SCCA EMod MGB GT V12 Build

loosecannon wrote: I will not be moving it 8" back because it puts the driveshaft into too sharp an angle

Remember - nothing says that the engine HAS to sit square in the chassis. If you angle the engine, you cut the driveshaft angle by that amount.

DILYSI Dave wrote:

loosecannon wrote: I will not be moving it 8" back because it puts the driveshaft into too sharp an angle

Remember - nothing says that the engine HAS to sit square in the chassis. If you angle the engine, you cut the driveshaft angle by that amount.

Yes, I thought of that but seem to remember reading something about problems with doing that. But, if I can do that, it certainly lets me move the engine back farther.

I can't think of any problems with a caddywompus engine, but maybe the peanut gallery has some thoughts.

I can't think of any problems that would cause...once it fits it should be fine. Angling an engine forward/back or leaned left-right could cause lubrication problems, or a massive change from lateral to longitudinal could as well, but a little left/right rotation should be fine.

Any issues with uneven drive shaft U-joint angle front and rear?

Try to angle it so that the UJ angles at each end of the driveshaft are about the same.
(easy to say, maybe not so easy to do ;)

erohslc wrote: Try to angle it so that the UJ angles at each end of the driveshaft are about the same. (easy to say, maybe not so easy to do ;)

That's the problem, the engine will be pointing at the diff so the u-joint at the tranny will have little angle and the one at the diff will have much more. The only way they can have the same angle is if the crankshaft is 90 degrees to the rear axle, unless I misunderstand it

Yeah there's no way around that. The further back you go the sharper the angle at the diff. Angling the engine will only solve 1/2 of the sharp angles.

What about dealing with the angles using a double cardan or CV joint?

Or if you really wanted to blow $$ there's always offsetting the diff itself. I can't see an easy way to do that with your application other than custom axles and axle tubes off the housing though.

I'm sure you can angle the engine tranmsission off square a couple degrees without huge problems. Leaf-sprung vehicles have a pinion angle that's all over the place, and they work fine. Whether you make that angularity in the vertical or horizontal plane shouldn't matter.

If it wears out u-joints quickly - who cares; racecar.

So the tailshaft points at the diff UJ?
I assume that your driveshaft is rather short?
Perfect!
Now swing the tailshaft just a bit further, ie the motor/trans is at even more of an angle vs chassis centerline.
The tailshaft UJ angle will increase, and the Diff UJ angle will decrease.
Shouldn't take more than an inch or so.
FYI, it turns out that UJ running at a slight angle have better longevity than those which are exactly aligned.
When the needles in the roller 'rock', it promotes lubricant circulation, and avoids flat spotting the contact points.twixt' needle and race.

I began the process of fabricating new front suspension arms and ran into a problem. The Jaguar uprights incorporate the lower ball joint instead of the normal way of the ball joint being in the control arm. While thinking about this I noticed that the uprights run very close to the 15" wheel I am using and I realized that running a 13" wheel or even a wider 15" wheel would never be possible. I decided to look at using a Mustang II upright instead. Here is a pic og the Jaguar upright

I chose the Mustang II upright because they have been used by hot rodders for years and come in standard, 1" dropped spindle and 2" dropped spindle. And the Performance Trends program I am using happens to have the Mustang II suspension as an example. I plugged the 2" dropped spindle version into the program and started designing a suspension around that. The geometry landed up being superior to anything I could make with the Jaguar upright. The roll center is 1.58" and at 1.5 degree roll, only moves .01". I have -.76 degrees camber gain and anti-dive is 25%-in my opinion these are perfect for autocross.

Because I had new uprights, I would need new brakes and Wilwood had just the answer. A lightweight drag racing brake system that has plenty of braking for an 1850 lb autocross car that doesn't use a lot of brakes. They will save me 40+ lbs over the Jaguar set-up. Here's a pic:

Just a question, are those brakes going to end your track days?

DaewooOfDeath wrote: Just a question, are those brakes going to end your track days?

No idea, but my idea to make the car suitable for track days also made it far too heavy for autocross. If I want to run at the class minimum weight, I have to give up the big brakes, big wheels, big radiator and anything else not absolutely necessary to run through cones as quickly as possible for 60 seconds at a time.

