[James]

Was there a lot of fuel in the sump?

[James]

Hi Eric,

I noticed your mention of the exhaust manifolds not being flat on your Fairmont.

I own an Audi quattro turbo (the original rally winning one from the 80’s http://www.urquattro.info is my actual car/site), and these have an inherant weakness with the exhaust manifold. Original manifolds tend to crack over time, and reinforced aftermarket manifolds tend to warp when they go through their first heat cycles when new, requiring removal and machining flat again.
I don’t know if your engine in the Fairmont has aluminium or iron heads, but when this happens on the quattro (aluminium head), it can break manifold studs or pull them from the head.
Obviously studs pulled from the head is a royal PITA requiring drilling and helicoiling (and usually removal of the head to do it).

So just a heads-up really that it can happen, and hopefully now your manifolds are heat cycled and stress relieved, they’ve done all their warping and making them flat again will cure it.

[James]

Thanks for your reply.

Had a bit more of a play with it today.
Thing is, when the pulsation happens it’s not really a wub-wub-wub once per wheel revolution thing like a hub or rotor out of true, but more a brrrrrrrrrr – fast pulsing like ABS.

Today, I took it for a drive and could readily replicate the problem. I pulled the main electrical connection from the ABS pump under the bonnet. With that disconnected there is never any pulsing. On hard braking from 40mph I could lock it up, and interrestingly the back of the car wanted to overtake the front and got a bit sideways. Maybe it depends on the ABS being connected to do the brake front/rear proportioning properly, or maybe I just have a big V8 over the front wheels and the rears wanted to lock first?

I put the ABS pump connector back and the issue returned. I carried on messing around with test braking for about an hour and I think the problem has improved and may be gone (more general driving required to test fully).

As the car has an auto transmission, you can end up braking down from motorway speed to a set of red traffic lights, then hold the car on the brakes until the light goes green.
My current theory is I may have done this on new rotors & pads and deposited pad material onto the rotor in one spot, creating a very grabby part of the rotor, enough to mildly trigger the ABS – my constant braking today has created a more even layer of pad material on the rotor and improved things.

I had previously ruled out the ABS as the problem still occurred when I had a missing wheel speed sensor (ABS disabled), but it seems like the system still tries to operate best it can on 3 sensors because completely disconnecting the ABS pump stopped it.

[James]

I got a reply from the actual EricTheCarGuy on my first post. That’s pretty cool.
I’ve watched a lot of your videos here in England, enough that I went and found a browser plugin to let me disable my adblocker for your channels.

That wheel / hub interface bugged me enough to register here just so I could say
“ERIC!
YOU’RE DOING IT WRONG!”

I’m kidding.

I did read Kolton Sinclair’s comment (after you suggested it). I thought it was funny that you think I was over thinking it…
Yes it’s true that the clamping force between wheel & rotor will take the load normally, but I’d be concerned about impact from a pot hole etc.
I think it would bug me enough that I would have to find a better solution, so I thought I had to mention it on the slim chance you hadn’t realised.

Will be interesting to see how the wheel – strut clearance is after alignment.

[James]

Regardless of the length of the studs, I don’t think the centre bore of that wheel is far enough on to the hub to engage it properly with the spacers in place.
I think you might need wheels with a different offset. Any chance the Mustang has hubs which protrude further through the brake rotor?

[Author]

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