My 8.8 Rear Build

**Firebirdjones** · 06-28-2012, 06:51 PM

I had some pics up of axles, but photobucket conveniently removes them after a couple days.

Give me a little time tonight and I'll post some more. If you need them for later I think you can just save them before they are taken down??

***SMWS6TA*** · 07-11-2012, 09:04 PM

Some teaser pics....to let you know I am still working on it. I discovered a couple of minor set backs. Luckily I haven't tach weld anything yet and I can adjust. I'll explain more after I do the fix. Kinda hard to put into words right not so after I'm done with the adjustments I'll update.

So for know....

This new grind off section is from the tabs that hold the break lines in place. I had to grind them off in order to make those adjustments I mention above.

Here's one prior to removing

Don't get excited yet, just a mock up with the 10 bolt axles, these are not the axles I'm going to use.

Here's a test to see who's paying attention. What do you see here:

Hint it's a good reason I triple check everything and being somewhat a little anal before I do something permanent.

On more clue and advice. Those that try this on there own make sure you DO NOT THROW ANYTHING OUT until you have it done and running in the car. Never know when you need to take more measurements.

I'll wait to give answers to the test later

**Firebirdjones** · 07-12-2012, 05:49 AM

Tubes are too short?

Edit: I forgot about this, I should find some pictures.

***SMWS6TA*** · 07-12-2012, 08:25 AM

^^
Yes and no.

As they sit right now in mock up = yes.

Are they cut short = no. I have about 4" well inside the sleeves. So I can pull the drivers side out and still have a lot left over.

I knew something was off and I couldn't place my finger on it until last night when started mock up. All I have to say is Thank God for plumes.

I was able to get the pinon center off the 8.8 and off the 10 bolt housing I still have. I got to adjust my measurements for offset between the 2 rears so I have a true center reference point.

What was my mistake you ask? I didn't catch that the 8.8 offset is 1 1/8" to the passenger side while the 10 bolt off set is 1". But here's the part I'm not getting. Even with it being an 1/8" off between the 2 I see the drivers side being off at least an inch more.

Here's what I got back as a reply to my question from one of the guys that has done this:

ME

Got a few more questions.

What did you use for the center to base all measurements off of?

Do I use the center of the pinon from the 10 bolt and transfer the measurements to the 8.8?

I may have to make a drawling to show you what I mean.....

I ask because I used the stock axles from the 10 bolt to see just how close I was after I got everything mocked up. The drivers side axle was almost an 1 1/2 to far in. I'll load up a pic to show what I'm talking about.

His reply

No, the center of the pinion is not on the center of the axles. On my 8.8 the pinion is offset to the passenger side by 9/16" (this is a good thing since it makes the 8.8 fit in the car better - the 10-bolt has less offset so the 8.8 can have more clearance for the TA). The cast part of the housing is a better measuring point - on my rear the ends of the casting are 8 1/4" off of the axle center, 16 1/2" overall width. You can double check this by installing the carrier and the cross pin, then stick your tape down the tube until it hits the cross pin. Do that on both sides and you can get a reference point on the tubes that are equal length from the pin. If you are using c-clip axles the flange to flange length of the rear will be the axle length x 2 + 7/8" for the cross pin (that's the cross pin diameter on the 8.8, the 10-bolt is 3/4" I think). If your axles are 32" then your new flange-to-flange width will be 64 7/8". On my 10-bolt I measured 2 5/8" from axle flange to housing flange. So if you do the math you would have something like 29 3/8" from the edge of the cross pin to the housing end.

So I went back and checked the measurements of the housings and pinon off set for both. I came up with this

10 bolt

from center of the pinon to the outer edge of the passenger side housing is 7 7/16"
from center of the pinon to the outer edge of the drivers side housing is 8 7/16"

Total housing width is 15 7/8"

Pinon offset is 1" to the passenger side

8.8 rear

from center of the pinon to the outer edge of the passenger side housing is 7 3/4"
from center of the pinon to the outer edge of the drivers side housing is 8 7/8"

Total housing width is 16 1/2"

Pinon offset is 1 1/18" to the passenger side

The total length of the 10 bolt axle is 61 15/16".

On this part of his reply

The cast part of the housing is a better measuring point - on my rear the ends of the casting are 8 1/4" off of the axle center, 16 1/2" overall width. You can double check this by installing the carrier and the cross pin, then stick your tape down the tube until it hits the cross pin. Do that on both sides and you can get a reference point on the tubes that are equal length from the pin. If you are using c-clip axles the flange to flange length of the rear will be the axle length x 2 + 7/8" for the cross pin (that's the cross pin diameter on the 8.8, the 10-bolt is 3/4" I think). If your axles are 32" then your new flange-to-flange width will be 64 7/8". On my 10-bolt I measured 2 5/8" from axle flange to housing flange. So if you do the math you would have something like 29 3/8" from the edge of the cross pin to the housing end.

Is he getting the 64 7/8" by adding these measurements mark in yellow arrows?

Based on what he saying above I now have to measure out from the pin instead of the pinon offset?

