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| Starter Ring Gear Location | Rating: 
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| Posted: 01-10-2007 07:21 pm |
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1st Post |
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Dave Sollish Member
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I am trying to troubleshoot a starting problem and I need to know the dimension from the starter mounting flange to the ring gear. I would like to tell if the ring gear has shifted aft without having to pull the transmission. On my engine the ring gear forward face is 1.54" from the starter mounting flange.
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| Posted: 01-14-2007 01:49 am |
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2nd Post |
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Dan Eiland Member
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The flywheel that holds the ring gear has a small lip around it to keep the ring gear from moving back as the starter gear kicks forward and engages the ring gear. I was at the machine shop just yesterday checking on some aluminum flywheels I'm having made and we found the ring gear on one of my original flywheels was mounted backwards. It seems the OE ring gears are one directional. The teeth have been beveled on one side which is to face the starter gear. The backside of the OE ring gear is straight cut--no bevel. The bevel should work like a synchronizer so the starter gear does not damage the ring gear when they engage each other. As the starter gear kicks forward it will first hit the beveled area of the ring gear pushing the ring gear/flywheel in the correct direction to the start the engine. As the flywheel moves just enough the starter gear and ring gear will, at just the right moment align and fully engage so the starter can start the engine. It could be the ring gear is not seated all the way back against the lip or it may be mounted backwards as was the case with mine. Sorry but I do not have any of the measurements.
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| Posted: 01-17-2007 03:05 pm |
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3rd Post |
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Dave Sollish Member
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This is a photo of the ring gear thru the starter hole. Is this the correct position or should the gear be further forward? Attachment: ring gear copy_edited-1.jpg (Downloaded 156 times)
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| Posted: 01-17-2007 10:17 pm |
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4th Post |
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Greg Fletcher Administrator 
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It's looks about right to me, but I don't have an old flywheel nearby to confirm either. You didn't say what the problem was, so I'll assume you have an intermittent starting problem? Typically what happens is that the ring gear get pushed slightly backward over the years (there's no shoulder for it to press against- what a lame design) so it's out of position in one spot. This could be hard to see without actually removing it. Whenever that spot meets the starter, the problem arises. When the problem first occurs it may be weeks or months before you see it again and as time goes on it becomes more frequent. Good idea to have the ring gear spot welded to the flywheel if doing a clutch or engine job. That's an annoying repair on its own! Have you checked out the starter solenoid? That tends to be the first thing that fails with the starter.
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| Posted: 01-18-2007 02:25 am |
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5th Post |
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Dan Eiland Member
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The ring gear is mounted correctly from what I can tell. You can plainly see the beveled edge I was refering to that should be facing the starter. The other side of my ring gear does not have this beveled edge which indicates to me it is not reversible. Based on my observations of the ring gear off my car it also looks like there is a small angle build into the teeth. If you reverse the ring gear and re-install it, the teeth would be at the wrong angle to engage the starter. Between the angle of the teeth being off and the teeth not being beveled adds up to bad news if someone reverses the ring gear on a Jensen Healey. Like Greg has already pointed out, I do not see where you have identified or explained exactly what kind of starting problem you are having. Could you tell us more about your starting problem? Maybe it's just not getting enough coffee in the morning? Or, maybe the coffee isn't strong enough?
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| Posted: 01-18-2007 11:10 am |
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6th Post |
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normv Member 
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I don’t have a flywheel handy but it is easy to work it out, Measure from the starter mounting face on the block to the ring gear then from the face on the starter to the inside of the alloy nose of the starter ( the limit of where the pinion can travel to) If these measurements are close there is your problem, the distance from the block to the ring gear needs to be less by roughly the thickness of the ring gear to allow the pinion to mesh well with the ring gear. I hope this makes sense.
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| Posted: 01-18-2007 05:02 pm |
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7th Post |
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Dave Sollish Member
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I replaced the starter about 1 year ago with a high torque aftermarket one from Gustafson Machine Gear Reduction Starters. Prior to October it was working fine. Then it started to occasionally spin without cranking the engine. From the attached drwg you can see that even when fully engaged the pinion just barely makes contact. I rechecked the ring gear dimensions at several points and they all were about 1.53" to 1.55" from the bell housing to the front face of the gear. There is no visible damage to the gear teeth or obvious displacement. So either 1) the ring gear has shifted aft .250" all around or 2) the starter solenoid is not extending completely or 3) the starter needs to be mounted further aft. Attachment: Ring Gear Drwg.jpg (Downloaded 59 times)
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| Posted: 01-18-2007 05:15 pm |
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8th Post |
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Greg Fletcher Administrator
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I'd put the old starter back in and see how that goes. You made it sound like nothing was wrong with it. I'm not a big fan of the high torque starters myself. If the JH has no other problems, you don't need one. The original starter that came with the car is very well made and will last decades.
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| Posted: 01-19-2007 10:05 am |
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9th Post |
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normv Member
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Dave To get you a definitive answer on your problem I just pulled the starter motor out of one of my cars and the ring gear is about 1.32 in from the block face (the verniers were on a small angle but it should be within 0.02 , this is your 1.54 distance) the ring gear should sit up against the edge you point to in your original photo so yes yours has moved if there is a gap there. I have attached a photo of mine. Sorry looks like it is out with the gearbox. Attachment: ring gear.jpg (Downloaded 379 times) Last edited on 01-19-2007 10:14 am by normv |
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| Posted: 01-19-2007 02:37 pm |
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10th Post |
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Dave Sollish Member
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Thanks Norm, That provides the answer I needed! (Damm!!)
