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MG MGB Technical - MGB Anti Roll Bar

I have a spare 1 inch anti roll bar, just powder coated with new bushes, surplus to requirements.

Would swap for 3/4 inch.

Can ship UK only. Paypal OK.

Colin
Colin Parkinson

Purely out of interest why are you changing? The PO had fitted a 7/8" Ron Hopkinson front bar (and rear kit) to my V8, which didn't cause me any problems until we moved to our current address. This is surrounded by 'traffic calming' (makes me fume) measures due to schools, the worst being the incredibly inappropriate square concrete 'pillows' set into each lane. I can't go over the top as the exhaust catch on both MGBs, if nothing is coming the other way I go through the middle which because of the slope on the sides and the spacing halves the impact, but otherwise I have to drive with the left wheel in the gutter and the right wheel over the top to clear the exhaust.

That was when I started getting a spate of broken near-side front drop-links. I put this down to the thicker ARB and the large difference in forces on the drop-links tending to pull the near-side one apart with one wheel in the gutter, so changed it for a 5/8". Not only did the car feel happier going over them with one wheel in the gutter, but no more broken drop-links in the fifteen months since. The irony is that with a broken drop-link i.e. no front ARB at all I'd not noticed any change in handling anyway. But then I don't go swerving in and out of traffic cones on a day-to-day basis.
paulh4

Hi Paul, I have 2 of these so I can sell one, and think it is too hard for a road car. My race car uses 1inch.

Colin
Colin Parkinson

Found this about anti roll bars which i have added to my blog at https://mymgbinfo.wordpress.com/2019/04/16/anti-roll-bar-stiffness-comparisons/
I am surprised at the difference the extra 1/16th makes.
steve livesley

"The chart shows that the thicker bar makes the front suspension over 4 times stuffed."

Too true, mate.

Can't say I'm surprised given how reducing my POs 7/8" to 5/8", although my info says a 9/16" was optional on the CB roadster originally, and initially on RB GTs and roadsters in 76.

A thicker bar does not stiffen the suspension as such, only in corners.

Also uprating the front bar meaning you remove the factory front bar goes against what others say, like for the RH kit, where fitting a rear bar you should uprate the front.
paulh4

My 75 B is a CB conversion and i can see where the rear anti roll bar has been removed which i believe must be removed due to suspension been lowered. Why is that?
steve livesley

I don't know if it 'must' be removed, or that it can be removed.

I think the rear ARB was introduced on RB models, in order to compensate for the increased ride height. Having said that, I thought the earlier RB cars didn't have it.
Dave O'Neill 2

Lindsay Porter's book says that from August 1976 G-HN5 410001 a thicker anti-roll bar at front & anti-roll bar at rear fitted as standard.
Cheers, Charles
Charles9

Clausager concurs, although June 76 at that chassis number for the start of the 77 model year.

I don't see why it couldn't be removed, nor why it would need to be removed with lowered suspension, unless at full compression something was fouling.

Are you sure they are the mounting points? The handbrake arrangement was also different on late RB cars, with the cable going to a rubber flap on the near-side axle tube adjacent to the ARB bracket, and a metal rod going back to the off-side wheel as in the attached, instead of cables on a metal lever on the diff casing. However that change didn't happen until August 76. 77 and later also had the forward-mounted radiator and electric cooling fan.



paulh4

Do you think that "stuffed" is a typo? should it read stiffer?
Never heard the word used in MG speak before except maybe as part of an expletive. :-)

I swapped the 5/8th" front anti-roll bar on my MGA for a 3/4" one and it really has improved the car vastly.
It handles really well now, corners with virtually no body roll and lots of front end grip in the dry or the wet.
I has otherwise standard suspension apart from a pair of adjustable rear lever arms shocks.

I think the 1" ARB would probably be too much for my car on the road and probably make it lose front end grip in the wet. If it was a "Track Day" car though I may well be tempted to try it on the car.

My brother-in-law has a very nice 77 RB mgb roadster which has been converted to CB. When we were doing some work on it last year I noticed that it still had both front and rear standard ARBs fitted.

I had wondered if maybe the rear ARB should have been removed once the car had been lowered?
Any opinions from you MGB guys about this?

Cheers
Colyn
Colyn Firth

My understanding of the rear anti-roll bar on the MGB is that you don't have to remove it if you lower a rubber bumper car, but that you safely can if you like. With a rear drive car like the MGB the perceived wisdom is that the car handles most predictably when the front is stiff and the rear is compliant. This set up allows the back end to move gently into roll oversteer so enhancing your driving experience without the danger of the back snapping round and sending you into the hedge.

The chrome cars didn't have a rear ARB, but by jacking up the suspension for the R/B car they spoiled the handling by raising the centre of gravity and adding heavy bumpers fore and aft, thus making the car roll too much, hence the rear ARB. If a R/B car is lowered to C/B height, the necessity for the rear ARB is no longer there.
Mike Howlett

Thanks Mike,
has anyone actually done a back to back trial to see what difference removing the rear ARB would make to an RB car that has been converted back to CB?

When my brother-in-law first got his car he found that he lost the the back-end of the car very easily. He did kind of throw the car into the corners at first but he takes it a bit steadier now.

I was wondering if removing the rear ARB would reduce the over-steer a little?

