Your opinion of how the GTO handles

[MLTTASK]

I inadvertantly sabotaged the '05 picture thread in the other forum, so I thought I'd take the conversation here.....

I wanted to ask those of you who have had the car to the track, and especially those of you who have driven different cars at the track, what you thought of how the GTO handles.

According to the rag-mags, it seems the GTO has a fairly low lateral g measurement, .88g as about the highest I've seen measured. That, added to the pictures shown of the cars on the track in the other thread, combines to suggest to me that there may be some handling issues, especially with weight transition, inheriant in the car.

I've STILL got transition issues in my SS that I haven't solved. It just takes too long to snap side to side for my tastes, and I've rod-ended and adjustable shocked just about everything I can.

If you could give me your thoughts, it may help me pre-prioritize some suspension upgrades prior to getting an '05.

[beertestr]

I inadvertantly sabotaged the '05 picture thread in the other forum, so I thought I'd take the conversation here.....

I wanted to ask those of you who have had the car to the track, and especially those of you who have driven different cars at the track, what you thought of how the GTO handles.



If you could give me your thoughts, it may help me pre-prioritize some suspension upgrades prior to getting an '05.

I posted this on LS1tech.com back in October (you know, when it wasn't snowy?

Executive summary, and things I have found.

2005 will have upgraded brakes, but caliper brackets are drilled for 14mm bolts. I think I will make spacers and hope I don't need the thicker bolts.That should solve the brake problem.

CAPA performance in Australia has an offset strut bushing that moves the strut tube in 12 mm. Any more and my buddies at Holden say the stock springs will rub the strut tower. Nobody has them in the US yet, but I am talking with some shops to ssee if they can start stocking them.


Gravana tuning and I think SLP have stiffer swaybar bushings, this should help steering response and get the swaybars involved sooner. Gravana also has a caster kit that reduces caster deflection in the suspension, I thin k that will go a long way too. There is some steering change under hard braking, trail braking requires some countersteering to keep your line, and I think this might be either from the goopy full-tread tires, or the caster compliance. If I need more camber, I will play with wheel spacers and use the camber adjustments more, , or slot the cradle where the LCA bolts in and push the bottom of the tire out. Either way, it should help tuck the tire into the fender a bit and allow a 255/40-17 if there is a tire like that if not, a 255/45 is only 4mm larger radially. Coilovers are hella expensive, and everyone I looked at has strut tubes thicker than stock, so clearance to the tire is worse. If you put a threaded sleeve over the stock strut (they are cartridge -type so you can pull the damper unit out and weld on the strut body) you lose clearance too, but pick up room in the strut tower from the smaller springs.

I think with the right wheel you can get 255's to fit in the front. Apparently you can go 275 in the rear, but until I get the rear diff to bite better, or I get more power, more rear tire is useless in the corners. PErhaps my opinion will change once I get the fronts to bite better. I NEED SOME CAMBER!!

Rear diff. Look at the banners on the right, Diff technics has ahigher pre-load clutch-pack springs. While this will promote more understeer, I hope it will help getting out of tight right handers. Left turns were more tolerant of hard powering.

I will probably run more rear bar, hopefully Hotchkis will have a set soon, last time I checked their website, they were not in stock yet.

Seats. While the seats are nice, they still do not have great lateral support for hard conering. I think I might try to find a race-seat for track days. At the very least, I will be getting a set of 4-point belts to hold me imn place better.

I will be going to RA1's. I think the BFG's are garbage and my chunked tread proves it. I drove a Monaro with Yokohama's, and it was a whole different animal, it was almost twitchy on ruts in the road. I now give tire selection a much higher priority on my list of mods.

I have driven a 4th gen hard on back roads back to back with a Monaro/GTO, and you can get more lateral g's out of an f-car, but the ride is much stiffer, and you can't trailbrake as deep into the corners if they are not perfectly smooth. Too much axle oddities going on in the F-body. much more visceral too, and on a smooth road course, I'd pick the f-car, at Nelson Ledges, I'd take the GTO hands down.

OKay, this is the original post.

I took my car to Grattan Raceway (www.grattanraceway.com) yesterday for some open track time, and learned quite a bit about my GTO.

1- The stock BFG's can't take open tracking. I chunked the tread pretty bad on the fronts.

2- More front brakes are a must. I was running PF pads for a C5 (there is another post on that), but the rotors were not up to the task, and I boiled the fluid. Time for a brake upgrade.

3- The car need more front camber, or more camber gain. I have seen worse, but I chewed up the outer two tread blocks on the fronts. I another degree might help the problem. As far as body roll, it was pretty good for stock..

