Would dropped spindles help handling?

[HP2]

Wow, I completely forgot about moparchat.. Dang!

I also have a Hollander book somewhere out in the garage. Mebee I'll have to go digging and see if I can find it.

[brads70]

Wow, I completely forgot about moparchat.. Dang!

I also have a Hollander book somewhere out in the garage. Mebee I'll have to go digging and see if I can find it.

Ya I had never heard of them! I just stumbled across them looking for specs on the C-body spindle! I like the circle track crowd because they are always on a budget and very resourceful....for the most part! They know how to get it done with stock parts, ....well the older ones do anyhow? The younger ones seem to want to race outta their wallets and not use their brains?

[72bluNblu]

I am confused as to why people think the dropped spindles are required to properly lower a car. To lower an ABE body is not rocket science and you can only lower the chassis so far before it hits every object in the road...

( Ditto)I agree with what HP2 said to you! Some members have found that with BIGGER ( over 1"?) T-bars there is not enough adjustment in the stock set up to lower the car

I wish I could have lowered my car with just my torsion bar adjusters!!! Normally being able to lower the car with the torsion bar adjusters is a great advantage of the torsion bar suspension. In most cases I'd say you're absolutely correct, dropped spindles aren't required.

But, as pointed out, when you start going over 1" for torsion bar diameters you run out of adjustment. With my small block car and 1.12" bars, even at max adjustment, my car sat at stock ride height. In order to get it any lower, I had to run the dropped spindles.

The drop spindles also offer the advantage of being able to get a proper alignment. Even a stock car, lowered significantly with the adjusters, may have issues getting its alignment specs right without the use of offset bushings or tubular A arms. Not saying they're a cure all, but they do have some advantages. As seen in this thread, they also have some disadvantages as well, but suspension is always a compromise.

Brad- interesting stuff on the C-body spindles! Would love to see some specs, and more info on how difficult the conversion actually is. Good stuff!

[Tom Quad]

I disagree about the need for dropped spindles and I question their bump steer geometry esp since they are untested.

I think the problem may be that when the torsion bars are installed in the car the lcs's are not "clocked" or positioned properly before the bars are inserted.   I have large 1.something T bars on an E body with no preload issues and the car sits low to the ground with the lowest pt [side exhaust tip] on the car   3.5 inches off the pavement. Low enough???   I also have a lowered mid size barge -Bbody with an iron head 440-and again no preload problems.  I have a R body lowered with really large t bars with no problems.  None of these cars have the lca bumper too close to the frame either...

[HP2]

I finally got my hands on the geometry program. It might take me a couple of days just to get all the new required measurements and sanity check it all. It's pretty massive, but also pretty powerful with all the analsis tools it has, so ths will be interesting to see how it all stacks up.

[brads70]

I finally got my hands on the geometry program. It might take me a couple of days just to get all the new required measurements and sanity check it all. It's pretty massive, but also pretty powerful with all the analsis tools it has, so ths will be interesting to see how it all stacks up.

Cool!   I think I have a set of c-body spindles coming and I just picked up the Howe( plus .500" ) ball joints today. They sure are nice pieces! Very low drag! I installed one today in the Hotchkis upper control arm! I'll take some pictures and post them. When I have all the parts( after Christmas) I'll start a new post "c-body spindle swap" or something to that effect on what I did.

[brads70]

Howe ball joints, top is stock as supplied by Hotchkis, bottom is with Howe ball joint installed.

Howe ball joint on the right

Top of Howe ball joint installed in Hotchkis upper control arm

[linetrash75]

 Found this calculator today measures SAL ditance to where a- arms would meet http://www.racingaspirations.com/?p=286 Sorri don't know how to make a link to just click on , somebody help me out?
 It also has a weight distrubtion , and frequencey calculator.

[brads70]

Found this calculator today measures SAL ditance to where a- arms would meet http://www.racingaspirations.com/?p=286 Sorri don't know how to make a link to just click on , somebody help me out?
 It also has a weight distrubtion , and frequencey calculator.

Interesting! Thanks for sharing!  I wish you could input the number instead of dragging it to the number, it's hard to get it exact?

[HP2]

Okay, I think I've got enough of this down to finally share some results. Please keep in mind I'm still learning my way around this, so I won't say these a guaranted results, but I think I've got a jump on it for the moment.