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| Posted: 04-29-2007 04:59 am |
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11th Post |
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Dave Sollish Member
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I am about to reinstall my flywheel with the new ring gear solidly welded on. However I just noticed looking at the photo that Normv posted that the chamfer on his gear is reversed from the chamfer on mine. I installed the new gear the same way the old one came off. The shop manual is not quite clear on this and I sure don't want to install this if it is wrong!!! Which way is the correct? My picture is posted 1/17 Norm's is posted 1/19
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| Posted: 05-24-2007 07:09 pm |
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12th Post |
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timeforwalkies Member
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REGARDING ALUMINUM FLYWHEELS: Is there a significant advantage? What is the cost and where do you get them? Delta seems to think that a modified steel unit is close in terms of weight and is functionally superiour.....comments? Does anybody have detail drawing of such a modification, steel or aluminum? And where would you get a ring gear? Just trying to learn, timeforwalkies Last edited on 05-24-2007 11:20 pm by timeforwalkies |
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| Posted: 05-24-2007 11:02 pm |
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13th Post |
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Jensen Healey Super Moderator 
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Steel flywheels are stock on a Lotus Esprit S3 Turbo. Check the usual Lotus suppliers. http://www.sportscarworld-lotus.com/ http://www.rdent.com/ http://www.jaeparts.com/ http://www.lotuseliteparts.bravepages.com/LotusEspritengine.html I have no idea how one might modify one or if that would be wise given that most of us like our ankles. Kurt
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| Posted: 05-25-2007 12:49 am |
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14th Post |
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Dan Eiland Member
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I had several Aluminum Flywheels made a few months back and they began with my original cast iron boat anchor for the design. The company that made them is a Tilton Dealer and they specialize in building racing parts and chassies. When I told them that Tilton used to make these they looked them up and used some of the specs from Tilton. I have one for my car and I also have a second one put away. Both of my aluminum flywheels weigh 7 pounds without the ring gear and just under 8 pounds with a ring gear. The ring gear from the stock JH fits right onto these flywheels so this isn't an issue. I had one of the flywheels balanced to my engine and the second one was neutrally balanced so it can be used with any JH engine. I also had some grub screws added to the flywheel I'm using on my engine to hold the ring gear in place so it will not move. I can always have more flywheels made if anyone is interested in one, but you would need to have your old ring gear mounted to it or you can purchase a new ring gear and send it to me and I can have it mounted to your new aluminum flywheel if you elect to have one made. You can also pick what weight you want your flywheel; you just need to let me know ahead of time. The flywheels are made on a CNC machine and the program has already been written since I already had some made. The last time I had them made they cost me $350 each plus balancing and surfacing. I think when it was all finished they cost around $450 plus shipping. Since my car is still under construction I can't tell you how well they work, but there are a couple of people out there who have one and maybe they could tell you. Have attached a photo of my spare. Attachment: Aluminum Flywheel 3.jpg (Downloaded 84 times)
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| Posted: 06-23-2007 10:03 am |
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15th Post |
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Jon Plowe Member
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This might be a dum question, but would an aluminium flywheel need a different clutch plate from standard (a certain type of friction material?) and would the mating surface wear out/get scored up far quicker than a steel one? As our cars don't tend to do that many miles and we seem to enjoy pulling them apart this might not be seen as a problem.Thanks Jon
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| Posted: 06-29-2007 01:03 am |
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16th Post |
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timeforwalkies Member
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Just had a thought regarding flywheels. My reason for considering an aluminum flywheel is primarily because my existing flywheel has a bad tooth ache. That and a heavy rotating mass is harder to move than a light one. Since I want to be able to have my wife drive the car I have decided in favor of the boat anchor. But after looking at my boat anchor, it seems resonable to just reverse the dowels. That would allow me to rotate the flywheel 180 degrees. Does anybody have an opinion on this? Seems resonable to me.
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| Posted: 04-27-2010 08:56 pm |
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17th Post |
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Steve88W Member 
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If the ring gear is supposed to be flush up against that seam, that would explain why my starter no longer engages the flywheel. Any chance I can gently tap this ring back into place temporarily so I can at least get the car running again? See photo below Attachment: JH_Flywheel.jpg (Downloaded 45 times)
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| Posted: 04-28-2010 02:18 pm |
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18th Post |
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Brett Gibson JH5 20497 Member
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Yes & Yes, you have nothing to lose. Brett
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| Posted: 11-30-2010 12:26 am |
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19th Post |
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timeforwalkies Member
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Have a new lighten flywheel. (EBAY). It looks to be new, but I am concerned that everybody, including me has a flywheel with a ring gear shrunk in place. Mine has the gears ground into the flywheel. Solves the slipping problem, but I am not positive that this is a correct flywheel. Has anybody ever seen a flywheel such as this. The part number on it is DA 21785 and 5F3N both cast into the flywheel. If somebody has a loose flywheel laying around, especially one with ground gears, I would appreciate it if you would verify my numbers. Thank you, TFW
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| Posted: 11-30-2010 01:41 pm |
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20th Post |
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Lash Russell Member 
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Hi Dave, I checked the flywheels I have and I have two with the DA21785 stamped on them with 20H2 and 26L4 after respectively. I have two others with 7199397 cast in. Mine are all extremely dirty and hard to 100% confirm if the ring gears are machined into the casting or pressed on bit it looked, at first inspection without solvent cleaning them, that they have ring gears slipped on because of the machined outer surface and what looks like a slight groove where the ring gear would sit into. Does anybody have insight as to why there are different casting numbers in the flywheels (DA21785 Vs. 7199397)? Hope this helps. Lash
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