My caster mod (with pictures)

[solidaxel]

Chevyrestroguy, Any updates on your truck!

[crakarjax]

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]

Another angle. This is slightly past stock bumpstop travel.

[SCOTI]

Originally Posted by crakarjax

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]

Originally Posted by SCOTI

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]

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]

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]

So you trimmed the arm and not the cross member?

[chevyrestoguy]

Originally Posted by solidaxel

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]

Originally Posted by solidaxel

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]

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]

Originally Posted by racecougar

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]

Originally Posted by crakarjax

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]

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]

Originally Posted by crakarjax

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]

Originally Posted by racecougar

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]

Originally Posted by crakarjax

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]

Originally Posted by picklito

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]

Originally Posted by racecougar

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

Mine are TRW 13168A made in USA

[picklito]

Thanks. I'd be interested to know how many degrees that adds.
Posted via Mobile Device

[crakarjax]

Originally Posted by picklito

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]

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]

Anyone done this with CPP arms?

[SCOTI]

Originally Posted by gringoloco

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]

Originally Posted by SCOTI

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.