First up, a typical stock suspension mopar cranked down quite a bit. I took these from my car which is running a 26" tall front tire on a 15x8 rim, 4.5" back space.  Alignment is 3.22 caster, -.5 camber, 0 toe, RC height is 5.53.



Here is a corner shot with 3" of shock travel. That is a significant amount of movement. Note teh caster, camber, and toe changes. RC height changed only .03"  up.



Now here is a look at bump steer. This is only one side, but since the set up is symetrical, both sides are the same in this example. In 2" of travel, 1" jounce to 1" rebound, bump changes .2", or slightly less than a quarter inch.

[HP2]

Next up are using 72b&b measurements provided earlier in the tread. Since the plots for this are three dimesional, I did make some assumptions about fore/aft locations and centerline to outboard measurements using the numbers from my car. These should all be very close in cars using stock style components. What I wanted to capture was the change in control arm vertical locations.

First up is the static measurements. Tried to get caster, camber, and toe as close to the previous example as possible with 3.48 caster, -.5 camber and 0 toe. RC height is at 8.25".


Next up is the corner simulation. Similar types of movements in most locations. Toe changes are greater.


Here is a bump steer snap shot. I didn't get the scale the same, so it appears really bad, but you need to look more closely at the actual points in the similar range. Looking at +1 to -1 in range, we have roughly .15" per side for a total of almost .3" of bump through the range, or about .05" more than movement than a lowered stock set up.

[72bluNblu]

Here is a bump steer snap shot. I didn't get the scale the same, so it appears really bad, but you need to look more closely at the actual points in the similar range. Looking at +1 to -1 in range, we have roughly .15" per side for a total of almost .3" of bump through the range, or about .05" more than movement than a lowered stock set up.

Interesting. I thought the bump steer might be a little worse. I wonder if it would be better if I flipped the tie rods? Just eyeballing it, the tie rods would be fairly level if I flipped them from the bottom to the top. But that might be too much change (~2").

I'd like to get some better measurements though. I'm sure they're close, but obviously it makes a difference.

[brads70]

Thanks for sharing this , interesting info. Big difference in roll center heights, and bump steer, sort of what I expected.It would be interesting to play with tie rod location to see where it has to go to minimize bump steer? .400" in 3" is quite a bit. In the street stock class we usually get bump to about 1/16th in 3" That's with stock parts( modified somewhat, GM chassis)
 I'm sure it can be made to be better! Flipping the tie rod over would require reaming the taper to a bigger size and/or adding a sleeve. If you really wanted to get "serious" about bump steer you would have to make an adjustable center link, steering box and idler arm.

Member Bigs is setting me up with 73 C-body spindles, and I have a set of 74-78 C- body spindles sitting at my in-laws. They will bring them all up at Christmas. I'm looking forward to experimenting with them in the new year!

[HP2]

 I initially wondered how flipping the outer tie rod end would change things, but I haven't played with that yet to see. However, to do that in the real world would require mods to the steering arms, which would ralistically mean custom arms and then drive a change in ball joints. Feasible, but a lot of work for a street car.

Recheck the bump, it is .2 in 3" of shock travel.This program doesn't display the motion ratio from shock travel to wheel travel in the tables, but it does ask for it in the set up. I haven't verified on the car, but 3" of shock travel is probably close to 4.5-5" of wheel travel, or a more than most cars will ever see and a butt load more thana  car with 1.0" sized bars will ever have. I did chose a large range just to help illustrate the change. In reality, a car with big t-bars may only roll over 1.75-2.25 of wheel travel, or around 1.2 worth of shock travel, roughly half of the model I ran, which means in practical application, bump would likely be under an eighth, with the possibility of dialing in less with the end spacers popular in most competition catalogs.

I'm still learning my way around this thing, so there are probably things I haven't even scratch yet. For instance, if you look at the print outs, there is a corner optimization tab that allows to do iterative testing on a range of components seeking to optimize a selection of results for various positions in the corner. This tab can tell you how long the arms should be and what positions they should be mounted in. I'm sure it is all great info in the modified world where pick up points can be moved, and on most GM based chassis that can be easily accomplished. The Mopar layout does present several challenges to optimizing its layout within the confines of the stock frame rail and bushing designs.

[Tom Quad]

What is affected when the front spring eye is moved up in its mounting location, which effectively lowers the back of the car.