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MG MGB Technical - Void Bushes

Has anyone succeeded in sourcing replacement void bushes for the extreme ends of the rear anti roll bar.

mark smith

Mark,

Part number 21H6655? MGOC have them listed at about £50 but I suggest you lower the suspension, fit a thicker front bar and throw the rear bar away.

Geoff
Geoff King

Unless you fit some sort of anti axle wrap device I would not throw away the rear bar. Course yours sounds like it is tired, but by design the stock rear swaybar is also a way of limiting extreme exle wrap.

Ask me how I know after many drag races with my V8 and pulling my rear end to swap in a stronger unit... Talk about bent up metal. That will be fixed when the new rear end goes in.

It is true you want a heavier bar up front than the rear. I think many people put a bigger bar up front and leave the rear as stock.
Larry Embrey

I'm confused Geoff says scrap the rear anti-roll bar, and Larry says keep it.

As a rank amateur, I haven't got a clue which way to jump.

Also considering the cost of those void bushes, compared with the cost of other bushes on the suspension, they sound rather expensive. Surely no-one is paying these prices, sounds like a rip-off.
mark smith

Mark,

When the MGB was first designed it didn't have either front or rear anti-roll bars. It quickly became obvious that a front bar would improve the car no end and it became standard. When Ralph Nader and co. decided to force the safety bumper on us, MG had to raise the ride height of the car to get the bumper to the correct height for the US market.

This effectively ruined the handling of a perfectly nice little car as it now tipped over alarmingly in corners. To counteract this they fitted a rear anti-roll bar.

Now, you don't have to be worried about the ride height and you can buy a kit to lower the car to the original ride height. If you do this and throw away the rear bar, the car will be much nicer to drive and will corner in a safe and predictable fashion. Many owners increase the size of the front bar to further improve the car. I have done this on my car and MG themselves used to offer the thicker bar as a tuning upgrade.

It's up to you what you do with your car and many people leave them as they are, but that's what Geoff was talking about.

The main thing is to enjoy it!
Mike
Mike Howlett

You say I can buy a kit to lower the car to the original ride height, and in doing so throw away the rear anti roll bar.

Can you explain if this kit will work with RB springs, because I bought a new pair a couple of years ago, brand new, which I have yet to fit.

Also what does this kit consist of, and finally if I go this route, I note I will have to buy a thicker front anti roll bar, what is the old and new size.
mark smith

You don't have to do any of this, but if you want to see the kit, copy and paste this link into your browser
http://www.mgocaccessories.co.uk/acatalog/MGOC_Accessories__Handling_26.html

On this page you find the R/B lowering kit as offered by the MGOC. It comprises lower front and rear springs and various rubber bits and bolts. It doesn't include the rear shock absorber links that you would also need, unless you have telescopic dampers on the rear. The kit costs £124.95. On the same page you will also find the up-rated front anti-roll bar which is 3/4 inch thick instead of the standard 5/8 inch. This costs £35.00. You can get even thicker ones, but they probably aren't necessary on a road car.

If you have already invested in new rear R/B springs, you will probably want to keep the car as it is. You will be amazed how much improvement fitting new rear springs can make. If you don't lower the car, then keep the rear anti-roll bar.

I hope all this makes sense to you!!
Mike
Mike Howlett

If I fit one of those fancy and very expensive front end suspensions to my RB, what exactly do I have to buy to bring the rear suspension up to scratch.

I have already acquired a pair of Spax shock absorbers, for the rear, so if someone could just list the bits, I will be on the right track.
Alex

Mark
It's a personal choice thing. The racers stiffen the suspension, front more than rear, lower as far as possible and don't bother with the rear roll bar. That's where Geoff's coming from.
On the road, there's not much of a difference in normal use, but the roll bar does offer some degree of sideways location of the axle. If you have the technology, take the rear bar off and try it out.
Dave
Dave Wellings

Alex,

What ‘fancy and very expensive front end suspension’ do you have in mind?

