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Get Yourself in Alignment - Part III

By Jim Lunson, tech committee

 

Ive been writing about getting the front end of an MG into alignment and getting aligned with the steering wheel. An item that is critical for all this to happen is to have a solid, secure front end suspension. To do this often requires the rebuilding of several components of the front end as the MGs are old, probably not properly greased, and the systems were not designed to withstand much of the road conditions encountered today. There are several things to look for in wear and tear in this area that must be addressed before a good alignment can be done.

The first step is to jack up one of the front tires while leaving the other one on the ground so the weight of the car holds it in place. With one wheel in the air, tug the tire in and outwards, grabbing it at the 6 and 12 o'clock positions. There should be no movement in this direction. Movement here indicates wear in the suspension or wheel bearings. If there is wobbling, the next step is to repeat this same motion while observing the workings from the front of the car. From here, you can see what is moving. If the suspension remains fixed doing this test but the wheel, and tire moves, then the bearings are worn and in need of adjustment. I covered how to do this repair in past articles.

If, however, the entire wheel system, including brake and hub assembly moves in and out, two places on the suspension need to be checked. This wheel assembly is anchored at the top by the shock absorber arm and at the bottom by the horizontal pivot fulcrum at the outboard end of the A-arms. See what is moving as the tire moves in and out in the vertical direction as both are critical to hold the assembly rigid.

Shock Absorber - The shock absorber on all MGs (except for TCs) has a horizontal shaft that holds two long lever arms which reach over and attach to the top of the wheel assembly. In addition to providing the shock dampening, the shock provides the bracing to hold the top of the wheel assembly rigid. First check to see that the bolts holding the shock down on the cross member are tight and the entire shock is not moving. Then check to see if the rubber bushing between the shock arm and wheel assembly are firm. Tightening the shock absorber bolts is an easy fix, removing the horizontal bolt that connects the shock end to the wheel to replacing the two rubber bushings is not so easy but must be done if there is movement here.

These two bushings are rubber and wear away over time. Replacement requires removing the horizontal bolt at the end of the shock arm. This bolt has a flat side on the head that jams against the shock arm so it will not rotate and getting it extracted can be impossible. Ive found that unless the bolt easily slides out, it will never come out and must be cut off with a hacksaw. And this cut requires two cuts, one on each side of the wheel anchor kingpin so the two shock arms can be lifted up. Then the bolt pieces can be driven out with a hammer and punch. Once out, a new bolt replacement and bushings are available. I recommend inserting the new polyurethane type bushings in place of the original rubber as these last much longer. And use anti-seize on the new bolt in case you want to remove it later.

Rarely, movement in this area comes from the shaft in the shock absorber. If this is the case, replacement of the shock absorber is needed, usually also requiring the bolt noted above to be cut to be able to remove the old shock where the arms attach to the wheel assembly.

Bottom Fulcrum Pivot/A-Arm - The bottom pivot pin system is one of the weakest links on MGs, is usually the first place movement shows up in the suspension system, and an area that can become dangerous if not repaired. This fulcrum pin runs horizontally, from front to back of the car, at the outboard end of the a-arms which extend on either side of the spring pan. This connection links the car frame, spring pan, and wheel assembly together and ties them onto the lower end of the kingpin wheel assembly. Rotation of this fulcrum pivot is constant every time the car bounces on any sort of bump and all the weight of this corner of the car is carried on it. This pin consists of a large bolt running through a brass sleeve in the bottom of the wheel assembly.

