior Member CraigS's Avatar
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    Quote Originally Posted by Oystein View Post
    Hmm, maybe the bushing set from Breeze is the answer. They are said to eliminate the binding issue, while still allowing the use of the Poly bushings...
    I am not sure they are needed. I know that back in the day the inner sleeves that FFR supplied were too short. So the frame mounting ears were closing in on the end of the plastic bushings and adding a lot of friction. As far as I know, that is no longer the case.
    FFR MkII, 408W, Tremec TKO 500, 2015 IRS, DA QA1s, Forte front bar, APE hardtop.

  14. #14
    Senior Member edwardb's Avatar
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    Quote Originally Posted by CraigS View Post
    I am not sure they are needed. I know that back in the day the inner sleeves that FFR supplied were too short. So the frame mounting ears were closing in on the end of the plastic bushings and adding a lot of friction. As far as I know, that is no longer the case.
    X2. Factory Five fixed this some time ago.
    Build 1: Mk3 Roadster #5125. Sold 11/08/2014. Build 2: Mk4 Roadster #7750. Sold 04/10/2017. Build Thread
    Build 3: Mk4 Roadster 20th Anniversary #8674. Sold 09/07/2020. Build Thread and Video. Build 4: Gen 3 Type 65 Coupe #59. Gen 3 Coyote. Legal 03/04/2020. Build Thread and Video
    Build 5: 35 Hot Rod Truck #138. LS3 and 4L65E auto. Rcvd 01/05/2021. Legal 04/20/2023. Build Thread. Sold 11/9/2023.

  15. #15

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    Quote Originally Posted by CraigS View Post
    I am not sure they are needed. I know that back in the day the inner sleeves that FFR supplied were too short. So the frame mounting ears were closing in on the end of the plastic bushings and adding a lot of friction. As far as I know, that is no longer the case.
    Ok, thats exactly what they say at Breeze, that they bind at the ears. Thanks for the info!

  16. #16
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    Anyone going to London that would care to talk about the spherical bearings? I would consider the change for my Challenge Car (IRS) but would like to see something and/or know more about the benefits. Not overly concerned about ride quality.
    Jim

  17. #17
    Senior Member CraigS's Avatar
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    Quote Originally Posted by Jim1855 View Post
    Anyone going to London that would care to talk about the spherical bearings? I would consider the change for my Challenge Car (IRS) but would like to see something and/or know more about the benefits. Not overly concerned about ride quality.
    Jim
    Hi Jim, there is absolutely no question sphericals are the best unless one can use rodends. There used to be a few people who did rodend conversion. I have the jig and did one pair of front LCAs for a friend, BillVa.
    IMG_20160720_105719098 by craig stuard, on Flickr
    IMG_20160722_103826926 by craig stuard, on Flickr
    I have the parts list if you want it and these give options to make them shorter or longer if you want. But I think the FFR sphericals are a heck of a lot easier.
    FFR MkII, 408W, Tremec TKO 500, 2015 IRS, DA QA1s, Forte front bar, APE hardtop.

  18. #18
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    Quote Originally Posted by Jim1855 View Post
    Anyone going to London that would care to talk about the spherical bearings? I would consider the change for my Challenge Car (IRS) but would like to see something and/or know more about the benefits. Not overly concerned about ride quality.
    Jim
    I will be at London, and the sphericals were on my list to get done last winter. The re wiring project took longer than expected and time got away from me, so now it is at the top of the list for next winter. I have all the parts on a shelf, but nothing has been done, so all I can do is talk, nothing to show.
    MK2 #3319.... On the road since 2002 with a lot of upgrades

  19. #19
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    Thanks guys. As usual there's always good info available here; everyone benefits.
    I'll look into the sphericals. Could do rod ends but those can come later if I choose.
    Jim

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