Replacing the caged lower pulley bushings

pkwest

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I imagine everyone with the stock caged lower is going to need replace their bushings sooner than later. Others have done this by unscrewing the tribar (left hand threads). I tried this method but no way it would come apart even with excessive heat. This is the solution my friend/machinist brett at Nimmo Machine came up with. He is a genius, I really like how by removing three bolts I can insert new ones if needed again. He said the poly bushing material should be able to pushed in by hand. If it gives you trouble, two fender washers, a nut and a long bolt could be used to pull it into the hole. He torqued the bolts into his inserts to 40 ft lbs without loctite on the threads so I could remove them if needed. He said the rubber held the insert from turning when he tightened them. He did put a drop of penetrating loctite externally. He also made witness lines so I can verify they don't loosen.
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It required drilling out the original pins.
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I found the poly bushing material I used from a previous post on svtperformance. Do not use silicone as others have found out. It was said silicone cuts much easier. you don't want bushings that cut easily.
Abrasion-Resistant Polyurethane Rubber Round Tube
6" Long, 1-1/4" OD, 1/2" ID, 60A Durometer
mcmaster part number 87235K122
 

Albatross

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Well done! I have been doing a lot of research on this subject lately. I have a spare caged lower with worn out bushings that I wanted to replace in case the caged lower I am currently running goes bad. I definitely like the idea of not having to mess with the center bolt on the tribar. From the research I have done it seems the threads on it run the risk of stripping if they are siezed. Any chance you could get me some of those bolts and threaded inserts?
 

P49Y-CY

fomocomofo
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interesting solution. so what's to keep the insert from turning when you want to remove the bolt? it looks like it would spin? i am all for any kind of ideas for serviceable solutions for these things.

also just curious about when you attempted to remove the tribar with heat but were unsuccessful? how did you secure it?

thx and best of luck with this
 

cj428mach

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Seems like a lot of work for the stock tribar assembly. Have your machinest friend make a new tribar and drive assembly.
 

01yellercobra

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Nice fix. I should probably start keeping a closer eye on mine.

I really wish someone would come up with a splined drive set up to replace the threaded piece.
 

pkwest

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Nice fix, I work close to HB. Think he would renew my spare cages?
Maybe a vendor here could contact him about making a run of these. I dont have the time to get in the middle of this. I gave all this info to Russ at DivisonTwo who works on cobras and is also in costa mesa and uses Nimmo Machine.
 
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pkwest

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interesting solution. so what's to keep the insert from turning when you want to remove the bolt? it looks like it would spin? i am all for any kind of ideas for serviceable solutions for these things.

also just curious about when you attempted to remove the tribar with heat but were unsuccessful? how did you secure it?

thx and best of luck with this
tried what is described in this thread. Bringing the 4lb Caged lower back from the Dead?
 

pkwest

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interesting solution. so what's to keep the insert from turning when you want to remove the bolt? it looks like it would spin? i am all for any kind of ideas for serviceable solutions for these things.

also just curious about when you attempted to remove the tribar with heat but were unsuccessful? how did you secure it?

thx and best of luck with this
hopefully I won't need to put new ones in. If that day comes I'll let you know.
 

hotcobra03

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I did something like this using wheel studs pressed into tribar,
Than a solid threaded bar to make post.

It held up fine. Just finding rubber got more like work.

Those bolts your using. And barrel nuts is nice,,
But can't see how it will hold to tribar


Sad to ruin good pins.

I had no choice pins were beating pulley ,which also egged..

To get tribar to unscrew from Allen bolt is tricky,,
It's all in how you hold it,
And it's left hand threads ,
Not much different than removing from car.

I went metco.
 

pkwest

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I did something like this using wheel studs pressed into tribar,
Than a solid threaded bar to make post.

It held up fine. Just finding rubber got more like work.

Those bolts your using. And barrel nuts is nice,,
But can't see how it will hold to tribar


Sad to ruin good pins.

I had no choice pins were beating pulley ,which also egged..

To get tribar to unscrew from Allen bolt is tricky,,
It's all in how you hold it,
And it's left hand threads ,
Not much different than removing from car.

I went

I did something like this using wheel studs pressed into tribar,
Than a solid threaded bar to make post.

It held up fine. Just finding rubber got more like work.

Those bolts your using. And barrel nuts is nice,,
But can't see how it will hold to tribar


Sad to ruin good pins.

I had no choice pins were beating pulley ,which also egged..

To get tribar to unscrew from Allen bolt is tricky,,
It's all in how you hold it,
And it's left hand threads ,
Not much different than removing from car.

I went metco.
I didn't like the idea of the load the Metco puts on the nose of the crank. That is why I wanted to stay with the caged lower.
 

cj428mach

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@cj428mach Any chance of another run of the ones you used to make? Those were so nice!


No I don't think so, there is j2fab option now. It can handle a lot more power but is kind of overkill for some. I think there would be a market though as these cars as they age for an upgraded drive mechanism. Maybe a drive mechanism that would fit a stock lower but have an option for more pins/bushings or different connection for an larger than stock pulley.

If I finally twist mine off I'll look into as an option because Im like everyone else and not a fan of the owner of j2fab. Mine saw 29.2 psi a month or so ago before the aeroforce blanked out
 

Albatross

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I would like to find a capable machine shop near me to work with and try to come up with something on this. I have been looking all over the internet and have not come up with much. If anyone knows of a machine shop in or around Atlanta Georgia that has the knowledge and equipment to tackle something like this, please let me know.
 

P49Y-CY

fomocomofo
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i am determined to replace the rubber bushings myself, so i built a jig that will hold the tribar solidly while i attempt to unscrew the center post from it.

it is a 1/4" steel plate, 10x10, with a 7/8 hole in the center to access the center hex. three pressed-in dowel pins locate into the 3 holes on the tribar, and three small bolts gently keep the tribar pullled adjacent to the plate. the steel plate is bolted to 2 angle irons that are attached to a brick fire pit. i should be able to use a jack (similar to how i remove the whole assy from the car) if need be.

i will post up some pics

but my main question is, while looking at the assembly from the front (as if from the front of the car), what direction should i turn the center post in order to loosen it.? i'm 99% sure it's COUNTER-CLOCKWISE, since the center post threads into the tribar from the REAR.
 

MG0h3

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Man it’s been awhile but I believe you are correct. Which explains how they over tighten themselves

I just held one arm of the tribar in a vice. Could only get about 1/2” of it but it was enough.

I used some heat and PB blaster and it wasn’t too bad to get apart.


Sent from my iPhone using svtperformance.com
 

P49Y-CY

fomocomofo
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Man it’s been awhile but I believe you are correct. Which explains how they over tighten themselves

I just held one arm of the tribar in a vice. Could only get about 1/2” of it but it was enough.

I used some heat and PB blaster and it wasn’t too bad to get apart.


Sent from my iPhone using svtperformance.com

that's encouraging. some of the posts i have seen on this subject over the years said it was as hard or even harder to unscrew this than it was to break loose the whole assembly from the harmonic dampener, and that the threads can easily become damaged.
 

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