Does anyone know if the 15/16” 280ZX brake master cylinder is supposed to have a dust boot here:

That collar is 38mm. The only ones I can find that look right are 26mm.

It looks like there’s a groove to hold one on, and there’s clearly a channel for an o-ring, but I can’t find one in the exploded diagram. I have seen a bunch of aftermarket ones that have a dust boot, including the Wilwood 1” MC, but nothing for the factory ones.

My aftermarket did not include one or referenced it. That might be a Wilwood exclusive. Personally you wouldn’t know when the rear seal is going bad. Probably would drain inside the booster IMO

I’m guessing no one has problems with that then. Maybe the clue is in the name (dust cover) and it’s more about keeping things out than keeping things in.

I have dealt with dust boots on master cylinders like that in other applications and have sometimes had troubles getting them to fit through the hole in the firewall. Not sure if that's because they had swelled over time or if they were poor fitting aftermarket items.

Bottom line? Maybe measure the hole in the firewall and see if you even have room for a boot in there before you scour the universe looking for one?

On 5/25/2015 at 12:39 AM, Matthew Abate said:

Speaking of previous owner body work, here's a question: have you ever heard of anyone skim coating the roof with bondo in order to strengthen it? This is the one thing (other than riveting metal to the floor) that I feel like I have to undo immediately.

I knew these cars have thin metal, and I knew people did things to them to "fix" it, but this is the first I've heard of this.

He said it was rust free before he did it, and looking from the underside there aren't any dents, but this seems like a recipe for an unintentional convertible to me.

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That definitely sounds like a questionable repair choice — using bondo to “strengthen” a roof isn’t advisable since it’s not designed for structural support and can crack or separate over time. Even if the metal was rust-free, covering it with filler can trap moisture and cause hidden corrosion later. A better approach would be to properly strip the area, inspect for damage, and use professional roof coating services to restore durability and weather resistance without compromising the roof’s integrity.

Yeah, that definitely sounds risky bondo isn’t meant to strengthen a roof and could cause more issues over time. It’s best to remove it and inspect the metal properly before making any real repairs.