So I went to my CAT dealer today and picked up some bolts for my never ending D6 project grouser.

My D6 has BERCO tracks and several of the shoes are loose. My plan is remove the loose shoes, clean up, and reinstall with new nuts and bolts. In my CAT part book the bolt is # 2F1009 which changes over to 7H-3596.

I ordered 40 to get me started, they had about 10 in stock. I get home and see they no big enough ( as Oilslick would say). So, go back to CAT and get the correct size (5/8") .... I guess.....

I asked for lock washers, as listed in the parts book, but the parts guy said he had never seen those used on track shoe bolts - ever. My D2 3J has lock washers, my TD 15 does not. My BERCO tracks has some lock washers, some ny-lock nuts and some of both.

Washers or no lock washers ?

Picture is BERCO bolt vs CAT bolt -thanks

i did lot of undercarriage at the dealer in the early 2000's, we made sure there was no paint between grouser and rails, and no paint where nut contacts the rail. no washers, just bolts and nuts.

Since the 1970's (at least) lock washers have not been used. The square nuts 1M-1408 have beveled edges to seat and be self locking in the rails. 7H-3597 are the recommended 5/8" bolts.
Current installation recommendations is lubricated bolt threads and bolt washer faces, tighten to 120 +/- 30 ft. lbs. plus and additional 1/3 turn. Suggests re-tightening after 50-100 hours of operation.

If your tracks are not spot faced for square nuts I'd say the lock washers (heavy duty hardened) are optional. Problem with lock washers is they have been known to break under conditions that frequently cycle the bolt loading.

Where I look online the 7h 3596 is a 9\16 bolt. My tracks have 5\8.

I guess if I take my BERCO bolt to the cat dealer and can match the shank design with a cat part I'm ok.

I will take a look at the underside of the tracks, but I can only guess what is supposed to be there based on what's there now ( lock nuts with lock washers Etc ) I'll try to get a picture to share

Thanks

I don't wish to depress you, however track shoe bolts are shouldered and a neat fit in both the shoe and track link. If the shoes have come loose, generally the holes have wallowed and bolts are no longer firm fit, when this happens you may find that the shoes can never be kept tight. I have experienced this myself, eventually resorting to welding the shoes to the rails, in one case on D8L tracks, discarded them before they were totally worn out. Did have some success with welding on D6D tracks.

Wombat

Hi, Tognot.
IMHO. both Old Magnet and Wombat - "the mad mouth from the South" - are right, OM about the no washers and the tension and Wombat about the bolts being a neat fit in the holes to help hold the plates in place without movement to create wear and thus loosen the bolts. I personally have not seen washers of any kind on track plate bolts since the 1960's. Just make sure there is NO paint left on any of the mating surfaces, plates. rails or bolts.

For the same reason, don't leave any paint on a new wheel or hub when installing.

Just my 0.02.

Ok thanks guys.

There is a BERCO dealer within 75 miles of me. I'll call and see if they have any idea what tracks I have.

If no success there, I'll go back to cat with my BERCO bolt and try to match it up and get some nuts designed to be used without washers.

Just thinking.. Let's say the BERCO chains are not ground / designed for no washer. Wouldn't a flat, ground washer be better than a lock washer ? Seem less chance of flexing/ coming loose.

Wombat, I understand your point. The chains seem pretty tight where the bolts go through. All I can do is try. Maybe plan on the torque procedure described by old magnet and use red loctite as my bolt lubricant ?

Thanks all

Sorry, snagged your 7H-3596 bolt number. The 5/8 bolt is a 7H-3957.
A hardened regular washer would serve no purpose when using the proper high head height hardened nuts of the type that was used with lock washers.

Check your rails, D6's started out with 7H3596 bolts and 7K2017 nuts. The change to 5/8 uses the square nuts. This applies to Cat tracks, not sure if Berco would be any different.

The change to 5/8 bolting occurred at s/n 9U27945 (1958)

I don't remember seeing any tracks with lock washers produced after the late '50's, the change to square nuts only, occurred about the same time as the change to 5/8" bolts on D6 size track. Berco will have copied Cat.

Been some time since I purchased any of the hardware. Berco us to have both the 9/16 and 5/8 bolts and square nuts. Last I knew Cat did not have the domed head 9/16 bolts in the right length, the nuts are available as that was used on D3.


The one D6 here lived in your flat land, at Fresno. Almost new Cat rails old very worn grousers installed with lock washers. More loose grousers than tight ones all before I ran it several 100 hours around rocks. So in this case they broke under very mild shock loading.None of the bolts lose nuts and fall off, just rattle and wallow the wholes out bigger.