Cheers
Colyn
Colyn Firth

Colyn,
what were the tyres like on your b-i-l's car, perhaps loads of tread left but many years old, hard with age and/or lack of use or perhaps even unsuitable and/or "cheap" ditch-finders, uneven wear, uneven pressures, mixed makes and models - or perhaps they were suitable new but worn-in correctly, at correct pressure, matched pair (and to front tyres), performance tyres to suit the driving style.

Many forget the basics before moving on to more sexy tuning of suspension and handling.

Of course the best tuning, handling and safety upgrade that can be made to any vehicle is ...




driver training (and I needed it as much as anyone).
Nigel Atkins

Colyn
Definitely.
Rear antirollbar on live axle promotes oversteer much more than on irs.
Antirollbars generate two opposing effects:
Increased lateral grip from better wheel geometry due to less body roll.
Reduced lateral grip due to weight transfer to outside wheel.
For live axle rear are combination, the weight transfer is where the bar is (the rear) so lateral grip at the rear is reduced.
The geometry gain is all at the front due to the fixed wheel angles of the live axle, so front grip is increased with no offsetting weight transfer there.
Perfect combination for oversteer and early rear end breakaway!
Had a friend, experienced track driver, who none the less wanted to try one at a track day years ago. Two spins in the first lap and he was back in the kits removing it. And believing me. While I said nothing as someone else offered to buy it from him.

And if any further roof is needed look at the Escort rally cars, set up with rear arb to generate that well known and beloved sideways is the meaning of life attitude in rally stages :-).
Paul Walbran

Tyres are almost certainly the biggest variable in how easy it is to hang the tail out. I replaced a pair on the back and the first wet time on a particular roundabout on a daily commute the back went out horrifyingly easily. To avoid tip-toeing everywhere I had to put those tyres on the front where they were OK. They were Generals made in America, and a pal in Sacramento said even though his company had a discount scheme with General no one bought them as they were so bad even there. I did wonder why the fitter said they'd never wear out - way too hard. Fortunately they did, eventually.
paulh4

Apologies to Colin for hijacking his thread about 1" front ARBs, at least we are still talking about ARBs.

Thanks to Nigel, Paul W and Paulh4 for your advice.

There may be something in what you say about driving

training Nigel.

The B-I-L in question got very close to setting my MGAs brakes on fire on a very long descent down one of the higher Alpine mountain passes a few years ago.

His driving "technique" was to accelerate hard down the steep straight sections in either 3rd or 4th gear and then, without changing down, brake extremely hard all the way round the hairpins!

This promoted a surprising amount of body-roll, tyre squeal and felt awful.

I kept telling him to change down a gear or two and brake before the hairpins, then power into the bends like I do. But I don't think he really understood that this makes the car so much more stable through the bends and the car corners much flatter.

When we reached the bottom of the pass and parked up, there was a thin wisp of blue smoke rising from each wheel arch of the car!

Looking back, I think that it was very fortunate that we ran out of mountain just a minute or two before we ran out of brakes!

The upside for me was that this scary driving experience pushed me into replacing the 5/8" front ARB with a 3/4" one, which makes the handling so much better.

Also, my B-I-L enjoyed the experience so much that now has his own MGB.

Cheers

Colyn

PS. I also swapped the burnt out Greenstuff pads with a new set of Mintex M1144 pads and these too have been a vast improvement.
Colyn Firth

Colyn, you're a saint, if he'd driven like that in my car against my advice and then instruction he'd have walked home no matter where we were or who he was, gawd herself or SAS instructor.

Gawd only knows what his B must really be like, put his reg up so that we can all pull over to avoid him, there's spirited driving and there's being too silly on public roads.

I hope he's calmed down.

I shan't sleep tonight now.


Nigel Atkins

Thanks for comments above re rear arb. My 75 would not have had front and back arb originally but a PO back in 2012/3 used the car for racing when it was a RB. He added a 7/8" front arb and modified the chassis to take rear arb which since removed when a following owner detuned engine, converted to CB and lowered suspension - and removed rear arb. This is my first B so cannot compare to others but it certainly corners well. Would like to know more of it's racing history - a guy called Mike Lawton (Spilsby area) owned it 2011-4 and sorned it whole time yet MOTed it each year and clocked nearly 1500 miles - so must have done a fair bit of racing (or track days).
History i have discovered to date i have added to my blog at https://mymgbinfo.wordpress.com/my-mgb-a-brief-history/
Anyway sorry for hijacking thread - think will leave arbs alone for time being.
steve livesley

Sounds like the Ron Hopkinson kits the PO added to my 75 V8 then. Had problems with both - rear drop-links breaking until I modified them, and the front factory drop-links breaking when we moved to an area with a lot of speed humps as described way back.
paulh4

Think i read somewhere that the mgb performs best "stiff at front, sloppy at back"
steve livesley

IMHO
7/8" bar is about as far as you need to go without a rear bar
With a rear bar as on a rubber bumper car, with a decent set of mounting bushes a 1" bar or bigger can be used depending on spring choice
A decent pair of 675-700lb front springs and a 7/8" bar transforms a B into something that actually handles like it should
Depends on how fast you drive really and what you want out of your car

willy
William Revit

Nigel
Sorry, I have been offline for a week or so, I have some follow up info about the MGB for you.
Cheers
Colyn
Colyn Firth

Colyn, I hope so I've not slept since, I've bags under the bags under my eyes!
Nigel Atkins

This thread was discussed between 16/04/2019 and 05/05/2019

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