Bump Steer Blocks

Kid Vette

Kid Vette

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Mar 25, 2008
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Santa Cruz, CA
I am finally getting around to cutting my springs to bring my Z height down to about 1". I'm thinking I should probably add some bump steer blocks. I think VB&P and Guldstrand are the only manufacturers. Anybody have any tips or tricks on this?
 
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Kid Vette said:
I am finally getting around to cutting my springs to bring my Z height down to about 1". I'm thinking I should probably add some bump steer blocks. I think VB&P and Guldestrand are the only manufacturers. Anybody have any tips or tricks on this?
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did I read somewhere your a tool & die maker or a machinist? I have a brand new set of blocks that never had the tapered tie rod hole finished...interested? send a PM.
 
Yeah Howard, I was a tool & die maker but I don't have the tapered reamer. It looks like it costs about the same as the blocks. Anybody have one I could borrow?

Thanks for the post Jphil! It looks like I will definitely need to do this. I noticed VB&P says "corrects steering angles for large offset wheels and tires". Anybody know what that is all about?

I'm no suspension guru, but I assume my goal here is to have the tie rods level when the car is at the finished ride height? I'm sure I'm oversimplifying.
 
VB&P is full of shit, it has nothing to do with large offset wheels and tires, those influence scrub radius, not bump steer. Bumps teer is a function of the unsprung and sprung mounted steering parts and the geometry towards the suspension components..

Check the tech articles, there's a bumpsteer article w diagrams in there.
 
OK thanks TT, that helps. I noticed that the article states that castor affects bump steer. Is that because it would be moving the outer pivot on the upper A arm in the vertical axis slightly?
 
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Well I cut off a half coil off the top (closely spaced) end of the spring and I don't think I'm going to take it down any further. The "Z" dimension is at about 2 1/8" but the front is about 3/4" lower than the rear and I think its going to look weird if I take it any lower. Plus the street is really crowned in front of our house and I'm afraid it will scrape if I go much lower.

On the subject of bump steer, I was reading Herb Adams' book on Corvette handling and he says, "The factory designs in a certain amount of bump steer to make the car understeer: the engineers call it "roll steer." A slight amount of roll understeer is beneficial, and stock Corvettes have the right amount. Unless you change the control arms, their pivot locations, the front knuckle or the steering linkage, you don't have to worry about bump steer".

So I'm probably not going to sweat the bump steer for now and see how it handles. Eventually I plan to go with the Global West CAs which will dial in more caster. I may check it then.

I also noticed in the "Vette Improvement Program" article, John Greenwood notes when discussing bump steer adjustment blocks, "When these blocks were first designed, three different thicknesses were made each for separate "Z" height. be sure to ask your dealer for a chart or graph showing the steering curve for the "Z" height you have selected". Seems like this would still make sense. Wonder why nobody does that?
 
Well, I buttoned everything up and now the front is only 1/4" lower than the rear! :crap: This is after I've driven it. My initial measurements were done with bolts finger tight, anti-sway bar disconnected and no shocks installed.

The only thing I can figure is the gas shocks raised it up. One of the things that leads me to this conclusion is before I cut the springs one side was quite a bit higher than the other in front. When I removed the shocks I discovered that one had been leaking and lost it's charge. So maybe that was causing the uneven height?

So can gas shocks really raise the front 1/2"?! :gurney:
 
Kid Vette said:
Well, I buttoned everything up and now the front is only 1/4" lower than the rear! :crap: This is after I've driven it. My initial measurements were done with bolts finger tight, anti-sway bar disconnected and no shocks installed.

The only thing I can figure is the gas shocks raised it up. One of the things that leads me to this conclusion is before I cut the springs one side was quite a bit higher than the other in front. When I removed the shocks I discovered that one had been leaking and lost it's charge. So maybe that was causing the uneven height?

So can gas shocks really raise the front 1/2"?! :gurney:
Click to expand...

Yes, easy.....
 
why not just remove (or unbolt from the lower arms) both shocks and measure again ? I doubt it makes a big difference though.....
 
MYBAD79 said:
why not just remove (or unbolt from the lower arms) both shocks and measure again ? I doubt it makes a big difference though.....
Click to expand...

I tried that today and you are right. It was no lower. I guess I will be whacking some more off the springs again. :smash:
 
the car should be level with the springs left/right at the same length. I suspect that on the side that sits higher the spring is not seated correctly.

I bought my 550lbs springs after I cut the 460lbs springs to get the ride height down, after I cut the springs I had some noise (clunking) when hitting a dip like at the end of the driveway... $70 well spent, the ride is not harsh like some vendors advertize, it really rides great even with low profile tires
 
MYBAD79 said:
the car should be level with the springs left/right at the same length. I suspect that on the side that sits higher the spring is not seated correctly.

I bought my 550lbs springs after I cut the 460lbs springs to get the ride height down, after I cut the springs I had some noise (clunking) when hitting a dip like at the end of the driveway... $70 well spent, the ride is not harsh like some vendors advertize, it really rides great even with low profile tires
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I agree. Up in the garage attic I have stock coils, cut stock coils, 460s, & cut 460s that I went through ---and in the end, the 550s were the ones that were best. The 460 & 550 are actually the same spring rating but the 460 has more coils thus effectively making it softer--but taller too, which is the kicker. If you cut a 460 to the height of a 550 it will be a 550 except it doesn't have the seating coil and won't fit as well in the spring pocket.

And no, the ride is not bad at all. It's not a Cadillac, it's a Corvette, right?
 
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