Fixed stripped holes in the knuckle (1 Viewer)

[Riad]

Well, after much searching I have purchased those caliper bolts from a local dealer. When I went to put'em on I found out that both holes in the DS knuckle are stripped . Dieing the holes with exact size didn't do any good. Those thread are pretty shallow and coarsed so every time I tried torqueing the bolt it snapped right out of the threads. So I went with slightly larger bolt. I have died the holes in size M14-2.0. I have put on the same size bolt on the hole now with 22mm heads (G8). That thing is bomb proof now . I think I'm gonna do the same for the PS front caliper and knuckle holes. These bolts are easy to find too, NAPA and most auto/hardware shops have these bolts. So now my problem is the caliper. What's the best way to make the caliper holes little bigger? I can die those holes too but I don't think it's going to work right.Do I grind or do I drill?

Thanks guys

 

[topend yobbo]

I drilled mine in a drill press when the same thing happened to me.

 

[clownmidget]

I vote drill them in a press but also, put some loctite on them bolts on re-install. this is a well known problem with them coming out, stripping out, etc.

 

[landtank]

I'm not sure what CLASS bolt was in there initially but a CLASS 8 is not the same as a GRADE 8 bolt, it is softer. A GRADE 8 bolt is similar to a CLASS 10.9 bolt.

I'm not saying the CLASS 8 isn't enough, just it isn't what you think it is.

 

[Riad]

I never heard any one breaking a G8 bolt(in caliper, slider, shock, winch..etc). Have you? Well I lost one off my shock years ago. I don't know what class the stock bolt is? But these sure look pretty beefier then the stock.

 

[landtank]

If you put in a metric bolt it's hardness is rated in CLASS not GRADE as far as I know.


Just so you'll understand why I'm posting this.

A M14 Class 8.8 bolt has a tensil strength rating of 116,000 psi

A M12 Class 10.9 bolt has a tensil strength rating of 145,000 psi

A 1/2" GRADE 5 bolt has tensil strength rating of 120,000 psi


that M14 is no where near a grade 8 strength, it's not even up to a grade 5

 

[Rich]

...I have died the holes in size M14-2.0...I think I'm gonna do the same for the PS front caliper and knuckle holes...What's the best way to make the caliper holes little bigger? I can die those holes too but I don't think it's going to work right...

You mean to say that you tapped the knuckle holes. Dies are used cut external threads. Taps are used to cut internal threads. Did you drill the knuckle first? 12mm drill is the proper size to used prior to tapping for M14-2.0.

The calipers would need to be drilled, not tapped. If you tapped the caliper M14-2.0 you would not be able to properly tighten it to the knuckle. 15.5 mm is the proper size clearance hole for a 14mm bolt.

 

[topend yobbo]

Rich is the second post invisible?

 

[firetruck41]

Rich is the second post invisible?

I can't see anywhere that it recommends the proper size hole to drill. Or a explanation of correct terminology. Is that the invisible part?

 

[Rich]

Rich is the second post invisible?

Yob, what's your point?

 

[Riad]

You mean to say that you tapped the knuckle holes. Dies are used cut external threads. Taps are used to cut internal threads. Did you drill the knuckle first? 12mm drill is the proper size to used prior to tapping for M14-2.0.

The calipers would need to be drilled, not tapped. If you tapped the caliper M14-2.0 you would not be able to properly tighten it to the knuckle. 15.5 mm is the proper size clearance hole for a 14mm bolt.

You're right. I mean to say tap . I did tap the caliper holes with M14-2.0 but as you said I couldn't get the bolt in all the way and there's a gap between the caliper and the knuckle bracket when I do that. I think if I tapped both holes with the caliper attached very tightly to the knuckle, that would work. Anyway, getting ready to drill the caliper this morning.

Landtank, thanks for that information

 

[landtank]

Landtank, thanks for that information

No problem, I myself saw an 8 on the head of a bolt and assumed it meant grade 8. It wasn't until recently when I was sourcing hardware for my front axle that I realised the difference.

When needing to alter brake components it's a good idea to make sure you get it right.

Maybe Dan can post up the class of that original bolt so you can be sure not to under rate the bolt.

 

[Riad]

I learned some thing new about the bolt classification, thanks to landtank . Yeah Dan, give us more tech info on this bolt classification. I will be SERIOUSLY concerend IF the M14-2.0 is weaker then the stock bolt.

Anyway, finally finished the work. Drilled the holes in the caliper, made it smooth. I had to cut the bolts, bring it down to stock length because it was too long. Also used the M14-2.0 die tool to clean the treads of both bolts after cutting them. Just came back from a test drive. it is good as new. When it gets little warmer I'm gonna do the passenger side. Thank you all for your input .

BTW: The bolt looks exactly like the stock bolt, not fully threaded, tapered under the head just like the stock bolt. Only difference is the size: M14-2.0.

 

[rtson]

This site is unbelievable!

I cannot believe the amount of knowledge exchanged within a week, and the concern for safety and getting it right I have definitely been educated about brake caliper bolts, and bolt classification. The combined experience of the posters and their knowledge cannot be found combined anywhere else. Definitetly not in a FSM. I remain a Rookie but am a willing learner. I just had to sit back and watch this thing take on its own life. Now I even understand pumpkin.
Thanks to all.

 

[rhyary]

The bolt on my rear caliber says 11. I just took it off last night.
It is a 17mm head. to clarify, it is the bolt that holds the caliber to the axle, and again the rear. I can look at the front tonight.