I am starting this thread to get the experiences of forum members and share with others on the fits of tires and wheel fits on F-1's using the Jag IFS in order to help others in process (there are a number of members that are in the build process with the Jag IFS in the bonus built trucks). I believe that the problems with tire/wheel fit up is not as challenging for the F-100 based on front fender wheel opening size and particularly the shape of the opening (somewhat trapazoidal). The F100 wheel opening shape I believe helps reduce the potential for the front tire rubbing when turning.
At the time of starting this thread I have only succeeded in getting driving experience with the Jag IFS on F-1's from one forum member, Randy-"rhooper". Who has been very helpful for me. I hope that he will chime in and relate his experience. Hopefully there are others who are driving theirs that I have missed and they will join in on this thread.
To recap methods of installation of the Jag in the F-1's. The basic choices are to soft mount or weld in (hard mount). In the soft mount method the original front and rear are mounts are used, normally the rear mount is bolted to the bottom of the frame rail and a front mount bracket is fabricated to get the assembled truck such that the jag front crossmember is level fore and aft. This sets the ability to get the front end alignment to adjust correctly. The other method is to weld in the Jag cross member. Welding in will allow the potential to further lower the final ride height.
In my case I wanted to run and purchased Wheel Vintique "gennie" wheels using the original F-1 hubcaps. I bought my wheels a number of years ago and bought 15" wheels, however, tire choices for 15" wheels are slowly going away. Others are going with 16" wheels which I am sure is a better way to go now.
There are a number of reasons that the Jag IFS is desirable one of which is that the track width on the front of the original donor car is 58.3" while the F-1 track width is 58.08", almost spot on. I did not originally understand that the 58.3 track width on the Jag was achieved with the original Jag wheels having an offset of 25mm or 1". This means that the centerline of the rim is spaced in toward the center of the car 1" further than the mounting face of the rim. Note that the F100 front track width is greater at 60" which is another reason that the F100 has more flexibility in developing more clearance for the tire to fender.
As I indicated earlier, by hard mounting the Jag, you can get a lower stance. My caution is that the lower the stance the greater the chance of having tire rubbing problems that may not be readily resolved by choices on tire/wheel. Others who go thru the experience with lower, weld in Jags, hopefully can offer their experiences. That said, none of us that have not put some miles on our trucks with the Jag IFS can answer the question of "what works". That includes myself right at this moment. What I can say is my set up today is not satisfactory. I am soft mounted with original stock springs with the front cross member 6" off the floor with 15" x 7" with a 3 3/4" back space rims and 235-70-R15 tires. They will rub. My assembled truck lower A arm is essentially level with the floor. I should note that I believe that my original springs are a bit tired when compared to the experience of others that installed new springs.
I have ordered and should receive today new rims with a 1" backspace vs. the current 1/4" backspace which will set my wheel in an additional 3/4" That is the maximum backspace available in my wheel normally made by Wheel Vintique. I am told my them that on a custom order I could get a maximum of 1/2" more backspace. The issue with higher backspace wheels will be a generic problem. Wheels with very high backspace will be expensive like Corvette wheels.


SO, WITH THIS AS A STARTING POINT I HOPE THAT OTHERS WILL JOIN IN AND OFFER THEIR EXPERIENCE/SOLUTIONS TO HELP OTHERS!

 

Here is a picture of my current set up (4/1/15) which does not work.

 

Bill,
Can you tell me what your front track measurement is from the outer tire cheek on one side to the outer tire cheek on the other? I want to compare to what I have now.

 

Dave,
A measurement that I do have (fenders installed) is that with the 1/4" offset,
The fat point of the tire is 3/4" from the outside edge of the fender. Taken by a carpenters square on the floor thru the centerline or highest point of the wheel opening.

 

Thanks, I mean tire to tire, far outside edge to far outside edge. I have no fenders on to reference

 

Dave,
Measures at 71 3/4" at the fat point top of tire. Note that camber and caster not set, toe in close. Note that I can't get the math to work via a calc. My calc says it should be 69.05" based on Jag data (track width 58.3 with 1" offset jag rims) and my tire width (9.25)at the fat part of the tire. I can not offer an explanation right now!

 

OK, I will have to double check but I would swear I was at 68 1/2". I will check later tonight.

 

What is the WMS to WMS on the Jag unit. I searched but didn't find anything

 

Basically the same as the 48-51 F1 straight axle. I measured it the other day along with a straight axle but cant remember the number off the top of my head. I think it was 58 1/2".

 

Assuming that wms is "wheel mount surface" I just happened to measure mine with the truck on my lift and wheels off (suspension on stops) and I got 59 1/2 ". It will be a bit more with the lower control arms level-weight on the suspension. That agrees reasonably well with the Jag track width of 58.3 since as I stated above, Jags had 1" offset rims such that you subtract 2" from my wms to wms measurement getting 57 1/2. My measurement should increase by of the order of 3/4" with the weight on the suspension. Using Jags #'s the wms to wms should be 60.3".

 

I just measured my front out side of tire to out side of tire 64"
This is 87 with stock wheels tires are Michelin p215/70r15
Just measured my f1 front axle wms to wms is 60"

 

measured again, 68 1/2" outside tire cheek to tire cheek with 235/60/15s on 15x7s with 4 3/4" backspace. This was during mockup.

 

My calculation if you have the stock 6" Jag rims with a 1" offset on the wheels it should be closer to 66 1/4". That said less is better in this case!

 

I put my engine today or I would take a wheel off, maybe tomorrow

 

Just measured my front end - 79 XJ12 stock wheels -Buick 426 Nailhead and auto trans setting on frame- 66 3/4 inches outside wheel to wheel - Michelin P215/70/R15 tires