The back bolt on Center locks

[CM/FFdriver]

Hello All.

I'm asking about the back bolt on the center lock and what would be the torque spec's for that back bolt if any info would be great.

Thank you

Ben

[billtebbutt]

Depends on the bolt, and to a lesser extent, the hardware.

When I restored my March 78B, I had ARP make the stub axles for a 3/4" fine thread, with ARP nuts (a bunch they had left over from an Indy Lights project I was told) to hold the wheel on. I used 180 lbs/ft torque and red loctite to hold the axle into the hub assembly, never had an issue. And the wheel nut took 140 IIRC

I guess what i am trying to say, as a non-engineer, is that the whole ****eroo needs to be thought of as a unit. If that makes any sense.

On my RF 90 (not centrelock, but easily converted with a longer stub axle), the "backbolt" takes 180 plus red loctite.

cheers,
BT

[S Lathrop]

I have used 150 to 180 ft pounds for the bolt where it goes through the bearings. I use 130 to 150 for the wheel nut so you numbers are good.

But I would not use Loctite. The torque across the wheel bearing is critical and you can not check that torque if you use Loctite. I had Z16 that the nut on the rear CV joints which controls the tension on the rear wheel bearing, where the owner never removed the nut to checked the torque, ruin not only the bearing but the spindle and the upright. The nut was very hard to remove and I will bet that if I had checked the torque, it would have been tight enough. But things had yielded over time and both rear corners were self destructing.

The torque on that nut that controls the tension on the wheel bearings should be checked before every race or no more than 2 races with out checking. And if you like to use Loctite, that means remove the nut, clean the threads and re torque the nut with fresh Loctite.

[CM/FFdriver]

I have used 150 to 180 ft pounds for the bolt where it goes through the bearings. I use 130 to 150 for the wheel nut so you numbers are good.

But I would not use Loctite. The torque across the wheel bearing is critical and you can not check that torque if you use Loctite. I had Z16 that the nut on the rear CV joints which controls the tension on the rear wheel bearing, where the owner never removed the nut to checked the torque, ruin not only the bearing but the spindle and the upright. The nut was very hard to remove and I will bet that if I had checked the torque, it would have been tight enough. But things had yielded over time and both rear corners were self destructing.

The torque on that nut that controls the tension on the wheel bearings should be checked before every race or no more than 2 races with out checking. And if you like to use Loctite, that means remove the nut, clean the threads and re torque the nut with fresh Loctite.

Thank you for the info my mind is at Ease.

Ben

[Charles Warner]

Lola S2 used 180 and 125.

Ralt RT-4 used 180 and 140.

One critical factor is to NOT retorque your wheels when you come in from a session to see if they loosened. The only thing you should do to them is loosen the nuts, or leave them alone until they normalize.

[old 59]

or leave them alone until they normalize.

Am I to assume you mean cool down to ambient temperature?

[Charles Warner]

correct