G50 : 1990 Q45 Road Test - Braking From 60 MPH in 108 FT. ??

[lino]

I was watching a video on YouTube of a road test on a 1990 Q45 and they said that their test car only needed 108 FT to stop from 60mph on average. How were they able to achieve those results?

Video link:http://www.youtube.com/watch?v=zcGOqYmLfDY







Here are some 60-0-MPH Braking figures from http://www.motortrend.com/road....html:

PORSCHE 911 TURBO.............111 ft FERRARI F355 .....................114 ft TOYOTA SUPRA TURBO..........115 ft CHEVROLET CORVETTE..........116 ft MITSUBISHI 3000GT VR-4......116 ft ACURA NSX-T......................120 ft DODGE VIPER GTS................129 ft

[Q45tech]

Note light weight FORGED wheels and Michelin Sport XGTV tires [wear rating 160 most were done by 16,000 miles to match the bake pads] on test video

OEM only promised 129 feet but it depended on which set of pads you received especially after the first 15-18k pad replacement. [90% of customer howled about dust and wear]If you complained you received 1 of 2 option pads to increase life and tolerated the increase in braking distance.

These ultra fast wear out pads disappeared by 1994. I bought 6 sets which lasted thru 120k after that [since 1998] oem pads were just adequate.

Easy with very very very very soft fast wearing tires of the proper design!Easy with fast wearing oem pads [and match oem rotors] of the proper design!

Very difficult with tyoical tires which have a life over 20,000 milesVery difficult with pads or hard rotors that last over 22,000 miles

The 90Q had an extraordinary amount of rear brake basis [help by VLSD] and the very aggressive ABS software [changed as the model progresses after 90 due to customer complaints].

In many ways the 90 was way too raw for the typical US purchaser, these rough edge were redesigned out in 1991 model which sucked

[Q45tech]

Based on the hundreds of different Q seen for service since 1997, my estimate is that most of them won't even stop in 140 feet due to tires and pads and especially heavier than oem wheels!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

[AZhitman]

lino -

Keep in mind, the '03 G35 Coupe with Brembos "outstopped" its smaller, lighter cousin (350Z) as well as that year's 'vette.

The earliest Q's were, as Dennis said, very raw. Most are but a shell of what they once were, due to poor maintenance and neglect.

To this day, NO ONE has been able to replicate the performance of the ACTSUS Q45 for under 6 figures.

The answer is simple: That car was WAY ahead of its time.

[maxnix]

The 90Q had an extraordinary amount of rear brake basis [help by VLSD] and the very aggressive ABS software [changed as the model progresses after 90 due to customer complaints].

Don't recall a front to rear brake bias adjustment on the G50 so I will review the FSM in the brake section.

Wouldn't a more "aggressive" ABS software just intervene earlier? After all, ABS operation is limited by tire traction and surface coefficient of friction and sampling rate and ABS controller reaction time, which I assume the ABS controller didn't vary substantially between model years.

[lino]

Note light weight FORGED wheels and Michelin Sport XGTV tires [wear rating 160 most were done by 16,000 miles to match the bake pads] on test video

You've always said how important tires, brake compounds and wheels are. I'm just surprised how much of a difference it makes. So in that test the car had the 15' BBS Forged wheels, Michelin XGTV Sport tires, and the 41060-60U90 brake pads? Is that right?

How do the Pirelli P600 tires compare to the Michelin XGTV Sport:http://www.tirerack.com/tires/...cQty=

The 90Q had an extraordinary amount of rear brake basis [help by VLSD] and the very aggressive ABS software [changed as the model progresses after 90 due to customer complaints].

In many ways the 90 was way too raw for the typical US purchaser, these rough edge were redesigned out in 1991 model which sucked

What component on the 1990 had the aggressive ABS software?

[maxnix]

You've always said how important tires, brake compounds and wheels are. I'm just surprised how much of a difference it makes.

How do the Pirelli P600 tires compare to the Michelin XGTV Sport:

So are most people who skimp on tires and fit heavy and weak wheels to complement them.

The P6000 is almost as round as the Michelin and has a similar amount of rubber, but no tire is quite as true as H rated and above Michelin (each one is x-rayed).

If you want 1990 OEM performance, get some forged 18" Rays (RE30 from Joe) or BBS (RGR GT) and PS2. Goodyear F1 GS D3 comes close, as should the Pirelli P Zero.

Everyone one else is in second class or in the cattle car if they even caught the train.

[AZhitman]

Don't recall a front to rear brake bias adjustment on the G50 so I will review the FSM in the brake section.

There isn't one. That's not what Dennis said, he said the early one had more rear bias.

[maxnix]

There isn't one. That's not what Dennis said, he said the early one had more rear bias.

Something had to set the front to rear bias, no?

