Wheel nut torque?

[Jeff Jagusch]

We plan to run our Lola T644 next weekend, but it's the first FF I've ever owned with center lock wheels. Can anyone help with the proper torque?
I'm pretty sure it's essential to keeping the wheels on
Fwiw, the nut is 3/4" NF

Thanks

Jeff

[SStadel]

Start with 115. If they fall off, go higher.

[Jeff Jagusch]

Maybe I'll start higher and if the shaft breaks I'll go lower

Funny thing, last weekend we were at Blackhawk, and my dad said "remember that guy that ran two cars a Mazda and Club Ford?"

Thanks
Jeff

[DaveW]

I use 120 lb-ft on the centerlocks (3/4-16 thread) on my F2000.

[EYERACE]

I use 150 lbs on my 94 VD FC OZ wheels or Technos

DO YOU HAVE THE SHAFT ENDS DRILLED SO AS TO RUN A RETAINER PIN ??

[Jeff Jagusch]

Thanks Guys,
I think I'll try 120
And yes they are drilled for pins

[rickb99]

I use 120 lb-ft on the centerlocks (3/4-16 thread) on my F2000.

That sounds about right then shave down the wheel nuts to where you can get the safety pin in at that value.

[SStadel]

Whatever Dave says is gospel! Your Dad remembered me? Crap that was 26 years ago! Hard to believe I'm only 39.

[Jeff Jagusch]

Strange coincidence for sure, but he really did ask about you. Those were fun times back in the '80's. We have been mostly vintage racing since then. Good thing MC let us race at 10 years old, right?

[Modo]

You got it right, start with low and go higher, stubs are custom built so not much overkill/checking built into stub, 95lbs and if that works (check after session) my tatuus wants 93 as specified and I do 95-100, usually 100, the old reynard wanted 110 but sometimes was afraid to do that looking at the piece, good luck ....

course, DaveW's stubs are american built, may be stronger!! ......

more important!!!, make sure your stub-bearing nut/nuts/bolts are torqued or no tightening of the wheel nuts will keep them on ..... been there

[formulasuper]

That sounds about right then shave down the wheel nuts to where you can get the safety pin in at that value.

Or if your axle stubs are longer like on my RT5 you should use steel 3/4" I.D. washers to fill the gap between the safety pin hole & the nut to eliminate any possibility of the nut backing off & allowing the wheel to become slightly loose, which is not a good thing.

[Jeff Jagusch]

Thanks Scott,
While my axles are drilled, the pins are at leas 1/2" from the nut
I might turn some spacers to tighten the gap

[formulasuper]

Thanks Scott,
While my axles are drilled, the pins are at leas 1/2" from the nut
I might turn some spacers to tighten the gap

Ya, mine are like that also when using my Jongbloed wheel set that has thinner center sections than my BBS's, so I need diffent thickness spacers for the two sets.

[racersonly]

I remember a MC banquet where one member was awarded 5 championship trophies. What was it, 3 Autocross, 2 wheel to wheel?

[DaveW]

I use 150 lbs on my 94 VD FC OZ wheels or Technos

DO YOU HAVE THE SHAFT ENDS DRILLED SO AS TO RUN A RETAINER PIN ??

I run retainer clips also. Having said that, the only times (maybe 5 or 6 instances) I have had wheels come loose were when there was something wrong with the fit, in my case, mismatched inner radii not allowing the wheel to seat flat on the hub. Other than that, I have never had one come loose.

[marshall9]

retainer clips=reminder clips. Take them out after each session, and install them after wheels are torqued. Reminds you that it was done.......

[rickb99]

retainer clips=reminder clips. Take them out after each session, and install them after wheels are torqued. Reminds you that it was done.......

Wish I'da thought of that. Back in the day, on Saturday I sent my son out on track at Portland International for a qual session. Then standing in the grand stands watching him, I suddenly turned to my brother and said "my god, I forgot to torque the wheel nuts!". But he made it through the 40 minute session with the wheels torqued to about 70 Lbs/Ft. That never ever happened again.

[DaveW]

retainer clips=reminder clips. Take them out after each session, and install them after wheels are torqued. Reminds you that it was done.......

We use them for that, also. Torque a wheel, put in the clip, go on to the next wheel...

[Charles Warner]

You got it right, start with low and go higher, stubs are custom built so not much overkill/checking built into stub, 95lbs and if that works (check after session) my tatuus wants 93 as specified and I do 95-100, usually 100, the old reynard wanted 110 but sometimes was afraid to do that looking at the piece, good luck ....

Not sure I understand the comment about "overkill/checking built into stub." If made from proper material and with proper techniques (rolled threads) this comment doesn't make sense. Are you saying that stub axles made outside of the US are somehow inferior?

