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Effects of Lowering the Front End

vette

Darth Vader
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I didn't want to steal the thread about the driving lights where we started to talk about lowering the body.
So I am just trying to visualize and figure out what occurs when you lower the front end by allowing the coil spring to be seated lower than the lower control arm. this being done by use of the spacers to lower the seat pan. I've attached a drawing. Seems to me that at the least you are lowering the riding height of the shock which of course lowers its pivot. With the same dimensions of all the pieces in triangulation this seem to me to pull the upper trunion towards the centerline of the car. This would be moving the camber in a negative direction. But since the Healeys were built with a slight positive camber, this small negative movement my be trivial to the handling of the car.
 

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RAC68

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Hi John,

Thank you for responding to my info request on the Driving Lights thread. The picture provided seems to show the installation of (4) 1/2" spacers around the bottom plate mounting bolts which effectively lower the plate and the body. Are spacers all that is needed? I have some thick walled aluminum pipe that I can cut in 1/2" pieces for installation as the pictures show. Am I missing something needed that I can't see?

I also appreciate the lowering will make the engine pan vulnerable and have already experienced slicing it about 40 years ago when speeding down a NYC street and trying to straddle what looked like a big hole and turned out to be a raised sew plate. If I understand, you used nuts that provide 1/2" spacing. If 3/4" spacers produced a 1" body drop, how much did your 1/2" spacer drop the body?

Ray(64BJ8P1)
 

Drone Dog

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vette
i have mild competition springs in my TR6 which were a 1/2" shorter than stock. So i added 1/2" spacers when i installed. after realizing that the competition springs were shorter but stiffer, they did not need a spacer. So i took them out after i had already had the alignment done.

in the rear there was a noticeable increase in negative camber. so i put them back in. but in the front nothing noticeable to the naked eye. i think over that short distance change the upper arms keep the spindle virtually the same angle.
 

RAC68

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Hi Vette,

I agree. Since the relative positioning of the upper and lower pivots remains the same as this is maintained by having a static shock tower mounting as well as no change is the bottom "A" arm pivots. However, since the body drop is due to reducing spring resistance, the axel/wheels-center height remaine unchanged relative to the ground. As a result, the wheels would angle inward at the top resulting in adding Negative Camber.

Ray(64BJ8P1)
 
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vette

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Hi Vette,

I agree. Since the relative positioning of the upper and lower pivots remains the same as this is maintained by having a static shock tower mounting as well as no change is the bottom "A" arm pivots. However, since the body drop is due to reducing spring resistance, the axel/wheels-center height remaine unchanged relative to the ground. As a result, the wheels would angle inward at the top resulting in adding Negative Camber.

Ray(64BJ8P1)

Ray, are you saying that the geometry will keep the camber unchanged but since the spring is softer the articulation of the suspension during spring compression will allow the swivel pin to lean inward to a larger degree than normal.
 

steveg

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I look at the geometry like this:
The car sits on the springs, which sit on the spring pans. The taller your spacers between the spring pans and the A-arms, the more the A-arms are rotated upward relative to the spring pans.

My car, with 180 tires - the suspension A-arms are just below horizontal, say, 43 minutes past the hour. If I inserted 1/2" spacers, they would be around 45 minutes or horizontal. That would be as much camber as I could get without modifying the upper trunnion or shock bolt position. If I installed 1" spacers, the camber might be back to the stock position as the A-arms would be at the 47 minutes position.

Having said that, the amount the lower trunnion could be moved outward by this method looks like about 1/32" - 1/16".

Isn't the whole lowering thing about 1) lowering the center of gravity thus allowing greater cornering g-force and 2) a cool racecar-looking stance.
 
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vette

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Steve, IMO if the control arms, the lower one or the upper one, which is the shock arm, if they move at all from there original, stock positioning then you will have changed camber. They swing in an arc. Obviously they will move together since they are connected together via the swivel pin. As the suspension is moved thru its movement the camber is changing all the time. Camber (change) is the change of the angle of the wheel relative to horizontal.
 

Randy_Gay

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Mine is lowered about 1/2" and looks a lot better - the radius point for the wheel is centered on the fender arch. If you go too low the caster may become affected. I also have the rear set centered on the fender arch.
 

RAC68

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Hi All,

Vette, Yes. The effect of lowering the spring pan will be to provide less constraint to the spring and allow the suspension to move a little more freely. Since the geometry has not changed with respect that all arms and relationships are maintained, the change in camber is as a result of the more fluid swing and, as you have stated, the increase in ark. Will it produce a substantial change? I don't think so as Changing the geometry by moving the shock mount location or "A" frame pivot locations would definitely change the camber. Even if you change any of the lengths (Shock arms, "A" frame arms, trunnion length or even the distance between upper and lower pivot points) could also have a definite effect and change the camber … among other things.

