Auto Mechanics: Heating Stripped Brake Bolts

[NC-Ratler]

Have a rear caliper with two stripped bolts, one that holds the pads, the other that mounts the caliper. Heating question. Will a small bottled propane torch heat hot enough to hopefully loosen rusted threads or do I need a MAP torch? Thx in advance.

 

[HotSoup]

Map

 

[JoeR]

Will a small bottled propane torch heat hot enough to hopefully loosen rusted threads or do I need a MAP torch? Thx in advance.

Propane? Unlikely. MAP, way more likely. Acetylene, of course. Can't be stuck if it's liquid.

Joe

 

[TobyScreams]

Definitely map. Heating the parts until they are equal temperatures doesn’t work very well. You want to think about what part to expand or not.

 

[pattersonj11]

Propane may do it. You won’t know until you try.

 

[bigten]

I've never had any luck doing that with propane as it heats too slowly. Slow heat expands bracket (metal) at the same rate as it does the bolt, so they both expand. You want to heat around the bolt quicker so that area expands first allowing bolt removal.

 

[Sharps40]

If propane is all ya have, get the larger part to ouch temp. Slather with candle wax, pb blaster or even gun oil. Let it get cold, try it rocking tight then loose, if no go, ouch and slather again, it'll pull the lube in and come loose eventually

 

[pattersonj11]

Is atf the other thing people like for seized up stuff? I know there is something common that a lot of people use.

 

[Sharps40]

That works with heat too

 

[dubbeltap69]

Heating the area up nice and hot and then quenching with a wet rag has worked to break rusted connections for us in the past. Heat up, reef on it, heat up, quench, reef on it, spray lubes, repeat x10...

Just dont get too hot of course and then quench because that can also lead to cracks especially with cast iron.

If the head strips off, I've also welded a nut to the head to get something to grip. Had to weld torx bits to torx screws before to get off.

Just keep at it.

 

[DrSpeed]

Have a rear caliper with two stripped bolts, one that holds the pads, the other that mounts the caliper. Heating question. Will a small bottled propane torch heat hot enough to hopefully loosen rusted threads or do I need a MAP torch? Thx in advance.

I haven't had much luck with propane/MAP heating in the past, for context what else have you tried?

Things that come to mind to try first are a 5x soak with PB blaster over an hour, then off center chiseling, or cutting a flat into it.

Then there is always the nuclear option, drill it out and keep a tap on hand if you miss the center. Ace will have the right tap, SAE or Metric.

 

[Papa_Smurf]

Soak it in 50/50 mix of atf and acetone, and let it sit overnight.

 

[NC-Ratler]

Thanks as a lot of fantastic information. I was unsure of propane and think it's not going to be hot enough. I will try the atf and acetone. I've been hitting it daily with PB Blaster. One bolt that holds the pads went from an octagon, to a circle, to mushed triangular clump of metal after several attempts with vice grips. I then went to remove the caliper but one of those bolts now is starting to smush so before going any further, I am trying everything from heat to oil to hammer and chisel first to loosen the rust. I have a few small MAP canisters but only propane nozzles. After going to Homedepot, Tractor Supply and Walmart to not find a single MAP nozzle, I ordered one online. I've never seen bolt heads mush like this early 2000s toyota and have worked on some older hondas and fords. Occasionally you get a striped head, but two out of three?

 

[Papa_Smurf]

Thanks as a lot of fantastic information. I was unsure of propane and think it's not going to be hot enough. I will try the atf and acetone. I've been hitting it daily with PB Blaster. One bolt that holds the pads went from an octagon, to a circle, to mushed triangular clump of metal after several attempts with vice grips. I then went to remove the caliper but one of those bolts now is starting to smush so before going any further, I am trying everything from heat to oil to hammer and chisel first to loosen the rust. I have a few small MAP canisters but only propane nozzles. After going to Homedepot, Tractor Supply and Walmart to not find a single MAP nozzle, I ordered one online. I've never seen bolt heads mush like this early 2000s toyota and have worked on some older hondas and fords. Occasionally you get a striped head, but two out of three?

might have to weld a nut on them to grab them with a wrench.

 

[NC-Ratler]

Thats the next attempt if it fails.

 

[dubbeltap69]

Post a pic so we can see the carnage.

 

[georgeeebuck]

Good luck. Keep at it ,give it heck.

 

[ellwoodjake]

Toyotas are the worst. I've never had any luck removing, and just have to snap them off, then drill and tap. The 12mm thread are then oversized to 1/2". I get new grade 8 bolts from the local hardware store. Calipers holes have to be slightly oversized as well, for the now larger bolts

 

[dubbeltap69]

Vermont taught me the value of anti-sieze on things. Amazing how things rusted up there.

Wheels literally rusted to the hubs. Only way to get off was to loosen the lugnuts and then drive around trying to hit potholes until they busted free.

 

[pattersonj11]

might have to weld a nut on them to grab them with a wrench.

This seems to always work. Not just the nut, but the heat.

 

[DuckyDave]

Borrow a "blue wrench" (acetylene torch) from a friend. As someone else mentioned the heat source must supply heat to desired area do rapidly that heat doesn't flow to the undesired are. Propane can't do that.
If you can't borrow acetylene torch then use good old Liquid Wrench. It has extremely low viscosity, probably lower than PB Blaster (television hype) so is drawn into the seized interface through capillary action. Lab testing on Instron equipment with controlled rusted fasteners has proven this. I have tried lots of methods on seized outboard fasteners (usually stainless to aluminium or stainless to iron, both grow wicked intermetallic in presence of saltwater) and Liquid Wrench worked best for me. Tried ATF (old formula and new) with acetone but these immiscible liquids separate out before I can apply--at least for me. Key to any penetrant is to wire brush clean the area where penetrant is to be applied, tap lightly to vibrate in and be patient--over several days if possible.
Good luck!

 

[NC-Ratler]

Ugggg, finally just got around to getting these bolts off, thankfully. MAP heated a few times, ATF/acetone and PB Blaster a few times a week for a few weeks, and hit several times with a punch and hammer to try and break the rust. I tapped it once with an air hammer and punch and deformed the soft bolt head as seen in the one photo. Attached a 14mm impact socket and hit it with the air gun - it was all or nothing at that point as after using a breaker bar, one bolt was already starting to round. The one bolt on the caliper clamps was toast, rounded and even with vice grips I was unable to remove. Just replaced the whole caliper head with new. Thankfully the two mounting bolts backed out as I was sure the rounding one was going to strip. Never seen such soft bolt heads.

Next step is to get the rotor off with 12mm bolts as the ebrake is holding it tight in place - nearly there. Thanks for all the help/tips.