Kerrmudgeon

He looks like quite a character! Great pic!

Jackfit

I have been fortunate to own the car for 45 of it's 49 years. 46,000 miles on it when I bought it from original owner. Now pushing 300,000 and 4 restorations, visits to 48 states and 15 European countries.

Not bad for a old sports car

Jack

Jackfit

Hi to all,

I made a quick ride to Easton, MA , where a good friend , Ed Johnson owns a home town service and repair shop .

Ed had graciously donated a late seventies corvette differential to my car. It has a 3:70 in it, but I will have that changed out by Gary Ramadei, of New Haven , CT , who is going to rebuild and tune it for me.

I will box it up and send it to him this week.

Here are few pictures of Ed and his good friend Bob, (owns a 63) who helped with the transfer. If you ever need mechanical work done just south of Boston, give Ed a call....508-238-9455

Ed & Bob in his shop



Here she is .....

AirborneSilva

You're getting a whole lot closer to late mid spring cruising

Jackfit

Last time was at the factory 49 years ago. I have sent off my drive shaft and half shafts for a professional balance and u-joints replacement. the drive shaft will be balanced with a new slip yoke that is needed. The old one had 300,000 miles on it ....

This is a local shop that deals with a lot of construction equipment and truck shafts. Shops are getting harder to find now.



Look at the size of the shaft next to my little guys




Update on car restoration....yes...it seems like it is turning into a restoration from just a stuck transmission plug.

Ed Johnson had donated a 78 rear with the good Eaton Posi unit (it will be ) to me and I have just shipped it off to Gary Ramadei, who many know of for his rear end, TA and steering box rebuilding skills.

He is going to tune it, replace the clutches with metal ones, and put in 3:36 gears instead of the current 3;70. With my wide ratio Muncie , the car will be back to original gearing that I changed out in 1972 ish....

On the way to Gary Ramadei



When done, I will have replaced all rear suspension rubber bushings, strut rods , spring bushing, shaft balancing/joints, body mounts and bushings and maybe the throw out bearing ...mufflers and pipes...lets see...did I miss something.......

Jackfit

I had fun taking out my Muncie , I should have ducked , wrench fell, I moved to fast and forgot that I had no head room....

But it is out.....took about 2 hours no real problems , just lowered engine , as I moved tranny straight back, then raised engine and tranny fell forward and out...

Will replace throw out bearing (65,000 miles) last four years, and rear seal and bearing, to go with new slip yoke.

Jackfit

Update on rear end and suspension rebuild..

Gary Ramadei is rebuilding the 78 rear end that Ed Johnson donated to the project. Here are some pictures of his inspection and comments.

"Looks like this came out of a 79 vette. The gear date is Aug 1978, maybe it made it into a later 78? Doesn't matter the 78 & 79's were ok but did have some areas that were weak. The clutches, ring gear bolts, and axles were bad and this one is typical as it has all those bad parts. They are not going to be reused though, I will use the best parts and that will make a difference. The axles had 065-070 endplay and were mushroomed over. These are just good for cores now. There were no broken snowflake clutches so that means this diff wasn't beat on much, otherwise they would be broken. The ring gear bolts used from 77-79 were junk. They stopped using lock washers and the bolts didn't have the shoulders like the older ones did. I will use ARP bolts, you can see them next to each other in the pictures."


Parts not being used.....



Disassemble rear


















I will post next the pictures of the posi unit being polished

Jackfit

Here are pictures of the posi case before polishing. Polishing is done to prevent cracks from forming.





Same case after polishing

6T5RUSH

Jack,

Gary is very thorough in his work AND he keeps you informed all along the way of just exactly what he's doing to your part.

Kudoos to you for hooking up with Gary.

Give him my regards!



Jim
In God We Trust!

Jackfit

We are reworking a 78 Corvette Rear from 3:70 to 3:36 , plus tuning it.

Gary is doing the rebuild and here is a quote from him on bolts that attach the Ring gear.

"Here I countersunk the posi case ring gear holes. You see in picture#1 that the holes are square edged and the stock bolts work with that but not the ARP's. The ARP's have a larger radius under the head for more strength and have the shoulder on them like the old GM bolts did. Somewhere around 1977 they changed to the bolts that were in here before, shorter, no shoulder, and not loctited in place. Not good, many backed out in use sometimes within the factory warranty period. QC with the late 70's vettes wasn't as good as the earlier cars but that is probably the case with most lines of the period."

