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MGB Kingpin conversion: anyone have camber problems?

Posted by Duncan 
bills Avatar
Bill Spohn
W. Vancouver, BC, Canada   can

Duncan, I set up my Jamaican on a proper laser alignment rack and measured the heck out of everything. I don't have the figures here, but the camber was at most -2 deg., which will certainly wear the inside of the tires first, but will work much better than stock for aggressive driving. These cars don't typically get driven enough in a given period to wear the tires out before they tires are theoretically stale dated anyway (5 years is the figure we see bruited about though I'm sure we all keep them much longer) so I thought that handling for a bit faster wear was a fair trade off. You may feel differently, in which case the suggestion of offset upper MGB trunion bushes may solve it for you.



Bill Spohn www.rhodo.citymax.com/carstuff.html
1958 MGA Twincam (race car (170 bhp)),1962 MGA Deluxe Coupe (98 bhp)
1969 MGC roadster (175 bhp), 1957 Jamaican MGA (200 bhp)
1965 Jensen CV8 (375 bhp), 1971 Jensen Interceptor (350 bhp)
1969 Lamborghini Islero S (350 bhp), 1988 Fiero GT turbo (300 bhp)
2009 Pontiac Solstice GXP Coupe (350 bhp)
West Vancouver BC

dipstick Avatar
Kenny Snyder
La Center, Washington, USA   usa

Hi Duncan,

My experience with MGA/MGB camber is different than Bill's. Granted, my experience is not autocross, just street and left/right track road racing with both SCCA Production (slicks) and Vintage (DOT) MGs.

I use zero camber on the street and racing cars. Having done hundreds of tire temperature tests (outside/center/inside) my opinion is that any negative camber on the MGA/MGB will heat up the inside of the tire and likewise cool off the outside of the tire. Increasing the inside tire temperature results in a smaller tire contact patch as well as uneven tire wear.

Yes, there is a "feel good" thing with negative camber as the chassis turns in so nicely in slow turns (street/autocross), but at speed the same car will push (oversteer) like a big dog. My opinion is that even one degree of negative camber is not acceptable.



Be safe out there.
Kenny


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bills Avatar
Bill Spohn
W. Vancouver, BC, Canada   can

Ken, as it happens I also run pretty close to zero camber on the race car.

I run negative camber on the street (and in the long ago days, slalom) cars for exactly the reasons you state.

Oddly enough I set my Solstice up with significant negative camber and on that chassis it works very weel at high speeds and has no negative effect at lower speeds.

On another similar issue, how many people have we seen that lower their street cars for that racy look while totally ignoring the bump steer it can introduce? I tend to stick to normal ride height - scraping over speed bumps can get tedious.



Bill Spohn www.rhodo.citymax.com/carstuff.html
1958 MGA Twincam (race car (170 bhp)),1962 MGA Deluxe Coupe (98 bhp)
1969 MGC roadster (175 bhp), 1957 Jamaican MGA (200 bhp)
1965 Jensen CV8 (375 bhp), 1971 Jensen Interceptor (350 bhp)
1969 Lamborghini Islero S (350 bhp), 1988 Fiero GT turbo (300 bhp)
2009 Pontiac Solstice GXP Coupe (350 bhp)
West Vancouver BC

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mgaex189 Avatar
Giovanni Delicio
Obrigheim, Rheinpfalz, Germany   deu
1955 MG MGA 1500 "C2"
1955 MG MGA 1500 "C1"
1955 MG MGA 1500
1960 MG MGA 1600 Coupe
1961 MG MGA MkII   → more

there are a lot of differences peculiar to the very, very early cars, like mine,

Duncan,

HOW early is your car ? 1955?

You may send me a PM.

Regards

Giovanni

dipstick Avatar
Kenny Snyder
La Center, Washington, USA   usa

Hi Bill,

I meant to say understeer, not oversteer. I was multi-tasking; pretending to be listening to my wife, eating a sandwich, and composing the post. I did successfully eat the sandwich.

My Z32 300ZX has a ton of camber (front & rear), yet the tire temperatures are equal across the fronts and rears, but that is a strut suspension.

"lower their street cars for that racy look while totally ignoring the bump steer it can introduce?"

The MGB red vintage was on the deck, the lower control arms pointing into the sky, and long negative camber lower control arms w/oval outer king pin bolt holes. I was getting three degrees negative camber, and on track 40+ more degrees temp. on the insides. The bump moved the dial indicator so fast I had to have someone else turn the jack handle. The long lower control arms went onto the mill and the oval holes were slotted, then back onto the chassis with heavy duty washers on the outside, and with longer bolts. Next the zero camber was established and the washers were, in place, tack welded to the control arms. Then back off to weld the washers and fill the slots.

