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MG MGB Technical - wheel shake between 55-70 mph

My steering wheel shakes alot at highway speed.I checked my shock absorbers, alignment,tyre pressure and wheel balance and they all check out. My Hanes manual says iy might be due to "steering damper". What is a steering damper? Also my steering rack is only 1 1/2 years old.
William

Had the same problem - it was caused by the wheel being out of true or out of round. This can be seen right away when the the wheel is spun quickly as on a tire balance machine. Tire shop guy said wheel weights can fix it but I found that only replacing the wheel is the real remedy.
willieL

I forgot to mention, you can swap the rear wheels to the front. If your lucky, they will be in better condition, and bad shape wheels in the back generally will not show as a shaking condition. Then you can take your time in looking for other wheels. I have found that it's not easy to find good used Rostyles.
willieL.

A bad Universal joint will cause this. Grip the drive shaft and see if it wiggles. U-joints are cheap and easy to change --- if the shaft drops and catches on something it is $$$$$!



Dan Robinson

Also, an out-of-round tire can cause this problem. A good alignment shop ought to be able to find it. Switching wheels front and rear as Willie says, can be very illuminating!

I bought Performance (Ossie) minilite replicas. Great price, problems gone. Old Rostyles can be a pain in the behind. Even ones that look terrific can be bent - and darned if I can tell by examining them.

FWIW,
Allen
Allen Bachelder

I have no affiliation with Hendrix Wire Wheel out of Greensboro N.C. but I found this flyer of theirs interesting, it states: Does your MGB vibrate at 55mph? We know why and more important we can make it go away. Rostyle wheels were never meant to be balanced by the center hole. It is not a true center. We have the correct factory adaptors for balancing by the bolt pattern as was done by the dealerships. This gives you the perfect balance you deserve. We will shave true your tire and get a perfect balance on your wheels giving you the smooth ride you dream of. Can be reached at www.hendrixwirewheel.com or 336-852-8909
Mwhitt

William. The term "steering damper" is either a form of shock absorber attached, horizonatally to the steering system, or the shock absorber. In our case, the term refers to the shock absorber, hydraulic dampener, which forms the upper "A" arm of the suspension. I had the left hydraulic dampener go bad a number of years ago. On the highway, the left front side of the car was moving up and downwards in such an erratic manner that passing drivers would pull along side and shout out that there was a problem. Thus, a bad shock might be observed by another car who would pull along side you and have the passanger observe what is happening with your car.

The others have provided good advice. Willie is quite correct that with an out of balance or out of round condition on the front, changing the wheels to the rear axle, on the same side, will transfer the problem to the rear axle and make the front work fine. If this happens, assume an out of balance tire, an out of round tire or an out of round wheel. (This latter very common with wire wheels and sometimes seen with older Rostyle wheels.)

If the wheels are swapped front to rear and the problem remains, it indicates a problem in the front suspension, perhaps your "steering damper". One thing seldom checked is the U joint on the steering column. I have had only one go out in my lifetime. But, when it did I had a difficult time diagnosing the problem. Checked the tire pressure, tire balance, tires out of round, wheels out of round, shocks, kingpins, etc, et al. Finally checked the U joint on the steering column. It checked bad (slop). Replace it and the problem has not recurred for several years of driving. Probably not your problem, but worth checking because no one ever does.

Les
Les Bengtson

M. Very true and, if someone has Rostyle wheels and seems to have a problem, this is well worth considering. A "knee" type dial indicator on the outer edge of the tire or a standard point on a dial indicator on the outer edge of the wheel should be able to indicate whether the tire is out of round or whether the wheel is out of round and forcing the tire to run out of round.

Whether it is worth shipping the wheels to North Carolina to have them properly balanced is something of a personal decision. But, you are completely correct in your observation that the claims of Hendrix Wire Wheel are true. Rostyles do not seem to have concentric center holes and if balanced on a machine that is using the center hole for its point of reference, problems will be quickly noted.

By the way. Please by so kind as to sign your posts with how ever you might like to be addressed. You have made some excellent suggestions, offered up excellent ideas and have shown yourself to have some excellent ideas. Thus, I feel, to me at least, that some form of name or honorific should be applied in addressing you. Should I prove mistaken in this, will "hey, you" suffice?

