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-   -   My caster mod (with pictures) (https://67-72chevytrucks.com/vboard/showthread.php?t=501241)

solidaxel 07-14-2015 04:28 PM

Re: My caster mod (with pictures)
 
Chevyrestroguy, Any updates on your truck!

crakarjax 07-19-2015 06:02 PM

Re: My caster mod (with pictures)
 
1 Attachment(s)
I'm mocking my parts up to do this mod but it looks like my lca only has .5" before it will hit the saddle during travel. Tons of space everywhere else, just the part of the lca that kicks out will be hitting. Has anyone run into this? The suspension is stock '72 so far.

crakarjax 07-19-2015 06:11 PM

Re: My caster mod (with pictures)
 
1 Attachment(s)
Another angle. This is slightly past stock bumpstop travel.

SCOTI 07-19-2015 06:52 PM

Re: My caster mod (with pictures)
 
Quote:

Originally Posted by crakarjax (Post 7246175)
I'm mocking my parts up to do this mod but it looks like my lca only has .5" before it will hit the saddle during travel. Tons of space everywhere else, just the part of the lca that kicks out will be hitting. Has anyone run into this? The suspension is stock '72 so far.

I shaved that inside portion of the arm to get clearance to allow moving the arm forward .750".

crakarjax 07-19-2015 11:56 PM

Re: My caster mod (with pictures)
 
Quote:

Originally Posted by SCOTI (Post 7246229)
I shaved that inside portion of the arm to get clearance to allow moving the arm forward .750".

Thanks, I guess I'll go for it. Trim until it fits seems to be the consensus in general...

crakarjax 07-20-2015 01:11 AM

Re: My caster mod (with pictures)
 
Ok I just went and tried to drill my cross-shaft... what kind of drill bit are you guys using? I didn't even make a dent. I have new TRW cross shafts and they seem to be made of a metallic form of diamond.

chevyrestoguy 07-20-2015 09:52 AM

Re: My caster mod (with pictures)
 
When I had mine done, I took them to a friend's machine shop and we chucked them up in a lathe and used a flat bottom carbide end mill. A local machine shop would not charge you much to do this. A standard hardware store drill bit set isn't hard enough to drill the hardened cross shaft. Plus, using a mill is much more precise because you can lock the shaft in the mill and get the new pin locations located exactly.

solidaxel 07-20-2015 09:56 AM

Re: My caster mod (with pictures)
 
So you trimmed the arm and not the cross member?

chevyrestoguy 07-20-2015 09:59 AM

Re: My caster mod (with pictures)
 
Quote:

Originally Posted by solidaxel (Post 7241092)
Chevyrestroguy, Any updates on your truck!

I have been working some insane hours for the past 6 months, but I have been working on the '64 whenever I have the time. I've gotten a lot of stuff done, mostly the tedious little jobs that drive you crazy. I'll post up progress pictures soon.

SCOTI 07-20-2015 10:59 AM

Re: My caster mod (with pictures)
 
Quote:

Originally Posted by solidaxel (Post 7247047)
So you trimmed the arm and not the cross member?

I did a little off both as I did not want to trim too much off the 'ear' of the arm.

I installed my modified arms & was able to achieve 100% suspension compression w/o contact but ultimately switched to Porterbuilt tubular arms for other reasons.

racecougar 07-20-2015 07:14 PM

Re: My caster mod (with pictures)
 
FYI, before you drill your new lower control arm shafts, verify that they match the stock hole position. Some aftermarket shafts come with the hole already moved a bit.

http://67-72chevytrucks.com/vboard/s...&postcount=237

crakarjax 07-21-2015 12:45 AM

Re: My caster mod (with pictures)
 
Quote:

Originally Posted by racecougar (Post 7248254)
FYI, before you drill your new lower control arm shafts, verify that they match the stock hole position. Some aftermarket shafts come with the hole already moved a bit.

http://67-72chevytrucks.com/vboard/s...&postcount=237

Thanks for the heads up, I did save one old shaft for reference so I'll check it out. One interesting thing I already noticed is that there's only one locating hole in the new shafts, because obviously only one is needed as stock.

That sucks that I can't drill the hole myself, I bought a set of reduced shank bits just for this purpose! What if I just angle grind a notch across the shaft? If I go the right depth it would still prevent the shaft from rotating.

SCOTI 07-21-2015 09:04 AM

Re: My caster mod (with pictures)
 
Quote:

Originally Posted by crakarjax (Post 7248642)
Thanks for the heads up, I did save one old shaft for reference so I'll check it out. One interesting thing I already noticed is that there's only one locating hole in the new shafts, because obviously only one is needed as stock.