And, how do you check the torque after a session? If you simply put the torque wrench on the nut and try to tighten it more to verify the torque you are doing nothing. You might try a reversing torque wrench but even then it means little. The torque values are for those disparate metals tightened at ambient temperatures. After a session the different materials expand/contract at different rates. The only thing you can do by tightening the nuts after a session is take the chance of stretching/damaging your axles/nut assemblies. Use the proper torque as installed by an accurate torque wrench (you have had yours verified, right?) and go racing. When you come back in either let the wheel assemblies normalize or loosen them.

[Modo]

good points ........... clarification I hope ......... my stub axles for my 83 reynard looked iffy to go up 110 or 120 with the 3/4 thread, think i successfully used 105 lbs, definately wouldn't try 120lbs, I meant check for loosening before the next session to see if your torque value was ample, not recheck torque immediately, good point, may confuse someone .....

as far as the overkill/checking statement, poor choice of words .......I'm sure a auto manufactures stub axle has gone thru a million design reviews and failure checks and might even have rolled threads, dunno, small race shop I'm sure builds the piece well, but not necessarily the same type of scrutiny and weight is always a concern

[SStadel]

Jack, it was only 4. Two autocross championships and two wheel to wheel championships in 1988. The Club Ford championship came down to the last lap of the last race. Great stuff. I think Walter Payton won his first S2000 race in the same race group.

Jeff, one other thing. I always, ALWAYS torque the wheels in the air. Any kind of bind on the ground could give you a false torque. We can't do that with the Atlantic at 600 lb/ft but 115 is not a big deal in the air.

[EACIII]

When I had a Lola T-644 I used 108 and retaining pins. But the thread was not 3/4", it was a metric something that I don't recall now.

Ed

[CJD]

Jeff, I torqued my Lola T644 wheel nuts to 115 foot/lbs.

v/r Chris

[problemchild]

Torque table for 3/4-16 shows Grade 2 -138, Grade 5 -223, and Grade 8 -315. If your wheel stud cannot handle 115-125 ft-lbs, you have other problems.

[Brian]

"Torque table for 3/4-16 shows Grade 2 -138, Grade 5 -223, and Grade 8 -315. If your wheel stud cannot handle 115-125 ft-lbs, you have other problems. "

My thought exactly! I used new nylock nuts every second weekend or so, and simple hairpin clips. I was the only one who did up the nuts (I hid the socket), and if the wheels were on they were torqued (just my method of remembering). My thoughts on clips and such has evolved lately. I now think of them (and safety wire ) as "don't lose the expensive bolts/wheel nuts/whatever" rather than actually doing anything positive to the joint. At Summit Des Legends this weekend (saw Charles W. but didn't introduce myself) I saw a lot of clips on stub axles and actually spent some time trying to figure out how a little spring clip was going to help a 18" wide 26" tall (or whatever they are) F1 wheel and tire stay on and do anything positive...

Mind you it was cool to see 13 F-1 cars, an Audi R8, and seemingly countless other amazing cars up close and with full audio...

Brian

[Steve Demeter]

Now is the torque dynamic or static??

They are very different.

I use dynamic. Think of tightening them in one motion without stopping. Kind of slow but moving at a steady rate.

Torque infers tension in the bolt by measuring the friction required to turn said fastener.

That is why really serious guys do not measure rod bolt torque, but bolt stretch instead.

Dynamic coefficient of friction is lower than static. If you torque a wheel nut to 120, it will take more to start loosening it up because it is now seeing the static coefficient of friction.

We ought to call them friction wrenches.

[Charles Warner]

my stub axles for my 83 reynard looked iffy to go up 110 or 120 with the 3/4 thread, think i successfully used 105 lbs, definately wouldn't try 120lbs,

So, you "looked" at the stub axles and determined they could withstand 105 ft/lbs of torque but not 120? That is some calibrated eyeball. If there is any doubt at all that the axle is sound a prudent sort would replace it.

I'm sure a auto manufactures stub axle has gone thru a million design reviews and failure checks and might even have rolled threads, dunno, small race shop I'm sure builds the piece well, but not necessarily the same type of scrutiny and weight is always a concern

Richard, Steve or Dave (or John Taylor or Doug Learned) can shed much more light on their production processes and quality control. In my mind it is probably at least on a par with the auto manufacturers.

[formulasuper]

Now is the torque dynamic or static??

They are very different.

I use dynamic. Think of tightening them in one motion without stopping. Kind of slow but moving at a steady rate.

Torque infers tension in the bolt by measuring the friction required to turn said fastener.

That is why really serious guys do not measure rod bolt torque, but bolt stretch instead.

Dynamic coefficient of friction is lower than static. If you torque a wheel nut to 120, it will take more to start loosening it up because it is now seeing the static coefficient of friction.

We ought to call them friction wrenches.

And is the fastener torqued dry or lubricated ? They are different also.

[Ralph Z.]

I used 125 lbs on my 94 and 98 Van Diemens FF.

[R. Pare]

Richard, Steve or Dave (or John Taylor or Doug Learned) can shed much more light on their production processes and quality control. In my mind it is probably at least on a par with the auto manufacturers.

