666 opinions

SATom · Mar 3, 2009

I was wondering if you could give me an opinion of the Farmall 666 tractors. There is one for sale locally, has around 4500 hours, diesel, new paint, dual remotes and runs excellent. The price is $7500. Is this series a good tractor for general farm work? I would need to find a loader for it, and will be used to spread manure, make wrapped round bales, and possibly be used on a feed wagon. What are some things to look for on these tractors and is the price good? Thank you.

Tom

kdstene · Mar 3, 2009

a 666 is a glorified m. take that 7500 and buy a decent 1066. way more dependable and cheaper to work on.

Allan in NE · Mar 3, 2009

Tom,

Just buy the thing before someone else does.

Worth every penny and IH didn't EVER build a bad one.

Allan

TractormanNC · Mar 3, 2009

If you need a 60-65 hp tractor, the 666 is one of the best. If it is in good condition and they are scarce as hen's teeth like around here, the price is about right, some people will say its waaay too much.

Good hydraulics, good 3pt, good P/S. Be sure to check the T/A if it has one. That D312 is the little brother to the IH 400 series engines which are well known for reliability.

460/560 · Mar 3, 2009

Make that a very HIGHLY glorified M. I restored a 656 few years ago, which isn"t as nice as a 666, and it would work circles around a M. It is a very smooth, comfortable tractor. 666 would be much better than M for loader work and heavy pto work. 7500 is a little on the high side, but this is a very handy tractor.

Hugh MacKay · Mar 3, 2009

kdstene: I'll bet there are a lot more poor condition 1066s out there today than 666s. Further, the 1066s could gobble up 5 times the dollars to come up with a decent one.

erik dekeyser · Mar 3, 2009

I agree with Hugh the 666 and the 686 are one of the best tractors IH ever built.They are not to big and not to small,with the 6 cylinder they are a very smooth running tractor.

Hugh MacKay · Mar 3, 2009

Erik: Yes sir, if I were to return to farming a 656, 666 or 686 gear drive diesel would be a must. If I needed a 100+ horsepower, it would have 8 - 20.8x42 tires and hinged in the middle. Forget this 100+ horsepower two wheel drive junk.

Since I don't intend to do that, it won't matter.

Nebraska Cowman · Mar 3, 2009

Like Allan says, Buy it now. There ain't much wrong with a 666.

georgeky · Mar 3, 2009

The 666 is a lot more than a glorified M. It is one of if not the best tractor IH ever built. That American 312 engine will rock and not to hard on fuel, start fairly well in cold weather, and just plum handy. They don't cost anymore to work on than any other. I have a 1974 version of it and it is still a damn fine tractor. Very dependable tractor and always ready to work. Mine will pull a 4 bottom plow anywhere you put it. Tractor pullers dream about 666/686's with the American 312 engine in them.

7500 seems high to me but see what 7500 will get you towards a new tractor that will do what the 666 will.

Hugh MacKay · Mar 4, 2009

George: Well put, no one can describe the 666 much better. 656 with 282 was a great tractor, the 312 engine in 666 made it even better. Then IH decided to nickel and dime the tractor by using the 310 engine in the 686.

I don't think the 66 series front end with external steering cylinder was an improvement over 56 series steering. My 1066 steering was far more troublesome than 656. I may be a bit prejudiced as I suspect the duals on my 1066 had a lot to do with front end problems. I have a close friend bought a new 666D, he found much the same front end problems, however not to the extent I did on 1066. None of these tractors ever had a loader, other than my 656 may have seen 100 hours of loader work when new.

I had an articulated Deere, and in my opinion if your going over 100 hp, you want big wheels and tires up front. An articulation point is far less expensive to maintain than steerable front drive. My 1066 was a great PTO tractor and a great drawbar tractor with 20.8x38 duals but OH my gosh the cost of that front end was an excessive expence to keep running. Even though I thought the 1066 a great drawbar tractor it didn't hold a candle to the articulated Deere, which actually had less hp.

No question, probably the 666 was IH finest hour.

mkirsch · Mar 4, 2009

Little-known factoid, but the 666 is actually based on the *H*!!!

If it's a glorified anything, it's a glorified H.

