Lowering GT350R ...is it worth it? (Eibach, FP and BMR)

[ShatterPoints]

do you mean as in getting aftermarket shocks? When I spoke to the Ford performance tax he said the springs were designed for my stock shocks and that I wouldn’t have to reset them or re-calibrate them everything would work appropriately.

The shocks on your car have a range of force they are capable of generating. Lets just say that number range is 1-10 and your OEM springs require ranges 2-8, that is within the designed performance profile. Now take your FP aftermarket springs, lets say they require the shock to perform in ranges 4-9, that still works and you can say that those springs will work with the OEM shock. It's not that the spring itself is designed for the shock, rather the shock has the ability to dampen a range of spring rates, and like anything you can miss match them and get to a result that is outside the range the shock is capable of performing in.

A rule of thumb is you can move +/- 30% from the OEM spring rate and still have relatively ok performance, this is less true the further away from sports car you go (for example a prius).

Sponsored

 

[Driveway Demons]

The shocks on your car have a range of force they are capable of generating. Lets just say that number range is 1-10 and your OEM springs require ranges 2-8, that is within the designed performance profile. Now take your FP aftermarket springs, lets say they require the shock to perform in ranges 4-9, that still works and you can say that those springs will work with the OEM shock. It's not that the spring itself is designed for the shock, rather the shock has the ability to dampen a range of spring rates, and like anything you can miss match them and get to a result that is outside the range the shock is capable of performing in.

A rule of thumb is you can move +/- 30% from the OEM spring rate and still have relatively ok performance, this is less true the further away from sports car you go (for example a prius).

Oh ok so a ride height sensor reset/calibration at the dealer would correct this?

Here is the spec sheet from the 2020 supplement, can’t believe -0.10 toe out holy crap. I guess this is what my handling pack 2020 came with. Drives smooth and straight at 100+.

 

[ShatterPoints]

I'm not entirely sure how the magnaride communicates its data via the sensors, or what is the primary sensor responsible for the change in shock settings. If you lower your car it would change the correction factor used to calculate the wheel or chassis acceleration. I would get it re-calibrated if you go lower.

Front -0.10 (toe out) helps with turn in and is something you want. +0.30 rear (toe in) is already giving you a lot of understeer. That does not mean it is causing the car to understeer, rather it is contributing to the total understeer/ oversteer balance.

"Rear toe has similar effects to the front toe except, in a rear wheel drive car, rear tires continue to be loaded unevenly through much of the corner exit and not just in the mid corner phase. A car with negative rear toe will want to rotate into turns - the rear end of the car will tend to swing out around the car's center. A car with positive rear toe will tend to keep its rear tires following the front tires; it wil tend to be stable under braking, especially when braking in curved paths. A car with negative rear toe will tend to rotate eagerly under trailbraking, and could easily go into a drift under trailbraking or with aggressive (high steering angle) corner entries.

When exiting corners, negative rear toe will tend to make the car oversteer under throttle (this would be power oversteer). A positive rear toe will tend to make the car understeer - the rear tires will follow the front tires, and will push the front tires forward in a straight line."
#source: http://racetrackdriving.com/car-setup/track-alignment/

 

[Driveway Demons]

I just spoke with Steeda about their 555-8243 dual rate springs. Front 220 lb/in rear 800 lb/in. Dual rate takes only little over 5/8" of suspension travel to immediately go into dual rate 350 lb/in front and 1200 lb/in rear. From what I gather these springs are going to be very similar to what I have now (201 lb/in front, 864 lb/in rear) slightly softer in the rear and slightly stiffer in the front. Overall very balanced and better traction for drag racing and launching light street driving is also more comfortable. However even the slightest turns into the dual rate and its going to be stiffer than GT350R and with 1200 lb/in rear its going to have slight oversteer.

Looks like we have ourself a definite winner and has 0.5" drop all around. So its basically a GT350R drop but has dual rate. DAMN.

 

[Driveway Demons]

I'm not entirely sure how the magnaride communicates its data via the sensors, or what is the primary sensor responsible for the change in shock settings. If you lower your car it would change the correction factor used to calculate the wheel or chassis acceleration. I would get it re-calibrated if you go lower.

Front -0.10 (toe out) helps with turn in and is something you want. +0.30 rear (toe in) is already giving you a lot of understeer. That does not mean it is causing the car to understeer, rather it is contributing to the total understeer/ oversteer balance.

"Rear toe has similar effects to the front toe except, in a rear wheel drive car, rear tires continue to be loaded unevenly through much of the corner exit and not just in the mid corner phase. A car with negative rear toe will want to rotate into turns - the rear end of the car will tend to swing out around the car's center. A car with positive rear toe will tend to keep its rear tires following the front tires; it wil tend to be stable under braking, especially when braking in curved paths. A car with negative rear toe will tend to rotate eagerly under trailbraking, and could easily go into a drift under trailbraking or with aggressive (high steering angle) corner entries.