You will probably receive several different opinions on what should or could be done to the rear suspension and there is not a simple answer. It depends on many factors including your budget, what compromises you are prepared to accept and how original you want your car to be. I’m fitting a John Hoyle IRS with his front kit but this is not the cheapest route and the car is far from original.

If you want to lower the car to chrome bumper height but retain the existing axle you could simply use lowering blocks (and your Spax dampers), unfortunately this will increase the risk of axle tramp which you may or may not consider to be a problem. Anti-tramp bars could be installed to control this, the RB rear anti roll bar offers some control of axle tramp but not much (especially if the bushes and mounts are worn). As an alternative to lowering blocks lowered springs could be fitted, per the MGOC kit Mike refers to above. Lateral location for the axle may be a problem resulting in tyre rub (exaggerated by lowering the suspension) and a Panhard rod could be fitted which will reduce the axle movement under cornering forces.

The choices are many, but in order of cost something like this.
Do nothing. £0
Remove or retain the rear anti-roll bar? Try it and see what you prefer. £0
Poly bushes. £25
Lowering blocks with uprated lever arm dampers or your telescopic dampers. £35 + dampers
Or lowered leaf springs with uprated lever arm dampers (and CB drop links) or your telescopic dampers. £90 + dampers
Optional anti-tramp bars. £200
Optional Panhard rod. £350
Or independent rear suspension. £2,500K


Geoff
Geoff King

Great Scot Geoff, so many options.

I was thinking of saving up for that RV8 front end, as shown on Mike Howlett's link:

http://www.mgocaccessories.co.uk/acatalog/MGOC_Accessories__Handling_26.htm

I'm not interested in racing, just giving the car the best possible ride configuration, for me to have a decent ride around the block, every now and then.

Everyone talks about lowering the RB cars to CB height, and I must admit that visually, a car sitting on the deck like a cat, Jaguar perhaps, is better than one with it's ass stuck in the air, if you will pardon the pun.

I get the impression from Dave Wellings that most changes are race related.

I want the car to look squat, and ride like a Lotus Elan, a car that was truly glued to the road.

Given that I will sort out the front suspension, and will probably fit a pair of Spax shock absorbers to the rear, listing the bits for that particular approach would help enormously.
Alex

Geoff,

Having bought a chrome bumper shell to replace the smashed rubber bumper one, I now find the lowered rear springs are in fact too low (Tyres rubbing when cornering hard, and damaging exhaust on sleeping policemen ).

About 1/2" would make it right (measuring chrome strips to wheel centres front & rear) and it occurs to me that I could achieve this by lengthening the rear spring shackles slightly (not to hotrod length, just 1/2" or so.) It's a cheap way to go, possibly rear suspensions could also be lowered slightly by shortening the shackles.

I expect lots of theoretical arguments against this (as usual in these threads) but has anybody actually tried this ?

Mike
Michael barnfather

Alex,

You can certainly make the car look squat but it will never ride like a Lotus Elan.

The RV8 crossmemeber is horrendously expensive and unless you insist on ball joints probably doesn’t offer much advantage over the standard B set-up. Wheel bearings are not far short of £200, if you can get them. Have a look at the John Hoyle front kit http://www.hawkcars.co.uk/mgb/index.html or http://www.ngcars.co.uk/options/optionsframe1.html vented disc brakes can be fitted, if that is what you want.

Assuming you sort out the front of the car and lower it to CB height you need to lower the rear of the car (to make it look squat). Either fit lowering blocks or lower leaf springs with your telescopic dampers. Most MGB parts suppliers like MOSS, MGBHive, MCOC etc will have both options available. You should also fit CB type axle check straps; again these are available from most MGB parts suppliers. In my opinion the lower springs is the best route, more expensive but if you are considering the RV8 crossmember I guess cost is not much of an issue.

At the front fit a thicker anti-roll bar (3/4 or 7/8) and try removing the rear anti-roll bar, but if you prefer the handling with the rear bar put it back on.

