GT350/R and GT500 knuckle comparison.

[XCRN]

Mixing and matching GT500 parts with GT350R parts was covered on a thread where @50 Deep put the GT500 knuckles, calipers and rotors onto his GT350R. The GT500 calipers are much bigger and heavier than the GT350 calipers.

https://www.mustang6g.com/forums/threads/gt500-brake-swapping-the-r.133213/

All that said, if you have any GT350, not just a 2020 R, you could probably put some spacers in and run the GT350 calipers with the bigger GT500 rotors and get away with it, although finding a pad of the right dimensions might be a challenge.

Gotcha, I have not been keeping track of this lately, but that makes sense. I got a bog standard GT but have GT350 knuckles and brakes for all 4 corners I am ready to put on so this just seemed interesting idea, but do not want to deal with the hassle of finding wheels to fit when I already have good 19" tires.

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[Epiphany]

I think it is the exact same casting between the 2. It looks like the only difference is where the caliper mounts are machined at different offsets.

I pointed this out in the video in post #1.

 

[Caballus]

Other than maybe changing to shocks and strut of your choosing. The main step to remember in this part swap is to preload the knuckle before torqueing the bolts to spec, otherwise you end up with a horrible vibration in the suspension.

Did this conversion to my 15 GT to GT350R components with a shock and lowering spring upgrade.

Good points. However, reason I was asking is because significant changes were made to the non-R 19+ suspension--stiffer front springs, softer rear springs, dampers recalibrated, etc. So, given that the calibration and tuning is based on those changes, wonder if it would need to be retuned for a different knuckle to be helpful rather than harmful to all that.

 

[torque124]

It looks like a very minor change but from my experience minor changes have impact on the tramlining. For example:

My 2018 GT350 on PS4 tires, no tramlining at all till after my 2nd track day on an alignment between street and track. So the tire wear and alignment played a role.

My 2019 GT350R on Cup 2 tires quite a bit of tramlining brand new. Had the adjustable camber plates installed and street alignment done, tramlining significantly reduced even on Cup 2 tires. Same alignment installed Signature Wheels and PS4 tires this weekend tramlining completely gone again.

OK. 2016 GT350R with stock alignment (confirmed to be within speck a bit of tramlining on original cup 2 tires and CF wheels. Switched (for street) to Signature wheels and Cooper all season tires, tramlining completely gone. No other change.

 

[mustangguy88]

I was asked a install question about the knuckles going on a 50th Anniversary car. I couldn't email out the file it was to large. So here are the install instructions as written by Full Tilt Boogie Racing, and Ford Motor Company.

The tie rod ends will work without issue, they get corrected with the wheel alignment, and the halfshafts will work as well, I reused my stock shafts until they broke at the dragstrip launching with a butt load of torque.

Again the instruction credit goes to Ford and Full Tilt Boogie Racing, I hope this helps answer some questions.

These are the service manual instructions, from Ford



Here are the instructions from Full Tilt Boogie where I purchased my kit.

View attachment 465078

 

[GT5.0Fan]

Great post, thanks for sharing. Looks like upgrading stock part on Mustang GT then is out of the question. Was looking into seeing what would improve steering sharpness on Mustang GT to get it like the 350R

 

[Epiphany]

Neither of those sets of instructions has anything to do with swapping front knuckles. Good information, just none of it has anything to do with GT350 or GT500 front knuckles.

 

[mustangguy88]

Neither of those sets of instructions has anything to do with swapping front knuckles. Good information, just none of it has anything to do with GT350 or GT500 front

I thought the question was on the rear knuckle. As far as the front knuckle(spindle), their was no need for a change. The GT350 brakes and rotor are a straight install with the addition of a 1" spacer bar between the caliper and the front knuckle included with my kit, then wheel spacees as appropriate for the wheels being used. In my case no spacers were needed.

If the kit being used is from Full Tilt Boogie the spacer is included, if not contact them. The spacer they use is a very effective and simple solution.

As far as improving the steering response on a stock GT setup without the Magna Ride option. A set of progressive rate springs and caster camber plates up front, and springs out back. Made a world of difference in my setup.

