I don't worry about steel getting soft from welding. I gets hard and brittle, with added residual stresses from localized heating and cooling. Cracks can magically appear and grow very quickly when welded parts go through relatively few stress cycles. After welding, if you can reheat the entire part and let it cool as slowly as possible, residual stresses are relieved.

I had looked at adding more tube also. The modifications would be irreversable and it seemed like a large step to make without some first getting positive results from some first steps.

I'm planning going ahead with single big spacers. I've got plenty of material in to make them now. I just need to get some time on a milling machine. The 2 bolts clamping those spacers on will only be in tension, as with the original deisgn, if you make the spacers are made correctly (see my rendering). Of course you wouldn't want to use any old bolt.

Ford rod end for tubular arms should get more clearance. I had considered them for a tubular arm project, but I don't see the need yet since I have no heim joints in my suspension yet.

Changing the steering arms to heims may be necessary now though. We will see how it goes. I'll probably start the mods next week. We're autoxing on Sunday so I didn't want to get stuck with the car on the jack stands this weekend.

That said I like testing different things out to see the differences they make. I think it is necessary to acquire knowledge. To me that is the most important result of the process.

While on this subject . Anyone have a set of used or new bumpsteer spacers they want to sale ?

Mike

I worked on this some over the weekend. I settled on 2 3/8" spacers. I managed to mess up one of them already. Working on the second. The mill I am working with is missing it's vise, so I am set-up challenged. I managed to mill out the protrusion on the top using a rotary table and some clamps to hold the work down, but I really underestimated the trouble it is to to put a matching hole in the bottom of the piece that concentric to the protrusion on the top. Good thing he has a lathe too. I think I'll make the next one using a boring bar to make the hole first. One thing to watch out for, there isn't a lot of clearance between the bottom of the spacer and the brake disk with such a large spacer.

Given that 'bump steer' spacers increase the distance between the axle and the lower control arm outer pivot point, does this change have any side effects? Other than changing the roll center?

The question is asked because an alternative method of changing the roll center is to raise the lower control arm inner pivot point. Which change does not appear to have any side effect, other than the usual bump steer implication.

Raising the inner pivot point is an option, but to raise it high enough for my purposes, it would need to be up in the motor mount somewhere. Definitely a problem. There are issues with steering knuckle rod-end clearance and brake rotor clearance. Then what to do with the sway bar. I've got my spacers nearly complete so I'll let you know when it is finished.

I made my own bump steer spacers doing all the lathe work first, drilling the mounting holes in the mill and then cutting the final shape on a band saw.

One thing that may be against spacers is the resulting increased lateral bending load on the strut. The bigger the spacer the greater the effect, would tend to cause the shock shaft to bind too.

Sorry to bring this thread back from the dead since half the pictures are now garbled, but I found a business up the road from me that makes 1 3/8 inch spacers to fit a Z. http://www.technotoytuning.com/t3_si...ducts/rca.html
I will check the fit on my 280 struts.

Does anyone know if I had my two sets of 3/4 inch aluminum spacers tig welded together would there be any problems such as softening from the heat? The 1 1/2 inch trial seamed to fit nicely with no clearance problems on the 16 inch wheels.

I don't think you have anything to worry about. I've seen wheels TIG welded in the center that held up fine. You could get fancy with tubing and do something similar too. And if you're doing a spacer this thick you could have one doubled up that lets you change the pin lead so you can try running large amounts of caster and/or concert the bottom to a double shear mounted monoball.

Cary

Thanks Cary, I might try the tube route.

Just wanted to chime in on this thread a little bit. I don't autocross my ZX, but I plan to eventually. After lowering it and putting the 17" wheels on it, it was scary to drive. It decided which way it wanted to go more than I did. It was especially hard to control under hard braking. It was at the MSA show that someone told me about the bumpsteer spacers. I couldn't believe the differnce they made after I put them in. All of the weird squirliness was gone. The biggest thing I noticed aside from the control issue was that it brought back the caster to where it should be and the steering wheels natural tendancy to return to center came back. Anybody and everybody with a lowered Z NEEDS to have these. Great ideas in this thread guys. Some of you are incredibly knowledgeable. It gave me a lot of ideas for future upgrades.

Rod.