Do you torque wrench?

Curious about opinions on the use of torque wrenches in karting. Coming from the car racing world I am used to torquing important fasteners to spec. This is coming from a few bad experiences I had this past season with my CR125’s jug possibly not being tight enough or just inconsistently torqued. I had a fresh head gasket blow once (found the nuts inconsistently loose) and then the jug base cracked on my last race day when a stud broke, ending my season a few hours early! I have a good quality torque wrench but I believe it’s not giving me good clicks near the bottom of it’s range. I’ve seen a few karters torque things, others just use the “gutentight” method. Do you torque things other than engine components?

For those that use them, any recommendations on a quality low range torque torque wrench?

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I’d only torque the head down after post-tech inspection if I need to. Otherwise I leave the internal motor work to a shop. The rest of the kart chassis I tighten by hand.

So personally on a kart I don’t. Reason being (for me) is most of the bolts are way overrated for the application, so you can really wrench on them without them stretching or snapping.

Now for engines, you engine builder should use a torque wrench to reassemble your engine but, I’ve been to many engine builder workshops and I can count on one hand how many use a torque wrench. This, in my opinion, got worse with rotax and other spec series as the skill to rebuilding an engine just disappeared.

In terms of budget minded quality, probably a Pittsburgh Pro Reversible Click Type Torque Wrench? Maybe others have opinions. But it doesn’t matter if you don’t calibrate it annually anyway :wink:

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So you’re one of THOSE people… I see.

Just kidding, I used to have a full set of them but had some bad ones that caused snapped bolts and stripped threads :open_mouth:

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I only use a torque wrench for the engine head bolts. Everything else is just tightened using the finely calibrated torquing mechanism in my right arm.

My favorite is tightening the grub screws into the axle until they punch right through the axle wall. Then you know the axle isn’t going to slide.

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I’m with @tjkoyen on this one. Eventually, you tend to ‘know’ what ‘just right’ feels like. Still, for engine components, I do my best to tighten things to manufacturer spec. Exceptions for things like exhaust bolts or the clutch bolt for a 206.

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Ha, I just googled and assumed budget. Given any budget I would head towards an Atlas Copco product.

But having a production/process/manufacturing engineering at and engine plant I would add a word of caution, that a lot of people use torque wrench incorrectly. You really have to work you way up to to the click, not just yank for the click.

Looks like an old thread but i thought i would ask anyway as i have been thinking about how much torque to put into a nut and bolt… in particular wheel nuts, (Knuts) which are 3 x 10mm nuts on the OTK, i am sure i am over tightening them, however is there are recommended torque value? also the engine mount underneath the chassis, i am sure i am over tightening these bolts also? i could not find a guide on the OTK website so any generic advice would be great.

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Ugh Dugha repeat as necessary!

Just kidding depends on if its TQ is going to effect longevity or performance. I turn wrenches for a living, I pretty much can feel when something is right or wrong on non-critical parts.

-Your Pal
Ronald Swift

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I opened this really hoping that id have a good excuse to use the fancy snap on digital torque wrench that I got but it seems that i’ll never need it for my kart.

I use a torque wrench on everything.

There are typical torques for bolt sizes that can be easily found.

https://www.engineeringtoolbox.com/metric-bolts-maximum-torque-d_2054.html

Trying remember from my days writing manufacturing instructions for an engine plant. I think M5 was 6.5 lbft, M6 was 10.5 lbft was M8 was 35 lbft, M10 was 65lbft.

Typically speaking karting overtorque everything but as we replace equipment so regularly anyway, it typically doesn’t matter. Its not like we’re torquing a wheel nut for 20,000 km of running.

Engines I’d argue you should torque and get the torque pattern right and my experience is engine manufacturers do provide torque rating for headbolts/nuts etc.

Most I do by hand but if you want to torque the wheel nuts then OTK use 3 x M8. Typical torque for M8 is about 18ft/lb. You should always torque engine head bolts and exhaust flange bolts, especially on the X30. The X30 exhaust flange is rigid enough to distort the cylinder and should always be fitted when honing is performed. I have measured up to half a thou out of round in the cylinder just through tightening of this flange.