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#1
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Torque converter bolts loosening over time ???
Any idea of what would cause torque converter bolts to begin loosening over time. Using an Art Carr 10-inch torque converter, a B&M flex plate and ARP bolts. Everything torqued properly and using Loc-Tite high strength thread locking compound. The bolts still get loose after a few weeks of daily use. Ideas ?
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#2
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You have
Done it all right. The only thing I can think of is a vibration that you can't feel inside the car.
My bolts came with serrated lock washers, which I did not use. I used blue loctite, and no problems in two years. Might try those washers and see what happens. |
#3
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I haven't had an issue with loose bolts, but have had vibration issues. The other thing I have found (B&M flexplate w/stock reman converter) is that the small dia. bolt holes in the flex plate did not line up with the converter. There are 2 sets of holes - the ones that lined up with the small-block converter were a size too big for the replacement bolts, but I had no choice but to continue the assembly. (I used ARP bolts also) I don't know why this is, but it might be something to look at. I used red Loctite last time, blue the first time.
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#4
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beldarchalcuda hear did you have the problem with the bolts coming loose before you changed the convertor if it was ok the convertor has to be the problem have you checked the depth of the bolt holes even though they are torqueing to specs are the bolts bottoming out in the holes you may have to use a bottom tap do not break it off it would only take one bolt not being tight to allow the other bolts to start comeing loose i have seen this before not on a convertor but in other engine problems hope this helps
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#5
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beldarchalcuda has a good point. I've seen TSB's for that exact problem. The bolts being too long can actually dimple the converter and if it's a lock up converter that's where the clutch surface is. Dimpling the converter can cause a lock up converter to slip. Definately worth checking out.
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#6
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I've had 3 different TC's in the car (running different stall speeds) and 2 flex plates (the 1st was ruined when I didn't catch the loose bolt syndrome in time). The problem has remained a constant throughout the entire time.
I'm thinking I must have some cyclic engine vibration that I can't feel. Maybe I'll have to try some kind of lock washers ? |
#7
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Are you using the correct bolts? They are supposed to have oversized heads.
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#8
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trans
Quote:
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#9
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.
Are you using the correct bolts? They are supposed to have oversized heads. . Pic of the bolt head : . |
#10
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Quote:
Using high strength 'Thread Locker Red'. |
#11
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If it were me I would take and run one of your bolt into a converter without the flex plate and see if there is excessive clearence between the bolt and converter with the bolt bottomed in the hole. Maybe they are just too long.
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#12
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Yep, those look good to me.
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#13
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Too long or too short can cause a problem. They can have problems, if they have been stretched.
Worst case, contact ARP and see what they think. I'm sure that they could come up with a solution. |
#14
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In an effort to keep this thread on topic, I have removed all traces of the argument. Please don't bring it back.
MOD |
#15
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...... But seriously, they still sell convertors with either 7/16 or 3/8 bolts; Maybe you got a 7/16 flexplate and trying to use 3/8 bolts? Also are you using a small snout convertor, like pre 67? If your trans bell is not indexed perfectly you could be slightly offset with the smaller convertor snout not piloting concentrically (sp?) , I broke 2 flexplates before I realized they need a bushing to be used in later cranks. You have access to a machine shop that can cut a shoulder in those bolts, that'll center them good and square, but there's not much meat on those. How about a small bushing in there? IF its a neutral flexplate, you can get it redrilled for the proper bolt size. Just thinking outloud.
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#16
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I have followed some threads on this subject in other forums and all of the points touched on here were tried with no success and no explanation of why it was occuring.
My suggestion was to drill the bolts for safety wire. |
#17
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I wonder
If the bolts are heat treated to a hardness that could negate drilling for safety wire. I'm thinking that they are too hard.
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#18
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Another thought
Set the B&M flex plate on a granite table and check for flatness. First observe the larger diameter sitting on the table. Is it in full contact?
Now run an indicator across the top side. What is the value? |
#19
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Yes, I have heard the same thing. This has been going on for over ten years. Through 3 different TC's, 2 different flex plates, and a couple sets of bolts. I'm stymied. At this point it seems as though it must be something other than the hardware I've mentioned (since everything has been switched around and I still get loose bolts).
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#20
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And your torquing the bolts to 25 ft lbs?
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#21
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I like the safety wire idea. Done right, the bolts will not back out. We used safety wire on almost every bolt, when I was working on B-52 bombers. I never found a loose bolt.
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#22
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You'll have to find a machine shop to drill the bolt heads for wire. A carbide bit will drill that material, but it'll take a fixture and a drill press or Bridgeport machine to do the job.
There are also locking tab washers that have a small tab that can engage a small hole on the part, and then have a flap that can be bent around the head of the bolt. They work pretty good. Sorry I can't find a real good picture of these, but this will give you an idea: |
#23
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Sheaa, those look like pretty good pics to me! Cut my teeth on VersaCad back in the day and spent plenty of hours over a drafting table with those metal pencils and the twirly sharpeners. I was going to suggest tacking them with a stick welder on a small spot, then you can just tap it off with a chisel when you are ready to loosen it.
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#24
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I bet that the dowel pin locations are off. The crank center line isn't in line with the tranny center line. Offset dowel pins are used to correct this. The bad thing is you have to disassemble the auto trans to check this out. Factory machining tolerances have been known to be quite a few thou off at times.
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#25
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Yes, at first to 25, then later to 28 ft lbs.
Quote:
. |
#26
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What engine is this...........
being used on? Is the engine internally balance or external? Does the converter have any weights on it. Does the flex plate have any weights on it?
Sounds like a mis-match in weight to me. I know these are simple questions that most people would ask but it sounds like you have done everything to fix the problem. The real problem comes from somewhere other than the bolts, as you have already replaced the bolts with another set. Sorry, just thinking out loud. |
#27
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I have the same trouble but have not looked into to much. My specs are 440 .040 over steel crank stock rods TRW slugs ( NO AFTERMARKET balance job done ) fluid dampner Dynamic converter mopar sfi flex plate and arp bolts. However I do have a midplate and lost the crank shim so I cut the center out of a old flex plate . !st no lock tite then blue and now the red . Have not run it after the red so hope that dose the trick.
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