CPP Drop Spindles: Conflicting Information

[mtnbikerxt]

Hi All,
New to the forums and to these trucks. Picked up a '70 C10 SWB last fall. Has a 350/350 combo with a leaf spring rear. Been lurking on the forum since I bought the truck. A great deal of information here!

The day I bought it.






Done a bit of work to it over the winter. Cleaned up the engine bay, all new brake hoses, rebuilt the drum brakes, new transmission pan gasket and filter, 3-point seatbelts, cleaned up the gauge cluster, new exhaust, new wheels and tires, etc...

What it looks like right now.







Anyways, I've decided to convert to disc brakes to make it a little safer to drive around town. The wheels are 6-bolt slot mags with 3.25" backspace with drum brakes on all four corners. Being that I like the location of the wheels in the wheel wells now, I had pretty much decided on the CPP OE Drop Spindle Kit with 6-lug rotors PN: 6370SWBK-6OE. They advertise that this only changes the front track width by 1/16" from the drum setup which is fine by me.

Here's the issue. From reading on the forum I know that these are a relatively new design (within the past few years). I contacted their customer support to confirm that the track width would not be changed significantly from the drum setup and here is the reply I got...

6370SWBK-6OE “This drops you 2.5 inches and moves your tires out ¾ an inch each side”

6370SWBK6OES “Stock height, same ¾ inch”

6370SWBK-6 “This is the one you want I think. Drops you 2 inches and Moves your tire in ¼ inch, so just a hair less then stock width” 799.00 This kit does not come stock height,

I went back and forth with their customer support over email but they could not explain the discrepancy between their own catalog, wheel offset chart (http://www.classicperform.com/Instru...fset_Chart.pdf) and what they wrote in the email.

Here's my question: Has anyone ordered this kit (6370SWBK-6OE) and determined what the track width change was from drums? Is the customer service rep just not up-to-date on the products? Any vendors on here that could confirm I would receive the new "smooth" casting spindles? I'm not keen on spending the extra for the "modular" spindles since I'll be staying with stock-size brakes. Thanks for all your help!

-Gen

[lolife99]

I've been on this board for a long time.
I'm still waiting for this info also.
CPP claims to narrow the track width.
By how much or compared to what,... I don't know.

[rob32472]

I bought a complete CPP suspension kit with there modular spindles and my track width changed by about 5/8 of an inch over my stock 71 width

[lolife99]

Originally Posted by rob32472

I bought a complete CPP suspension kit with there modular spindles and my track width changed by about 5/8 of an inch over my stock 71 width

5/8" total?
Or 5/8" per side?

[rob32472]

per side

[ksbrktracer]

Originally Posted by rob32472

I bought a complete CPP suspension kit with there modular spindles and my track width changed by about 5/8 of an inch over my stock 71 width

This is what we experienced too . Modulars "do narrow track width" compared to stock disc or drop spindles. We did this conversion from standard CPP Drop spindles to Modulars , gained about 1''-1-1/8' per side .


6370SWBK-6OE “This drops you 2.5 inches and moves your tires out ¾ an inch each side” .
This is correct as well, to my knowledge all disc spindles (other than CPP modulars) will widen the track width of a "drum brake truck" to the width of a 71-72.

And Yes I sell CPP.

[lolife99]

Originally Posted by ksbrktracer

This is what we experienced too . Modulars do narrow track width compared to stock disc or drop spindles.

Here's my issue:

1) Drum brake fronts have the narrowest oem track width.
2) stock oem 71-87 disc brake spindles are suppose to be 3/4" wider than oem drum brake spindles.
3) old school drop spindles are suppose to be 1/2"-3/4" wider than stock disc brake spindles.
(for tie rod and lower a-arm clearance, due to raising the spindle centerline)

Where do the CPP modular spindles track width fall in?

Ok,... suppose they are 5/8" narrower (per side) than stock disc brake spindles.
That makes them 1/4" WIDER (per side) than drum brake spindles.
Correct?

But yet CPP still just claims they move the wheels in.
If I had all the different spindles,... I would make a jig to put this issue to rest.
Seems like CPP could do this,... but they don't.

