Dear Welder Series…
I am building a prostreet chassis VW bug the front frame rails are 25.5″ outside to outside 2×3 rectangle need to get the proper width crossmember don’t know what to order.
Our crossmembers are ordered by track width. We call track width the distance from the wheel mounting surface of one rotor to the wheel mounting surface of the opposite rotor. In “real life” this dimension varies with Mustang II installations, depending on the brakes being used. A stock Mustang II (1974 – 78) has a track width of 56-1/2″. If stock, 4-bolt MII rotors are used on our 56″ kit, the track width would be 56-1/2″.
The frame should be at least 26″ O.D. to use our 56″ kit. If you plan to have a track width less than 56-1/2, the crossmember can be narrowed and the minimum frame width can be less by the amount taken out of the crossmember.
If you will use the 56-1/2″ track width, the frame should be made wider, at least in the crossmember area.
All of this is to say the 56″ crossmember is probably the one to order.
Thanks for looking at Welder Series parts.