Author Topic: Head Nuts - Standard or ????? (Read 4921 times)

timbo750 · « **on:** January 28, 2014, 05:22:12 PM »

I know that this has been discussed before but I have not found enough evidence to have a clear answer as to which way to go with this. I understand the need for HD head studs and I understand that HD nuts are beneficial if required but I have not been able to find someone who has experienced failure of the nuts in a street application with either a stock or modified engine.

Anyone got any valuable feedback please?

750cafe · « **Reply #1 on:** January 28, 2014, 07:58:50 PM »

More likely than not, the reason for the HD parts is to apply a higher torque (ft. lbs.) to the parts which decreases the likelihood of gasket leaks.

Eric

bjbuchanan · « **Reply #2 on:** January 28, 2014, 10:06:34 PM »

I personally don't buy the head nut gimmick. I say gimmick because of the low torque application on even HD studs combined with the fact there is a limited area the nut can take up. Not enough advantages

If the head area there was enlarged and the nut was a bit bigger with a bigger washer you could get better clamping force by that alone, or having more studs but that isn't practical.

Cars run much higher torque on the stud/nut and there still isn't a big aftermarket for the nuts unless you are making real power

timbo750 · « **Reply #3 on:** January 29, 2014, 02:01:18 AM »

Quote from: bjbuchanan on January 28, 2014, 10:06:34 PM

I personally don't buy the head nut gimmick. I say gimmick because of the low torque application on even HD studs combined with the fact there is a limited area the nut can take up. Not enough advantages

If the head area there was enlarged and the nut was a bit bigger with a bigger washer you could get better clamping force by that alone, or having more studs but that isn't practical.

Cars run much higher torque on the stud/nut and there still isn't a big aftermarket for the nuts unless you are making real power

That's more or less what I was thinking in the back of my mind, the issue always seems to be mentioned that the studs either stretch or break but the studs are never mentioned to be a problem.

dave500 · « **Reply #4 on:** January 29, 2014, 02:28:48 AM »

ive never bought into the heavy duty stud stuff either,im sure the stock ones in good un pitted condition will take a little more winching down?we still hear of quality heavy duty stud failures though on more or less stock engines more so than the stock part breaking?i think half the heavy duty stuff people buy is crap?

bjbuchanan · « **Reply #5 on:** January 29, 2014, 02:23:56 PM »

My stock studs took 18.5 lbs after initial tightening and then rechecking after 2 days (values hadn't changed). Supposedly mine were supposed to twist off or stretch, idk, but I know I am definitely up near the threshold.

I think that HD studs atleast are a bit more important for worked 750's more so than other bikes. I have 500 miles on a stock stud ebay 836, cheapo gasket set, home cleaned head and ports. Not a drop of oil anywhere so far and I even handmade my valvecover gasket. Results may vary but I think the little bikes don't need HD studs.

I even had to hand straighten two studs I accidentally bent a little, shhh

MRieck · « **Reply #6 on:** January 29, 2014, 04:12:40 PM »

The heavy duty nuts I sold and the Kibblewhite ones CycleX sells are taller and have more thread purchase. Material is better too. I have pulled the threads out and distorted the threads of OEM nuts with HD studs. The flange area is thicker and larger which helps distribute load too. I have seen threaded metric rod used for studs....it appeared to work too.

alacrity · « **Reply #7 on:** January 29, 2014, 10:21:18 PM »

Actually I'd be curious to hear what the (more experienced) guys here think about re-use of OEM head nuts. I'm about to do a top end on a cb500 that has been reassembled and torqued twice (that I know of).

Visually, the nuts seem fine...

PeWe · « **Reply #8 on:** January 30, 2014, 01:27:31 AM »

I reused the OEM head nuts several times without any problems. At least 5 times head was off. (maybe 7). (4 of them I torqued to 28Nm) Now new OEM nuts that look weak, like 8.8 when they are shiny.
10.9 or 12.9 should feel better when they withstand much higher torque.