Les
Les Bengtson

I have been working on these cars since 1965, and I have NEVER seen a bent Rostyle wheel that did not have obvious and significant rim damage, but I have had a lot of customers bring cars in with "bent" wheels. Typical was a couple of years ago when after 4 or 5 balancings to get a 55-65 mph shake out, my customer came in and said "all 5 wheels are bent as much as 3/4", and the tire guy showed me on the machine." After much argument, I finally took all tires off the rims and ran a dial indicator on all 5 at the bead seats and NONE were off as much as .030, laterally or radially. I put the tires back on and with the pads retracted balanced them by mounting on a front hub and spinning it by hand. When I was done, there was no more than 1 oz on any wheel, most were 1/2 oz. I had a couple of pounds of weights left over though! No more shakes. This is typical, the Rostyle is one of the stiffest wheels made, and it is virtually impossible to bend them without destroying the rim. But as several people have stated, you CANNOT balance them with cone type locaters on either side - they MUST be mounted on a hub with studs. Most modern tires will balance with no more than 1 oz max. - if you have more than 2 oz the guy doesn't know what he's doing.
As Allen states, a bad tire can also induce shake. This is usually pretty obvious if you spin the wheel and watch the tread as it turns.
There is a friction damper in the rack, but this will NOT "cause" a shake, though it may allow any shake that otherwise exists to be more obvious.
FRM
FR Millmore

I recently had this problem too (steering vibrations at 60mph). It came on suddenly while driving down the motorway, which led me to believe a wheel weight had come loose, so I took the car to the local generic tyre shop said the weel rims (rostyles) were bent. Now this could have been to the inadequate methods they use as outlined above.

So I took them to a proper rim reconditioner, who confirmed they were out - he was one of the those 'old timers' who I got the impression knows his stuff - Like Les Bengtson's brake drum tuner.

Anyway, I had them fixed & balanced...one was still, he described, as 'oval'. Steering vibrations gone (although my front end shocks are tired as well).

Old timer says rostyles are faily notorious for being non-true due to the manufacturing process, and some guys try many rims until they get a fully true set.

Given the timing of the onset of my problem, I still suspect I'd lost a wheel weight, but at least I now know the state of play with my rostyles. After all this, I'm looking at some minilites at some stage anyway.

Off topic: my sister's BGT has some of those lovely, rare chrome rostyles...no changing those out for anything else!
Curtis Walker

Les, thanks for the kudos. It is just easy to type Mwhitt is all.

I have been into MGB's since around 1970 and have owned all year models except a 62 and 63 including numerous C's.

Since I have discovered this site the people here have expansive knowledge and I like to add my two cents worth too.

My wife runs a set of Minilites on here 80 B currently and has no problem with the centering on the local balance machine and I am running Minators on my 63 Sprite with no problems either.


Safety Fast!
Mark Whitt
Mwhitt

Mark - that's exactly right - minilites should not have the same problems on a balancer as rostyles, mostly because the manufacturing process of alloys is entirely different to that of rostyles which sound like they're literally beaten out of the steel, rather than precisioned machined like minilite-style wheels.
Curtis Walker

William originally asked about the "steering damper" being a contributing cause of his shimmy problem.

At the "T" junction of the lower steering assembly, there is a removable plate. Inside is a spring loaded brass cylindrical pad which Moss call the "damper pad" and Vitoria British calls the "pad-rack damper." This pad - about 1/2 inch in diameter - can indeed be worn and will contribute to front end shimmy. I replaced mine and it helped considerably. The part costs $13 to $17 depending where you source it.

My replacement was kind of tight fitting. But with some emery paper and crocus cloth, I got it to fit very nicely. When you put everything back, fill the cavity with heavy gear oil (this according to a tip from Moss) before putting the top plate back in place.

Tom Fisher
T.R. Fisher

Once more, Fletcher Millmore has spoken, and once more, I have learned something. It always happens. No wonder I couldn't see where my Rostyles were bent; they WEREN'T. They were balanced on one of those cone receivers on the balancing machine. If one of us cut off an old rear half, leaving the four-bolt hub with perhaps 6-10" of shaft, could that be chucked on the balancing machines in place of the cone? I haven't ever looked carefully at one of those things, so I don't know.

FWIW,
Allen
Allen Bachelder

My car had vibrating front wheels for 2 years. During this time I fitted replacemt stub axle assys, new wheel bearings new wire wheels , and then swapped one of the back that was better than the new one and finally new discs. Now it's fine but all the above needed to be in good order. I also adjusted the shims in the steering rack.
Stan Best

Since the Rostyle are not hub-centric..I found balancing them using a 'finger' attachment to mount the rims to the balance machine works quite well. I always check the runout on the wheel with the balance machine..of course the machine routinely comes back with fail or marginal..You can actually see the flaws if you look for them when you spin the wheel.