4- As usual, the stock car is set up to understeer. This sucked, and it took some hard lfogging to get the tail to come around. I think the posi needs more pre-load too, as the inside can get broken loose pretty easy..

5- Run the oil level 1 quart high. I had the oil light come on once on a hard right hander with hard suspension inputs. I tossed in an extra quart, no probs..


The rest of the car RAN AWESOME!! I got 100 miles out of a tank of gas, 6 mpg indicated on the DIC . I had a Thermocouple in the oilpan, the sump temps never got over 275F, without any external oil coolers, but it's good to run synthetic. Engine temps NEVER got above half, on a 65 degree day. I was running with some guys with A-sedan cars. If I could get the car to corner a bit better, I could out lap them, no prob. Sure, I had 5.7L, they had 5.0L, but they had slicks (maybe very worn R-compound treads) and weighed 1000# less.


Next time I go back, I will have:

- More front camber
- Better tires
- Better brakes
- I'll probably leave the passenger and rear seats at home, and the spare tire in the pits.
-Maybe a gell cell.
- I wonder if the BMR strut tower brace really does anything, I'll might try it out.

[MLTTASK]

^^^ This post is pure money. Thanks

[RA7 GTO]

Feels like a Buick compared to my '99 SS. Feels like a school bus compared to my Z06. The brake and gas pedals are a full 3 and 1/2 inches apart, making heel/toe difficult. At the same time, the seats are excellent and the ride is extremely comfortable.
But that's all about to change.

[Doc GTO]

On the corner weights the car is great. 54/46 front to rear and 50.1 and 49.9 corner weight. All it needs are stiffer springs and firmer shocks, R compound tires, bigger brakes (at least in the front), pads, fluid, and at least 1.5 degrees negitive camber on the front! Oh, and a good driver!!!

[Tails]

It's all about setting it up in the turns. The local track has 10 turns in a 2 1/2 mile course. I had no trouble getting ahead of the M3's and the Cobras. About even with the Z06's and had my butt handed to me by the Enzo Ferrari and Mazerati. The 04's definitely could use bigger brakes if you are serious about racing.

:drink::drink:

[OldER Goat]

took the gto to the track today - the old texas world speedway (college station tx) 2.9 mile road course. i must say that the gto's performance exceeded my expectations. the gto was able to make even a novice road racer (me) look pretty good running against some well prepared and well driven cars. was totally out gunned by all the usual suspects (z06s / z07s, misc race prepped machines). I ran 5 20 minute sessions - OE tires held up well, brakes performed OK (car is 100% OE). i think the earlier posts (obviously by guys more qualified than me) are spot on - but what car wouldn't improve at the track with better breaks, tires, shocks, springs, etc. im now convinced that in the hands of a qualified driver - "this dog can hunt". all-in-all a fun time and im looking forward to the next track date - where i hope to further improve my meager skills.

[OldER Goat]

heres one right after smoking 2 z06s and a mti z07 in the same corner :gr_jest: :gr_jest:
http://www.ls1gto.com/forums/attachment.php?attach mentid=6152&stc=1

[OldER Goat]

installed quickor rear sway bar, C5 ceramic pads, and rip shift and went to track (TWS). no other mods yet. shaved 4+ seconds from my previous best lap (2:19 down from 2:23) ! sway bar was most responsible for the improvement - nice and neutral now. next are tires, maybe wheels too - OE goodrich are not well suited for track use.

[kaiser]

Just curious on what cars you were able to keep pace with on track. Did you happen to run against any e46-M3's? Its nice to see only a few mods made such a difference out on track.

Your car looks good on track and i'd have to say i will go wingless too when i eventually get mine.

[Edmundo]

It would seem the GTO benefits from a late apex approach, given the weight and inherent handling characteristics.

[RedhotGTO]

heres one right after smoking 2 z06s and a mti z07 in the same corner :gr_jest: :gr_jest:



SWEET Pic!

[OldER Goat]

Did you happen to run against any e46-M3's? Its nice to see only a few mods made such a difference out on track.

there are usually several late model M3s at TWS on race`weekends - i think that a stock gto with a decent driver can be reasonably competitive with em - except for the full-tilt dinahs, of course. the gto has much greater potential on the track than im able to take advantage of - being a novice and all - so its hard for me to say. i ran pretty well with a couple of mildly prepped c5s all day, tho - no problem - but i may have been trying harder than they were.

[bellwilliam]

just got back from Willow Springs Street course. This is a very tight / twisty course. GTO's SUCKS at this track !!

