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Last Post 13 Mar 2017 09:33 AM by  loosecannon
EMod MGB-GT build thread
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tsdracing78
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13 Sep 2010 06:09 PM

at the risk of sounding geeky this car already looks sexy as hell please keep posting looks great

loosecannon
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14 Sep 2010 06:20 PM

Got the 4 link rear suspension welded in, these pics were taken before I welded in reinforcement bars. I don't have an axle yet so some exhaust tube stands in it's place:
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Don't know why it hangs so low but as per the directions, the bars are level and can be adjusted up or down based on what I want the car to do:
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Transmission crossmember is in and had to be notched to make the trans level:
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Dash bar:
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Top cross bar is in:
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I mocked up the pedal location and now that I moved the engine back so far, I ran out of room. I have already started making a pedal box that lowers the pedals 4 inches and gives me some room, I'll get picks of that when it's done:
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gavin
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14 Sep 2010 07:36 PM

the question is ......can you make that V12 sound like this?

http://www.youtube.com/watch?v=M9I7GWllPFY

Gavin

loosecannon
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14 Sep 2010 08:48 PM
gavin wrote:

the question is ......can you make that V12 sound like this?

http://www.youtube.com/watch?v=M9I7GWllPFY

Gavin

I've had the engine running and I think it actually sounds meaner than that. I will be putting headers on it and expect it to really howl ;)

loosecannon
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15 Sep 2010 04:14 PM
The floor framework before the sheet metal is attached (3/4" super thin wall square tube):
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The dropped pedal box:
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With the drivers side sheet metal in:
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The pedal box is still tight (no room for dead pedal) but at least it's useable now.
loosecannon
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16 Sep 2010 04:05 PM
I didn't like the location of the shifter so I came up with this solution. I wasn't sure it was going to work but it actually works awesome :)
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Passenger floor is in:
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loosecannon
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17 Sep 2010 06:41 PM
Too busy to do any work on the car but ONE of my front shocks arrived. It's an Ohlins sportbike rear shock and has high/low speed compression, rebound, pre-load and height settings. If you look at the linkage that was included(attached to the bottom of the shock in the picture) it actually bolts onto the top of the shock as well and my plan is to use it as a rocker arm for a pushrod front suspension.
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loosecannon
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20 Sep 2010 12:38 PM
I wanted to get an idea of the weight of the car so I put everything I had on it in approximately the position it would be in and put simulated weight on it for the parts I don't have yet. The bad news is that it's too heavy by 188 lbs but the good news is that the weight balance is 54% Front, 46% Rear. I can still cut a bunch of weight out of the hood/fenders/doors/interior and crossmember plus the cast iron exhaust manifolds are heavier than the headers but it looks like the car will be a little heavy. I'll be going at it with a hole saw and plasma cutter this week.
dglong
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20 Sep 2010 01:49 PM

Welcome to E Mod. I'm pretty sure it will be the first V12 in the class.

Del Long

47CP
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20 Sep 2010 02:39 PM

You are only going to be #188lbs over including the driver? That is very impressive. BTW, I don't have an exact number but there ended up being #75 of misc fasteners in my car (rivets, bolts, tabs, hidden illegal modifications, etc)

This thing is bad ass. Welcome to the class and I can't wait to see it.

DaveW

loosecannon
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20 Sep 2010 03:22 PM
47CP wrote:

You are only going to be #188lbs over including the driver? That is very impressive. BTW, I don't have an exact number but there ended up being #75 of misc fasteners in my car (rivets, bolts, tabs, hidden illegal modifications, etc)

This thing is bad ass. Welcome to the class and I can't wait to see it.

DaveW

Thanks for the welcome Del and Dave :) Yeh, the car is currently just over the class minumum (1863 lbs) without me in it. It's encouraging that you got that much weight out of your car with little stuff. I have lots and lots of places I can shave weight off. I will be swiss cheesing the crossmember, parts of the frame and inner body panels, cutting out the inner door structure and trimming the fender and hood structures. I'll be happy if I keep it below 1950 lbs with me in it. The V12 should move it along smartly and sound like nothing else at Nats

loosecannon
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21 Sep 2010 03:46 PM
Spent today cutting metal out of some places and welding metal into other places. Note the side frame rails:
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And the rear frame rails:
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And I welded in these brackets from the A pillar to the roll cage:
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loosecannon
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23 Sep 2010 04:17 PM

More time spent with the plasma cutter. I am saving all pieces cut out and all this work has only resulted in (estimated) 25 lbs cut out :(
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The stock front suspension:
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And the start of the new suspension. I still need to sort out the shock location and have several different upper mounts which alter camber gain. This is the taller mount which has zero camber gain:
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47CP
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23 Sep 2010 06:47 PM

How much angle is on those upper arms? It looks like very little and speaking from expensive experience, you should not underestimate the loads here. You really want/need the arms as wide as possible that still allows you to turn the wheels (assuming the ball joints are inside the wheels). The stock arm has a pretty strong "H" section that you appear to have not recreated.

DaveW

[broken upper and lower arms on my suspension designs]

loosecannon
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23 Sep 2010 07:46 PM
47CP wrote:

How much angle is on those upper arms? It looks like very little and speaking from expensive experience, you should not underestimate the loads here. You really want/need the arms as wide as possible that still allows you to turn the wheels (assuming the ball joints are inside the wheels). The stock arm has a pretty strong "H" section that you appear to have not recreated.

