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Heater Box
Part 3 - New Foam Kit

May 9, 2008

When I first started down the path of rebuilding my heater box, the plan was to replace the foam with stuff from the home center but I wasn't too happy with their selection so I ended up doing some research that turned up nothing useful to me. About a month ago, I ended up looking on eBay for the next part I "need" and I noticed a bunch of AMC gaskets marked "DMT". As it turns out, "DMT" means Detroit Muscle Technologies which is a company that makes these types of parts for a lot of Chrysler cars and is looking to get into AMC (they do have some Javelin and AMX stuff already). They were eager to make my gaskets for me so I took a lot of measurements, did some drawings, consulted a mechanical engineer about them (seriously, thanks dad!), and sent everything off.

Last night (May 8th), the gaskets were waiting for me. The picture below shows most of what arrived. There is one part I'm not showing on purpose now, but I will add a picture of it when I get the final version. Also, keep in mind that this is the first take based on some pretty ratty (or non-existent) samples so a few things will end up tweaked a little in final form.

Here is what the parts are:

1. Defroster duct extension to defrost duct seal.
2. Blower motor mounting stud grommets (the hole in the middle is a hair small in this set).
3. Heat/defrost blend door insulation.
4. Heat/defrost blend door bumper.
5. Air door bumper.
6. Air door insulation.
7. Heater core end gaskets (this part isn't thick enough and is being changed to the proper thickness).
8. Heater core tube seal.
9. Heat core front gasket.

Part H is for 67 and older cars with two 5/8" heater core nipples. A suitable (albeit incorrectly shaped) seal for 68 and up cars is available from most AMC suppliers.

The finalized kits will have three additional gaskets in them. There is a gasket that goes between the blower motor and it's mounting plate (this is currently available from other vendors but off slightly), a gasket that goes between motor mounting plate and heater box (the one currently available is the wrong shape for Americans and made of the wrong material), and the heater box to cowl seal.

The cool part about this is that most of the parts fit first generation Javelin and AMX models. Parts A and B are American specific for sure, C-F are a maybe - the part book doesn't list these since the heater box would have been replaced as an assembly, and some of them even fit all models of that era (G -- as noted above, H, I, and the blower motor to mounting plate gasket).

DMT is also doing a correct wiper motor mounting gasket (the one currently available is too thick and missing some details) and a few other parts. More on those as they are available.

Update: May 29, 2008

The last of the parts I was waiting on showed up today. The large rectangular part is the heater core to cowl gasket, the small round part is the blower motor to heater plate gasket (more on that below), the tear drop shaped part is for the blower motor plate to heater box (this needs trimmed so its round), and the small rectangular parts are the heater core end gaskets.

Here is one of the parts that DMT improved over the previously available part (blower motor to mounting plate gasket). The part on the left is the DMT part and the one on the right is made by REM. Both parts will fit and work but notice the different in the holes? The reason the DMT part has four holes is that the same gasket was used for both A/C and non-A/C cars and each motor has different mounting stud spacing. The DMT has the holes cut so they fit both patterns perfectly. The REM part doesn't fit either one properly. The DMT part also crushes better which will allow for a better seal.

Up next: Installing Air Door Foam

Last Updated 05/29/08 08:49:41 PM