Someone told me the Granada brakes will work, but there may be an issue with "bumpsteer"? What's bumpsteer, and will the Granada setup be okay?

 

This ought to help explain it:
http://www.steeda.com/PR/Mustang/bum.../bumpsteer.htm

But I don't think it would be any worse with the Granada setup, as it has the same geometry as the stock setup. There may be inherent bumpsteer issues with the stock vintage design, but it hasn't ever been an issue in the last decade or so of driving for me. I'm sure this is something that would be amplified in race conditions.

 

:dance:

 

Ah, one of my favorite subjects.

Bumpsteer is "toe change occuring during vertical suspension travel". Basically, if one wheel hits a bump, and the other doesn't, that side of the suspension compresses, causing that tire to toe out, which makes the car "turn" that direction. The "bump" "steers" the car.

Bumpsteer also shows up under heavy acceleration (front end lift), and heavy braking. Severe cases can cause the front end to lift, toe-in, generate positive camber and STAY up, while under braking the car toes out and becomes very "squirrelly".

Stock Mustangs usually have some amount of bumpsteer. Lowered cars are usually worse, and changes to alignment, control arms, steering linkage, or SPINDLES can make it even worse.

Granada spindles have the steering arm (where the tie rod end connects) in a slightly different location than the stock Mustang arm. If they were NOT different, you could simply bolt the spindle arm with no alignment changes. As we all know, your alignment DOES change with the Granada spindles. In fact, it's a common problem to have too much thread length, and end up shortening the tie rod ends and/or sleeve. Why? Because the mounting point is closer to the center of the car than the original spindle. The leads to a shorter tie rod assembly. Any time the tie rod assembly is a different length or angle than the lower arm, you WILL have bumpsteer. :nono:

Now, some have advocated going to zero toe with Granada spindles as a cure. It's just a band-aid, as you still have toe CHANGE. With zero toe, you have helped the severe toe-in situation on lift, but now you have MORE toe-out under braking, making the car a handful in panic stops. I'm also aware that many people claim they have NO bumpsteer with Granada spindles - yet no one that claims no issue has ever gotten back to me with their bumpsteer measurements either.....

Bumpsteer measurement consists of measuring toe-in at 1/2" intervals thruout suspension travel and plotting the "curve". Ideally, you want a straight vertical line - that doesn't happen.

For a good idea what bumpsteer looks like, look at your car from the front while it's sitting on the ground - the tires are nearly straight on. Now, put a jack under the crossmember, and lift the car until the tires barely touch the ground. See how they are "pigeon-toed" (pointing at each other)? That's bumpsteer.

Bumpsteer should not be confused with Ackerman - that's toe change that occurs during turning. Granada spindles also have a problem there, but that's another lesson for another day! :bang:

 

Whoah, Bob just took me to school.

 

Professor Bob has studied at Granada College and received a major in Bumpsteer from it. I only minored in it since I dropped out soon enough and took up studies at Baer University. He also currently holds a dusty diploma from Versailles Tech (I believe a branch of Devry)...

 

No "schooling" intended. I hadn't seen your response when I started typing... Then "work" got in the way, and it ended up taking an hour + to type all that!

Good link to Steeda's site! HERE'S another good bumpsteer article also, as well as my suspension webpage .

 

No it's cool man, I obviously needed it.

I feel leik I is smrt now.

 

Thanks for the info, Cloney. BTW, I've been wanting to get rack-and-pinion steering for my classic Mustang. Anyone heard anything about this Flaming River setup that's available?
________
How Does An Mflb Work

 

Here's a post from VMF with some additional good information on bumpsteer and ways to solve it.

http://forums.vintage-mustang.com/forums/s...&gonew=1#UNREAD