Need help with metric bolts sizes and grades

[kco]

I've searched TBN and the internet and am unable to determine what the markings mean on bolts on my Kioti DK35.

Bolts holding in loader pivot pins in place are 10 mm in diameter and have:

DD
7T i.e. "DD" over "7T"

Large bolts mounting the loader to the frame are 14 mm diameter and have the marking:

OM
10.9 i.e. "OM" over "10.9" over and underline

The smaller loader mounting bolts are 12 mm in diameter and have the marking:

DS
9 i.e. "DS" over "9"


Large bolts mounting the ROPS base to the frame (diam. unknown (approx 20 mm?)):

7T
DS i.e. "7T" over "DS"

The large main bolt that the foldable ROPS swivels on (diam. unknown (approx. 25 mm?)):

10.9
DH i.e. "10.9" over underline over "DH"

Does anyone know what these markings mean? I'm confused because the torque chart that came with the loader just lists torques for ISO Classes 8.8, 10.7 and 12.9.

 

[BillP603]

I know the 10.9 is a grade marking, like Grade 5 Grade 8 is for standard bolts. The double letter is a manufactures mark required by the DIN standards. Not sure on the T, I believe it may mean tempered. Here are a couple of links to technical information that I have used in the past:

Technical Information | Fuller Metric Parts Ltd.

Frequently Asked Questions on Bolting Matters

Hardware is one of those things that there "are so many standards to choose from"...

 

[grsthegreat]

i was in the same quandry..... the torque guide lists the bolt thickness also as i remember. i used the thickness of the bolt to determine the torque

 

[kco]

I did a bit more digging and found bolt standards to be quite confusing.

The markings such as 7T (other common ones are 4T and 9T) are Japanese Industrial Standard (JIS) grades and indicate 1/10 of the nominal tensile strength in kgf/mm2.

Metric grades such as 8.8 indicates a nominal (minimum) tensile ultimate strength of 800 MPa and nominal (minimum) yield strength of .8 times tensile ultimate strength or 0.8(800) = 640 MPa.

A metric 10.9 bolt is medium carbon steel, quenched and tempered while a 10.9 (underlined 10.9) is a low carbon boron steel, quenched and tempered.

What is very confusing with my Kioti DK35 is they use a different bolts for the loader mount. The front four main bolts are 14mm diameter, DIN 10.9 bolts that have a 22 mm head and are torqued at 164 lbf-ft. The back four main bolts are 14mm diameter, JIS, 9T bolts with a 19mm head and should be torqued at 133 lbf-ft.

If the front four bolts where ANSI/ISO instead of DIN they all would be the same except the head would be 21 mm instead of DIN's 22 mm.

I torqued the JIS bolts incorrectly because I assumed all bolts were the same type (DIN) and that the Kioti loader parts diagram had the wrong diameters. The four front bolts had 22mm heads and the four back ones 19mm heads. So (incorrectly sticking with the DIN type) I assumed the back ones were 12mm diameter. I now think they are 14mm diameter bolts (with the JIS 19mm head) as labelled in the parts list.

I've attached a Metric Bolt Head/Wrench Size table.

 

[grsthegreat]

I did a bit more digging and found bolt standards to be quite confusing.

The markings such as 7T (other common ones are 4T and 9T) are Japanese Industrial Standard (JIS) grades and indicate 1/10 of the nominal tensile strength in kgf/mm2.

Metric grades such as 8.8 indicates a nominal (minimum) tensile ultimate strength of 800 MPa and nominal (minimum) yield strength of .8 times tensile ultimate strength or 0.8(800) = 640 MPa.

A metric 10.9 bolt is medium carbon steel, quenched and tempered while a 10.9 (underlined 10.9) is a low carbon boron steel, quenched and tempered.

What is very confusing with my Kioti DK35 is they use a different bolts for the loader mount. The front four main bolts are 14mm diameter, DIN 10.9 bolts that have a 22 mm head and are torqued at 164 lbf-ft. The back four main bolts are 14mm diameter, JIS, 9T bolts with a 19mm head and should be torqued at 133 lbf-ft.

If the front four bolts where ANSI/ISO instead of DIN they all would be the same except the head would be 21 mm instead of DIN's 22 mm.

I torqued the JIS bolts incorrectly because I assumed all bolts were the same type (DIN) and that the Kioti loader parts diagram had the wrong diameters. The four front bolts had 22mm heads and the four back ones 19mm heads. So (incorrectly sticking with the DIN type) I assumed the back ones were 12mm diameter. I now think they are 14mm diameter bolts (with the JIS 19mm head) as labelled in the parts list.

I've attached a Metric Bolt Head/Wrench Size table.

I just went to check my dk45, and all 9 loader mount bolts are the same. Its a new tractor, so i guess they changed some stuff.

 

[SixHoeBob]

I have yet to find any torque settings on my Vise-Grips. For lack of a better system,I try to tighten all bolts to 1/4 turn before breaking.

 

[kco]

I just went to check my dk45, and all 9 loader mount bolts are the same. Its a new tractor, so i guess they changed some stuff.

The KL401 loader found on the DK40/45/50's is a bit different than the DK35's KL351. The main front 4 KL351 M14 bolts are longer than those used on the KL401. Perhaps the longer bolts are not available as JIS so they use ISO bolts.

I was in town last night and checked a DK50 on the dealer's lot and saw all the bolts are the same type JIS as you mention. I should have trusted the Kioti Loader manual parts list instead of incorrectly assuming bolt diameters from the head sizes. But I don't have a lot of faith in the manuals.

Strangely, the manual's torque table shows torques for only ISO type bolts that don't exist on the KL401 and are only the two sets of the front four bolts on the KL351. Even in this table they label the bolt as 10.7 instead of the correct 10.9.

Anyhow, my confusion is cleared up now.

 

[grsthegreat]

The KL401 loader found on the DK40/45/50's is a bit different than the DK35's KL351. The main front 4 KL351 M14 bolts are longer than those used on the KL401. Perhaps the longer bolts are not available as JIS so they use ISO bolts.

I was in town last night and checked a DK50 on the dealer's lot and saw all the bolts are the same type JIS as you mention. I should have trusted the Kioti Loader manual parts list instead of incorrectly assuming bolt diameters from the head sizes. But I don't have a lot of faith in the manuals.

Strangely, the manual's torque table shows torques for only ISO type bolts that don't exist on the KL401 and are only the two sets of the front four bolts on the KL351. Even in this table they label the bolt as 10.7 instead of the correct 10.9.

Anyhow, my confusion is cleared up now.

good point. i think i will try and get a proper torque table from Fasteners inc.... just to be sure. by the way....does anyone here use torque sticks here....the things you can place on the end of a impact wrench to set torques??

 

[Transit]

I would never use torque sticks, use a 6 point socket and a half inch drive click type torque wrench. For smaller bolts use a 3/8 inch drive wrench, I also like to use ant seize compound and set the torque to the lower value in the range.

 

[kco]

good point. i think i will try and get a proper torque table from Fasteners inc.... just to be sure. by the way....does anyone here use torque sticks here....the things you can place on the end of a impact wrench to set torques??

I've attached the torque table my dealer sent me for the the JIS 7T and 9T bolts.