MG-Cars.info

Welcome to our Site for MG, Triumph and Austin-Healey Car Information.

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGA - Significant Body Vibration 4th gear only

I've been through the archives re:vibrations and have not found a similar issue ...

I have a 60 MGA 1600 with a significant body vibration steering wheel et all that consistently occurs in 4th gear at 3200 rpm through 3400 rpm.

Lower than 3200 and higher than 3400 the car is absolutely smooth.

I've gone from 0 to 4000 rpm in 1st,2nd,3rd gears and neutral and the car is smooth as silk.

I've had this problem many years since I first got the car. Generally, avoided cruising in this range, put it on my to do list. Time is way overdue to address this.

I have a Petronix Ignitor Positive Ground, LU149P12 in a DM2 distributor. I installed the Ignitor in 2019. Timing is set at 7 degrees BTDC. Vibration preceded this.

Also, I have a Salsbury axle with a 3.9 diff, came installed.

Lastly, I have disk steel wheels.

Any help will be most appreciated!!!

Paul



Paul Hinchcliffe

Get the wheels re-balanced - the centre hole should not be used to centre the wheels on the machine.

Dominic Clancy

Paul - you talk about engine rpm, but such vibrations are tied to speed (mph) if the wheels are the cause.

Given the mph you experience the vibration in 4th, does it disappear at the same mph in 3rd?
KR Doris

Depends on the frequency of the vibration
If it's a buzzy type then it's probably tailshaft related
but if it's a more hoppy/bumpy vibration ,then maybe wheel balance
To be in such a small rpm window I'm leaning towards tailshaft balance or a failing u joint
maybe first step would be to get the wheels (4) balanced and check the u joints for movement/wear
William Revit

If tailshaft vibration is suspected the first action stated in factory documentation is to disconnect the rear tailshaft flange and rotate the shaft 180 degrees.
While doing this check that the joints of the front and rear joints are in the same plane. This is shown in the Workshop Manual. This problem is caused by not fitting the tail shaft splines correctly.

Mick
M F Anderson

Thanks all for sharing your knowledge, and providing me with areas to investigate.

As I follow upon your leads, I will update you.

TO KR - mph vibration window in 4th is 60-62mph.

As to pushing same 60-62mph in 3rd gear...I'm 72 with Parkinsons (and yes, I'm sure the vibrations are the car not me...we all need to lighten up and be able to laugh at ourselves :) I really am) well in 3rd gear, trying to reach 60-62mph can give you white knuckles...but I did, so 3rd gear pushing to 5000 rpm hit 60-65 mph area. Vibrations started as I was passing thru 55mph and continued on up. Lost nerve to push beyond 5000 rpm to see if it smoothed out above 65mph.

Does that tell us anything ... about the car, not me.

I will proceed with the other work.

Thanks all,

Paul
Paul Hinchcliffe

Paul,

If checking the tailshaft remember to check the universal joints.
There should be NO free play in U-Joints.

Mick
M F Anderson

That indicates that the issue is rpm rather than mph related, which points to driveshaft UJs as the others have said
Dominic Clancy

That speed is a real wheel balance problem area
Could be either end so I'd get the 4 done and as Domenic mentioned earlier they are lug centric so need to be balanced from the boltholes ,not the centre hole
Could also be a dud shockabsorber letting a wheel go bonkers without damping

Also could be tailshaft but I'd be getting the wheels done first
William Revit

I've been tempted to suggest this before, as it's free and relatively easy to do, try swapping front wheel or wheels to rear to see if the vibration changes.

I'm also thinking of tyres, they can wear unevenly, or if the tyres are hard from age and/or lack of use.

Moving them will give the opportunity of a good visual check to the wheels, tyres and fixing to axle.
Nigel Atkins

Dominic - you say it is rpm related, yet I take Paul's 3rd gear experiment to show it is mph related, thus your original suggestion about tires (tires?) is the most likely culprit.

