Wheel Hop, and Dampers

[Senna1]

Hi,

New-ish member here, with a '13 Brembo GT starting off all stock. Car is my daily driver, commuting 50 mi. a day round trip over mixed surfaces, so I've been hesitant to move away from stock, especially on ride height. And for the first 35k mi, I just enjoyed owning a V8 pony car (and the Mustang I've always wanted).

That said, I have a couple concerns now that the car isn't brand new anymore:

1.) Wheel hop. I can't launch this car hard, at all; anything above 3k rpm and the axle starts tramping and doesn't stop until I lift. It's been like this since I bought it (on the stock summer P Zero tires, and a replacement set of the same). I suspect the tires have something to do with this, but as I'm on a new set in the rear (long story) I'm going to have to deal with that factor as best I can till they're worn out.

Are LCAs likely to help reduce the axle tramp? I've read some past threads (and Vorshlag's epic 2011 build) and the consensus is... well, there isn't one. Whiteline has a good rep with many, but they're basically a poly/poly design and others advocate for more articulation. Honestly, I'm afraid of rod-ends and sphericals on a DD. But, I'm intrigued by the del-sphere/roto-joint design on the axle side that some offer (UMI; others?).

2.) Damping. The car has poor body control, which is no surprise to anyone who's driven one. I know opinion here is 'divided' between Koni & Bilstein shocks/struts, but regardless of brand I assume there's agreement that replacing the stock dampers is worthwhile, even when staying on OE (non-lowering) springs? Is there any opinion on some of the other strut/shock combos out there like Steeda Pro Action and Eibach Pro Dampers? Not sure I want to go with adjustables, but if I did the only options in my budget would be Koni Sports or FRPP (D-Specs, from what I gather).

Again, the goal is just to fix a couple foibles with the car as my fun daily driver. I may eventually get to a track day/HPDE or the occasional autoX, but I'm not building towards that end, or concerned about class rules (famous last words...).

 

[noldevin]

I too had terrible wheel hop on my stock '14 track package. I can't say which mod helped the most as I did my suspension pretty much all together along with new tires and wheels, but my hop is 100% gone after doing BMR LCAs, UCA and mount, relocation brackets, BMR handling springs, and Koni Yellows.

I will say that I think I've outgrown the useful range of the Konis with my setup. With my RE11's I have to crank the fronts way up to reduce steering lag and body roll which creates a rather uncomfortable ride (and I'm sure they'll blow sooner or later).

 

[Norm Peterson]

The modification path I generally recommend is to do one thing at a time until the hop either goes away entirely or drops below the point where it happens often enough to be a bother. LCAs (because they're easier to get at), then UCA (if necessary), then LCA relocation brackets. They can all be done independently of each other with little duplication of work.

I'm running Currie's rear LCAs, which are a poly/spherical-but-not-rod-end kind of LCA, and up until a month or so ago was still on the OE springs with Koni yellows (BMR's GT500 handling springs are on it now, but no track time yet). Car is still good as a DD, and it's seen 15 or so track days as described. The car is composed enough to gather unsolicited comments to that effect at those track days. Suspension is one area where road course mods work out better for a DD than the more common dragstrip-oriented mods do.

About the only 'negative' with the Konis seems to be if you over-lower the car or run it around with enough heavy stuff in the trunk or back seat to cause the rear suspension to bottom out badly enough.

I have not ridden in a D-spec equipped car, but my experience with Tokico's Illumina line (which might be what the D-specs evolved from) is that they ride pretty harshly over short, sharp bumps like railroad tracks.


Norm

 

[Senna1]

I too had terrible wheel hop on my stock '14 track package. I can't say which mod helped the most as I did my suspension pretty much all together along with new tires and wheels, but my hop is 100% gone after doing BMR LCAs, UCA and mount, relocation brackets, BMR handling springs, and Koni Yellows.

I'm hoping to avoid doing a complete makeover, to be honest. The LCAs are easy to get to and have big rubber bushings, so I was hoping they'll be a/the solution all on their own... maybe over optimistically.

I'm running Currie's rear LCAs, which are a poly/spherical-but-not-rod-end kind of LCA, and up until a month or so ago was still on the OE springs with Koni yellows (BMR's GT500 handling springs are on it now, but no track time yet). Car is still good as a DD, and it's seen 15 or so track days as described. The car is composed enough to gather unsolicited comments to that effect at those track days. Suspension is one area where road course mods work out better for a DD than the more common dragstrip-oriented mods do.

I take it you had few complaints with that setup (LCAs & Konis @ OE ride height) then? I'm curious how much the hybrid poly/spherical LCAs increase NVH. Looks like a few vendors offer something in that vein.

About the only 'negative' with the Konis seems to be if you over-lower the car or run it around with enough heavy stuff in the trunk or back seat to cause the rear suspension to bottom out badly enough.

