Changing out 7.5" rear to 8.8"

[agrich2]

I have a 99 Ranger 4x4 3.0L X-cab.
Suprisingly, I have a 3.73 7.5" ring/pinion in a 8.8" axle housing. Came stock and I am the original owner.
I have 190K on the truck and the rear end is starting to show signs of wear.
I am going to change all the rear differential parts and upgrade to an 8.8" 3.73 ring/pinion with all new spiders gears/bearings/seals...ect.
The main question is will I need a different carrier or will I be able to use what I have and bolt the 8.8 kit right to it???
Everything I read in the tech sections states it's a direct replacement.

Thanks,
Aden Rich

 

[06RangerXLT]

considering the 7.5 ring wont work in a 8.8 housing, id say get a new 8.8 housing.

dont mean to tell your incorrect, but theres really no other way.

check out a junk yard for a axle with 3.73. they are very common. im gonna guess you have a 8.8, (its a 4x4) and your thoughts on the ring being for a 7.5 is the part thats off.

 

[ZMan]

a 7.5" ring gear is 7.5", a 8.8" ring gear is 8.8"...they dont interchange. Now what DOES interchange is the outer axle bearings/seals, they are the same between a 7.5 rear and a 28 spline 8.8 rear (not to be confused with a 31 spline 8.8). When you buy the bearings and seals, just tell them its for a 7.5, or they WILL give you the wrong parts, its happened to me twice now.

 

[85_Ranger4x4]

a 7.5" ring gear is 7.5", a 8.8" ring gear is 8.8"...they dont interchange. Now what DOES interchange is the outer axle bearings/seals, they are the same between a 7.5 rear and a 28 spline 8.8 rear (not to be confused with a 31 spline 8.8). When you buy the bearings and seals, just tell them its for a 7.5, or they WILL give you the wrong parts, its happened to me twice now.

Axleshafts interchange between the 7.5 and 28 spline 8.8 as long as you stay in the same age range.

AFAIK the only thing that interchanges between a 28 spline 8.8 and what I would consider a real 8.8 (31 spline) is the ring and pinion and the differential cover. Carrier, axles, housing, bearings... all the other major stuff is different.

 

[adsm08]

I have a 3.73 7.5" ring/pinion in a 8.8" axle housing.

So is it just laying in the bottom of the housing or something? A 7.5 ring won't bolt to an 8.8 carrier and an 8.8 carrier won't fit right in a 7.5.

 

[agrich2]

Axle housing

I have a 7.5" in a 8.8" 10 bolt housing, I've checked the axle tag. I am going to go all 8.8" parts when I replace everything. So what everyone is saying is that I will need a 8.8" carrier for the spider gears and ring?

 

[Hahnsb2]

I have a 7.5" in a 8.8" 10 bolt housing, I've checked the axle tag. I am going to go all 8.8" parts when I replace everything. So what everyone is saying is that I will need a 8.8" carrier for the spider gears and ring?

You do not, it's not possible. If you'd read the replies in this thread you'd see you have a 28 spline 8.8, which shares the same axle shafts and axle bearings as a 7.5, unlike a 31 spline 8.8.

 

[adsm08]

How have you determined that this is a 7.5 ring gear? Do you have the carrier out already?

Have you tried to measure it with the carrier still installed? You can't get an accurate measurement that way.

 

[agrich2]

This is what my axle housing tags reads

It says I have a 7.5" 3.73 ration gearing, 28 spline axles. The main housing is in fact a 8.8" 10 bolt as I have taken it to a driveline shop and they have confirmed it as well. There is also several people at work with 4.0L rangers and I have looked at their rear axles and they have an identical housing.
The driveline guys say is was common to put a 3.73 7.5" setup in the 8.8" 10 bolt housing on fleet rigs with the 3.0L V6. I think my rig started it's life intending to be a drive around fleet rig. I AM THE ORIGINAL OWNER. I have driven this truck for about 188,500 miles out of the 189,000 it has on it.
MY MAIN QUESTION IS DO I NEED A NEW CARRIER????????

 

[ZMan]

believe whatever you want...I'll play along though. Yes, if you want to put an 8.8 ring gear in it you need a 8.8 carrier.

