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The Anti-Roll Bar

YBantirollbar1c[1]YBantirolleyeboltc[1]

 

When MG updated the Y Type in 1951 to the YB specification, a great deal was fitted that had been used on the new TD sports car. It was logical to use the same items as this gives economy of parts with less items to manufacture.

The YA and YT used equipment from the now defunct TC. But one item that was special to type was the YB’s anti-roll bar. Given that only 1,301 YBs were built it is not surprising to find that today spares for this bit of kit are very scarce indeed.

 

When the YA’s independent front suspension was used on the TD, TF the anti-roll bar was not used. Then slightly modified it was used on the MGA and MGB but the anti-roll bar’s fixing was completely different.

 

YBantirollbar2b[1]So the YB has its very own, special to type, anti-roll equipment. Why fit it anyway? Well, the little sports TD and TF have such a low centre of gravity, their roll centre is low enough that the cars almost does not roll on corners anyway. The saloon body of the YB has a much higher roll centre, and the car will naturally lean over on fast bends. To try to limit this rolling on corners that all saloons do, a torsion bar is fitted across the front of the car linking the suspension units. This leaves them to act independently on bumps on straight roads, but enables the outer wheel on cornering to twist the torsion bar and use the inner wheels spring to stiffen up its own. In effect the torsion bar tries to lift the inner wheel, but it cannot so its adds some of the inner springs power to the outer unit. This will keep the car on a more even keel as it speeds round a bend. If it is overdone, how ever, it is possible to lift the inner wheel off the road and overload the outer, but not at the gentle speeds the YB is only capable of.

 

YBantirollbar3b[1]What goes wrong? Well, like virtually everything else on the Y Type, it is old age. The two split-rubbers that hold the anti-roll bar to the chassis forward arms rot away, but trimming MGB ones can provide a replacement, and NTG do stock new ones. The ‘eye-bolt’ link that joins the end of the anti-roll bar to the lower suspension wishbone corrodes away where the threaded stud lives inside the two top rubber blocks. It is the rubber that causes the rust as it holds the salty road water around this stud. If the stud wastes away too much it will eventually break. You will hear it whilst cornering as a loud ‘ping’ under the car and the car will lean a little more. If both ends break the bar will drag its ends on the road. This link has silent-bloc rubber cones at its lower connection. Again rust will eat out the housing and the rubber will be loose. These lower rubbers also permit salt road water to rust away the stud that faces forward from the lower wishbone. A ‘stud’ is a threaded bar.

 

YBantirollbar5bBut the biggest problem is that who ever designed the attachment to the spring pan did not allow for constant use of over 60 years! The bracket that bolts to the spring pan does so at a flat portion. This permits the pan to flex a little and eventually crack. On the later MGA and MGB the bracket fits through a hole drilled in the forward arm of the lower wishbone, a much stronger and rigid place. So the anti-roll bar’s link and the  channel-section bracket bolted to the spring pan need careful inspection, as does the area around the bolt holes in that spring pan.

 

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The cure? It is easy to drill out, tap a thread and screw in a replacement stud into the link, then welding it in. This can also be done to the bracket using a thicker stud. You can repair the spring pan again by welding it and adding reinforcing, or you can buy a MGB spring pan as it fits. How ever, the MGB’s pan will need drilling for your YB’s bracket. If everything then gets a thick coat of Hammertite and a dose of Waxoyl, it might last another 60 years.

 

Article by Neil Cairns.

 

Postscript : These days owners of the earlier YA often decide to bring their cars up to YB standard and add an Anti-Roll Bar and quite a few now add an MGA/MGB anti-roll bar instead.