diff --git a/MuonSpectrometer/MuonDetDescr/MuonReadoutGeometry/src/MMReadoutElement.cxx b/MuonSpectrometer/MuonDetDescr/MuonReadoutGeometry/src/MMReadoutElement.cxx
index ff09a3cee4aa8b7b9622ef5546fe29a71a2e7bd7..d21d212ddca89cec390d8525a86ce3361af0e5b3 100644
--- a/MuonSpectrometer/MuonDetDescr/MuonReadoutGeometry/src/MMReadoutElement.cxx
+++ b/MuonSpectrometer/MuonDetDescr/MuonReadoutGeometry/src/MMReadoutElement.cxx
@@ -283,19 +283,16 @@ namespace MuonGM {
       // identifier of the first channel
       Identifier id = manager()->mmIdHelper()->channelID(getStationName(),getStationEta(),getStationPhi(),m_ml, layer+1, 1);
 
-      // move the readout plane to the sensitive volume boundary 
-      double shift = 0.5*m_etaDesign[layer].thickness;
-      double rox = ( layer==0 || layer==2) ? shift : -shift;
-      
+      // keep the tracking surface at the center of the gap
       // need to operate switch x<->z because of GeoTrd definition
       m_surfaceData->m_layerSurfaces.push_back( new Trk::PlaneSurface(*this, id) );
-      m_surfaceData->m_layerTransforms.push_back(absTransform()*m_Xlg[layer]*Amg::Translation3D(rox,0.,0.)*
+      m_surfaceData->m_layerTransforms.push_back(absTransform()*m_Xlg[layer]*
 						 Amg::AngleAxis3D(-90.*CLHEP::deg,Amg::Vector3D(0.,1.,0.)) );
 
       // surface info (center, normal) 
       m_surfaceData->m_layerCenters.push_back(m_surfaceData->m_layerTransforms.back().translation());
       m_surfaceData->m_layerNormals.push_back(m_surfaceData->m_layerTransforms.back().linear()*Amg::Vector3D(0.,0.,-1.));
-      // get phi direction of MM eta strip 
+
 #ifndef NDEBUG
       double sAngle = m_etaDesign[layer].sAngle;
       if (log.level()<=MSG::DEBUG) log << MSG::DEBUG <<"MMReadoutElement layer " << layer << " sAngle " << sAngle << " phi direction MM eta strip " << (m_surfaceData->m_layerTransforms.back().linear()*Amg::Vector3D(0.,1.,0.)).phi() << endmsg;