BTTF Time Machine Build Questions - Ask Me Anything

[Timebender]

Hey Mark,
I have a question about the vents - which I did as a separate post but thought I’d ask here as well.
This is purely going off Gary Weaver’s DXF file, because I noticed there are two different lengths for the vents in his file - each one being segmented- but there’s a long one and a short one - so am I to guess that one vent is longer than the other where it goes more towards the cabin, or does each vent have a long and short side?

[Mark D]

Hey Mark,
I have a question about the vents - which I did as a separate post but thought I’d ask here as well.
This is purely going off Gary Weaver’s DXF file, because I noticed there are two different lengths for the vents in his file - each one being segmented- but there’s a long one and a short one - so am I to guess that one vent is longer than the other where it goes more towards the cabin, or does each vent have a long and short side?

The vents are symmetrical down the centerline of the car. I don't have any of weaver's files so I'm not sure which pieces exactly you're talking about exactly but:

The large side sheets of the upper section of the vents (the big ones that mount to the engine cover) should have the same overall dimensions inside and outside, left and right. There are differences in the placements of the holes for mounting the various hoses, etc but these big pieces should be the same size.

The lower sections of the vents that wrap around the fascia and tail lights are made up of different sized pieces that are assembled in mirror image for the LH and RH side. The lower vent weldments extend out the same distance off the upper vent sections and and are "square" to the vent, but the odd shaped cutouts that face the fascia/tail lights are different for each of the three vertical pieces. This is due to the curvature of the fascia and tail lights. The outside vertical pieces are larger and the inside pieces are slightly smaller. The middle vertical piece is about half way between the inside and outside in size. The bottom plate of the lower vent section weldment is a trapezoid shape and not rectangular.

I don't know what kind of information weaver provides about how the parts are supposed to overlap either, but it's important that you mock everything up first and make sure you have the corner overlaps correct. You need to be sure of how the parts sit on top of each other, otherwise you'll end up with welded assemblies 1/4" too wide or too narrow. I'm not sure how his parts are designed if you are supposed to sandwich the tops of the vents between the side plates or lay the top piece on top of the the sides.

When we build vents we use a special jig that is designed to hold all the parts together in the correct orientation. This makes it more obvious how the overlaps are supposed to go and also holds all the angles square and keeps the overall dimensions in spec.

[Timebender]

Thanks Mark, that helps a heap!

[Mike1830]

Here is a foam board mock up of Garys dimensions. Sorry if some of the pics are rotated incorrectly

[petriomelony]

Here is a foam board mock up of Garys dimensions. Sorry if some of the pics are rotated incorrectly

Interesting. Perhaps he didn't get around to updating that part of the file, as it doesn't match his A-Car reference photos, and it looks a bit funny sitting on the fascia like that.

This photo, for example, shows the rear/lower part of the vent quite different in shape to match the rear fascia of the car:

A Car Vent Reference.jpg Source: Gary's Uploads to FB

Or perhaps he gets it cut as a larger piece and then customizes it further afterwards. He did say in a previous post that often times he didn't even go from drawings, he just mocked it up or had jigs or something.

In any case, I wouldn't hesitate to deviate from the drawing to suit other information as you find it. In my opinion, I would try to avoid contact with the fascia since it's painted, and try to have all of the load of the vents resting on the engine cover sheet. Perhaps Mark can elaborate on whether the vents should touch the fascia or not.

[Mike1830]

Ya i noticed that as well. I have a bunch of reference photos of the cut out so the lower part will wrap the fascia. I just didnt cut it out yet.

Sent from my SAMSUNG-SM-G930A using Tapatalk

[Mark D]

Sometime in the mid 1990's the the vents on the A-car were modified by the guys in the transportation garage at Universal Studios. The lower vent sections that normally wrap around the fascia to be flush with the tail lights were cut and welded to look like what you see in that reference photo. The point of the modification was to allow the engine cover to be raised and lowered without having to remove the lower half of each vent. Normally this requires removing a few dozen button head screws with an allen wrench and is time consuming.

An old ref photo of the A car in 1986 or so prior to modifications.




And the restored A car with the vents fixed to look as they originally did:


The design intent of the vents are to hug as tightly as possible to the fascia to make it look as though the vents are actually cutting through the car. For them to be "real" and function, big chunks of the fascia and tail lights are supposed to appear as though they were chopped out to allow the vents to pass through.

[Mike1830]

Hi Mark,

Are you able to send me the correct part numbers/ dimensions of the zero boxes that were used all over the car. I have 3D models of them but would prefer not to 3D print them. Rather have the real deal if they still make them

[Mike1830]

Sometime in the mid 1990's the the vents on the A-car were modified by the guys in the transportation garage at Universal Studios. The lower vent sections that normally wrap around the fascia to be flush with the tail lights were cut and welded to look like what you see in that reference photo. The point of the modification was to allow the engine cover to be raised and lowered without having to remove the lower half of each vent. Normally this requires removing a few dozen button head screws with an allen wrench and is time consuming.

An old ref photo of the A car in 1986 or so prior to modifications.




And the restored A car with the vents fixed to look as they originally did:


The design intent of the vents are to hug as tightly as possible to the fascia to make it look as though the vents are actually cutting through the car. For them to be "real" and function, big chunks of the fascia and tail lights are supposed to appear as though they were chopped out to allow the vents to pass through.

Was the original hoodlatch functional or did they rely on the weight of the props to keep the engine cover closed?

[Mark D]

So it looks like on the files that weaver provides there is no notch in any of the lower vent plates where they are supposed to contour to the fascia. You are left to your own devices to figure out how much to chop out (Green) so that you can push the vent forward into the correct location. The rectangular cutout in the big forward side plate should line up with the fascia (yellow dashed lines).