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CSRP 65-66 drop spindles on a 69 mustang?

7K views 16 replies 8 participants last post by  fish2keel 
#1 ·
Guys, lots have been posted on running later spindles on a 65-66.
What are the pitfalls with running the CSRP drop spindles for a 65-66 on a 69 mustang?
Bumpsteer?
It seems that no one makes a dropped spindle for a 69 other than Maier racing.
 
#2 ·
I would think it would mess up the geometry and cause bumpsteer and other problems.
 
#3 ·
I think the steering arm is shorter on the 65-66.
The Pro Motorsports kit effectively shortens the steering arm to prevent bumpsteer on the 69-70.
So it might work.
 
#4 ·
I had nothing to do late one night at GW, so I drug out a bunch of spindles
and did some measuring. Unfortunately that data is buried here somewhere,
so not looking at my notes, but from memory, it's not the length of the arms
as much as the positioning (and height) of the end of steering arm in your
comparison.
It is very likely you would need to mod the bumpsteer of the early arms
AND fix the tie rod holes...... at the very least. (or maybe the tie rod holes
are already bigger on his drop spindle- I don't recall)

ex-Global West GM
1991-1995
 
#5 ·
It's a known fact that the spindle threads and the tie rod's hole are smaller on the earlier cars. Those aren't too hard too overcome themselves but I believe as GT289 mentioned, the arm is in the wrong location for a 69.

You might send a PM to Dennis at CSRP or maybe he'll chime in with more info. I wish someone made one for a 68, too.

The Maier unit forces you to use a Wilwood kit for brakes if I remember, that alone is a huge turn-off for me, on top of the less then mediocre customer service Maier seem to have sometimes.
 
#6 ·
Yes the Maier units dependence on Wilwood is an issue for me too.
I am going to keep my big Lincoln Trans Am brakes no matter what. I can used that setup with the CSRP spindles.
 
#7 ·
Just wondering, do you not like Wilwood or just the fact that Maier requires you have to use Wilwood instead of OEM type brakes?
 
#8 ·
Guys, lots hyave been posted on running later spindles on a 65-66.
What are the pitfalls with running the CSRP drop spindles for a 65-66 on a 69 mustang?
Bumpsteer?
It seems that no one makes a dropped spindle for a 69 other than Maier racing.
I'm not an expert on suspensions but I have spent a lot of time on my 66's. I'm using 72 spindles and SoT parts. I'm familiar more with the quirks on the early cars then the later as there are some changes. I have spoken with Dennis on the phone from CSRP about the differences. He told me the the early spindles have .500" more offset to them. I'm pretty sure he said in posts on the forum that the angle of the tie rod arm is the same as well. That makes sense as the wheel base is exactly the same from 65 to 70 and the Ackerman would be the same. I do know that the length of the tie rods are the same. I measured them. I believe that number is 6.25" from the center of the ball joints to the center of the tie rod end.

I needed to know this for the bumpsteer issue I was having even before I ran the later spindles. I remember reading a post a long time ago related to bumpsteer on early cars with later spindles. It was suggested to set caster at 5° to reduce the effect of bumpsteer. At the time I didn't understand but one day it hit me. As you add caster the spindle is obviously tilting back. This lowers the outer tie rod closer to the road. If you divide 6.25" / .500" = .088 which is the sine of 5°.

As you lower the outer tie rod in order to correct toe back to normal you have to increase the distance between the inner and outer tie rod. This causes a more gentle arc and effects less toe change. I believe this is why the Promotorsport bumpsteer kit moves the tie rod out. It does the same as lowering it except you don't have ground clearance issues. They always say the tie rod arm needs to be parallel to the LCA which I can agree with generally but what I think might be more important at least on our cars is how long the tie rod assembly is. I've come to think you can't make it long enough on our cars. I run a Baer bumpsteer kit on my car. I started to make a bumpsteer gauge, it almost done but I ended up tuning my suspension the Redneck way. Driving it over the crest in my road and adding shims in till the bumpsteer was gone or at least not really noticeable.

Another thing I noticed on my car whither the front end on Jack stands with the suspension at full droop. Before the suspension ran out of travel, the outer tie rods or I should say the rod ends on the bumpsteer kit ran out of travel and bound the steering up. At this point the camber went positive and the tires toe In severely. Sound familiar? I realized that it could be due to the fact I'm running rod ends that have been lowered working at a greater angle but I wonder if the same happens with stock tie rods but we don't see it because of the boot?

Keep in mind ad you add caster, it'll have some effect on the ride height of the car because as the caster angle of the spindle increases the vertical distance between the upper and lower control arm decreases. Again I'm just sharing what I have learned while fooling around with my car. Maybe something may be helpful to you. My last comment I would say set your car up how you like and see how it sits. It all effects ride height. My car sits a good 1.5" lower maybe more and I haven't done anything to specifically lower the car. I'm glad I didn't!
 
#9 ·
All,

I have enjoyed reading your posts regarding CSRP drop-spindles, caster, and suspension and steering tech. I've got a 68 that I've owned for awhile... originally all stock when i bought it in 1988, I later did a full swap from PS to manual with 16:1 Flaming River box. Still too sloppy and it darted in and out of every groove. I've been running 16x8 wheels with 225/50, 1.5" shelby drop, and have it set to 3 degrees caster - but still no fun to drive. All else works fantastic, but the steering has killed the joy.

