jamesvfr Posted September 8, 2009 Share Posted September 8, 2009 Hi all, just made a winch bumper for my rangie +wondering what type of bolt to use to mount it The last thing i want is for it to snap te bolts + pull of Cheers James Quote Link to comment Share on other sites More sharing options...
zardos Posted September 9, 2009 Share Posted September 9, 2009 Hi all, just made a winch bumper for my rangie +wondering what type of bolt to use to mount it The last thing i want is for it to snap te bolts + pull of Cheers James Not a Ranjie but for a Defender most winch bumpers use the standard bolts which are 4 of M10 X 130mm DIN931 Grade 8.8 (vertical through the chassis) + 2 others horizontal through the chassis that look the same size an type. You could go to Grade 12.9 for extra strength but these are usually Allen Key drive and usually not cheap and my local specialist supplier (http://www.orbitalfasteners.co.uk/) does do them long enough. Quote Link to comment Share on other sites More sharing options...
clbarclay Posted September 9, 2009 Share Posted September 9, 2009 I've seen a few bumpers held on by 4 M10 bolts, but the holes in the range rover chassis are big enough to take M12 bolts and the cost differance is only a few pence. I also extended the winch mounting brackets on mine back to existing mounting points on the chassis behind the cross member, using the existing 1/2" bolt holding the panhard rod bracket and adding another M12 on the other side. Its a lot more than some comercial bumpers get with, but unlike some it doesn't move either Just as important as bolt side is how well the brackets on the bumper fit against the chassis. The sides of the bolts should not push agisnt the sides of the wholes through the chassis or bumper. Instead the bolts should only clamp the bumper against the chassis and the bumper is the held inplace by friction. The tolerances on both chassis and comercial bumpers means that there can be a considerable gap between the bumper brackets and chassis and the bolts are not able to clamp the bumper properly, if this is the case then adding shims to fill the gaps between chassis and bumper will be far more effective than just using bigger/stronger bolts. If the bumper can move becasue it isn't clamped properly then the chassis, bolts and bumper will be damaged by the movement. I know one friends bumper you could grab the A bar and shake it by hand Assuming the bumper fits the chassis properly then common grade 8.8 (or imperial equiverlant) bolts should be sufficent and it the bumper doesn't fit properly then a 12.9 will be able to apply move force to clamp the brackets against the chassis, but thats a bodge and not correcting the problem. Quote Link to comment Share on other sites More sharing options...
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