Mod (all done within a week from the track day):
1. flush the brake fluid, and install ATE type 200 brake fluid (536/392 boiling point), this is better fluid than Valvoline Synpower (503/343 boiling point) that seems to be favorite in this forum.

2. installed C5 Hawk Plus brake pad, this is supposedly to be a track pad, paid $120 at tirerack.com. they squeal quite a bit, and don't work well when cold.

3. installed Kumho MX tire of same size.

Weather at the track: 60-85F

Pro:
1. car handles nicely with good feedback, understeer weren't too bad, I ran 3psi higher at front tire.

2. Nice low end power for powering out of corner.

Con:
1. Brake sucks comparing to other cars. I drove a Z4, MUCH better brakes.

2. after about an hour on track, my brake fluid boiled. This is at 85F weather, imagine what happens during summer, where it is 100F plus !!

3. Kumho MX couldn't handled the heat. I usually turn my best time within first few laps of the session. after tires heated up, it started to lose traction fast. I believe this is a GTO weight issue, as Kumho MX tire is one of the better tire regarding to heat.

4. stock GTO size is undertired. Base C5 Corvette has the same engine, weighs 500lb less, and uses wider 275/40-17 tire. This is probably why my tires overheated so fast.

Fix:
1. went to my mechanic today to switch out the brake fluid to Motul 600 fluid, rated at 585/421. my old ATE brake fluid (less than a week old) was brown and murky !! probably from boiled over.

2. try to find the largest size tire that will fit my stock wheel. Searched all over this forum, but I don't know of anyone installing different size tires. There is only one poster who installed 275/40-17 Nitto drag racing tire at the rear, and he claims Nitto usually runs narrower. Will probably go with aftermarket wheel to search for the widest tires.

3. run a stiffer spring. the reason is actually tires and brakes. with stiffer front, car won't dive as hard on cornering, easier on the brakes and tires. stiffer spring will also put less load on the outside tires.

For comparison.
My time in the Z4 2.5 was within 0.5 second of my GTO time (I only did 5 laps in the Z4). Z4 is completely stock with 16" wheel and runflat tires, fresh off the showroom. it has less power but made it up with WAY better brake and handling. This is a tight course, so advantage Z4.

[No ConeSS]

I thought I heard that the Motul wasn't street friendly (as in, needs to be changed much more often than others due to moisture absorption). I run the ATE (and have for several years) in my daily-driven '96 Impala SS that I autocross regularly. *That* is a heavy car, and not once have I browned the brake fluid (BTW, I run the Hawk HP+ on the front of the SS also). Sounds kind of wierd...

[bellwilliam]

I thought I heard that the Motul wasn't street friendly (as in, needs to be changed much more often than others due to moisture absorption). I run the ATE (and have for several years) in my daily-driven '96 Impala SS that I autocross regularly. *That* is a heavy car, and not once have I browned the brake fluid (BTW, I run the Hawk HP+ on the front of the SS also). Sounds kind of wierd...

autocross doesn't heat up the pad as much as track (30 minutes per session non-stop). also this is in one of the tightest track on the west, street of Willow Springs, it is much harder on the brake, straightaway is may be 1/8 mile long.

not sure about the SS brake system, but GTO's brake is one of the top complaint, so I guess GTO's brake must work pretty hard.

I've heard Castrol SRF is not street friendly, but have ran Motul on some of my other cars in the past w/o any problem. since I will be tracking the GTO, I guess I will need to replace the brake pads at least once a year, so will also flush the brake fluid on yearly basis, if not more.

[No ConeSS]

autocross doesn't heat up the pad as much as track (30 minutes per session non-stop). also this is in one of the tightest track on the west, street of Willow Springs, it is much harder on the brake, straightaway is may be 1/8 mile long.

not sure about the SS brake system, but GTO's brake is one of the top complaint, so I guess GTO's brake must work pretty hard.

I've heard Castrol SRF is not street friendly, but have ran Motul on some of my other cars in the past w/o any problem. since I will be tracking the GTO, I guess I will need to replace the brake pads at least once a year, so will also flush the brake fluid on yearly basis, if not more.

Gotcha! :thumbs: I was just used to 20 min sessions round here. When you add the extra 10 mins at the end... oh yeah, brakes are lovin' you!

[bellwilliam]

I've read here in this forum, a couple of other GTO owners also cooked their brakes at tracks, so I am not the only one.

GTO's stock brake fluid is actually pretty good according to some of the posters, as pretty close to Valvoline and ATE brake fluid in boiling temperature. so may be that's why ATE did not helped in my case. I will report if Motul 600 will get cooked here in the desert track in the summer, over 110F !!!

