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AMC 20 Spring Perch Mod Pics Wanted

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bob401 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote bob401 Quote  Post ReplyReply Direct Link To This Post Topic: AMC 20 Spring Perch Mod Pics Wanted
    Posted: Mar/08/2014 at 2:59am
My perches in my Gremlin have seen better days. I have heard of people adding metal that wraps completely around the axle to help the abuse from drag racing. Does anybody have pics of modified perches? Is something like this better? http://r.ebay.com/PWYHEi Its still a street car with maybe 400 hp, but my perches looked better before the trip to the track.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote AMXFSTBK390 Quote  Post ReplyReply Direct Link To This Post Posted: Mar/08/2014 at 1:52pm
The web site you asked us to refer to doesn't seem to exist.

www,generalspringkc,com offers leaf springs and perches for your Gremlin.

What comes to mind for a reinforced leaf spring perch, is to get a length of pipe with a inside diameter equal to the outside diameter of your axle tube. You would want it to be wider than the perches you are using, and cut the pipe in half. Weld the two pipe sections on your axle tube and then weld a perch on with the correct pinion angle. This would call for a larger diameter perch mount allowing for a stronger mount with more contact area. Welding technique is critical in avoiding warpage and getting good penetration.
Questions are powerful tools...what's in your toolbox?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote FuzzFace2 Quote  Post ReplyReply Direct Link To This Post Posted: Mar/08/2014 at 5:44pm
I took flat stock and welded it between perch & tube on both front & back sides. If the perchs were rusty and weak I would replace them first then brace.
I am running a 360/high stall manual valve body auto, 4.56, 28x9x15 M/T slicks & Cal-Trac's and feel they would be good for way more HP than I am pushing now.
Link to a larg picture of the brace
Dave ----
 
 
TSM = Technical Service Manual

75 Gremlin X v8 for sale
70 Javelin 360/auto drag car
70 Javelin 360/T5 Street car
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Post Options Post Options   Thanks (0) Thanks(0)   Quote bob401 Quote  Post ReplyReply Direct Link To This Post Posted: Mar/08/2014 at 8:45pm
Both great ideas...  I wish i was the welding type myself. it would make things much easier.

http://www.ebay.com/itm/Anti-Wrap-Leaf-Spring-Perch-Pair-AMC-20-/400624099586
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Post Options Post Options   Thanks (0) Thanks(0)   Quote FuzzFace2 Quote  Post ReplyReply Direct Link To This Post Posted: Mar/09/2014 at 2:48pm
Sorry about the bad link.
Other than the ebay link showing it is a normal perch that fits an AMC tube I dont see it being "anti-wrap"? How can it be?
The braces I did on my housing are not and can not keep the springs from wraping up. They are to keep the perches from folding because they are weak from years of rust etc. and when the springs do not wrap the next weak link shows up......bent stock weaken perchs.
After you do the braces on the perches and the springs can not wrap up where do you think the next weak link is??? Center section spinning on the tubes so when you weld the braces you weld the center housing to the tubes.
What is the next weak link? Dont know at this time but I have done everything I can think of at this time.
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TSM = Technical Service Manual

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70 Javelin 360/auto drag car
70 Javelin 360/T5 Street car
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Post Options Post Options   Thanks (0) Thanks(0)   Quote bob401 Quote  Post ReplyReply Direct Link To This Post Posted: Mar/09/2014 at 10:59pm
I just found out my car will run in the 12's, I maybe be able to tune and tweak about 3 more tenths at most. I should not really need anything serious, just upgraded. I was thinking of getting ebay ones because they are thicker than the OMIX ADA stuff, mine were most likely orig. I also don't have any fabrication connections. And I hate leaving my car anywhere other then my garage. So anything with fab and custom always becomes a pain for me. Heck car #1 for me is a Geo Metro I cant see taking my diff out and throwing it in the trunk of that.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote FuzzFace2 Quote  Post ReplyReply Direct Link To This Post Posted: Mar/10/2014 at 8:40am
Un-less your stock perches are thin from rust you can use them.
I did the tube welding & braces in my garage with a 110 volt MIG welder. Because I had to crank up the out put the duty cly. comes down so you weld for 5 min. let it cool 10 min.
It is always good to get new tools (welder) for the garage Wink
Dave ----
TSM = Technical Service Manual

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70 Javelin 360/auto drag car
70 Javelin 360/T5 Street car
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Post Options Post Options   Thanks (0) Thanks(0)   Quote amcenthusiast Quote  Post ReplyReply Direct Link To This Post Posted: Mar/10/2014 at 9:12am
Sorry but it's a sad thing to me because the rear axle mods shown in AMC's '72 publication named "Performance American Style" shows this mod, among others, but is otherwise not commonly made known as if the modifications in the AMC book are outdated?

or is it 'shunned'?

