8.8 rear axle questions
 

I just wanted to clarify which part of which axles I need to build. My understanding is miata outer cup, miata shaft, and tbird inner cup. In there anything specific about the tbird cup I need to look for?

Thanks

humm.... if you're using the Monster Miata axles that is incorrect.

you use Ford T-bird inner AND outer CV joints... the wheel hubs are re-broached by monster miata for the tbird CV to fit..

Also, you need to use the CV joints from the tbird 7.5 axles, the ones made for the 8.8 are too big they do not clear the miata shock. The 7.5 CVs fit and work just fine with the 8.8 diff, the joint itself is just made a bit smaller..

Oh Gabe I don't think that is right. I think the axles are the same for the 7.5 and the 8.8. At least they are in the parts catalogs for a 1995 T bird. You have options for with and with out ABS but both the non ABS 7.5 and non ABS 8.8 use the same shaft.

The trick to clearing the shock is using an audi boot. Details are half way down the page here: Jim and Jenna build diary, Miata LS1 Conversion: The 3rd half of the back half, 8.8 Ford axles in a Miata.

When I saw you stuffing the tbird boot in there I yelled at the screen wait there's a better way! :)

REALLY???? ok.. Well, when I had a conversation with Martin a while back when i decided to go with the 8.8, He gave me the part number for the A1 Cardone axle for the 7.5... I interpreted that he said to make sure i buy the 7.5 CVs.. Which is what I bought. Until now i was certain it was a different part number for the 8.8 axle and the 7.5... oh well, no matter


just for the record though, i did not stuff the t-bird boot in there, I used the boots provided in the monster miata kit..

I have a set of the Audi boots to install one day because the Monster Miata kit boots will "balloon-up" at high speed & rub a hole in them. At least mine did.

Ditto I did the exact same thing with Martin and I was sure to order the 7.5 joints he gave me the part number on. It's when his boots looked like putting a 2 ton pig in a 1 ton stall did I start looking into it for myself. Turns out the cardone part number is the same for the V6, V8 and the super coupe for 1995 thus it crosses from 7.5 to 8.8 with the same axle.

I sent Martin that shaft info along with the part number and photos that are on my blog for the Audi boots. He called me and asked all about the boots, said they looked great and that he was going to try them and look at changing them in his kit. I passed on the chance to comment on his diff mount because he didn't ask and I couldn't find one good thing to say about it to keep the conversation positive.:sad2: Anyway you went down the exact same road I did a year later and got the same boots and shaft info as I did so probably no matter anyway.

Was the part number posted for the Audi boots or did I miss that?

Well not in so many words but I put a pretty good hint with a good shot of the box they came in on the blog...
https://www.v8miata.net/attachment.p...ine=1408651577

I got mine here and it's petty hard to beat for under 5 bucks...

Sweet, good info is the best!

Just for shits and giggles I decided to look up axles at advance auto parts.com

I looked up five cars

1996 thunderbird lx 3.8
1996 thunderbird lx 4.6

1995 thunderbird lx 3.8
1995 thunderbird sc 3.8
1995 thunderbird lx 4.6

I was expecting all the part numbers to match, but they don't.

These are advance tough one part numbers

All the 3.8 have axle part number ncv11995

All the 4.6 have axle part number ncv11998


The difference is abs, near as I can tell.


The a1cardone catalog also lists different numbers, as many as four different.

Cardone Mobile WEBCAT


Ok this is a pain, I hate comparing parts on a computer.....

I work at napa tomarrow, I'm gonna grab an axle book, and finally put this discussion to bed.

BY THE WAY - speaking of these axles..... did anyone else find it a HUGE PAIN IN THE A$S to get the outer CVs off these axles? I found the inside edge of the CV are just not made to make that retainer clip compress and squeeze back in... on both I banged for hours until the retainer clip finally shattered and the CV came off...

the other option is to cut the tbird shaft as close to the CV as possible, then you can take out the guts of the CV and pull the left over shaft peice out... but you risk damaging the CV joint which has to be well cleaned and repacked after....

Capital idea Chris! I'd like to know what the NAPA book says the differences are.

From what I found it totally depends on the manufacturer if they change the part number so my guess is they don't know either. Check this out.

