tomekzxr Posted May 23, 2014 Report Share Posted May 23, 2014 I mean bolts made of 7075 alloy as pro bolt makes. Where is it safe to use them and where steel is a must. I want answear from someone with real engineering knowledge of stress calculations or people who used them somwhere else than obvious non stressed applications. 7075 takes stresses similiar to costruction steel from what I found in the tables. But since most of the bolts on the bike are mounted in soft cast aluminium, I imagine that very often the limiting factor for bolt diamter choice is thread durabilty on cast part side not the bolt itself. Then, would it be safe to use 7075 as ie. crimp bolt on yokes and fork bottoms,radial caliper bolts, rear subframe fitting, rearsets ? Link to comment Share on other sites More sharing options...
Superdunc Posted May 23, 2014 Report Share Posted May 23, 2014 7075 -T6 has a yield strength of 65,000psi, a grade 10.8 bolt is around double that.Also Aluminium is much more sensitive to stress raisers, and is much more susceptible to fatigue failures.If you screw a steel bolt into a aluminium casting, you are using the root of the thread to take the load, the area of which is larger than the cross sectional area of the bolt.I would not dream of using Alloy bolts in any of the applications you mention. Link to comment Share on other sites More sharing options...
Guest Posted May 23, 2014 Report Share Posted May 23, 2014 As Dunc has said, steel in stress applications, Ali if you must for fairing bolts etc, however I still use stainless steel or titanium as the Ali ones just seize, snap, and round too easily. Link to comment Share on other sites More sharing options...
Marb Posted May 23, 2014 Report Share Posted May 23, 2014 Alu only for non-fatal aplications. Ie, if they fail, it isn't fatal. Link to comment Share on other sites More sharing options...
tomekzxr Posted May 23, 2014 Author Report Share Posted May 23, 2014 Ok, thank all of You Link to comment Share on other sites More sharing options...
Guest Posted May 23, 2014 Report Share Posted May 23, 2014 I'd imagine that some of the torque settings for the applications you mention might have Aluminium bolt heads straight off. Link to comment Share on other sites More sharing options...
lorenzo Posted May 23, 2014 Report Share Posted May 23, 2014 I'd imagine that some of the torque settings for the applications you mention might have Aluminium bolt heads straight off. Some, yes, but the pinch bolts for fork bottoms always struck me as being really quite low. Link to comment Share on other sites More sharing options...
marcaztls Posted May 23, 2014 Report Share Posted May 23, 2014 Yamaha uses alloy bolts to hold the subframes on on R1's. Link to comment Share on other sites More sharing options...
blow_away Posted May 23, 2014 Report Share Posted May 23, 2014 A simple rule of thumb that I go by is A steel bolt should have twice its diameter as thread engagement, I.e. a M8 screw should have a thread depth of 16mm. For aluminium, increase this to 3 times the diameter. I know it's not entirely scientific, but neither am I ;-) Link to comment Share on other sites More sharing options...
owene Posted May 23, 2014 Report Share Posted May 23, 2014 When I started designing bits for engines, the guidelines for steel bolts were 2x minimum thread engagement in aluminium, 1.5x for cast iron, and 1x for steel, and I still use those numbers. Never used or specified aluminium bolts, but given the fatigue problems associated with ali, I'd go along with the non-critical comments above. Link to comment Share on other sites More sharing options...
Superdunc Posted May 23, 2014 Report Share Posted May 23, 2014 Yamaha uses alloy bolts to hold the subframes on on R1's......and use an appropriate size bolt. If a bike runs an M8 steel bolt, for a subframe mount I wouldn't recommend someone replacing it with an Alloy M8. Link to comment Share on other sites More sharing options...
marcaztls Posted May 23, 2014 Report Share Posted May 23, 2014 Yep, it's M10 that Yam use in that area. Link to comment Share on other sites More sharing options...
tomekzxr Posted May 25, 2014 Author Report Share Posted May 25, 2014 But my R1 has oem steel bolts for subframe. M10 fine pitch it is. Link to comment Share on other sites More sharing options...
marcaztls Posted May 25, 2014 Report Share Posted May 25, 2014 What year is your R1? Link to comment Share on other sites More sharing options...
tomekzxr Posted May 26, 2014 Author Report Share Posted May 26, 2014 2009 early woobly Link to comment Share on other sites More sharing options...
marcaztls Posted May 26, 2014 Report Share Posted May 26, 2014 Yes, yours are steel. However some earlier models of R1, and I believe some R6's too but without being at work to check, used alloy M1x1.00 bolts. Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.