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MG MGB GT V8 Factory Originals Technical - How to uprate suspension

Hi All,

I am mightily confused about what to do regarding my suspension set up.

I will be moving a standard RB front crossmember+steering over to a CB car. So RB front end and CB rear.

I need to uprate it I know, but what I have read on line varies from simply using a front anti roll bar 3/4" thick and V8 lower wishbone bushes, right the way through to buying V8 wishbones, V8 kingpins, V8 shcokers/damper, V8 rear springs et al.

Some web sites offer a 'V8' version of every part of the suspension there is and seem to impy I need it all!

Q/ What specific parts do I need to replace ?

I think I will also need to lower the front, but only the front - am I correct, and does that just involve fitting a lower set of V8 springs?

..and I thought brakes were confusing!
Liam

I'm sorry, but what on earth is possessing you to ruin a great suspension system by swapping in a rubber bumper crossmember? I understand & agree with the steering swap, but why the crossmember? You don't actually believe that book, do you? Are you going to move the engine forward as well?

Appologies in advance to all I have offended, but having done 5 conversions, 4 rubber bumper cars swapped over to CB crossmembers, & a CB car with a Buick 300 which is taller than the Rover/215 engines, I don't understand using a taller crossmember you then have to compensate for by using shorter springs & whatever else to imitate what you just threw away.
Jim Stuart


I totally agree with what Jim wrote... (My '71 has it's original crossmember, with no modifications at all, and I'm also using the original steering rack. One day I may change racks.)

"V8 wishbones, V8 kingpins, V8 shockers/damper, V8 rear springs et al." I didn't even know such things were available. They CERTAINLY aren't necessary, and even if you decide you want them, you can always save them for "phase two". It would be prudent, however, to make sure your current suspension is in good repair, and that your front-end is properly aligned.

Tires are the most important suspension decision by far.

At least in the states, most people install a non-MG rear axle because that's the most economical way to change gear ratio and upgrade to a limited-slip differential. After that, IMHO, fitting a well-designed Panhard rod will give the most noticeable improvement in handling.

V8 bushes are probably a good idea on all MGBs, not just V8s. They're cheap, easy to install, and I suppose the decision is even easily reversible.

Is your car a roadster or GT? That will have a lot of bearing on anti-roll bar selection, but probably the best idea is to simply drive the car and decide based on how it feels. (I'd bet most of us have gone "up" one size on our FRONT bar, and probably NOT changed the rear... but it'd be interesting to see a survey.)
Curtis

I think you should change the body from a CB to a RB and keep everything else as is LOL

Humor is best when....
Steve Bacon

Jim Stuart,

In your "RB swapped over to CB crossmember" conversions did you retain the CB steering rack? If you retained the CB steering rack did you modify the shaft to include 2 uni joints? I am interested to hear more as I am going down a similar path (RB shell & CB crossmember).

Regards,

Dom
Dom

I have a late chrome rolling shell already - 75?

So if I choose to keep the CB crossmember all I have to do is use the double UJ steering rack and move the Anti roll bar forward a touch for clearance?

Is that right?

Does the dirver side bulkhead where the steering column emereges still need altering, I know the passenger side still does ?

I might recall reading somewhere that very late CB cars came off the line with some of the engine bay mods done as per RB? Is that just my tired brain making it up or is it true?
Liam

While I must agree that the CB crossmember is a better way to lower an MG. The RB cars can be lowered with good results. Also, I think the RB rack is plenty quick. The CB rack is quicker and would be too twitchy at high speed for me.

I lowered my '79 BV8, probably not even the best of ways, yet it is so much more fun to drive. The only drawback is the bumpsteer. I enjoy the excitement & can "catch" it. Makes me worry when my wife drives it, though.

Listen to Curt on the panhard rod. I resisted putting one on a leaf spring car for a long time. Man, what a difference. Oh, and the stickiest tires you can afford to wear out. Yeeehaaw!
Carl Floyd

I always use the RB steering rack. I like the lower steering effort with the much larger than stock tires & wheels, normally(for me), 195/65/15 stickies.

By altering the angle the rack mounts to the cross member & shortening the steering shaft, I have not had to add any U-joints, but my cars drive on the proper side of the street, that is the driver's right. You can remove the cap below the rack & remove the steering shaft & substitute a wood dowel to do the checking for alignment. Use the smaller late model U-joint at the bulkhead.

I have used poly bushings everywhere on my cars, including the pads between the cross member & body. They last longer than the V8 bushings and are very easy to remove. My last car has a panhard rod & I will always use one in the future.

My CB car had both bulkheads modified to set the engine back as far as practical. I would splice in the steering cone from a RB car, if at all possible. The later(including some CB cars) steering shafts are 2 piece D sections and this upper shaft is somewhat variable in length which gives you more adjustment in rack angle & lower shaft length.

You really need to have the engine & headers installed before you can start placing the steering.

Simple lowering blocks work well in the rear with no known drawbacks.
Jim Stuart

Dom,
I understood that you were going to make up your own through the guards extractors. If thats the case you can make them to bend around the steering shaft and save alot of sweat.

Peter

Liam,

If you do use the RB cross member, and lower it to an equivalent CB ride height, then the lower wishbones will be inclined from the horizontal. Dependant on how low you've gone, this may contribute to a bump steer issue, conclusion is stick with the CB x-memebr as a preference.

Regarding increasing front roll stiffness with the addition of a 3/4 anti roll bar. I would leave the roll bar to last, evaluate the car's characteristics then decide which mods are required. Remember; to reduce understeer reduce the front roll stiffness (i.e. reduce bar diameter or coil spring stiffness) to reduce oversteer increase the front roll stiffness. A increase in the rear roll stiffness is equivalent to a reduction in the the front, i.e. it's vice versa. I would recommend 0.5 to 1 deg negative camber, and many people recommend the panard (I have not tried yet), again fit these before final tuning of the roll stiffnesses.

I would not recommend persevering with the old dampers, fit a set of of telescopics, and again tune to requirements. I have a set of spax 1/16'clicks rear 7/16 front.

I have a set of 6 leaf rear springs which I had reset lower by a company in London (Brost Forge Ltd, Unit 7, Roman Way Ind Est, Roman Way, London, N7 8XH, Tel: 020 7607 2311) I imagine you can find some where closer to Tyneside.

Regards, James

J E G Eastwood 1

Thanks for all your advice everyone, plus the people who emailed me direct.

I'm a bit nearer a decision ! but there are a lot of issues here to think about. I think I may start down the CB crossmember route and only change to the RB if I'm having serious fitting issues. Ideally I would like the RB steering column top end because the dash on the RB donor is in much much better nick than the CB one.

At least this way my problems will be confined to the column fitting itself rather than spread out over crossmember removal, refitting and the rest.

Still, the first task is engine and box in and aligned first.
Liam

This thread was discussed between 18/12/2005 and 29/12/2005

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