[67_C-30]

Originally Posted by lolife99

Here's my issue:

1) Drum brake fronts have the narrowed oem track width.
2) stock oem 71-87 disc brake spindles are suppose to be 3/4" wider than oem drum brake spindles.
3) old school drop spindles are suppose to be 1/2"-3/4" wider than stock disc brake spindles.
(for tie rod and lower a-arm clearance, due to raising the spindle centerline)

Where do the CPP modular spindles track width fall in?

Ok,... suppose they are 5/8" narrower (per side) than stock disc brake spindles.
That makes them 1/4" WIDER (per side) than drum brake spindles.
Correct?

But yet CPP still just claims they move the wheels in.
If I had all the different spindles,... I would make a jig to put this issue to rest.
Seems like CPP could do this,... but they don't.

Do you know what brand set-up makes for the widest wheel track possible?

[ksbrktracer]

Before I ordered them we point blank asked ..... What are they going to do to the truck. They said about 3/4" narrower than stock disc and about a 1/4" narrower than stock drum. He did go onto say that ride height , alignment etc can effect actual measurements as well .... which I agree with.

All of that being said ..... The truck was almost undrivable with the standard CPP drop disc spindle on a 67 and a 20X8.5 wheel with 4.50'' backspacing. Switching over to the CPP Modular spindles did pull the wheel in what looks like right at 1''-1-1/8'' of an inch . And the truck became drivable changing absolutely nothing but the spindles.

[mtnbikerxt]

Originally Posted by lolife99

Here's my issue:

1) Drum brake fronts have the narrowest oem track width.
2) stock oem 71-87 disc brake spindles are suppose to be 3/4" wider than oem drum brake spindles.
3) old school drop spindles are suppose to be 1/2"-3/4" wider than stock disc brake spindles.
(for tie rod and lower a-arm clearance, due to raising the spindle centerline)

Where do the CPP modular spindles track width fall in?

Ok,... suppose they are 5/8" narrower (per side) than stock disc brake spindles.
That makes them 1/4" WIDER (per side) than drum brake spindles.
Correct?

But yet CPP still just claims they move the wheels in.
If I had all the different spindles,... I would make a jig to put this issue to rest.
Seems like CPP could do this,... but they don't.

I believe I read somewhere that CPP uses the same casting for all of their drop spindles and simply drills for the different balljoint and tierod tapers. If this is the case, CPPs wheel offset chart suggests that there is a 0.5" difference in width between the stock '67-'70 drum and the '71-'87 disc spindles.

They say that their CP4SX spindles are 1/16" wider than drums, 7/16" narrower than stock discs.

They also say their CP30106 (modular) spindles are 1/4" narrower than drums, 3/4" narrower than stock discs.

Both suggest a 0.5" difference in width between the stock drum and stock disc spindles.

Originally Posted by big d's red67

This my truck Tommy is refering to, my track width from the out side of the tire to outside of the tire was 77 inches, after the install of the CPP modular spindles it was 74 9/16th inches from outside to outside of the tires.

Originally Posted by big d's red67

That measurement was going from a 2 1/2inch aftermarket drop spindle to the CPP modular. Also want to add the CPP modular is listed as a 2inch drop it more like 2 1/4 inch.

Originally Posted by lolife99

That figures up to 1.22" per side narrower.

If the old-school drop spindles moved the wheels out 1/2" per side relative to a stock disc spindle, moving from those to a modular spindle would move the wheels in 1-1/4" each side. Pretty much exactly what BigD experienced.

[mtnbikerxt]

Rob, I'm assuming they brought the wheels in relative to the stock '71 locations? If so, that fits well with the wheel offset chart on CPP's website which shows that the modular spindles should move the wheels in 3/4" per side relative to the stock '71 disc setup. Thanks for the input.

[rob32472]

That is correct the wheels moved in relative to the stock location

[mtnbikerxt]

Keith,
The wheel offset chart linked above seems to be clear. For 63-70 C10's they list the change "from drum" and for 71-72 C10's they list the change 'from disc'. Rob's experience above suggests that the numbers listed for the modular spindles, at least, are close to reality. The issue, of course, is that their customer service rep does not agree with the chart for either model of spindle.

Any chance someone has bought the smooth cast 'OE' spindles with built-in caliper mounting ears (PN: CP4SX) and has measured before and after?