Stock bolts vs ARP's Stock on right



Before milling notice flat surface



Counter sink



Cut



Polish



Perfect fit

Jackfit

Gary is now assembling the posi unit after polishing.

Here is his commentary on the process.

Here I radiused the spider teeth to prepare to tune them. I used new solid steel clutches, new cross shaft, retainers, and washers. Next up the tuning process starts. Unlike a stock posi, where the spider lash is set between 002-008" and then the plates and springs are stuffed in there, I will set the posi up to a balanced, much more precise unit then any stock or rebuilt vette posi. where it is now I could just use the springs but it really works better to put the time and machine work in to tune them.


Pictures Parts laid out



Cross shaft and steel clutches





Radius Spider Teeth





Ready to Tune



Next series will be the tuning

Jack

Jackfit

Gary is now ready to tune the posi unit. Here is his explanation of the process.

"Here I started to tune the posi. While some think you just remove the springs and plates and bolt it together, there is much more to it. The process requires running in the new clutches to "seat" them. This will change the lash after about 50 rev's but I go at least 300 per side, CW & CCW. Then check it on the bench fixture and re-shim. The shims come in 005 increments so I grind them to within 001" to dial in the tune. The end result is a balance setup between both the Left & Right sides. The naysayers will tell you it will not work, yet Tom's has been building them like this for over 40 years for street, strip, and road race cars. You will have full posi action yet there won't be any hammering in the corners and there is less load on the clutches. All my vettes are setup like this and work great."


Video of process

Just click on picture for video

Jackfit

Continuing the rebuild, we are now preparing the case . It must be cleaned both inside and out. Here are comments from Gary on this procedure.

"Here I worked on the housing, cover and pinion yoke. I finished blasting them to bare iron. Now most places will just shoot a cheap top coat of paint and call it done. I never liked that since once the car is in use that paint isn't going to last as long as it should. So I blast the parts to bare iron. Then Etch them for 30 minutes, rinse, blow dry, flame dry, cool, POR15 and then when just right shoot the top coat to mix with the POR15 and harden together. I'm waiting for the POR15 to setup now to shoot the top coat. Then I'm going home to fire up my 72 vette for a weekend ride!
"

Blasting first



Etching





Flame Dry



POR 15 Base coat



Final Coat





Interior Case Prep Next

Jackfit

We are now installing the gears after countersinking bolt holes and using new bolts. Gary's comments:

"Once I had the posi were I wanted it, I stoned the back of the new USA 336 ring gear and the posi flange. Then I cleaned the new ARP's in Acetone, same with the RG holes. I use alignment studs to keep the ring gear in place since it is a press fit on the case OD. I use #271 red on the ARP bolts, torque them and then check for full seating of the bolt and the ring gear. I'll let the Loctite set up at least 24 hours before applying any load to them."


Clean Bolts in Acetone



Tom's US Gear 3:36 to replace 3:70





Stone surfaces



Alignment Bolts



Torque Bolts





Check Fit



All Set Up

Jackfit

We are now working the inside of the case prior to installing gears and posi unit. Gary's comments:

"Hi Jack
Here I final prepped the housing. You can see there in the ready pictures the inside didn't look so good after etching and rinsing. It was really only minor surface rust but I cleaned it up good with a wire wheel.
The holes were all chased. The pad holes were bottom tapped and countersunk, this means a bottom tap was used to cut new threads to the bottom of the holes. The factory used a starter or plug tap and the bottom threads don't always get a full tap. The bolt may not fully engage the threads so I know now the hole is fully threaded beyond the length of the bolt. The reason to countersink the holes is to cut the lead- in thread to prevent it from pulling when the bolt is torqued. The same process used on head bolt holes. All the oil passage were brush, washed, and blown clean with compressed air."