After much shimming I was able to eliminate some of the bump, but not enough, not with those spindles.

I don't lower my street MGs, except for normal spring sag. There are too many rough roads and speed bumps around here for that.



Be safe out there.
Kenny

barneymg Avatar
Barney Gaylord
Naperville, Illinois, USA   usa
1958 MG MGA "MGA With An Attitude"

A and B lower A-arms are same parts. A and B shock arms are same length. A and B shock bodies are both symmetrical so the body can be turned around without changing camber. Offset distance from kingpin to top trunnion bolt is different, positioning the top of the kingpin farther inboard on the MGB. But the MGB wheel still stands straight up with zero camber. Does that mean there is greater kingpin angle with the MGB knuckle (in the standard MGB)? Or is the shock mounted farther outboard on the MGB?



Barney Gaylord - 1958 MGA with an attitude - http://MGAguru.com

colynf Avatar
Colyn Firth
South Yorkshire, UK   gbr

Duncan

Dont go for negative camber if you intend to do any really high speed cornering (especially if you have the suspension lowered a little like mine is)
The negative camber makes the steering amazingly sharp on the slower very tight bends and it is great fun BUT at high speeds on the longer curves the rear wheels may easily break away from you.
The problem is that the steering becomes so sensitive that when you try to correct the slide the car just snaps the other way.
Even driving on the freeways was difficult as the car would need constant steering to keep it in a straight line.
I have been very very close to losing the car at speeds over 60 -70 mph on fast corners and have just taken the neg camber lower suspension arms off and replaced them with standard ones.

The car has been transformed and is now a delight to drive at all speeds.

I wish I had done it years ago.

Colyn

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bills Avatar
Bill Spohn
W. Vancouver, BC, Canada   can

In reply to # 2301742 by colynf Duncan

Dont go for negative camber if you intend to do any really high speed cornering (especially if you have the suspension lowered a little like mine is)

Colyn, I have to think that at least some of your issues come from enhanced bump steer from lowering as my street coupe is neither twitchy nor has it any problem holding a line in a high speed corner and is easy to catch if it starts to lose adhesion. Same with the Jamaican, although I don't recall submitting it to really hard cornering above maybe 80 mph. Both cars track stright - you can take your hands off the wheel and no veering due to road surface - that really sounds like severe bump steer to me.



Bill Spohn www.rhodo.citymax.com/carstuff.html
1958 MGA Twincam (race car (170 bhp)),1962 MGA Deluxe Coupe (98 bhp)
1969 MGC roadster (175 bhp), 1957 Jamaican MGA (200 bhp)
1965 Jensen CV8 (375 bhp), 1971 Jensen Interceptor (350 bhp)
1969 Lamborghini Islero S (350 bhp), 1988 Fiero GT turbo (300 bhp)
2009 Pontiac Solstice GXP Coupe (350 bhp)
West Vancouver BC

colynf Avatar
Colyn Firth
South Yorkshire, UK   gbr

Thanks Bill

I think you are correct about the lowered suspension issue when combined with negative camber, the bump steer was vicious and nearly had me off the road on many occasions.

I put up with how the car handled for many years as the turn-in on tight country lanes was just sensational. But on a recent MGA Register tour I had the car sideways almost from lock to lock when I hit a bump on a long bend at about 70mph. My wife wasn`t very impressed!

So I ditched the negative camber lower arms and fitted standard ones and the car was transformed even though I still retained the lowered springs.

It now tracks straight and corners beautifully and I no longer have to take a deep breath and take a step into the unknown each time I drive into a fast bend!

The benefits from the lowered suspension are few:- slightly better cornering due to reduced body roll and it looks great (to me anyway!)

The disadvantages:- a much harder ride and reduced ground clearance.

I have found that the improved cornering can only be used on a very smooth road surface, a race track for instance. On bumpier road surfaces, the car and the driver get rattled about a fair bit and I find it hard to keep up with MGAs with standard suspension whose cars ride the bumps much easier. So I may well fit standard springs sometime in the future

So to me, the conclusion seems to be:- Dont fit lowered suspension and negative camber lower arms at the same time, just chose one or the other!

Colyn

bills Avatar
Bill Spohn
W. Vancouver, BC, Canada   can

I agree with your conclusion,. Colyn!

It is annoying that Moss doesn't offer proper stiffer front springs (something that works well on the MGs). They went the cheap way - chop a coil off the stock springs, have their manufacturer make them shorter so they can claim they are stiffer (which si true, of course) but using the same wire diameter, instead of just winding them from a different diameter of wire. They are essentially making the height decision for you - want stiff springs, you have to lower the car.