[QuicksilverGTO]

I have thought about taking my '04 M6 to the track (VIR, Summit Point, Roebling-Savannah, Charlotte, CMP and now Rockingham all within a few hours) when not racing my 325i but it sounds like there are some basics upgrades that are required. Speaking of upgrades, has anyone thought about pulling the useless foglights and running some brake ducting? Even a temporary setup for the weekend. This should help a great deal with removing heat buildup in the front brakes.

And yes, weight is one of the major problems with the GTO. As a street car, I'm very happy with the overall performance, ride, engine, etc. but laps times will come down when people start pulling weight out of these cars, as well as other mods of course. I know the GTO is still too new for most to start stripping the interior bits but trust me, removing weight will make a huge difference. I can see myself streeting the car for about 5 years and then slowly turning it into a trackday car, and evetually into a full race car. I know there is a V8 Club Racing series (saw an ad in GRM) and a GTO Lightweight with coilovers and brakes would be great.

Last year, I took a friend for a ride on the VIR full course in my BMW racecar, after installing a passenger seat and harness set. He's about 210 lbs. After about three laps, he got out and a woman got in. She's about 130 lbs. The difference was amazing! I know that 80 lbs in a 2750 lbs. car with 168 hp is more significant than it would be in a GTO but it felt like I was driving a different car. Handling, braking, and accelerating was much better.

I just found this Road Racing section so I'll read it regularly. And thanks to the guys who have shared your track experiences here.

[QuicksilverGTO]

Seats. While the seats are nice, they still do not have great lateral support for hard conering. I think I might try to find a race-seat for track days. At the very least, I will be getting a set of 4-point belts to hold me imn place better.

Most schools will not allow you to use a harness unless you have installed at least a roll bar in the car. If you have the stock belts on and roll the car, and the roof comes down, you can slide (or will get slid) sideways. If you're in a harness and the roof comes down, you might break your next.

I highly recommend checking with your chosen school before making any mods to your car.

[bellwilliam]

Most schools will not allow you to use a harness unless you have installed at least a roll bar in the car. If you have the stock belts on and roll the car, and the roof comes down, you can slide (or will get slid) sideways. If you're in a harness and the roof comes down, you might break your next.

I highly recommend checking with your chosen school before making any mods to your car.

you are correct. Here in southern California, most clubs will not allow you to run 4/5/6 point harness unless you have a roll bar in the car. Last year out in Willow Spring Raceway, a Mustang flipped, the top was completely crashed flat. the driver walked away because he was sideway below. If he was in a 4 point harness, he definetely would not of made it.

if you Quicksilver GTO is used to racking a 325i, GTO will definetely feel HEAVY !!! at 1000lb more, that's like driving around your 325i with 4 passengers plus trunkful of luggages. One of the thing I found is that you have to baby the GTO around the track. Because it is heavy, tires/brakes all heats up way too quickly, by lap 5, tires are greasy, brake starts to fade. but if you baby it, you can go much further. In my case, fastest time are always in the first few laps of the session.

I am looking into building a brake duct. but don't see any room behind the bumper. may be just a temporary removable one just for the track, that sits below the bumper.

[QuicksilverGTO]

if you Quicksilver GTO is used to racking a 325i, GTO will definetely feel HEAVY !!! at 1000lb more, that's like driving around your 325i with 4 passengers plus trunkful of luggages. One of the thing I found is that you have to baby the GTO around the track. Because it is heavy, tires/brakes all heats up way too quickly, by lap 5, tires are greasy, brake starts to fade. but if you baby it, you can go much further. In my case, fastest time are always in the first few laps of the session.

I am looking into building a brake duct. but don't see any room behind the bumper. may be just a temporary removable one just for the track, that sits below the bumper.

I definitely understand that the GTO is not a light, nimble, track car. I will take it very easy on the car when it's on-track, and I'll do some serious brake upgrades too. If I get serious about it, I'll buy another set of stock wheels and will put a set of R-compound tires on them. With track tires and better brakes, that should make a track day more fun. For now, the BMW racecar satisfies my speed needs.

It's going to snow/sleet/freezing rain here tomorrow and my BMW race car is in the one-car carport. After we get some better weather, I'll have a look at brake ducting for the track. If you figure anything out before then, please share it with us.

Thanks.

[bellwilliam]

After we get some better weather, I'll have a look at brake ducting for the track. If you figure anything out before then, please share it with us.
Thanks.