Please don't misunderstand, lowering the body may not produce a significant camber change but could cause improvements in maneuverability at a small or no cost. However, lowering the suspension and making it softer would greatly increase the risk of bottoming and smashing the oil pan. So, is the change in looks and maneuverability worth the risk? I am not so sure.

Ray(64BJ8P1)
 

John Turney

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Hi John,

Thank you for responding to my info request on the Driving Lights thread. The picture provided seems to show the installation of (4) 1/2" spacers around the bottom plate mounting bolts which effectively lower the plate and the body. Are spacers all that is needed? I have some thick walled aluminum pipe that I can cut in 1/2" pieces for installation as the pictures show. Am I missing something needed that I can't see?

I also appreciate the lowering will make the engine pan vulnerable and have already experienced slicing it about 40 years ago when speeding down a NYC street and trying to straddle what looked like a big hole and turned out to be a raised sew plate. If I understand, you used nuts that provide 1/2" spacing. If 3/4" spacers produced a 1" body drop, how much did your 1/2" spacer drop the body?

Ray(64BJ8P1)

Hi Ray,

Yes, spacers are all that is needed, although you could also put spacers under the bump stops (#16 on the Moss page) to counteract the lowering of the spring pan.

The photo showed the 3/4" spacers from Dennis Welch. The 1/2" nuts raised the front about 3/8" from what it was with the 3/4" spacers; a drop of 5/8" from original. I used the nuts as they were easy to replace the DW spacers, I had them and strength isn't an issue.

John
 

John Turney

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I recall that the camber becomes more negative on an Austin Healey as the car is lowered. That is not always the case. It depends on the the relative positions of the four pivot axes (upper A-arm inner and outer, and lower a-arm inner and outer). On a Healey (pre-Austin) IIRC the front suspension uses trailing arms, so camber is not affected.
 

Drone Dog

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IIRC the healey comes from the factory with a 1* positive camber. would not adjusting some negative camber in to the front end be better for the radial tires we run?
 

RAC68

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Hi Steve,
Observing race versions of sports cars on the track: they're as low as possible and look to have very stiff springs.

I would expect if I were racing and lowered my car for better agility, I would not want to have a softer front suspension. I would probably lower the car height through a more extensive modification to the suspension and not just lower the spring pan. Such things as camber modification through the addition of adjustable shock mounts and other changes, many of which I am not aware are even available, would probably be in use.

It would be nice to hear of the extent of suspension modification form members using their Healey for racing that would be enlightening and provide a more definitive and experiential perspective and far better then my suppositions can provide.

Ray(64BJ8P1)
 

HealeyRick

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Hi Steve,


It would be nice to hear of the extent of suspension modification form members using their Healey for racing that would be enlightening and provide a more definitive and experiential perspective and far better then my suppositions can provide.

Ray(64BJ8P1)

Hi Ray,

This is a great thread from Healey racers: https://www.ahexp.com/phorum/read.php?8,5181 I haven't looked through the whole thing but expect the answer may be there somewhere. Ray, if it's not, you could ask since you are already a member.
 

RAC68

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Thanks Rick,

Great alternative if no one from this Forum responds or doesn't have the knowledge. But I would expect someone from here knows.

Thanks again,
Ray(64BJ8P1)
 

RAC68

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Rick,

Looking at your picture, I noticed that your Healey looks like it had been lowered. How did you do it?

Ray(64BJ8P1)
 

HealeyRick

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Rick,

Looking at your picture, I noticed that your Healey looks like it had been lowered. How did you do it?

Ray(64BJ8P1)

Ray,

After I installed the V8, the front end came up quite a bit due to the reduced weight. I brought it back down in the traditional backyard hot-rodder manner by replacing the spring pan bolts with longer Grade 8 ones and inserting two Grade 8 nuts on each bolt between the spring pan and wishbone.
 
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vette

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Ray,

After I installed the V8, the front end came up quite a bit due to the reduced weight. I brought it back down in the traditional backyard hot-rodder manner by replacing the spring pan bolts with longer Grade 8 ones and inserting two Grade 8 nuts on each bolt between the spring pan and wishbone.

Ah Ha, sneaky devil are ya. And you weren't going to tell anyone either, huh. :smile:

Bye the way, any noticeable change in steering or in wear on the tires ?
 
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Hi All,

Please don't misunderstand, lowering the body may not produce a significant camber change but could cause improvements in maneuverability at a small or no cost. However, lowering the suspension and making it softer would greatly increase the risk of bottoming and smashing the oil pan. So, is the change in looks and maneuverability worth the risk? I am not so sure. Ray(64BJ8P1)

Ray, I agree with your proposition and considering that Austin Healeys are already troublesomely low I'm not sure of the benefit either. But they do look cool planted way down and if I were to be a serious competitor I would probably want to lower it in some way. I am also pretty sure that I would want stiffer springs. How about if we just cut a coil out of the original springs and lower it that way. That would be how a REAL hot rodder would do it. Not this fancy nut and long bolt approach. :smile:
 
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