• Welcome to The Truck Stop! We see you haven't REGISTERED yet.

    Your truck knowledge is missing!
    • Registration is FREE , all we need is your birthday and email. (We don't share ANY data with ANYONE)
    • We have tons of knowledge here for your diesel truck!
    • Post your own topics and reply to existing threads to help others out!
    • NO ADS! The site is fully functional and ad free!
    CLICK HERE TO REGISTER!

    Problems registering? Click here to contact us!

    Already registered, but need a PASSWORD RESET? CLICK HERE TO RESET YOUR PASSWORD!

I've decided to do a Cummin's conversion

Yeah it was an older F100. Thats the guy I bought mine from. His truck was bad ass. Ive done that swap and a 6bt and IMO go for the 6bt. Parts are more available........ect. I have a write on here on how to change out the AC bracket for the 88-00 trucks.
FT id be interested in your Fluid Damper. PM me details.
 
Well, I locked up a deal on a "new & shortened rear drive-shaft" as I have to move drive-train back to use the Cummins cooling fan & clutch assembly. Still working out if the front drive-shaft needs to be lengthened, or?

Motor mounts using 1st gen Cummins mounts will be from gmcuminsconversions.com and fabricated here in Florida

Once I get the 6.5 all dis-assembled I'll start removing un-necessary wiring from the engine bay/bonnet.

Needless to say it's a big project for my old beat-up bones but slow and sure like the 'ole bull' is the MO now.
 
Fleet pride in Tampa can retube your old shaft for you normally for under $150. I wouldnt reccomend shortening an oem shaft as GM used thin steel and packed them with cardboard for dampening. Are you trying to stick with your push button case still? Wasn't sure if it would even shift without ecm input for speed and gear from the j1850 data bus.
 
I would think, that if you are having to move the drivetrain back to clear the front of the motor, necessitating the need to get a shorter rear driveshaft (consider a new pinion angle to compensate for the different shaft angle from the shorter shaft), that you would have to lengthen the front driveshaft from the transfer case to the front differential accordingly (and also change the front differential pinion angle to maintain proper geometry) to make up for the drivetrain setback.
 
Husker6.5 said:
I would think, that if you are having to move the drivetrain back to clear the front of the motor, necessitating the need to get a shorter rear driveshaft (consider a new pinion angle to compensate for the different shaft angle from the shorter shaft), that you would have to lengthen the front driveshaft from the transfer case to the front differential accordingly (and also change the front differential pinion angle to maintain proper geometry) to make up for the drivetrain setback.
Click to expand...
I have considered shimming the rear pinion up, as for the front diff drive-shaft slip yoke type its in a straight line fixed position, I'll most likely do an SAS conversion later then I'd surely need to consider the front drive angles..
 
THEFERMANATOR said:
Fleet pride in Tampa can retube your old shaft for you normally for under $150. I wouldnt reccomend shortening an oem shaft as GM used thin steel and packed them with cardboard for dampening. Are you trying to stick with your push button case still? Wasn't sure if it would even shift without ecm input for speed and gear from the j1850 data bus.
Click to expand...
The seller stated the shaft was a new GM assembly he had shortened and balanced for his Suburban build. I'll be asking more questions about it.

That NP 246? Is still up in the air, I'll PM you about the NP you have gathering dust.
 
I've got a good 3.5" steel shaft with mine, not a thin wall oem shaft. Also keep in mind you have to relocate the torsion bar cross member when doing the cummins swap so you can move the transfer case rearward. I believe others have said you can go almost 3 inches back with it and still maintain enough torsion bar engagement into the lower control arms. As to pinion angle, if you keep the cummins crank centerline inline with the 6.5's, then you'll be fine. By moving it back you increase both angles equally, so your angles are fine(you're worried about the differential, not maintaing x angle at the pinion), you just want to maintain your 1-3 degrees greater angle at 5he diff than the transfer case to allow for torquing up of the pinion under load. An angle finder is a MUST here to make sure. And so long as you keep your cad on the front axle, the angles there are not that critical unless you plan on running in 4x4 at high speeds.
 
THEFERMANATOR said:
I've got a good 3.5" steel shaft with mine, not a thin wall oem shaft. Also keep in mind you have to relocate the torsion bar cross member when doing the cummins swap so you can move the transfer case rearward. I believe others have said you can go almost 3 inches back with it and still maintain enough torsion bar engagement into the lower control arms. As to pinion angle, if you keep the cummins crank centerline inline with the 6.5's, then you'll be fine. By moving it back you increase both angles equally, so your angles are fine(you're worried about the differential, not maintaing x angle at the pinion), you just want to maintain your 1-3 degrees greater angle at 5he diff than the transfer case to allow for torquing up of the pinion under load. An angle finder is a MUST here to make sure. And so long as you keep your cad on the front axle, the angles there are not that critical unless you plan on running in 4x4 at high speeds.
Click to expand...
I had not considered moving the torsion bar bracket, I'll need to examine this more.
 
n8in8or said:
This is starting to sound like a big hassle for you. Just think of all the trouble I could save you if you just gave me that 12 Valve so you are no longer burdened with the notion of doing a conversion. You're welcome. :smuggrin:
Click to expand...
Well, getting a handle on the task at hand will make thins less a hassle for me, I'm just not expecting to do it in a timely fashion...

I am considering moving the radiator into the support then reinforcing the support on the forward side and I will still be able to fit the Cummins CAC/IC too.
 
FellowTraveler said:
I find that I have to go back only 2.25" for my Cummin's fan & clutch to give good clearance so the torsion x-member will remain intact where it is.
Click to expand...
Every 4x4 retaining the ifs with a 12 valve swap I have seen or heard of required moving the torsion bar cross member. Don't think theres any avoiding it. It's not a huge deal, and is a good excuse to replace the bushings on the cross member(it's a FUN job to do with the trans and stuff in place, but a walk in the park with it and the crossmember out.
 
You must log in or register to reply here.
Back
Top