Axle rebuild help. How badly did I screw up? (1 Viewer)

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Jan 7, 2009
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Even with labeling things I accidently installed the brake caliper bolts in the trunion bearing cap. I realized it right after I did it but I was at a good stopping point. Did I do any damage? This is pretty much my first time to ever work on anything!
 
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They are both 17mm head, aren't they? Check closely the bolts, knuckle threads and the bearing cap for damages. You should be fine if there's no damages. Get a hold of some one who has done this before or read up on it a lot before you start and as you do the procedures, double + tripple check every thing. Take your time before moving on to the next step. :cheers:
 
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There the exact same. I'm the most unorganized person in thhe world, i lost a bearing cap bolt, and had an extra caliper bolt laying around, and used it. Been offroad a couple times since then, and everythings fine
 
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When I put them in they didn't go in as smoothly as I thought they should. I backed them out several times to make sure the threads weren't damaged. They weren't. I should have checked then. I think they might be identical bolts. I think I will swap them anyway.
 
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96cruiser, thanks for confirming they are the same bolts. I will just leave it alone. Everything else so far has been very straight forward. It's looking like I might not have to have it towed to someone who knows what they are doing! Ha!
 
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Im in the middle of a axle rebuilt, and from what I could remember, they are the same size bolts but different grades. If you check top of the bolt, the trunion bearing cap bolt is more flush, and the brake caliper bolt has a small lip all around the edge of the bolt. Again, im going off memory.
 
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Just for peace of mind, you may want to check the part numbers of the two bolts. If they're the same, you're good to go. Beware though, I don't know if Toyota is anal and gives different part numbers to the same bolts like some other manufacturer's do.
 
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Well, I think I will just go ahead and take them out and put the original ones in. I worry too much as it is and I just put the knuckle back on so it won't be that much work to swap them at all.
 

cruiserdan

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The part numbers are not the same.

The caliper bolts are a higher strength than the trunion cap bolts. I would switch them back and inspect the holes and bolts for thread damage since the pitch is also different.



:EDITED TO ADD THE DIFFERENCE IN THREAD PITCH
 
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Thanks CruiserDan. I will switch them back. Thanks for the complete parts kit too.
 

simps80

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they're not the same!!!

the caliper bolts and the trunnion cap bolts are not the same

they are both 12mm bolts (17mm) on the head

thread pitch is 1.25 on the calier bolts
1.5 on the trunnion cap bolts...

how do I know?

I just did this same thing....sucks

the right hand side when I took it apart I noticed they were very similar to I screwed the caliper bolts back into the housing so I wouldn't get confused on re-assembly, however I hurried through the driver side and un reassembly, screwed the caliper bolts into the trunnion cap/housing holes.....

what I did to resovle it:
1. chase threads in knuckle for trunnion cap with 12mm x 1.5 thread pitch tap, CAREFULLY

I ruined the caliper bolts got new ones

I ruined the trunnion cap bolts after attempting to screw them in prior to chasing threads w/ tap.

so I would get new bolts if they're boogered up at all

now for the holes, cruiserDan and ben at slee (thanks to both btw) if you can clean them up w/ a tap good enough to get the new bolts to torque down to the 71 ft lbs and there are enough clean threads to equal the width of the bolt, it should be good.

As Dan pointed out, there is not a lot of DOWNWARD force on the top of the knuckle, but there is some significant lateral forces.

So...to make the width of the bolt to depth of the threads point more clearly:
the bolt is 12mm wide, if there are 12mm or more worth of good clean threads in the hole that the bolt can grip, and again if it torques to spec w/o pulling threads, its probably good.

if not...I don't think i'd tap that housing and drill the cap, I would buy a new housing (which Dan told me when I called) he stocks, not for this particular mistake, but the more common mistake of pulling the threads out of the caliper holes....

anyway,
I feel your pain, just did this this week, lots of stress and heartache, but at the end of the day, on the bench I cleaned up the holes w/ a tap and torqued (and retorqued) the trunnion cap to spec and its holding up fine so far...

I beat on it pretty good on Sunday on the first run for the vehicle at Johnny Park Road...lots of fun, and it held up fine.
 
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Ok. Good information.

I haven't installed the trunion bolts in the caliper so I won't have a problem with the caliper.

I have never used a tap.

Just line it up and screw it in the knuckle and then back out?

Should I go ahead and order new caliper bolts since I screwed them into the knuckle?
 

simps80

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my caliper bolts were ruined after screwing them into the trunnion cap holes...

depends on how far you got into the housing, and how much resistance/heat built up...

stupidly, I had built up enough heat/resistance by screwing the wrong bolt it, it actually started to melt the first few threads...

so yea I replaced those bolts...

then after trying to 'chase the threads' with the right trunnion bolts I ruined those too...

as far as the tap is concerned
I took it off the truck, put it in the vise so I knew it was square and used the tap with the the 2 handles to make sure I was screwing it in nice and straight,

screwed it in a little, backed it out, blew the hole out w/ brake cleaner,

tiny bit of cutting oil, back in with the tap, little farther, backed out,

you'll get a feel for how much its cutting based on resistance and if/how much shavings are coming out when backing the tap out.

by the end of it, I had screwed the tap in and back out probably a dozen or so times, starting first with a few turns at a time.

eventually i got the tap all the way through the hole with little resistance and a good tight fit, there were parts of some threads missing, but the bottom portion of the hole was clean threads, and the top were clean and they all lined up...

so...blow out the holes w/ brake cleaner as you go, use a little wire brush to clear out the metal out of the hole as you go

whatever, you'll get the feel, make sure the tap is square to the hole, and take your time, don't try and tap it all at once, back in back out, in a little further bakc out, in a little further, back out etc. w/ cleaning in between.
 
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Well I am glad I asked about this.

I already packed the knuckle with fresh grease. I guess I have to clean all of that out again. Fun stuff.

I think I will buy a "thread chaser" at Sears. As I understand that will cut less and clean up more than anything.
 
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How bad would it be to leave the caliper bolts that are torqued down to spec in the trunion until my next rebuild?

I am doing this at a friends house and I really don't want to overstay my welcome. I would just order new caliper bolts and then fix it properly when I buy a house this summer.
 

simps80

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yea i thought about a "thread chaser"
but i boogered up the holes too bad,
at least the top 5 threads needed re-cut
to even get the right bolt in there.

as far as run it w/ the caliper bolts...
I can't comment on that

I could but not authoritatively by any stretch of the imagination.
 
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Jan 7, 2009
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I understand.

Wrong bolts are wrong bolts and it's hard to say anything about it.

I think I will try it and just lift it up every couple of days and check it.

They torqued down to 71ft/lbs as they should.

They are stronger than the trunion bolts as well.
 
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Interesting that over the years we've had a few folks have issues with their front caliper bolts coming loose. Makes me wonder how common it is to mix these up, and it this mixup is the source of those issues? A slight thread pitch difference would do it. Maybe this should go in the front axle writeups/FAQs.

DougM
 
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I wouldn't be surprised if several people have switched them. I am going to run caliper bolts in the trunion for a couple of months. I think it will be fine. I will never make this mistake again I know that.
 

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