68 F100 SBFS build; CV, T45, DOHC/M122, Cobra IRS

[tylerb43]

Wow, great fab work and information. The collection of experts and knowledge on this site is just awesome! Keep up the great work, sir!

[SATURN5]

Thanks. I did manage to get the pass side all rebuilt over the weekend. New upper and lower balljoints and new inner tierod. Now to shove the truck over so I have room to do the driver's side.

[48prerunner]

Looks like you have a gt t-45? I have a cobra t-45 only diff is the tranny mount and speedo gear, different rear tailshaft. Anyhow any idea how close your transmission cross member lined up with the original f-100 one or holes in the frame? I'm trying to figure out where to make my speed holes in my boxed frame and trying to estimate where it will eend up without my motor.

[SATURN5]

I have two sets of holes in my frame, not sure which are the original ones since at one time, mine had a 350 Olds/350turbo combo. I just picked a set, made the crossmember as needed to fit.

I thought I had a 99 Cobra T45, I haven't seen what is different between the two. I know there is an early T45 that has the plastic gear on the tailshaft and the late with the encoder ring. Mine has the encoder ring.

[48prerunner]

Yeah you could have a 99 cobra t-45 only the early ones had a different mount.There is a number on an aluminum tag on a tail housing bolt. The 96-98 GT is a 1381-001 and the COBRA is tagged 1381-002 The 99-01 T-45 is tagged 1381-011. They are all the same spec just different speedo gears and mounts. can swap tail housings to change things.

The two holes I see in your pic of the frame where it shows shifter position over on the other ford truck forum look like stock ford holes. Would you have a pic of your cross member under the truck or know how far back it is from the second cross member by the cab mounts? Sorry for all the questions just trying to get as far ahead as I can so when my new motor gets here I don't eat up my warranty and I get to drive this thing before snow.

[SATURN5]

Yeah I can slide under and get you a measurement from the centerline of the cab mounts.

[elgemcdlf]

I am a bit curious as to your rear install. I see you went with welding the carriage solid to the frame. I had seen an install where they clipped the front mounts, mounted them to the frame & then welded them back to the carriage. They bolted with bushings but I thought it looked clean when finished. Is there a special reason you chose to do the front mounts the way you did?

On a side note do you think the guys at Ford sat back & said "let's do a IFS that everyone can use in old trucks with minimal work. We'll put it in the last of the RWD full size cars"?

[SATURN5]

I want/ed the truck to sit as low as I could. No special reason other the that, and it's just my solution to install it. Also, I did the IRS originally over 10 years ago, then got sidetracked with the SVO so the truck got kicked off to the side. No one back then was doing the MVIII/MN12 IRS, or at least it wasn't as well known, and there sure wasn't the kit available like today. Part of why it got kicked over was I had a Aerostar IFS semi installed and hated it. I didn't want to clip it, MII was costly option and the late CVIFS had yet to be discovered.... Glad I waited.

[elgemcdlf]

When I decided to do mine (IRS) there were a few published installs & Dave's kit did exist. I seen 1 install where they set the carriage inside the rails & had to cut away almost the entire rail for control arm clearance. As heavy as the carriage is the frame could actually be completely removed between the mount points if desired. My original plan was a MII variant with a Jag IRS. After doing some searching I found the CV IFS along with the MN12 IRS & decided that was the way to go expense wise.

In case you are not aware you can put a Trac Loc in from a 28 spline 8.8 with minimal work. The spyders (non Trac Loc) need a small groove cut into them for the lock ring on the axle ends. I had a machine shop cut mine. They didn't charge me but in fairness I know the guys. You can find a Trac Loc that actually came in the IRS but they are tough to find. At least I have never found 1.

Truck looks good. I am patiently waiting & watching as it comes together.

[SATURN5]

Super Coupes have the trac lok.

Also, no need to cut the grooves. Just remove the snap ring before installing the axles and you can use any trac lok. The rings are only needed for the original assembly to keep the axles from falling out while the chassis went down the assembly line. Mark VIII guys take em off, and I've done the same thing in my SVO, stick axle trak loc, Mark VIII axles, 99 Cobra IRS.

[elgemcdlf]

Super Coupes have the trac lok.

Also, no need to cut the grooves. Just remove the snap ring before installing the axles and you can use any trac lok. The rings are only needed for the original assembly to keep the axles from falling out while the chassis went down the assembly line. Mark VIII guys take em off, and I've done the same thing in my SVO, stick axle trak loc, Mark VIII axles, 99 Cobra IRS.

Something you may run into with no snap ring is the inner CV joint sliding in & out of the spyder instead of inside the cup. The inner CV joint is designed to allow the axle to slide in & out with suspension movement. Removing the snap ring leaves the window open to the splines doing the sliding instead of the actual joint.

[SATURN5]

Possibly. But dozens of Mark VIII and Super Coupe owners have run without the rings for years without any known issues being created. My 400HP SVO while only having a few thousand on NOS Mark VIII axles, also isn't showing any problems.

[SATURN5]

Got my steering adapted. A buddy donated a 03 Mustang steering shaft, and I picked up a 03 Mustang column to steal the u joint from. Cut the original fitting off the 75 auto column, and machined the end to match the late u joint for a nice factory spec parts collapsible steering.



He also donated a rack for lines, radiator with fan, and an entire 03 Mustang AC system. Even tossed in a ABS unit and lines.... which I'm not sure how well that would work...

[48prerunner]

I like the factory spec parts collapsible steering part saves the harpoon to the chest. I saw a 57 chevy at Carlise that had front end impact, guy bent the steering wheel almost in half said it gave him a few broken ribs. What does that have for the rack connection is it solid?

[SATURN5]

Stock rubber biscuit.

EDIT: Removed the biscuit and bolted it solid. The biscuit was flexing too much. Now I need to tear the column apart, the lower bearing is shot/gone.