BritishV8 Forum

General Category => Steering, Suspension, & Brakes => Topic started by: J Man on December 25, 2012, 06:52:18 PM

Title: Negative camber lower control arms
Post by: J Man on December 25, 2012, 06:52:18 PM
I found someone selling a set of these. What would their purpose be? Advantages to running them? Would they cause wheel fitment issues? Thanks
Title: Re: Negative camber lower control arms
Post by: Jim Stabe on December 26, 2012, 10:17:54 AM
What do they fit? Post a picture
Title: Re: Negative camber lower control arms
Post by: BlownMGB-V8 on December 26, 2012, 12:10:35 PM
Might be helpful if you cut the springs to lower the car.

Jim
Title: Re: Negative camber lower control arms
Post by: mgb260 on December 26, 2012, 12:58:29 PM
They are about 1/8" longer than stock MGB lower arms and give about 2 degrees negative camber. Front tires will wear a little more inside. Help cornering a little.
Title: Re: Negative camber lower control arms
Post by: Moderator on December 26, 2012, 01:24:26 PM
Moss has sold these for MGB for as long as I can remember.

For the MGB, they look exactly like regular lower control arms - just slightly longer. (We're talking about just the two c-channels which bolt to either side of the spring pan. The spring pan doesn't change.)  

Yes, they alter cornering (for the better) but they also effect braking (slightly for the worse, at least in a straight line.)

What do they do exactly? In simplified terms... as the car's body tilts sideways while negotiating a turn, and as weight load shifts from the inside front tire's contact patch to the outside front tire, and as the outside suspension compresses, and as a function of the unequal length and non-parallel arrangement of upper versus lower control arms, the wheels and tires lean over a little bit. That's called "camber change." These arms change the starting point for that camber change behavior, and subsequently the ending point. Again, in very simplified terms... you'd like the outside tire to be perfectly perpendicular to the road at all times. That's not feasible. This product might help your tires achieve perpendicularity in hard turns.
Title: Re: Negative camber lower control arms
Post by: J Man on December 26, 2012, 08:23:08 PM
I guess I forgot to mention what vehicle these were for but you guys figured it out.

Would these be good for a daily street driven vehicle (or even needed) or more suited for a race application?
Title: Re: Negative camber lower control arms
Post by: MGBV8 on December 29, 2012, 09:51:25 AM
They are totally unnecessary (some would say undesirable) for a daily driver.

Disclaimer: I still run the stock lower A-arms on my street/autocross/track day MG.  It seems to holds its own just fine without the additional negative camber.
Title: Re: Negative camber lower control arms
Post by: ex-tyke on December 29, 2012, 10:06:05 PM
QuoteThey are totally unnecessary...

I dunno, Carl....the NASCAR boys take camber to the max.
Title: Re: Negative camber lower control arms
Post by: Moderator on December 29, 2012, 11:33:50 PM
In racecar set-up, one lap-time reduction strategy is to maximize exit speed from whatever corner comes immediately before the longest straight. How tight is that corner? How much banking? A racer might add or reduce static camber compared to the previous weekend's set-up to optimize that one corner's exit speed thus providing faster speed all the way down the main straight.

If the banking is different at Daytona than it is at Martinsville, for example, it makes sense that NASCAR boys probably adjust camber accordingly.

One screwy up thing about MGBs is that swapping control arms is a gross adjustment. I wish someone would offer stock-length control arms except with a nifty adjustment cam mechanism at one end to facilitate fine tuning. (But maybe the adjustment should be made at the upper end. No?)

Here's the important point:  a racecar can't be optimized for every corner on a road racing circuit, and a car certainly can't be optimized for every corner on real world roads. You have to choose a compromise setting. (I use stock lower control arms.)
Title: Re: Negative camber lower control arms
Post by: MGBV8 on December 30, 2012, 11:44:09 AM
Now Graham, somewhere in that sentence I did say daily driver.

QuoteI wish someone would offer stock-length control arms except with a nifty adjustment cam mechanism at one end to facilitate fine tuning.