Your shopping list should be:
Front suspension kit of your choice (or shorter front springs if you want to keep costs to a minimum).
Thicker front anti-roll bar.
Lower rear springs (or lowering blocks)
CB axle check straps.

None of the above is for racing, it will simply make the car lower (but not necessarily stiffer) and will reduce roll.

Geoff
Geoff King

Geoff, thanks for your comments, I'll take them in over Christmas, assuming I can see straight after one or two stiff drinks.

Alex

Another viewpoint here. If you can find one, perhaps the cleanest way to deal with the front suspension is to simply swap in the CB crossmember. Cost is whatever you have to pay for one but could be quite cheap. On the front swaybar, I can't go look and memory may not be completely reliable, but Mike mentions a 5/8 swaybar. I thought it was smaller at least on the CB, but what I do recall is that the GT awaybar was thicker than the roadster's by 1/16", and this was enough to tell the difference when fitted to the roadster. Since every increase in the swaybar diameter brings a corresponding decrease in ride quality, keeping the bars to a minimum helps the ride. I also suspect that in addition to fitting a rear swaybar to the RB cars the front swaybar may have been upgraded, which means that if the suspension is lowered, the bar may already be plenty stiff.

In the rear, another alternative is de-arching the springs. For a small fee, a spring shop can take your new rear springs and de-arch them per your request. Even doing this twice or more is cheaper than new springs. I had CB springs de-arched 1-1/8" and added 1 full leaf which put me at exactly the right height and stiffness to match my Huffaker -1" front coils. The shocks can be tuned to match by changing oil. YMMV

Having taken a CB car 2" lower than stock, (1" with suspension and 1" with tires) I can tell you that the stock CB GT front rollbar only, is enough to do a fine job of controlling body roll for that configuration. As the ride height is raised more roll control helps.

Jim
Jim Blackwood

A 9/16 front anti-roll bar was an option on UK roadsters up to ’67, from ’67 to ’74 it was standard. ’75 to ’76 (early RB) didn’t have one at all then a 5/8 bar was fitted ‘76 on. GT’s had 5/8 from ’65 to ’74, 9/16 from ’74 to ’76 and back to 5/8, ’76 on. Roadsters and GT’s had rear bars from ’76 on.

If you are used to the relatively flat cornering of a modern car then a ¾ or 7/8 bar is not excessive. Increasing the diameter of the front bar increases understeer, reduces roll and may make the ride harsher but this also depends on spring and damper rates, add the possibilities of a rear bar, springs and dampers and the permutations are endless. Handling, roadholding and ride quality is a personnel thing and only the individual can decide which he or she prefers.

To ‘simply’ swap in the CB crossmember won’t be the easiest way to lower the front. It can be done but the steering rack mounts on the RB crossmember are not the same as the CB and would need to be modified. The easiest and quickest way is to use shorter springs. The TCA angle changes and the bump to rebound camber will be different but for normal road use it works fine and Alex is not looking for a race set-up. With a simple, no cost, modification to the bump stop total suspension travel can be the same (RB compared to CB compared to lowered RB).

Probably the cleanest way to lower the RB front is to use raised stub axles but I have never seen them for sale this side of the Atlantic. If anyone knows an UK supplier or a US supplier that will ship to the UK and the cost is not prohibitive I would be interested.

I agree de-arching the leaf springs is an alternative for the rear but ‘small fees’ don’t seem to exist over here and I suspect the difference in cost between new and de-arched springs would be minimal.

Alex, if you were not confused before I guess you are now. Let us know what you decide to do.

Happy Christmas,

Geoff
Geoff King

Confusion is not the word, however I can see sundown approaching so I guess that's as good an excuse for a wee dram as I'll ever have, and guess what, it's amazing how clear all those problems become about halfway down the bottle.

Merry Christmas to all.
Alex

This thread was discussed between 13/12/2002 and 24/12/2002

MG MGB Technical index

This thread is from the archive. The Live MG MGB Technical BBS is active now.