The Jeep people popularity pushed to get aftermarket hop up parts for AMC's 7 9/16" rear (commonly named 'model 15' & 'Dana 35') but those axles have recently become automatic candidates for swapping a Ford Explorer/Ranger diff... -I was reading last night just to brush up on it, checking the Jeep axle widths for an interchange with Grem/Hornet/Javelin rears and found one testimonial about the Ford Ranger differential that had spun it's center housting (up) because it only has two small welds to hold it onto the tubs... apparently worse than the AMC 7 9/16"

I don't have a copy of Performance American Style (I lost it but that's another story)

But if I recall correctly ...as I always do... uh huh yeah right... it shows to weld the center section on both sides to the axle tubes, how to fabricate gussets for the leaf spring mounts by bending a 1 1/4" wide 1/8" thick mild steel strap over the axle tube and welding it to the perches (and logically to the tubes) the book would necessarily prescribe such a strap so as it would not interfere with AMC torque links? and it shows how to do make the single to double keyway conversion for the two piece axle/hub assemblies.

I don't understand why the information is shunned/not widely broadcasted but I guess it's just another AMC thing we need to get over it right now! and make a sticky?

use 'search' feature for 'torque links' info? -they could be welded on also & fabbed for Jeeps by someone who actually understood some about chassis geometry (there's a lot to it actually and highly educated engineers design that stuff to have all the 'right' mounting points etc -knowing that makes it easy for me to recommend AMC's Performance American Style...

I'll be addding another hand drawn page to my website amcramblemarlin.1colony.com to show the rear axle mods AMC prescribed in '72... today?

thank you AMC Forum for tolerating my long winded posts






 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote FuzzFace2 Quote  Post ReplyReply Direct Link To This Post Posted: Mar/10/2014 at 9:54am
Originally posted by amcenthusiast amcenthusiast wrote:

Sorry but it's a sad thing to me because the rear axle mods shown in AMC's '72 publication named "Performance American Style" shows this mod, among others, but is otherwise not commonly made known as if the modifications in the AMC book are outdated?

or is it 'shunned'?

I don't have a copy of Performance American Style (I lost it but that's another story)

But if I recall correctly ...as I always do... uh huh yeah right... it shows to weld the center section on both sides to the axle tubes, how to fabricate gussets for the leaf spring mounts by bending a 1 1/4" wide 1/8" thick mild steel strap over the axle tube and welding it to the perches (and logically to the tubes) the book would necessarily prescribe such a strap so as it would not interfere with AMC torque links? and it shows how to do make the single to double keyway conversion for the two piece axle/hub assemblies.

I don't understand why the information is shunned/not widely broadcasted but I guess it's just another AMC thing we need to get over it right now! and make a sticky?

use 'search' feature for 'torque links' info? -they could be welded on also & fabbed for Jeeps by someone who actually understood some about chassis geometry (there's a lot to it actually and highly educated engineers design that stuff to have all the 'right' mounting points etc -knowing that makes it easy for me to recommend AMC's Performance American Style...

thank you AMC Forum for tolerating my long winded posts
I lost my copy as well so dont feel too bad. I am trying to remember what was in it but you know old age and all Ouch
 
I would say some of the information in it is outdated. Take the key way mod why do that when you can get stronger Moser axles?
The links only keep the spring from wraping up and causing wheel hop and that helps in the traction. Because you have better traction and the rear housing is trying to turn up ward you will find the next weak link.
 
When our cars were new I dont think the perches where that big an issue but maybe it was if it was pointed out in the book? Anyway now that the cars are older and the perches have had some time to weaken with rust I have seen where they have bent. This was on a Scrambler 390/4sp think running slicks. After seeing that is why I did the bracing of the perches just dont know if the strap needs to go over the top as the book shows?
 
Our tubes are pressed into the center section and 2 little welds on each tube. The welds are known not to be that good and why you weld the tubes to the center.
 
Does the book say anything about the ujoints & drive shaft beefing up?
I am running non-greasable joints and told the shop I was using the car for drag racing and to build the shaft to take it.
Car runs 13's with the 360 but everything should take more power with little or no up grading.
Dave ----
TSM = Technical Service Manual

75 Gremlin X v8 for sale
70 Javelin 360/auto drag car
70 Javelin 360/T5 Street car
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Post Options Post Options   Thanks (0) Thanks(0)   Quote White70JavelinSST Quote  Post ReplyReply Direct Link To This Post Posted: Mar/10/2014 at 11:18am

Is the center section of the AMC 20 cast iron?

If so, be cautious welding the steel tubes to the center section. Pre-heat and nickel filler material may be needed. Not the standard wire feed stuff.   I don't have my Performance American Style book in front of me (however I did not loose it) but IIRC there is mention how to do this procedure.
 
Armand
70 Javelin SST, second owner, purchased 1972
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