This is the NAPA stuff and see the 957204, 957205 and 957206 numbers matches for both but the other one does not.

https://www.v8miata.net/attachment.p...ine=1408677216

This is from O Reillys Notice the FD8082 works on with all 3 engines and the other 2 show different numbers.

https://www.v8miata.net/attachment.p...ine=1408676532
https://www.v8miata.net/attachment.p...ine=1408676532
https://www.v8miata.net/attachment.p...ine=1408676532

Same with Rock auto. The one number matches and the other 2 don't.

http://i57.tinypic.com/2na0lea.jpg

So yeah they are all over the map but I'm pretty sure they are interchangeable. The axles from Martin are the same for both for what that's worth. For him to tell us to be sure to use the 7.5 there must have been a time he got burned on the 8.8s.


.

I'm hoping the book will have dimensions and spine counts, something more specific then part numbers. Let's hope the book as actually useful.

After removing the inner tripod joint & boot, remove the outer boot. Place the axle shaft with outer c/v joint attached into a 3 foot section of 2" diameter steel pipe. With one hand on the outer c/v splines & the other on the pipe (be sure that the pipe is in contact with the outer c/v joint). slam the open end of the pipe against the concrete. The axle shaft will fall right out. You're welcome. LOL!!

LOL Tbone you rock! Great info man.

It's been over a year now but I don't remember having any trouble. In fact I remembered thinking wow this is all that holds this together? As I recall I just put the shaft in the vice and knocked it off with a good smack of the hammer. I have to think after a few try's you probably hit it as hard as I did though.

Man, I'm glad I bought Martins complete 7.5 rearend kit with axles. That all sounds like a PIA.

I don't want to make Gabriel feel bad but it really wasn't a PITA for me. I did mine and changed both inner and outer tie rod ends on my steering rack on a week night so less than 3 hours.

I remember the tie rod part of the night well because the book said the inner tie rods should only be done by a qualified Mazda technician. So I ripped the Mazda logo off the front of the car, taped it to my shirt and voilà instant qualified Mazda technician!

Those were good days in the build for sure. :D

Yep, that's exactly how I did it... because that's the way the monster miata manual says to do it.... the one side i banged on the floor for about 5 minutes and it came out (retainer clip shattered), the second shaft i banged for over an hour and a half, my hands and arms hurt for the next day, and there's a hole in my concrete floor.... and of course, it also came out with the retainer clip shattered.... that was the biggest PITA of the entire project...

once out i studied the inner side of the CV joint where the retainer clip would bind, and it's not beveled at all... IMHO there is absolutely no way that clip could have ever compressed itself back inside the grove... i don't know if parts have slightly changed since you did it? but mine was next to impossible to take appart, and again, the clip shattered inside, on BOTH my shafts, so i had to take the entire CV apart clean it and repack...

I lol'd


On a sader note....

Napa does not have paper catalogs for cv axles.......... ...........

..........


And I work at the distribution center......... .........


.......


I miss the good ol days when you had the option of going through an entire isle of tech manuals to find a part....


I have another ace up my sleeve though...

I can try another couple stores I know for a catalog, or I know of an actual axle shop. That's all they do is axles. Surely they have a catalog...


Prolly be next week before I get to it though, I have to work again tonight.

If you find anything on CV's or axle bars, I'd sure like to see it.

This site:

Super Coupe Club of America

has some interesting manufacturer's specs.

Usually at about page 10, of the 91-93 model years, you can see some specifics of the axles. If you sift thru it, you can see that the 7.5 has smaller cv's than the 8.8. Rzeppa C2650 vs Rzeppa C4000. From the factory. You can also see the difference in axle length between 7.5 and 8.8, is less than 1/2", which could conceivably be compensated for by the plunge.

I'd be willing to bet that as the demand for these model specific axles declines, the aftermarket is supplying a one size fits all version, and that version has the smaller cv's.

Mike

Bummer on the manual. No big deal though just use 7.5 axles. No matter if they are the same as 8.8 or not you are covered then and I know mine and Gabriels are 7.5 axles in an 8.8 diff.

That's good to know. I stopped by that axle shop yesterday, kind of a waste, the guy barely knew what i was taking about. I guess they just specialize in driveshafts. He said he doesn't do much with cv axles excpet rebuilding them occasionally.