DaveW

[broken upper and lower arms on my suspension designs]

The top arms are actually farther apart than the stock ones and I haven't added the brace yet because I haven't sorted the pushrod for the shock yet and don't want to weld something in just to cut it out later. I am thinking about widening the top arms to make more room for the shock and pushrod but I run smack into the tube that goes from the roll cage down to the frame.

loosecannon
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24 Sep 2010 11:01 AM

I widened the top arm mounting points by 3" over the factory width to give the suspension more stability, and lowered them to increase camber gain. Now I have approximately .9 degrees for every inch of wheel travel. I still have to change the pushrod to an adjustable rod with heim joints and have to add a brace to the top arms.
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loosecannon
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24 Sep 2010 03:21 PM
Suspension update: I jacked up the suspension to see how the shock compresses and it didn't budge. I thought maybe the pivot was binding but that wasn't a problem. I had assumed the pivot had a 1:1 ratio (1 inch of suspension travel equaled 1 inch of shock compression) but I was wrong. I measured the rocker mechanism(the aluminum triangle thingy) and it was 3.25" from the pivot to the pushrod and 4" from the pivot to the shock. I flipped it around and problem solved, the suspension moves very nicely and compresses the shock as it should. You gotta love the complexities of suspension ;)
47CP
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24 Sep 2010 06:48 PM

I am no ME,but that upper arm is giving me headaches. Your loads won't be as high as they were in my CP car, but I have a stack of failed upper arm designs from some similiar issues that you are creating.

The attachment from the upper ball joint/king pin to the arms is putting load on things in all the wrong ways. Is there a way to adapt a C shaped mount to the splindle, allowing you to rotate the rod ends horizontally? Perhaps a stock car style shock mount would work. This would remove the load from the bolt shafts as it is now and also load the rod end properly (not that a lot of rod ends aren't loaded the same way). This would also allow the arms to go out wider in the back becuase IMO you do not have enough triangulation angle.

Looks great and great progress. Rocker arms really help with packaging.

DaveW

loosecannon
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24 Sep 2010 08:50 PM
47CP wrote:

I am no ME,but that upper arm is giving me headaches. Your loads won't be as high as they were in my CP car, but I have a stack of failed upper arm designs from some similiar issues that you are creating.

The attachment from the upper ball joint/king pin to the arms is putting load on things in all the wrong ways. Is there a way to adapt a C shaped mount to the splindle, allowing you to rotate the rod ends horizontally? Perhaps a stock car style shock mount would work. This would remove the load from the bolt shafts as it is now and also load the rod end properly (not that a lot of rod ends aren't loaded the same way). This would also allow the arms to go out wider in the back becuase IMO you do not have enough triangulation angle.

Looks great and great progress. Rocker arms really help with packaging.

DaveW

I think I understand what you're saying but I don't see how what I've done is different than the stock MGB suspension. Take a look at the pic of the stock suspension, a bolt goes through the upper and lower kingpin and the arms rotate on them. I have copied all that except am using a longer bolt to allow the heim joints to attach and now the rotation occurs in the heim joint instead of the kingpin bushing. What do you think is going to fail? Keep in mind that I still have to add an X brace to the upper arms.

47CP
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25 Sep 2010 04:20 AM
loosecannon wrote:
47CP wrote:

I am no ME,but that upper arm is giving me headaches. Your loads won't be as high as they were in my CP car, but I have a stack of failed upper arm designs from some similar issues that you are creating.

The attachment from the upper ball joint/king pin to the arms is putting load on things in all the wrong ways. Is there a way to adapt a C shaped mount to the spindle, allowing you to rotate the rod ends horizontally? Perhaps a stock car style shock mount would work. This would remove the load from the bolt shafts as it is now and also load the rod end properly (not that a lot of rod ends aren't loaded the same way). This would also allow the arms to go out wider in the back because IMO you do not have enough triangulation angle.

Looks great and great progress. Rocker arms really help with packaging.

DaveW

I think I understand what you're saying but I don't see how what I've done is different than the stock MGB suspension. Take a look at the pic of the stock suspension, a bolt goes through the upper and lower kingpin and the arms rotate on them. I have copied all that except am using a longer bolt to allow the heim joints to attach and now the rotation occurs in the heim joint instead of the kingpin bushing. What do you think is going to fail? Keep in mind that I still have to add an X brace to the upper arms.

The stock arm appears to be a pretty strong forging/casting that would put a lot of load on that center brace under braking. EG, under braking the entire upper arm will try to rotate and pull against the frame mounts, in a path mostly perpendicular to the direction of travel.

You won't be able to replicate that strength in that same direction with your arms, so you need more triangulation, IMO.

I barely see enough room for an x-brace in there, but after you install that, I see the gold arms themselves failing and bending in two. The large bolt through the balljoint/kingpin may be large enough to overcome it, but I also see weakness in this area as you are now pushing on it at an angle instead of straight. Finally, the angle load on the heims is trying to push the ball out of the body, which could cause a failure but will more likely just cause accelerated wear.

Copying stock may not be good enough, and I don't think you built something as strong as stock. It was designed for a 13x4.5 bias tire and drum brakes presumably and you are going to put 10" wide slicks and 4 piston disk brakes. You are building a car capable of 1.5g lateral acceleration and 1.3+ in braking.

I hope this comes across as helpful, it is certainly intended to. I am not picking on you, just giving my opinions. I have built 3 suspensions and have learned some stuff the hard way and one of those lessons is never underestimate the loads put into the upper a-arm in autocrossing.

HTH, IMO, YMMV,

DaveW

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