costpenn

Completed the 3:42 TO Limited Slip rear end conversion for the 72 442 vert 455 MT I'm building. Started with the original 2:73 SA open unit - dated coded 70th day of 1972. Was in pretty good condition - had never been out of the car but had been spray canned about 8 times. It appeared to me the cover had never been off - and boy what a stink when I first opened it up. Somewhere along the line the RH wheel bearing had been changed out, other wise was a solid run of the mill unit that served as a foundation for the conversion.

Breakdown of costs/parts involved will be added in a later post.

costpenn

Here's a list of everthing used in rebuilding this unit along with price and source. Of course, labor is costed for the "love" of it (meaning free!) as well as my long time friend's expertise in setting up the ring & pinion and incidentals like paint are not costed.


Rear Brake Hardware Kit




Rear Brake Shoes




Rear Wheel Cylinders New




Pressing Rear Wheel Bearings




Rear Wheel Seals




3:42 Ring & Pinion & Diff Rebuild Kit




Sway Bar Shims




Anti Spin Additive




Rear Axle Vent Valve




Rear Axle Bumper Kit




Rear Brake Lines (Stainless) Kit




Rear Trailing Bolt Kit




Sway Bar Bolt Kit




Various Rear End Decals




Posi Carrier - 2:73 & up - NOS?




Synthetic 80-140W Diff Oil




Rear Brake Adjuster Kit - Left




Rear Brake Adjuster Kit - Right




Rear Brake Hose (Rock Auto)




Rear Coil Spring Insulators




Rear Coil Springs




Rear Control Arm Bushing Set




Rear Drums




Rear Wheel Bearings





Total for all parts was 695.10

Ring & Pinion Kit from Motive included carrier and pinion bearins, pinion seal, ring gear bolts, crush sleeve and cover gasket

Finally, we stamped the tube with the TO - and yes, it will always be represented as such.

stlbluesbrother

Just noticed this post.

Alway interesting to see cost break down on restoration/builds. Thanks for sharing

Allan R

Beautiful job on the resto/rebuild. Looks like it just came from the factory. Nice cost breakdown, does it also include shipping?
I have my Series 11 posi ready to go, just haven't decided on the final ring/pinion. 3:08, 3:23 or 3:42. Unless I get a 455/400 to slide in it will probably be a 3:08 or 3:23

From the sounds of your original SA code date stamping your car was built just about a month before mine. What factory? Mine is Lansing.

Those the wheels going on it in the background? Looks a lot like Matador Red?

Econow

So I hear "posi" and "Limited slip". I a limited slip cheaper to do then a posi? Is it also easier to drive with the limited slip - cornering? I am interested in which one to add. Thoughts?????

Allan R

The two terms are interchangeable. The benefit of posi or limited slip is to provide power to both wheels when the normal drive wheel starts to 'slip' or break traction. When the traction equalizes or returns to normal, the clutches in the posi returns the normal drive wheel (right rear) to be the only one 'driving' or supplying power to move forward.
Is it easier to drive? When you need it, yes. For normal driving? no. Note: if you don't change the gear oil or additive at regular intervals as called for by maintenance cycles, the car will start 'chucking' when you turn sharp corners. (Kind of like a shuddering coming from the back end).

If you want a lot more info on the posi/limited slip? Get in touch with Monzaz or 507OLDS on this site. They are specialists.

FYI, cost factor? Depends on what you buy, from whom, used or new, and the type of application it will be used for.

monzaz

Limited slip is industry standard for traction to both the left and right rear differential. Ford Gm Or Mopar Amc etc.

Posi - Is a Chevy term given to their division to basically nickname limited slip

Sure grip would be Mopar limited slip

safety track is Pontiac's limited slip

ANTI SPIN - Is your Oldsmobile term for limited slip.

Twin Grip is AMC's term for limited slip


SO I hope this helps you understand how to use your terms and what they all stand for. Jim

J D

Econow

So there is only 2 types of rear ends "open diff " and " limited slip ". I thought there was a true " posi " that is always " locked " into both axles - like if you weld the spider gears for a demolition car.
Thanks Guys

Allan R

Actually there are 3 types of diffs (4 if you count a spooled solid axle). You know the 1st two. The third and most popular at the track is the 'locking' rear which will provide the 2 burnout streaks you're probably thinking of. Does the term 'Detroit Locker' come to mind? It's by far the most popular and well known.
From 'offroaders.com'

costpenn

Allan,

Thanks - coming from what I've seen of your car that's quite a compliment

1) Shipping is not included on all the parts costs. Looking back at my spreadsheet, I approximate 35-50 bucks more all in on the shipping if I apportion it correctly. It REALLY pays to make a master list of eveything you need (as much as possible) and order it at once - freight costs are getting to be a larger percentage of the total procurement cost.

2) VIN indicates mine is a Lansing car -was orginally sold new in Wisconsin.

3) The car is a code 65 Flame Orange/White top/White interior car. I've gone slightly brighter in the color - almost a Hemi Orange. The wheels are incorrect - they have the push on center caps. I wish I had a do over on that since everything else on the car (with the exception of the heads, and seat belts) will be the correct components for a 1972 442 vert 455 W25 4 spd non air car.

Allan R

What are your last 6 on the VIN? Mine is 208783 Built April 7, 1972.