For what I understand In need to:

Install the gear set and pin
Next subtract half the total diameter of the pin (7/8") from the 61 15/16" then divide by 2
then measure out from the pin to the housing flange and that will give me my true axle length for both sides? Correct?

(hope I write this correctly)

61 15/16 - 7/8" = 61 1/16"

61 1/16" / 2 = 30 15/16"

If you can figure out a simpler way or decipher what he said please do so. I'm kinda

at the moment. I think I'm over thinking this and need someone to look it over.

**Firebirdjones** · 07-12-2012, 09:20 AM

He is measuring from the differential cross pin to get his axle tube lengths on each side, which takes the pinion center out of the equation (can't use that anyway since they differ between each rear as you have found out).

To get the overall width after measuring both side in this manor you simply add the diameter of the cross pin.

Measure to the axle tube flange...

***SMWS6TA*** · 07-12-2012, 09:41 AM

I just got another reply and this almost seems a little easier to do with one exception.

Install the gear set next the axle tubes and brakes, then insert the 10 bolt axles and c clip. Now the axles act as a jig.

My one problem is that I have a 31 spine carrier and the axles are 28 spine.

**Firebirdjones** · 07-12-2012, 10:29 AM

I've never used the axles as a jig because even when the splines are engaged into the carrier, there is still a slight amount of play or movement from the axles.

The axle bearing in the housing end is what supports the other end of the axle and holds it firm, but if your axle tubes aren't welded in, the whole assembly will move around ever so slightly.

You could try it, but I can't promise anything.

I used a jig at a shop, where you slide a solid steel bar through the entire housing, and it's held in place with donuts that are clamped with the 3rd member housing caps. It's straight and solid when done this way.

***SMWS6TA*** · 07-13-2012, 03:16 PM

FBJ,

PM sent

**Firebirdjones** · 07-13-2012, 03:26 PM

Replied

**Supershafts** · 07-13-2012, 06:48 PM

Originally Posted by SMWS6TA

then insert the 10 bolt axles and c clip. Now the axles act as a jig.

This is what i was referring to earlier when i asked how are you going to hold this...

If you use the axle the rear will not be true, not even close. I fix this issue with everyone that does this on there own. They are usually shortening or adding new ends and they move and that's one weld at the end, what you're doing will move so much it won't even be funny.

You need a fixture specifically for holding the tubes true, it will center off the housing mains and then go thru the tubes and have ends that will go into the axle bearing and locate the tubes true, if you buy a cheap version you risk that it won't be strong enough to hold the tubes true when you weld them, and they will try and move.

.

***SMWS6TA*** · 07-13-2012, 06:57 PM

Originally Posted by Supershafts

This is what i was referring to earlier when i asked how are you going to hold this...

If you use the axle the rear will not be true, not even close. I fix this issue with everyone that does this on there own. They are usually shortening or adding new ends and they move and that's one weld at the end, what you're doing will move so much it won't even be funny.

You need a fixture specifically for holding the tubes true, it will center off the housing mains and then go thru the tubes and have ends that will go into the axle bearing and locate the tubes true, if you buy a cheap version you risk that it won't be strong enough to hold the tubes true when you weld them, and they will try and move.

.

This is the quote that I was referring to in post 66.

I've already decided not to try this for other reasons.

This image is from this thread:

http://triadfbody.com/forums/viewtop...er=asc&start=0

He mocked his up with the brakes assembled onto the axles, and that was what located his axle tubes inside the 8.8 for the proper width and centering of the 8.8 center section.

Then you can 'clock' the tubes without worrying about them sliding in/out.

**Supershafts** · 07-15-2012, 07:03 AM

Don't do that.... i'll bet those aren't straight and they'll probably go faster when they get checked and done right,

Welding a bracket, a simple shock bracket can and does move the tube, whenever you make a weld the encompasses the tube it's moving all over..

***SMWS6TA*** · 07-28-2012, 03:42 PM

Well here it is. All mapped out.

Waiting on welds. The guy that's welding it for me is going to make a jig to hold everything in place. Once it's done a little more fab work for the upper control arms and then some replacement parts and new axles...

**pajeff02** · 07-28-2012, 05:10 PM

Good to see you back on this. Thought you got lost in the mall or something...

***SMWS6TA*** · 07-28-2012, 05:19 PM

No not lost between mine and his family vacations and then getting back to work our schedules we had to move this to the back burner. Once it's all welded and I get the parts coming in it will pick up. I want this so bad to get done. Last time I went to the track I rode with a buddy that has 9" with 3:73 gears on 28" Mickey Thompson DRs. When he launched I swear if it wasn't for the seat belt I would have been in the T-top storage area.

***SMWS6TA*** · 08-06-2012, 07:24 PM

-------Update------

Just had the preliminary welds on the axle tubes done to today.

Some clean up grinds and a couple of more weld passes and it will be ready for the 2nd phase of mock up (modified ladderbar, aka see Spaz's rear setup)

It's been slow but it's moving along. No pics, I want to wait till the finish welds are done.

Overall I'm satisfied even though the progress seems slow as turtles screwing. Same ol situation, if it ain't money, it's time.

