Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Time to talk to your nuts?

How tight should your wheel nuts be? My 4/4 Owners Handbook simply says
“Refit the spanner to the nut and strike the lug in correct direction to tighten.”

This tool has been mentioned on TM in the past and I recently bought one for my hub nuts. It is advertised as a “high-quality aluminium special tool.” Part number: 479748.





Here is the link https://www.scparts.co.uk/sc_en/special-tool-1-79772.html

It is a dirty great big 3/4" drive socket for 42 mm octagonal spinners. I bought a ¾” to ½” adapter so I could use it with my big torque wrench. For fitting or removing my stainless wires I have always used the hammer and flat spanner which came with the car but I have become increasingly nervous. So far, I have not hit a wing or wheel but it can only be a matter of time!

I was curious to know what the hammer and spanner had achieved the last time I replaced the wheels, so I marked each wheel nut relative to a spoke. I backed off each nut a bit and found the torque required to get it back to where it was. One nut required 180ftlbs, one 190ftlbs and the other two were off the scale, so greater than 220ftlbs. The hammer and flat spanner are obviously very effective but also it seems all too easy to over do the amount of torque applied.

After some thought I replaced the wheel nuts using 60ftlbs torque, re-marked the nuts and went for a short spin. Back home, I found one nut had tightened itself by about half a centimetre at its circumference, confirming that they really do self tighten! The rest had stayed put. My torque wrench is calibrated in one direction only and I probably forgot to change the head of the wrench over when I changed sides on the car. I increased the torque to 80ftlbs and the nuts have not moved since. It is now much easier to remove the wheel nuts using just a normal breaker bar with the socket and to replace the nuts using a torque wrench. No heroics with hammers or long bars and no danger of body or wheel damage. I may try 70ftlbs next time.

The socket costs £48 inc. VAT and with postage it came to £60.95 which is expensive. However, it is probably much cheaper than body and/or wheel repairs. How much is peace of mind worth? No financial interest etc.

There seem to be a wide range of recommended torque settings for knock on or hex spinners, the very nature of their use with a hammer plus the self tightening effect probably explaining why. All figures are well above 100 ftlbs though, with Lotus recommending 200-220 ftlbs plus a check after 15-20 miles.

The 60 or 70ftlbs you mention is definately in the wrong ball park for a single nut fixing though, as your experience has confirmed.

FWIW I use a long MG style pressed steel tool for my two eared spinners, which fits in my tool tray. A carefully calibrated shove of similar magnitude to fit or release seems to work fine for me.

OldTimer

Scroll down to their recommendation.

I can't imagine the torque setting for these nuts to be anywhere near critical since they self-tighten. I am firmly in the "Whack 'em hard with a big hammer" school, in over 20 years I've never come close to whacking anything that shouldn't be whacked.

Agreed its not critical Tim, but there has to be a sensible starting point, especially if relying on the self tightening effect. I'm thinking spline wear, safety issues aside!

My Land Rover has five nut wheels each of which are at recommended 75ftlbs for example. Note also the Old Timer link that Ice Pack offered suggests over 350 ftlbs in some cases, although that does seem excessive.

But the way the Landrover wheels are driven is different.

The drive there is through the hub to the wheel relying on the clamping force provided by the wheel nut torque

On our wheels the drive is provided by the splines so the nut is only there to stop the wheel falling off and to centre it on the cone.