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MG MGB GT V8 Factory Originals Technical - Quick Roll-bar question

What size front anti-roll bar would you recommend for a '76B with Ford 302?



On standard or uprated springs I would recommend the 3/4 inch. This assumes you have a 6 leaf rear.

Be aware that the spring stiffness of the roll bar increases to the fouth power of it's diameter. i.e. a small % increase in diameter will have a significant effect.

James, UK
J E G Eastwood 1

Is your engine forward of the heater or the heater removed and engine set back. If you have engine weight forward or have a rear bar I would go 7/8. I would also check with Addco; good quality and lower prices. I plan on 7/8 front,11/16 stock rear with custom u bolt mounts toward center more for axle location. Moving the mounts in decreases stiffness.
JN Jim

I use a 7/8" in front & a stock 11/16" in the rear (both in urethane bushings) with a Buick 215. For a 302 Ford, I would use the same or consider going to 1" in the front.
Carl Floyd


I should also have mentioned yesterday;

If it understeers - stiffen rear or ease front.
If it oversteers - lossen rear or stiffen front.

The over/understeer characteristic will also change with throttle, as another force vector is added to the lateral at the rear tyres.

My set up is 480 lbs front, 3/4 front bar, 6 leaf rear with no bar, inch lowered, 0.5 degree negative camber front and telescopics all round. Rover 3.5L engine. This gives the following dry handling characteristic.

Ballanced/neutral throttle - Mild understeer. (i.e. constant speed in any gear)

Full throttle 1st - Oversteer
Full throttle 2nd - Mild oversteer
Full throttle 3rd - Neutral
Full throttle 4th - Mild understeer (I don't like an oversteer car at these speeds..!)

J E G Eastwood 1

There are many other important factors that haven't been discussed yet in this thread. The torsional rigidity of the overall car is one of them... that's why roadsters and GTs came with different bars. If you do anything to stiffen up your chassis (like adding a cage) then the roll bars will be perform more efficiently. A rusty, tired old chassis will have noticeably less rigidity.

There are enough factors that you should be weary of specific advice from anyone who doesn't have their car set up just like yours. If you change ride-height, tire/wheel size, track (i.e. side-to-side spacing of tires), or roll-bar mount stiffness (e.g. urethane mounts or aluminum pillow blocks) you'll affect roll stiffness/performance. You're probably planning on using radials on a car that was originally designed for bias ply tires... How and where you drive the car and personal preference are also important practical factors. Frankly, a little understeer makes cars easier (and arguably more fun) for less attentive or skilled drivers to drive.

I recommend you get the car built, on the road, and well sorted out (e.g. with the front end aligned and tire pressures set) and ONLY THEN start tuning roll stiffness from THAT point.

This thread was discussed between 21/02/2006 and 26/02/2006

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