SCCA EMod MGB GT V12 Build

mguar wrote: In reply to loosecannon: Go to a smaller bore master cylinder to get front lock up first.. That is critical to lap times..

I'll wait until my set up is a little closer to ideal before I go that far. I could try grippier brake pads as well.

In reply to mguar:

Sure about that? Ask any STS miata guys about brake biasing pads.

mguar wrote: In reply to loosecannon: pads won't change bias..

Not in terms of fluid, no... But they will absolutely change the actual braking force distribution as different pads have different levels of "grip."

I haven't made any significant changes to the car so I haven't updated this thread but people have been asking so here is an update. I did the math on how many runs the Avons would have by the time we got to Nationals and they would be pretty used up by then so I slapped on a set of old Hoosiers.

The Hoosiers are radials and the Avons are bias so there is a big difference, and since I plan to run wider front tires for Nationals, I used the same size on the front as I did on the rear (going from 10.7" wide fronts to 13" wide). I know I should be running the exact same tires I am going to run in order to set the car up but I don't have the budget to run two sets of new tires per year. I also lowered the front of the top link of the rear suspension to move my anti-squat from 22% to 44% anti-squat. This was done to improve my launch at the start of the run because I felt I was losing a lot of time with wheelspin.

At the last event I was scraping the sidepipes on the pavement in some high G turns so I reduced the body roll by raising the roll center at the rear of the car by one inch. I did this by raising both sides of the Panhard bar one inch. I expected this, in conjunction with the wider front tires, to make the car oversteer. And oversteer it did, anybody watching my first run watched me wrestle with the car to keep it straight. I lowered the axle side of the Panhard 1/4" and tried again, it was better. I continued to lower the axle side of the bar 1/4" for each run and by the end the car felt pretty stable.

Here is a video of the rear suspension during one of my runs, notice that at the 19 second mark, my bellypan hits a bump and gets bent. It looks like there is a lot of lateral movement of the axle but as far as I can tell nothing is flexing or is broken so maybe it's an optical illusion. http://www.youtube.com/watch?v=4bcV12O0V7s

The good news is that the car drives like a high powered S2000, the bad news is that I have never been any good at driving S2000's. I suspect this is because I do so many laps in the karts and they reward smooth driving and very little rear slip angle. My car seems to reward really aggressive driving and a lot of rear slip angle. Here is an in-car of my 4th run http://www.youtube.com/watch?v=AvVlTyKUqAQ

I would have to say it looks like the housing IS moving laterally,I watched the chassis end of the panhard and it sure looks like the heim is moving with load.Is the heim in single shear?,almost looks like its twisting the mount. Of course with the panhard out of level the housing will move laterally but with it looking like the chassis mount moving I think its worth trying to come up with a way to check it in the shop.Possibly chain the chassis to something solid and the try and pull the diff housing the opposite direction and see if you can measure any deflection in the mount?.

kevlarcorolla wrote: I would have to say it looks like the housing IS moving laterally,I watched the chassis end of the panhard and it sure looks like the heim is moving with load.Is the heim in single shear?,almost looks like its twisting the mount. Of course with the panhard out of level the housing will move laterally but with it looking like the chassis mount moving I think its worth trying to come up with a way to check it in the shop.Possibly chain the chassis to something solid and the try and pull the diff housing the opposite direction and see if you can measure any deflection in the mount?.

It could still be just the camera moving but I am going to take a close look at that mount before the next event

x2 on the frame mount.

Besides the heim being mounted in single shear, it is also off-plane to the triangular bracing and there is potential for twisting the entire piece of square tube that it is mounted to.

NOHOME wrote: x2 on the frame mount. Besides the heim being mounted in single shear, it is also off-plane to the triangular bracing and there is potential for twisting the entire piece of square tube that it is mounted to.

That mount is designed to be in single sheer and is for 800 hp dirt cars, so it should work in my application. I also don't know how I could make it double sheer and still have the adjustability I have now, not without ditching the whole thing and starting over.

