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MG MGB Technical - Suspension questions

Now that my V8 rover powered MG is done. I'm looking to the suspension. Currently it is in good condition and bone stock with the exception of Urethane front bushings. The rear is bone stock in good but original condition.

At speed (85ish and up)the suspension "nibbles"? and bounces around a bit making the car feel unstable. I want to improve the ride, high speed stability and handling. I use this car almost daily. So It's more GT (grand touring) than full race. I want to increase suspension compliance and reduce body roll.

I have seen many many different solutions posted here and there. Some look like they might work, other look silly like the out board front shock kit moss sells.

all input is appreciated.

Mark.
M Mallaby

Hi Mark,
The suspension "nibbling" at 85 and up is not normal. It should be rock solid at 85 on a good road. I would advise to keep stock set up but find out what the problem(s) is/are. What kind of wheels do you have (stock,wires,width, etc.) -J
jjralston

Wheels are stock Rostyles, balance is good. tyres are 185/70-14.
M Mallaby

Put in the biggest antisway bar at the front you can get. Mines a 7/8 th.

How good are your shockers? They might be a bit worn.
Try the bounce test on each of the four.
I think armstrongs in good condition are just fine.
Are they topped up with oil?
How is the steering alighnment?

I've hear tell of Harmonic vibrations that can be caused by the tailshaft not having the same angle on both universal joints. I've never noticed this on my V8 conversion, but I might have got lucky.
Peter

Tyre pressures? Check them with a known good gauge, forecourt ones can be wildly out. My car with a 3/4" front ARB and an ST spoiler is rock steady to over 100MPH, on a track or in Germany of course.
Stan Best

The rostyle wheels should be spin balanced on yhe car, or balanced off the lug hole pattern (few shops anymore do either). when the are balanced off the center hole the can check perfect on the machine, but still be off (the hole isn't always perfectly centered), causing anything from a slight high speed vibration that's hard to pinpiont to very noticable vibration (been there done that). Don't assume it is definatly not wheel balance, that combined with worn shocks could cause the "nibble" you descride.
Robin Meier

Thanks to all.

The shocks are in good condition. the ARB is stock. Does the 7/8th inch sway bar make the car loose? I will look at getting the wheels ballanced using the bolt holes (good catch). On our freeways in Southern California there are rain sipes and the surface is not smooth but rather a lot of small bumps. On a smooth road the car is fine. I'm looking for ideas to help design a suspension that will handle well as well as soak up these freeway bumps.
M Mallaby

Mark. I am not sure what the descriptive term "nibbles" means. I had a brand new 79B which, at 85 mph on the Autobahn, felt somewhat unstable. As if the body was lifting at speed and was not as stable. My 79 LE, with is spoiler, does not demonstrate this. Thus, a spoiler, as Stan mentions, seems to be an excellent investment from the standpoint of high speed stability.

Tire pressures, as has been noted, are an important factory. Original recommendations were for bias ply tires and early radial tires. I find that my cars handle better, and are more stable, with higher than recommended tire pressures.

All tires are not equal, even within the same brand. The local tire store recommended a Michelin tire for my wife's Mustang which caused it to handle very poorly. I contacted Michelin who informed me that the recommended tire was not suitable for a car that light. They recommended another tire in their line which performed in an excellent fashion. The car went from feeling unstable at 65 mph to being rock solid at speeds significantly in excess of that. So, check with your tire's manufacturer to see if they recommend the use of your tire on an MGB.

Rough roads will always be a problem in a sports car. Modern cars, especially the ones having dynamic stability control, adjust the suspension to take into account the quality of the road surface. Our cars do not have that capability and the increasingly poor quality of modern roads becomes more obvious because of it.

Les
Les Bengtson

Mark-
If you'll post your Email address, I'll send you something of about 35 pages that I wrote on the subject of handling and its related issues.
Steve S.

Steve S - I would love to have a copy of the handling document if you would be so gracious. My email is vesterback@shaw.ca - thanks in advance.

