Join Date: May 2001
Location: Jersey Shore (Not Seaside!)
Feedback Score: 0 reviews
We had used dozens of these on test vehicles over the years and as your own experience, they work very well. You will not have any ABS issues.
Now the warning. The reason for using DIH brakes rather then through the service caliper parking has to do with the type of friction material used in the service brake. Semi-metallic pads like all of the ones available for these trucks had a pretty good thermal expansion rate. The danger here is you park the vehicle, engage the hydraulic service brake, and as friction material and rotor cool they shrink back down and you loose hydraulic pressure and parking hold.
The question for the driver becomes how much pressure and how hot are my brakes. That is a problem even for those with brake thermocouples unless you know the friction material thermal swell characteristics.
Micro has taken steps to address this (after lawsuits from what I understand) that include a low pressure warning switch during the last decade or so. For me, it is essential that you hook this up to the horn or other warning circuit so if a problem occurs, you and anyone downstream will know there is an issue.
Now the probability of this happening is most likely rare, but running with a trailer has the highest potential for hot brakes, and the highest load placed on the parking brake activity.
You personally are probably aware of everything after the first sentence with your experience, but I thought I should put the rest in for anyone finding this in the future by using the search function.
On edit - for the parking brake to work well there are a couple of critical issues since the diameter of the DIH brake is so small compared to the vehicle the vehicles GVW. First the DIH lining has to be ground to a perfect radius,which is not necessarily the same as the drum. Next the rotor's DIH surface has to be grit blasted. You don't get this with aftermarket rotors, but if you know someone with a sand blaster you can improve your situation a little, but not up to OE standards. The last is running clearance, which for the DIH brake is tighter then a normal service brake. It should not be tightened to the point of dragging where the shoe lining wears out it ground radius advantage or wears off the grit blasted roughness.
The reason for the tightness gets you two advantages, both at the apply mechanism. The obvious is that it gains you more travel to apply higher pressure, and second all the application you can get at the center swing of pedal travel the higher the leverage. The farther off center-line the less mechanical advantage.
Former Vehicle Test Manager - Friction Products
03 F350SC 4x4 6.0 Auto 5/30/03
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Step Lights;Painted Flanges; Bypass Oil Filter; Heated Mirror Switch; Reverse Lights; 7.3L Fuel Reg Shim; 6 Disc Radio Speed Volume Mod; Coolant Filter, etc.
Last edited by FMTRVT; 06-20-2011 at 07:33 AM.