On the other hand, it was a nifty shop, lots of customer parts lying around, a lot of them look pretty well made. I'll prolly have to stop back again when it's time build the driveshaft...

You need to look for a machine or axle shop not a drive shaft shop. There is a shop in Sioux Falls that can do it but when I did the zillion hours of research on the matter it was clear it made no sense to reinvent the wheel. Martins stuff is good stuff that is competitively priced and you know will work. For me knowing it would work out of the box was reason enough to use his stuff. All you need is the shafts, spacers and hub exchange from him and a set of 7.5 tbird axles and you are in business.

That is correct, here's the part number from my rockauto purchase,




A-1 CARDONE

602023 (60-2023)

CV Half Shaft Assembly (8708.50.8900)

CAD$ 49.94

CAD$ 21.81

2

CAD$ 143.50

What are the spacers you are referring to Jim?

It's an aluminum ring about 1/2" thick that fits in the axle seal to take up the gap that is there from the Tbird axle being a little different size. You can see it about half way down my blog post here: Jim and Jenna build diary, Miata LS1 Conversion: The 3rd half of the back half, 8.8 Ford axles in a Miata.

So is the splined part of the shaft longer? That doesn't look like that seal is doing anything useful?

Exactly the splines are longer and that spacer makes up the difference. The seal still does it's job of keeping crud out of the bearing. Normally the Miata CV joint housing is right against the seal and the spacer fills the gap so the seal gets the surface it's suppose to. The inside of the spacer is tight to the tbird axle. I never really thought about it but I suppose eventually that seal surface would wear a bit on it.

Hmm, def an interesting setup. Didn't I see something somewhere, where they used miata shafts and outer knuckles and inner knuckles from the tbird?

I'm sure it's been done with a little creative welding and the thought certainly crossed my mind!

The shafts are pretty close to the same length. But since thery're not, the spacer acts to make sure the bearing is clamped when the axle nut is torqued, and to ensure that the CV housing doesn't contact the spindle body next to the seal, and to provide the same sealing surface as the Miata CV. It is a little more than a dust seal, it gets pretty cruddy back there. There's been some discussion over the years as to the importance of having that spacer made from steel versus aluminum. IMO since it does take the clamp forces, it should be steel.

The dimensions I use are: 2.205" OD, 1.25" ID, .220" thick. Chamfer the inner ID where it contacts the face of the CV. The OD is taken from the Miata CV seal surface, the thickness is the minimum to simulate the Miata CV; it could be longer, but any extra length takes away from the spline contact. The ID is just clearance to slip over the stub.

Mike

Maybe I can clear up a few items.
The remanufactured CV axles from A1Cardone are plentyfull and inexpensive.
Part # 60-2023 $ 65. Ea. with a core charge of $45 ea. I return the Miata CV axles in the A1 Cardone box. Never a problem.
I have had two Audi CV boots tear at the axle.I think the axle is too big. One had a clamp. The other did not. I continue to use the old style as they work great as long as you keep them clamped away from the shock! No ballooning Tom :-0
I burp the air out. Going on 100+K miles on the shop car.
The aluminum spacer is on its 22nd year with no problems.
Any axle that is welded or uses a Ford inner CV and a Miata outer is going to fail. Probably when you are a long way from home. I know of at least 30 axle failures and as many Miata CV failures. They just explode and that's it. lots of greasy pieces.
Hope this helps,
Martin

For the Monster application, the 60-2023 CV axle is the one you want for 7.5 and 8.8.
The outer 7.5 CV diameter is 3.5". The 8.8 is 4"
Both differentials have the exact same width and mount locations. One wonders why the need for two very similar Diffs. But don't get me started.

Well there you have it from the man himself!

For what it's worth I'm running Martins set up with the axles he lists above with an 8.8 and probably around 390hp at the wheels. Over the last 11,000 miles it has seen countless full throttle launches and romps past 100mph with no issues or signs at all of wear in his stuff. But I am running Audi boots so I'm going take a closer look at them tonight!

