I have a bunch of junk parts now.This summer I was testing the car on a airport road when at 106mph on my g meter bang like a M-80 hang the f..k on.Everything from the motor back is broke.Opened up Rear end ring gear has chips pinion has chips bell housing cracked drive shaft just about in two pieces exhaust gone.

The only thing I could reuse is the 30 spline moser axles.

The question is were to start and what would be the most cost effective.I can do all the work so would like part numbers and some opinions.

I put the car in the garage and this is the first time I even thought about looking at it.

A week later my 225 Mercury Optimax outboard blew with 306 hours on it just out of warranty.

At least I feel good LOL.

 

Not sure what exactly broke first,but it doesn't sound like it was the rear.You wouldn't have gotten as far or as fast,if it was.Unfortunately,it got taken-out along the way.I would rebuild it.Like you said,you have the 30-spline Moser axles.Take a good look at the posi unit,or have someone service it.If that is fine,then all you need is gears.Take the whole rear apart,and clean the inside,to make sure all the debris is out.Check the bearings to see if they are OK,and make a list of what exactly is still good,and what is not.
I don't know if you have a trans-brake in the trans,but it sounds very similar to something that happened to a friend of mine.He had a trans-brake installed in his TH400 by the local trans "expert",who was supposedly a good friend of his.When he got the car back,he never actually drove it around to try it.He took it straight to the track.When he made a pass,he was flying along at 100+mph when he shifted into 3rd.When he shifted into 3rd,the trans locked-up,locking up the rear wheels,and sent him skidding all over the whole track.As he put it " I used all 9 lives to keep that car off the walls." A few people had mentioned that if the trans-brake was not installed properly,that exact thing could result.Turns out they were right.So much for friends that are experts.He had to redo the rear,the driveshaft,and the trans.

 

Nice to know about the trans-brake issue,but this trans did not have one.I think something let go in the transmission also.I felt lucky to be hear when the car stopped.Thanks 507olds I will go threw it and salvage what I can.

I was not satisfied with the Eaton clutch posi at the track.Car would dog track bad in water box.
Thinking of doing a spool this time.

Maybe beefed up I would like the Eaton ,it sure was nice on the street.

 

The clutches that come in the modern Eaton units are not as good as the originals from the 60's.The originals were a knurled steel plate.They can still be bought new.I install them in both new & old units,and shim them as tight as possible.The units that come out of the box now are better suited for the wife in her Escalade.You get about a days worth of good use at the track,unless you tune the unit.
Your other option is a Detroit Locker.A little clicky while cornering,but much better on the street than a spool.This is a coupler style unit,so no clutches to wear out.

 

Well here's a update the pinion sheared it was 27 spline.I have the 30 spline axles so I thought I had the 30 spline pinion?

The guy who did this also did not put in a Eaton posi he put what looks like a factory style posi.No wonder why he gave me no receipts.

Can I get the 30 spline pinion and carrier and 4.10 gears that will work in this type O housing?

Looks like this was about as strong as a factory posi yuck,no wonder it broke.
The Bearing# M86649
Race#M86610 these were in there have no idea what was in there?

Thanks in advance for the help.
Jim

 

I am curious to know what carrier was used,if the axles are 30-spline.The factory carriers were 28-spline,and 31-spline.
ALL of the O-axle gears,new & used,have a 27-spline pinion stem.

 

Looks like he welded up a carrier to the posi I will try and get some pic's so you can see.

 

Here's a pic of the posi not sure what it is?

 

That's the Ford carrier that Reider Racing was making,then bought by DTS.It is also the same carrier that SuperCars Unlimited sells.The ones that Jim & I sell are also the same,with a few machining differences.The units will work pretty good,regardless.What you have,should be the 31-spline version,if it's not the 28-spline.Is there anything else wrong with the carrier,other than that mark made by the pinion?I can only assume that it had Richmond gears in it,or were the GM gears?The only gears available for them now,are 3:42 & 3:90.Richmond discontinued the 4:10's,but once in awhile,you find a set for sale.

 

Hey Brian,

When you say "shim it as tight as possible" what are you referring to. I've been reading the AM and CSM quite a bit trying to increase my understanding of diffs.

It also says there is a critical tolerance between the gears that needs to be kept?

 

Inside the posi unit itself,there are shims behind the clutches.They are in there to place some preload on the clutches,but they are very vague.They could be shimmed tighter,to make a more aggresive posi unit,but still function nicely,quietly,and last a long time on the street.You can actually shim the clutches as much as possible,and remove the spring completely.

