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acplowboy45 
Silver Level
Joined: 09 May 2013
Location: connersville IN
Points: 266
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 Topic: Allis Chalmers 7080
Posted: 08 Apr 2026 at 8:46pm |
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Looking at a 7080 and was hoping someone could tell me if the 7080 had rear end troubles. Also how can one tell if the power director shifter is bad without hooking up gauges. I have read don't run them hard about 2200-2300 rpm is all you need no higher. Is that correct. Appreciate any input.
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DrAllis
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Joined: 12 Sep 2009
Points: 22844
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Posted: 08 Apr 2026 at 9:46pm |
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Not known for rear end problems. I could drive one for 15 minutes without gauges and tell you if the Power Director clutch is good or bad. 2800 RPM is bad. Less is better, correct.
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Lynn Marshall
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Joined: 13 Sep 2009
Location: Dana, Iowa
Points: 2492
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Posted: 19 hours 58 minutes ago at 7:50am |
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I certainly wouldn't fear the rear ends or the power director either. The power director had an extra plate in the low side and maybe another one in the high side? The torque limiter would need to be in top shape. The engine was probably the weak link. If left in stock settings and properly serviced, they should last a long time. Turning them up shortened their life. Question for Doc or Injpump Ed, with a stock pump setting, what kind of horsepower would you see at only 2300 rpm. I would think that 2500 or so would be comfortable for the engine and still have somewhat adequate horsepower.
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DrAllis
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Posted: 18 hours 23 minutes ago at 9:25am |
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It's been many years since I've had one on a dyno, but if I remember right, when you pulled one down below 2550 RPM rated speed, the needle on the dyno just kept coming on around !!! I'll bet it would have still had 160 HP or better @ 2300. Maybe 170......
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8070nc
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Joined: 21 Mar 2019
Location: North Carolina
Points: 728
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Posted: 17 hours 23 minutes ago at 10:25am |
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If you get the tractor id put a new torsional damper on the front of the crank. I could say why i recommend that but it would be a long story
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1984 80780
1957 D14
DES 300 with 25000 engine
616 tractor
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bigal121892
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Joined: 05 Jan 2010
Location: Nebraska
Points: 820
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Posted: 9 hours 19 minutes ago at 6:29pm |
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If it were me, I would put in a new front dampener, plasti-gauge the rod and main bearings, and check the condition of the pinion shafts, and the bolt that holds them together.
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SteveM C/IL
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Joined: 12 Sep 2009
Location: Shelbyville IL
Points: 8997
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Posted: 4 hours 51 minutes ago at 10:57pm |
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The viscous damper is available from aftermarket. Think AGCO says NLA....
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CrestonM
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Joined: 08 Sep 2014
Location: Oklahoma
Points: 8484
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Posted: 4 hours 41 minutes ago at 11:07pm |
http://klmperformance.com/products/detroit-diesel-series-71-crankshaft-damper?variant=21998774386772
This damper has the same measurements as the original. I put one on my 7080, and it took the slight vibration out of the exhaust stack that was there before. I cut the old damper in half to see what the inside was like, and the viscous fluid had turned solid, like cured silicone. I recommend everyone with a 7080/8070/4W-220 replace the damper, especially if you don't know when/if it was replaced before. A lot cheaper and easier than installing a new crankshaft. Be gentle with the new damper when installing it, if you were to drop it and dent it, that will keep the inner ring from "floating" and doing its job, rendering it junk.
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