Rack width question

[dirtslinger71]

Just had my Mastersbilt front clip updated to the new "r series" design. It's the same basic design as the genx from what I can tell. Just raised rail and crossmembers higher. But now they want a 19 1/4 rack instead of a 18 1/4.... The lowers are still in the same location as older clip so I didn't understand why the width of rack should change. I confirmed this with Keith and he said it's to do with the left side steering. I guess ackerman... But my main question is I'm trying to be a cheap ass and just add a 1" extended rack eye to make it 19 1/4. Should I put it on the left side or right side? I'm thinking I will gain more left steering if I put it on left side. Would I loose left steer if I put it on the right?

[TheJet-09]

Did they give you a measurement for the tie-rods themselves, or at least the LF? If they did, I think that would dictate what end you could put it on. Otherwise I could see adding an inch to the RF maybe giving you a little more steering to the right as the "rack" itself would then be slightly to the left to keep centered...if that makes any sense.

What type of rack eyes do you need though? Like a center pull for the RF, or are they dropped now with the crossmember even higher?

I'm glad to see they're at least changing things up.

[dirtslinger71]

He said set the left the same as before and adjust toe with the right side. That's what kinda throws me off about the whole wider rack deal. He also still says to use the center eye clevis on the right and a standard end on the left with a 1/4 " spacer between the heim and rack eye.

[billetbirdcage]

https://i.imgur.com/cCrakah.png



I haven't been around that many mastersbilts but I have yet to see one anywhere close to correct as far as rack mount being in the correct position and being lined up even close with the tie rods lengths they listed.

Once that is correct: How far the car turns left or right is set by where (left to right position) the rack mount is welded to the car.

*Note the above is more for a symmetrical front suspension, but search bumpsteer inner tie rod position and you will see what I mean

[TheJet-09]

Huh. Assuming lower control arms are the same length as the old, and center to center of their mounting points is the same as the old, and the same length LF tie-rod, you'd end up with a shorter RF tie-rod than before (with a wider rack).

What about spacers between the tie-rods and spindles? I think the RF called for a 0.500" before. And if they raised the cross member even more, I would think you'd need different ends on the rack. Maybe it was raised very little?

I'd measure your center to center on the lower control arm mounting points, just to be sure. I think they are/used to be 17 5/8" with the 18 1/4" rack (or real close, maybe 17 7/8", but definitely less). I can measure my 2014 Gen-X tomorrow, for curiosity if nothing else.

[TheJet-09]

I just saw Billet's post. When I was down there a couple years ago, Keith said their reasoning for the set length on the LF was so you could basically guarantee the RF tie-rod would be longer than the RF lower, so when you wreck and have to do the "Chinese fire drill" as he called it, and don't have time to get everything precisely set.

[dirtslinger71]

Huh. Assuming lower control arms are the same length as the old, and center to center of their mounting points is the same as the old, and the same length LF tie-rod, you'd end up with a shorter RF tie-rod than before (with a wider rack).

What about spacers between the tie-rods and spindles? I think the RF called for a 0.500" before. And if they raised the cross member even more, I would think you'd need different ends on the rack. Maybe it was raised very little?

I'd measure your center to center on the lower control arm mounting points, just to be sure. I think they are/used to be 17 5/8" with the 18 1/4" rack (or real close, maybe 17 7/8", but definitely less). I can measure my 2014 Gen-X tomorrow, for curiosity if nothing else.

I will double check later but I measured 18 1/4 between the lower control arms thats why I would think a 18 1/4 rack would be ideal for the application... As far as I know it's no spacers between the spindles and tie rods.

[TheJet-09]

I just measured my 2014 Gen-X and it's 17 5/8" center to center for the lower control arm mounts. I know my '07 Smackdown was the same as well. That's probably where the difference is and why it needs a wider rack.

Others could explain it far better than me, but if you look at a spindle the tie-rods mount "outside" of the lower ball joint, which is why I believe the rack is actually wider than the lower mounts.

[billetbirdcage]

https://i.imgur.com/VWkmBFa.jpg


Like I said the even/equal measurement I posted earlier is related to both sides of the suspension being the same, but typically you will be somewhat equal on both sides and it sounds like what they told you won't even be close. But again it depends on the A-arms and spindle locations. Since typically all LM's have the tie rod end mounted outside the lower arms ball joint (opposite of the lower part of the drawing I posted), thus the reason your typically mounted outside the lower arms a small amount (rack wider then lower arm spacing).

Obviously these numbers/pictures are Ideal and can be fudged some without too much bumpsteer or problems as everything on a car is a compromise to some degree. Then how much bump out you want is directly related to how much Ackerman steering is built into the car, typically the less Ackerman the more toe out you want on the RF and vice versa.

[dirtslinger71]

I don't know why I didn't think about the steering arm being outside of the ball joint. But that makes perfect sense! I guess with other stuff that I had to figure out bump steer on the steering arm are more in line with the ball joint. It definitely makes more sense to me now. Thanks guys. Also I think I'ma add my 1" extension on the left side of the rack because I feel that I will gain left steering and will need that more than right steering...

[dirtslinger71]

I just measured my 2014 Gen-X and it's 17 5/8" center to center for the lower control arm mounts. I know my '07 Smackdown was the same as well. That's probably where the difference is and why it needs a wider rack.

Others could explain it far better than me, but if you look at a spindle the tie-rods mount "outside" of the lower ball joint, which is why I believe the rack is actually wider than the lower mounts.
This new clip is 18" center to center on the lowers. Left lower is 17 3/4" and right is 19". Still uses the same uppers. 8 1/2 and 11 1/4.

[TheJet-09]

Thanks for the info. Different spindles though?

I saw a picture of an updated front end Booze Brothers (Pennsylvania) put on one, and I noticed the RF upper mount was curved in slightly, similar to what the LF mounts have been for a while now. I was wondering if they went to a longer RF upper or something. But maybe Booze Bros. is doing their own thing.

[dirtslinger71]

Thanks for the info. Different spindles though?

I saw a picture of an updated front end Booze Brothers (Pennsylvania) put on one, and I noticed the RF upper mount was curved in slightly, similar to what the LF mounts have been for a while now. I was wondering if they went to a longer RF upper or something. But maybe Booze Bros. is doing their own thing.
That's probably my car. They are the ones that did it. It takes almost 2" of spacer on the rf upper to get the camber right. Keith said he did that because he thinks a longer rf upper will be better but it's untested. So it's like that for the future. I heard the longhorns are the same way..

[collateralDamage]

You can change the rack shaft and cylinder rods to change over your 18 1/4" to a 19 1/4". You are probably going to need slotted ends for the rack too....