Monday, January 22, 2018

Front Disc Brake Conversion - Part 1

Like Sven, I was busy in 2017 with things other than our Mustangs. And like Sven, I can't say much about what I was working on either. Let's just say it involved (2) Ford Raptors and a whole lot of fun. I'm always amazed they actually pay me to do what I do!

But back to SusieQ. As I mentioned in the previous post, while in Australia, I decided that upgrading to power disc brakes was a must. Unfortunately not as many options out there as there used to be. Settled on Mustang Steve's 1994-2004, 13" Cobra Front Disc Conversion. It's a straight forward design, the majority of it being simple, laser-cut steel plates. Three issues I think if addressed though would make for a better design:

 Issue 1: The 2 rectangular plates in the photo below could be combined into 1. I'm guessing the reason was to reduce cost by laser cutting the pieces from standard stock thicknesses, rather than CNC machining a more complicated part. The large plate is .375" thick, the smaller one .100". In order to get this same stack height from a CNC part, they would need to start with a lasercut part from .500" plate, mill it down to .475", then step it to .375" in the outer mounting areas. This lasercut method works, but I dislike the extraneous parts. I was VERY tempted to correct this - and I'm not saying I still won't.    


Issue 1: (2) Lasercut parts could be (1) machined one

 Issue 2: This one is getting nit picky, but I would like to see them expand the adapter plate perimeter a bit and match the contours of the spindle. This would be so much cleaner looking. I know, it's hid behind the rotor once it's mounted. But whether it's hidden or not, I still know it looks like this. Quite possible there's a potential interference issue with another part if you grow the perimeter so I'm not going to throw too many rocks.


Issue 2: Adapter plate doesn't follow spindle contour


















  



Issue 3: Again, I think they are cutting costs by using a lasercut part here when a machined part would have been more appropriate. You can see the large gap between the bottom of the spindle and the ID of the adapter plate hole. Remember there are no backing plates on this set-up, so any high speed sprays of water are going to pass right through that hole - and right against the backside of the inner wheel bearing seal. They couldn't make the hole in the adapter plate any smaller or the back side of the hub wouldn't clear. I would suggest that a machined part here, with a stepped counter bore to eliminate that gap (but still allow for hub clearance, might be a better alternative. You would need to add a small drilled vertical hole in the stepped counterbore to allow water that could enter from the front side of the assembly to drain. But water coming from the front side is going to be mostly deflected by the rotor. What water that does end up inside that opening will just be "slow speed ricochets".  In their defense, I saw this same issue with both Vintage Venom and Street or Track's kits as well. So there may be a reason for this gap that I'm simply unaware of. 



Issue 3: Gap between spindle & adapter plate





















Once I got everything unboxed and sorted, I took the Dewalt with the abrasive pad to the edges and got rid of all the laser cut kerfs. Cleaned everything up, sprayed on a nice heavy coat of PMB 6525 (otherwise known as BMW silver) and popped into the powder coat oven at 400 deg for 20 min. Hard to see in the photo, but a very subtle hint of metallic in this silver. I like it. Sophisticated without being snobby :)



Stay tuned for our exciting Part 2 follow-on!!!






















3 comments:

  1. Good Lord RJ, there ain't no doubt you and I are cut from similar cloth! Anal retentive and PROUD! Ha! Nice to see you back on the project and getting your hands dirty! Feels good, don't it?! Cheers!

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  2. Thanks Sven - our continuing joke - how do you eat an elephant!!!!

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  3. Yeah RJ. I think we've all had a year of events that have sidetracked us. As one who has worked in production and manufacturing for years (before my current position) cost of production was a big deal. That's probably what you're seeing in the kit. Would you and I pay extra for a machined part? Depends on the $$$. The end game however is to have stopping power not available with drums. It's a smart and safe conversion. Glad to see you back at it.

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