[sduckworth13]

Good info here thank you guys for posting it. Sticky thread

[Stevo427]

I went from 6-lug drum to 6-lug modular cpp disc. I highly recommend going with the modular setup if you plan on dropping it. I run a 10" Wheel with a 255 tire up front and I have no real issues except wheel weights hit my control arms when turning. If I would of went with stock drop spindle setup my tire would be sticking out my fenders.

[Stevo427]

Here's how my tires sit. This is Modular Drop Spindles, 3-Inch Drop Coils, and a sway bar. I'm fairly sure without a sway bar my truck would sit a little lower in front. 10" Corvette Rally Wheel, 255/60/15

[sduckworth13]

That's a awesome looking truck Big D! Just checked out your build thread.

[67ctener]

All I can say is I'm running 2.5" modular spindles combined with bags on my truck with a 20x8 and 4.25 backspace. That seems to be hanging that front wheel out there and I don't know if it'd be possible with standard spindles.

[mtnbikerxt]

John, I have seen that document and it is linked above. I was about ready to order but decided to talk to CPP beforehand due to the lack of clarity in their documentation (catalog, website, etc.) Unfortunately, the customer service rep I spoke with did not provide the same information as found on the sheet you provided. This has caused a great deal of confusion on what exactly these spindles do to the track width of these trucks.

Can I ask where you got the sheet you have? I haven't seen it layed out like that before with dimensions 'from drum' and 'from disc' listed for all part numbers. Thanks!

[JOHNORO]

Originally Posted by mtnbikerxt

John, I have seen that document and it is linked above. I was about ready to order but decided to talk to CPP beforehand due to the lack of clarity in their documentation (catalog, website, etc.) Unfortunately, the customer service rep I spoke with did not provide the same information as found on the sheet you provided. This has caused a great deal of confusion on what exactly these spindles do to the track width of these trucks.

Can I ask where you got the sheet you have? I haven't seen it layed out like that before with dimensions 'from drum' and 'from disc' listed for all part numbers. Thanks!

I got the spec sheet while I was at Cpp yesterday. ..
They told me that this info is in the back of th new catalog as well as online, but they printed that particular sheet while there asking for clarification.
Javier or Jeff are the guys I ask for whenever I need anything answered..

[lolife99]

The confusion still exists.
Nothing in that chart matches up with this statement about 1-1/8".
(that would be 9/16" per side or 1-1/8" per side)


QUOTE:
Looking for a spindle and brake kit for your lowered truck with big tires and wheels? CPP's introduces their new modular 2" drop spindle and drop spindle wheel kits for 1960-87 Chevy pickups. This exclusive new “Simple Offset Solution” or SOS™ design helps solve tire to fender interference commonly found with lowered trucks. This new SOS™ technology was designed to address concerns about using aftermarket big wheels and tires by using different spindle/rotor offsets. Classic Performance’s new modular spindle and bracket works with factory 1971-87 C10 brake components, or for a HIGH performance option, combine CPP’s spindle with their new Big Brake 13" Rotor, Twin 52mm Piston Brake Caliper kit.
Classic Performance’s new Modular Spindle offers many benefits available for the first time, installs easy without modifications, works with factory ball joints and tie rod ends, lowers your truck a full 2", offers adjustable steering stops, provides 1-1/8" more fender to tire clearance, allows use with standard factory brakes and performance aftermarket "BIG" Brake Kits

[big d's red67]

[QUOTE=lolife99;6607765]The confusion still exists.
Nothing in that chart matches up with this statement about 1-1/8".
(that would be 5/8" per side or 1-1/8" per side)


We know for sure they will narrow the track width a little over an inch per side if you go from regular aftermarket drop spindles to the modular drop spindles.

[lolife99]

Then only this that can be assumed,... is that the CPP Modular spindles provide the "narrowest" track width.
We just don't know how much.

So don't buy your wheels or a-arm using any numbers other than what you have on your own tape measure, (in front of you),... after you have installed your spindles.
Whichever brand you choose to buy.

[sduckworth13]

Thanks Tommy for the info.

[sduckworth13]

Tommy, looks like a 20x8.5 with 4.5 in backspace on the front is the perfect choice if using the CPP modular drop spindle. What is the backspace on the rear wheels?