 

Cool! great info brian!

So, i guess i dont have these "shims" in my open unit? It appeared that everything was in good working order when i opened it up a week ago.

I was recently chatting with Jim about what route i plan on eventually going when i switch over to Posi. Is the easiest way just to replace the carrier if i want to keep my original gears and differential?

I was looking around and it seems that eaton makes one with the springs like you were just talking about. I think the P/N is 19557-010, but holy-geez are they expensive!

 

Yes,the Eatons & the Yukons have the clutches with the 4 coil springs.I don't really care for the clutches that come in those,but I reshim them,and they work pretty good for the majority.If it is a street/strip car,I take those clutches out,and install the original style knurled steel.
If you want to keep your existing ratio,then yes,just swap the open carrier for a posi.

 

Okay understood, so the "springs" in the new eaton type replace the S preload spring that i see in my factory drawings.

Cool stuff, is there a good book out there that i can read up on? Or is the CSM the way to go?

 

Is this comparable to a Eaton posi Strength and price?

The gears were 3.90 Richmond.

I want this to hold up for 2 times to the drag strip a year and 2000 miles of street driving.
Motor has 425TQ with a 10" Ultimate Converter Concepts 4400 flash.

 

I decided to go with a 9" Ford and cut my losses.This 8.5 type(O) 27 spline pinion 31 spline axle broke in three weeks behind a 355 pump gas motor.

This rear is awfully week to me.I would think it"s the cars 60 ft times that will tell if these rears will hold up IMHO.

Thanks for all the info 507OLDS.

 

wELL i HOPE YOU BUY A REAR 9" CENTER SECTION AND NOT A STOCK ONE WITH THE STOCK SHAFT 1.313 OR YOU WILL BE IN THE SAME BOAT AGAIN REAL SOON. i DO NOT EVEN BUILD 9"

If you do not use the pro cente...r than do not bother with it at all.

Problem here is Parts and install The unit is a street unit doing track work. Next who set the rear end parts up? Jim

 

Carrier is welded for the centering ring for the olds gear to center on the carrier with out it the ring is a floater and WILL FAIL for sure. We do not weld this ring all the way around - I feel it compromises the carrier integrity. This is NOT where your rear failed. Did you say the pinion broke? or did the nut vibrate lose causing the pinion to hit the carrier WHICH it surely did in the picture. Jim

 

The trac lock unit only has 200-300 pound springs for keeping clutches locked at low speed.

How much track time do you do compared to street time?

 

How old was this motor? Trans? Rear end? I have drag raced my muscle car for 15 years now and Never an issue... 12.0 nothign super fast but.... Confused at your dilemma sounds like a lot of mess for a 106 mph run. Speed should not have killed all those parts....More like assembly error. Unless the parts were original and tired

 

Monzaz

new motor
new trans
new rear about 2 yrs ago 14 passes on it and 2000 miles of street driving.

No 1/4 mile passes on rear with new motor though.

MPH should be in the 107-108 with my new converter.

 

$3300.00 now in rear ends and hoping I can keep together to enjoy.

This rear broke strictly on the street.The converter did flash 4800 or so and had 20% + slip.Maybe it was the sudden hit of that loose converter?

With a 355 I thought I could just use this rear end?I have no plans to run faster ever than 11.50's

 

Can I ask what is a "dog track"
Thx.

 

Goes sideways while spinning tires - two different diameter tires, even by 1/4 inch, could be a cause, or posi not shimmed enough causing slippage on one side.

 

Watch a dog ( actually most mammals) walk away from you, the hind quarters are off to one side, ie: not in a straight line behind the front legs.

 

Got it. Thx.

 

Your other option is a Detroit Locker.A little clicky while cornering,but much better on the street than a spool.This is a coupler style unit,so no clutches to wear out.[/QUOTE]

507OLDS,
I noticed you mention the Detroit locker. I have a 71 cutlass with what I am pretty positive is the original axle. I have been reading a lot of posts and from what I am gathering is that its the 10 bolt 8.5 non c clip. It has the cat ears on the bottom and appropriate cover. I am off in college right now but when I make it back home, next weekend hopefully, I am going to look it over closer and make sure. So all parts that would be for a corporate 8.5 10 bolt that has c clips should be able to be used in my 10 bolt 8.5 non c clip? The idea I have in my head is 3.73s on a Detroit. Is this possible? I built a 455 that should be putting out about 500hp or so and a built th 350 behind it and now trying to keep beefin it up the rest of the way back.
Thanks

 

Anything that will work with c-clips will work without c-clips