My upgrade for M10 studs into toyota

[rockcrawler31]

I have posted this elsewhere too, so don't be smartasses If mods think this is too toyota specific please move it but i guess you could do this for other makes

I have done an upgrade to the studs/dowels on the 80 series axles on my cruiser. Some (not all) of us have had issues with them shearing with the larger tyres or higher torque/HP of engine conversions.

Some people run M8 Socket Head Cap Screws or ARP studs and been fine, and some have also drilled and tapped to the M10 studs that come on 100/79 series and later cruisers. However in my opinion these don't address the issue of why they snap in the first place, and i HAVE first hand blown these too. (M8 SHCS). The fault with the OEM system and upgrades is that the thread is adjacent to the shear plane(the weakest part of a stud). Also, technically, studs are best used in a tension application instead of shear like head bolts or big end bolts. After consulting with an engineer we decided that milling and machining a drive slug a la Dana axles was just not cost effective. His recommendation was to get the root of the thread beneath the surface of the shear plane by 1.5x diameter of the stud, in as close a fitting hole as possible to eliminate lateral fatigue moments.

I went home, did a LOT of measuring, and found a way to drill, tap, and COUNTERSINK the shank of an M10 SHCS into the hub.

Edit : Please note that this, and any other upgrade will be less effective if the axle housing isn't STRAIGHT. If you are constantly blowing studs, can't keep oil out of the bearings, or finding studs are constantly working loose you MUST check the straightness of the housing.!!

The conversion that i have done, i believe is a far better engineering result, isn't that hard to accomplish, and i have proven to work. At last years KOTR i pre-ran the course and due to a labelling mix up accidentally ran the whole course with the front locker engaged and the rear disengaged. Full wide open throttle, up hills, down hills, turning, you name it, all with the front locked in. The front hubs are the weaker of the two axles as it's impossible to upgrade the existing dowels or add more due to the cut outs on the hub. No failures AT ALL. Now if only the same could be said for my steering the next day....

Now some people may get on here and say that it's crap, or toyota vs. nissan horseshit. I don't give a flying fark. I'm not here to debate bullshit, i just wanted to give people both the option, and the information to do this if they wish. Although if any ACTUAL engineers wish to pipe up and correct me i'm fine with that.

I don't have pics at the moment, however i am endeavouring to get the wife to take some while i'm away. So if there's any confusing bits that need cleared up then please feel free to chime in and i'll do my best.

This will be a multi post thread as i suck at writing heaps of shit all at once, so please bear with me.

[rockcrawler31]

Firstly some notes :

1. You will be able to buy the same SHCS for both front and rear hubs. However due to the internal cavity differences between the two, the front screws will require a shorter thread section, so just buy enough for the job and then cut the ends off some for the front.

2. Keep spares. Even if it works perfectly and you never bust another stud again, the likelyhood of you finding the right sized stud at anywere in a hurry is virtually zero. So for a couple of bucks each, having a few spare (both front and rear) will come in handy.

Firstly i need to say that right now, i don't have the EXACT measurements as i'm sitting on a rig in India writing this. However this write up will give you the basic description and instructions, and i'll put up exact lengths later when i get home.

You will need

6 per wheel M10 x 1.5 (coarse thread) Socket head cap screws. Unfortunately these only come in 12.1 grade (8.8 would be better - a little bit of give). They need to have approximatey 30 to 35mm of shank depending on whether you use washers or not.
6 per wheel cone-lok washers (the kind that bite into the steel surface - spring washers are useless)
6 per wheel M10 cone washers from a 100/79 series or later landcruiser. You can get these reasonably cheap from a wrecker. Or steal them off your mates' truck

1 x 8mm drill bit
1 x 10mm drill bit
small bit of timber to use as a guage stop if you don't have an adjustable stop on the drill press
M10x1.5 starting tap, M10x1.5 bottoming tap and tap wrench
Cutting compound
Compressed air and brake cleaner to clean out the holes
Drill press (not essential but very recommended)
Mild or medium strength studlock (lets face it, if you shear a 12.1 stud it's not gonna drill and ezy out anyway)
Verniers (again not essential but pretty handy to check depths and double check what i'm about to write up)

I"m sure i'll think of other shit as i go and update here

[rockcrawler31]

Take one (or all) of the rear hubs off the vehicle and remove the bearings and rear seal. Remove existing studs, clean thoroughly and mount in drill press.

Measure with steel rule or verniers the distance from the mounting face of the hub, to the point inside the hub where the wall thickness decreases to allow a larger internal grease cavity. Subtract 5-7mm off this and WRITE IT DOWN (ask me how i know )

This will be the bottoming depth for the 8mm hole that you are about to drill in each existing stud hole. Carefully center each drill bit and slowly drill out the existing thread to bottom and continue on to final depth. Use cutting fluid and use the slowest RPM on the press to avoid burning the bit. Take plenty of time between holes and allow cooling time between. Trust me a snapped bit jammed in a hole sucks horse wang.

