Hello again, I believe I have ruined my new and expensive fiero store caliper. I was tightening down the banjo bolt and following the official pontiac service manual (why would it be wrong?) tightened the dry bolt down to 30 ft lbs. After reading online that 30 is way too tight for a banjo bolt on an aluminum caliper, I backed off the bolt and snugged it back down after fitting it with new crush washers. Fast forward to today and when filling back up my master cylinder (I'm an idiot and let it run dry) the caliper was leaking heavily from the banjo bolt. Here's what the threads looks like:
One of my friends says it looks cross threaded, another says it looks fine. What do you all think?
If it is, is there any way to fix it, like could I drill and tap the hole, or did I just waste $150?
Thanks, Doggo
[This message has been edited by Doggo (edited 08-19-2024).]
That 31lbs is correct. You may need torque it back down to that spec to stop the leak. Also, the best way to see if it's cross threaded is to try to install the bolt by hand. If it threads all the way in, you're fine. If you torque it to that 31lbs and it keeps spinning, then you're stripped out. From the photo, the threads look fine.
[This message has been edited by IMSA GT (edited 08-19-2024).]
BTW My official Pontiac Fiero service manual says 33 lbs. ft DRY torque which I didn't have any problems when reinstalling my 'dry' calipers. If the caliper has fluid in the threads, some members will lower the official torque at ~20 lbs. ft.
My advice is to get new bolts/crush washers first Then 'feel' when treading in the new bolt and like IMSA GT said; "By Hand" If all is good, install the hose/bolt/washer and start at 15 lbs./ft, then to 25 lbs./ft. and finally at 30-33 lbs. ft and keep an eye on the joint... If the bolt won't hold the torque, you have a 'real' problem......
------------------ Original Owner of a Silver '88 GT Under 'Production Refurbishment' @ 136k Miles
Hello again, I believe I have ruined my new and expensive fiero store caliper. I was tightening down the banjo bolt and following the official pontiac service manual (why would it be wrong?) tightened the dry bolt down to 30 ft lbs. After reading online that 30 is way too tight for a banjo bolt on an aluminum caliper, I backed off the bolt and snugged it back down after fitting it with new crush washers. Fast forward to today and when filling back up my master cylinder (I'm an idiot and let it run dry) the caliper was leaking heavily from the banjo bolt. Here's what the threads looks like:
One of my friends says it looks cross threaded, another says it looks fine. What do you all think?
If it is, is there any way to fix it, like could I drill and tap the hole, or did I just waste $150?
Thanks, Doggo
does the banjo bolt tighten down by hand? if you need a tool it's pretty bad(not to fully tighten it but to get it close to being fully threaded down) unfortunately I don't have any front caliper cores floating around right now but I have rears somewhere. my recommendation if you need another is to try rock auto because they are only 50 there
[This message has been edited by cartercarbaficionado (edited 08-20-2024).]
Wow! Thanks for all the quick replies guys, I really appreciate your expertise. I guess what I'll end up doing is getting a new bolt + washers and see if it'll go in by hand. I shall report back tomorrow... and if all goes well, it's on to the parking brake, which I am not looking forward to.
[This message has been edited by Doggo (edited 08-20-2024).]
...the caliper was leaking heavily from the banjo bolt.
It's possible I just imagined reading this here at some point in the past ... but I seem to recall someone having an issue with the banjo bolt leaking no matter how tight it was... and it turned out it was due to the bolt itself bottoming out in the caliper before it was tight against the brake hose fitting. This was due to either the new brake hose fitting being narrower or the banjo bolt being a bit longer. Whatever it was, the solution was to use three washers instead of two.
By the way, in case you're running short of crush washers... the copper ones can be re-used after they've been heated red hot with a propane torch and then allowed to cool.
[This message has been edited by Patrick (edited 08-20-2024).]
So it doesn't matter if each of the rear calipers are different?
it does but they carry both last I checked which granted was a few months ago. I do have some cores that just need a rebuild kit thrown in if you need one. just let me know which side you need and I'll see whether or not that's the one I need to drill out a broken bleeder on
Good Point of 'Squeeze' Area of Patrick's comment above as I have seen different thickness of brake crush washers.....
Your Job Doggo is to: By Hand; thread the banjo bolt into the caliper and bottom-out the threads: Measure from the caliper surface to the bottom of the banjo bolt head.
Next, put two crush washers on the brake hose fitting and Measure the assembly {i.e. the Out Diameter}
The first 'Measure' MUST be smaller than the second 'Measure'
If NOT, find 'thicker' crush washers or perhaps the caliper threads are not deep enough.....
------------------ Original Owner of a Silver '88 GT Under 'Production Refurbishment' @ 136k Miles
Haha, yeah oops I feel a little embarrassed now. When I wrote that I had just quickly ran out to my garage and tried to thread the bolt in without even thinking about the hose. When Vintage gave me a little experiment to do I went out and did it the correct way.
perfect. if you really need a spare I have one sitting on the bench. You'll have to order a rebuild kit off rock auto if you can't make your current one work (just stack crush washers. 2 on bottom one on top and see what happens i guess. it certainly couldn't hurt) and then we will pm about shipping and such and I'll teach you how to rebuild one of these
IMHO - Using three brake crush washers is SO "Mickey Mouse"
Oh for sure, what an abomination!