I have used their springs as it is cheaper than having custom wound springs made, and then I machined up some spacers for the top of them to get back to stock ride height.



Bill Spohn www.rhodo.citymax.com/carstuff.html
1958 MGA Twincam (race car (170 bhp)),1962 MGA Deluxe Coupe (98 bhp)
1969 MGC roadster (175 bhp), 1957 Jamaican MGA (200 bhp)
1965 Jensen CV8 (375 bhp), 1971 Jensen Interceptor (350 bhp)
1969 Lamborghini Islero S (350 bhp), 1988 Fiero GT turbo (300 bhp)
2009 Pontiac Solstice GXP Coupe (350 bhp)
West Vancouver BC


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dipstick Avatar
Kenny Snyder
La Center, Washington, USA   usa

Our ex Steve Beckham MGB E/P racecar (Rainbow), destroyed at Willow Springs, had adjustable spring pans. The spring depression had been cut out and fitted with a male threaded ring, and the pan fitted with a female threaded ring. From under the assembly in the center was a bar with a 1/2" square hole for fitting a breaker bar. I can't find a picture of that setup.



Be safe out there.
Kenny

bills Avatar
Bill Spohn
W. Vancouver, BC, Canada   can

I've seen that too, Kenny, but it has always struck me as being something you'd fit, set up for the tracks you run and then never adjust again. Might as well just set the suspension at an average height and forget about it. Seems over complicated.



Bill Spohn www.rhodo.citymax.com/carstuff.html
1958 MGA Twincam (race car (170 bhp)),1962 MGA Deluxe Coupe (98 bhp)
1969 MGC roadster (175 bhp), 1957 Jamaican MGA (200 bhp)
1965 Jensen CV8 (375 bhp), 1971 Jensen Interceptor (350 bhp)
1969 Lamborghini Islero S (350 bhp), 1988 Fiero GT turbo (300 bhp)
2009 Pontiac Solstice GXP Coupe (350 bhp)
West Vancouver BC

dipstick Avatar
Kenny Snyder
La Center, Washington, USA   usa

Bill,

Oh yeah, way overkill and heavier, plus the threads got full of grit. The setup did serve in a couple of ways: Patricia was/is considerably lighter so we could quickly drop and equalize the ride height for her, and for those long rainy weekends with the dog-bone rains on the entire time the front could be lowered to compensate for the increased tire height.



Be safe out there.
Kenny

bills Avatar
Bill Spohn
W. Vancouver, BC, Canada   can

In reply to # 2302887 by dipstick Bill,

Oh yeah, way overkill and heavier, plus the threads got full of grit. The setup did serve in a couple of ways: Patricia was/is considerably lighter so we could quickly drop and equalize the ride height for her,

Ah - I always wondered why she was often faster - that must have been it! devil smiley



(Just kidding, although I do recall her sometimes being faster, which I always attributed to her being a smoother driver than us guys usually are.)



Bill Spohn www.rhodo.citymax.com/carstuff.html
1958 MGA Twincam (race car (170 bhp)),1962 MGA Deluxe Coupe (98 bhp)
1969 MGC roadster (175 bhp), 1957 Jamaican MGA (200 bhp)
1965 Jensen CV8 (375 bhp), 1971 Jensen Interceptor (350 bhp)
1969 Lamborghini Islero S (350 bhp), 1988 Fiero GT turbo (300 bhp)
2009 Pontiac Solstice GXP Coupe (350 bhp)
West Vancouver BC

Duncan Avatar
Duncan Cowen
Delta, Vancouver, Canada   can

In reply to # 2301000 by PeterC ..there IS a difference of roughly half a bolt diameter where the MGA is farther outboard than the B.

As I said to Duncan, I think a set of offset camber adjusting bushings such as Moss sells (282-308) would be sufficient to adjust the camber to either dimension you would want.

Peter C

I had a look at the pic Moss provides of these bushings.



Reading the directions for installation clearly indicates that they replace "3d" in the image below, the rubber between the MGB shock arm and the top of the kingpin.



Interestingly, Moss gives camber suggestions in the text below that exploded view.

From a purely aesthetic point of view, I'm glad they're used at the top, because I think MGA front wheels "look" like they tuck into the wheelwells more than the rears do. Also, my lovely new wide tires rub on the swaybar as I approach full lock, so I'd prefer to pull the top of the kingpin out, rather than move the A-Arm in.

Can anyone comment on UHMW Polyethylene as a long term bushing material, as opposed to rubber or Polyurethane?

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