Also, Nigel's suggestion about swapping tires is a great simple way to see if things change without going through a full rebalance.

- Ken
KR Doris

I am a bit puzzled by the emphasis on wheel balance.
If we go back to the original message posting the vibration is described as occurring on reaching a certain speed and then ceases at a higher speed.
If a wheel is out of balance it just gets continually worse with increasing speed as does any rotating item.

Mick
M F Anderson

Good point, in isolation that'd be so, but the reason for the imbalance, or other faults in that area, in real world events could mean the vibration is most noticeable at certain speed or rpm and possibly less noticeable or intense before and after lost in the cacophony of other things going on with the car. Sometimes (often with our cars?) it's not a single issue but a combination or permutation of issues that can be less, or more, intense or noticeable either by themselves or together. The cars are old and components worn and whilst often within acceptable parameters of use and performance sometimes parts can stray outside of these parameters.

At least a look-see with the wheels off is easy and cheap and a good service and maintenance practice and if it doesn't help with this issue it might find or prevent other issues and if not at least gives peace of mind over those areas for a period of time.


Nigel Atkins

I take your points. Balancing wheels is always a cheap and good first step to address vibration issues. Which is why that was my first reaction. Balance weights don't always stay in place, nor are all balances correctly done (I had 270g removed from a wheel two weeks ago after problems - only 40 g went back on!)

But the speed Paul reached to get vibration in 3rd gear corresponds in RPM to the same vibration RPM in 4th. He is experiencing the vibration at a lower speed, but the same RPM, so I deduce that the issue is RPM correlated not MPH / KPH correlated. For me that would indicate prop shaft issues..... but I could of course be jumping to wrong conclusions..............
Dominic Clancy

Paul
Did it vibrate at the 3200-3400 in 3rd gear
William Revit

Paul:

Rotate the tires. You have nothing to lose. If the tires are radials, inspect each tire as you rotate them to look for any signs of belt separation, ie: bulges on the tread,or sidewall.
If all is well then find a garage that can balance the wheels while still mounted on the car.

My 79 MGB had a vibration which turn out ot be the front U-joint. Check that too.

Cheers

Gary
79 MGB



Gary Hansen

Dominic,
I agree with Ken. When Paul tried to duplicate the vibration in 3rd gear, he had to push the engine rpms to 5000 to get to 60-65 mph where he said it vibrated. He indicated that in 4th gear, the vibration occurs at between 3200 to 3400 rpms at about 60-62 mph. This means the vibration happens at about the same mph regardless of the rpms.

Jim
JL Cheatham

Hi Jim

Not quite.... Paul doesn't help by making contradictory statements which I list below as quotes from his messages:

1. I've gone from 0 to 4000 rpm in 1st,2nd,3rd gears and neutral and the car is smooth as silk.

but then

2. Vibrations started as I was passing thru 55mph in 3rd

3. vibration consistently occurs in 4th gear at 3200 rpm through 3400 rpm

4. vibration window in 4th is 60-62mph.

Logically at least one of the above statements must be inaccurate

If the vibration starts at a lower speed in 3rd than in 4th and is described as a buzzing rather than a wheel shake, my conclusion is that it must be RPM related not MPH related.

But I am sure (like most) that if Paul has the wheels rebalanced as a first step, he will be one step closer to identifying and resolving the problem

Dominic


Dominic Clancy

Previously I was going to post that the dials in the car could be as shaky as Paul himself - but thought it might upset some viewers as they may think it's OK for Paul to joke about his condition but not others.

I also wasn't sure if the numbers tied up with the gearing of the car.

But it's difficult sometimes/often to keep a close eye on things whilst driving on the road and I'd be the last to comment on absolute clarity of, particularly written, explanation, as has been witnessed many times on the BBS.
Nigel Atkins

Paul,
I've no idea what road conditions and traffic are like in your area but it could be often very difficult where I am so a suggestion which might be wayyyy of the mark.