Are you looking for 1972 coded seatbelts? I think I know someone who has a set. I'll check.

re: the wheels? I hear you. I'm one of those guys who believes a SS11 is a bolt on wheel center with argent wheel color, and SS111 are clip on with body color wheel. I have both styles; and at a quick glance you could miss the difference. If anyone wants to argue the point, I don't care anymore because it's been re-hashed to death - ad nauseum.

I know that most judges don't look too close at them, but it's nice to know that you've got the 'right' ones, even if everyone else 'doesn't know'. That make sense to you? FWIW? The clip on center caps have 1 redeeming feature the bolt ons don't. When you undo the wheel acorns, there is a high risk of damaging the finish on the side of the bolt on caps because of how close they sit to the nuts. Snap ons sit way higher and aren't affected that way.

However, Snap ons have an annoying habit of rattling when the spring trim ring inside comes loose. 6 of 1, half doz of the other.

Love your color combo BTW. It will look stunning when it's done.

costpenn

Allan, my VIN sequence number is 199185 do you have a way of determining the build date from this? Thank for the offer on the seat belts, but I'm OK with the ones I had in storage.

Allan R

Well it was just before my car was built. Taking an educated guess that the assembly line would produce about 6000 cars/week. I know my car was built on April 7/10 (started on Friday evening shift, completed on Monday morning shift). If I back count from there, your car would likely have been built around the fourth week in March 72.

Look on your cowl tag. At the bottom left cowl rivet there will be a code embossed there. Something like 03D. The first 2 numbers are the month it ws built, the letter corresponds to the week (A=1, B=2, C=3, D=4, E=5). Without having a broadcast card or build sheet for your car, that's the closest I can estimate for you. Can you post a pic of your cowl tag or find that info?

costpenn

Allan, next time I go see the car again I'll get that cowl code - it's been at the painter's for almost 8 months now. Thanks!!

Tony72Cutlass'S'

[QUOTE=costpenn;359819]Started with the original 2:73 SA open unit -QUOTE]

Joe,

I just realized we have the exact same diff, i have a SA 2.73 as well. Did you do the Posi installation and bearings and such yourself?

costpenn

[QUOTE=Tony72Cutlass'S';395133]Tony, I had a good friend in the Olds club who's an amazing machinist actually do the ring gear to pinion lash spacing/set up. The posi unit I bought for it was an NOS unit (the best deal I've had on this build) so it needed no work - I really cant tell you much about it. The carrier and axle bearings are pretty easy - It's really not that complicated - go for it!!

Joe

monzaz

Detroit locker is still a form of limited slip... Crude and archaic but it does release in turns so it is still in that category. Same as Power trax...still releases to relieve torsion in the axle shaft.

Full spool is a tube with splines that is what we use at the drag race tracks
Mini spool is dirt track racing cheap spool can still be run with c-clips
Both these unit never let the axles slip or release in turns the tire will take all the slippage in the turns cause a bark in the tires and a bit of binding in slow turns... Not great for stock axles and you will need c-clip eliminator kit for the FULL SPOOL or a housing end made for boltin axles like 10 bolt 8.5, Ford 9", Mopar 8 3/4 etc.

If you are 80% street and 20% drag race always go with the Limited slip / locker (detroit locker, power trax) for a better street drive. If you do more street driving and freeway, do not use the locker type...manners are not as good in these applications they are more for your weekend warrior driver type that like to look cool driving to the track and back.

Jim JD

monzaz

POSI - limited slip

There are many types of these units-
Eaton Performance - Clutch type Preload springs (always on and working)
Auburn Borg warner- Cone type Preload springs (always on and working)
Torsen / true trac- Helical Worm gear not preload inertial type unit (best for road racing type applications)
Eaton Gov lock Auto locker - Clutch type (works under load request) Locks and unlocks when needed uses centrifugal flyweight and ramp gear system.'
Works great for truck low speed operation towing plowing ice snow off road etc. (NOT DRAG RACING)
Traction Loc - clutch type - beveled preload clutch NO PRLOAD springs (used in dodge and jeep
trac lock - Clutch type 'S' spring type preload Ford and GM
Traction lock Clutch type 9" and 8" Ford clutches larger diameter BUT only on one side...??? beveled preload plate for clutch preload. It's Ford enough said.

Jim J D

507OLDS

Joe,
Looks good.Just curious why you chose to stamp it TO,and not TM,which is correct for the 3:42 posi?The TO code is correct for 3:73 posi,for 71-72.

costpenn

Brian I screwed up. I stamped the tube TM, then much later was finishing the detailing and had that brake drum sticker as part of the ILT kit and put it on there (It was the only one provided) and forgot it is a TM.

cdrod

I know this thread is over a year old, but I thought it better to continue an existing thread than to start new one since there is some good background info already in this thread.

I've been reading up on "limited slip" differentials and it seems that the torsen is better suited for everyday, street driving. Do they have a longer service life and less maintenance than the eaton or auburn units, and can you put one in an 8.5" corporate 10-bolt? I'm building a Cutlass daily driver - 350, TH200-4r, 3.42 rear gears. I guess you'd call it a resto-mod as I'm modernizing many systems during the restoration process. I've never driven a posi before, but I want long service life, and dependable performance. I don't want the back tires breaking loose in the rain either.