Seriously though... if I had a leak at a banjo bolt that could be completely and safely rectified by simply adding an additional crush washer that I had on hand, I sure as heck wouldn't bother driving several miles just to buy a thicker crush washer. That's SO OCPD IMHO.
[This message has been edited by Patrick (edited 08-20-2024).]
IMHO - Using three brake crush washers is SO "Mickey Mouse"
If you think 3 is bad you would die at how many were on the 88 formula. I was doing the brakes and putting new hoses on and I wish I was kidding but there was 7 normal crush washers on the passenger Side caliper. I used 2 thick ones that are sized for a cpi fuel system shrader. only reason i even suggested trying 3 is because if that seals up at all then 2 thick ones will be completely fine
[This message has been edited by cartercarbaficionado (edited 08-20-2024).]
Seriously though... if I had a leak at a banjo bolt that could be completely and safely rectified by simply adding an additional crush washer that I had on hand, I sure as heck wouldn't bother driving several miles just to buy a thicker crush washer. That's SO OCPD IMHO.
My roommate is very insistent that we simply over tightened the banjo bolt and now the soft brass of it is squished. I don't buy it but I'll humor him. He could use a good humbling anyway. Regardless I need to get more washers, so to the hardware store it is!
UPDATE: the banjo bolt DOES NOT thread in by hand. It gets about halfway in then becomes impossible to snug any further with my fingers
Sounds like you need to run a bottoming tap through the threads, or the banjo bolt has a defect.
Other idea: assuming it is the piston which was defective on your original caliper, maybe you can use the replacement piston in your original caliper housing (which presumably has a good threaded hole).
quote
Originally posted by Vintage-Nut: By Hand; thread the banjo bolt into the caliper and bottom-out the threads: Measure from the caliper surface to the bottom of the banjo bolt head.
Next, put two crush washers on the brake hose fitting and Measure the assembly {i.e. the Out Diameter}
The first 'Measure' MUST be smaller than the second 'Measure'
This is good advice, and is applicable to bolted joints in general.
quote
Originally posted by Patrick: Oh for sure, what an abomination!
Seriously though... if I had a leak at a banjo bolt that could be completely and safely rectified by simply adding an additional crush washer that I had on hand, I sure as heck wouldn't bother driving several miles just to buy a thicker crush washer. That's SO OCPD IMHO.
If there are too many crush washers, then the thread engagement of the banjo bolt in the caliper will be inadequate, and this could be considered unsafe. However, we don't have much information (measurements), so it is difficult to conclude on this topic.
If there are too many crush washers, then the thread engagement of the banjo bolt in the caliper will be inadequate, and this could be considered unsafe.
Totally agree. I was only suggesting the use of one additional copper crush washer for a total of three... not seven.
My roommate is very insistent that we simply over tightened the banjo bolt and now the soft brass of it is squished. I don't buy it but I'll humor him. He could use a good humbling anyway. Regardless I need to get more washers, so to the hardware store it is!
Distance from caliper to banjo bolt head HAND TIGHT: 0.469 in
Length of entire assembly (two washers + brake hose) HAND TIGHT: 0.541
This is with the thickest washers a guy could get his mitts on
My roommate finds it imperative that I unleash onto you a barrage of photos of the caliper threads that he took. Do you guys need to see more angles of the threads?
[This message has been edited by Doggo (edited 08-20-2024).]
Doggo: This is with the thickest washers a guy could get his mitts on / Do you guys need to see more angles of the threads?
0.072-inch isn't a lot of 'Squeeze' area, and I believe that the banjo bolt threads on TFS caliper are 'okay' but maybe not deep enough.
TO ME - I need more information by measuring the banjo bolt thread engagement. 'Measure' the banjo bolt from the bottom of the banjo bolt head to the end. By subtracting this length from the "Distance from caliper to banjo bolt head HAND TIGHT: 0.469 inch" gets you the "banjo bolt thread engagement".
Consider Your Options: *Add a Crush Washer {meaning three} as the peanut gallery suggests. *Run a bottom tap in the caliper to cut more threads BUT I worry about metal chips "on the car". *Shorten the end of the banjo bolt if you have enough banjo bolt thread engagement.
Your Call
{EDIT} NO, I DIDN'T "bless" Patrick's idea posted below....he is really pushing hard on this shade tree mechanic "solution"
quote
Patrick: Since the OCPD among us has now given his blessing, go ahead and use a third copper crush washer on each caliper.
[This message has been edited by Vintage-Nut (edited 08-21-2024).]
Distance from caliper to banjo bolt head HAND TIGHT: 0.469 in
Length of entire assembly (two washers + brake hose) HAND TIGHT: 0.541
This is with the thickest washers a guy could get his mitts on.
Since the OCPD among us has now given his blessing, go ahead and use a third copper crush washer on each caliper. Just make sure that all washers are either brand new (never been crushed), or if they're used copper crush washers, that they have been annealed.
By the way, in case you're running short of crush washers... the copper ones can be re-used after they've been heated red hot with a propane torch and then allowed to cool.
... but I seem to recall someone having an issue with the banjo bolt leaking no matter how tight it was... and it turned out it was due to the bolt itself bottoming out in the caliper before it was tight against the brake hose fitting. This was due to either the new brake hose fitting being narrower or the banjo bolt being a bit longer. Whatever it was, the solution was to use three washers instead of two.
Promise!