A rolling road can hold a car at fixed revs through the range for as long as the petrol lasts, without the worry of changing road conditions and traffic. Also at the same time take full advantage of you electronic ignitor by find best performance (which many forgets includes economy) for your timing, spark plugs gap and carbs mixture. Then your car will be even smother and perhaps higher revs less intimidating.

Where I am balancing the wheels on the car is very much a thing of the past, I'm sure there might be places that do it but I've not heard of them. Mind you the state of our roads you'd need to go in for rebalance regularly. I rely on a series of potholes knocking the wheels in various ways so by the end the wheels are back to where they were ready for the next series of potholes to do the same.
Nigel Atkins

Hi all,

allow me to respond. I do have a friend who helps me with some of the work, and will assist in rotating wheels, but I'm dependent on his availability, so my followup actions are not often immediate, although I wish they were. and I will report back.

I will be rotating wheels and report back.
I have been in contact with several garages to do lug-centric balancing, or on car balancing ... no luck yet.

Nigel, I initiated the light heartedness because I knew that my physical tasking could not be immediate and I needed to explain why - having said that I'm good with lighthearted throw back.

Road condition for testing, I took my car out on a divided interstate highway, ...smooth road pavement.

Dominic, I'm unaware of any contradictions but may have ...your 4 points with my comments in parenthesis. here goes:

1. I've gone from 0 to 4000 rpm in 1st,2nd,3rd gears and neutral and the car is smooth as silk. (not 4th & not above 4000 rpm)


2. Vibrations started as I was passing thru 55mph in 3rd ( yes, in 3rd but above 4000, I believe about 4500 )

3. vibration consistently occurs in 4th gear at 3200 rpm through 3400 rpm (in 4th)

4. vibration window in 4th is 60-62mph (in 4th at 3200-3400 rpm as stated above in #3).

I don't see any contradiction.

Paul


Paul Hinchcliffe

Why note put a couple of good quality axle stands under the rear axle and run it up to the rpm where the vibration occurs in both 3 rd and 4th gear with wheels on and wheels off? Be careful! My thoughts are that it maybe prop shaft balance issue.
Mike
Mike Ellsmore

Hi Paul,
thank you for your reply to my comment.

By road conditions I was thinking of twists and turns but also if there's lots of traffic to be aware then less concentration on (possibly unsteady) gauge needles - but you seem pretty certain of your readings. :)

Let us know how you get on when you can, you could find something that some of us don't know or have forgotten about - or virtual cigars are offered out for correct suggestions, I've no idea what they taste like though.
Nigel Atkins

Perhaps the simplest way to determine rpm vs. mph is to take the car up in 4th to above the vibration window (say 65?), then shift into neutral and let it slow down through the 60-62 mph window and see if vibration occurs.

If it does, then mph, if not, rpm.
KR Doris

The wheels and tailshaft will still be spinning

Mike's idea of running it up with it on axle stands is the go , wheels off, if the vibration is still there it's tailshaft related if it's gone it's wheel balance

I'd love to have a drive, there is a significant difference in frequency between tailshaft and wheel balance vibrations
tailshaft buzzy wheels more shakey
William Revit

Well, I'm back with significant progress.

But first, some additional information.

Dominic mentioned weights on the wheels, so I checked mine, which were:

Left front 113g
left rear 21g
right front 71g
right rear 21g

my tires are kumho power star 758 tires 165/80r15

Also Dominic mentioned balancing...still looking for lug centric balancing.

I rotated wheels:
LF -> RR
RF -> LR
LR -> LF
RR -> RF
seem to recall wheels with greatest added weights should be in rear.

And U-joints had slight play, greased drive shaft ends at u-joints.

Took my A out on highway (to the lads from down under, putting on jack stands at 60mph ... I'm not ready for yet, but thanks for your help) and so I went on to the highway from 0 to 70 with zero vibes.

Looking to get all wheels balanced and new u-joints replaced.

Thanks everyone, you were all a great help!

