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MG MGB Technical - Suspension upgrade

I'm slowly progressing with my RB V8 conversion. Much research has resulted in confusion about the best route for cost effective suspension upgrade. My idea is as follows and many of the problems have been reviewed but advise much appriciated.
FRONT - Replace front Xmember with CB. Thicker roll/sway bar ( what thickness?). Telescopic shocks at (low setting) , lower springs (uprated?), harder bushings.
REAR - Uprated lever arm dampers, lowered spring pickup points (as CB), Roll bar/sway bar(what thickness?), standard rate but lower leafsprings, some form of anti-tramp bar.

I have read in the archives about anti-roll bar kits using 1" on the front and also fairly thick on the rear, reports of no bodyroll but harsh ride. I would have thought that the roll bars would only effect the cornering ride, whereas heavy duty springs would effect straight line driving??
Please bear in mind this will not be used as a daily ride, so I will not to concerned about comfort, just want it to handle as well as posibble on a short budget.
Sorry for the long thread .
Brian
b bourne

Brian, I don't think that you are very far off in many respects but I would be reluctant to use anything other than standard springs and dampers. Uprated lever arms are fine and if they are too hard then you can easily replace the valves with standard ones. The trouble is that if either the springs or dampers are too stiff they can unseat the car especially during enthusiastic cornering on poor surfaces and this will actually make the handling worse. I don't think that the factory got the standard set up far wrong and remembner that they were into all kinds of competition work the results of which fed back into production. Harder bushes in the front wishbones would improve steering response V8 bushes are fine. You could also use poly bushes but this would make the ride harsher. Same goes for the rear but the best improvement here might be a panhard rod to give better axle location. I've used rear anti tramp bars but have been un impressed. Re the ARB 1" seems very stiff and personally I wouldn't want to go further that 3/4 but will leave others to comment here. Neither will I comment on a rear arb.
I'm not sure if you are converting a GT or roadster. They are both light at the rear end but the roadster particularly so and to stiffen it up very much at all might be detrimental to its handling.
Iain MacKintosh

I agree - the alloy Rover engine isn't going to change weight balance and a 5/8" or 3/4" front bar (I favour the latter) is just about right. Using 1" on these cars is something you would only want to do for competition and going above 3/4" means that you may have to consider a rear bar to balance handling.

I also agree with Iain about shocks - the stock items are just fine and you wouldn't gain much for street use with telescopics, even if you got one of the well designed kits (there are a few that are very poorly conceived).
Bill Spohn

If you change the X-member to a CB, don't you have to change the steering box as well?

I disliked the tube shock kit I purchased maybe the Ron Hopkinson(sp?) is different. I'll be changing back to OE later this year ($$).

I agree with the above on the front arb 3/4" to maybe 7/8" at the max unless you track the car. Anything more is overkill. Haven't had a rear arb (yet) so can't comment, but heard its not really necessary on CB cars.
Luigi

I have the Ron Hopkinson uprated front bar and additional rear bar on my RB V8. Having driven an unconverted V8, and mine without the rear bar, I can say it does makes the axle feel more securely located as well as noticeably less roll. The reduced compliance may well make it oversteer more in the wet, but I have found tyre choice has a much greater effect. I had a pair of American General rear tyres and the fitter said I would never wear them out. The first time I went round a roundabout I had been round a hundred times before (not all at once ...), in the wet and being tentative because of the new tyres, the back swung right out. After a couple of weeks of it was so bad I swapped the fronts and the rears over which restored things to normal, they are just way too hard for the rear in typical UK temperatures. Is it (the RH kit) worth it? Like most suspension upgrades - probably not. I also had a lot of problems with the rear bar drop links breaking. Oh, and the front bar has no locating flanges so it moves from side to side and rubs on the wheels on one lock or the other.
Paul Hunt 2

Gents
Sounds like the concensus for economic upgrades is -
Standard type dampers (upgraded), slightly thicker Front anti-roll, heavier bushes. Spring rates?
On a previous thread I got some good info about the CB Xmember, but this does seem to be the best way to go to lower the car. Any thoughts on this please + lowering rear?
Thx
Brian
b bourne

To give some idea of what I actually do (rather than say), the last two MGs I've worked on (one finished, one in process) both got 3/4" front sway bars and decambered lower A arms. The current project also has slightly lower stiffer front springs, but that's really all you could conceivably need for the street.

I have a garage full of stuff from the race cars - rear bars, modified lower pivots etc., and I don't bother using any of it on a street car because none of it does anything that really needs doing if you aren't racing. I know that this won't stop some people doing telescopic conversions etc. just because they want to be 'racy', and it is their money, so good luck to them. I hope they get satisfaction from that sort of modification - they'll probably never notice any difference driving the cars on the street.
Bill Spohn

Bill- wandering a bit OT

Modified lower pivots? i assume to raise the inboard pivot height? Or to change the relative height of the inboard and outboard pivots (I think that with the same upper pivot height and standard swivel axle length, this would yield a slightly higher front roll center.) Also brings the relationship of the inboard pivot-outbpoard pivot more level. Can you clarify the thinking on these?

Heard about these but never seen in person. Any chance of a piccy to galanf-at-juno-dot-com
greg fast

It's been said before. Most opinions on the suspension upgrade issue are suspect, in that they are comparing a worn out stock suspension with a new modified suspension.

The front suspension stock is pretty good.

The back leaf springs need to go and be replaced with steel mono leaf parabolic springs or fiberglass mono leaf springs.

A panhard bar helps in the rear and perhaps 1 size up on the front roll bar.

Rubber Bumper cars are another issue.

Barry
Barry Parkinson

There is absolutely no comparison between a standard set-up and a decent modified set-up.

I run 600lb springs, uprated lever arms, negative camber wishbones, 7/8" anti-roll (sway) bar, poly bushes on the front, with standard springs, uprated lever arms and poly bushes on the back.

The handling is transformed; slight understeer which you can convert to oversteer with the throttle. The ride is transformed too, but not for the better!

Rear axle location is only going to be an issue if you have serious power (winding up the springs) or you are looking to generate monster grip from the rears (eg racing).

It seems to me that the cheapest, most reliable and safest first-step handling upgrade is a decent set of tyres.

Neil

Neil

Neil
I agree that tires are critical. With my 67 GT I'm running 195 55 15 tires. The diameter is 5/8" less than stock. This lowers the car about 5/16' and is about 5% less circumference than than stock.

The 6" wheels and tires transform the handling. Fiberglasss springs in the rear. The rest of the suspension is stock, but rebuilt in excellent condition.

My big problem was the stock seats. I had to hold onto the steering wheel to keep from falling over in left hand turns. A set of Fiero bucket seats solved that problem. I've chased some fast Miatas through the twistys and held my own. They have more power but no more cornering.

In trying various tires on my cars, I've found that there is a huge difference between tires. The top rated tires are a major step up and handle and stick well and predictably even in wet conditions.

Moral: 1 Get your suspension in good shape 2 get wheels that are wider and 3 get good tires.

Barry

Barry Parkinson

This thread was discussed between 14/02/2006 and 21/02/2006

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