 

[Epiphany]

Not clear as to whether he was implying front and rear knuckles in post #16 but it sounds likely that he has the front knuckles.

I know Bruce at FTBR. Great guy and he really knows his stuff. But to be clear, that specific kit allows adapting the GT350 front rotor and caliper due to a caliper adapter bracket. One of the benefits of using all the GT350 hardware (no adapter brackets) is the increased stiffness provided by the GT350 knuckle and hub assembly as well as the knuckle being an optimized anchor point for the GT350 caliper. This increased stiffness translates into a steering feel improvement but more importantly, better feel at the brake pedal. I can't speak to any "measured" improvement but only what was conveyed to me by the engineer behind the entire knuckle and brake package designed for the GT350. This includes why you see a "bridge" on the GT350 front caliper. They wanted the stiffest hardware possible.

 

[mustangguy88]

With the suspension and brake setup I've installed, plus a supercharger and related parts, and having a custom tune written with the speed limiter removed, the car has been upto 185mph on open road. The car felt as good as some of the ZO6s and Porsches I've worked on and test driven up to those speeds.

Unless you are building an all out race car. Minor modifications go a long way. More indepth upgrades and modifications will yield better results. It comes down to budget and mechanical skill sets.

Good luck in your endeavors.

 

[Epiphany]

I hear you and your car sounds like fun. I'm just speaking to the design intent and cannot quote percentage functional improvement numbers or data.

 

[mustangguy88]

I'm coming from an engineering background, looking at the model upgrades from the 350 to 500, the front brakes are larger with a slight weight increase. When you consider the amplified rotational weight increase that turns into at elevated speeds combined with the braking stress loads of the system in a track environment, there is a need for every bit of strengthening that can be gotten as well as reducing as much of the harmonic vibration that occurs the harder you push the car. So any marginal improvement made usually returns substantial durability and performance gains. Otherwise Ford wouldn't have spent the money on a redesign.

 

[JAJ]

I'm coming from an engineering background, looking at the model upgrades from the 350 to 500, the front brakes are larger with a slight weight increase. When you consider the amplified rotational weight increase that turns into at elevated speeds combined with the braking stress loads of the system in a track environment, there is a need for every bit of strengthening that can be gotten as well as reducing as much of the harmonic vibration that occurs the harder you push the car. So any marginal improvement made usually returns substantial durability and performance gains. Otherwise Ford wouldn't have spent the money on a redesign.

So, it looks like when you did your brake swap, you kept the surprisingly flexible GT front knuckles/spindles and didn't replace them with the super-stiff GT350 knuckles, correct? If you already have GT350 front brakes, then the knuckles are a relatively easy upgrade, and it improves brake performance. Folks who track GT's aggressively complain about brake pad knockback, while folks who run GT350's aggressively don't.

 

[mustangguy88]

There's always someone with a smart remark. I don't track my car hard so the stock spindles work just fine for my application, if I wanted a hard track car I would have a supercharged GT350R stripped out for twice what I have spent on this project. As far as easy goes, I make my own carbon fiber parts as needed. I'm not overly challenged at building out Mustangs considering by bread and butter comes from building out considerably more expensive cars for others. Just want to share some info thar others might have been able to use.

Guys like you keep people like me from sharing info We just don't appreciate smart !@##.

 

[JAJ]

There's always someone with a smart remark. I don't track my car hard so the stock spindles work just fine for my application, if I wanted a hard track car I would have a supercharged GT350R stripped out for twice what I have spent on this project. As far as easy goes, I make my own carbon fiber parts as needed. I'm not overly challenged at building out Mustangs considering by bread and butter comes from building out considerably more expensive cars for others. Just want to share some info thar others might have been able to use.

Guys like you keep people like me from sharing info We just don't appreciate smart !@##.

I wasn't aiming for it to be a smart or critical remark. You contributed to a thread in the GT350 section on the topic of GT350 and GT500 front knuckles, so I assumed that you were interested in them as an upgrade or perhaps you had them already. You did talk about "elevated speeds combined with the braking stress loads of the system in a track environment, there is a need for every bit of strengthening that can be gotten", which is absolutely true, and it is, in my view, the big reason that Ford changed the S550 front knuckle when it rolled the GT350 out in 2015.

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