How bad is this - How to fix stripped threads

[Captinjack]

I have a chinese Kama 554 tractor that I recently noticed that a couple of bolts were loose. I tightened them and found out that they were loose again in a short time. After the third time, I removed the bolts and it appears that they are stripped of the threads and I'm also concerned that the female threads are stripped as well.

This is a picture of where they come from.

It's the bolts holding down the 3 pt. hitch tank. Only the two bolts closest to the top link are stripped. I'm guessing that upward forces from the back hoe and ground engagement implements has caused this problem.

Here is a picture of the two removed bolts.

And a closer up look at the worst threads.

I appears that some of the female threads came out with the bolts.

My question is.............How can I easily fix this? I know the tank would have to be removed to do it right, but I want to try some other easier fix first and do the good repair later when I MUST remove the tank for other reasons.

I'm thinking JB weld or red lock-tight or something like that. A heli-coil insert is what would be best, but I know there is someone out there that has been there before and would have some real life experience to help me out.

I don't know whether the female threads are closed off at the bottom or whether the theads are open and a longer bolt could "go thru" making bolt length less important.

I'm planning on buying new harder bolts and giving it a try the next time I get to visit my property.

Thanks in advance for any tips. I'm thick skinned so if I'm "peeing down my leg" thinking I'm getting warmer, don't hesitate to say that I'm SOL and will have to fix it right.

 

[ToadHill]

I would use a hyle-coil (sp) you use a drill, an oversized tap and with the tool that comes with the kit you insert the coil, brand new threads, usually a lot stronger than came on the equipment. The ones I used were stainless steel.

I used to use them on my race car anytime I stripped the threads out of a hole. In fact before I built a race engine, I put a coil in every threaded hole.

 

[ToadHill]

Second point, when you cut the new threads with the tap, if you grease up the tap and drill, it will hold the iron shavings and you shouldn't have to remove the unit.

 

[6sunset6]

Helicoil would be best. Next best , there are thread rebuild kits. Essentially epoxy that bonds to the walls and a release agent on a new bolt. Shove it all in there and let it cure. The bolt will release due to the release agent. Only issue is the hole must be absolulty clean .
I have used both and both work. Helicoil kits get expensive pretty quick.
Check McMaster Carr for Form A Thread and helicoils
Thinking more I would use a helicoil. Metric thread probably Mcmaster has them

 

[AndyMA]

Heli-Coil

Heli-Coil ( HeliCoil Inserts ) Helicoils Screw Thread Inserts | Emhart.com

Andy

 

[Diamondpilot]

I did the same thing to one of my bolts on my Jinma. What I did was get the "about" same size sae stud. I then cleaned out the holes with brake parts cleaner and filled them with JB Weld then put the studs in. The JB Weld acted like a bonding agent and its held better then new. Just let it dry over night. The good thing about this type of fix is you do no take away any meat and if needed later you can drill and retap.

Chris

 

[SPYDERLK]

See if the bolts used the full hole depth. If not, buy a high speed steel plug tap of original size, and tap carefully all the way to the bottom in stages, cleaning chips alternately. Buy new bolts that use all the threads and use Loctite Thread Repair Compound in the holes. If you can get at least two more threads engaged in good metal and then combine with the loctite compound you will be able to put a reasonable torque on the bolts. The loctite will give some thread strength, but the major benefit is that it will make the hole very snug on the bolt and prevent any wiggle or turning. This will make the bolts stay torqued. The loctite is applied so as to not bond to the bolt so they will be able to be removed and reassembled when needed.
larry

 

[RickB]

Keenserts are better than Heli-coils by a wide margin.

Key lock threaded inserts - Keensert - CAMLOC - Insert

 

[Scooby074]

Keenserts are better than Heli-coils by a wide margin.

Key lock threaded inserts - Keensert - CAMLOC - Insert[/QUOTE

I agree., Timeserts are good too. ++ TIME-SERT Metric Kits ++ thread repair kits and inserts repair stripped threads damaged threads repaired threads threaded inserts for metal thread inserts for metal aluminum inserts threaded inserts for aluminum

If it was me, id probably drill and tap to the next standard or metric size, if possible.

 

[Soundguy]

I think I'd drill and tap larger as a first choice, use a thread insert as a next choice, and lastly.. if you wanted to get expensive.. drill and tap for a piece of larger allthread.. install it with a retainer fluid.. then drill that and tap for oem.. seen block repairs like that done.. worked great.. but a bit time consuming..

soundguy

 

[EddieWalker]

From the look of the bolts, I would first try to work with what you have.

Figure out what the thread size is and buy a flat bottom tap to clean out the existing threads. They may or may not be any good, but I bet there is enough metal there that a tap will give you enough to hold onto.

Buy new, American Made bolts in Grade 8 of the same length. If this is something that you don't expect to take off again, use red Loctite. If you think you'll have to remove the bolts in the future, use blue Loctite.

If this fails you, then you can work your way up to the next stage.

Eddie

 

[tugboat-2]

Excellent advice and suggestions from everyone thus far. So it is with the greatest respect to those more experienced than I that I add my own humble opinion here, and as I have said before, I have the greatest respect for Chinese "people",...but absolutely NONE for poor quality junk painted up pretty and sold to unsuspecting folk who are getting ripped off!!! Makes me very angry!!

