diff --git a/solr/core/src/test/org/apache/solr/cloud/autoscaling/sim/SimCloudManager.java b/solr/core/src/test/org/apache/solr/cloud/autoscaling/sim/SimCloudManager.java
index a6d76c8cffc..dad946368bf 100644
--- a/solr/core/src/test/org/apache/solr/cloud/autoscaling/sim/SimCloudManager.java
+++ b/solr/core/src/test/org/apache/solr/cloud/autoscaling/sim/SimCloudManager.java
@@ -889,6 +889,7 @@ public class SimCloudManager implements SolrCloudManager {
     IOUtils.closeQuietly(stateManager);
     triggerThread.interrupt();
     IOUtils.closeQuietly(triggerThread);
+    triggerThread.interrupt();
     try {
       triggerThread.join();
     } catch (InterruptedException e) {
diff --git a/solr/core/src/test/org/apache/solr/cloud/autoscaling/sim/SimClusterStateProvider.java b/solr/core/src/test/org/apache/solr/cloud/autoscaling/sim/SimClusterStateProvider.java
index 930b761f1df..d81d92c75ed 100644
--- a/solr/core/src/test/org/apache/solr/cloud/autoscaling/sim/SimClusterStateProvider.java
+++ b/solr/core/src/test/org/apache/solr/cloud/autoscaling/sim/SimClusterStateProvider.java
@@ -1369,7 +1369,7 @@ public class SimClusterStateProvider implements ClusterStateProvider {
           OverseerCollectionMessageHandler.NUM_SLICES, "1",
           CommonAdminParams.WAIT_FOR_FINAL_STATE, "true");
       simCreateCollection(props, new NamedList());
-      CloudTestUtils.waitForState(cloudManager, CollectionAdminParams.SYSTEM_COLL, 90, TimeUnit.SECONDS,
+      CloudTestUtils.waitForState(cloudManager, CollectionAdminParams.SYSTEM_COLL, 120, TimeUnit.SECONDS,
           CloudTestUtils.clusterShape(1, Integer.parseInt(repFactor), false, true));
     } catch (Exception e) {
       throw new IOException(e);
diff --git a/solr/core/src/test/org/apache/solr/cloud/autoscaling/sim/TestSimLargeCluster.java b/solr/core/src/test/org/apache/solr/cloud/autoscaling/sim/TestSimLargeCluster.java
index e7a16e3c61f..bc4c598e40e 100644
--- a/solr/core/src/test/org/apache/solr/cloud/autoscaling/sim/TestSimLargeCluster.java
+++ b/solr/core/src/test/org/apache/solr/cloud/autoscaling/sim/TestSimLargeCluster.java
@@ -53,7 +53,6 @@ import org.apache.solr.cloud.autoscaling.TriggerListenerBase;
 import org.apache.solr.cloud.autoscaling.TriggerValidationException;
 import org.apache.solr.common.SolrInputDocument;
 import org.apache.solr.common.cloud.Replica;
-import org.apache.solr.common.params.CollectionAdminParams;
 import org.apache.solr.common.params.CollectionParams;
 import org.apache.solr.common.util.NamedList;
 import org.apache.solr.common.util.Pair;
@@ -78,7 +77,7 @@ public class TestSimLargeCluster extends SimSolrCloudTestCase {
   public static final int SPEED = 50;
 
   public static final int NUM_NODES = 100;
-
+ 
   static Map<String, List<CapturedEvent>> listenerEvents = new ConcurrentHashMap<>();
   static AtomicInteger triggerFinishedCount = new AtomicInteger();
   static AtomicInteger triggerStartedCount = new AtomicInteger();
@@ -133,12 +132,6 @@ public class TestSimLargeCluster extends SimSolrCloudTestCase {
       }
     }
 
-    // do this in advance if missing
-    if (!cluster.getSimClusterStateProvider().simListCollections().contains(CollectionAdminParams.SYSTEM_COLL)) {
-      cluster.getSimClusterStateProvider().createSystemCollection();
-      CloudTestUtils.waitForState(cluster, CollectionAdminParams.SYSTEM_COLL, 120, TimeUnit.SECONDS,
-          CloudTestUtils.clusterShape(1, 3, false, true));
-    }
   }
 
   public static class TestTriggerListener extends TriggerListenerBase {
@@ -310,7 +303,7 @@ public class TestSimLargeCluster extends SimSolrCloudTestCase {
     create.setAutoAddReplicas(false);
     create.process(solrClient);
 
-    log.info("Ready after " + CloudTestUtils.waitForState(cluster, collectionName, 20 * NUM_NODES, TimeUnit.SECONDS,
+    log.info("Ready after " + CloudTestUtils.waitForState(cluster, collectionName, 90 * NUM_NODES, TimeUnit.SECONDS,
         CloudTestUtils.clusterShape(NUM_NODES / 10, NUM_NODES / 8 * 3, false, true)) + " ms");
 
     // start adding nodes
@@ -325,7 +318,7 @@ public class TestSimLargeCluster extends SimSolrCloudTestCase {
     assertTrue("trigger did not fire", await);
 
     // wait until started == finished
-    TimeOut timeOut = new TimeOut(20 * waitForSeconds * NUM_NODES, TimeUnit.SECONDS, cluster.getTimeSource());
+    TimeOut timeOut = new TimeOut(45 * waitForSeconds * NUM_NODES, TimeUnit.SECONDS, cluster.getTimeSource());
     while (!timeOut.hasTimedOut()) {
       if (triggerStartedCount.get() == triggerFinishedCount.get()) {
         break;
@@ -510,7 +503,7 @@ public class TestSimLargeCluster extends SimSolrCloudTestCase {
     create.setAutoAddReplicas(false);
     create.process(solrClient);
 
-    log.info("Ready after " + CloudTestUtils.waitForState(cluster, collectionName, 30 * NUM_NODES, TimeUnit.SECONDS,
+    log.info("Ready after " + CloudTestUtils.waitForState(cluster, collectionName, 60 * NUM_NODES, TimeUnit.SECONDS,
         CloudTestUtils.clusterShape(NUM_NODES / 5, NUM_NODES / 10, false, true)) + " ms");
 
     // start killing nodes
@@ -701,12 +694,15 @@ public class TestSimLargeCluster extends SimSolrCloudTestCase {
     assertEquals(response.get("result").toString(), "success");
 
 
-    boolean await = triggerFinishedLatch.await(waitForSeconds * 20000 / SPEED, TimeUnit.MILLISECONDS);
+    boolean await = triggerFinishedLatch.await(waitForSeconds * 45000 / SPEED, TimeUnit.MILLISECONDS);
     assertTrue("The trigger did not fire at all", await);
     // wait for listener to capture the SUCCEEDED stage
-    cluster.getTimeSource().sleep(5000);
-    assertNotNull(listenerEvents.toString(), listenerEvents.get("srt"));
-    assertEquals(listenerEvents.toString(), 1, listenerEvents.get("srt").size());
+    cluster.getTimeSource().sleep(15000);
+    
+    assertNotNull(listenerEvents.entrySet().toString(), listenerEvents.get("srt"));
+
+    assertTrue(listenerEvents.toString(), listenerEvents.get("srt").size() >= 1);
+
     CapturedEvent ev = listenerEvents.get("srt").get(0);
     assertEquals(TriggerEventType.SEARCHRATE, ev.event.getEventType());
     Map<String, Number> m = (Map<String, Number>)ev.event.getProperty(SearchRateTrigger.HOT_NODES);