That sucks that I can't drill the hole myself, I bought a set of reduced shank bits just for this purpose! What if I just angle grind a notch across the shaft? If I go the right depth it would still prevent the shaft from rotating.

The hole prevents fore/aft shift as well as moving in a L/R arc. A slot would only limit one of those twisting forces. Needs to be a drilled hole.

crakarjax 07-21-2015 11:28 AM

Re: My caster mod (with pictures)
 
If the locating nub is sitting flat on a flat surface of the shaft, the shaft won't spin without the u-bolts loosening significantly or the shaft rounding out. I can't see either of those happening without some other problems going on, and in those cases a rotating shaft would be the least of my worries!

SCOTI 07-21-2015 12:00 PM

Re: My caster mod (with pictures)
 
Quote:

Originally Posted by crakarjax (Post 7248933)
If the locating nub is sitting flat on a flat surface of the shaft, the shaft won't spin without the u-bolts loosening significantly or the shaft rounding out. I can't see either of those happening without some other problems going on, and in those cases a rotating shaft would be the least of my worries!

Then do it.
I'll stick w/doing it the way the engineers designed it. Seems safer to me.

crakarjax 07-22-2015 05:48 PM

Re: My caster mod (with pictures)
 
Quote:

Originally Posted by racecougar (Post 7248254)
FYI, before you drill your new lower control arm shafts, verify that they match the stock hole position. Some aftermarket shafts come with the hole already moved a bit.

http://67-72chevytrucks.com/vboard/s...&postcount=237

Thanks for this, my new shafts were drilled 1/4" further already! My question now is -- if I can go 1" should I? I see that most people go 3/4" over from stock, ofc there will be more trimming but it looks like I'll have room.

picklito 07-22-2015 06:06 PM

Quote:

Originally Posted by crakarjax (Post 7250515)
Thanks for this, my new shafts were drilled 1/4" further already!

Can you please post exactly what you bought? For a stock rebuild this is a great way to get a couple easy degrees. Thanks.
Posted via Mobile Device

racecougar 07-22-2015 06:15 PM

Re: My caster mod (with pictures)
 
Quote:

Originally Posted by picklito (Post 7250529)
Can you please post exactly what you bought? For a stock rebuild this is a great way to get a couple easy degrees. Thanks.
Posted via Mobile Device

The ones in the link I posted above are Mevotech brand. Part number MK6147 on RockAuto.

crakarjax 07-22-2015 06:19 PM

Re: My caster mod (with pictures)
 
Quote:

Originally Posted by racecougar (Post 7250540)
The ones in the link I posted above are Mevotech brand. Part number MK6147 on RockAuto.

Mine are TRW 13168A made in USA

picklito 07-22-2015 06:23 PM

Re: My caster mod (with pictures)
 
Thanks. I'd be interested to know how many degrees that adds.
Posted via Mobile Device

crakarjax 07-22-2015 11:22 PM

Re: My caster mod (with pictures)
 
Quote:

Originally Posted by picklito (Post 7250555)
Thanks. I'd be interested to know how many degrees that adds.
Posted via Mobile Device

Should be some basic geometry if you know the distance between the upper and lower balljoints, and the current angle.

Assuming 9" between ball joints and a currently vertical spindle,

3.14 * (4.5^2) = 64 (radius of a circle)

360 * (64 * .25) = 1.4 degrees (360 degrees in a circle times the fraction of the circle that is 1/4")

So 1" should net about 5.6*, 3/4" would be around 4.2* gain

crakarjax 07-28-2015 01:56 AM

Re: My caster mod (with pictures)
 
2 Attachment(s)
I ended up grinding a small flat in the shaft and then drilling with a 5/8" masonry bit. I noticed in the process that I didn't need to sink the hole in the shaft at all on the sides because the locating pin sits flush with the seats as they slope upward -- I think grinding flats for locating would work just fine considering this, since a sunk hole is actually just removing material that doesn't need to be there. Using a cap screw might be a different story though depending on the head depth.

gringoloco 07-28-2015 12:30 PM

Re: My caster mod (with pictures)
 
Anyone done this with CPP arms?

SCOTI 07-28-2015 01:57 PM

Re: My caster mod (with pictures)
 
Quote:

Originally Posted by gringoloco (Post 7256385)
Anyone done this with CPP arms?

I would measure CPP's vs OE. Seems like they do this from the start & why they can advertise 'improved geometry'.

gringoloco 07-29-2015 01:20 PM

Re: My caster mod (with pictures)
 
Quote:

Originally Posted by SCOTI (Post 7256491)
I would measure CPP's vs OE. Seems like they do this from the start & why they can advertise 'improved geometry'.

Research has led me to believe they gain caster via the uppers, which would pull the wheel back further.


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