I have a 88 F 150 2WD and I am changing it to 4WD. The 2WD has a 3.08 diff and I want to use the 4WD 3.55's My problem is I want to keep the 2WD's housing as it has all new brakes and ABS. The 4WD diff does not have ABS. Can I just swap ring gear from the 3.55 to the 3.08? What kind if trouble can I get into?

 

to swap the gears you will have to tear down the complete 3rd member
ring and pinion and new seals
will need to setup the gears just as a new setup
new crush sleeve and backlash
not easy and needs a couple special tools

 

What year is the 4wd axle? FYI.. All the trucks from this series had RABS.

 

The 4x4 axle is out of an 1986 F150. I assume it will be a different gear ratio than the 2WD

 

If the 86 axle is the same 8.8 rear end as the one you have now, you can swap gears, but there's a chance that 86 rear end is a 9 inch.

 

If you do swap gears, you don't need to use a new crush collar, I never do, its a real pain in the butt when using a new one. I never do it and never have a problem.

 

the crush sleeve sets the pinion pre-load, they are relatively cheap ($5.00)and hassle-free to install and set up compared to the headache and cost factor if it's not right

 

I know their cheap, I just find them a pain to crush, and I ve always been able to get the proper preload with the old one. Actually I think you will find that allot of people use the old one. On the show Extremem 4x4 they had a tech part where he rebuilt a diff, and showed how he reused the old crush collar. I have a new on in my tool box for a 8.8 sitting there, I'll mail it to ya! :-)

 

yes you can un-crush the old one, but why? you then need to go through the same process as installing a new one and its rather simple....a lot like setting pre-load on wheel bearings, doesn't take more than 10 min. to do it right, so why not??? just to save $5.00 and risk potential expensive repair ?? kind of like rebuilding and engine and using the old bearings...it'll probably work if it wasn't the bearings that failed, but who wants to go through the trouble, only to have to do it over.

 

Im not doing it to save $5, I just do it that way never had a problem.

 

I was down and looked at the 86 today. It has a 9" diff in her. So now a whole new question, do I stay with the 8.8 or swap to the 9"? I don't know what gear ratio the 9 has, probably not 3:08s as I don't think that was used back that far. I guess the issue is the 8.8 has all new brakes on it and also ABS. The 9 will probably need all new braakes but I suppose that stuff is inexpensive. I am told the 9 is better than the 8.8 but I am building a truck to cruise to work in the winter not a puller.

 

For what your doing, I would stick with the 8.8

 

the nine will have 350 gears that will match the front axle and abs bakes suck any way you will have to get a specail set of gears if you want to keep the abs and use a 8.8 that is weak they have major flaws the 9 is bulit proof and bakes are cheap

 

Why does ABS suck???????? It really doesn't.

 

How do you figure a 8.8 is weak, there are cars running well over 600hp and running in the 8's in the 1/4 with 8.8's, i would stick with the 8.8.