I've been holding out on posting the mapping of the final dimensions. Reason why is I'm waiting on getting everything back together and see if it all works. I don't want someone coping me and I find out I made a mistake and someone else get's hurt. So I'll wait till all testing is done and I'm sure I can't break it before I post them.

I have also been keeping a count on expenses. I left it at work so tomorrow I'll post them up.

**pajeff02** · 08-07-2012, 02:50 AM

By going with a ladder bar setup, you are eliminating the torque arm, correct? If this is the case, how will you be determining and setting pinion angle?

***SMWS6TA*** · 08-07-2012, 08:06 AM

Setting the pinon angle will be very similar as with a torque arm. Instead of one adjustment I'll have to make 2. The UCA's setup will be as double adjustable, the jam nuts will be loose until the pinon angle is set then tighten the jam nuts. If anything the pinon angle will stay at a constant angle when compared to the torque arm. T/A's flex while under load, where the ladder bar setup won't. From what I read, I could set the pinon to 0* and run with it. I'm still checking with a couple of sources about that last part. So I'll get back for sure.

Well here is a list of the parts for this build. I listed some extras to show there are options to brands. Some things will vary in price based on the options you choose to use. I'm trying to make it as strong as possible so somethings are overkill.

I know hard to read. For those that need a magnifying glass.

This is what I've already purchased:
Ford 8.8 from Explorer, slip-posi, 31 spline carrier with 4:10 gears - $500
Used 10 bolt - $60
Axle Sleeves (materials and labor, plus some clean up on 8.8) - $200
Tubing, 1.315" schedule 80, 2' (for upper control arms) - $16
Mong 355 U Joint - $18
8.8 Main Cap & Stud Kit - $27.50

On or awaiting to be order:

Moser 31 spline axles - $370
Richmond Ring & Pinon 4.10 GR, 30 Pinon Spline - $ 208 (I have to replace the pinon because I had damage the original on tear down. Unfortunately for me no one sells just a pinon.

)
Strange Eng. 8.8 Spool Bearings - Master Kit - $94 ( I could have gone cheaper looking for all that this has but it comes in one kit and makes my life easier)
C Clip Eliminators for GM 10 Bolt - $160 (this is extra and not required. I wanted them anyways so now is the best time to do it.)
And all of the little things on pic 2 come to around $216 (this is so I can fab up the upper control arms for the modified ladder bar setup. These could probably have been gotten for cheaper. I just used Rusty's because it list the prices and has good diagrams for links)

Spent so far: $822
Estimate Total cost*: $1870

* - Like I said above some things added to the cost while others can drop the cost. Main expense is the 8.8 housing you get. Mustang 8.8's can be found cheap but most come 28 spline axles. I went the Explorer route because I wanted a beefer rear and the Explorer usually comes with 31 spline carrier and axles. There are some that don't (not sure yet of those yrs). So you could get a 8.8 from a Mustang and stay with 28 spline axles and it would be a few $100's cheaper in this area. However if you want to upgrade to 31 spline you'll have to get a new carrier and axles.

Another area to save is ring & pinon - 1st don't destroy it like I did. 2nd - You have many options of gear ratio, brand, and spline count - too many to list all. Research what you want vs what will work. I was looking for Yukon R&P gears but it would have required me to change my yoke (mine is 30 pinon spline) in order to make the Yukon 4:11's (only could find 28 pinon spline) work. So I'm going with a Richmond 4:10, 30 pinon spline R&P. It's a little cheaper but still strong as hell and made in the USA.

C Clip eliminators - this is option only. However for some types of racing you'll need to do them.

Bearings, Cap, Spool - these items you can get from any auto parts store. I happen to be getting mine from Summit and Strange Eng.

8.8 Rear Cover (Option) - $149, If on a budget you could stay with the stock one that hopefully came with the rear. I choose to go with the Moser cover because it has the fill and drain plugs and it helps strengthen the rear where as the stock one just keeps the oil from leaking. Plus the Moser looks so much better

Two more things -

1) This build is not for a torque arm setup. That would require some more fab work to make a mount so that the torque arm can attach to the 8.8 housing. The mount would also need to be welded in a special way that it will bond and not crack due to the material that the housing is made of. There are a couple of plans on tech that can show you how to fab a mount up. Also there is one guy that will make his for around $50+shipping, but you will have to get it welded to the housing. If I had to guess the cost to pay for the welding to be done I'd say around $300-$400.

2) I didn't list was Powder Coating vs Painting the rear - After a few test runs and after I'm sure it's all solid I plan on getting it Powder Coated to give it a better look. You can always rattle can it. This is your choice and I don't consider it part of the cost because this is more for looks then function.

***SMWS6TA*** · 08-14-2012, 06:53 AM

update on last post.

After talking with Moser it seems I do not need the c clip eliminators because in order for 31 spline axles to work with 10 bolt tubes & keep my stock brake set up I'll need to change the axle housing ends to 9" housing ends. This will let me do both and it turns out it's a little cheaper on the wallet. A set cost $97 + shipping.

As soon as I get the new 9" housings weld up I'll be able to order axles

Parts are starting to roll in. This should start moving again once I get all the parts in until then I have to wait patiently on the big brown truck.