Projects Switching from 7.25" to 8" rear end,help

Howdy everyone,

So I gots a 65 Ranchero with a 200, 3spd, and a rear end that's getting worse. It's got a decent amount of play and I gots what sounds like crap dropping in the back when doing 50+mph (specifically on the passenger side). It's a 7.25" and I'm switching to a 8", out of a 66 Mustang. Is there anything I need to do (excluding brakes) other than drop out and drop in? Like driveline mods? Leaf spring adjustments? Crap like that. Please help, the noise is getting worse and it's my daily driver and the last thing I need is to have a bearing lock up on me and really leave me stranded.

Thanks guys!
Ryan

 

Also, are there any issues with keeping the 4 lug in the front and having 5 in the back, Other than keeping 2 spares? I just rebuilt the fricken front end and I aint doing that crap again for awhile.

 

I think your front end lug pattern is just an easy swap to hubs and drums with 5-lug? Not a Ford expert, but the V8 cars had the 5 lug, and I am sure the basic suspension is identical.

Since no direct experience swapping rearend in that vehicle, some general things to look out for. Perch width, is it the same? Pinion angle, needs to match the orig installation; you can get shims to adjust the angle. Total rearend width, the Mustang is probably close. Driveshaft length may or may not need modifications. Pinion U-joint may or may not match the driveshaft yoke size; but conversion U-joints are available. Shock mounts, are they on the U-bolt plates or rearend?

 

I believe your yokes will be different, that means a driveline modification for the new 8" yoke. Plus as mentioned check spring perch centers for compatibility before you start.

 

If the perches are slightly off, how can that be fixed, easliy?

 

Measure carefully, cut off and reweld. If your welding skills aren't up to par, any local welding shop can do it cheaply.
'66 Mustang rears are 57.25" wms to wms (wms = wheel mounting surface). It's a pretty simple swap. Shouldn't be too hard. As far as the front, do a search for '65 Ranchero 5 lug swap. There should be tons of into out there.

 

The front spindles are different for the 6-cylinder cars, in terms of how the backing plates mount, and the tie rod taper.

They are geometrically identical.

Scarebird makes a disc conversion that converts 4-to-5 in the process: https://scarebird.com/index.php?route=product/product&path=65&product_id=126

The Mustang parts needed to swap to 5-lug-drums and a pair of tie rod taper spacers are not exactly rare, or expensive.

 

This is true too. The 6-cylinder Falcon uses a diminutive 1210 u-joint. A custom driveshaft will need to be made.

 

Gimpyshotrods is right. I did this swap and there was "bastard" u-joint to be found to connect the 6 cyl driveshaft to the 8 inch rear. I ended up welding one up with another driveshaft that I had made that had the right tranny yoke on it. Other than that, the spring perch spacing between mustang and falcon were identical.

 

I did something similar when I did my V8 Pinto. The 1957-59 rear end pinched in perfectly. I did have to have the drive shaft cut down about 13 inches. I beefed up the front end slightly but was able to keep the front end as original with out going to larger hubs.

I think in your case, if you can use your drive shaft, may be, just may be, change out the u-joint and slightly trim your drive shaft to length.

 

This is something that if I go to a driveline shop then they can do it right? I don't have any welding stuff, nor a rear yoke for a 8".

 

Did you have to trim the driveline at all to make it fit or just cut off the yoke and replace with the 8" one? I have another driveline but it's set up for a FordOMatic and a 7.25 in the rear. Mine is a 3 spd man.

 

I had a fordomatic driveshaft. If I remember right the 8 inch was 3/4 - 1 closer to the tailshaft than the 7.5 was. I then did a V8 swap and had to start all over again. Sorry I can be of more help.

Sent from my SM-N920V using The H.A.M.B. mobile app

 

Can I drive in the meantime with 4 in the front and 5 in the back? Other than having to carry 2 different spares theres no issue right?

 

I put a Maverick 8" rear in a '77 Pinto cruiser wagon to take the power of a 5.0 and C-4 swap. Used the stock Pinto driveshaft with "bastardized" U-joints. Car still has the 4 lug front hubs and 5 lug rear. The 10" Maverick brakes worked fine with the front discs.

Sent from my SAMSUNG-SM-G930A using The H.A.M.B. mobile app

 

No issues. You'll be fine.

I ran a rock rig with 5-lugs on the front, and 8-lugs on the back for a long time.

 

A good shop should be able to modify the existing shaft to make this work. Worst case scenario, they would have to make a new shaft, with the requisite stuff on it.

 

Nice. I may do the disk conversion for the front since it's my daily and I also plan on getting power brakes as well so that'll work nicely.

 

Ouch on the worst case. What would you think a decent shop would charge to cut the rear yoke off and weld the 8" on? I tried calling a local one but they didn't answer. I'd like to know what is fair and what's a rip off, y'know.

 

Nice. What did you have to do to the u-joints?

 

Down here in Kalifornia last October I had the drive shaft for the 40 coupe made to go from a Turbo 350 GM to a Ford 8" and it was roughly $350 and change. I supplied the 350 yoke and they supplied the rest. They also balanced the whole completed assembly.

 

Oh crap, this might get expensive. So I have another driveline, the front is set up for a 2spd automatic and the back for the 7.25, can I flip the driveline and use my 3 spd man yoke on the small rear end side and the larger auto transmission yoke for the 8" rear end?

 

They should be able to make it for you. Just let them know you are on a budget and what you got to work with money wise. Definitely have new u-joints installed though

 

Balancing a drive shat can range from $75-$150. Depending on the shop and what they have to do to balance the shaft. It is money well spent. Cutting and changing the end maybe an hours time plus parts.

 

If memory serves me right, I used a pair of 1310BC u joints in it. Try www.driveshaftspecialists.com to see a list and pix of what's available. The "BC" joints have 2 different widths to match different yikes to the driveshaft.

Sent from my SAMSUNG-SM-G930A using The H.A.M.B. mobile app

 

I called them and the guy said $150 for cutting and welding the new 8" end on, I think that includes a balance. I'm hoping it does. I try to not let people know that I'm in a spot b/c that's when they take advantage of you. I'm 19, this is my daily, and I don't have a lot of cash b/c the car sucks it up.

 

That's a fair price.