That said,..... IMHO,...drilling out and retapping and using good, hard American bolts or cap screws etc, (of excellent quality) and tightening them down good and solid to proper torque,.....is a complete waste of time, effort and money!!

You are, in effect, screwing a good quality bolt down into "plastic" or in fact, an inferior quality metal, (likely) made from melted down American rusty scrap cars and other rusted out scrap metal that China buys from us. Just examine the crap that pulled out, threads and all!!!....disgracefull!!!!

You may be lucky to get the bolts snugged down tight, let alone torqued properly before they twist right on out again,...or at least work loose in time.

BUT wait, hold on friend, don't despair,...all is not lost! Once again, IMHO, I would seek the advice of those recommending the use of the Heli-coyle or Keensert "type" remedies that will bury a much better quality "thread" into the soft metal and give you a much better, firmer, more solid "base-thread" than what was there in the original bolt or cap screw hole.

Done properly "this" time, those new, harder bolt threads will get a purchase of greater strength than the original and chances are very good that they will hold their torque for many years of hard service.

I think your wasting your time doing anything less. But, "JUST" MHO !!!
Best of luck to you.

CHEERS!
. . tug

 

[Arkaybee]

Captinjack, just my ojpinion and observation here but to my eye those threads look like they are the wrong diameter or wrong thread size and the male threads appear to be rounded over at their crests. Did you buy this tractor new or used? If it was used could it be that the previous owner replaced these bolts with SAE bolts into metric threads. It is not impossible for the original bolts in a new machine to have had the wrong size metric thread inserted. I have seen this before and the result looks like your bolt threads. I learned the hard way that metric threads are measured very differently from SAE threads. "Metric threads use the same thread profile as SAE threads. The biggest difference is that the thread pitch (distance between consecutive threads) is given instead of threads per unit distance." Here is a good straight-talk description of the differences in bolt threads, etc. Notes on Nuts and Bolts

Maybe this is worth considering--your call.

ARKAYBEE

 

[Soundguy]

thanks for the link.. that's a good read!

soundguy

 

[mcd176]

Heli-Coil is the only way to go in my opinion, I just dont trust the epoxy thread repair systems, I am sure they work but I have used heli-coil for years and have never had one fail. Just my .02

 

[Soundguy]

I've never had good results with epoxy system where you needed good clamping force.

I've made a few things that were aluminum and had composite areas for threading.. but they were simple assemblies with no real clamping power or torque needed.

epoxy threads on a metal part of a tractor??? imho.. not worthwhile..

soundguy

 

[TomOfTarsus]

I'm a little slow here... are the bolts in question at the corners of the cover in the first photograph? If so, I'm wondering how could they get any upward force from the implements? In other words, do we really know the reason for the failure?

Also, don't reach for Grade 8 bolts, they're probably nth degree overkill, esp.if this is indeed just a cover. But I need more details...

 

[Soundguy]

most bolts on ford tractors of era's past were gr5, except in special areas like ring gear replacement bolt sets, and some head sets.. even chassie and cover bolts..

soundguy

 

[Captinjack]

Thanks for all the good information. WOW this is a great site!

Yes. The failed bolts are the corner bolts and yes I bought the tractor new and yes.....I too have had about enough of the poor quality Chinese crap. I don't use the tractor that much and have not abused it and thought I could get away with less than Commercial quality US expensive tractors.

I did a quick measurement of the bolt and I'm confused as to whether it is metric or SAE. I'm going to make an accurate drawing and post a reply tomorrow.

The bolt is listed as a M10X120, but measures 10.8 mm or 7/16 inch in diameter and the treads are larger than that at 11.4mm or 0.45 inch. I haven't measured the thread pitch and will have it tonight for posting tomorrow. The length isn't close to 120 mm as it is about 105 mm which makes me suspect that my parts manual is FOS. This is just great, can't use the tractor because of two nickel ninety eight bolts.

 

[SPYDERLK]

Thanks for all the good information. WOW this is a great site!

Yes. The failed bolts are the corner bolts and yes I bought the tractor new and yes.....I too have had about enough of the poor quality Chinese crap. I don't use the tractor that much and have not abused it and thought I could get away with less than Commercial quality US expensive tractors.

I did a quick measurement of the bolt and I'm confused as to whether it is metric or SAE. I'm going to make an accurate drawing and post a reply tomorrow.

The bolt is listed as a M10X120, but measures 10.8 mm or 7/16 inch in diameter and the treads are larger than that at 11.4mm or 0.45 inch. I haven't measured the thread pitch and will have it tonight for posting tomorrow. The length isn't close to 120 mm as it is about 105 mm which makes me suspect that my parts manual is FOS. This is just great, can't use the tractor because of two nickel ninety eight bolts.

Take out one of the "good" bolts next to them. Measure to the very bottom of the hole and compare to bolt length. You may have some significant extra hole depth that is already threaded or that you can thread and use as a safety margin on all the bolts. If you have this, and use all the extra thread depth available the Loctite thread repair kit will do the job on those outer bolts as well since [by description] they are not highly loaded. If you ever have to repair a threaded hole with real metal your best bet by far is to go to a larger dia bolt or use the case sert type of insert recommended highly above. Heli coils are ok, but not in the same league.
larry