Well...... not really. Yes, we have, in a couple custom cases, gone nearly all out on stub axle manufacture (4340, RC 50, double drawn, shot peened & polished), but for an FC, it really is not necessary if cost is something you are trying to keep under control.

For many years we used B7 rod from McMaster. B7 is a bit less strong than a Grade 5 bolt - about 125kpsi. We used them both front and rear with zero issues over 30+ years. Rear stub axles, when we were still using the Dasher outboard CV, were made from 4340 and heattreated to somewhere around RC46-50.

Really, unless the hub design is bad, or something else is going on that massively increases the loading, threaded rod of that strength is going to be pretty bulletproof. Recommended torque for a 3/4-16 high-strength bolt is 400 ft.lbs to induce 100kpsi stress in the threads ( per the Unbrako catalogue), At torques 1/3 or so of that, even the B7 rod is not stressed all that much.

Yes, you can indeed make hub rods to much higher specs - 4340 or 300M - and even max things further by rolling the threads instead of cutting them, polishing, shotpeening, etc - but for these cars all that is way overkill for the operating loads.

So, unless your stub axles are really junk, torquing them to 120 is not an issue to worry about.

Last note : fatigue is still an issue. If your stub axles are 25 years old, it may be a good idea to replace them.

[rickb99]

And is the fastener torqued dry or lubricated ? They are different also.

Most quality torque tables give you both dry and 'wet' torque numbers.

[Modo]

I did go up to 120lbs once FG, cracked the shoulder on the 83 reynard front stub ....... you got it though, 20-25 years and three logbooks is too old for key part ......... however 105lbs kept the wheel nuts tight and the wheel attached to the car so we settled for that ....... got a new one after the crack, nice piece from Larry O ...... also heard of a failure on another reynard, don't know if it was old or over-torqued, homebrew or what, but the person was in for a ride and a heads up for me!!! ........ did steve, richard, or doug used lathe threads as opposed to rolled, how does the torque for them compare to the various torque tables?? ........

Tatuus manual ---- 130-140 Newton-Meters ............. 95 - 103 ft lbs Oh, ...18mm 1.5 stub thread, smaller than 3/4...... just fyi

[R. Pare]

We just use cut threads - rolled threads cost too much ( didn't have the equipment in-house). If I really wanted something to last damned near forever, I'd have the threads rolled. However, even rolled threads will fatigue over time.

I would expect the induced stresses in a rolled thread to possibly be lower for the same torque reading because of the more-rounded thread root. However, the better finish on the thread flanks may produce less friction, allowing the nut to turn a bit more for the same torque, stretching the stud more, so it may be a wash. Never looked up the possible differences in how it affects torque, so I'm just guessing.

Many of the stub axles on cars that used the Dasher or Rabbit outer CVs were built with a big stress riser on the inside : the sharp inside corner that is left by the tap drill. When I discovered that ( in some stubs that someone else built), I designed ours to get rid of that problem ( a difference in the tooling and how the hole was machined) . Never had another one break.

[PRS82F]

I used 105 on my T644 with factory stub axles/retainer cups and Compomotives. The stub axle nut was 120. Which is 15 more then the Fiat spec for the bearing (it is an X1/9 brg) and it didn't make any sense to torque the wheel nut more than the axle.

[HayesCages]

Reading through all of this and though what the heck:

On our (old) Argo FC with lathe cut threads on the 5/8" axle studs (not under-cut at the thread/shaft juncture - but plan to do it) we use 130. At some point last year I did a calculation and that's what we ended up with. It's well below the materials (most likely 4140) yield point so makes us happy.

As for the nuts: the chassis came with some sort of nyloc from the UK. We've tossed those in favor of NAS 6 point nuts. They come pre-lubed so have moly-based dry lubricant on all sides reducing face induced friction.

Bad part about the Argo's design is that there is no way to drill for a safety pin of any kind as the axle is too short. Suppose we could turn down the face of the wheel center though...not.

No obvious failures through the life of this chassis so far...but we carry spares for a reason don't we?

LH

[Charles Warner]

Half-height nuts?

[HayesCages]

.550" tall 6 pt., NAS1291-10:

http://coastfab.com/php/proddetail.php?prod=0898&cat=66

[Charles Warner]

Here is what Steve Johnson says about the use, and re-use, of jetnuts/kaynuts.

"reusing hardware. jet nuts are one time use hardware. really, no kidding. this isn't some lawyer language on the back of a paint can. on the second use they lose 75 % of their self locking ability and anything after that is the same as no lock nut at all. if you are using them more than once you are not being smart. if you are using them more than twice you are too stupid to be doing this work at all."

[HayesCages]

Ok, I guess I'm "stupid" then. I'll refrain from further comment on this subject and get back to making money so we can: Cheers!

[SStadel]

Hey Jeff. How about 115? LOL!