When exiting corners, negative rear toe will tend to make the car oversteer under throttle (this would be power oversteer). A positive rear toe will tend to make the car understeer - the rear tires will follow the front tires, and will push the front tires forward in a straight line."
#source: http://racetrackdriving.com/car-setup/track-alignment/

Nice! So basically -0.10 toe front 0.30 toe rear is really a great balance to keep the rear tight and get proper steering. I haven't installed the dealer handling pack upper strut tops. I have the factory strut tops now. I wonder if that's the specs my car has now? My tires in the front have a very very slight uneven chop at 2000 miles on my car now. However at high speeds on the highway and in the turns the car is a beast and smooth!

Also read my post above, I think I found my springs. Do you think they are a good choice?

 

[ShatterPoints]

Nice! So basically -0.10 toe front 0.30 toe rear is really a great balance to keep the rear tight and get proper steering. I haven't installed the dealer handling pack upper strut tops. I have the factory strut tops now. I wonder if that's the specs my car has now? My tires in the front have a very very slight uneven chop at 2000 miles on my car now. However at high speeds on the highway and in the turns the car is a beast and smooth!

Also read my post above, I think I found my springs. Do you think they are a good choice?

For me I'd say the steeda springs would be ok if the lower rate was used more, you might be ok with a stiffer ride overall. The front's dual rate of 220/350 is ok, the rear of 800/1200 the higher rate is way stiff for no good reason. I called them to double check that, they said it's actually 3/8" travel to activate the dual rate, and the 1200 lb/in rate is accurate. Hopefully one of their engineers calls me back with MR or WR for the car, now I am curious.

 

[Driveway Demons]

For me I'd say the steeda springs would be ok if the lower rate was used more, you might be ok with a stiffer ride overall. The front's dual rate of 220/350 is ok, the rear of 800/1200 the higher rate is way stiff for no good reason. I called them to double check that, they said it's actually 3/8" travel to activate the dual rate, and the 1200 lb/in rate is accurate. Hopefully one of their engineers calls me back with MR or WR for the car, now I am curious.

you seem very knowledgeable and suspensions. In your honest opinion do you think that the Cedarsprings that I’m looking at would be better for the Ford performance? I want to drop but I want the car to perform like it does now. It doesn’t necessarily have to get a lot better as long as I get very similar to what I have right now. Which ones do you think are the better choice to get as close to what I have right now?

 

[ShatterPoints]

you seem very knowledgeable and suspensions. In your honest opinion do you think that the Cedarsprings that I’m looking at would be better for the Ford performance? I want to drop but I want the car to perform like it does now. It doesn’t necessarily have to get a lot better as long as I get very similar to what I have right now. Which ones do you think are the better choice to get as close to what I have right now?

I'd honestly go with BMR springs. I called them and they drop the rear more because it is already higher than the front. So their 0.30 and 0.50 drop makes the rake about even.

 

[Driveway Demons]

I'd honestly go with BMR springs. I called them and they drop the rear more because it is already higher than the front. So their 0.30 and 0.50 drop makes the rake about even.

Their spring rates look great. I just love the look of the slight rear (beefy rake). Also its weird because the front has more wheel to fender gap than the front. This would make it look worse that's the only reason I didn't pull the trigger on BMR yet. If they had .5 all around I would have already got them.

 

[ShatterPoints]

Their spring rates look great. I just love the look of the slight rear (beefy rake). Also its weird because the front has more wheel to fender gap than the front. This would make it look worse that's the only reason I didn't pull the trigger on BMR yet. If they had .5 all around I would have already got them.

Looking at pictures, you would have to go with the 305 front tire to fill that fender gap with the BMR springs, otherwise its just a result of the way the fender looks in relation to the wheel + ride height.

 

[Driveway Demons]

Another thing I don’t get is why the 2019 and 2020 have completely different toe and camber in the different owners supplements.

I plan on one of these alignment setups:

1.
Front camber = -1.16
Front toe 0.06

rear camber = -1.20
Rear toe = 0.30

2.
Front camber = -1.16
Front toe 0.06

rear camber = -0.70
Rear toe = 0.30

it seems that in the 2020 supplement it calls for -0.11 toe out. This will help with darty oversteer and going into the corner but typically load is transferred to the outside wheel where the toe out would cause understeer going into mid turn and apex to exit. Which is the rear toe is set to 0.30 to keep the rear following the front tires.