Edit note: on the inside of the hubs at the point where the wall thickness decreases there are two small cutouts on either side of that lip. You should account for this in your measurements if they align with the location of a stud hole.

[rockcrawler31]

Carefully measure the sum distances of

1.The axle flange thickness
2. The thickness of any washers you are using
3. The additional height created when a M10 cone washer from a 100 series landcruiser is placed in the cones of the axle. (sorry i'll add these to the required list shortly)

Write this measurement down, and subtract it from the shank length of the bolts. So for example if you have a 35mm shank, you may have a total thickness of 20mm to subtract. This means your countersink depth will be about 15mm plus about 2mm for good measure and clearance.

Important note - the M10 cone washers actually fill the cone recess in the axle better than the 8mm ones they were originally drilled for. The cone angle is the same but for some reason the M10 ones actually got all the way to the bottom of the recess when compressed. This means that an M8 washer must leave a gap?. Regardless, when measuring the stick-up height of the washer on the axle you must mount the two together in a vice so that the washer gap closes up and sits firmly seated as it would with a bolt pulling it down. If you do not do this then your sit up height (and ergo your countersink) will be wrong. Ask me how i know this.

[rockcrawler31]

If your drill press allows you to set a stop distance then use it to drill out the new holes with an M10 bit. Drill them out to the countersink depth you determined you needed. Do this slowly as the minimal difference between existing hole, and drill bit will mean it is easy to destroy the outer edges of the drill bit, requiring a resharpen. (Ask me how i know)

Alternatively i shaped a piece of timber down till it was the size i needed, drilled through it, and set the bit in the chuck with enough bit left sticking out past the timber. Instant stop guage. I made sure the bit was bottomed in the chuck so it couldn't move and just sized the timber to suit.

Use Cutting compound again to save drill bits. Remember, that will all these steps you will be repeating the process 24 times, or in my case with spares 36 times.

[rockcrawler31]

You will now have a hole with a smaller hole part of the way down.

Take the starting tap, and tap each hole to bottom. Use cutting compound, continually back the tap out one full turn after each two cutting turns. This will ease the process greatly, clear swarf from the cutter tips, and reduces the likely hood of a snapped tap. You wil NEVER get a snapped tap out if it snaps sub surface. If this happens just throw away the hub.

Remove tap, blow out swarf with a thin air nozzle. CAUTION - Flying swarf propelled by air WILL blind you if it hits your eye. USE PPE!!!!!!! You can also cover the hole and gun with a rag to control a lot of the flying swarf.

Mount bottoming tap and finish off the bottom of hole, use cutting compound again

Repeat cleaning process, Then final clean all holes with brakleen and air or any solvent that effectively removes cutting compound residue. The holes need to be clean so that the studlock works properly, and even if you don't use that, the residues will give false make up torque values.

[rockcrawler31]

You're nearly there.

The existing holes in the axle flange are actually almost 10mm anyway. You will need to clearance them with a 10mm bit to make sure. Be warned that same as before, the bit will DEFINATELY try to bite due to the near hole/bit size ratio.

Also the axle material is substantially harder, and it's recommended to have a COBALT BIT for this step.

With the hub still off the car, mount the axle and hub together. And screw in the screw/collet/washer assembl to check final fit and depth.

If all is good repack hub, and mount on car as per normal proceedures. Mount axle, and apply a small amount of light or medium strength studlocker to each bolt before fitting. Use a torque wrench and tighten to specifications for that bolt type and thread. I have the specs at home somewhere, but your supplier should be able to provide these specs when you purchase the bolts. (well any REPUTABLE fastener shop will check with their supplier for you). You can also get the appropriate adjusted specifications from the suppliers of the studlocker as this will change the torque values slightly compared to dry hole i believe. (no crude comments about dry holes)

[rockcrawler31]

The fronts are only marginally different. Same process but the hole depth is about 14 mm shorter. Take this amount off the screw threads, and this amount will come off the THREADED SECTION of the holes in the hubs. The countersink portion remains the same so long as the axle/hub flange thickness is the same.

Otherwise the process is exactly the same.