7.5s are 10-bolt as well, just so you know.

7.5

8.8

 

[Gotta_gofast]

It says I have a 7.5" 3.73 ration gearing, 28 spline axles. The main housing is in fact a 8.8" 10 bolt as I have taken it to a driveline shop and they have confirmed it as well. There is also several people at work with 4.0L rangers and I have looked at their rear axles and they have an identical housing.
The driveline guys say is was common to put a 3.73 7.5" setup in the 8.8" 10 bolt housing on fleet rigs with the 3.0L V6. I think my rig started it's life intending to be a drive around fleet rig. I AM THE ORIGINAL OWNER. I have driven this truck for about 188,500 miles out of the 189,000 it has on it.
MY MAIN QUESTION IS DO I NEED A NEW CARRIER????????

If this is true then someone has swapped an 8.8 into your truck or whoever built your truck labeled it as a 7.5" but installed an 8.8" off of the line.

Listen, whoever you are going to... they do not know ford vehicles. Do not ever go back there! THE 7.5 AND 8.8 DO NOT HAVE THE SAME CARRIER HOUSING.

To answer your question, yes you WILL need a new carrier. You will also need an 8.8 axle to put it into. lol

 

[ZMan]

If this is true then someone has swapped an 8.8 into your truck or whoever built your truck labeled it as a 7.5" but installed an 8.8" off of the line.

Listen, whoever you are going to... they do not know ford vehicles. Do not ever go back there! THE 7.5 AND 8.8 DO NOT HAVE THE SAME CARRIER HOUSING.

To answer your question, yes you WILL need a new carrier. You will also need an 8.8 axle to put it into. lol

Ive seen 8.8s installed in non 4.0 trucks from the factory...but they didnt put 7.5 guts in them. Lol.

Lets think about this for a minute..if you put a smaller ring gear in a large housing, how is the pinion gear going to contact it? It would have to be a custom pinion gear, why would ford do something stupid like that?

 

[85_Ranger4x4]

Some heavier GVW 3.0 trucks especially as time went on did sneak out with a 28 spline 8.8, which as mentioned before is similar in some ways to a 7.5.

Compare the diff cover shape with the earlier pics and take note of the shape of the cover, if it comes out as a 8.8 measure the axle tubes to confirm it is a 28 spline and you know all you need to know. 7.5/28spl 8.8's are 2.80" and 31 spline 8.8 is 3.25". It is improbable that somebody traded you axles in the dark of the night to get a 31 spline because they were not factory installed at all in '99 but that would eliminate all the variables.

http://www.therangerstation.com/tech_library/Axles.html

Lets think about this for a minute..if you put a smaller ring gear in a large housing, how is the pinion gear going to contact it? It would have to be a custom pinion gear, why would ford do something stupid like that?

Do not give them any ideas, they have done such barely thought out ideas before...

 

[Gotta_gofast]

Ford did throw 8.8 axles under some 3.0L models with 4x4, but he stated his build sticker shows a 7.5" part number.

Either way the guy is pretty stuborn. I wish I had a spare 8.8 carrier still, I would send it too him free + shipping just so that he can open it up and have one of two conclusions

1. It IS a 7.5" axle and he finds the 8.8 carrier and ring gear will never fit. He'll never get the pinion deep enough also.

2. It IS an 8.8" axle already and he just opened it up for no reason.

 

[Gotta_gofast]

Some heavier GVW 3.0 trucks especially as time went on did sneak out with a 28 spline 8.8, which as mentioned before is similar in some ways to a 7.5.

Compare the diff cover shape with the earlier pics and take note of the shape of the cover, if it comes out as a 8.8 measure the axle tubes to confirm it is a 28 spline and you know all you need to know. 7.5/28spl 8.8's are 2.80" and 31 spline 8.8 is 3.25". It is improbable that somebody traded you axles in the dark of the night to get a 31 spline because they were not factory installed at all in '99 but that would eliminate all the variables.

http://www.therangerstation.com/tech_library/Axles.html

You need to watch out for the axle tube dimensions as the 28 spline 8.8 shares the same axle tube diameter as the 7.5" axle. So no matter what axle he has (if it is factory) should have the 2 3/4OD axle tube.