This winter, the car is back on stands for more work/mods. I have installed a KRC powered Steeroids rack with 2.5 turns, have roller upper arm, roller perches, Maier's Ultegra shocks, progressive rate springs, and just today -- CSRP drop spindles were ordered. Re the spindles, I'm already running a 70 drum, so the bearing set is no issue. The issue now though, as Hushkinhano mentioned, are the 65-66 spindles for my 68, and potential bump-steer.

Here are my options: I have both the Pro-motorsports kit (lowers and moves outer-rod in) as well as a TCP bump-kit (only lowers). I will be running 4 degrees caster (per Steeroids), 1/8 toe, and .5 degree neg camber. I have adjustable strut-rods, so no prob. Back to my question -- advice / suggestion as which bump-kit to run? Other info related to front suspension and steering would be lovingly welcomed. Summer is coming...
 
#10 ·
The darting on the road really has very little to do with the box unless it was really worn out. I would check the lower control arm bushings. Not only does they have to twist up and down but do it in an arc as well. Once these bushings wear it can cause this. You could have trammling which is common to wider tires and makes the car do this. Some brands are worse then others I understand. I know someone with a ZO6 Corvette and he says his car is really bad. Check worn strut bushings or idler arm. Once you get rid of worn parts and a few degrees of caster, it'll drive pretty well.

From my experience on my car in regards to bump steer. I called Dennis from CRSP a while ago when he was working on his drop spindles. When I asked about geometry he said the only difference between the 65/66 spindle and the later Mustang and Granada is the 65/66 has .500" more drop or offset. The length and the angle of the arm are all the same. So Ackerman and steering ratios are going to be unchanged. What I have come to the conclusion about bumpsteer kits is this. It's not so much if the tie rod assembly, meaning inner, outer and sleeve is parallel to the lower arm but more that they swing in similar arcs. To do this you want to increase the length or distance between the inner and outer tie rod centers. By lowering the outer tie rod such as a typical bumpsteer kit, this causes exactly that. The Promotorsport does this too by lowering the arm and moving it out as well as moving it forward to make the steering quicker. Adding caster will also have the same effect as a bumpsteer kit to a point. As you add caster, the outer tie rod moves closer to the road surface. It will also increase toe out. When you correct toe you will have increased the length of the tie rod assembly, making a more gradual arc and reduce bumpsteer. For each degree of caster you lower the tie rod to the road surface about .100". I don't think you'll have any issues putting a spindle in such as the CSRP 65/66 drop spindles in a later Mustang and have adverse issues. It's basically a built in bumpsteer kit. I'm not crazy about the Promotorsport kit because you have to drill out the taper. If you don't like the kit or it doesn't work for you, that leaves either buying new spindles or have someone weld them up and put a new taper back in. This could be an issue if you have state inspection if they don't like the kit. I have the Baer kit in my car. I can easily remove it if that becomes an issue for me. I haven't had my car inspected yet with the kit.

In closing I have eliminated every rubber bushing in my car. Even the idler arm. The steering is nice and precise, no slop. I run 4° caster. My last bit of advice. Learn as much as you can with all this stuff. It's invaluable in getting your car to drive nice and fixing problems that will show up. Otherwise you're chasing your tail and wasting money. When you start to modify you need to understand what will happen both good and bad. This is based off my experience as a noob with this.
 
#11 ·
For a reference point of view here is my 66 as it sits now. It has the upper arms lowered 1", stock uncut GT spec coil springs. I know you don't have a 66 but you get the idea on how mods can unintentionally lower the car. I was going to cut about a half coil off before I installed them. I am so glad I didn't!

 
#13 ·
Thanks, Gentlemen, for the wisdom and advice -

Here's how my car sits (most recent pic I could find) with 1.5" shelby drop, new front suspension (as of 2009), etc. With new bits as I mentioned above, I won't cut the springs until after an alignment & everything settles in. I want my car low (as in above picture, but not slammed). Thanks again for the suspension / steering tech info. Much appreciated!
 

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#14 ·
That's a nice looking Mustang! If you did that work to your car yourself at home, believe me you can do a alignment at home. It's worth the time and results. It's not hard to do and doing it once will pay for the gauge. I did a post on DYI home alignment a while back. Do a search on all the horror stories of sending your car to a shop. Most shops won't know how to really do a alignment on early Mustangs and if they figure it out, they'll want to set it to stock specs which are not good for today's driving.
 
#16 ·
I agree with what GT289 said about a professional alignment. I was suggesting doing it at home over the usual chain store that has mostly worked on strut cars. There's been more then once someone here that have had the shims fall out because they didn't tighten the control arm bolts or completely ignored the owner's specs and set it to stock. It's a good way to learn. Honestly my first alignment was meant to be a quicky so I could do a shake down drive. I did't spend too much time but did get it pretty even side to side and the car drove great. The steering wheel was straight and the car tracked straight. It didn't pull to either side. I ended up leaving it for a year.
 
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