Hugh MacKay · Mar 4, 2009

MKirsch: Bullfeathers, there absolutely nothing about that tractor "H" related. Same size axles and wheels as an M. Heavier bull gears, differential and transmission than an M. 11" clutch same as 450, 560 and 656. H only had a 10" clutch.

mkirsch · Mar 4, 2009

Hugh, I won't argue that the internals have been upgraded from an H. My Super H has a 10.5" clutch, and there's plenty of room in there for an 11".

I never believed it myself until I saw a 460, 560, and 656 sitting together at a tractor show. The 656 has the same frame rail bump-outs at the bell housing as the 460. It all measures up. The 656/666/686 tractors have the same narrow bell housing bolt pattern as an H.

H -> Super H -> 300 -> 350 -> 460 -> 656 -> 666 -> 686.

Am I saying that the 666 has H parts? It shares very little in common, I'm sure. What I am saying is that it's true lineage can be traced back to the H at the bell housing.

The M sized housing ended at the 560.

Hugh MacKay · Mar 4, 2009

Kirsch: Since the 300, 350 and 460 only had a 10" clutch, could you explain why a SH needs a 10.5" clutch. M, SM, SMTA, 400, 450, 560, 656, 666 and 686 all had an 11" clutch.

Truth is during the 1950 there was great advance in casting, gears and clutch technology, those items didn't need size increase to add six cylinder engines up front.

Look ahead to 1975, 140 had a 9" clutch, everything from 140 on up to 70 hp had an 11" clutch, 766 and 966 only had a 12" clutch, 1066, 1466 and 1566 were all 14" clutch.

I've had the transmission top off my 130, H, 300, 560 and 656. I can tell you all gears in H and 300 are a lot closer in size to 130 than 560 or 656 and 656 is heavier than 560.

Time for reasoning, rather than your nonsence.

mkirsch · Mar 4, 2009

Nonsense? Nonsense!

But, I'm never going to convince the "Mighty Hugh McKay who is always right(tm)." Even if I took an H front end and bolted it to a 666 rear end.

I learned long ago not to argue with stubborn old farmers for very long. It just gets you dirty and angers the stubborn old farmer.

Maybe I'm a little out of line here but Hugh you are WAY out of line. I've done the research. I've taken the measurements. I've had the tractors sitting side by side. Give me a little credit here.

georgeky · Mar 4, 2009

There is nothing on a 666 that remotely resembles an H except maybe a tricycle front end. That is pure BS/hog wash/jibberish or whatever you want to call it. I have never seen an H that will pull a 4 bottom plow or my big NH grinder/mixer. I have never seen an H with a 17 GPM hydraulic pump, I have never seen an H with factory PS, and factory 3 point hitch with dual or even triple live remotes

Yes I have an H, I also have 2 M's and a couple C's and SC's, a 450, and 350. The 666 will eat any of them in the field.

georgeky · Mar 4, 2009

Hugh, my 666 is a tricycle and has no external cylinder I am aware of. In any event I have never had a bit of trouble out of my steering. So far anyhow.

The first day I used my 666 when I got it I had it hooked to my 15 foot batwing bush hog. I decided that day that I was born to ride a 666. I remember dad bought a new 584 in 1980 and there was a new 686 sitting right beside it. I tried my best to get him to buy it instead of the 584. He thought it was to big for what he needed. Until I got my 666 I always wondered what it would be like. Once I started running it I wished I had bought the new 686 even though it may have had that German D310 in it. I stand by my earlier statement that 666 is one of the very best tractors ever made by anyone.

Hugh MacKay · Mar 4, 2009

George: Your 666 narrow front would require same front bolster as 656 with internal steering cylinder. About the only way to accomodate a narrow front. My friends 666 wide front used the external steering cylinder behind the axle, same as on my 1066, and other larger 66 series tractors.

Can't argue with your statment, I always said, only thing to improve a 656 was get rid of the glow plugs.

Allan in NE · Mar 4, 2009

Your friend's 666 has been "cobbled".

Small frame tractors NEVER used the external cylinder. Ever. Neither the 666 or 686.

Allan

Hugh MacKay · Mar 4, 2009

Allan: Sorry, but I saw that 666 the day it was delivered new, and the external cylinder was on it.

georgeky · Mar 4, 2009

Hugh, I dragged out my IH service manual for 544, 656, 666, 686 and the hydro models. It only shows an external cylinder for early 544 and 656 tractors. Shows none for late 656 right through to the 666, 686, hydro 70 and hydro 86. Everything my book shows for those models are just like Allans picture.

mkirsch · Mar 4, 2009

georgeky, I never said a 666 *was* an H, I said it was BASED on an H.

