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| Destroying my brand new caliper (Page 1/6) |
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Doggo
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AUG 19, 10:39 PM
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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).]
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IMSA GT
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AUG 19, 11:25 PM
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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).]
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Vintage-Nut
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AUG 19, 11:56 PM
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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.
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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......
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Original Owner of a Silver '88 GT
Under 'Production Refurbishment' @ 136k Miles
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cvxjet
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AUG 20, 12:00 AM
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cartercarbaficionado
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AUG 20, 12:05 AM
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| quote | Originally posted by Doggo:
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
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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).]
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Doggo
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AUG 20, 12:28 AM
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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).]
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Doggo
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AUG 20, 12:31 AM
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| quote | Originally posted by cartercarbaficionado:
if you need another is to try rock auto because they are only 50 there
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So it doesn't matter if each of the rear calipers are different?
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Patrick
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AUG 20, 01:16 AM
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| quote | Originally posted by Doggo:
...the caliper was leaking heavily from the banjo bolt.
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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).]
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cartercarbaficionado
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AUG 20, 05:04 AM
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| quote | Originally posted by Doggo:
So it doesn't matter if each of the rear calipers are different? |
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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
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Vintage-Nut
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AUG 20, 09:21 AM
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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.....
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Original Owner of a Silver '88 GT
Under 'Production Refurbishment' @ 136k Miles
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