[Bob Lincoln]

Last weekend the left front rigid brake line blew. It was one of the few original lines left on the truck, and fortunately it happened in the driveway. I already had a new caliper and flex hose on hand, and I have a 20" new brake line.

So last night, I had enough time before dark to remove the tire, caliper and flex hose. I transferred the pads to the new caliper (pads and rotor were new 4 years ago, almost no wear) and greased the bolts. I threaded them about 1 1/2 turns by hand, and then tightened them with my 3/8" drive socket. The top bolt seated tightly with no issue. The bottom bolt, which had been in tight, stripped out the thread in the steering knuckle. It starts to snug, then slips again. Not good. I mounted the flex hose and called it a night.

I'm wondering what the best way is to repair this. I don't know if a permanent threadlocker will hold, or if by unscrewing and screwing it in once, there will be any more thread left to grip. I don't have any helicoil or threading tools, or any experience doing that. I heard that this is a common problem with Dakotas. Can anyone advise? Thanks.

 

[stevenspeaking]

Bob, The part is no longer available from Mopar. However, all the components should be available aftermarket.


Best wishes with this project,
Steven


PARTS REQUIRED:

Qty Part No. Description AR (1) 05016155AA Kit, Brake Knuckle Thread Repair Includes:
23/64 Drill Bit
M9 X 1.25 Tap
Heli-Coil Installation Tool
Heli-Coil Tang Break-Off Rod
(25) M9 X 1.25 Stainless Steel Heli-Coils
REPAIR PROCEDURE:

1. Using the 23/64 in. drill, drill through the brake caliper mounting attachment hole keeping the drillperpendicular to the knuckle.
2. Using the M9 X 1.25 tap, tap the drilled hole ensuring to tap the hole entirely through.
3. Install a Heli-Coil insert onto the installation tool (tool number 3747-9). Be sure the tang is properly engaged into the driving contour of the tool.
4. Install the Heli-Coil into the drilled/tapped hole by rotating the tool and exerting slight pressure onto the tool/Heli-Coil and into the drilled/tapped hole. Continue to rotate the tool until the insert is located 1/4 to 1/2 turn below the steering knuckle surface.
5. Back the Heli-Coil installation tool out of the installed Heli-Coil. Then, remove the tang from the Heli-Coil by breaking the tang off using the tang break-off tool. Place the break-off tool into the assembled insert until it rests on the Heli-Coil tang. Holding the tool squarely, strike the tool sharply with a hammer.
6. If the vehicle has a bolt-on brake caliper mounting adapter, install the adapter. Refer to the appropriate Service Manual for information regarding proper brake caliper adapter mounting information. If the brake caliper mounts directly to the steering knuckle, install the rotor.
7. Install the caliper using new mounting bolts p/n 04886075AA in any location that had a Heli-Coil installed. Tighten the bolts to 30 - 35 N• m (22-26 ft. lbs.).
8. Install the tire/wheel assembly.
9. Lower the vehicle.

 

[Bob Lincoln]

Thanks, I've been reading about various solutions. Another engineer here is horrified at the idea of a helicoil in a critical application. Others have used oversize bolts, some say they hold, others say they're often one-time use and then let go. Still others say to weld a plug, drill and re-thread. Some say use a new knuckle. Safety is a priority, but I can't spend over $1,000 on this truck.

 

[valiant67]

I don't know about the 1992, but there was a Help bolt for my 1999 Dakota that had the same issue. I'm guessing it was slightly oversized and self tapping (it's been a couple years ago). In the mean time I had gathered spare knuckles to fix the issue but the truck was totaled before I had to dig into the brakes again.

 

[AllanC]

I threaded them about 1 1/2 turns by hand, and then tightened them with my 3/8" drive socket. The top bolt seated tightly with no issue. The bottom bolt, which had been in tight, stripped out the thread in the steering knuckle. It starts to snug, then slips again. Not good

Is it possible to use a longer bolt and allow it to protrude from the mounting on the knuckle? Then put a hex nut on the bolt and this will hold it in place. I imagine clearance with the disc rotor is a concern. But you could even shave a hex nut and make it thinner. If there is clearance to not interfere with the rotor, this would be a good solution and more reliable and safer than using thread locker or a heli coil insert.

 

[Bob Lincoln]

Nope, someone suggested that on another forum. No clearance at all to do that. It would interfere with the inner pad.

Chrysler's authorized solution is Helicoil. Other types of inserts include Timesert and Keensert.

 

[dak4x4]

I fixed the same problem on a 96 Chrysler car with a steel threaded insert from the hardware store. It looked like a tube with threads on the exterior and interor and a screwdriver slot for seating it. It's not a helicoil. You just have to ream out the stripped hole and run a tap into it, but not all the way as you want some partially cut threads to provide grip for the insert; the threaded insert is screwed in with permanent Locktite. The insert provides new threads. That repair is still on the road...

