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conebasher

Project E-Mod MGB-GT

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Built a rotissiere out of two 1000lb engine stands so that I could paint and work on the bottom of the car(and any future race cars ;) )

I've been thinking of using two engine stands as a rotisserie for a while. My concern was that the wheels were not spaced far enough apart for the thing to be stable. I guess it does work.Car looks great!

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I've been thinking of using two engine stands as a rotisserie for a while. My concern was that the wheels were not spaced far enough apart for the thing to be stable. I guess it does work.Car looks great!

I have the same concern and plan on widening the base before flipping the car, gotta get more steel, though.

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Tried bead rolling aluminium for the first time today, it stiffens up floppy sheet pretty nicely. Also filled holes in the bodywork left after removing the door locks, windshield wiper and trim.Posted Image

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I have the same concern and plan on widening the base before flipping the car' date=' gotta get more steel, though.[/quote']Looks great Mark, I am concerned that the CG of the car looks alot lower than your pivot points right now. It may be hard to turn. Is the height adjustable?

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Looks great Mark' date=' I am concerned that the CG of the car looks alot lower than your pivot points right now. It may be hard to turn. Is the height adjustable?[/quote']It is a lot lower. I attach the car to the rotissiere by a sliding tube and jack the car up to the height I need and tighten a bolt to lock the tube in place. I knew I wasn't going to flip the car with the engine in it so I just rocked the car back and forth a few times and took pictures. Once the engine is removed, I lift the car up so the CG matches the pivot height and the car will flip easily.

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Welded a panel where the sunroof used to be. It looks terrible because I couldn't get the contour of the panel to match the roof. I wish I had gone with my first thought which was to put a hinged aluminum flap over it and call it an escape hatch.Posted Image

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I removed the engine and front suspension and put the car on the spinner so I could weld up the motor mounts and cut out some excess metal from the old firewall. I also checked chassis stiffness by putting the car on stands at the 4 corners and jacking up one side (this was still when the engine and suspension were in). I could raise the front corner less than 1/4 inch before the back end would lift off the stand, is that good or bad?Posted ImagePosted ImagePosted ImagePosted Image

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Probably meaningless techno-geek stuff but I did some analysis today. I checked the torsional stiffness by putting the car on 3 stands (2 rear, 1 front corner) and hung a 100 lb weight 4 feet from the single stand and measured the amount of flex in the frame. Without the front crossmember bolted in=800 lb/ft per degree stiffness. With crossmember bolted in=1600 lb/ft per degree of twist. I still have another crossmember that gets bolted in so that number could go up. Also, I plotted the path of one of the rear wheels as it goes through it's projected travel and below is a pic of the passenger side path. Basically, as the suspension compresses(such as a hard left turn) the wheel moves up and slightly forward, causing the rear to steer in the same direction as the front-which is good for neutral handling. This is somewhat offset by the drivers side rear wheel drooping and also moving forward but there isn't as much weight on that tire so the outside one is the important one.Posted Image

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I got my rear tires mounted on wheels, the picture doesn't do the width justice, they are definitely what Jeff Kiesel calls "big boy tires".Posted ImagePosted Image

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No full view of the car with the wheels mounted? :D

I only have rear wheels and tires and no axles on the back to mount the wheels to. The axles have been ordered.

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Put in the mounts to hold my new Be Cool rad in. I had to cut off the front 4 inches of the frame horns in order to move the rad back, which meant a redesign of of the steering rack mount and shock mounts. The frame crossmember is now the steering rack mount and I built a strong bracket that ties the suspension crossmember and the frame crossmember together (I'll post pics tomorrow) to stiffen up the front end. I will also be changing the tubes that tie the rollcage to the frame.Posted ImagePosted Image

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The rain channels looked bad and were not aerodynamic so I removed them, and it was not easy.Here's the before:Posted ImageAnd after:Posted Image

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Cut away the rusty rockers to make way for side exit exhaust, I think they look good. These pipes are just a mock-up, mufflers to be decided on later.Posted ImagePosted Image

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The start of an aluminum firewall. Next time I build a racecar, more thought will be put into how the firewall will be because this one is very complicated and requires many pieces and complex angles.Posted Image

