As per my other thread i need to fix/replace my 8.8" diff. Does anyone know if a diff from this will fit, or what would be involved?

Cheers

FORD 1978 LTD P6 351 9 INCH FMX FOR WRECKING - eBay, Passenger Vehicles, Cars, Cars, Bikes, Boats. (end time 07-Jul-10 14:04:05 AEST)

 

if anything you could use a diff from an 8.5-geared car, the 9" is an entirely different animal tho so no it won't work in your 8.8 axle.

 

The gear ratio is 8.5?? woweee.

CHeers mate.

 

Sure it will work, I replace my 8.8" with the entire 9" LS third member in my 83.

 

Several issues come to mind for your proposed swap. First is the overall width of the 9" axle assembly drum to drum. Second is the distance between the spring perches. Third is the 9" does not have provisions for the vehicle speed sensor (VSS). If the width and spring perch dimensions are a direct swap then you still face the issue of how to send a signal to the computer. If you have a manual transmission the VSS may not be as big an issue. If you have the E4OD transmission, it is critical.

I would recommend you fix your 8.8". It will most likely be less expensive in the long run.

 

mate, just ring supa f series spares in melbourne. thay have complete 9 inch conversions for $450. fairlane wont fit

 

His truck is a '91, it doesn't need the speed sensor in the rear except for the RABS, which I would recommend he disable, anyway. The trans speed sensor is on the transmission where the speedo cable goes in.

Ford trucks had 9-inch rear-ends thru about '82 or thereabouts, it would be an easier swap if you found one of those if you especially want a 9-inch, or another 8.8, which is just about as tough IMO. However, I understand you got what you got, and you need to get your truck back on the road.

So, as mentioned, you will need to see what is the measurement drum-to-drum. If it is correct or at least very close (like within an inch), then you just need to take the spring perches off of your 8.8 and weld them to the 9-inch. The LTD is going to have coil spring perches in place which must be replaced with your leaf spring perches.

The only other issue is hooking up the driveshaft, you will need to make sure that either your u-joint caps are the same size, or you and your parts guy can find or make one that will adapt your driveshaft to the LTD axle.

Wait, I just thought of another hurdle, I am not sure the LTD axles will have the same bolt circle as your truck? I think the car bolt circle is smaller, but I don't know for sure, be sure to measure that as well to see if your wheels will fit.

 

Good point, I missed the model year info. So that leaves one less item to figure out!

 

Thanks heaps man that sounds like a winner, ill call them tomorrow

 

Thanks guys for posting up your advice, it helps me alot, since i am a noob and all
If i can just replace the internal diff parts for a reasonable price, ill just do that, it sounds alot simpler.

 

I missed the link in his post, I thought he was talking about a 9" truck rear end replacing the 8.8" truck rear end.

 

Sure, disable the RABS, but next time his truck swap ends on the freeway cause he attempted a panic stop on wet and the rear brakes grrabbed way stronger than they should and the wheels locked up, will you pay for the repairs?

 

Ha ha ha, spoken like someone who has never panic-stopped one of these trucks *with* RABS. It sounds good in theory but in actual practice, RABS is s-c-a-r-y.

 

No the LTD won't work, but a 9 inch from a truck will and is a VERY easy and good upgrade, except for the RABS(rear anti-lock brake system) that system needs the speed sensor that is in the axle. However I have read that you can but not yet tried to use the speed sensor for your speedo which is in the tailhousing to also signal the RABS.

To do the switch to the 9 inch you will need the complete assembly from backing plate to backing plate and IIRC a conversion U-joint. Your 8.8 brakes are the same as 9 inch brakes accept for the backing plate, so all your current brake parts will just swap over. The conversion U-joint that I'm not sure you will need is one size for the driveline and another for the axle, wish I could remember but I'm sure someone here knows or you will see when you try.

 

Nope, spoken like someone who's done a 360 taking up three traffic lanes, this in a hydroboosted dually truck with the RABS fuse pulled out and no load in the bed - yup, that fuse went right back in. Personally I'm extremely happy with the way the RABS works, trucks stop great regardless of the load and I don't have to worry about trying to do threshold braking while dodging whatever caused me to jump on the brakes to begin with. Maybe your RABS is malfunctioning, I know the HCU can sometimes develop an internal leak which really messes things up...

In any case - simply disabling the RABS is really dangerous, and is also grounds for a lawsuit if you ever get into an accident where you're at fault. There are ways to safely bypass the RABS by retrofitting proportioning valves and such, but simply disabling it is a big non-no, unless you're running loaded heavy good 90% or the time.