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MG MGB Technical - excessive tire war - positive camber ?

You guys have never failed me yet - so here we go again.
1979 B Roadster - problem is EXCESSIVE wear on outer edges of (formerly new) front tires :(
Vehicle has had all new suspension bushes on front end; also replaced the lower control arms with new ones sourced from UK. Tie rod ends also replaced at same time, counting turns on removal/installation to get alignment close as possible.
Vehicle darts in a demented fashion whenever one front wheel encounters an obstacle or loses traction due to sand, etc on roadway. Makes for exciting driving...
Something is hosed - but cannot get to grips with what the problem might be ! Trunions are right way 'round (checked that last night after reviewing archives.)
Judging from tire wear, negative camber does not sound like the problem - wouldn't that cause wear on inside edges of tires ??
Only other thing I have discovered was that the entire crossmember feels "loose", i.e., when nudged while up on jacks, crossmember has fore/aft movement evident.
I think DPO installed lowering kit on rear axle - blocks are visible b/t leaf springs and rear axle.
I saw no evidence of spacer blocks between front crossmember and frame of car.
I wonder if perhaps I was supplied with incorrect lower control arms ? Or if vehicle lowering was done in a half-a**ed way, and some bits are missing ?
Everything went back together fine, no issues in lining up bolts with holes, etc, that would suggest wrong components, etc.
Suggestions ?

Cheers

Chris
C R Craven

Sorry, should have run spellcheck.
Excessive Tire WEAR is the subject.
CRC
C R Craven

Chris

The "crossmember has fore/aft movement evident" sounds very un-good! Find your local MG club and talk with someone who has experience and can look at it with you. If you are in the San Diego area we are meeting tonight. See the web site at http://www.sandiegomgclub.org/ for time and location.

Your local tire store should have a chart on the wall showing the typical wear for different types of alignment problems. A visit and a look at the chart costs you nothing more that a little time and the gas to get to and from.

I would also check the toe in. Check the archives for simple ways to do this yourself. What I do is get a 1x1 and drive a nail through one end to use as a reference marker. Jack up each front wheel and spin it while marking the surface with a sharp nail or similar to get a line all the way around. Do the same with the other wheel. Then use the 1x1 and, from the back side, place it under the car with the nail exactly at the mark on one tire. Mark the rod where the line is on the other tire. Come around to the front side and repeat. Distance between the marks on the front side should be slightly less than the back. 1/2 the difference is the toe in. Check your manual for the specified setting. I run my A between 0 and 1/16".

FWIW

Larry
Lawrence Hallanger

There are four bolts that secure the crossmember to the chassis. These four bolts have four rubber bushings. As do all things made of rubber, these bushings can deteriorate over time. Heaven knows our cars are old enough to suffer from deteriated bushings. When the bushings fall apart, it can allow the bolts to effectively come loose.

If that is the problem, the solution is to replace the bushings.
Paul Noble

How long for the wear to show up?

I'm a simple guy -- have you checked the air pressure in the tires?
glg gimbut

Chris. I had a similar problem with funny handling when I rebuilt the front end on my daughter's car using new kingpins and tie rod ends. Like you, I "counted turns" when removing and replacing the tie rod ends. Took it to a local alignment shop and they found the toe-in off by a full inch. It would seem that some parts are more inter-changable than other parts. Larry's observations seem to be correct by my experience and I would suggest a trip to an alignment shop if you do not want to try the set up yourself.

As to the cross member, tighten the bolts on the upper frame rails and see what happens. Paul is correct that the bushings wear and can wear out. But, the cross member can also develope a little looseness as the rubber takes a set over a period of time. I was taught to check the tightness of the cross member whenever I had the engine out. (Makes the job easier.)

glg. Normally tire pressures would cause either both sides of the tire to wear (under inflated) or the center portion (over inflated). Unequal wear, from side to side, is normally toe-in/toe out or camber. Since camber is set at the factory, the former is the first place to check. Les
Les Bengtson

Les,

I'm just a simple guy who knows just enough to get my self in trouble.

Thanks for the alignment of thought and I tip my toe out to you ! <;+]
glg gimbut

glg. Most of us are "simple guy"s, but, over the years, we learn more and more and wish to pass it on. The value of this BBS is not that anyone "has the answer" but that we can communicate what we know to each other. One of the more significant problems of the internet is that we do not have real time feedback and cannot examine what is happening. Thus, all of us are pre-conditioned by what has happened within our experience and can only apply our experience to what is posted. Often, we tend to "feed off each other". By that I mean, that one person will come up with an idea and others will find that it relates to their personal experience and that they may make a contribution which will expand on someone else's posting. Then, an "idea chain" is born which, as a result of multiple postings, becomes of far greater service than any single individual can provide. The net result is that both the original poster, and those of us who read the threads, learn a great deal. I started posting here about four years ago. It would be the absolute truth to say that I have learned more about automobiles, in the last four years, than in the previous 30+ years of my automotive experience. Many thanks to all of you for this kindness. Les
Les Bengtson

Les,

Hear Here! This is a cyber club. I'm learning more than any ideas I'm offering. Too, it's a wonderful sign that there's a solid crew determined to keep the breed alive.

It is a bit difficult dispensing Rx with out having "the patient" on a workbench before us -- but as you say, the idea chain is a wealth of information.

Too, with so many changes during production, without a year of manufacter, (or at least year of title), well you know it's just a shot in the dark.

God's Speed and Saftey Fast!


glg
glg gimbut

Thanks Guys - good insights here. I appreciate your responses and encouragement.
Wear on tires is severe (i.e, cord showing in places ! Embarrasing to even admit, but it's true.) Occured over 8 months light city driving, so something is definitely amiss. Tire pressures OK, kept at approx 32 PSI. Rostyles, BTW, if that makes any difference.
I will check toe-in tonight as part of "process of elimination".
Does anyone have a photo or can they steer me towards an illustration of RB crossmember ? I cannot grasp where the spacer blocks are located. All I can recall are thin (1/8" thick) rubber pads between crossmember and frame rails. Is that all that should be there ?
If lever arm shocks are cream-crackered, would they also contribute to this sort of wear ? I have to believe these are originals, and they probably reverted to toilet plungers 50k miles ago (116,000 miles on car.)
Cheers
CRC
C R Craven

CRC, you can see where the pads for the crossmember are located in these photos. The second photo shows one bolt with the upper and lower pads on it. These photos are from Mike Zaffrano's web site. Sorry Mike if I misspelled your name. Clifton
http://www.mzaff.com/Images/1977roadBack/xmember/xmem01.jpg
http://www.mzaff.com/Images/1977roadBack/xmember/xmem02.jpg
Clifton Gordon

The other guys are dead right about alignment causing "darty" steering. I had a little car (Singer Chamois) which was almost undriveable because of the weird steering responses. When checked the alignment was way out. Put it right and the car behaved beautifully. On the other hand, if your cross-member moves, it needs fixing!
Mike
Mike Howlett

I learned this past weekend when I finally got around to replacing my steering rack boots. My steering had been spot on prior to doing this. When I got everything back together the steering felt very light and when I went for a test drive the steering wheel wouldn't naturally return to center after making a turn. I got one of the alignment gauges from Moss and found the toe-in was way off. Adjusted that and noticed an immediate improvement.
Greg Smela

This thread was discussed between 01/04/2003 and 02/04/2003

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