I plan on very little to no lowering; I was considering swapping my OE Brembo springs to the OE Boss 302 ones (~15% stiffer, maybe .75/.5" drop F/R) along with a damper upgrade, but opinions on Boss springs on the GT seem to be pretty mixed since they run different tire setups and maintain the stiffer rear spring bias of the GT.

FRPP P springs are also on the table potentially, but from my reading they're even softer than the OE Brembo rates, and I'm not sure that lower AND softer is the way I want to go.

Until I decide, will probably just do dampers and see how that works out.

I know what I should do is take all my mod money and go to Summit Point instead...

 

[oldVOR]

I put LCA's on my '14 GT Track Pack and it reduced wheel hop but did not get rid of it. I added an UCA and the combination of the LCA's and UCA got rid of the wheel hop all together.

My son's car has a Bilstein setup with K springs, CC plates, adjustable sway bars, LCA's, relo's, adjustable panhard bar and it handles better than my '14 with stock dampers.

Being in DC Metro myself (NOVA), you're more than welcome to take a look at the setup.

 

[mrgtx]

Mine was 85% cured with a Steeda UCA. I held off on doing the LCAs since our Brembo/Track Pack cars supposedly come with somewhat better pieces than the base GT/V6 cars do (Sourced from the GT500??)...and I thought that would make sense as a second thing to try.

The rest of the wheelhop was eliminated when I did shocks and springs...still on the stock LCAs.

 

[Whiskey11]

The modification path I generally recommend is to do one thing at a time until the hop either goes away entirely or drops below the point where it happens often enough to be a bother. LCAs (because they're easier to get at), then UCA (if necessary), then LCA relocation brackets. They can all be done independently of each other with little duplication of work.

I'm running Currie's rear LCAs, which are a poly/spherical-but-not-rod-end kind of LCA, and up until a month or so ago was still on the OE springs with Koni yellows (BMR's GT500 handling springs are on it now, but no track time yet). Car is still good as a DD, and it's seen 15 or so track days as described. The car is composed enough to gather unsolicited comments to that effect at those track days. Suspension is one area where road course mods work out better for a DD than the more common dragstrip-oriented mods do.

About the only 'negative' with the Konis seems to be if you over-lower the car or run it around with enough heavy stuff in the trunk or back seat to cause the rear suspension to bottom out badly enough.

I have not ridden in a D-spec equipped car, but my experience with Tokico's Illumina line (which might be what the D-specs evolved from) is that they ride pretty harshly over short, sharp bumps like railroad tracks.


Norm

I'll throw in my two sense on D-Specs.... AWFUL... simply awful. They rode like complete ass even with the stock springs and the valving was absolutely horrible. When I wanted more rebound I had too much compression... when compression was right I didn't have enough rebound. I don't know why companies make dampers that do this.

I went from D-Specs with Steeda Sport springs to Ground Control coilovers, initially with 440/200 springs then to 550/275 springs and the GC's rode better even at those spring rates than the D-specs did with the stock springs that I banished them to damping... Just goes to show that good dampers go a long way.

As for the wheel hop, the vast majority of the wheel hop is actually from the UCA. If you look at the UCA's bushing there are huge voids in the front and back (top view, side view) of the bushing:

That's where your wheel hop is coming from. As you step on the gas the whole axle housing rotates top rearward front inward and that bushing gets stressed like a spring. If your tires ever lose grip for even a second it will start oscillating back and forth like an undamped spring.

Now LCA's will help tremendously by minimizing the bottom of the axle tucking in, but the UCA is really what is responsible for handling the axle wrap up. Problem is, replacing the UCA is a PITA and generally comes with a corresponding increase in NVH. LCA's... not as much.



That was my rear suspension on my 2009. Not a peep from the rear suspension except for the occasional squeak of a poly bushing being in need of some grease every couple of months. Very minor increase in gear whine with the car but nothing that could be heard over the exhaust or radio.

 

[BMR Tech 2]

If wheel hop is your only concern, then I would recommend starting with just the LCAs. In my experience, they eliminate a majority of the wheel hop. If you're happy with the wheel hop reduction from a set of LCAs, then no need to go further with a UCA/mount/relocation brackets/etc...

Poly/bearing LCAs will add a small bit more noise than traditional poly/poly LCAs, but it shouldn't be too bad.

 

[Norm Peterson]

I take it you had few complaints with that setup (LCAs & Konis @ OE ride height) then? I'm curious how much the hybrid poly/spherical LCAs increase NVH. Looks like a few vendors offer something in that vein.

Very few. In street driving with the Konis set only a little bit above full soft, no complaints at all in street driving. On the track at something like +1.5/+1.25 turns above full soft, no shock complaints or even anything specifically about too much roll. Just too much nose dive under braking, and I think the car could do better if it took a set just a bit quicker.

