chassis repair

[Longmeadow farm]

Re: New Holland T4.75 with 4wd and loader.....frame twisting is loosening chassis bolts...

Has anyone had experience repairing/fixing transmission/rear end case threads using a thread repair approach such as heli coil or something similar. Tractor twisted the bolts loose after 3 years of service. Changed bolts, cleaned bolt holes, etc... lasts about 9-12 months and loosens up again... leaking fluid et al...,

I believe that the tractor is too light for the loader a 655 TL which is used on NH tractors that are 2000 lbs heavier. I've concluded that,in my application, I need a heavier chassis tractor.

Please keep the commentary directed at the possibility of case/chassis thread repair. Dealer has not been that all that helpful

thanks

 

[Steve@Advance]

There is no easy fix for that.

A couple things happen when bolts work loose.

The threads are damaged, both the threads on the bolts, and the tapped holes. The bolts are easily replaced, the threads can be repaired with recoils or thread inserts. When installing recoils or inserts, it is critical to put the part in a mill, use a mag base drill, or use a drill guide if hand drilling. The hole must be kept straight for any hope of success.

But the difficult part is, the mating surfaces are no longer going to sit flat and secure to each other. The machined surface is now distorted. The only solution is to somehow restore a machined flat surface to both surfaces. It will require machining down to clean up, or welding the surface back, then machining it down to the original specs. Not an easy job. Trying to do so with a grinder or file... Well, it might look better, but unless you are extremely good, or get real lucky, it just won't be right.

Looking back to the original cause...

As you suspect, the loader may have been too big to begin with. If that is the case, nothing can be expected to hold up short of properly restoring the threads and the mating surfaces, then reinforcing what you have to work with by adding extra bolts, dowel pins, extra brackets, hard to say with out seeing it.

Or the original bolts may have been the wrong grade, were not properly torqued, or the components were assembled with heavy paint between the surfaces. That's why the dealer is not being helpful, they don't want to admit any wrong doing, and they know there is no easy fix.

 

[MSM]

Use a C-sert. Instead of a helicoil.
They are solid and won't strip out. I
have used them on stripped frame bolt
holes on numerous Deeres. Never had a
failure.
On your tractor, until it can be
repaired properly, I would go over
the frame bolts every 10 hours. The
frame bolts don't loosen all at one
time, one or two come loose, then the
extra movement loosens the others. If
your loader is too big for your
tractor then I would look for the
proper sized loader or get a larger
tractor. This is assuming you are usi
ng it within your tractors capacity
capacity and not as a bulldozer or
trying to pick more than it should
and traveling over rough terrain

 

[gab]

About twenty years ago my boss bought a New Holland new with a big loader, don't remember the numbers but it had a turboed 4 cyl., Nice tractor, anyway I crawled under it to change the oil and noticed the front of the oil pan had bosses where the front 4x4 axle was bolted and they were busted out of the pan. Then noticed the whole front axle was loose, so he traded it off for a bigger tractor. He was trying to pull a big dirt scraper with the first tractor.

 

[SVcummins]

Have you tried green loctite

 

[showcrop]

As you request I will keep my commentary directed at the possibility of case/chassis thread repair.........................................................................................................

.

 

[Longmeadow farm]

I would like to thank all those who responded in a positive fashion. I learned stuff I didn't know and now have additional options. I contacted another NH dealer and they seem interested in discovering why the tractor chassis loosened up...asking a number of operational use questions. I may have caused the problem .. but fixing the tractor without knowing what i need to do to alter my behavior is rather stupid in my estimation. Anyway thanks again..