Rusting Before picture



Wire Bush





Chase holes






Radius Edges






Cleaning bores



Cleaned and ready to go

Jackfit

We are putting in a drain plug which will make changing oil a 5 minute job. Gary's comments:

"Here I tapped the drain plug hole and fit the plug. With new gears you will have to heat cycle them the first 10 drives you make. Drive 25-30 minutes, no racing, get the diff hot. Stop and let it cool at least 1 hour. At 500 miles you drain the oil and add fresh. With this drain plug it will be a 10 minute job, just jack up the RR of the car , pull the wheel off, put your drain pan under the plug, remove the fill plug with a long extension and 5/8" 8 pt socket and drain the oil. Clean off the fines on the plug, put a little #2 permatex on the plug and snug it up. Add posi additive and pump in Lucas 85-140 gear oil, should take just under 2 qts. Seal plug and install- done."


Tap hole



Fit Magnetic Plug










Installed

Jackfit

We are now installing the pinion bearing. Gary's comments:

"Here I installed the new USA Timken pinion races in the housing"







Checking work

Jackfit

I had removed the transmission last week to both adjust the linkage and to replace the rear seal and bearing. I did not want to take the case apart and in one of the recent posts, John Z mention a tool that would allow you to change the seal and rear bearing while the tranny was still in the car. I located the tool on E-bay and although my tranny is out of the car, I left the shift on to show it can be done .

My old slip yoke had 300,000 miles on it and it shows it.



My new slip yoke and balanced drive shaft



The tool to extract the rear bearing , with seal removed



Close up of tool



Rear Bearing , the tool slides in just like a yoke



I use a hose clamp to compress flanges of tool , edges grab bearing



Use wrench to extract bearing , bolt pushes on tail shaft , pulling bearing



Bearing pulled out





Can be done with tranny in car and not taken apart

Jackfit

Gary Ramadei is putting the final touches on the rear end he is building for me. He discovered excess run out in the posi unit. Here are his comments and process to reduce run out to his specs.

Hi Jack,
So as I mentioned yesterday there was a wide range of lash in the setup. I wanted to see if it was in the gears or the posi case. I removed the ring gear from the posi and checked the bare posi in the housing. I checked a few places; the posi flange where the RG mounts, the case OD where the RG ID is press fit, and the flange OD. I found the case OD was good with only 001" or less runout in it but the flange had 006" runout and the flange OD had 008". The flange OD doesn't matter but the case OD & face do. I set the posi up in the lathe using a small 4 jaw chuck to dial in case OD as my reference. I dialed the case OD to less then 001" and rechecked the flange run out in the lathe and it was out 006". I faced the flange 005 in small passes and turned the flange OD. In the lathe they were both 0 but I knew it would open up in the housing because it will be referenced off the case bearings.

"I found the caps were loose on the bearing races and set them up to 001" gap. Then I installed the bare case and found the flange runout 002 which is good. The case OD is still 001 and the Flange OD is under 001". I was able to keep the case bearings installed without issue. The lash is now within 002-003 compared to 006 before. I couldn't do a pattern test because I have to let the Loctite setup on the RG bolts again. Next up I will check the pattern to see how it looks. I did radius the edges of the teeth on the RG, this is an old blueprinting trick.

I will see how the pattern looks on Monday."


This video is an example of what he did to my unit. Just click on it



Pictures







On milling machine



Caps

Jackfit

Here are more photos of the build of my rear end by Gary Ramadie and his comments on Pattern.

Hi Jack
Here is the pattern. Now what you will see is the pattern is center to toe, which is how these gears typically set up, unlike "textbook" patterns which are perfectly center on the tooth. What I go by is the pattern being equal in length and somewhat uniform. Attached you will see the Drive & Coast sides of the teeth plus the lapping pattern that is on the gear out of the box- which I call "new pattern". Some gears do not have this but US Gear always does and I like to reference it since it may show how the gear set was lapped. In this case you can see the pattern is center to toe as well only a little high. Setting up this gear set it followed "suit" and the Coast side is center to toe. You will se in my pictures the lengths are equal. Now even though these are final lapped they are never uniform from one tooth to the next. Some may show a full pattern, the next one may be center to toe. I have seen them with one tooth tapering high and the next tapering low. This is where a lot of guys get caught, it is a time consuming process because each pattern change requires break down, cleaning, reshimming, reassembly, then testing. Many cycles to dial them in. Different ratios setup differently but it call comes down to how they were machined and lapped to start. Some new patterns are center on the coast and center to toe on the drive. The rotation is smooth with no binding or noise using a handwheel setup.