Do not apply too much torque on the HD studs.
They can snap which they have in several threads in this forum. Snapped at around 20-22 ft lbs. The torque wrenches might not been exact calibrated so the torque might have been higher. (+5%= 1ft lbs)
HD studs will not flex as much as OEM studs and probably keep the applied torque much better. I would not torque more than 20ft lbs, 21 with a good calibrated torque wrench.
Kibblewhite state 22 ft lbs as max.

EDIT:
Info found on Internet.
I see now that M8 grade 8.8 has max 24Nm in torque... hooops!!! 17.70 ft lbs HD nuts MIGHT be necessary. For flange nuts +10% when it has more friction taking the torque.
17.7x1.1=19,5 ft lbs

flybox1 · « **Reply #9 on:** January 30, 2014, 07:36:33 AM »

Quote from: MRieck on January 29, 2014, 04:12:40 PM

The heavy duty nuts I sold and the Kibblewhite ones CycleX sells are taller and have more thread purchase. Material is better too. I have pulled the threads out and distorted the threads of OEM nuts with HD studs. The flange area is thicker and larger which helps distribute load too. I have seen threaded metric rod used for studs....it appeared to work too.

How tall.. if i might ask?
Anyone have some HD or kibblewhite ones on hand to measure height?

lucky · « **Reply #10 on:** January 30, 2014, 01:43:01 PM »

Quote from: alacrity on January 29, 2014, 10:21:18 PM

Actually I'd be curious to hear what the (more experienced) guys here think about re-use of OEM head nuts. I'm about to do a top end on a cb500 that has been reassembled and torqued twice (that I know of).

Visually, the nuts seem fine...

Not a problem.

flybox1 · « **Reply #11 on:** January 31, 2014, 07:37:06 AM »

Quote from: flybox1 on January 30, 2014, 07:36:33 AM

Quote from: MRieck on January 29, 2014, 04:12:40 PM
The heavy duty nuts I sold and the Kibblewhite ones CycleX sells are taller and have more thread purchase. Material is better too. I have pulled the threads out and distorted the threads of OEM nuts with HD studs. The flange area is thicker and larger which helps distribute load too. I have seen threaded metric rod used for studs....it appeared to work too.
How tall.. if i might ask?
Anyone have some HD or kibblewhite ones on hand to measure height?

bump...
anyone know how tall the HD nuts are?

PeWe · « **Reply #12 on:** January 31, 2014, 08:59:16 AM »

Alternatives on ebay? Grade 10.9 must be stronger than OEM, or?

I think I will replace my OEM with similar nuts but 10.9 grade or more
I measured my expensive shiny nuts delivered 1 by one 1 in Honda plastic bags.
Width: 16,8mm
Height: 7,7mm
Wrench size 12mm

These must be an upgrade if the torque is more than 17,7 ft lbs (+ 10% for flange nuts) that is the general limit for 8.8 grade. Maybe that's why Honda specify 18ft lbs as max torque for CB750 head?
http://www.ebay.com/itm/10-M8-1-25-Pitch-Hex-Head-Flange-Nuts-Phosphate-Metric-10-9-Grade-Bolt-/130593854198?pt=Motors_Car_Truck_Parts_Accessories&vxp=mtr&hash=item1e680012f6

EDIT:
Or finding higher nuts and use separate washer, all in 10.9 grade.
http://www.hoffmann-tools.com/Spanntechnik/Hohe-Mutter-M8-AMF.html#.Uuzbs7TxdhI

EDIT: This one if the height is OK (and threads)
http://www.hoffmann-tools.com/Spanntechnik/Bund-Mutter-M8-AMF.html?listtype=search&searchparam=bundmutter#.UuzarrTxdhI

EDIT again:
The magic word to search for: DIN6331 M8

PeWe · « **Reply #13 on:** February 10, 2014, 08:30:14 AM »

Got my standard DIN6331 flange/collar nuts today. Forged 10.9 grade.
search DIN6331 and you'll find.
M8
18mm - outer diam
12 - total height (with 3.5mm thick collar incl)
13mm tool

I have not installed these yet. I'll cut the frame first so I can remove all parts (Frame mod kit), replacing studs included.