Paul
Paul Hinchcliffe

20 years or so ago I had similar symptoms with my then disc wheel car. I had them balanced while still on the car. Sorted the issue perfectly. However, a year or 2 later I was unable to find a garage that still had the on-car balancing kit. Are they still around anywhere? Not that it matters to me now as I changed to WW and have a set of cones for the tyre shops to use on their machines.

Steve
Steve Gyles

Paul,
well done.

Tyres are a bit of a hobby horse to me on classics, often the tyres have plenty of tread but are hard from age and/or lack of use so don't perform as well as they should even with maiden-aunt driving styles.

Tyres are a complex component that affect braking, steering, handling, roadholding and ride comfort and noise.

Having a tyre that wears very well on a low mileage classic actually isn't the best idea, better to pay more and get a tyre that wears more but gives better grip and handling (and braking).

Unless the tyres are recent I'd look at their age (and condition of tread and sidewalls both sides) and considered changing them which will get the wheels balanced as well.

The production age of the tyre is in a four digit code on the sidewall (three digits is before the year 2000, 20 years ago). - https://www.tirebuyer.com/education/how-to-determine-the-age-of-your-tires

Tyre pressures are relevant too.

This'll cause controversy - depending on your wheel size you could also consider, if available, 155/80r15 tyres - https://www.vintagetyres.com/tools/

I assume greasing the UJs is part of the regular servicing on the car but being on the underside it might get missed sometimes.

I'm just trying to take you from good to better. :)
Nigel Atkins

Steve,
I've not heard of any around where I live for very many years but then I've just remembered, but I could be on fantasy island with this, there might be mobile tyre fitters that had the facility(?), a few years back perhaps(?), the more I type the more I doubt myself.
Nigel Atkins

Nigel

Seems they are still made. Quick search brought up this one for anyone who does not know what I was referring to.

Steve

Steve Gyles

Paul - congratulations on the solution!

You may not remember but Melon and I met you a couple of times when we joined the Cape Cod British Car Club (CCBCC) back in 2006. Great club and really enjoyed the events, but living on Long Island, made the trek across the Sound to meetings too much to continue

At that time we had the same Kumho tires on our A, but finally replaced them in 2017 with Vredsteins (the Kumhos are no longer available) after realizing that while they still had plenty of tread after 40K miles, they were as hard as plastic.

I agree with Nigel - please check your tires' age and replace if older than 5 - 7 years.

Cheers,

- Ken
KR Doris

Good stuff Paul
I was waiting to see how you went racing on the jackstands though--it would have told you if it was t/shaft or wheels straight away

we used to have a spin up on the car balancer, best thing on the planet for finding wheel bearing noises, you can still buy them new

You need to find someone with a fitting on their balancer like this---that locates on the studholes

https://bobistheoilguy.com/forums/attachments/usergals/2018/01/full-57046-18907-img_2951.jpg
William Revit

The on-the-car balance machines are still made then, thanks Steve, but like that exotic bit of kit Willy put up I'm not sure where you'd find them locally, in the UK, perhaps with Willy and in USA but rarer here I'd guess.

Unless a marque dealer or very specialist place you'd be lucky to find even in a tyre place that deals with expensive sports cars they doesn't use a rattle gun and torque wrench permanently set to 120nm let alone those machines - even if you tell them that the wheel nuts on a Spridget only want 60nm (45lb) otherwise a stud might be pulled.
Nigel Atkins

Unreal Nigel
That's a fairly std .fitting for wheel balancers here ,I'd say 90% of tyre services would have them
but then again most cars now have their wheels centered on the hub not the studs so cones are used mostly --a lot of 4wd vehicles have a large centre hole and rely on the 6 studs to centre up , you need the stud centric plate adapters for them for sure

The spinup on the car balancers have died off a bit because of front wheel drives and load sensing lsd's etc making them a bit useless , but for our 'normal' cars they're worth their weight in gold
William Revit

Perhaps I'm wrong Willy but I can't remember seeing them or being offered them.

