rarert

I have a 2013 GT with a 3.73 rearend. I'm wanting to change to a 3.35 or 3.31. However, I don't want to change ring and pinion each time. What years of Mustang has the 8.8 rearend where I could just swap the hoghead? Thanks.

Derf00

Why do you want to get a lower gear? most would prefer a 3.73 over anything else, especially a lower one.

All mustangs GT's from like 88 on use an 8.8 rear end. Any GT from 2005+ will be a direct swap.

And I don't understand your comment about swapping the ring/pinion each time. Are you planning on changing the gear seasonally? If you did, you'd have to swap both out every time because they both wear as a matched set to each other. If you don't you'll get major gear whine.

And I don't think they make a 3.35?

jRaskell

I would hazard a guess he meant 3.55, not 3.35.

And it would seem to me that swapping the hoghead would not only be more effort than swapping the gears, but it would even be more effort than just swapping the entire rear end.

rarert

I did mean 3.55. I thought changing the hoghead would be quicker than changing gears as I would always have to adjust backlash and press the pinion gear out each time. Or is that not a the method anymore? I'm 63 yrs old and haven't changed a rear end since I had my '65 GT350 many moons ago. I still do all the work on my cars, though.

Yes, normally, a 3.73 is ideal. I'm looking for better mileage and especially less spinning on the snow. This is my daily driver.

You said 2005 up is a direct swap. Are the earlier models not? What do you have to do to them to be able to swap.

Roy_R

I have a 3.55, give me your 3.73....mine is a 08 with 14k miles on it. You have to remove the pan-hard bar, shocks, springs and linkages to the rear diff...lots of work, but the I can finally have a reason to paint it!

hootie_john

Mileage increase will be minimal going to a 3.55 (or even 3.31) honestly. You're talking MAYBE 1-2MPG if you drove all highway, extended distances. If you're looking for increased traction, spend roughly the same money as a complete rearend assembly and buy a set of winter wheels with snow tires. This will yield the best traction improvement.

EDIT: you'd also have to purchase a tuner to correct the speedo each time you did the swap. Not a big deal, especially if you plan to do any mods to the car, but it is an increased expense, nontheless.

BrazenStang

It sounds like you are getting the 8.8" rear end mixed up with the 9" rear. The hoghead in a 9" rear could be removed and swapped relatively easily as one piece. The 8.8" rear has a solid "hoghead" section, and the ring gear needs to be removed separately from the pinion gear. Any gear changes for an 8.8" rear need to have the rear cover removed where the ring gear can be pulled from, and the pinion needs to be removed from the hoghead which is welded to the axle tubes. The 8.8" ring and pinion gear have been the same since 1986. However, in 2010 Ford changed the pinion bearing, so be mindful of that if doing a switch.

I don't know if there ever was a time where guys would keep multiple hogheads laying around and swap them out, but it sure as hell doesn't happen on the 8.8" rear, lol. Once you pick a set of gears you might as well stick with them.

Also, going from 3.73 to 3.55 is not a significant enough change to make a noticeable difference in fuel economy. You need to go to 3.31 to make it worth your time and money. Most guys only report about a 2 mpg difference when going from 3.31 to 3.73, so assume MAYBE a 1 mpg increase with 3.55. Doesn't seem worth it IMO.

outceltj

Get a tune from brenspeed or american muscle. Tell them what your after and I'd be willing to be you will get better gas mileage and save some money and time over a gear swap.

akdoggie

Nobody seems to of caught what the OP was saying. He wants less wheel spin and the 3:73 spin too much for his liking. It shouldn't be that bad with the TCS on, but to each driver, it is different. I went to 373's with a limited slip carrier. I love it, even in the snow, but I have an AT, so that makes it easy to drive in the winter. lol

Rarert...think back to the Chevy & Dodge rear ends. You had to pull everything out the back to do any work. That is what we have with the 7.5 and 8.8 Mustang rear ends. The only practical way to do what you want is to have a complete housing assembly, axles in, without brakes and switch it out. That requires a bit of work but it isn't bad. The cables for brakes won't be a problem. You just have to release the panhard bar, the mount bolts for the LCA's, the upper mount for the top of the differential housing, shocks and springs. The whole unit slides right out, and the new one right back in. Nothing big, maybe an hour or so on the lift, 2-3 on the floor. It depends on your equipment and how much you want to do this kind of change yearly. With a garage and a lift, I could see it being done. I think I would just find a set of gears I liked, and stick with those. I'm too old for this yearly type changes myself. lol

rarert

OK...Thanks for all the GREAT information. BrazenStang is right. I was thinking these were like the old 9" rearends. I didn't know it was such a pain. I guess some things about the 'good ole days' were 'good'!

I think I'll take hootie_john's advice and get winter tires. Thanks all for helping an old guy newbie get this straight. I'm a Mustang man forever! (My 14 yr old granddaughter is into cars with me and thinks she's going to get this 420hp, 6spd stick, 3.73 rearend beast when she turns 16! Yah, right...that's what every 16 yr old needs as a 1st car!) I don't know how to close this thread, but if someone does, let me know. Great forum!