I'll add some info in an hour or two about upgrading the dowels, the home bell has rung and i got to get off the rig

[rockcrawler31]

Ok. Time for some pics. Unfortunately my lovely wife wasn't able to get any pics of the bolts completely out so i can do that later when i get home. She was also reluctant to email me any pics of her from our "cuddle time" so i suspect she may have sussed out what i was going to do with them

First is a pic of the rear axle on the car, conversion completed. Note that while the heads of the screws are protruding outside the OD of the hub, there is NO problems getting the wheel over them for mounting. You can also clearly see the upgraded dowel pins, as well as the extra two that i placed in the threaded axle removal holes. This was amost exactly the same process, measure dowels, make a stop guage, drill holes.



and in this image you can see where i got the depth for the first dowel i did wrong

[rockcrawler31]

Here are the front hubs. Same again, no issues getting the wheel over the assembly. However it is important to note that i now have to remove the freewheel indicator to check torque on the screws as they sit behind the flange. You can see how a normal hex head bolt would be impossible to get a spanner over, and SHCS's are the only way to do this.



Below are the spare hubs i have sitting in the shed. The screws have been backed out a little and you can clearly see the washers i have used in place of normal split washers. These have a cone profile that flattens out when tightened and teeth that bite the steel. Although i doubt that they would be harder than the SHCS' or the cone washers which would be spring steel. So really in my case i just did it because at the time i thought it was best. Note how the collets sit up a bit more than normal M8 collets would in the same hole. However i can assure you that they seat all the way down to the mating surface and fill the taper hole completely. There is NO loss of material on the axle flange, and there is still plenty of wall thickness left on the hub.

[80's_delirious]

Good write up. Was going to ask you for details on how you did this.

My 105series has a thick flat washer between hub bolts snd the tapered collet, different to 80series which had split washers.

[rockcrawler31]

Any time Dave.

The advice given to me by some fasteners suppliers, and a couple of engineers that i have spoken to is that spring washers are for just about all intents and purposes next to useless. The premise on which they work is bollocks and self defeating once the bolt is torqued up anyways. I've been advised that in a blind hole application (no nut) the primary and most effective locking mechanisms are

1. Correct selection of thread pitch, form, and length
2. Correct make up torque values and the correct method of applying the torque
3. Thread locking compounds
4. Wiring or lock tabbing.

[Z()LTAN]

Looking good. I did this to the front of the ute but ended up blowing out the side of the hub instead. Might have been the fact the after market hubs were of a lesser quality.

Good writeup bud

[rockcrawler31]

Looking good. I did this to the front of the ute but ended up blowing out the side of the hub instead. Might have been the fact the after market hubs were of a lesser quality.

Good writeup bud

That's very interesting to hear. Any chance of pics?

[KiwiBacon]

One thing I can't find in your write-up. Actual tightening torque.

The whole problem originally is not enough tension on the bolts which let the drive-flanges move. If you can stop the drive-flanges moving, then there is no problem.
Step one would be to put the strongest possible bolts in the original location and torque them to their yeild point. This alone could double the clamp load over what most people are running.
A lot of bolt tables will list torque at about 70% of yield. This is good if you want to remove and replace the fastener indefinitely, but gives away 30% of the possible clamp load. You can get almost 50% more if you are prepared to replace bolts after 2-3 removals.

Once you've upgraded to 10mm, have you torqued to the maximum strength of the new studs? If you are still running the same torque as before, then you will have gained nothing and are relying on the bending strength of the bolts. Which isn't a good idea.

M8 grade 12.9 can be safely torqued to 60Nm each, this gives a clamp load of approximately 3.6 ton per bolt.
M10 grade 12.9 can be safely torqued to 115Nm each, this gives approx 5.6 ton clamp load per bolt.

[CRUZAAMAD]

ive broken axle hub studs a few times.
and also broke the axles at the flange face another time, which im not keen on doing ever again at 750.. arb locker engaged.
expensive day out, but got nearly 27years out of them.

i dont think upgrading the studs is the best idea.
its only about 200bucks with genuine stuff to replace.
and wont leave you stranded if you break them on a landcruiser.
isnt their designed to be a weak link where its meant to be cheap to fix, than blow a diff, axles....done both!!.

i was considering putting the ARP studs in or m10, but it will break somewhere else where its harder to get too, more importantly more costly.

im over replacing studs but rather have a cheap fix now and then then an unknown repair bill down the track where the damage is growing elsewhere.

good write up rockcrawler.

[RED60]

One thing I can't find in your write-up. Actual tightening torque.

The whole problem originally is not enough tension on the bolts which let the drive-flanges move. If you can stop the drive-flanges moving, then there is no problem.
Step one would be to put the strongest possible bolts in the original location and torque them to their yeild point. This alone could double the clamp load over what most people are running.
A lot of bolt tables will list torque at about 70% of yield. This is good if you want to remove and replace the fastener indefinitely, but gives away 30% of the possible clamp load. You can get almost 50% more if you are prepared to replace bolts after 2-3 removals.

Once you've upgraded to 10mm, have you torqued to the maximum strength of the new studs? If you are still running the same torque as before, then you will have gained nothing and are relying on the bending strength of the bolts. Which isn't a good idea.

