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MG MGB GT V8 Factory Originals Technical - oversteer
|last weekend i was driving my MGB V8 on a small circuit at a MG club event.My car is a V8 roadster 1975 lowered RB with standard shocks and a 3/4 a.r. bar at the front.I was great fun putting the power on the circuit and i hope to do it again in a few weeks. |
I drove the car before the modifications (RB height and no AR bar) and foud it oversteerred, but now it is oversteerred (tyres 185/70/14, tyre pressure 2,5 bar) and I rather have a bit oversteer again in fast curves.
Where should I start, tyre pressure, changing shocks (front?? rear??), stiffer shocks??.
What's your expirience??
ditch RB's increase front roll bar 7/8 uprate front shocks try, then add neg camber.
|I guess you have gone from understeer to over steer ?|
Lower front tyre pressure should keep the car neutral but there are so many variables in these old cars -
Before you follow Paul's advice you might consider whether you have lateral movement in one of your front shockers. Always assuming that all the bushes were renewed when the car was lowered.
|I have been considering this issue of late. My 78 came with swaybars from the factory, after the conversion I have been unable to use a front swaybar due to clearance with the crank pulley.|
What is the "performance" setup for swaybars on a B? 7/8" fron and 3/4" rear? let me know. I am making some solid mounts for the rear swaybar as I twisted the stock ones up with the axle twist from the V8.
Try this for sorting tyre pressures.
If you want to add oversteer reduce front arb or add a rear arb.
|Arno - I'm not sure I understand your question....(Too many oversteers). As for Larry - are you running with a rear bar only and no front on a V8......Ooooh loads of oversteer! If you can't fit a front bar, ditch the rear quickly until you can get a front fitted. A RV8 bar is bent to accomodate the pulley wheel and could be your answer. You will roll all over the place without any bars but at least you'll be slightly balanced.|
...unless you like loads of oversteer that is :0)
|Stuart,my question is confusing, my problem is that understeer now after lowering the car and fiting he 3/4 ar bar, what i want is neutral and power oversteer.|
My setup is no AR bar rear, 3/4 AR bar front, lowered front springs (AHT 21)- 4 cm, lowering blocks between axle and springs in the rear - 2,5 cm, V8 or polyurethane rubbers and standard shock's.
The B tends to oversteer and adding V8 grunt adds more power oversteer, so taming the rear is usually the way to go.
Fitting a 3/4 roll bar is the only change reducing front and adding to rear grip making car understeer more. If you really want to change to more oversteer then consider roll as Stuart mentioned and if you prefer it now then add a rear bar if you prefered the roll as it was then reduce front bar, but you are going against the grain unless grass track racing or rallying and wish to make back end loose.
|Since yours is a RB model fit the rear ARB again. This should balance the bar a bit more by adding more oversteer. (Some threads have also suggested the rear bar adds some anti tramp but without looking underneath now I can't remember the layout). Remember tho anti roll bars reduce grip but add to stability when changing direction. Check http://www.dsm.org/menu.epl?item=352 for some really good info on roll bars / grip stuff.|
After my 3.5 Rover conversion I also had a problem with the crank pulley hitting the sway bar under hard braking. I overcame the problem by packing the bar down with aluminium blocks (2" X 1" X 4") under the mounting brackets and obviously longer mounting bolts. Looks perfect and works the same way.
|I can confirm the use of aluminium blocks as mountings for the front anti-roll bar. If you don't want to make them you can get them from V8 conversions but, of course they are very easy to make.|
Mine have bolt holes recessed into the blocks about 1.5 inches and I am using allen bolts to fix them to the car. The the anti-roll bar is bolted onto the block by means of its standard brackets. Check the angles of your anti-roll bar. I found that on one side it was about 60 degrees and the other about 65. I couldn't figure out why it wanted to travel to one side all the time when the steering wheel was turned. Heating the bar and correcting the angle made a lot of difference. I also welded a thin stop onto each side to make sure that there could be no lateral movement at all.
When my had the early type of conversion in my car, (engine further foward) I made some offset frame mounts for the sway bar. Now that the engine is back further I put the sway bar back to the stock location. I can fill you in on the details at Bellevue, if interested.
|Just an FYI (Thanks for all the ideas) but I am running a Ford 302 not a buick. Unfotunately, spacing down the sway bar is not an option as the bar right now would pass though dead center of the crank pulley, so I would need a good 5" drop, to much to use blocks for. I have removed the rear swaybar, but the car heals over very badly now and I notice more axle wrap and wheel hop. I will be making stouter mounts for the rear bar and re-installing it, oversteer is controlable if you keep you BIG FAT FOOT out of it, which for me is a challenege but will teach me some restraint!!|
Keep the ideas coming, especially about bar thickness, that is something I want to address even if I get a custom front bar made..
|See you there bill, as usual your car is the grand Guineapig! I will have mine there so you can see what I am working with, maybe we can brainstorm a simple solution.|
I can attest to the anti-tram qualities of the stock rear sway bar. While it is not a perfect anti tramp device, it's layout does make it effecting at limiting wrap-up. This can be evidenced by the twisted up stock mounts I found when I removed my rear sway bar a few weeks back. I will be making solid alum block mounts for my rear hopefully this week.
|As with Larry, I can confirm the anti-tramp qualities of the standard rear anti-tramp bar. I know that a few of the guys in my area have needed to fit anti-tramp bars on early model 'B's, but on my '79 rubber bumper I haven't. I compete regularly in hill climb and circuit sprint events and on dropping the clutch and under hard excelleration, the rear tyres just 'Light Up' without a trace of axle-tramp. And that is with a limited slip rear end.|
This thread was discussed between 18/07/2002 and 21/07/2002
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