Community Forums

hawg6 · 11-06-2008, 06:02 PM

I'm in the process of changing the calipers on my W-22 chassis. The guide pins on the top of the calipers have a fluted portion that appears to be made of plastic, while the bottom pins are round steel with no fluting. The right rear is the side that locked up this week. The upper pin on the right side is somewhat tight, or at least a lot tighter than the left top. The left is the side that locked up in June. The straight bottom pins move freely, much freer than the top fluted pins. All the pins were lubed before either of the failures. Does anyone know the reason for two different pin configurations? Is there any reason not to use the straight all steel pins top and bottom, as they appear to stay freer than the pins with the plastic like material? As with both failures the brakes freed up after sitting over night.

hawg6 · 11-06-2008, 06:02 PM

I'm in the process of changing the calipers on my W-22 chassis. The guide pins on the top of the calipers have a fluted portion that appears to be made of plastic, while the bottom pins are round steel with no fluting. The right rear is the side that locked up this week. The upper pin on the right side is somewhat tight, or at least a lot tighter than the left top. The left is the side that locked up in June. The straight bottom pins move freely, much freer than the top fluted pins. All the pins were lubed before either of the failures. Does anyone know the reason for two different pin configurations? Is there any reason not to use the straight all steel pins top and bottom, as they appear to stay freer than the pins with the plastic like material? As with both failures the brakes freed up after sitting over night.

DriVer · 11-06-2008, 06:18 PM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by hawg6:
I'm in the process of changing the calipers on my W-22 chassis. The guide pins on the top of the calipers have a fluted portion that appears to be made of plastic, while the bottom pins are round steel with no fluting. The right rear is the side that locked up this week. The upper pin on the right side is somewhat tight, or at least a lot tighter than the left top. The left is the side that locked up in June. The straight bottom pins move freely, much freer than the top fluted pins. All the pins were lubed before either of the failures. Does anyone know the reason for two different pin configurations? Is there any reason not to use the straight all steel pins top and bottom, as they appear to stay freer than the pins with the plastic like material? As with both failures the brakes freed up after sitting over night. </div></BLOCKQUOTE>hawg6, Please refer to the Bosch pin slide disk brake thread that is posted at the top of the forum in the bold stickies.

One of those pins is the leading pin and the other is a trailing pin. Please refer to the publication I spoke about and it will detail all of this information for you.

The pin with the rubber bushing is the trailing pin. The one without is the leading pin.

hawg6 · 11-07-2008, 05:10 PM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by DriVer:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by hawg6:
I'm in the process of changing the calipers on my W-22 chassis. The guide pins on the top of the calipers have a fluted portion that appears to be made of plastic, while the bottom pins are round steel with no fluting. The right rear is the side that locked up this week. The upper pin on the right side is somewhat tight, or at least a lot tighter than the left top. The left is the side that locked up in June. The straight bottom pins move freely, much freer than the top fluted pins. All the pins were lubed before either of the failures. Does anyone know the reason for two different pin configurations? Is there any reason not to use the straight all steel pins top and bottom, as they appear to stay freer than the pins with the plastic like material? As with both failures the brakes freed up after sitting over night. </div></BLOCKQUOTE>hawg6, Please refer to the Bosch pin slide disk brake thread that is posted at the top of the forum in the bold stickies.

One of those pins is the leading pin and the other is a trailing pin. Please refer to the publication I spoke about and it will detail all of this information for you.

The pin with the rubber bushing is the trailing pin. The one without is the leading pin. </div></BLOCKQUOTE>Thanks Driver. Along with the four new calipers, I decided to replace all the pins and purchased four pin kits. I called Bosch technical support to see if the Shell Albida PPS 1 grease which is listed as "only use" in their Technical Manual is still the correct grease assuming their manual is up to date. He was of no help. The kits come with two packets of grease with a Bosch part number so I"m not in need of the special grease at this time. I tried to track down a source for the Shell grease, but had no luck through Shell and some distributors. I asked my local Workhorse service center for information on the grease they are using. They stated they use whatever wheel bearing grease they have on hand????? Still waiting for Bosch/Workhorse/NHTSA to come forward as I feel I've replaced the as shipped parts with parts of the same configuration and therefore are destine to the same failure. Hope I have bought safety until we see a resolution from Bosch/Workhorse/NHTSA. You came through again Driver

DriVer · 11-07-2008, 05:49 PM

The requirement is for specifically marked "High Temperature Brake Grease" not wheel bearing grease. Wheel bearing grease is meant to be used in a closed vessel or compartment on bearings and races and it is not subjected directly to high temperatures or direct exposure to the environment. HTBG also does not readily wash off or become contaminated by exposure to moisture or water.

From what I understand, once the HTBG is applied, you're not supposed to really see it on the caliper components since it's applied on the slides and pins which are largely covered by the caliper housing. If you do see grease I believe it's too much and in the wrong place.

In my opinion, this is sort of a validation as to why only a limited quantity of grease ships with the caliper. A little bit in the right place goes a long way.

MikeT · 11-08-2008, 04:54 AM

Flush the brake fluid

hawg6 · 11-08-2008, 05:28 PM

I installed the first set of new caliper guide pins. The the new trailing pin fits the same as old pin, with the rubber bushing fitting somewhat tight. It is tight to the point that the grease is wiped from under the fluted rubber bushing when the pin is installed. The lead pin moves in and out with very little effort, but the trailing pin requires much more pressure to move it in and out. The tightness of the old pins is what prompted me to change the pins along with the new calipers. Tried to get information from my Workhorse service center, but they could not help. Hopefully someone else has installed new pins and can shed some light on the pin tightness. Also, does anyone know the purpose of the rubber bushing on the trailing pin?