[Q45tech]

Besides the master cylinder which was changed and redesigned internally in 1991 [due to short life and leaks, the pad compounds set the effective brake balance.

You can set the pressure or you can change the pad compund hardness.

In 1991 there were 3 different pads available and it got worse in subsequant years with a different pad model for each year.

It was a nightmare and most dealers only stocked a few not all and many Q got mismatched as far as brake bias was concerned but the ABS fixed that unless you wanted 1990 braking distances.

TODAY the only OEM pad available is the 1994 series and the 1995-1996 series

Remember the orginal pads were worn out before 20,000 miles whether the driver was agressive or a grandpa!

They unintentionally designed the system to be replaced [rotors, pads, fluid] every year [20,000 miles]!

The easy way to measure the TRUE ACTUAL brake bias is to measure the rotor temperature RISE after a series of stops QUICKLY before much cooling takes place.

The ABS software and pump were redesigned in 1994.Because the average lux driver in Japan drove 5,000 miles in a year not 15,000 as in US as they later found out! Whoops and double whoops

Tire Rack provides a braking distance which can be reverse engineered into an effective deceleration G rate.

The FSM contains enough data to derive front and rear swept area and the pressure and proportional pressure is given so the True brake bias at least to the pad backing plate is available.All that is left is to measure the frictional coefficient of pads vs temperature and speed.

Unfortunately the are no examples of the 1990 original pads to test.

One might correlate the orginal 2002-2003 G35 very very dusty and short lived oem pads which also wore out prior to 20,000 miles.

Have you noticed that the G35 gets larger and larger diameter rotors [and wheels/tires] with harder and harder pads to try to maintain at launch braking with better wear life.

The wheels in TEST were specials [for TCS cars] forged in Japan not BBS......those wheels were $923 retail each to replace but we still see a few today that are still perfect [in balance and runout] TODAY.

It is unlikely that any Forged wheel in 18" weighs 15.3 pounds as those did, same with Michelin PS2 in that size vs 15" so right off the bat, unlikely that any tire in 18" can meet the 108 feet vs 1990 Q45.

You could design your own brake pads and have them built on oem worn backing plates to get close. But TIRES are a problem

I'll ATTEMPT [ later tonight] to calculate what PS2 and 18" forged wheels might accomplish. Again the problem is today's harder pads.

The equal weight [+- 25 pounds] AMG C63 with 235 and 255/18" PS2 stops in 113 feet.The 100 pound lighter ISF with 19" PS2 stops in 116 feetThe total swept area is 629 for AMG and 606 sq.in fof ISF

[lino]

If you want 1990 OEM performance, get some forged 18" Rays (RE30 from Joe) or BBS (RGR GT) and PS2. Goodyear F1 GS D3 comes close, as should the Pirelli P Zero.

Everyone one else is in second class or in the cattle car if they even caught the train.

I understand the difference between the performance of the different tires, but my question is how much of a difference does the weight of the wheels make?

18" Rays RE30 forged wheels weigh approx. 16lbs each 18" Michelin Michelin Pilot Sport PS2 tires weigh approx. 25 lbs each

15" BBS Factory Q45 forged wheels weigh approx. 13 lbs???? (Can anyone confirm please)15" Michelin Pilot Exalto A/S tires weigh 25 lbs each(I'm assumming that the original Michelin XGTV Sport tires weight approx. the same as the Exalto)

So does the 3 lb difference make that much of a difference? What is the weight of the piepans and what is the weight of the original HICAS forged wheel?

[qship96]

In same car 50-0 mph braking tests performed by tirerack- exact same size PS2 tire stopped 3 feet shorter dry/5 feet shorter wet than the Exalto a/s

[Q45tech]

A serious problem is finding front tires which can maintain their friction coefficient under the overload strees of a 0.9 G panic stop. Even though the stop take less than 3.0 seconds, most tires will give up 2.0 seconds in.

With 4140 pounds and 53% on front and a mild unbalance across due to driver weight the average is 1097 say 1100 for a 150 pound driver.

The problem is tires are not tested [other than braking distance] at 100% load caused by weight transfer from the rear.....................LUCKILY the Q has a 113.4" wheelbase vs 107.5- 108.7 of the ISF and AMG C63 which share the same weight and 54/46 weight distribution.

So in the same G panic stop the Q45 actually has 4-5% less weight shift on the front tires....................give or take a pound the numbers come out to be 42 pounds less on each front tire in a 0.9 G stop..................a little less than 3% less total weight on the tire which should result in 1-1.5-2% better performance........................1-2 feet!!!!!!!!!!!!!!!

A great deal depends on the tire camber [shape of contact patch] when the front drops 2.5" due to weight shift.