I'm sure as an engineer/mechanical type if you came over here you could find not just tyre related but all the facilities you're used to and persuade the people to have access to them but not an ordinary car owner like me.

Next time I see my mate I'll asked him if he knows of stud-hole balancers as his mate owns a 'tyre shop'.
Nigel Atkins

Ken, great to hear from you - I must admit my tires are old (12 yrs) 5008 - i am getting new tires & as Dominic suggested early on will lug centric balance then.

Nigel, spot on tires .... taking your advice.

Thank you all,
Paul
Paul Hinchcliffe

Paul,
once you've run-in your new tyres I'm sure you'll notice the improves they give, of course you'll soon get used to that improvement and forget about it and use the car to the standard the tyre change gives.

In case the tyre places doesn't remind you - allow the tyres about 100 miles, 200 miles in the wet, to get the 'grease' off them before harder braking or handling. And check the wheel nut torque after 30-50 miles.

Even if it makes no improvement to your vibration issue you will have gained worthwhile (and safety perhaps) improvements.

Nigel Atkins

Willy,
I emailed my mate, he doesn't know of anywhere (local?) that has stud hole balancing.
Nigel Atkins

I had an MGB GT on Rostyles.

I got two new tyres on the front.

I found that there was bad vibration at 70 mph.

I swapped the wheels over, L to R. Vibration gone.

The garage man didn't believe it, but it happened!
Geoff Everitt

Decades back it was a garage man that suggested I try swapping the wheels as it was often tyre wear that caused the problem. I think most modern tyres wear more evenly today.
Nigel Atkins

Nigel
National Tyres Northampton have finger plates for 4wd's don't know if they have a four stud one for the 4 x 4" bolt pattern---usually the plates have masses of holes and you move the studs around to suit the bolt pattern--just depends what they have
Some even have adjustable fingers to suit any stud pattern

https://www.google.com/search?q=wheel+balancer+finger+plate+4+pin&tbm=isch&ved=2ahUKEwjG6trCivTrAhWE5DgGHYS7AdwQ2-cCegQIABAA&oq=wheel+balancer+finger+plate+4+pin&gs_lcp=CgNpbWcQDFDhmwdYvLwHYLXPB2gAcAB4AIABmwKIAYgKkgEFMC4xLjWYAQCgAQGqAQtnd3Mtd2l6LWltZ8ABAQ&sclient=img&ei=zWBlX4bQGoTJ4-EPhPeG4A0&bih=554&biw=1252&client=firefox-b-d
William Revit

Willy,
never trust a computer, they don't have finger plates, I've just rang them (01604 750 327), a very helpful chap called Dan said he thought a customer had told him another local place might so I'll ring them too another time.

Dan laughed when I asked about the sit on machines and said he'd not seen them for many years.
Nigel Atkins

Interesting-
The only reason i named them was that i'd been on a 4WD forum and a girl on there had had trouble with wheel balance and had her wheels balanced there and she said they used the lug plate to do it and it fixed her issue---bit weird
William Revit

Perhaps she had it done at the other place that Dan's customer mentioned, he thought it was Scots Tyres, a place I've known of for decades and my neighbour took me to last year as he uses them, they'd moved location by then and the new place certainly didn't strike me as a place to do much out of the ordinary, but perhaps they specialise in 4X4s for some reason. I'll ring Monday afternoon or Tuesday to see.
Nigel Atkins

Nigel
Superior Cars. 4 Horseshoe St, Northampton have a plate with 4x4"(Midget) bolt pattern for their balancer and want 10 pounds per wheel to balance them
willy
William Revit

Willy,
I've just rang Superior Cars, again another very helpful chap, he has an adjustable frame(?) but he said he's found it doesn't adjust to all requirements but they happily give a wheel ago to see.

He also said balancing on car (with cart) he'd not seen for many years.

