function sp_f(form)
{
	   form.Sp1.value = Math.round((Math.round(form.Wdn.options[form.Wdn.selectedIndex].value*form.Hdn.options[form.Hdn.selectedIndex].value*2
      +form.Rdn.options[form.Rdn.selectedIndex].value*25.4)
      /Math.round(form.Wd.options[form.Wd.selectedIndex].value*form.Hd.options[form.Hd.selectedIndex].value*2
      +form.Rd.options[form.Rd.selectedIndex].value*25.4))*form.Sp.value*10)/10;
      form.Sp2.value = Math.round((form.Sp1.value-form.Sp.value)*10)/10
}

function t_calc(form)
{
   <!--   alert(form);-->
      form.Tw.value = form.Wd.options[form.Wd.selectedIndex].value;
      form.Tw1.value = form.Wdn.options[form.Wdn.selectedIndex].value;
      var Tw2 = form.Wdn.options[form.Wdn.selectedIndex].value-form.Wd.options[form.Wd.selectedIndex].value;
			if (Tw2<0){$('Tw2').innerHTML=Tw2+' мм';}else{$('Tw2').innerHTML='+'+Tw2+' мм';}
      
      form.Tr.value = Math.round(form.Rd.options[form.Rd.selectedIndex].value*25.4);
      form.Tr1.value = Math.round(form.Rdn.options[form.Rdn.selectedIndex].value*25.4);
      var Tr2 = Math.round(form.Rdn.options[form.Rdn.selectedIndex].value*25.4)-Math.round(form.Rd.options[form.Rd.selectedIndex].value*25.4);
			if (Tr2<0){$('Tr2').innerHTML=Tr2+' мм';}else{$('Tr2').innerHTML='+'+Tr2+' мм';}
			
      form.Th.value = Math.round(form.Wd.options[form.Wd.selectedIndex].value*form.Hd.options[form.Hd.selectedIndex].value*2+form.Rd.options[form.Rd.selectedIndex].value*25.4);
      form.Th1.value = Math.round(form.Wdn.options[form.Wdn.selectedIndex].value*form.Hdn.options[form.Hdn.selectedIndex].value*2+form.Rdn.options[form.Rdn.selectedIndex].value*25.4);
      var Th2 = Math.round(form.Wdn.options[form.Wdn.selectedIndex].value*form.Hdn.options[form.Hdn.selectedIndex].value*2+form.Rdn.options[form.Rdn.selectedIndex].value*25.4)-Math.round(form.Wd.options[form.Wd.selectedIndex].value*form.Hd.options[form.Hd.selectedIndex].value*2+form.Rd.options[form.Rd.selectedIndex].value*25.4);
      	if (Th2<0){$('Th2').innerHTML=Th2+' мм';}else{$('Th2').innerHTML='+'+Th2+' мм';}
      	
      var Kl = (Math.round(form.Wdn.options[form.Wdn.selectedIndex].value*form.Hdn.options[form.Hdn.selectedIndex].value*2+form.Rdn.options[form.Rdn.selectedIndex].value*25.4)-Math.round(form.Wd.options[form.Wd.selectedIndex].value*form.Hd.options[form.Hd.selectedIndex].value*2+form.Rd.options[form.Rd.selectedIndex].value*25.4))/2;
			if (Kl<0){$('Kl').innerHTML='Изменение клиренса: '+Kl+' мм';}else{$('Kl').innerHTML='Изменение клиренса: +'+Kl+' мм';}
      
      	var koef=Math.round(form.Wdn.options[form.Wdn.selectedIndex].value*form.Hdn.options[form.Hdn.selectedIndex].value*2+form.Rdn.options[form.Rdn.selectedIndex].value*25.4)/Math.round(form.Wd.options[form.Wd.selectedIndex].value*form.Hd.options[form.Hd.selectedIndex].value*2+form.Rd.options[form.Rd.selectedIndex].value*25.4);

      $('speed60').innerHTML=Math.round(koef*60*10)/10;
      $('speed90').innerHTML=Math.round(koef*90*10)/10;
      $('speed100').innerHTML=Math.round(koef*100*10)/10;
    
		$('sp_raz_60').innerHTML=	Math.round((Math.round(koef*60*10)/10-60)*10)/10;
		$('sp_raz_90').innerHTML=	Math.round((Math.round(koef*90*10)/10-90)*10)/10;
		$('sp_raz_100').innerHTML=	Math.round((Math.round(koef*100*10)/10-100)*10)/10;
      
      form.Sp1.value =Math.round(koef*form.Sp.value*100)/100;
      form.Sp2.value = Math.round((form.Sp1.value-form.Sp.value)*100)/100
      
	}
<!-- done hiding from old browsers -->