Name that tap... size


#1

Please tell me the tap size for the thread in the hole of the caliper guide pin, front brakes on a 2000 Dodge Durango 2WD 5.2 eng. Or the matching thread from Mopar part 04886075AA. A prior brake job stripped one hole and I was not told, and a coil insert was used. Which was not exact enough, the inner pad on that wheel wore out way before the other front pads. Even though it had issues, this vehicle is approaching 200k miles, this maybe its last brake job so i’m trying the insert route again. But the pin is binding before its threaded in fully. So want to tap the hole after i insert the coil. But trying to ID the thread has been a problem. The Dodge dealer parts man said “they don’t have that info, try the service dept”, The Service Mgr (Assist?) claimed ignorance of the info i was requesting. One parts store counterman told me the thread on a brand new pin was damaged, another tried matching on the store thread guide and a thread repair kit, but was not sure. He suggested calling Dodge. I called, submitted the info request for tech dept, a few hours later got a call back, “We don’t keep info on vehicles 10 years old.” I have tried the taps i have on hand on the good hole, 8.0x1.25 went in loosely, 5/16 18 & 24 did not fit (i did not push it, did not want to ruin good threads.) Another parts man who owned a Durango and the same problem, suggested an self tapping oversized pin, but the previous mod to the hole may not permit that. Any other suggestions?

Thanks
Jim


#2

Jim,

Take a new guide pin to a machine shop and have them measure it. A good machine shop can give you the information you are asking for. I had a part off of a piece of machinery in my shop which had a thread I needed a size for. A close friend of mine who works for a major airline in their machine shop was able to get me the measurement I was looking for and actually had the die for it.

transman


#3

If there is enough metal to tap a larger thread than the original thread, you get to choose the thread and just need to match the replacement bolts to match, right? I’ve done this. Am I missing something?


#4

The caliper guide pin should be 8.0mm X 1.25. The Mopar brake knuckle repair kit #05016155AA includes (25) stainless steel heli-coils, outside thread is 9mm X 1.25.


#5

Thanks for the quick responses, Transman618 I had not thought of visiting a machine shop but will if nothing else works out. kizwiki,the previous work has enlarged the hole to accept the coil insert, which came out in little pieces. I did not know of its origins, without it the guide pin just spun in place. I needed to replace the insert, I found a product call Perma-coil. Its avaiable in a range of sizes, I tried M8x1.25 and 5/16-18. The M8 matched the best as far as I could see, but once installed in the hole it proved not a workable solution. First try failed, maybe I did not start right, the coil ate up threads of a new pin. I put another new pin in with no insert, test drove it. The pin stayed place, brakes worked fine but I could not trust it.
I tried another M8 insert and the old pin, it failed to thread all the way. Another test drive, brakes are fine but again can’t be trusted. Try to remove the pin, allen socket strips. I have to drill and use a screw extractor to back it out. Bought two Mopar pins, which is were I am now. I will try to get the repair kit Nevada_545 reported. The pins are larger 8mmx1.25, I tried again tonight another stores thread measuring jig. 10mx1.5 fits best but does not feel tight while threading in, no 9mmx1.25 hole to test.
Maybe there is physical difference between Perma-coil and Heli-coil products, I hope so. Wish me luck, one of local dealers didn’t even have the pins in stock.

Thanks Again
Jim


#6

The holes in the steering knuckle may not have been tapped properly, you should get a 9mm X 1.25 tap and run it all the way though the caliper mount holes to clean them out.
The Mopar kit is very expensive, you can find a heli-coil kit at a auto part store for less than $40, however finding stainless steel inserts may be difficult. Stainless steel is used in this application so your caliper doesn’t come loose due to rust.


#7

This should be repairable, but if worse comes to worse, you can get a used steering knuckle from a salvage yard. It shouldn’t be terribly expensive nor difficult to find. You will just have to make sure the caliper mounting points are in good condition and will have to again get the original hardware.


#8

After dropping my wife at work this morning, I stopped at another auto-parts store. They are able get a 9mmx1.25 heli-coil kit later today for $50. But…For kicks I just checked online heli-coil e-catalog does not list m9x1.25 and is not an option in the selection Wizard. So I’ll see what comes in today.


#9

The Mopar brake knuckle repair kit #0516155AA, did not show up in the system according to Rick Hendrick’s partsman. I did get from a NAPA store, part# 770-3411 HeliCoil Metric Thread Repair Kit Sise: M9x1.25. Unfortunately I did not check what drill I needed before I came home, so another trip looking for drill size “U” (.3680).
These inserts do seam to fit the pin best, but loose, I suppose in place they compress somewhat. I should see how well the tap fits the modified hole. Maybe I will not need the drill. I’ii be back.
Jim


#10

Good job all. The tap did not need the drill this time. Brakes are reinstalled, test drive complete. Lets see what can we “fix” next.

THANK YOU
Jim