Lotus Elan and Lotus Elan Plus 2 Forums

Broke another upper Thackeray spring washer the other day on the Weber DCOEs and went in to my spares and happened to notice I've got two different types. One of those is of very poor quality and can cause you grief like it has already for me. The good quality one is plated for corrosion protection, the end faces are parallel to each other for 7/8 of a full turn and the center winding has an offset kink just adjacient to each winding's end in diagonal transition area so the spring can collapse fully and not bind up. The poor quality one has no plating, the end faces are skew by an estimated average of about 15 degrees and less then half a turn on each face is anyway near parallel and the center winding has no kinks to allow the spring to fully collapse without binding up. In fact if they are installed to the normal preload they are binding in the diagonal transition area. This will just cause higher stresses in the spring and they will fail at a faster rate. Doesn't much help dampen the vibrations transmitted to the carbies either.

The crummy springs could be saved if both ends were ground back by about an 1/8" but don't remove the temper. Suggest you mount the top ones with the center winding transition facing up so you can see if there is any interferences and the bottom ones down so they can be viewed with a pocket mirror.

Please don't suggest using the really gimmicky rubber replacements grommets. They are about the worst thing you could possibly use to on a Weber. Do I need to explain why? Here's a hint, they cold flow (on the Elan actually hot flow) and have very poor what's called compression set and never stop doing it until they are extruded. They totally suck.
-Keith
p.s. Just found discovered the good ones have a problem also on about half the springs tested. Their wire ends ends foul the center transition diagonal area also just not as quickly as the junk ones and the spring will not collapse to be fully closed. I'm grinding mine back right now. What a pain! Please let me know if you've got a source for top quality ones.

wellll i have found simple split washers spread :huh: 1\8 th of an inch and used in pairs work just fine as i cant find thackery washers i had to improvise ed law

Perhaps you've been using counterfeit gimmicky rubber replacements grommets??

-John

Measured the spring loading at fully collapsed as 60 lbs on the good and the bad ones if that helps any... Going to investigate using bellevilles instead to possibly increase the time between faliures.
Best Regards,
-Keith

Looked for 5/16" ID Bellevilles which matched the strenght of the Thackeray washers and found there isn't anything close because they are all way to stiff. However there is an almost perfect match in a 1/4' ID one. Considering that the two bottom 5/16" studs are capable of constraining the Weber with five of the six degrees of freedoms and the top studs are just needed to provide the sixth constraint this will work no problem. Going to leave the Thackeray washers on the bottom studs since they don't break very often there. Need to find the specs predicting the fatigue lifetime for the Thackeray washer to compare the calculations. If there is no significant improvement to be gained I'll give it up.
-Keith

Looks like I've possibly stumbled upon a better spring then even a belleville to replace the problematic Thackeray washers. Just need to provide a smooth shank on the 5/16" studs for these springs ID's to slide on. I'll do a full engineering evaluation later.
<a href='http://www.cloverspring.com/cloverdome.htm' target='_blank'>http://www.cloverspring.com/cloverdome.htm</a>
-Keith

Checked the radial clearance around the 5/16" top mounting stud area on the Weber DCOE carbie body today. There's enough space to use two of the Cloverdome # 016100 spring washers in lieu of the Thackeray ones. First a special washer which has a proud 3/8" OD boss that sticks out sligthly more then the thickness of two Cloverdome springs. Then the washer stacked so the loads does not doulbe but the range of motion does. Then the 5/16" nut which needs to have a 3/8" +.010" ID counterbore deep enough so the special washer's boss can travel into that counterbore and allow the motion. So far so good. Okay, it's time to call the engineering staff at Cloverspring to see if these springs will last many times longer in fatigue then a Thackeray washer or not.
-Keith

Chatted with the application engineer at CloverSpring today. Of course the sizes which will possibly work on the Webers are not available yet. He stated they should be in production by December of this year. I'll just have to wait till then and see how this plays out. In the meantime they are going to quote me 100pcs made with a wire EDM process. Bet I can't afford those. Normal production method is they are punched from a sheet.
-Keith

Had the CloverSpring sales rep call me this morning. The cost of the 100 custom pieces would be several thousand dollars. I declined to place an order. Explained what I wanted to do with these spring washers to solve the breakage of the Thackeray washers. As a result he put us (Weber nuts) on the priority list to have the size needed put into production on a ASAP basis. I'm to be notified as soon they are available and supplied with samples for testing. This solution still looks promising!
-Keith