faced with a problem. I worked out how to get around it. But since its brake related thought id get some second opinions before i do something unsafe. I bought a big brake kit, came with dogbone adapters. So caliper is attached to chassis or whatever by four M12 bolts. came with adapter fixed to dogbone. So i tried reusing the stock two bolts for the other holes. Same size, same pitch. Problem is when i was tightening it started easy, then got real tough. I thought i might be stripping the thread so took it all apart and sussed it out. The standard bolt is threaded along half its length. This bit threads fine into adapter and chassis. But as soon as the bolt reaches the unthreaded shank it starts to strip the internal thread on adapter and chassis. Both threads are really worn down now. What to do? Since with the adapter theres room for a nut and bolt i figured id get a smaller (M10) nut and bolt and just bolt the joint together real tight and use loctite on it. No threads holding it together, just the bolts. Worries are: just got bolts from bunnings. Do they need to be special high tensile bolts, done up with more than just two ring spanners? Is bolting a bad option? Do i need to redrill/thread it to like 14mm or something? It is holding the caliper to chassis so i imagine under braking there would be a fair bit of shear force on the bolt. Im confused as its standard bolts and calipers. Dont understand why the threaded section fits, then the shank doesnt, and stripped the thread. id appreciate any ideas. Preferably something DIY and prefer not to redrill/thread as im not confident with that. If i could just bolt it together, then take it to a shop to tighten properly, id be stoked. Only thing then is what kind of bolts to use..
I see no direct problem with using bolts/nuts assuming there is enough clearance, however wouldn't an m10 leaving a gap in a m12 hole? i'd drill out the threads and use an m12 bolt and nut. Also i wouldn't use bunnings bolts, go to a proper bolt shop and get some of the highest tensile bolts you can get (SAE 8.8 or above should do it), then some washers and/or loctite and she'll be right
i think the reason why it gets tight and ended up stripping is because they aren't mounted perfectly. did the rotors rotate freely once the adapter is on and caliper all mounted up? if not you'll destroy the rotors and pads in no time. your adapter might not be the same but it's to do with the contact area circled in black. basically where the hub mounts contact the adapter, that surface on the adapter is perfect but on the hub it isn't even. so the adapter sits on a slight angle which prevents the bolts going in straight. you need to file the caliper mounts on the hub down where those surfaces meet so it removes the excess from casting. once the mount surface is within tolerance all bolts should go in without issues.
Do NOT use M10 bolts. Use M12. Do it right, don't screw around with your brakes! Pictures of the threads please. Might only need a clean up with a tap. If you do buy new bolts get 8.8 high tensile as noted above.
thanks for quick replies guys. Ill try get some photos up. Only have a camera phone though. i suspected it just wasnt going in straight because of the weight of the calipers. But then i removed the caliper and dogbone, and tried screwing the bolt into each one. Same deal with all, the unthreaded section of bolt didnt fit into the hole, and caused the bolt to just spin in place, stripping the threads. I think what ill do is try get some proper steel bolts and nuts. Then strip the thread off completely and just have the bolts clamping it together. I dont have the tools for drilling/tapping. Any ideas where i can get these high tensile bolts? Hopefully somewhere transport accessible. So you guys say definately get 12mm again, and make the holes a bit bigger so it just slides in? No going down to 11mm to save stripping the hole out any more? (i realise theyre engineered to 12 for a reason).
mikez32: I noticed a bit of this at first. But adjusting the adapter let me fit it up properly. I couldnt actually get the bolts in enough to check fitment, the caliper was still loose. also to check if this was the cause, i tested the bolt in each hole seperately (off the car). n they didnt fit. Although this could likely be because of my initial thread damage? That sounds likely. Either way, threads stripped, ill try the bolt alternative to get my car back on the road. Next time ill be more careful
i'd say this was the case. once the thread is damaged it's too late. i tried fitting a set last year, passenger side went on ok but i couldn't get the driver's side on. before using brute force i took it off and checked if the screws would go in off the car. fits perfectly but refused to go in while on the car. can't take full credit for this, i rang tekky and he told me it's the surface on the hub mounts. sure enough the adapter was on a slight angle. only slightly off due to a nasty surface but this was all that prevented the screw going in straight. don't be messing around with the wrong size bolts though. brakes are one of those things that needs to be EXACT.
ok so i found a few websites that sell and deliver the bolts i need. So im gonna order some M12 high tensile ones and suited nuts and washers as well. One thing im wondering, with clearing out the damaged holes. I want to keep them relatively tight. So minimal tolerance. Whats the best way of stripping the thread out so the bolts slide in easily? continue tightening the old bolts in there atm until the threads smooth? This is the easiest way i can think of. Is it a valid approach? -buy grade 8.8 high tensile nuts and bolts. -strip hole thread completely with old bolt thats still halfway in there. -put the new bolts in. Hopefully they go in pretty easily with the new clearance. If its still too tight how do i make the hole bigger? Apart from drilling it. small file ok?
i need to grind the hub a bit, in order to fit the adaptors perfectly, otherwise i cant line them up.
ok ive been fiddling around with the calipers, dogbone and the various bolts i have. Im pretty sure ive worked out the situation. The stock bolts are threaded for about half the length, and straight shanked for the other half. The diameter of the shank bit is equal to the outer thread diameter. So the shank wonnt fit into an M12 thread. now with the dogbone to caliper hole (came already bolted together), the dogbone wasnt threaded, and caliper was. So they bolted fine together using this half shank- half thread bolt. However, the dogbone to hub holes are different. both parts were threaded, and didnt have any bolts with it. and i tried fitting with the stock half-half bolt. Thus when the shank part reached it wouldnt tighten any further, and started stripping thread. Two things could have been done. 1. Buy some new bolts, threaded along its entire length. 2. Drill out the thread on the dogbone, so its the same as the dogbone to caliper join. The shank section would fit fine then, and threaded bit secure to the hub. Ive filed off the threads on the dogbone, and the stock bolt fits in fine. In the morning ill check how the threads on the hub are. If theyre still good it should bolt up fine this time. If not, ill have to file the hub threads out too and use the new bolt and nut approach.
wait a sec, the hub is not threaded. the M12 bolt should go straight through the hub's hole and bolts to the dogbone. are you doing like this?
....... :'( hall of shame If thats the case lovic i hate myself. Caused 100 problems for myself out of nothing. I was under impression they were both threaded. If the hub isnt, im an idiot. Well....... I guess its too late and ive screwed myself. Gotta go get some high tensile bolts and nuts. the threads in the dogbones have been stripped pretty bad.
OMG LOL. you mean you tried installing it the wrong way? the hub is not threaded so you can only install it in the way pictured.
I had to clean up the cast flashing on the hubs and linish the dogboes a bit to get them to fit properly. You should get the dogbone thread recoiled to fix this NOT put nuts on the outside.
Suggest you take it down to UAS, JP could probably fix it. Dont know anywhere else up there to suggest.
Attila I'm feeling your pain, but what were my last words to you? When you are ready to fit them call me and i will come over and give you a hand to put them on and get them operating. For the record these were the UAS big brake kit as fitted to mine before i changed over to the Stop Techs, these were in good condition and working perfectly. All it needed was to be attached properly and every thing would have been fine, mate i was only a phone call away.
