Can you install a helicoil to repair stripped threads on a suspension fork brake post mount? Clearly you can; but would you feel comfortable riding a fork with this type of repair?
I recently found myself forced to find out when the threads on my fork’s lower post mount failed while adjusting a brake caliper. While prepping my bike the evening before a ride, I had loosened the bolts securing the brake caliper in order to improve caliper alignment. Upon securing the bolt, it almost secured, but the usual resistance at the wrench never came. Adding a quarter turn at the allen wrench, it still didn’t secure.
This is the part when panic sets in. Backing off the bolt, I tried again, a bit more gingerly, with the same results. Backing the bolt out, my concerns were realized. There was thread material on the bolts and the brake post threads had stripped.
My first step was to thread a longer bolt in to see if I still secure the caliper reaching deeper to more secure threads. Perhaps the fork would still be usable for my ride. Unfortunately, the process was repeated; the existing threads simply didn’t have enough mass to hold the bolt in. Shit.
Step one: research
It’s been years since I’ve had to address stripped threads, and the first time I’ve experienced the issue on personal equipment. During my tenure as a mechanic in top-level service departments at premier bike shops, I’ve solved a multitude of problems, but since I’m rusty I took a step back to assess my options.
I could do one of three things to address the issue:
- Replace the fork lowers
- Determine a way to repair the threads
- Buy a new fork altogether
I was understandably upset the thread gave up the way they did, so purchasing a new fork was the first thing that crossed my mind. I’ve been really happy with the performance of the Rockshox Pike and its been our go-to for our trail bikes. The X-Fusion Trace was going to need some tuning anyway, as the fork’s spring rate has been far too linear for my preferences, bottoming out when riding aggressively on burly trails.
However, I already have two Pike forks lying on the floor of the garage. Unfortunately both are for 650b wheels as opposed to 29″, the size required. The reason I chose to go with the X-Fusion in the first place was cost-based, and until I did something with the Pike forks, it was going to be hard to justify the purchase of new equipment. It was time weigh the pros and cons.
Option one: replace the fork lowers. I wasn’t excited about the prospect of acquiring new fork lowers. After all, I had just recently assembled this bike, and to top it off, added sweet custom decals to make this thing unique. I’m a rather lazy bike mechanic, and even if I was able to secure replacement fork lowers as a warranty or low cost replacement, I’d still have to disassemble the fork. (I had recently adjusted the travel of the Trace from 100mm to 120mm). Plus the replacement lower legs would lack the cool custom decals. This would be a massive pain in the ass, so it was demoted to the last option.
Option two: repair the threads. Thread repair kits are common solutions to stripped threads. When threads are damaged, the first thing to try would be repairing the existing threads with a tap, and trying a longer bolt. As I had already tried this approach, I was moving on to attempting to repair the threads by installing new ones in the form of a Helicoil insert. Helicoils are thread repair kits that replace indigenous material with a stronger steel threaded insert that is threaded in. (the Heli-Coil Kit I purchased is the M6x1 Metric off Amazon)
Unfortunately, none of my local auto or hardwear stores had the thread repair kit, so I turned to Amazon and had everything I needed in a few days.
Installing a Helicoil thread repair kit
The first part of the repair is to properly prepare the hole. This aspect of the repair is the most nerve-racking of the process, as it consists of drilling out the old threads. Fortunately, there’s quite a bit of documentation online, making it a straightforward fix for a handy and experienced home mechanic. (scroll down to view some embedded video walk-throughs)
There are plenty of how-to articles on installing a Helicoil thread repair kit, and seeing how rusty I am, this article isn’t meant as a how-to but a documentation of the before and after. The real question I wanted the answer to is, “Do I trust the repaired threads?”
Fast forward: 3 months later
I’ve been riding the fork with the repaired brake post threads for a few months without issues. The steel insert is arguably stronger than the stock threads in the fork.
However, I’m not entirely confident in the security of the repair for a few reasons; one, I believe this to be a warranty issue. I didn’t put a lot of force on the threads when they were stripped. If it had been a user error, I’d be a lot more confident in this repair. The fork was mounted on a 5″ travel Evil Following and I’m a skilled rider who enjoys high speeds, technical terrain, and hard braking. I’m confident in the steel threaded insert, but seeing as how the fork had soft materials that failed, I could see my newly cut threads failing a second time, especially considering the forces from the 7″ rotor I run on my forks.
While I don’t plan on replacing the lower legs any time soon, I’ll have more fun riding if I have full confidence in my equipment, so I pulled the fork. I’ll end up running it on another bike down the road, but likely on a hardtail. I don’t push it when riding rigid frames, and tend to ride hardtails on less steep terrain. I’ll also utilize a 6″ rotor instead of a 7″ rotor which would put less stress on the mount.
Looking to learn more on thread repairs? Here are a few videos I dug up on YouTube to get you started.
https://www.youtube.com/watch?v=-_azEsNkA9Q
https://www.youtube.com/watch?v=46bIm2xaLuc
https://www.youtube.com/watch?v=T3I6RRHK9dE
Reader Feedback – Updated April 18th, 2025
<name withheld> writes:
While working on a brake noise issue, I had a similar issue on a Fox 36 fork. I only stripped the outer few millimeters of threads because apparently I had the wrong bolt in the brake caliper (the shorter of the two).
There are plenty of threads for the longer bolt to grab. But I know that there’s a ratio between bolt diameter and thread depth for maximum holding power, which varies based on the material. And the fork lowers are definitely soft. So I’m debating whether to leave it as is er with the appropriate length bolt, tap it and helicoil, or get new lowers (an expensive proposition).
Your article is from 2017… Just curious if you kept riding the fork. And whether you have ever experienced any issues.
Thanks for writing in <********>! I do still have this fork, though it’s not in rotation at the moment. However, it did live on some other bikes and builds for a while, and the helicoil repair has not been an issue yet. I replaced it on the Evil Following build with a new Fox 34 fork and ran it on a hardtail after reducing the suspension travel. I’m not riding my hardtail at the same pace as the Evil, so it didn’t affect my confidence on the bike or have me second-guessing.
For your build, I’d say if it’s only a few threads, you’re probably ok, though I’d look to see if it was possible to run a longer bolt to keep the same level of thread engagement. I’d check it regularly, and if you were ever in doubt, consider replacing it down the road.
I’ve certainly replaced parts for lesser reasons, and if it bothers you enough to affect your peace of mind, it might be worth changing. I change out my carbon handlebars whenever they get a scratch for the same reasons.