Tested thread on an APE HD stud. Same fit as an old HONDA OEM nut.
The other side of the stud has a very nice tight fit, no play at all. Longer threads are made for the case.

Thinner washers might be needed. I have spring washers in my screw, bolt, nut and washer box.

timbo750 · « **Reply #14 on:** February 14, 2014, 04:04:20 PM »

PeWe thanks for the info. I have done a search and there are actually a lot of suppliers, all I have to do is finx one in Aus

Project 1 CB750 - http//forums.sohc4.net/index.php?topic=126864

PeWe · « **Reply #15 on:** February 15, 2014, 06:56:26 AM »

I'll report with photos when I have tried the new higher nuts. I hope it will be no problem with the height of the nuts and cam towers.

Old Scrambler · « **Reply #16 on:** February 15, 2014, 07:28:44 AM »

Take a look on the High-Po page under Salt Racer.................by Johno of Australia. Near the last page of current build is a picture of installed nuts.........with a little trim to the cam-tower for clearance.

MCRider · « **Reply #17 on:** February 15, 2014, 08:10:16 AM »

Reusing OEM nuts on a stock engine is OK, for sure, done it a hunnert times. Using stock nuts on HD studs works too, though my built motors have never been as built as some.

On current motor (888 with mild cam) I love the HD nuts supplied by Mike Rieck (Kibblewhite?). They don't need any clearance, are 13mm hex with a broader flange and slightly taller than stock. Gives a really good feel.

I used the protocol I got from Ken at CycleX to tighten the nuts: Take down to x+ torque, then release. Then take down to x++ torque, then releasse, then take down to torque x+++, then release, 5 times. Each iteration brought the nuts a little further down the stud. (APE studs). The final brought the threads to perfectly flush with the top of the nuts, very nice. I ended at 20ft lbs.

Ken says this "burnishes" the threads together, making them a matched set per nut. Makinig up for manufacturing tolerances.

I think I have pics if anyone cares, probably in build thread below, back to the summer.

KrautKoffin · « **Reply #18 on:** February 15, 2014, 11:54:02 AM »

Where can I get these taller nuts in the states? I've got a 550 going back together soon.

MCRider · « **Reply #19 on:** February 15, 2014, 12:05:44 PM »

Quote from: KrautKoffin on February 15, 2014, 11:54:02 AM

Where can I get these taller nuts in the states?

CycleX, MRieck, I think DynoMan may have them, maybe APE. I think Kibblewhite may be the manufacturer. They are.

http://www.cyclexchange.net/Engine%20Parts%20Valve%20Trane.htm

Advertised for 750s, don't know about 550s.

750cafe · « **Reply #20 on:** February 16, 2014, 07:59:34 PM »

What is the pitch on those nuts? 1.25 or 1.50?
I believe that I may have a source for a much better price.

Eric

754 · « **Reply #21 on:** February 16, 2014, 10:14:31 PM »

Would not hurt to. Work over the flanges, with a stone , or a figure 8 pattern on sandpaper(over glass or other flat surface). ...... Just to make sure the bed down nice..

bert96 · « **Reply #22 on:** February 17, 2014, 05:56:48 AM »

M8X1.25

Bert

Sent from my HTC_Amaze_4G using Tapatalk

750cafe · « **Reply #23 on:** February 17, 2014, 07:38:01 AM »

Thank you Bert. I will see if they are open today (Federal holiday)

Eric

750cafe · « **Reply #24 on:** February 17, 2014, 09:47:19 AM »

Remarkably, they are open today!
I will have to order a quantity from the New York warehouse and pay the shipping but, I would be able to sell 16 Grade 10
8 X 1.25 HD flange nuts for $13.00 including shipping.( I would probably just pack 18-20 in case one gets lost or screwed up somehow.)
I do not have the dimensions yet. Any interest before I order a great quantity of these?(Only way to get a good price on them.)

Eric

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Author Topic: Head Nuts - Standard or ????? (Read 4921 times)