When I mounted my last set of tires..I couldn't get one to balance to save my life (the wheel 'failed') but kept at it..did a match balance..and I got it to be acceptable..still some steering wheel vibration..but the true solution is to replace the wheel.

In the past when I brought the Ros to a tire shop, they would not balance well..no matter how much they tried (they were mounting it in the center of the wheel) But now that I do them myself (at school) the results have been a lot better. The right tool makes the job.

I would try and find a shop that has a 'finger' balance attachment..if they look at you strange..go to another shop.

The only solution in my case is to replace the 2 offending wheels with new ROs. Or just get a new set of minilite replicas or Ultralites or something.

Paul
Paul S

Regarding Paul's comments:
I have no idea what a "finger attachment" is, but I suspect it's another half-assed way to do the job, albeit possibly better than the cone approach. The main point here is that there are two critical areas on any wheel - the hub mounting face/stud holes (or the two tapers on a wire wheel) and the tire bead seat. ANY other surface is likely uncontrolled, unless it is a machined wheel. You can't see the bead seat with a tire mounted, so unless the mounting method is absolutely accurate AND repeatable, you will never know if the wheel is mounted correctly on the machine, and if it is not, then you cannot correctly balance it. In particular, the rim outer flange is NOT a controlled surface, either radially or laterally. To really see if a wheel is true, you must have the tire off, and mounted on a hub with correct nuts. IF the machine adaptors are correct, you should be able to mark the alleged "out-of-true" points on the wheel and have it read exactly the same no matter how many times you remove and replace it on the machine, and no matter how many positions you put it in. There will normally be a small area of the bead seat that shows some increased deviation near the weld in the rim, but this will be very local and will not cause trouble. I will repeat that I have not seen any bent Rostyles that were not obviously damaged, and I have checked a lot of them that were certified "bent" by tire shops and customers.
Speed specific shakes are virtually always caused by out-of-balance conditions, usually resulting from poor balance jobs due to bad location on the machine. Occasionally a bent wheel can cause a shake that will resonate with suspension frequencies, but there is always an underlying vibration which increases directly with speed in this case.
FRM
FR Millmore

FWIW, a 'finger' attachment is the adapter that fits onto the balancing machine and replaces the cones with a hub with mounting bolts. The one I have seen used had the mounting bolts (fingers) on a mechanism to move in or out - to cope with different diameters of mounting holes on the wheel.

Most shops will charge extra for using them, if they have one, because of the extra time and hassle involved.

Richard
Richard

Yes it is an attachment that locates the wheel on the machine via the lug holes. It does a wonderful job. Most shops will charge extra, if they even offer the service. It is pretty cool. It certainly balanced the ROs better than using the machine alone.
Paul S

"Most shops will charge extra for using them"

Not at Just Tyres in Solihull. I always have them used on my V8 wheels, takes them hardly any extra time to fit as opposed to the cones, and no mention of an extra charge. Whilst they did give a better result than using the centre holes (which should *never* be used on original MGB wheels as the centre hole was never intended for balancing and just isn't concentric enough) there is still slight shimmy, most noticeable on motorways. Here the shimmy varies according to whether I am going round a gradual left-hand or right-hand curve as opposed to a straight - one way the shimmy fades in and out faster than on the straight, the other way slower. Seems to be a circumferential difference as well as balance, and this is with multiple sets of tyres, some worse than others.
Paul Hunt 2

I had persistent shimmy on my 66 GT One day after a trip I was determined to "cure" it when I got back to my workshop. I have 5.5 72 spoke wheels balanced on a spline fitted to my wheel balancer. I checked the front wheels again - seemed perfect. When spun on the car the LH wheel had a slight wobble so I changed it for the rear one. It too showed a slight wobble so I checked them both again on the balancer - both were witin about .5mm. I then checked the LF hub with a dial gauge and found the inner taper to be a bit out so I set up a die grinder & ground it true. This improved the wobble. I then swapped the knock-on for the rear one. Hey presto the wheel now ran true - but the rear wheel then had a wobble. THE KNOCK-ON WASN'T MACHINED TRUE. A new one now gives me a smooth ride. Incidentally I have always used an adaptor so I could bolt on Rostyle wheels.
Garth.
Garth Bagnall

This thread was discussed between 27/04/2006 and 12/05/2006

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