Constant clean grease lubrication of this pin is critical to avoid wear and with the weight of the car on it, grease squeezes out rapidly. Without grease, the bolt seizes up in the brass sleeve. Rotation transfers from the sleeve to the bolt; however, only now with the entire bolt and nut assembly fixed, it turns on the opening in the a-arm. The a-arm opening is not designed to take the rotation and the hole enlarges rapidly, causing the wheel assembly to move in all directions. Have a friend bounce the car while observing the bolt. It should move up and down with the wheel assembly, but should not rotate. If turning, the bolt is frozen and needs rebuilding. Often, enlargement of the hole causes movement of the wheel assembly, and will wear almost completely through the bottom of the a-arm, and when it does, the car drops onto the road, not something you want to happen while moving. There is grease fitting on the bottom of the wheel assembly for getting grease between this bolt and the sleeve. Plus if the bolt moves horizontally when the wheel is pulled or pushed at the six o'clock position, it is warn and needs reworking.

The second weak link on this lower anchorage is where the a-arms attach inboard to the main cross member. Here there are two large rubber bushings that go between each a-arm and the bracket on the main cross member. These bushings are made of rather soft rubber to improve the car's ride, but they erode quickly causing the entire spring and spring pan assembly to move around on the bolts. This movement then transmits to the wheel assembly causing movement.

If there is movement here, the only solution is to remove the a-arms, the spring and spring pan, and the fulcrum bolt and replace everything. First, remove the spring and pan assembly, being careful that the spring does not fly out. Then unbolt the a-arms. The fulcrum pin may have to be driven out with a hammer if it has seized up. The a-arms can be reused if the hole in the outboard end is not enlarged. The brass bushing inside the wheel assembly probably needs replacing along with the fulcrum bolt. This requires a press to install a new sleeve which may involve taking the entire wheel assembly to a shop. Not too difficult if it has been freed from the car at both the top and bottom.

And while the a-arms are disassembled, it is easy to replace the bushings on the inboard end with better material, either the MG V8 bushings or newer polyurethane material. This a-arm removal process is extensive and when reassembled, use the best material possible so it will not need redoing for a long period. Once rebuilt at the top and bottom with new bushings and rubber, there should be no further movement.

Kingpin - One last check on the wheel suspension system is the kingpin itself. The king pin is the large vertical shaft that runs down through the wheel assembly and allows the wheel to pivot when the steering wheel is turned. It has a ring at the top which anchors to the shock absorber arm and a hole at the bottom for the fulcrum pivot to secure this end. This is a pretty durable system on MGs, provided some sort of grease lubrication was done on the car over the years and usually does not wear excessively (no rubber components). There are grease fittings on this shaft (later MGBs had a second one added in the midpoint also) and as long as grease was added at some time, it probably stayed in there keeping this from wearing. If not, you will see movement between the top of the shaft and the wheel assembly at the shock absorber arm connection. This indicates there is wear inside this shaft, either to the shaft or the brass sleeves inside the tube in which it rides. This system can be removed and overhauled with new bushings, new king pins and special reamers tools to insure perfect alignment and fit, but I have found that if this area needs rebuilding, it is easier to just replace the entire system. This is more expensive, but guarantees that the pieces will mate together exactly and that all the bushings are pressed perfectly in place. Again, this system is pretty well built on MGs and lasts, even when little lubrication was done. So check the anchorage at the top and bottom first before proceeding with king pin work. You may not need it once the top and bottom have been refurbished properly.

So the key is to check the wheel assembly for movement in the vertical position to see what is warn and needs work. Checking in this vertical direction only eliminates any movement which could be caused by the steering system which is a whole another subject. And once this vertical rebuilding has been accomplished so that there is no movement here, you can then move on to the steering system if it is necessary, knowing that the suspension system is now not preventing proper steering and handling of the car.

One last note is the importance of doing the proper lube job on the front suspension. Changing the oil is always emphasized as being crucial maintenance and the lubrication portion of this step is merely thrown in as an afterthought. It is just as vital to maintaining a good operating car and vital to keeping the front suspension in tip top shape. So, if you change your own oil in your MG, get a grease gun too and hit those fittings every time. And if you have your mechanic change the oil, be sure to remind him the old car has lots of grease fittings in the front suspension and each and every one needs attention as well.

 

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