[redmondrr]

Looking to improve the steering on my 68 FB 400 convertible. I need better road feel and less wandering. Has anyone fitted a later steering box? If so, from what vehicle and what else needs to be replaced. Many thanks!

[JLMounce]

The wondering is a combination of things, not just the box. A new box can increase road feel of course. The Lee rebuilt boxes always get a nod for feel. I'm fairly certain you can also get a 90's grand cherokee box in there which is a cheaper alternative. I believe you need a different rag joint for those, but my understanding is it's a fairly straight forward swap.

To fix the wondering, you have to address the suspension system itself. The first gen system has quite a bit of bump-steer in it and the soft rubber bushings allow enough deflection in the control arms that you have a constantly changing alignment. As a result the car tends to wonder around on anything but flat, smooth, even surfaces.

Depending on your budget and what you're ultimately after, there's options available to you.

If you're not looking or needing the car to handle much better than it does now, but you just want to get it driving a bit better, I'd do the following.

-Steering system rebuild. Get new ball joints in the steering arms and get your current box rebuilt, or replaced.
-Replace the factory bushings in the upper and lower control arms to delrin bushings
-Replace the upper and lower ball joints. Use a quality Moog lower joint and a pro-forged .5" tall upper joint
-Address bump steer to the extent you can. There's several ways to do this that I'll detail below.
-Include a modern alignment and radial tires. For a street car, shoot for -.25 to -.5* camber. 2* positive caster (or as much as the arms will allow), 1/16th toe in.

In regards to the bump steer issue, the first gen suspension is rear steer. That means that as you increase positive caster in the alignment, you actually help bump steer in the car. However with factory arms, it's almost impossible to get anything more than about 2* of positive caster. On the street you want around 5* in these cars. That typically means going to aftermarket control arms which can get expensive pretty quickly. Adding that much caster also moves the wheel in the wheel well and you can end up with rubbing issues at full lock, unless you're running an arm package that re-centers the wheel by moving the lower ball joint pickup.

I would recommend giving this page on first gen bump steer a once-over. There is a template for bending the tie-rod mount on the spindle as well as a form for determining how much bump steer you have.

http://pozziracing.com/first_gen_sus...m#Bump%20Steer

I'll note a lot of people are afraid to run solid bushings in the arms for fear of adding NVH. I've been running delrin bushings in my setup now for several years and in truth, the rear with it's leaf springs and rubber bushings is more harsh than the front. If you're completely afraid of them and not willing to try them out, you can try a poly bushing or a high durometer rubber bushing. The goal is to only allow those control arms to move in the direction they are designed for however.

That's about the cheapest way to get the car driving better with the stock components and minimal modification. If you want to go a little further you can start looking at doing the guldstrand mod, or spending the money for aftermarket equipment which really starts opening up other options.

[Tim john]

Nice advice by Jason, well said.

I had my original 69 Firebird steering gear box re-valved by "TurnOne" in Saginaw, Michigan. It is now 2-1/4 turns lock to lock. It is super nimble and precise. As for other suspension and handling components take the time to look at DSE (Detroit Speed & Engineering) for F body handling and performance suspensions. I installed the DSE upper and lower tubular control arms, DSE solid aluminum body mounts (stock height), DSE front drag link, DSE adjustable shocks front and rear, DSE mini tubs, 2" DSE lowering rear leafs, DSE offset shackles, 2" lowering front coils (DSE). I also installed a Borgensen stainless steel U-joint to replace the rag joint for the steering, The car handles like a modern performance vehicle considering I still have an original sub frame. It is really remarkable on how well the car handles and performs with these enhancements.

Tim john---

[Speargun]

I put an 88 IROC box in my '67 and it rides like it's on rails. I also have Global West A-arms & coil overs which help the geometry, but the IROC box has a MUCH better feel than the factory box.
You'll need a newer, higher pressure, pump, new rag joint, and new hoses or metric adapters, but it's worth it.
ProTouring forum has all the details on the swap.

My IROC box developed a leak so I threw in a box out of a 98(?) Grand Cherokee as a quick fix and it feels about the same so I think that pretty much any newer Saginaw box is going to be a big improvement over factory.

Factory A-arms could use some modifications to improve geometry, but also make sure that all of the tie rods & steering linkages are good and don't have any slop in them.

[RocktimusPryme]

I actually recently did this. All in it was maybe $300 and might be the best bang for the buck value I have gotten out of the car.

I used a 3rd gen steering box, not the IROC box but the standard Z28. Some reported the IROC box as too stiff for their liking.
I bought quality front shocks, Bilsteins in my case. It already had new KYB cheapies, but the Bilsteins made a dramatic improvement even over new shocks.
I replaced the pitman arm, ragjoint and tie rods with new ones.
Then at the end of it I had a new professional alignment done.

For a few hundred dollars the car went from kinda scary to drive all the way to feeling close to a modern car.

I did later add the cost of a new PS pump with the higher pressure valve, but honestly it drove fine before I had it. Considering the cost of the pump, and the PITA to get lines and all that to fit, it might be worth the price to have your factory steering gear rebuilt to the specs you want.

Honestly I would start easy and cheap. Replace the steering linkage components and the rag joint. See if the slop you are feeling is coming from worn components and maybe do a small manual adjustment on the steering gear. Get a professional alignment. You may find that fixes your issue. If not, then go back and replace the box, which is a larger surgery.

[redmondrr]

Thanks everyone! Great advice and information.