Brake problem

Deadguy · Post by **Deadguy** » Fri Dec 30, 2011 7:05 pm

I was swapping out the from 9" for 11" drum brakes today. The backing plates that mount to the hubs are held by 6 bolts. All were on tight when I unscrewed them. I swapped in the new 11" backing plate on the right side, 5 of the bolts went right back in, the sixth bolt just spins, like maybe the threads are stripped. I did the same thing on the other side, and it was a different bolt hole, but again one hole wouldn't hold the bolt. So, I'm thinking, that two hub bolt holes might be stripped, but isn't the axle made out of pretty heavy duty metal, so that would be less likely? And two bolts, one on each side? Any opinions?

wtb853 · Post by **wtb853** » Fri Dec 30, 2011 8:32 pm

I had a similar problem with stripped bolt holes on each steering knuckle. In my case, three holes were stripped where the locking hub bolts to the knuckle on the PS; one stripped hole on the DS. Different holes, but the same situation.

I am learning that cast iron can be temperamental; hard to weld, brittle, etc.

Deadguy · Post by **Deadguy** » Fri Dec 30, 2011 10:07 pm

hmmm. Maybe I should Helicoil them? Does anyone know the exact thresd size?

Post by **wesk** » Fri Dec 30, 2011 10:23 pm

Use your parts manual or measure the threads on the bolt you removed.

Deadguy · Post by **Deadguy** » Fri Dec 30, 2011 11:25 pm

I can't find the brake backing plate bolt size in my TM. like an idiot, I didn't bring one of the bolts with me, and my Jeep is locked up for the weekend. I was going to hit the local Fastenal, which has grade 8 bolts in fine thread, and get the next size of bolt up. I'll get a tap, enlarge the hole, clean up the shavings (so they don't rust in place) and screw in a slightly larger bolt All of which will be kind of hard to do if I don't know the thread size!

Post by **wesk** » Sat Dec 31, 2011 12:21 am

It would help if you would include the jeep model in all your posts or add it to your signature in your profile.

There are usually 7 holes in the axle tube but only 6 get bolts.

Also later A1's the bolts go from the inside out and use nuts and lock washers.

The A1 parts list has the bolts on page 244 right below the backing plate.

Deadguy · Post by **Deadguy** » Sat Dec 31, 2011 12:51 am

I wish the bolts came from the inside out and had lock washers! I don't have the parts manual, if that is separate from the TM. If it is, and you know where I can get a copy, I would love to get one. The brake backing plate has 7 holes actually, but the (I think it would be called the steering knuckle) behind it has only 6 holes for bolts.
I think I've edited my signature to show my make and model of vehicle now.

Post by **wesk** » Sat Dec 31, 2011 1:10 am

Every manual you need is at your fingertips. Download all of them in their PDF form and carry them with you on a CD or stick.

http://www.willysmjeeps.com/v2/modules. ... oad&cid=39

Now we know it's an M38A1 and it's the FRONT axle not the rear.

A heli-coil is your best bet.

Page 219 and they are listed under the spindle.
3/8-24NF x 3/4"

Deadguy · Post by **Deadguy** » Sat Dec 31, 2011 1:28 am

why do you recommend a helicoil over just tapping it to the next size up? I know all the bolts won't be the same size, but it will be a stronger, and easier, fix.

Post by **wesk** » Sat Dec 31, 2011 3:10 am

You are getting to close to the edge of the knuckle housing.

Another fix I have seen is to take a short bolt and thread it in from the inside of the knuckle so it looks like a stud from the outside of the knuckle. And you just use a nut and 5 bolts. The head was ground down a bit to clear everything inside the hub knuckle.

A properly installed heli-coil has at least 90 % of the original strength which is more than adequate if you apply the correct torque to the bolt. Too many guys pull the wrench for Jesus instead of using a torque wrench. Most of us old time full time mechanics know when to stop pulling on the wrench for a certain size bolt in certain materials. The rest of the folks need to use the torque wrench which will save them a lot of both money and time in the long run. There are plenty of general torque spec sheets out there to use for every size bolt. Whenever a service manual does not offer a specific torque value for a specific bolt or nut then we use the standard value for that size and thread bolt.

MODIFIED · Post by **MODIFIED** » Sat Dec 31, 2011 2:09 pm

wesk wrote:Too many guys pull the wrench for Jesus....

Post by **wesk** » Sat Dec 31, 2011 9:06 pm

An old habit from the aviation side of me where many inexperienced folks when they loose power on the airplane they just "pull the yoke or stick for Jesus" instead of correctly letting the nose down a bit to maintain a safe speed above stall.

Deadguy · Post by **Deadguy** » Tue Jan 03, 2012 1:11 am

Heli-coiled them today, everything came out fine, and over all I was pleased. Well, until I noticed that the Warn locking hub was missing 3 of the rod bearings...#@$%@, new hub time.

Bretto · Post by **Bretto** » Tue Jan 03, 2012 5:33 am

I'd bet you could maybe get spare parts from Warn

TomM · Post by **TomM** » Wed Jan 04, 2012 7:42 pm

Stripped knuckle threads are common a common problem. Drilling to a larger size creates problems with clearances on the backing plate or inside the knuckle. In my case bubba had badly butchered the backing plate so that he could get an oversized bolt into it.
Choices for repair are a replacement knuckle or stud conversion:
http://www.earlycj5.com/technical/steer ... d-upgrade/
I have no information on helicoil strength in the knuckle application.