I did a quickie install of brake duct. took off the fog lights, ran a 2 inch hose behind it to the brakes. it is just a quickie, to see if it will help this weekend (running at California Speedway). to do it properly, will need to run a 3 inch hose instead.

I also installed a SLP rear sway bar. definetely less understeer now, will see if it helps at the track.

btw, I took off the plate at the bottom of the engine. weigh it, it is only 15lb.

[mkiv97tt]

Just curious on what cars you were able to keep pace with on track. Did you happen to run against any e46-M3's? Its nice to see only a few mods made such a difference out on track.


For the 2.9 mile TWS course with decent drivers, some comparison lap times:

1:54 Lotus Elise (stock w/ street tires)
1:55 '04 Z06 (stock w/ street tires)
2:04 '02 1LE f-body (race tires)
2:05 Spec RX-7 (lol!)
2:06 '01 base Boxster (stock w/ race tires)
2:10 '97 Del Sol VTEC (stock w/ race tires)


Race tires make about a 2-4 second per lap gain over street tires (depends on the street tire.)

[LS1 Overfiend]

Well Not I'm not gonna get into technical analysis and all that crap, but in july, i threw up a couple of cones from work and tried a couple of autox patterns (straight, curved, and circular) to see how the car would take them. I was impressed that the car was very stable though the turns. After I was chased off the property by security, I tried a couple of parkways that had lots of twists. Again, I was pretty impresed!

The only thing that bugs me is the "Squat" so notoriously known throughout this forum. If I can get Some springs like the King Zeros for the rears and Koni adjustables, camber kit and a hotchkis sway bar kit to swing her big ass better, then I should be able to swing with streetable bmw's . But first, a BMR bar and engine torque damper kit, and just got my hands on a set of michelins 235/45/17 front, 245/45/17 rear. I figured if the sidewall is thinner in front and more square on the rim, I can get more grip per turn. I'll definitely report back on the results.

If you ever see the video clip from the 30+k car shootout, on trackday, the GTO was disqualified because of the BFs chunking out. I'll probably buy Kumho asx's new to see how they handle... when the michelins go.

So by december this year.... bmr bar,hotchkis sways f+r, King springs, Konis, and a Adjustable camber kit for the rears only.

[MrT]

I am not going to jump into the geometric principle's of automotive suspension design, but I will talk about the wonderful inherent characteristics that the GTO has.

Overall, the initial turn in capabilities of the car are very impressive. This is due to the width to length ratio, steering, but more importantly the weight distribution.

Also, as seen on many videos, the car is very very controllable in a skid (or drift as you all call it now). When, not if, the rear starts to out accelerate the front the car is very easily controlled with slight steering inputs.

What could best improve the GTO?
1. Rear bar, this will keep the rear tracking with the front after the initial turn in and help to resist skid tendencies
2. Tires. Truthfully, the stock size is very adequate because once you increase the foot print in the rear you induce more scrub which destroys the cars ability to transfer weight from right to left (or left to right) in a turn. However, if you can get more grip to accelerate out of a turn, this trade off may pay off for you. Depends on the track.
3. Camber adjustments (depending on your tire's reaction and compound). Keeps the load radially into the tire, not laterally. But, it will chew your tires up and definitely reduce your tire life and daily drive-ability. Its also pretty hard on your bearings and rod ends, but I am pretty sure that they designed this car to be driven hard so bearing life shouldn't be a problem. Anyone ever changed the wheel bearings yet? I am curious to how long they last.
4. Front shock stiffening, more in the rebound, not jounce(compression). Keeps the load transfer on the inside tire for a split second longer when turning hard and allows quicker reaction when swapping from left to right or vice versa.

Steering wise I haven't had a chance to measure whether the car has Ackermann or not, but it is probably just parallel steering. Most road cars don't use any Ackermann (or anti) anymore because it is not good for tires and it depends on the speeds you are driving. I can't recall which you want for slower sharper turns versus high speed sweepers.

[OldER Goat]

For the 2.9 mile TWS course with decent drivers, some comparison lap times:

1:54 Lotus Elise (stock w/ street tires)
1:55 '04 Z06 (stock w/ street tires)
2:04 '02 1LE f-body (race tires)
2:05 Spec RX-7 (lol!)
2:06 '01 base Boxster (stock w/ race tires)
2:10 '97 Del Sol VTEC (stock w/ race tires)


Race tires make about a 2-4 second per lap gain over street tires (depends on the street tire.)

I had a staggered set-up of RA1s (245 f / 275 r) for several track days at TWS last year - which helped immensely. Best laps were in the 2:05 range. Shooting for 2:00 this season - not sure if Im good enough for that - even tho the car may be.