The LCAs have been absolutely quiet and don't seem to have transmitted any additional noise or harshness. I do notice a little "stiction" and barely-above-subliminal vibration if I haven't lubed them in a while. Even then, it's mostly noticed by the difference going from the "before" directly to the "after".


Just as an FYI, BMR's GT500 handling springs ended up lowering the front of my GT by barely half an inch, which I would have preferred even if the GT500 springs weren't any stiffer than their GT springs (they're about 20 lb/in stiffer at both ends). The rear went down about an inch initially, and I've shimmed about half of that away. 1" down is just too low for me either aesthetically or for functional reasons (including the Koni's apparent poor tolerance for much lowering).


Norm

 

[Norm Peterson]

As for the wheel hop, the vast majority of the wheel hop is actually from the UCA. If you look at the UCA's bushing there are huge voids in the front and back (top view, side view) of the bushing:

That's where your wheel hop is coming from. As you step on the gas the whole axle housing rotates top rearward front inward and that bushing gets stressed like a spring. If your tires ever lose grip for even a second it will start oscillating back and forth like an undamped spring.

I'm kind of curious as to what the middle of the UCA bushings look like. These bushings have to accommodate UCA rotations about vertical axes through the bushing bolts as the body moves laterally (due to roll) relative to the axle. It's a tough problem to solve, offering minimal rotational stiffness against one of the moments while offering high translational stiffness against the principal loading axial to the UCA.

The best you can hope for is that you can take the worst disadvantage out of one kind of loading without hurting the other too badly in the process. OE's attempt to do this with voided bushings. I've done voided poly (for LCAs on a different car), and the voids (similar to your bushing picture) can make a very noticeable difference in articulation and the induced roll stiffness that comes when you don't have enough of that.

That the S197's UCAs are so short only aggravates the issue - greater angularity at any given amount of roll (plan view) is the result.

I just looked at my old LCAs, and the bushing at one end is also voided. But in this case the voiding is at the top and bottom rather than ahead of and behind the inner sleeve.


Norm

 

[Tri-bar]

I would go with the Ford Racing Boss 302R arms, I use them for the street and do very well.
http://www.americanmuscle.com/frpp-boss302r-lca-0514.html

At the Track I like the Boss 302S arms and I have on most of the time.
http://www.americanmuscle.com/frpp-boss302s-lca-0512.html

For the upper arm I like the Hotchkis
http://www.americanmuscle.com/hotchkis-upper-controlarm-1113.html

I don't use Anti squat brackets, but most seem to like them.

Use whatever arms you like, This setup works for my car very well, that's all I can tell ya. I just like simple and I tend to stick with the Ford stuff.
Wish they made a upper arm, The Multimatic arm is very pricey. Just my $.02

 

[Senna1]

I put LCA's on my '14 GT Track Pack and it reduced wheel hop but did not get rid of it...
Being in DC Metro myself (NOVA), you're more than welcome to take a look at the setup.

Thanks for the offer! I very well may take you up on it before I make a purchase. I see a lot of Mustangs in the area, but have talked to very few owners. Hit up the occasional C&C (Bethesda usually), but a basically stock GT doesn't do much for the crowd there, understandably.

I'll throw in my two sense on D-Specs.... AWFUL... simply awful. They rode like complete ass even with the stock springs and the valving was absolutely horrible. When I wanted more rebound I had too much compression... when compression was right I didn't have enough rebound. I don't know why companies make dampers that do this.

I went from D-Specs with Steeda Sport springs to Ground Control coilovers, initially with 440/200 springs then to 550/275 springs and the GC's rode better even at those spring rates than the D-specs did with the stock springs that I banished them to damping... Just goes to show that good dampers go a long way.

D-Specs have a good reputation in the last community I was in too (Subaru), but I didn't care for them in that application. Very harsh. I've heard similar comments about the FRPP handling pack dampers, which are also Tokico-sourced. No comment on their quality, I just don't think they offer the ride I'm seeking, though I can't claim hands-on experience with the FRPP stuff.

Problem is, replacing the UCA is a PITA and generally comes with a corresponding increase in NVH. LCA's... not as much.

Thanks for those pics. I'd read that the UCA is the true problem, but that really clarifies why - there's nothing there in the front to back plane. I'm hesitant to do much about it though, for the reasons you've already stated.

Poly/bearing LCAs will add a small bit more noise than traditional poly/poly LCAs, but it shouldn't be too bad.

I see you guys offer a couple version of poly/bearing LCAs too; what's the realistic service life of the bearing in a DD situation? Are we talking a 'grease them every few months' type deal, or 'tearing down and replace the bearing every 10k miles'?

Looks like I have some more to think about that just rushing out and buying the 'go-to' parts...