Mark - could "nibbling" mean alittle bit of wandering? Could the front alignment be somewhat off, particularly toed out? I seem to remember my alignment being different after installing V8 bushings and renewing the upper and lower bushings in my front suspension, causing the car to seem to want to wander.

Erick
Erick Vesterback

Hi Mark,
I'm back in San Diego from Arizona now... and the interstates here are not good road surfaces to drive on...because the surface is concrete that has been scraped to make grooves as you mention. I experience wobbles on interstate 5 as a result of the road more than the suspension.. I have rubber bushings which may absorb slightly better than poly. On a good road the front end is stable.
jjralston


First, congratulations on completing your engine swap. What a nice job you've done!!!

Everyone, check this one out: http://www.britishv8.org/MG/MarkMallaby.htm

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Now, at speeds of 85mph and up, I think you need to seriously think about an air dam. I'm certain you will notice a difference at those speeds.

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Peter wrote: "Put in the biggest antisway bar at the front you can get."

The stock front antisway bar is too thin for my tastes too... although if you stiffen up the front a LOT you'll probably also want to stiffen up the rear also to keep the car close to neutral in terms of understeer/oversteer.

---

Erick wrote: "Could the front alignment be somewhat off, particularly toed out?"

IMHO, you should check this first. If it's toed out, things will get scary at high speeds. Normally, a little toe-in helps a car feel more stable at speed - but I found with my MGB that a very little goes a long way! When I carefully reset my static toe-in to just 1/16" it made my MGB feel a lot more stable.
Curtis

Gents,

Thanks for all the input. I will check the toe in. Once I get to about 90 the front lifts and reminds one to slow down a bit. The tyres are Michilin Energy 185/70 x 14. I am interested in modifing the front end using telescoping shocks and such. More modern suspensions have great handling and good compliance I want both but are to cheap to buy the Hawk front end.
M Mallaby

Steve, I would love the information. e-mail is mmallaby@san.rr.com

Thanks!
M Mallaby

Some very good points here, and all are things that could be causing the problem you're describing.

I've experienced a similar problem as you're describing with my 75. I've experienced the very light front end as well as a lot of vibration in the front wheels and some shaking with the steering wheel.

The car became much more stable with the addition of the front air dam, but this didn't solve the vibration problem up front... shocks were redone and it got a little better. My alignment is good and my steering rack is tight.

The thing that I found made the biggest difference in reducing vibration on the highway had to do with the rostyle wheels. They're difficult to balance right when not on the car. The best way to get them done is while they're on the car.

I installed alloy wheels not too long ago and the problem's gone away. I've attributed the problem to some not-so-true and unbalanced wheels. If you can find a place that can ballance the tires while mounted on the vehicle, then try that first.
Dave Ryzuk

Hi Mark

I am experiencing similar with my car and have just taken the plunge and ordered the Costello front and rear suspension conversion. Had a go in the demonstrator and thought that I was in a Subaru it was so good. Amazing grip but funnily enough softer sprung than my car is at the moment, so much more comfortable on long journeys!

Give them a call and they will send you the info on the kits if of interest.

http://www.mgcars.org.uk/frontline/
Ed Braclik

Mark,

i had this problem on my V8 too and set the wheel bearings as detailed in the Leyland workshop manual. Afterwards everything was O.K.
1973 BGT V8 Rover SD1, LT 77 Gearbox, MG C 3.3 Rearend, uprated lever arm shocks and handling kit at the front, Spax at the rear set to position 2, 175/80 HR 14 tyres on Reliant Scimitar GTE rims (5.5")

Ralph
Ralph

Mark,
I would go with Dave's guess.
My '73 B got a litle wild and uncomfortable at about 70MPH. I had the tires speed balanced on the car and they never really settled down. I put a set of superlites on the car and it drives like a new car.
No gut feelings to need to slow down now, except for the the high RPMs.

Mark Miller
Mark Miller

Mark,
Forgot to say, check your rostyle wheel and see if the are not warped. Lay a flat board on the rim and you may see a little "daylight" between the rim and the board. Mine became a little warped over the years.

Mark
Mark Miller

This thread was discussed between 13/07/2007 and 26/07/2007

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