Drop Spindle Discussion

[MaurizioF]

Quote:

Originally Posted by BigSwede We're (at least I am) talking about the modified steering arm as seen on the above modified spindles/uprights. I'm trying to get an answer to how he came to that position of the joint, at the moment Alfar7 is either playing dumb because he doesn't want to answer or he did it by gut feeling and haven't got a clue what really happens.

[junglejustice]

Quote:

Originally Posted by BigSwede ...at the moment Alfar7 is either playing dumb because he doesn't want to answer or he did it by gut feeling and haven't got a clue what really happens.

[Alfar7]

Sorry to have taken so long to reply, but I have been away racing.

As to why & how I modify the spindles is a result of a few years experience building race chassis not just modifying Alfa`s for racing as I have done since 1969. FYI, I am totally comfortable with my knowledge of suspension design.
The need to share how I determine the steering arm position and the design of my fixture is something I don`t need to do, along with the pre-welding process, alloys used and heat treating process. Of the many spindles I`ve modified since the first 101`s & 105`s in 1969, I`ve not had a failure or complaint with it`s function.
I share quite a lot with this forum, and the Alfaracing list, and most find it useful. Some things you are just not going to have shared . Sorry......

[SPORTSCAR.NET]

i've had very good luck using spindles from a '92 ranger (yes, i know, a travesty, but they've been entirely bulletproof). they require very minor modification to fit, but it might be well worth trying on your alfas, especially seeing how cheap they are.

[Hit an Apex]

Quote:

Originally Posted by SPORTSCAR.NET i've had very good luck using spindles from a '92 ranger (yes, i know, a travesty, but they've been entirely bulletproof). they require very minor modification to fit, but it might be well worth trying on your alfas, especially seeing how cheap they are.

[BigSwede]

Quote:

Originally Posted by Alfar7 Sorry to have taken so long to reply, but I have been away racing.

[Alfar7]

Quote:

As far as I'm concerned, if you're not comfortable with sharing the why and howcome it's pretty pointless to show pictures of the result. But maybe that's just me?

[BigSwede]

oh, no. Now I'll never find out how to do that heavy modification. :P

I have my car sorted, without adding a pound of steel to the unsprung mass, I was thinking that maybe the other guys was interested of some actual data instead of trying to copy something from pictures.

[alfaspence]

This may seem ignorant but (and maybe i should have read the whole thread) whats the idea of this mod? my car is lowered 30mm, std bushs/ shox (for now) running 15" compo mo's...
i have nothing fouling suspension-wise at the front and virtually no under steer (rear does the work)
wot gives

[Echo Leader]

Richard, are you not sharing the technical specs because you sell these and don't want people simply copying vs. potentially buying from you?

And if you do sell them, do you have a set of parameters you always build to (obviously a bit different with wheel size) or do you build each set with the buyer's ride height in mind? oh....and how much $$$?

Thanks!

[Alfar7]

[QUOTEThis may seem ignorant but (and maybe i should have read the whole thread) whats the idea of this mod? my car is lowered 30mm, std bushs/ shox (for now) running 15" compo mo's...
i have nothing fouling suspension-wise at the front and virtually no under steer (rear does the work)
wot gives
][/quote]

What about bump steer?

Look at the angles on your upper & lower A arms.
With the lower arm angled up you have lost the benefit of the unequal length A arm design, and as well, lost wheel travel.

The proper position for the lower arm is parallel to the track/road surface.
By lowering the car using dropped spindles there are at least three benefits.
One, simply is no loss of wheel travel & compliancy.

Another ,key benefit, is a longer(taller) spindle carrier(upright). (remember the knuckle risers on early 101 & 105 racecars?)
This length (added to the bottom under the spindle) increases the angle of the upper "A" arms when the lower arm is still level, which results in more camber change per degree of wheel movement.

In rebound (bump or upward movement) which on track is caused simply by body roll entering and through turns, there is a significant increase in negative camber. Enough, that rather than then having "positive camber" and loss of the contact patch between the tire & pavement as with the stock design, You actually have enough negative camber gain, to not just offset the body roll`s resulting movement towards "positive camber" but have a slight increase in "negative camber" to give the tire a better footprint on the pavement.
As well, on the other side of the car, rather than the suspension leaving the inside tire at negative camber, the droop (downward movement) of the suspension results in the upper arms moving the top of the upright farther out, moving the tire into a "positive camber" position increasing that tire`s bite as well.

When a car is incorrectly dropped so that both upper AND lower arms are angled upward every movement of the suspension moves the tire in or out severly causing major bump steer. Under braking or bump, you get "toe out", exactly what you do not want. Under droop, you get "toe in" . On the track all this results in a car with unstable conditions under braking, and unresponsive turn in.

With dropped & longer spindles , with the steering arms returned to the correct position relative to the steering rack, and with some increase in the Ackernan angles (which I do when modifying the spindles & arms), you can set up the car with less overall negative camber, with "0" toe in or out, resulting in less drag, less tire wear, and still result with correct camber footprints under cornering on both sides of the front. As well, the Ackerman changes I make result in increased "toe out" when the wheel is turned off center giving better "turn in" response, when cornering.

Please contact me off thread about having these modifications made & I will be happy to respond.

By the way,I tried to make this simple enough for JJ & BS (who`s avatar gives us a clue), but it probably won`t be enough. Useless postings
guys!

[junglejustice]

Quote:

Originally Posted by Alfar7 [color="DarkSlateGray"] In rebound (bump or upward movement) which on track is caused simply by body roll entering and through turns, there is a significant increase in negative camber. Enough, that rather than then having "positive camber" and loss of the contact patch between the tire & pavement as with the stock design, You actually have enough negative camber gain, to not just offset the body roll`s resulting movement towards "positive camber" but have a slight increase in "negative camber" to give the tire a better footprint on the pavement.

[Echo Leader]

JJ, are those kg/cm numbers? And do you know the motion ratio of the GTV6? I've got some numbers I'm working with and I want to be able to develop wheel rate numbers for the available RSR spring rates. Thanks!

Still JJ, doesn't that route us right back to the concept, that was being heavily discussed on alfagtv6.com/bb, that you could achieve the same roll stiffness with less wheel rate (less spring and roll bar) by having the geometry of a lowered GTV6 or Milano itself oriented so as to discourage roll? The RSR kit seems to do an excellent job of eliminating roll through increased spring rates and a massive 30mm anti-roll bar thus these issues still exist in the suspension but are supressed...right? Why not address the issues with the drop spindle and then select spring rates and anti-roll bar thicknesses?

Hopefully that makes sense, I'm just learning...