Description

BISO 6170, 7070, 7071 Parts Catalog – What You Get on the Bench

If you have a BISO straw chopper on a combine or a stationary unit, you already know the frustration. You pull a knife assembly, find a worn bearing on the flail drum, and then spend an hour flipping through aftermarket websites trying to match a blurry photo. This BISO 6170, 7070, 7071 Parts Catalog is the 96-page OEM document that kills that guesswork. I’ve been torqueing bolts since before most of you were born, and I can tell you: factory parts catalogs are the only thing I trust when a customer brings in a machine that’s been cobbled together with mismatched hardware. Aftermarket catalogs renumber parts, leave out supercessions, and sometimes show the wrong side of an assembly. Not here.

Page 1 of this catalog lists every section under “TOOLS AND ACCESSORIES – CHOPPER.” You get the exact reference numbers – KNIVES (4U.36.1), V-BELT (4U.36.2), BISO-STRAW CHOPPER BASIS FRAME (4U.36.51), FLAIL DRUM WITH BEARING (4U.36.52), and all the way through the chaff spreaders and conversion kits. Each assembly gets its own exploded diagram with the part number stamped next to every nut, bolt, and belt. You don’t guess. You read the number, order the piece, and move on.

Knife and V-Belt Sections: Why OEM Part Numbers Matter

The KNIVES section (4U.36.1) lists every blade variant BISO produced for the 6170, 7070, and 7071 models. Aftermarket blades often have a different hole pattern or thickness – I have seen a field fix fail because a generic knife sheared off its mounting pin at 2,000 rpm. The V-BELT section (4U.36.2) gives you the factory belt length and cross-section. You need the right belt to maintain the correct tension on the flail drum; too loose and you lose chopping efficiency, too tight and you burn out the layshaft bearing. This catalog saves you a second trip to the supply house.

Basis Frame and Flail Drum Assembly: 4U.36.51 and 4U.36.52

These two sections cover the core structure of the chopped. The BISO-STRAW CHOPPER BASIS FRAME (4U.36.51) shows the main weldment and all attachment points. The FLAIL DRUM WITH BEARING (4U.36.52) is where most wear happens. A bad bearing will ruin the drum housing if you let it go. The catalog gives you the bearing part number and the fastener torque specs printed right next to the illustration. You want to replace that bearing without pulling the whole drum? The diagram shows you the exact sequence of snap rings and spacers. That’s the difference between a two-hour job and a six-hour nightmare.

Electric and Mechanical Clutch Options for 7070 and 7071

BISO offered two clutch systems on the 7070: an electromagnetic clutch (EL.MAGNET CLUTCH “W”-VERSION – 4U.36.65) and a “S”-version (4U.36.66). The 7071 uses a vee belt clutch (4U.36.67). If you own a 7070 and need parts for the electric clutch, the catalog lists the coil, armature, and wiring harness separately. Page 1 shows the section headings, but the detailed diagrams start on the individual sheets. You will not confuse the two versions because the exploded view for 4U.36.65 shows the wiring pins; 4U.36.66 omits them. That kind of distinction is impossible in a generic parts list.

Conversion Kits: When Your Chopper Has a Different Clutch

BISO produced conversion kits (4U.36.70, 4U.36.71, 4U.36.72) to swap between vee belt and electromagnetic clutches on the BISO-STRAW CHOPPER. The catalog includes the complete hardware list – bolts, brackets, belt tensioners. If you are retrofitting a 7070 to the 7071-style vee belt drive, you need those three pages. I have seen shops order the wrong conversion kit because they guessed the serial number cut-off. This manual shows you the exact frame serial ranges (like +Y 05542 -Y 06439) so you know which bracket pattern matches your machine.

Chaff Spreader Variants: Know Your Machine Serial Number

Chaff spreaders are often ignored until they clog. The catalog dedicates multiple sections to the BISO-STRAW CHOPPER CHAFF SPREADER W (4U.36.73 through 4U.36.76) and the KPAB-STRAW CHOPPER variants (4U.36.77 onward). Some spreaders are for the 6170 only; others fit all three models. The part numbers differ by a single digit – order the wrong one and the mounting holes won’t line up. The catalog uses serial number prefixes (-Y 05147, +Y 05148) to differentiate. You don’t guess. You read your machine’s plate and pick the right section.

Why This Catalog Beats Aftermarket Copies

I have seen reprints that combine multiple brands into one PDF, leaving out the BISO-specific notes about layshaft support differences between the 7070 and 7071. The layshaft support for 7070 is 4U.36.61; for 7071 it is 4U.36.62 – they look identical in a photo but the bolt pattern is shifted 10 mm. An aftermarket copy might show one image for both. This factory catalog keeps them separate. The document is a scanned original, so you get the original BISO part numbers, not renumbered aftermarket stock codes. If you want to cross-reference, check Automotive Industry Overview for general background on agricultural equipment standards, but for your BISO parts, stick to the factory source.

Related manuals you might need: BISO Straw Chopper Parts Catalog for additional model years, BISO Straw Chopper 6170 7070 Parts Catalog for a combined reference, and Massey-Harris-Ferguson FF 30 GS 1957 Parts Catalog | OEM Fastener Guide for older combine fastener specs. Automotive Industry Overview also provides context on torque standardization, but that’s background.

FAQ – Common Questions About This Parts Catalog

Does this catalog include torque specifications for the fasteners?

Yes, the exploded diagrams list the tightening torques next to each bolt or nut where BISO specified them. For example, the flail drum bearing housing bolts are called out with a torque value in ft-lbs.

Can I use this for the 6170 model alone?

Yes.

Are the conversion kits (4U.36.70–72) still available from BISO, or do I use the part numbers for ordering aftermarket equivalents?

BISO may have discontinued some kits. The catalog provides the original part numbers, which you can take to any dealer. If the kit is NLA, the exploded view shows every component, so you can source the individual parts (bracket, bolts, spring, etc.) yourself. Do not substitute a generic vee belt clutch assembly expecting the mounting holes to match – the frame cutouts are specific to each serial range. Check the “+Y 05542” notes on page 2 of the applicable section before ordering.

How many pages does the catalog contain?

96 pages covering every section from knives to chaff spreaders, plus conversion kits.

Stop wasting time paging through generic parts sites. If you own a BISO 6170, 7070, or 7071 straw chopper, this is the only parts list that matches your machine. Access the Factory Manual now and keep it on your workbench.