This can be tested by using a chain hoist on alignment machine to pull the front down by 2.5 inches need ~~ 730+ pounds then read the camber!

[Q45tech]

If maximum braking and handling is important then the front tires you chose should be stronger than the oem minimal spec 95 or 1521 pounds at full max inflation [44-51 psi].

If you increase rating by 6% expect at least a 2.5% probably 3% improvement........................3-4 feet compared to same tread in weaker tire.

This is even more important braking from 80 or 150 mph as the over heat interval gets longer and longer.

[qship96]

Qtech, what tires are you currently running on your Q, and with what wheels?

[Q45tech]

3rd set of oem 1994 polished 15" wheels and the obsolete and unavailable 235/60/15 Michelin Pilot H load index 98.

Bought some extras before they were out of stock but these are nearly done now. I'll switch to Exalto Pilot A/S in 225/60/15 V in the Fall.

As good as you can get in 15".

[maxnix]

As good as you can get in 15".

Sad but true.

I would imagine that in 20 years, Michelin has improved carcass stability under load, compounds and tread patterns for incremental performance increases.

But Q45tech's comments about OEM pad variation should cause those who want to switch to harder dustless "performance" pads to reflect on the initial cold stop distance increase consequences in every day driving.

[qship96]

3rd set of oem 1994 polished 15" wheels and the obsolete and unavailable 235/60/15 Michelin Pilot H load index 98.

Bought some extras before they were out of stock but these are nearly done now. I'll switch to Exalto Pilot A/S in 225/60/15 V in the Fall.

As good as you can get in 15".

I ran the 235/60/15 pilot H load index 98 tires before switching to the 225/60/15V Exaltos{now on my 2nd set}, you will love the Exaltos- I find them better all around than the 235/60/15h pilot xgt.....last longer too-got 55k with 4/32 tread left on last set of Exaltos{3 years of use}

[lino]

Here are all the G50 wheels listed in Nissan FAST:







So there are 5 different wheels.

Original PiePan -- Part Number - 40300-60U25 - Price: $305.59 - Specs CASTED 6JJ x 15 - O/S 45 --------- Years 08/89 - 01/92HICAS ---------- Part Number - 40300-60U26 - Price: $875.28 - Specs FORGED 6JJ x 15 O/S 45 ----------- Years 08/89 - 01/92 BBS Forged ----- Part Number - 40300-63U25 - Price: $809.65 - Specs BBS TYPE FORGED 15 x 6.5JJ O/S 45 Years 01-92 - 07/95Polished PiePan - Part Number - 40300-64U25 - Price: $280.65 - Specs BRIGHT TYPE CASTED 15 x 6.5JJ --- Years 01-92 - 06/94Turbine Style ----Part Number - 40300-41U25 - Price: $216.09 - Specs 15 x 6.5JJ ------------------------ Years 06/94 -

Does anyone know the weight of each one of these wheels?

Here are some pictures for reference:

BBS In Aftermarket Chrome Finish:

Closeup showing BBS Germany and Nissan stamp:

BBS Wheel with Standard Finish:

Closeup showing BBS Germany and Nissan stamp:

Fellow nico member's beautiful BBS Wheel with Michelin Pilot Exalto M/S

Center Cap

Center Cap Wrench

Piepan In Aftermarket Chrome Finish

Piepan Nissan OEM

Piepan Size

Piepan Part Number

Piepan - Dull Finish

Piepan Center Cap - Dull Finish

Piepan - Bright Finish

Piepan Center Cap - Bright Finish

HICAS Wheels

HICAS Wheels with Center Cap Removed

HICAS Wheel Closeup - Forged

HICAS Wheels Top View

HICAS Wheel Closeup With Cap

HICAS Center Caps Closeup

HICAS Center Cap Back Side

Turbine1995 - 1996 Wheel

Turbine 1995 - 1996 Center Cap

Turbine 1995 - 1996 Wheel In Aftermarket Chrome Finish

Turbine 1995 - 1996 Wheel Specs

[MinisterofDOOM]

With the powerslot rotors and axxis pads (I think they're axxis pads, anyway) on my Q, the brakes feel spectacular. They BITE hard, but they're still progressive and livable. After driving the Maxima, I really had to get used to the braking power of this car (the Max has weenie brakes and drums in the back).

Tonight I had to panic-brake on the highway from about 55 (construction zone, tight quarters, plus idiots not paying attention and king idiot doing 40 at best instead of the posted 55 in the middle lane). Far more than enough braking power. I was able to brake and smoothly transition into an open lane. The car's poise was not upset in the least. Good brakes plus good tires make all the difference.

Just one more reason I love the G50. With just basic brake and suspension upgrades, this 4000lb car is absolutely amazingly well-behaved in even the worst conditions.

I wonder if my G-tech dealie can measure braking distance...