Just wanted to point out, today I wanted to look up the SCCA Emod rules and I typed "SCCA Emod" into Google, and the first suggestion was "SCCA Emod MGB V12." This build is that popular

GameboyRMH wrote: Just wanted to point out, today I wanted to look up the SCCA Emod rules and I typed "SCCA Emod" into Google, and the first suggestion was "SCCA Emod MGB V12." This build is that popular

That's awesome, I guess I should take the build seriously then?

loosecannon wrote:

GameboyRMH wrote: Just wanted to point out, today I wanted to look up the SCCA Emod rules and I typed "SCCA Emod" into Google, and the first suggestion was "SCCA Emod MGB V12." This build is that popular

That's awesome, I guess I should take the build seriously then?

Except it isn't a V12 anymore or a MGB GT. Sad panda is sad.... It just seems like it is just another tube-frame car with some semblance of a body flung on it. Don't get me wrong, I admire the work and understand why you're going the direction you're going, just preferred the old section of the build when it was a highly modified BL car powered by the largest BL motor of the time.

turboswede wrote:

loosecannon wrote:

GameboyRMH wrote: Just wanted to point out, today I wanted to look up the SCCA Emod rules and I typed "SCCA Emod" into Google, and the first suggestion was "SCCA Emod MGB V12." This build is that popular

That's awesome, I guess I should take the build seriously then?

Except it isn't a V12 anymore or a MGB GT. Sad panda is sad.... It just seems like it is just another tube-frame car with some semblance of a body flung on it. Don't get me wrong, I admire the work and understand why you're going the direction you're going, just preferred the old section of the build when it was a highly modified BL car powered by the largest BL motor of the time.

That is definitely what made the build cool in the beginning but viewed as a whole, isn't it interesting seeing how far I have to go to build a competitive car?

I think it's interesting that this car has been made into a completely different car 2 or 3 times by now and there isn't much of the original left It's the build thread that keeps on giving even after the car is finished!

turboswede wrote: Except it isn't a V12 anymore or a MGB GT. Sad panda is sad.... It just seems like it is just another tube-frame car with some semblance of a body flung on it. Don't get me wrong, I admire the work and understand why you're going the direction you're going, just preferred the old section of the build when it was a highly modified BL car powered by the largest BL motor of the time.

I think it's awesome, it's 10 years and 3 or 4 major iterations of one car compressed into a 2 year time line.

It's been a long time since I updated this because I'm still waiting for the frame to be analyzed in CAD before I start welding metal. I put the new brakes and uprights together and weighed them and that's when I realized that the shipper sent the undrilled rotors when I ordered the drilled versions. Still, take a look at the weight difference between the old and the new:

So amazing!

Know what this is? It's the start of a super strong, light frame for the MGB. It's the perimeter frame and the rear lower suspension mounts are on the right and the lower front control arms will bolt to the pieces sticking forward on the left. I thought I had enough tubing left over from the last frame to make the main roll hoop, but I made a discovery.

The SCCA rule book calls for either 1.5"x.120" wall thickness DOM or 1.75x.095" wall thickness DOM tubing for the main roll hoop. I grabbed the last piece of 1.75" DOM I had left and it was long enough for the hoop but before bending it, I decided to check it's wall thickness-it was .120" thick, not .095" like it's supposed to be! That means for every foot of tubing I used, the car was .5 lbs heavier than it needed to be. Just the roll hoop would be 5 lbs too heavy. I have the proper stuff on order and can't wait to get going on the roll cage.

Yessir, tubing wall thickness is a big deal. That's why I tend to use 1.750 x .095 wall on bars and cages, it meets all the regs and is considerably lighter than the 1.625 x .120 wall that can be used in its place. It's easy to be 30 pounds heavier on a cage by using the thick wall tubing!

The computer model says the frame will be well under the 300 lb weight goal I had set for it but I'm waiting until the car is ready to drive and 1850 lbs before I get excited.

The CAD work has all been done for the suspension and frame. The front suspension has fantastic numbers and the frame should weigh 300 lbs and have a torsional stiffness of 11,000 lbs/degree. I wish I had pictures to show you but as soon as the steel arrives, it will go together quickly and you'll see the real thing. BTW, I have a real good idea of the weights of all the components and the car should come in at 1850 lbs with driver.