I ran some laps around the Gimli road course and the car was huge fun. My autocross set-up makes the car feel pretty alive at 100 mph but it didn't do anything surprising or unexpected. And the couple of times I got on the gas too early and the back stepped out, it came back with a small correction.

I could definitely have set better lap times if I were more brave but I kept braking too early and waiting too long to get on the gas. Here's a video of a couple of laps: http://www.youtube.com/watch?v=e1oPVYK3VjY

I have new, wider front tires for Nationals and to avoid the chance of oversteer, I needed to change the front sway bar. I had a non-adjustable one on there before and I wanted an adjustable one but buying a custom made bar was out of my budget right now. I had some Porsche 911 torsion bars kicking around and it occurred to me that I could maybe use one as a sway bar. The beauty of using the 911 torsion bar is that there are a wide variety of sizes available and any one of them will slide right in if I need to change the stiffness.

There is very little real estate around my front suspension to mount a sway bar so instead of going under it, I went over it. Finding a mounting location for the drop links proved difficult. I landed up using a longer bolt for the pushrod mount and sliding the drop link over it. Here is a pic of the reinforced fender/rad mount with the sway bar mounted:

And the sway bar arms (painted pink)

And the drop link attached to the bar at the top and the rocker arm at the bottom.

The car will be for sale after Nationals (or before if the offer is right) so if interested, see me in Lincoln.

Hmm are you really sure that's gonna hold up? I'd test it early just in case.

You could also try linking the bellcranks with a threaded bar in a lateral seesaw arrangement to act as a sway bar, it would be lighter and easier to adjust. You'd probably have to fabricate new bellcranks though. Something like this:

Anyway I was waiting for an update to this build, you can bump it with a new title if you want to go into the new builds section.

GameboyRMH wrote: Hmm are you really sure that's gonna hold up? I'd test it early just in case. You could also try linking the bellcranks with a threaded bar in a lateral seesaw arrangement to act as a sway bar, it would be lighter and easier to adjust. You'd probably have to fabricate new bellcranks though. Something like this: Anyway I was waiting for an update to this build, you can bump it with a new title if you want to go into the new builds section.

The only thing I'm not sure about are the sway bar mounts. I have already jacked one front wheel up until the other side lifted off the ground and nothing broke. I plan on using an engine hoist to lift the entire front of the car by the sway bar mount to see if that breaks anything.

The new front tires are an inch taller than the Hoosiers and two inches taller than the Avons I ran at Springnationals. And with our local venue being smoother, I can run a lower ride height, which meant that some fender trimming was in order. I started by jacking up the opposite rear tire off the ground to compress the front then I marked the fender about 3/4" higher than the tire and trimmed it all around. I turned the tires full lock in both directions and I really hope I trimmed enough to keep the tires from getting cut.

You should bump the thread with a request to put it in the build section:

http://grassrootsmotorsports.com/forum/build-projects-and-project-cars/

Who do I ask for that?

Just post something like "bump, move to build section, same title"

Ok, I'll try it: bump, move to build section, same title

Tadaaaa! Moved.

Incredible power on tap here...

I had the first two events with the new front sway bar and wider front tires and the results were very, very positive. Lots of fun both days but Saturday went better for me. I was aggressive and the car responded well, setting decent times. On my first run, turn-in was amazing but the rear of the car was unstable so I stiffened the front sway bar. This cured the tailhappiness but there was less precise steering. Here's a video of my best Saturday run: http://www.youtube.com/watch?v=_w6tzYKv9lM

For Sunday, I put the front sway bar to the soft position again but lowered the rear panhard bar, which resulted in more rear grip. The car felt great with really good steering feel and the back end felt stable. The pivots were painfully slow and I was doing only 21 km/h around them. I was doing 115 km/h into the finish and knew from watching Run Group A that I would run out of stopping room fast. I hit the brakes hard, locking up the rears and spun it instantly, video here: http://www.youtube.com/watch?v=GEOH_s3blZQ

