Assistance getting right measurements for shortened rear end?

[Nativefx]

I had asked a question about the best way to get the measurements I need to order a shortened rear end on my 69 Firebird in another thread, but thought I should start my own in the rear end "section" of Lat-G.

I found this link in a thread on PT and didn't know if this would be a better way to get measurements? https://www.cachassisworks.com/Attac...structions.pdf

Here is the link to my question to Vince of Meanstreets Performance who was helping out the OP. https://lateral-g.net/forums/show...573#post603573

From what I have been able to find, most recommend you have 1" from the inner fender to the inner wheel and at least a 1/2" from the outer wheel to the outside fender. This has at least been what I've found for other running a 4 link, and I am running the RideTech Level 2 AirRide. My concern is how much movement you will see during articulation of the rear suspension as I'd like to have my wheels positioned as far out as possible, but when I look up under the fender lip it looks like the inner portion of the fender "bulges" inward before going up and curving inward. Anyone have any pictures looking up to compare the amount of space they gave themselves without any rubbing issues? And will I need more space since I have the AirRide setup and when I decide to lower in completely?

Here's a quick pic I took with one wheel positioned.
[IMG][/IMG]


I just don't want my wheels set back to far in, but I also don't want any rubbing issues or my tires setting on the inner fender when its lowered completely. We set the wheels on dollies to move around and also lift closer to the estimated ride height but this made it very FRUSTRATING when trying to take an actual measurement and ANY slight but would move the dolly

Since I'm running 325/30/19 Pilot Super Sport tires on Forgeline 19 x 11.5 rims with a 5" BS, I have plenty of room inside the wheel well. Even where it's located in the pic above I have almost 1 1/2" between the inner fender and inner wheel. My best guess at the WMS to WMS with the wheels placed as about gives me about 54 1/2" - 54 5/8", which sounds okay but given some of the measurements other have used and then calculating out their overall width to the outside of the tires on both sides, it seems short.

I'm really trying to figure out what I can get away with "safely" without setting the wheels to far in. Trying to find a way to take measurements with a mock up have been difficult, so I'm hoping others have had similar problems and maybe solutions on the best way to go. Pictures of the space between the outer fender looking up as I posted would be VERY helpful. I need to retake with a ruler that can actually be READ.

thanks in advance for any wisdom people can throw my way!

[Vince@Meanstreets]

You can run pretty close to the outside. On the 69's there is a little bulge just above the lip. I've been a 1/2" from there and never rubbed. Since you have so much room inside go 1 1/4" if that is an inch you have going in that picture.

Most of the parts that rubbed was at the inner wheel tub.

[Vince@Meanstreets]

Rolling dolly's suck. I use a plastic milk crate or 2x4 cribs to check tire fitments. Use a rubber mallet to adjust.

You have to be acurate. Also don't forget to subtract the rotor hub thickness. 1/4"-5/16" average rotor.

[Nativefx]

Originally Posted by Vince@MSperfab

You can run pretty close to the outside. On the 69's there is a little bulge just above the lip. I've been a 1/2" from there and never rubbed. Since you have so much room inside go 1 1/4" if that is an inch you have going in that picture.

Most of the parts that rubbed was at the inner wheel tub.

Originally Posted by Vince@MSperfab

Rolling dolly's suck. I use a plastic milk crate or 2x4 cribs to check tire fitments. Use a rubber mallet to adjust.

You have to be acurate. Also don't forget to subtract the rotor hub thickness. 1/4"-5/16" average rotor.

Vince, thanks for responding. I thought I should start my own post even though I had asked you a question in someone else's "wheel & tire" post.

So your suggesting I go 1 1/4" from the outside fender lip to the tire rather than try and get closer to 1/2"? Is that due to the AirRide, especially when lowering completely and the bulge above the lip? If I raise the tire further into the wheel well maybe I can figure out about how far the highest it will tuck in order to clear everything.....

I'm already about 1 1/2" from the inner wheel tub to the tire with the tire where its at. I was just trying to figure out if I still had room to safely move them outward. I should probably take a picture looking down the sides and up to hopefully be able to compare with others who might have the same picture angle.

I agree the dolly idea didn't work well at all! I think your idea about using a milk crate would be much better. It's tough trying to keep the wheel parallel with the body especially when making adjustments. I wasn't sure how accurate you had to be when measuring which is why I was hoping to get some input. This was also the reason I chose to go with 11.5" wide wheels and 325mm tires rather than stuff as much as I could underneath. The 325's are HUGE so I don't think its going to take anything away from the look Im after.

As I mentioned before, I realize there is some adjustment to help center the rear end but I wasn't sure how much? Also knowing the tolerances on these older cars were NOT very close, I'm wondering if I go with weld on brackets for the suspension since i'm ordering a new rear end, what is the best way to determine where these should be mounted? I'm also wondering about your comment in the other thread about turning the offset lower links in order to gain clearance from the bottom mounting position of the shock. I'm close to the suspension mount on the driver side right now, but we haven't touched the mounts and I don't know if they are positioned there to center the stock rear end (i'm assuming they are but don't know for sure). Is it fairly easy to determine the bracket location if we were to turning the lower links around?

I'm looking at going with a floater rear end which is nice as I won't have to worry about rotor hub thickness. So if I can accurately get a WMS to WMS measurement I should be ready to order my rear end.

thanks for your help!

[Vince@Meanstreets]

In that picture it's 1/2" or 1"? Tough to gauge. Is that 1/2"?

What I do is raise the tire higher that wat it would be at ride height.... Dump the car and see where it MIGHT hit. Space 1/2" from that point. If I wanna go further I modify what I have to modify to get it flat back there. Cut lips, outer wheel houses etc. Easy to do on a car that isn't painted yet.

[Nativefx]

Originally Posted by Vince@MSperfab

In that picture it's 1/2" or 1"? Tough to gauge. Is that 1/2"?

What I do is raise the tire higher that wat it would be at ride height.... Dump the car and see where it MIGHT hit. Space 1/2" from that point. If I wanna go further I modify what I have to modify to get it flat back there. Cut lips, outer wheel houses etc. Easy to do on a car that isn't painted yet.

that's about an inch from the inside lip. I'll have to get a better pic with a ruler you can actually read!

I think I may be able to get a couple milk crates and I think your right, I should raise it higher to where I think it should be when it's dumped. Unfortunately the body is already painted. If I had to modify the inner fender, I could but I'd just be worried about welding something back in place to seal it off. I already had to cut the inner fenders on the front in order to clear when it is fully dumped, but that was much easier.

[Nativefx]

Anybody have an idea on a good size to make the 2 x 4 cribs? I'm at work and can build some with cutoff material, but I don't have the wheels here with me to try and fit.

Maybe 20" x 20" or 18" x 18"?

thanks

[Vince@Meanstreets]

Originally Posted by Nativefx

Anybody have an idea on a good size to make the 2 x 4 cribs? I'm at work and can build some with cutoff material, but I don't have the wheels here with me to try and fit.

Maybe 20" x 20" or 18" x 18"?

thanks

https://lateral-g.net/forums/show...ght=DSE+stands

We run alot of big wheels here and 14" runs work well. My buddy almost lost a car on his 12"s

[Nativefx]

Originally Posted by Vince@MSperfab

https://lateral-g.net/forums/show...ght=DSE+stands

We run alot of big wheels here and 14" runs work well. My buddy almost lost a car on his 12"s

Thanks for all your help Vince!!