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Welded up some adjustable rocker arms for the suspension, with motion ratio adjustable from .65:1 to 1.55:1. I have serrated washers on order to hold the bolts in place but I may go to a threaded rod that will move the bolts back and forth and lock them in place. It makes a big difference where the pushrod and shock bolt on, at .65:1 the suspension doesn't budge and at 1.55:1 it almost bottoms out.Posted Image

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I modeled the pivot on the original motorcycle pieces but now looking at them I realize that the pushrod should be pushing at a 90 degree angle to the direction of the shocks-guess I'm breaking out the grinder :(

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I modeled the pivot on the original motorcycle pieces but now looking at them I realize that the pushrod should be pushing at a 90 degree angle to the direction of the shocks-guess I'm breaking out the grinder :(

Looks pretty close to 90 in that pic. No?

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Looks pretty close to 90 in that pic. No?

No actually. The pushrod is 90 degrees to the shock but you have to look at the line between the bolt that holds the pushrod to the pivot point vs the line from the bolt that holds the shock to the pivot point. If you imagine the direction that the pushrod would travel through, you see that at some point (as little as 2 inches of travel) the pushrod would try to force the bolt out of the slot-not good.

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I mounted the smallest 55 amp alternator I have ever seen (5.7 lbs):Posted ImageAnd remade the rocker arms so the pushrods are moving at a 90 degree angle to the shocks, and uses holes instead of slots to ensure the bolts stay where they are supposed to be:Posted Image

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Super jealous of that alternator, and those rockers look really good Mark! It looks like you are super close to a 90 degree angle between push-rod and rocker which will make tuning your suspension so much easier!

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Thanks to Dan Lipperini Jr at www.racelabz.com for sending me a beautiful towhook to replace my ratty old one:Posted Image

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It was a productive day today. I got the radiator mounts made and the top plate is made from the aluminum skid plate off a Suburban 4x4:Posted ImageAlso installed the fuel filler for the Jaz fuel cell:Posted ImageAnd made new front shock mounts that also act as a brace for the crossmember and weighs less than the old shock mounts:Posted ImagePosted Image

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And made new front shock mounts that also act as a brace for the crossmember and weighs less than the old shock mounts:Posted Image

I don't follow. How are those acting as a brace?Also... Wow, you really love allen bolts.

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I don't follow. How are those acting as a brace?Also... Wow' date=' you really love allen bolts.[/quote']The crossmember goes under the frame then up on each side. Look at the bottom pic and you see that I have bolted the shock mount tube to the upright portion of the crossmember, stiffening it a little bit. If I attach small braces from the tube to the frame, it will be even better.

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My 9 lb Braille battery from www.fasttoys.net, mounted in the passenger side front wheelwell. I considered putting it in the back of the car but the weight of the cables would equal the batteries plus the amp drop might mean I have to go to a bigger battery. And, yes, I will be putting a protective plate in the front to keep rocks from hitting it.Posted ImageOne advantage of a 12" driveshaft is that only one driveshaft loop is required:Posted Image

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Is that dinky little 9 lb batt gonna be able to turn over that big V12?I know that even my smallish Honda battery can't crank big V8 engines...

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Is that dinky little 9 lb batt gonna be able to turn over that big V12?I know that even my smallish Honda battery can't crank big V8 engines...

It's rated to start V8 race engines so I imagine a 5.3 Litre low compression V12 will be no trouble. If it is, I will put an 11 lb battery in.

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I am sorry to tell you this but you will be remaking the rockers again before you will be satisfied. The way you currently have them as the suspension compresses it will gradually become a falling rate linkage. You can fix this 2 ways or use a combination of both. You can shorten the pushrod and make it so the rocker never moves to that situation or leave the pushrod alone and reduce the rocker angle to less than 90 degrees. Actually a third option also exists, you could drop the inboard mounting point also. Bonus on all of this is that with steel rockers you are not out anything other than your time. ( steel is still reasonably cheap).I am sorry that my first post on your thread is a bit to the negative . I have been following the build and overall I am very impressed. As a builder of wierd stuff myself input is appreciated but not allways heeded.

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