After that I was afraid to brake too hard for the pivots and the stop (only did 110 km/h on later runs) which resulted in poor times despite improvements in other areas. It was just poor driving, plain and simple. But, the car feels great and there are usually no pivots or stop boxes at Nationals so I should do ok. To illustrate the differences between our courses and Nationals courses, I couldn't get close to Jeff J at the beginning of the season but was 1.5 seconds quicker in Lincoln. Now at least I can match Jeff's times so I should do better next week. Also, due to understeer issues at Springnationals, it took 360 degrees of steering wheel rotation to negotiate the whole course, take a look at this video of my best run from today, I only need 180 degrees total if you exclude the pivots. http://www.youtube.com/watch?v=H0DD2vl4Rb8

loosecannon wrote: The car will be for sale after Nationals (or before if the offer is right) so if interested, see me in Lincoln.

Say it's not so! If it is, please say it's bacuse you have plans for a new improved updated version?

The Saturday run looks good. Why so slow around the pivots? Heavy steering effort?

Adrian_Thompson wrote:

loosecannon wrote: The car will be for sale after Nationals (or before if the offer is right) so if interested, see me in Lincoln.

Say it's not so! If it is, please say it's bacuse you have plans for a new improved updated version?

Sorry, I don't have the funds or time to develop the car so either I put a tarp over it for a few years or I let somebody else enjoy it. And it is a joy to drive. I have autocrossed many cars in 18 years and the Pink Panther is easily the biggest hoot.

We got rid of a lot of staff at Speedworld and my wife and I took over all their duties and hours, which leaves precious little time to tinker on a race car. I think we will do very well at Nats this year and I base this on our performance relative to locals here and at Springnationals vs now.

1967 MGB-GT race car

Built forSCCA Solo EMod class but is suitable for other road racing classes with small changes

2050 lbs

17.3” highCG

49%/51% F/R balance

Engine/Trans:

Ford 5.0 EFI bored .030 over

Hypereutecticpistons 9.25:1 compression ratio

ProComp Aluminum heads w/ 2.02/1.60 stainless valves 62cc chambers

Comp camsroller cam

Comp Camsroller steel rockers

Ported GT40intake

Tweecer engine programmer-change tune with the turn of a knob

Stainlesshigh flow headers

Road raceoil pan with baffles/scraper

Aluminum flywheel

265 wheelhp@5307 rpm

271 wheelft/lb@4839 rpm

T5 Trans with hydraulic TO bearing

Chassis/suspension

· 2”x4” frame rails · 1 ¾” DOM roll cage with mounts for door bars · Kirkey racing seat w/4 pt harness · Aluminum floor and interior panels · Pushrod/rocker suspension with variable motionratio-no need to swap springs, just move a bolt to increase/decrease stiffness · Double A-arm front suspension · 3 link rear suspension · 3 way adjustable shocks-hi/lo comp, rebound,pre-load · 6 way adjustable rear sway bar · 7 way adjustable front sway bar · Panhard bar with adjustable frame/diff mount · 5 gallon aluminum fuel cell · 4 piston aluminum Wilwood front brakes · 4 piston aluminum Strange rear brakes · Strange engineering rear diff housing · 31 mm Moser axles · Ford 9” center section with clutch LSD 3:1 ratio · Flat floor · Front adjustable splitter · Rear adjustable spoiler · Rear adjustable diffuser · Six 15” diameter and four 13” diameter Diamond racing wheels · 12.5x23.5x15 Avon A15 front tires, 14x23.5x15Avon A15 rear tires · Lexan windows · Quick release steering wheel · 1.5:1 and 2:1 steering quickeners included

$15,000 See the entire build of the car with pics/videos http://ultimatemgbbuild.blogspot.ca/ email marksawatsky at gmail dot com

Look at the difference in the cars attitude (and altitude) from before and now:

Now