 

[BMR Tech 2]

I don't recommend greasing the bearings. The grease will trap dirt and grit, forcing it into the bearing and chewing the teflon up. You can purchase rod end boots that go over the rod ends to help keep garbage out. Do you drive the car in the winter?

 

[Boaisy]

LCA's will help with the wheel hop. If you plan on going towards HPDE/AutoX, I'd go with BMR's Poly/Rod combo LCA's with their black elastomer bushings. Kelly sent me some of those, and he said they are more oriented for the lateral loads where as their "normal" bushings are focused at drag racing. Pretty much, if you get the "normal" bushings, after quite a few HPDE/AutoX's, they will end up like this:



For the few months that I was able to run the Poly/Rod LCA's with the elastomer bushings, they worked really well. That combined with the shocks/springs below, the car was a dream to drive on the course. I also had the relocation brackets with the LCA's as well. NVH didn't increase that much, at least for me. However, I bought the car with poly/poly LCA's already on it.

For Shocks/Springs, I had the Vorshlag StreetPro kit (Eibach Pro springs) with their camber plates, and it was a good kit for DD/Track days. It handled like a beast around the corners. There are better options, but it would be a nice stepping stone before going to full blown coil overs (good ones are $3k+). Takes about 2 hours to install at home, and you don't even need a spring compressor.

http://www.vorshlag.com/product_info.php?cPath=141_142_179&products_id=559

For UCA, I had the Whiteline V2 UCA. I would say it probably didn't make too much of a difference vs. the stock one. However, there better designs out there. I never really played around with the UCA options that much to find an improvement. I was looking at getting the UMI UCA, but never purchased it before losing the car. I've heard changing the bushing on the differential housing helps as well.

 

[Sky Render]

I've got the "extreme" full spherical UCA from BMR. Amazing handling with no wheel hop, but the NVH is... extreme, shall we say?

Sent from my Samsung Galaxy Note 4 using Tapatalk

 

[oldVOR]

I've got the "extreme" full spherical UCA from BMR. Amazing handling with no wheel hop, but the NVH is... extreme, shall we say?

Sent from my Samsung Galaxy Note 4 using Tapatalk

Vince, have you tried dynamat on the entire area under the rear seat?
It helps to knock down a great deal of the transmitted noise being amplified by the sheet-metal floor pan.

 

[Senna1]

Forgot to ask in my last post:

Just as an FYI, BMR's GT500 handling springs ended up lowering the front of my GT by barely half an inch, which I would have preferred even if the GT500 springs weren't any stiffer than their GT springs (they're about 20 lb/in stiffer at both ends). The rear went down about an inch initially, and I've shimmed about half of that away.

These are the GT500 SP072 Springs (260/220 F/R lbs/in)? Did BMR advise you they'd give less than advertised drop on a GT, or was that just lucky? Wonder if the same holds true of all their GT500 springs fitted on a GT (SP070 in particular)

I gather shimming the rear springs isn't particularly difficult... something like a weight jacker I assume?

 

[Norm Peterson]

Yes, that's the part number. I was advised to expect less than the advertised amount of drop, which was fine with me, because from the get-go I really didn't want to lower my car much more than 5/8", maybe 3/4" tops. Keep in mind Koni yellows and 25.9" tall tires here . . .

I was already figuring that the combination of less weight up front with a little more spring rate than the "regular GT" handling springs would at least reduce the amount of drop from the 1.5" advertised. And if I was a bit lucky I might not have to shim the front at all. Before shimming, the rear dropped just over an inch, close enough to what I was expecting.

For shimming, I just started with some strips of 3/8" and 1/8" steel and broke out the acetylene rig, MIG-welder, a hacksaw, and a few other implements of destruction/construction and just rolled my own. What I ended up with works, but I think I'm going to revise the manner of locating the spring and probably at least tack the shims in place. They don't move, but I sometimes get a little noise when backing up over a bump. I don't want to post pictures of a work in progress.


Norm

 

[Speedboosted]

You should look in the OEM springs from a 2013/14 GT500 with the performance pack. They are 260lb front and 200lb rear and don't drop the height of the car at all but still have the spring rates that are equal or even higher than most lowering springs. Those paired with good camber plates and Bilsteins sound like the perfect combination for you.

Whiteline's new LCA's that have the Max-C bushing in them seem to be the best of both worlds. Unbinded (is that a word?) articulation but without the noise that traditionally accompanies that amount of movement.

 

[Sky Render]

Vince, have you tried dynamat on the entire area under the rear seat?
It helps to knock down a great deal of the transmitted noise being amplified by the sheet-metal floor pan.

No, I haven't. Any idea how much that would weigh? I'm not normally a stickler for "add more lightness," but I don't want to add 100 pounds back there, and I remember Dynamat being heavy from back during my 3,000-watt sound system ricer days.