Bill Guzman used to sell something like that.
Title: Re: Negative camber lower control arms
Post by: BlownMGB-V8 on December 31, 2012, 11:09:49 AM
So, maybe it would be helpful for something like a car that had been lowered by using shorter springs?

Jim
Title: Re: Negative camber lower control arms
Post by: Moderator on December 31, 2012, 12:55:56 PM
Helpful in what way?

The main negative side effect of lowering a car by fitting shorter or shortened springs is that it typically shifts the operating range of the suspension from a zone of relatively little bump steer into one where bump steer is more pronounced. Camber shouldn't significantly effect bump steer.

Why do alignment shops check and adjust camber on other cars besides MGB? My perception is that suspensions and frames tend to get tweaked on potholes and/or in minor accidents. I suspect a more fully adjustable suspension might be brought back to factory spec with fewer replaced parts.
Title: Re: Negative camber lower control arms
Post by: BlownMGB-V8 on January 01, 2013, 12:58:23 PM
I was thinking that the camber change at static ride height might be brought back closer to spec that way. Since the bottom pulls in under compression a longer arm would move it back out. But it might be too much.

Anyway, drop spindles would be a better way to lower the car.

Jim
Title: Re: Negative camber lower control arms
Post by: roverman on January 02, 2013, 12:21:51 PM
I suspect a lot of oem designs have "some" degree of bump steer, much like different akerman amounts. Perhaps a good place to start is minimizing the bump steer ? Why not run air bags ? You get static ride height where you want it ,and tunable rising, spring rates. Seems like moving the uca, inner pivots, up/down should help in fine tuning the camber curve ?  Chees, roverman.
Title: Re: Negative camber lower control arms
Post by: BlownMGB-V8 on January 02, 2013, 05:21:55 PM
About four of us have tried air bags with varying success in the MGB. The biggest problem is finding a 4" diameter bag which nobody seems to make. The 4-1/2" ones are a little tight and may chafe.

Jim
Title: Re: Negative camber lower control arms, bags ?
Post by: roverman on January 03, 2013, 09:08:13 PM
Jim and clan, might want to peep, "AirBaggit.com". At least 2 lengths of 4" dia. bags,(double and triple convolute), rated at 1k lbs. ea. At least 2 kinds of 4" dia air shocks rated at 1k lbs ea. Not an endorsement. I bought my "Healey" bags/etc., from them. Good Luck, roverman.
Title: Re: Negative camber lower control arms
Post by: BlownMGB-V8 on January 04, 2013, 09:48:26 AM
I know it says 4" on the description but they really are closer to 4-1/2. With those bags it takes a fair amount of work and even more good luck to get adequate clearance we've found. If they were just 1/4" smaller it would be ideal.

Jim
Title: Re: Negative camber lower control arms, bags ?
Post by: roverman on January 04, 2013, 01:38:50 PM
Clan, First bag listed, on their site #800, 3.5" dia. 150 max psi, 1,500 lbs/axle, 6"-10" height, cost $39. ea.  Onward, roverman.
Title: Re: Negative camber lower control arms
Post by: BlownMGB-V8 on January 04, 2013, 03:39:35 PM
Haven't looked at that one, almost certain to be too long. Might buy one or two and try them. I already have too many "spares" lying around, it's somebody else's turn.

Jim
Title: Re: Negative camber lower control arms
Post by: MGBV8 on January 04, 2013, 08:29:45 PM
Bump steer? I think too much is made of the little bit of bump steer caused by lowering an MGB with shorter springs.
Title: Re: Negative camber lower control arms
Post by: J Man on January 04, 2013, 09:12:23 PM
Since this has turned into an air ride conversation, thins could be an option.

http://www.arnottairsuspension.com/
Title: Re: Negative camber lower control arms
Post by: BlownMGB-V8 on January 05, 2013, 12:20:50 PM
Bike shocks?
Title: Re: Negative camber lower control arms
Post by: J Man on January 06, 2013, 01:53:35 AM
They make a few different options for various weights. It has been a while since I looked at the site, that is why I said it could be an option. The ones I do remember seeing were meant to go in at replacements for coil overs.