Side note to the core charge Summit's core it only $23 but I sold my Miata shafts with the rear end and came out as good if not better if you factor in return shipping of the cores. http://www.summitracing.com/parts/AAZ-60-2023/

Thanks for that Martin!

on a side note for anyone looking at this thread, i get an odd squeak coming from the outer CVs/wheel hub area... it happends on both sides, and ONLY once i drive it and get things warmed up back there... I lifted the rear of the car after warmed up and slow turn the wheels and you can hear it squeak... sound like a rubber squeegie sliding on a glass surface... didn't do this before the new hubs and axles...

this may be fine and normal, but i just want to make sure... i made sure when installing the aluminum spacers to apply a thin film of grease and that it was sitting properly inside the seal, as i noticied it would have been easy to overlook it and bend part the seal walls inside/under the spacer...

anyone esle experience this?

Hey guys, I'm building my axles right now and my clips shattered when taking apart tbird axles. What did y'all use to replace those retaining clips?

Axle clips
 

You can get those clips at Ford.
The CV needs to be cleaned out as the broken pieces will damage the CV
Cheers
Martin

Awesome thanks. I just finished taking them apart and cleaning. Local dealer says the part is discontinued and autozone and orileys didn't have a clue. I guess it's another puzzle to solve

I can send you some.Two?
PM me your address.
You owe me a stamp.
Martin

That's some awesome customer service :)

I'm in the process of installing a blower in my 92 which has a sbf. My car has the ford 7.5 irs rear. You think I will need to upgrade the 7.5 to an 8.8?

Power will be 400-420 rwhp

Recommendations?

You will never get enough traction to break the 7.5.

Thanks for the reply. Do you use the 7.5 or the 8.8?

Wow I just saw this! Thanks for the offer. I found some that did the job (hopefully!)

Wrong focus the weak link is not the 7.5 vs 8.8 it's the CV joints and shafts. Case in point...
https://www.v8miata.net/attachment.p...ine=1449684169

And power didn't do that time and stupid did. To answer your question no you don't need to upgrade but if you do PM me I'll buy your 7.5.

There is no question the 8.8 will take more power and punishment than a 7.5 but the bottom line is no one has ever broken either a 7.5 or 8.8 without the driver or the mechanic or both doing something stupid.

Thanks guys. So in light of the supercharger addition, what do yo recommend upgrading in the rear to try to stay a step ahead of breakage? What do you use and where can I get it..

Thanks!

Ahh... the driver. You could put 600hp to what you have easy if you never shock the driveline on sticky tires.

I would like to be able to use all the power it makes, and drive it to my full capability....Any axle upgrades available or recommended if I plan to drive it hard on sticky tires occasionally?

Well you have asked 3 times and gotten the same answer all 3 times and clearly that is not what you want to hear. If you are worried about it change it. 8.8s are not that expensive and I'll buy your 7.5.

if you're still having this issue jack up the back of the car and spin the wheel, spray some dry silicone on the cv boot. It won't last long but if it goes away you'll know that's what it is. I see it at work on front CV's often.

I think I've asked the question 3 times and gotten different answers but none that answer the question I'm asking. I guess I'm not asking the question correctly or I need to clarify....

I've been told it's the driver....drive it easy and it will hold 600hp

I also was told the 7.5 is plenty strong and the 8.8 is not needed, and I'm focusing on the wrong end....I need to focus on the axles, not the carrier.

I've been told the car won't get enough traction to worry about breaking

Respectfully, I'm asking the same question and getting different replies that don't answer my question. Let me expand on my intended use and driving style for the car. The car will be making over 400whp, and eventually 500-550. it Will be able to use the power and put it to the ground relatively well, and I do not plan to drive it easy. I want to be able to drive it to my fullest capability, which means right foot on the floor, never lift, kick the clutch and snatch a gear.

Can the 7.5 with upgrades in these light cars withstand 400whp for now and this driving style? If there are upgrades that can beef up the 7.5 to handle it, I'm interested to know what they are and where to get them. If I need a different rear, I'm interested in feedback on what other units may hold the power and driving style.

I'm very familiar with the 5 liter drive lines and the 8.8 solid axles having raced them for over 20 years....but have never owned a 7.5 IRS and know very little about the IRS so your personal experiences and recommendations are appreciated..

Joe