Bolt Advice?

[aij29]

Hi Guys

I`m reconditioning a 2nd hand tow-bar for my Berlingo i`ve stripped it all down for de-rusting painting etc,
And need to replace all the mounting nuts/bolts washers etc.

I know i should use hi-tensile bolts but what grade is best? (I`m only towing a small trailer but maybe a small caravan in the future)

I would like to use stainless but i`m not sure if they are up to the job?

Thanks
Adrian

[swampy76]

Go for 12.9 mild steel

[docjohn]

You should be able to tell what the original ones were from the heads of the bolts that you've taken out. They may well be standard 8.8, which are remarkably strong and tough. If they're cap screws then they'll be 10.9; unlikely to be 12.9 and would be pointless anyway. Stainless is a bit of a minefield; unless you know that you can get an '80' class bolt then don't bother.

[dodgerover]

I'm pretty sure the calculations are online somewhere showing you could hang a London bus from an m6 nut and bolt! Don't use stainless though unless you can get it in the correct spec

[Rich]

As said, most standard towbar hardware is 8.8 BZP mild of a good quality. You shouldn't need to go mad with mega super high tensile.

[3point141]

+1 for the 8.8 route, anything else is utterly over-kill.

to illustrate, a single M16 of grade 12.9 would offer 14.84 tons to yield (19.14 Ton minimum Ultimate tensile strength)

[Deleted]

Go to you local caravan/ camping/ towing supplier that was you know you are getting the correct items and please make sure you torque them correctly and don't use any copperslip or tread lock if the nuts are Nylock.shake washers should be used if using non locking nuts.