Jim McKee On Model 20 Rear Ends (Many posi cars have this ..)

Here is an Answer with a lot of great info on the model 20 rear end ...

Hi Mike,

I think you sent Nick to me with a question about SC/Rambler > rearends. Here is what I told him.> >

Hi Nick,

Roy Woods and Roger Penske Racing had no rearend failures racing AMC Model 20s in Trans Am in a five year period running multiple cars. I ran an IMSA RS car in the early 1970s with the same rearend for four years with no failures.
Unless your car runs faster than 11.0 second quarter mile times there is no reason to run anything other than a Model 20.

The stock keyed axles are only suitable for small street tires, E70 x 14 Polyglass or similar. Current street radials have greatly increased traction and are the limit on stock axles. Using drag radials and certainly slicks are virtually guaranteed to ruin the stock axles very quickly.

It all depends on how you intend to use the car. If your engine makes over 350 horsepower, even on street tires the Moser axles are very good insurance against spinning an axle and smashing the drum into the backing plate.
If you drive reasonably the stock axles have served many SC/Ramblers well, including my original SC/Rambler which now has 57,000+ miles on it. I might mention, I spun an axle sometime back. I have no faith in machining additional keyways or enlarging the single keyway, because then the hub cracks with the same results.

The factory service manual has valuable information for obtaining good service from stock Model 20 rearends. I just finished rebuilding two SC/Rambler rearend assemblies. Both got the following new parts; Moser axles,Timken bearings, positraction clutches, all seals, complete brake redo.

The 3.54 is my recommendation for a street/strip gear, because 70 mph is almost exactly 3500 rpm. Unless you mini tub the car you can't get large enough tires under a SC/Rambler to make use of the additional torque from the 3.73 or 3.91.
Stock SC/Ramblers usually run about 98 to 106 mph in the quarter mile which turns the engine about 5000 rpm. If your engine is capable of more rpm, then a lower rear gear ratio would need to be matched to allow maximum rpm at whatever mph the car will run at the end of the quarter mile.

The "Performance American" booklet shows how to weld the axle tubes to the housing and strengthen the spring perches. Those are the recommended modifications with the Moser axles to go as fast as 11.0 in the quarter mile. Current Moser axles use a Jeep axle bearing that will take all the abuse you can throw at it.

Talk to Rocky or Mike at Moser. Their axle studs fit AMC wheels very well and the whole kit comes with bearings, axles, inner and outer seals, and studs. Remember to remove the spacer in the center of the positraction unit to allow the axles to go all the way into the positraction clutches and plates.
Regards, Jim
PS; The Moser kit is over $200 less than the Mark Williams axle kit and you don't have to modify the emergency brake parts.

Nate Loban's Garage AMX SC/Rambler

Met up with Nathan Loban's Place near Albany NY

Was able to spend time chatting and seeing some very cool Drag AMX's ..
Very unexpected to see historical cars !!
Nice restorable Sc/Rambler with a suprise under the hood . Very hot 390 , running on VP racing fuel !!Love the smell of high octane in the morning !

Here is the goods ! !








Was a fun visit
Bob

Ken Usery's Sc/Rambler Convertible

Ken Usery's Sc/Rambler

Take a look at this beauty ! (For newbies . No , this is not factory stock . And not intendedto be .)
Top Quality All The Way ! Ken if you like , put your car story here ...

Flipping through the site and looking at these photo's of the "Convertible" Sc/rclone . And think about if back in 69 . They could of easily pulled off selling these !!!
This is really very nice ...













This is one beauty of a car , a ScRambler you can put the "top" down ! ! !

Sc/Rambler OEM Floor Mat carpet and trunk mat details

Hi All :

Would like to know what the original floor mats were , please send photo's and description if you can. Updated to include all the carpet and trunk mat info ...
Availability would be good to know also .
This question is awaiting an answer by an owner doing a restoration in progress ...

Thanks as always
Bob

Answer provided by Bill Strobel , here :

Floor mats or carpet, I will answer both.

Carpet, Cut pile, sewn (not molded) serge binding on the exposed edges. There have been some reports of original SC/Rs with loop carpet. Most notably Dan Curtis. All of the original cars I have seen have had the cut pile carpeting.

Floor mats.
The correct period rubber floor mats front and rear would be the individual front and rear (set of 4) that have a stylized car where the logo would go.
The early AMC ones had the R symbol and the 1970 and up had the AMARK symbol. But in the late 60s AMC produced mats with a stylized car where the logo usually goes. These are the only series of mats that can be found in the charcoal color. Bill

Trunk Mat : A series of e-mails from Bill here ...

There is one more floor mat used in the SC/R and that is the trunk mat.
Not ONE of the available reproductions is correct. The available reproductions are close to the color of the original material (aqua gray and black) but while the reproduction material is smooth the original material has a raised grain to it and is made of rubber. Bill

all of the late 60s AMC products used the same material. 1967-69 for sure maybe earlier and maybe into the early 70s.

The original material was not very durable. The NOS one I bought years ago is shelf worn from being folded in a box. Most of the ones in the cars just broke up and fell apart. I am sure it was just easier to screen print some felt backed vinyl that resembled the original stuff and at the time everyone just wanted something and that was close enough. The correct material would be expensive to reproduce. Bill

Will put where these might be found ....