 

[Bob Lincoln]

Yes, that's the principle of the Keensert and Timesert.

I don't think I want to risk drilling off-center of the axis of the bolt, as that will cause the caliper to bind when it slides, and ruin the brakes. So I'll pay a pro to fix it.

 

[dak4x4]

Bob, if drilling a new hole freehand with a power drill, it's easy enough to put it in crooked. This is not the case with your situation.

With reaming out an existing hole a tad larger, the drill wlll follow the existing hole and be in alignment, unless you intentionally lean on the drill sideways to make the hole cocked off center. Then comes the tap. Tapping a hole by hand the tap will automatically align with the hole, even more so than the drill-- in otherwords putting in that threaded insert is a piece of cake.

 

[Bob Lincoln]

Maybe so. I just don't know how much degree of error the caliper can tolerate, if one bolt axis is off by several degrees from the other. And I'm not sure I can readily access the back of the steering knuckle to install the helicoil, even with the wheel turned to the right (it's the LF caliper). The truck is on the ground outside in my driveway, so it's awkward compared to having a lift and standing under it. Very little range of motion available for my arms. To me, if I can be sure someone will get it right for $100, that's better than me gambling with a $26 kit that I buy and use myself.

A neighbor is a mechanic, I will ask his opinion.

 

[Bob Lincoln]

Will have to do this after the hurricane, as I'm working in the driveway.

The NAPA kit didn't have a Heli-Coil Tang Break-Off Rod. It sounds like the tang faces toward the bolt head as you screw in the insert, and not at the bottom of the thread. Is this correct? How do I break off the tang? Can I buy the tool separately? I only have the set of helicoils, the tap and the installation tool.

 

[Bob Lincoln]

OK, finally had a chance to tackle this today. I removed the wheel and caliper and rotor, then on a hunch, tried threading the existing bolts bolts in, when I could observe the entire hole. These are replacement hex head bolts that I put in a few years ago. Top bolt hole fine, bottom still stripped. Then I tried threading the OEM style bolt that came with the caliper, into the hole. This is a T-40 torx bolt that I dislike, because they rust and lose the torx contour, and are nearly impossible to remove. A neighbor helped me remove the original by hammering a bit into the old one and forcing it out (maybe that did a job on the threads).

Anyway, the new OEM style bolt went all the way in and tightened up snug, no slipping. Tried it 3 times in a row, torqued to the 20 ft-lb setting. Tight. So I put the rotor and caliper back on, greased the bolts, put anti-seize on the top bolt threads and blue threadlocker (all I had on hand) on the bottom bolt as extra insurance. Carefully threaded them in by hand, tightened both, and all is well!!

Will let the threadlocker dry 24 hours. I'll save the helicoil in case the threads give out for good some day.

Round 2: I had taken my 93 Daytona off the road because I smelled a very faint odor of gas (but no dripping anywhere), and saw melted undercoating on the tank and on the lines behind the gas filter. I suspected I had a tiny pinhole leak that wasn't yet dripping, and wanted to play it safe. So it's sat for 3 weeks while I drove the Turbo Z.

Looked under it more carefully today, ran it, could not smell or see any gas. Faint exhaust odor, as the motor was cold and rich. Then the scales were removed from my eyes:

THE REASON THE UNDERCOATING WAS MELTED WAS BECAUSE OF THE BRAKE LINE LEAK 2 MONTHS AGO!!

It had spurted out when I was tightening the new RR rigid line, and got on both the gas tank and the fuel line in front of the wheel.

I believe the faint gas smell was because I had recently topped it off, and a little got in the fenderwell when it clicked off.

Two cars back on the road within one hour! Now to fix the washing machine that won't do the spin cycle.

 

[NYBo]

I just found out my '99 has the same problem. It already had the oversize bolt installed, so the Helicoil kit it is for mine.

 

[valiant67]

I just found out my '99 has the same problem. It already had the oversize bolt installed, so the Helicoil kit it is for mine.

I grabbed a set of 2003 knuckles back during cash for clunkers. There were a few reasons.

• I had an oversized bolt already (like you do).
• Second the threads seemed really susceptible to corrosion and the truck had started life up north though everything else was solid those threads were weak.
• The 2003 caliper mounting system is much better.
• The rotors are larger and you get dual piston calipers.

The only real downside is you can't run the 2003 brakes with 15" wheels. But mine was a Dakota R/T with 17" wheels so I was set. I got the front knuckles loaded with calipers and rotors and the rear axle with rear discs for less than $200.
I'm gonna do the swap on the current Dakota since the one I bought the parts for got totaled.
This is just one thing you might want to consider, but it is more work than a helicoil for sure.