With the 0.06 front toe it will be a slight understeer when entering the corner but into mid turn and apex it will shift outside wheel and have more oversteer and still stabilize on exit. It’s also better in straight roads to have 0.06 over -0.11. It’s not only less toe but more stable on the highway.

the rear camber set to -0.70 would help with contact patch and street/drag traction as well as apex exit, it will also help with the understeer of the 0.06 and because the toe is 0.30 in the rear will balance the equation. Rear being set to -1.2 would be better in the entry to mid turn and less on exit also less contact patch.

what do you guys think?

 

[ShatterPoints]

Pretty solid on the alignment. Remember whatever you are driving on the most will decide what camber you will have to run. Flat streets give you a lot of flexibility as flat does not require a lot of camber. If you go to a track which requires a lot of camber like COTA or Wakins Glen then you'd want to dial it up front and rear. The supplement card gives you a pretty good starting point. Personally I'd run +/- 0.10 toe for each degree of camber. Meaning I'd run -0.10 front toe and between 0.10 and 0.30 rear toe. There is a crazy debate about ackerman (toe out in the front) as there is what oil you should use. You will find with toe out in the front the car will want to turn in more than if you use toe in.

 

[Driveway Demons]

Pretty solid on the alignment. Remember whatever you are driving on the most will decide what camber you will have to run. Flat streets give you a lot of flexibility as flat does not require a lot of camber. If you go to a track which requires a lot of camber like COTA or Wakins Glen then you'd want to dial it up front and rear. The supplement card gives you a pretty good starting point. Personally I'd run +/- 0.10 toe for each degree of camber. Meaning I'd run -0.10 front toe and between 0.10 and 0.30 rear toe. There is a crazy debate about ackerman (toe out in the front) as there is what oil you should use. You will find with toe out in the front the car will want to turn in more than if you use toe in.

doesn't toe out make the mid turn and apex/exit more difficult? So I was thinking less camber in the rear to help give more oversteer.

I am leaning towards -1.16 front and -0.7 rear. What do you think between +0.6, +0.10 and -0.10 toe? Doesnt Toe out (negative toe) wear tires more and also make the car less stable on the highway?


Also the sheet says "Toe-Total" so when it says 0.30 for the rear does it mean 0.15 per side? Same with the front -0.10 would be -0.5" per side?

 

[ShatterPoints]

doesn't toe out make the mid turn and apex/exit more difficult? So I was thinking less camber in the rear to help give more oversteer.

I am leaning towards -1.16 front and -0.7 rear. What do you think between +0.6, +0.10 and -0.10 toe? Doesnt Toe out (negative toe) wear tires more and also make the car less stable on the highway?


Also the sheet says "Toe-Total" so when it says 0.30 for the rear does it mean 0.15 per side? Same with the front -0.10 would be -0.5" per side?

No, toe out in the front will not make steering more difficult. Less camber is fine for the street, not fine for the track. Your camber numbers of -1.16 and -0.7 are fine. ANY toe or camber will cause the tire to wear sooner than if there were zero toe or camber. If you have too much toe or camber the tires wear unevenly which will lessen their lifespan even more. Expect ~ 12-15k miles with the toe and camber settings you're thinking about doing. That number could be lower or higher depending on your driving habits.

Yes you have it right with the "total toe" it will be 0.05 per front (IMO you can go +/- 0.10 in the front, that will not affect tire wear too much) and the rear would be 0.15 per side which again is totally solid.

 

[Driveway Demons]

No, toe out in the front will not make steering more difficult. Less camber is fine for the street, not fine for the track. Your camber numbers of -1.16 and -0.7 are fine. ANY toe or camber will cause the tire to wear sooner than if there were zero toe or camber. If you have too much toe or camber the tires wear unevenly which will lessen their lifespan even more. Expect ~ 12-15k miles with the toe and camber settings you're thinking about doing. That number could be lower or higher depending on your driving habits.

Yes you have it right with the "total toe" it will be 0.05 per front (IMO you can go +/- 0.10 in the front, that will not affect tire wear too much) and the rear would be 0.15 per side which again is totally solid.

Thanks for chatting with me about this! Do you think +0.10 or -0.10 would be more stable at highway speeds? I wish I could have found out what settings my car had stock. It drove amazing.

I want to have slight oversteer and good spirited driving in the streets/mountains and highway. Do you think my specs would setup that right? Or do you think I would need more or less negative camber in the rear?

I feel like stock it was -1.1 front and -1.2 rear. But I want to compensate the softer spring rate in the rear so I figured less camber on the rear would promoted oversteer. Thats why the R came with -0.7.

These springs handle very good. Cant wait to dial it all in. You think I should leave the rear -0.7 or go -1.2? I am still deciding if I should go +0.5/0.10 or -0.5/0.10 on the front toe.

Sponsored