Bob

HUSH THRUSH "CLASSIC" MUFFLERS Detail

Here is a detail on the hush thrush mufflers you can buy at Jegs etc etc ...



Here are pictures and a word on these is they are two inches shorter than the real deal ones that

are on the Sc/Rambler and a few other cars from the factory ...



Not sure , but the original hush thrush could of been dealer installed in some states . As the tomato can shape glass packs were too loud for those states sound ordinances ??

Thanks a lot big brother !

The decal is also not factory from the 60's . The originals were painted and much more real-estate on the body of the muffler ...Will put up the correct ones to compare ...



Here are the new style ones :









Old style correct Hush Thrush coming along with the correct Tomato can one's .
you decide what you need .



Bob

Sc/Rambler Plug Wire Routing

This in by Mike Lewis :
The plug wiring seems to be straight forward. Total of seven looms with two being free (not mounted). One free loom also has five holes (one for the coil wire).

Q & A clutch assembly

Q: I bought one of the aftermarket clutch forks for my SCRambler and it doesn't fit properly. Installed, it drags on the bottom of the bellhousing slot! The fork is for a 67-70 amc bellhousing and T-10. Have you heard of this before?

A: I've since talked to Jeff Kennedy and he tells me that AMC issued a replacement fork around 1975 and it was not made correctly. All of todays reproduction forks, sold by all the vendors are stamped copies of the incorrect 1975 fork.

They all ride on the bottom of the bellhousing slot! Solution: find and use original OEM forks!!

The problem I've having with the reproduction fork, is wear and tear on the release bearing. It presses unevenly on the pressure plate tines (diaphram plate), causing the ballbearings to heat up due to the added rolling friction.
The bearing wears quickley and the grease is spun out all around the inside of the bellhousing.

When I press in the clutch pedal to the floor, I get an awful grinding sound and a vibration right up the clutch pedal. Three bearings now in 9000 miles. (three summers) . I shall take out the trans next week and put in my OEM fork along with a new bearing and see how things work.

Here is a write up on this subject by Jim McKee:

Hi Bob,

Replacing the Borg and Beck pressure plate with a diaphragm pressure plate is a good move. I have reinforced so many of the clutch linkage bellcranks bent from trying to overcome the locking action of Borg and Beck pressure plates I have lost count. The B & B pressure plates have rollers that jam the plate into the clutch disc increasing pressure as the rpm goes up. This is what bends the bellcrank trying to overcome this roller action.

It is the primary reason AMC T-10s are hard to shift at upper rpms with this style clutch.
I recommend the Hays Street/Strip diaphragm #40-111 and disc #33-610.
These bolt onto the stock flywheel with a 10 1/2" disc with 1 1/8" x 10 splines.

Be careful using Hay's supplied bolts, because I have had problems with the bolt's shoulder not allowing the diaphragm pressure plate to pull up tight to the stock flywheels, because most stock flywheel holes are not counterbored.

Hays tells me these clutches are good for up to 600 HP and 7000 rpm. Buy an AMC clutch alignment tool and use it. The plastic ones are $ 4.00 at Advance Auto Parts last time I bought one. Good price on this clutch at Summit. Read the Hay's directions.

The correct throwout bearing for diaphragm pressure plates has a rounded outside edge that contacts the diaphragm fingers. The flat face throwout bearings tend to dig into the diaphragm fingers.
I also find the throwout bearing collar that holds the bearing needs to be shortened some, usually about .15" to .20" to allow freeplay adjustment as the disc wears.

Use a carbide bit on a lathe, because the thing is hardened. The throwout fork end that the bellcrank to fork rod presses against needs to be forward of the mid-point of the boot opening.

Most times this rod length needs to be adjusted shorter. I take this opportunity to use a 3/8" bolt and a spherical bearing at the bellcrank end by grinding off the welded stud in the bellcrank that accepts the clutch adjustment rod.
There is usually just a tack weld on the back of the stud. Both ends of the new rod need to be 3/8" x 24 thread to use the stock AMC adjuster hex and nut.

As Gerry has discovered, throwout bearings need to contact the pressure plate fingers evenly or vibration , accelerated wear, and/or binding occur.

I believe Jeff Kennedy about the later year throwout forks being incorrect, but I have no experience with this issue.

When you go to the diaphragm clutch, I also recommend changing the front and rear transmission seals and using synthetic gear lubricant. There is no warm up period with this fluid and I have had good luck with all of the synthetic gearbox lubes. I don't use synthetic lube in the AMC positraction rear ends and recommend Valvoline 75-90WHigh performance lube for them. Regards, Jim

IMPORTANT Exhaust minutia details for Sc/R WANTED

Hey All :

A question has been asked about the factory OEM exhaust system .

Q: Was the right hand(pass) hanger that goes from the spring perch to hold the rear tail pipe
at the front . The same hanger used on the left drivers side of the car ?. Just reversed ???
This would cause the right tailpipe welded on bracket to be moved slightly ...

(Will look at my cars as soon as I can , but feed back would be great also)

Q: What was factory OEM for the nuts , washers etc . that hold the head pipe to the exhaust manifold . contains the donut also ...??

Q:Has there been any middle of run changes to the exhaust that you know of ??

Thanks I. A
Will look at my stuff here like I said also....
Bob