AST4150 to Spindle Mounting Clearance

[racer47]

There is about 0.050" of a gap between the inside of the AST mounting brackets and the spindle. That seems like too much to me. Are they all like this? The bolts will pull it tight but that seems like a lot of unneeded load on the bracket welds plus using up some of the bolt clamp load to deflect the brackets. I'm considering shimming them for a snugger fit. Any thoughts?

 

[Grant 302]

I wouldn't worry about 0.050", as long as the housing isn't aluminum. That bracket 'sees' a lot of force anyway. A little pre-load isn't going to matter much, IMO. At least you don't have to pry them apart to get the spindle in!

 

[302BOB]

For anyone not familiar with the measurements being mentioned here....0.050" is 0.0125" away from a 1/16th of an inch. Some may not know but most will. I was a machinist for close to 40 yrs , so I know my "thousandths".

 

[racer47]

0.050" is 0.0125" away from a 1/16th of an inch

I think that you are implying that 0.050" is not a trivial amount. If so, I agree. I think that is too much deflection on a bracket that is only 1" wide (and half of that to the center of the mounting hole).

I already started making a shim out of 18 ga sheet steel (0.048" thick). It may not be necessary but I think it is the right thing to do.

 

[wwilde001]

So I got a box of miscellaneous hardware including studs, lug nuts, nuts and bolts etc. from the race shop once they completed my build. Low and behold I remembered after reading this post that there were four shims that were in there, but I had no idea what the hell they were for. Now I know. They measured out at .048" thick. On there way to @racer47.
Good Luck with your build!

 

[racer47]

Thanks. I was not comfortable with that much clearance. Also glad to know that I was on the right track with shimming it snug.

 

[modernbeat]

They were not originally built with that much clearance. And that seems about the maximum of what I'd allow on a car, but would not reject them.

 

[racer47]

Thanks for taking the time to read and reply. I've got shims coming in the mail. When I get them, I'll decide if I like those or mine better. Either way it'll end up being a much better fit and I'll put all that bolt stretch into clamping force and not bracket bending force.

 

[steveespo]

Good observation and decision. The clamping force of the strut flanges to the spindle ears is a critical value. Point loading will lead to failure especially under high loading. Ford had a couple spindle and fastener revisions on the S197 to address this. Good catch.


Sent from my iPhone using Tapatalk