wheelbase and wheel track measurements

[grooml]

I just finished installing hubs rotors etc. My control arms are level and I measure 89.5 inches for the wheel base, and the rear track width is 59.5 inches face hub to face of hub.(with rotors on) It is also pretty square right of the start. I'm only out of square 1/4". When they say 90" wheelbase, and 59" hub to hub with rotors on, is that exact or approximate. Should I change what I have now to meet the measurements shown above(90" and 59")
Thanks in advance.

[GoDadGo]

Grooml,

When you do the alignment things will shift around a tad because of the Caster Angle needs to be taken care of.
If you have an IRS set up then that will make for some interesting issues too, but they'll pretty much take care of themselves when properly aligned.
If you have the 3-Link, then check your side to side measurements to the shock mounts to set your Panhard bar.
Also, your pinion angle can greatly affect your wheelbase more than you would realize on a 3 link set up depending on your upper link installation length.
Finally, Welcome Aboard & Welcome To The Factory Five Forum Family!

Steve

[grooml]

Steve,
Yes it's the old t bird style IRS. I did a basic caster/camber setting, although nothing real accurate, I had an old caster/camber gauge from years ago when I was racing dirt oval. But it will definitely get a proper set up when ready. After reading on here about setting up these IRS's for a few years, I was surprised how square it is right from the start, some tweaking at the end, and it should be fine. I just didn't know if the measurements given in the manual or online were to be followed to the 3rd decimal place or if 89.5 inches is acceptable. I guess its just how the wheels look in the wheel well.

[GoDadGo]

If your wheelbase ends up being 89.5 then I don't think it really makes a difference.
I purposely shortened mine to 89.25 because I wanted the rear wheel to be centered within the rear wheel well arch; however, I'm running a 3 link.
Hopefully your rears will be centered too.

https://youtu.be/IGYtX-3p7xk

[grooml]

Thanks Steve, Quite the video showing the car, as well as the Hurricane water levels. My main home is here in Canada about a 2 hrs drive north of Duluth. But I have a modest vacation home in Sebring Fla. I'm always glued to the weather network during hurricane season, when I'm up north. We had Irma last year, but it was nothing compared to what you showed in the video. Glad all your family was safe.
Larry

[CraigS]

On the T-bird IRS, the front mount rod end for the LCA should have shim washers on either side of the rod end where it attaches to the frame. You should have the same number of washers on left as on the right. So this locates the the both LCAs front to rear w/o much room to vary. So this sets the wheel base. How far the rod end is screwed into the LCA determines track although there isn't a lot of room for that to vary either. Also, make sure you have the same number of rod end threads showing beyond the jam nut on both sides. Getting the thread count and the washer count the same and locking the front mounts down is step one. You won't touch them again unless you make an overall change to the setup. BTW, leave all the washers out of the rear LCA mount until you have the alignment finalized. Reason for this is that, as the rod ends are screwed in and out of the LCA, the distance between them will vary. You do your toein adjustment at the rear LCA mount which is nice as it is relatively easy to get to. Camber is adjusted at the UCA.

[mike223]

Craig gives a good description on the Tbird IRS - bottom line is that once the alignment is in - it all "is where it is".

I practically drove myself cross eyed looking at all the frame diagonals, marking centerline on frame, running strings, measuring tape, laser levels...

I decided to build it as straight as possible - and if I decided it wasn't "straight enough" I would have to be able to put my finger on exactly where to cut + weld.

I finally reached the conclusion it was "straight enough".


Off the top of my head, I recall I had to use the spacers to locate the lower control arms (almost) as far rearward as possible - probably 1 spacer / washer short of as far rear as possible - due to (front of) control arms uncomfortably close to rear of frame in that area.

So I don't think you have much control of "wheelbase" without getting out the saw + welder.


Regarding rear track width - I'd recommend getting it all put together "straight + aligned" and then use wheel adapters to make it up - should be plenty of room - I actually got cute using 4.25 x 5 to 4.5 x 5 wheel adapters so I didn't have to source 4.5 x 5 hubs or rotors - the ones I'm using are 20mm thick and I'm still well inside the rear fenders with 315s (probably going to thicker spacers later to improve fender fit).

[grooml]

Thanks for the info.
After reading your posts I realize I'm kind or on the right track. I also figured on leaving the shims out until done, thinking the same thing, that the rod ends get further apart as you back them out. Anyone ever replace the washers with solid shims after all the dust was settled. As well, what's the lifespan of the rod ends(what we used to call heim joints). I was thinking of installing grease nipples. Bad idea? I also noted in another post that I have Wilwood 12.19 discs, and a drum brake for emergency/parking. I seem to be the only one so far that has this set up. I bought from M. Forte, and from what I've read he knows his stuff. But, the shimming out of the short axle hub concerns me. This was described in another post, so I won't bother you all with the details. Just trying to find someone else that has this set up with the T Bird IRS.
Thanks
Larry

[mike223]

Anyone ever replace the washers with solid shims after all the dust was settled.

I was thinking of installing grease nipples. Bad idea?

But, the shimming out of the short axle hub concerns me.

Just trying to find someone else that has this set up with the T Bird IRS.



Further thoughts:

I definitely at least considered making solid shims to replace the washers, can't remember if I did or not... But it reminded me of something else you need to watch for.

Watch the clearance between the spring mounts at the bottom of the coilovers and the LCAs - I had to make custom shims there - the shims provided would allow the shock (spring perch) to bind up against the LCA, I forget which "end of travel" it was at (maybe both) - but you can adjust that out of it with carefully made shims (adjust position of coilover in the frame / LCA mounts using shims) - DO NOT "just mount them in the center and call them good" - test carefully through full range of travel.


Next - I would not recommend drilling the heims for grease fittings - a real bad place for a catastrophic failure.


Regarding "shimming" the axle hub, I was talking about these that actually attach to the hub with lug nuts (sturdier than a "shim") - you might just want to remember that if you find you want them at a later date (use to adjust position of tires in fenders):

89683

[GoDadGo]

Further thoughts:

Regarding "shimming" the axle hub, I was talking about these that actually attach to the hub with lug nuts (sturdier than a "shim") - you might just want to remember that if you find you want them at a later date (use to adjust position of tires in fenders):

89683

F.Y.I.

The attached vendor has Hub-Centric options that may be a good choice if you need to scoot the rears out a bit:

http://www.ezaccessory.com/Hub_Centric_Wheel_Adapter_5_Lug_4_5_Mustang_p/5450-5450ht.htm