Heater Box (HVAC Box) Removal Question

#1

We’ve got a '90 E30 we’re tearing apart for a cage for SE30. We’d like to take the heater box out to do away with all the HVAC in preparation for a cross bar through the dash. We’ve got pretty much the whole interior shedded aside from the box and carpet. We’d like to keep the piece intact, but all I am seeing on the web are people smashing them to pieces. I can best describe the hinderence as a washer with two cam-like tabs opposite each other to “lock” the hex-headed bolt in place and prevent any movement (or to get a socket on for that matter). So obviously there are nuts elsewhere that need to be taken off; where are these and how do you get to them??

Here’s a quick, yet terrible picture of what we are dealing with. You can make out one of the “tabs” on the closest face of the hex head. There is another mirrored on the other side of the head and another set further down the firewall (as well as two more sets on the other side of the box - left of this picture).

Thanks in advance for your swift response.

-Tyler

#2

There may well not be nuts that you can get to on the other side of those bolts. Recall the bolts that hold the steering column to it’s support under the dash. They are a “tamper resistant” design. You may well be looking at a different kind of tamper resistant design that might require a special socket to remove. If you really want to take that piece off intact you might try to hit the tamper tabs with a dremel.

Brute force. That’d be my solution. There comes a time when a person just looses patience with trying to finesse something. That’s brute force time. If the SOB gets ruined in the process and requires a credit card to fix, at least you had the satisfaction of bashing the shit out of it.

#3

In all honestly, brute force is my solution as well. Only issue is that this is a friend’s car that we are helping out with. I didn’t want to be “that guy”. I didn’t think to hit it with a Dremel…space for the tool could be a concern, too.

Looking at it, I don’t see how accessing the nuts (if there are any) is possible either. This is one of the cleanest E30s I’ve seen, so I also hate beating good parts up. However, the only info/videos I have seen on the subject show people tearing the box to shreds.

#4

First of all it isn’t necessary (or desirable) to remove the HVAC box to install a dash bar. The bar can be made and installed to fit around the HVAC box. The reason to keep the HVAC box is for the defroster. You’ll have to modify the ducts that feed the vents in the dash, but a defroster on a rainy day is a valuable thing. Any good cage make will know how to accomplish this.

#5

If you remove the two little recirc motors from the HVAC box, then that makes a good place for the dash bar.

#6

I don’t remember the details of taking mine out after the core poped but those tabs look pretty wimpy. Pry it away with a scredriver or just put a wrench on it and let the bolt head move it out of the way.

#7

Remove the panel directly behind the intake manifold on the firewall. That’ll give you access to the nuts that hold it all together. I’ll try to get some photos up tonight.

#8

Here’s the photos…

We fabricated a simple panel to block off the hole…

#9

is it required to block off that hole since it does not actually go into the engine bay, but rather it links to the wants below the windshield.

#10

Leave the sheetmetal in place on the engine bay side of the hole. Don’t worry about the passenger compartment side.

#11

FWIW my dash bar is well above the HVAC box. A little cutting on the central vent fits all the basic air handlers back into place during dash reinstall but the instrument cluster gets pushed forward a couple inches. The benefit is keeping the factory defroster in place.

#12

I don’t think it’s required, but I figured it was better to keep out whatever might come through there.

#13

Thanks for everyone’s response. We ended up going in through the engine compartment (coincidentally as Matt had suggested). Been slammed with work and haven’t had a chance to hop on here. An electric defroster is permitted, so we’ll be using one of those. We wanted a completely straight cross bar along with the shedded weight.

#14

I don’t think it’s required, but I figured it was better to keep out whatever might come through there.[/quote]
Keep in mind how the rules work. Unless the rules say you can screw with something, you can’t. Therefore the sheetmetal on the engine bay side of that hole should remain. If yanking the HVAC exposes a big hole that you don’t like, put a little of the HVAC back. But patching the hole with a piece of sheetmetal or sheetplastic wouldn’t be my first idea.

No ones really going to care if or how you plug that hole, but it’s important to know how the rules work. When one is considering a non-OEM solution they should pause and consider how their idea fits within the rules.

#15

[quote=“Ranger” post=65270]
Keep in mind how the rules work. Unless the rules say you can screw with something, you can’t. Therefore the sheetmetal on the engine bay side of that hole should remain. If yanking the HVAC exposes a big hole that you don’t like, put a little of the HVAC back. But patching the hole with a piece of sheetmetal or sheetplastic wouldn’t be my first idea.

No ones really going to care if or how you plug that hole, but it’s important to know how the rules work. When one is considering a non-OEM solution they should pause and consider how their idea fits within the rules.[/quote]

Oh yeah, the engine bay side panel absolutely should be, and was, replaced.

The large inner hole is left after removal of the AC/heater box, which is completely within the rules. The only thing I did beyond that is to cover the hole with a steel panel because there is absolutely no practical way to “put a little of the HVAC back”. It’s sort of all or nothing with the big heavy box.

The reason for the filler is to keep whatever junk that may come thru the cowl vents (leaves, rain, tire chunks, flames, etc.) from entering the passenger compartment.

If you’re suggesting that it’s outside of the letter of the rules to add the filler panel, I probably agree. On the other hand, I could probably argue from a safety standpoint that it actually should be required after HVAC removal for the reasons I mentioned above.

Is it worth submitting a rule change request? The only way it’ll impact me is if it’s denied and someone protests my panel. For the people who have pulled the HVAC and left the hole it’ll require some work if it gets approved.

#16

Cut the plastic box right at the squirrel cage and put it back in the hole, leave power to it and remount the fan switch wherever. On the hot days on pre grid you can get some ventilation, works great! Zoom in on the pic and you can see the cut HVAC box. I can get detailed pics next week if you want.

[attachment=1831]IMG_3628.JPG[/attachment]

#17

I left the inside hole open. I hope that any protest for covering the hole would be laughed at.