M8 grade 12.9 can be safely torqued to 60Nm each, this gives a clamp load of approximately 3.6 ton per bolt.
M10 grade 12.9 can be safely torqued to 115Nm each, this gives approx 5.6 ton clamp load per bolt.

Just a question here...if the torque figure you indicate here with m8/m10 grade 12.9 are used will the strength of the receiving female thread in the hub be exceeded..... you may have taken this into account but I am just asking if you did... in other words, if the figures you indicate are used is there a likelyhood that the hub will be stripped of thread when doing these up to these settings....

[rockcrawler31]

One thing I can't find in your write-up. Actual tightening torque.

The whole problem originally is not enough tension on the bolts which let the drive-flanges move. If you can stop the drive-flanges moving, then there is no problem.
Step one would be to put the strongest possible bolts in the original location and torque them to their yeild point. This alone could double the clamp load over what most people are running.
A lot of bolt tables will list torque at about 70% of yield. This is good if you want to remove and replace the fastener indefinitely, but gives away 30% of the possible clamp load. You can get almost 50% more if you are prepared to replace bolts after 2-3 removals.

Once you've upgraded to 10mm, have you torqued to the maximum strength of the new studs? If you are still running the same torque as before, then you will have gained nothing and are relying on the bending strength of the bolts. Which isn't a good idea.

M8 grade 12.9 can be safely torqued to 60Nm each, this gives a clamp load of approximately 3.6 ton per bolt.
M10 grade 12.9 can be safely torqued to 115Nm each, this gives approx 5.6 ton clamp load per bolt.

Thanks for your input kiwi, i was hoping you would read it and give feedback. I have in there somewhere written that you should find the appropriate listed torque values and use them. I"m away at work at the moment and am not able to access the chart i was given for them by the supplier. I am surprised by what you say (believe absolutely but surprised) since i thought i was doing the right thing and torquing my last M8 SHCS's to 70Nm as per supplier documentation.

Off the top of my head the current bolts are sitting at 105Nm ( inclusive of the medium threadlocker i've used) Can you please list any links to RELIABLE or peer reviewed documentation/specs on common fasteners and grades?

However, even with correct and maximum torque values, doesn't clamp force still only rely on friction of the mating surfaces as a holding mechanism? Isn't that negated by having gasket material present? Also this ties in with my belief about the straightness of the axle as EVERY tyre rotation becomes a bending/fatige cycle on the axle root and the clamping studs.

[KiwiBacon]

Thanks for your input kiwi, i was hoping you would read it and give feedback. I have in there somewhere written that you should find the appropriate listed torque values and use them. I"m away at work at the moment and am not able to access the chart i was given for them by the supplier. I am surprised by what you say (believe absolutely but surprised) since i thought i was doing the right thing and torquing my last M8 SHCS's to 70Nm as per supplier documentation.

Off the top of my head the current bolts are sitting at 105Nm ( inclusive of the medium threadlocker i've used) Can you please list any links to RELIABLE or peer reviewed documentation/specs on common fasteners and grades?

However, even with correct and maximum torque values, doesn't clamp force still only rely on friction of the mating surfaces as a holding mechanism? Isn't that negated by having gasket material present? Also this ties in with my belief about the straightness of the axle as EVERY tyre rotation becomes a bending/fatige cycle on the axle root and the clamping studs.

That's good.
The 70Nm your supplier listed is fine, I listed torques to give roughly 1000 MPa tension, the bolts can handle a little more than that and if grade 14.9 (1400x0.9 = 1260MPa yield) rather than 12.9 (1200x0.9 = 1080 MPa yield) they can take even more. Torquing them past yield once isn't a problem, but re-use becomes a concern.

Yes the gasket material does essentially lubricate the faces, you can make improvements by choosing a more rigid setting sealant instead of gaskets. If the tension in the joint is sufficient, the bolts/studs won't see any significant change in tension with the rotating loads. Bending loads will only come about if the drive flange can move and our goal is to make sure that doesn't happen. Bolted joints are pretty complicated things, you can spend a ridiculous amount of time on each of them to truely understand what is hapening.

For the strength of the threads, if you've got twice the bolt diameter then you're good. Rule of thumb being 1.5 times bolt diameter for equal materials, but in this case your bolts are likely stronger material than the hub.

The best reference for this application is the Unbrako Engineering Guide. It's quite heavy reading but has a wealth of information including measured torque/tension relations for their bolts. Unbrako being one of the worlds leading manufacturers of cap screws.
Here is one of them http://www.unbrako.com/docs/engguide.pdf" onclick="window.open(this.href);return false; they have several and it's a few years since I last pulled them down and archived them. Page 51 on that Unbrako PDF is where the technical guide starts.