Their website shows they're family run and been in Northampton 27 years, I remember the sign going up but surely that was only a few years ago not 27, the blink of an eye.
Nigel Atkins

Ahh ,very good
I suppose it will depend on the diameter of their plate and the length of the fingers for clearance of the plate against the spokes of your wheels and how deep the stud holes are into the wheel
The fingers are usually about 2" long
There are 2 different types ,one is adjustable having the fingers on adjustable cams which sounds like what he's got --the other is a multi hole plate with several stud patterns and you just poke the fingers into the required holes,
If it's one of the latter and it's real close but won't quite clear the spokes of the wheel, the dicky bit of the finger where it plugs into the plate is usually fairly long and I've fitted a couple of flat washers under the fingers in the past to get a fit
but your wheels are reasonably flat on the outside compared to some, I reckon you'll be ok
William Revit

Thanks Willy, but it's not for my wheels just a general enquiry for anyone, particularly that is nearby.

My wheels are alloy Minilite copies and just get the standard use and abuse, no special treatment.
Nigel Atkins

Well, yesterday I had new 165R15 tires mounted and wheels balanced:

- left front no weights
- left rear 3.0 oz
- right front 1.25 oz
- right rear 2.0 oz

As I started out in 1st, had a thump, thump, thump. In 2nd, more frequent and pronounced, 3rd more pronounced, 4th vibrating worse than previously reported.at all speeds.

Placing on lift this a.m. to check tail shaft and u-joints as previously recommended above.

will report back soon.

Paul
Paul Hinchcliffe

Thump thump thump at low speed like that sounds more like a tyre with a flatspot or dare I say it a loose wheel
William Revit

Bit of a betting man, if it was a loose wheel my money is on the RH side------
William Revit

My experience of the "tire shops" here is that generally for our cars they overtighten the wheel nuts and on many vehicles over inflate the tyres.

Paul,
in case the tyre place didn't remind you - allow the tyres about 100 miles, 200 miles in the wet, to get the 'grease' off them before harder braking or handling. And check the wheel nut torque after 30-50 miles - but you'll probably have already checked the wheel nut torque by now but repeat this in 30-50m.

Be interest to find if this is a new problem or whether problem(s) now possibly resolved on the wheels and/or tyres were partially masking the sound and/or effects of the main problem.

Did that make sense, I mean that a mix of sounds and problems can combine to make it difficult to locate, or hearing, them individually
Nigel Atkins

Hi all,

In the days following the new tires, the vibrations smoothed out without extra efforts.

Tail shaft and u-joints checked out fine.

The year code on the tires is 2920, that is the 29th week of 2020, or Jul 13-19, 2020). Is it possible that the tires were stored for a few months in such a way that a distortion took place which worked out once driven several times?

Thank you all for your help, it was very beneficial!

Paul
Paul Hinchcliffe

More likely that driving the car more (frequently?) has helped the car generally, all components getting more movement.

July manufacture isn't that long ago, if stored correctly they can be stored for much longer.

Keep driving the car regularly and frequently on reasonable length journeys and things could evenget better.
Nigel Atkins

That's interesting Paul
Can I ask what brand/type/model tyres you bought
William Revit

Tyre shelf life - https://www.tyresonthedrive.com/blog/tyre-shelf-life-how-long-do-tyres-last
Nigel Atkins

Sorry, should have provided brand/type/model tyres:

Firestone F-560 Radial Tubeless
165R15 86S

Tire pressure
30 lbs front
32 lbs rear

Any other information that I can provide, please don't hesitate to ask!