Sit a 666 and a 460 side by side. Same frame rails. Same torque tube. Nobody argues that the 460 is based on the H.

This is my last comment on this. Believe what you want to believe. I know when I'm beat.

Hugh MacKay · Mar 4, 2009

George: I really never looked into this and must admit I never paid much attention to any 666s other than my friends 666, I assumed they were all external cylinder. His was one of the last 666s bought in 1975-76. Can't give you an exact date, but it was after I bought my 1066 in Sept of 75.

I know at the time I thought of trading my 560 and upgrading to a 666. I could see this small chassis Farmall was about to be phased out in favor of those German built 74 and 84 series.

Hugh MacKay · Mar 4, 2009

Kirsch: You could fooled me, I thought you said, "666 was derived from an H."

Steven f/AZ · Mar 4, 2009

(quoted from post at 16:54:17 03/04/09) georgeky, I never said a 666 *was* an H, I said it was BASED on an H.

Sit a 666 and a 460 side by side. Same frame rails. Same torque tube. Nobody argues that the 460 is based on the H.

This is my last comment on this. Believe what you want to believe. I know when I'm beat.

Just because the width of the frame rails and torque tube measures the same, means it's BASED on an H? Gee, if my car's bellhousing is the same width as my H, was my car based on a Farmall H?

Back to original question - I would say the 666 was one of THE BEST tracctors IH ever built. Nice size, easy to manuever, efficient, reliable, bulletproof. Just near perfect in my book.

Hugh - Dad's 1086 has been run with duals and about 1000 pounds of suitcase weights up front since new and is nearing 10,000 hours. The front end center bushing and pin were replaced/rebuilt around 8000 hours. Spindles have never been off of it, probably put several tie-rod ends on each side (outboard only, the insides maybe replaced once each). We have always run the 4-rib tires, if that makes any difference. What are your issues with the 1066 front end? Just asking for future reference...

Hugh MacKay · Mar 4, 2009

Steven: My issue, my 656 at 15,000 hours, still had all it's original tyrods, spindles, main pivot pin, etc. 1066 a very little heavier front end had been completely rebuilt 3 times in 15,000 hours. 1066 never had a loader, yet it broke two spindles from front wheels bogging down insoft ground. Yes I believe operator could have been a bit more alert, however at 6 mph there was little time.

Lets face it these issues just don't happen with articulated tractors. Sure we can go conventional tractor with front drive and 24" front tires, however I see guys rebuilding those every 5,000 hours, not cheap either. The first and only time I replaced articulation joint on my Deere was at 11,000 hours, pivot only the steering cylinders were fine. As I recall those upper and lower replacements were under $100.

georgeky · Mar 4, 2009

The 460 was not based on an H. The 460 was a comprimise when the 450 beacame the 460 and 560. In other words the 450 was made into two versions. I have read this first hand from IH documents and they made no mention of the H. The H played no role what so ever in the development of the 460, 560, 656, 666 and so on.

Steven f/AZ · Mar 5, 2009

(quoted from post at 19:39:15 03/04/09)Lets face it these issues just don't happen with articulated tractors. Sure we can go conventional tractor with front drive and 24" front tires, however I see guys rebuilding those every 5,000 hours, not cheap either. The first and only time I replaced articulation joint on my Deere was at 11,000 hours, pivot only the steering cylinders were fine. As I recall those upper and lower replacements were under $100.

Thanks for the info. I agree that articulated is the way to go for field work over 100 hp. I wouldn't trade our 4x4 tractor for anything other than another 4x4 in heavy field work.

kdstene · Mar 5, 2009

hugh: never said a 666 was a bad tractor. said it was a glorified m. many others will agree with me here that the 666 evolved from the h/m beginings. sure they made several excellent improvements but was only improvements, not a totally new design.

Hugh MacKay · Mar 5, 2009

kdstene: That is right, IH kept the 656, 666 and 686 relatively simple. Precisely why I'd never advise anyone looking for 65 hp to buy a large chassis tractor. Those large chassis tractor can make a man weep at the parts counter, exactly why they sell so damn cheap.

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