Thanks,

Paul
Paul Hinchcliffe

Thanks Paul
They're supposed to be a good tyre, so yeah ,one or more must have been squashed up out of shape or something to start with
A nice long run will/should get them going
Interesting the 30/32 pressures
28f/26r (cold)usually works well for an mga on the road and up to 30 in the rear when loaded
--might be worth a try, dropping them down for a try
MGAs are nearly 50/50 weight distribution with 2 on board so don't really need high pressures in the rear unless it's loaded up
willy
William Revit

I had exactly this wire wheel balance problem you are getting here, its all to do with hitting the right speed that matches the resonant frequency of your suspension - mine was worse at 55mph. It took me 8 years of misery to realise modern balancing machines cannot run the wheel true to give an accurate balance. They grip the wheel between two cones, the outer incorrectly gripping the rough inside of the wire wheel instead of its accurate outer cone that the spinner tightens on.
You will see the wheel running out of true in the machine which is not how it runs on the car.
From an old worn hub and spinner I machined up an adaptor which allows the machine's outer cone to locate in the hole machined into the spinner. (See 2 pictures) The spinner is tightened onto the old hub. For balancing, the adaptor assy is slid into the wheel for balancing between the two cones. This works a treat and take it along for my tyre guy to use it every time. With the wheels properly dynamically balanced it makes the car a pleasure to drive. There is usually no need to balance the rears.
There is now a little kit on the market that does the same job, but I beat them to it.
Hope this helps.
PeteT





PeteT

I run with 6" wide replica Twincam alloy wheels on my MGA, they look like centre-lock wheels but they are actually bolt-on wheels with a dummy central spinner to make them look like the originals.
I have had a balancing problem with them for years as they always seem to suffer from a vibration issue, usually at two of the worst possible speeds, 50 mph and 70 mph.

I have had them balanced many times but nothing seemed to make any improvement.
They were always balanced using the central hole in the wheel but recently I learned that maybe that central isn't as central in the wheel as I thought.

I was advised to try having the wheels balanced on a machine which used the wheel studs to mount the wheels instead of the so called "central" hole.

This has brought about a vast improvement in the wheel balance and the car is much nicer to drive now although there is still the occasional "shimmy" in the steering.

However, these alloy wheels have an unusual fixing system which consists of a circular plate which fits onto the outside of the alloy wheel.
In the centre of the circular plate, there is a dummy spigot which mimics the end of the "knock-off" hub and the dummy spinner is attached to the outer end of this to complete the appearance of the Twincam wheel.

The wheels are attached to the hub by special wheel nuts which are sort of top-hat shaped, with parallel sides and a square end, instead of the rounded ends of the wheel nuts on the standard MGA steel wheel.

These bolt through both the outer circular plate and the alloy wheel and there is a fair bit of slop in the fitting. So the wheel can be moved around by up to 3 mm on these wheel nuts, which probably explains some of the wheel balancing problems.

So I have been giving this some thought and I am considering turning up a couple of special wheel nuts which would be a tight fit in the holes in the alloy wheels, so that when they are installed, they will centralise the wheel onto the wheel studs.

So I could initially secure the wheel with a two of these special wheel nuts to centralise the wheel and then fit the other two of the actual wheel nuts and nip them up.
Finally, I would remove the special nuts and replace them with the remaining two correct wheel nuts before torqueing them all down.

I hope this had made some sort of sense! :^)

I have attached a picture of the wheels and the plates etc so this will hopefully help to show what I am talking about.

Cheers
Colyn




Colyn Firth

Dodgey setup
Had exactly that same problem with a friends Lotus Esprit with Simmons wheels on it-
Believe me, just centering it up and tightening the nuts up doesn't work,it will move. We were motoring along at around 200kph and hit a hole in the road causing one of the front wheels to move, it was scarey, I thought ,here we go this thing is going to fly to pieces, it really felt like the wheel was going to fly out the top of the car
The fix was some new wheel nuts with the shank the correct sliding fit in the wheel holes, apparently they had sent the wrong ones--?, maybe this is what has happened to you and the correct set of nuts will fix it

willy
William Revit

Thinking about your setup Colyn, maybe easiest option, rather than splashing out on another set of nuts would be a set of centering washers like this----

William Revit

forgot this bit, might help-!

William Revit

This thread was discussed between 07/09/2020 and 31/10/2020

MG MGA index

This thread is from the archives. Join the live MG MGA BBS now