Drum to Disc, Changed Track Width

[1970 CST Short Wide]

So Eons ago when I changed from Stock Drums to Disc Brakes on the front of my 70 I recall it widening my track width. It was at least 30 years ago I used ECE 2 1/2 drop spindles to change over to disc.

On to present day; I just put a set of 20’s on with 245/45 on the front for more side wall. I had to bring the front up 1/4 “ (easy to do with coil overs) so not to rub the outside of the tire.

Now I see CPP makes a spindle that’s supposed to bring the track width back to the original drum brake spec or some where near depending on who you talk to. I even got two different answers from CPP, LOL. Anyway I have a set of theses spindles that I’m going to install as soon as I get the caliper brackets. This should give me all the tire clearance I need. I’ll keep you posted as I go along in the next couple weeks
If anybody else has already done this Please let me know how it turned out for you. Apparently it’s different for different years and now that I have all QA1 Control arms who knows ???????? Going to give it a shot

[tallic68]

Would love to hear you results patiently waiting your thoughts.

[lolife99]

Besides the spindle a LOT of the track width changes with the angle of the the lower control arms.
The flatter they are, the wider the track width.
So a shorter coil spring will also widen the track width because the lower control arm swings up in an arc.

[1970 CST Short Wide]

Originally Posted by lolife99

Besides the spindle a LOT of the track width changes with the angle of the the lower control arms.
The flatter they are, the wider the track width.
So a shorter coil spring will also widen the track width because the lower control arm swings up in an arc.

Ya, I’ve been trying to get my head around this. Now I don’t have a coil spring in the traditional since, I have coil over shocks. I’ll only be into this $325 and if it works it will be well worth it. If not, live and learn

[lolife99]

Many people have spent a ton of money trying to make wheels fit.
When in reality, you should install the suspension you want and buy wheels that fit.
Just my opinion.
Too many wheel companies are building the wrong offset wheels for their “off the shelf” affordable wheels.
Finally companies like Billet Specials and StreetMachinery have come up with the Speedway and Magneto wheels, with usable backspace numbers,… in a low price alternative to billet wheels.

[SCOTI]

Originally Posted by 1970 CST Short Wide

So Eons ago when I changed from Stock Drums to Disc Brakes on the front of my 70 I recall it widening my track width. It was at least 30 years ago I used ECE 2 1/2 drop spindles to change over to disc.

On to present day; I just put a set of 20’s on with 245/45 on the front for more side wall. I had to bring the front up 1/4 “ (easy to do with coil overs) so not to rub the outside of the tire.

Now I see CPP makes a spindle that’s supposed to bring the track width back to the original drum brake spec or some where near depending on who you talk to. I even got two different answers from CPP, LOL. Anyway I have a set of theses spindles that I’m going to install as soon as I get the caliper brackets. This should give me all the tire clearance I need. I’ll keep you posted as I go along in the next couple weeks
If anybody else has already done this Please let me know how it turned out for you. Apparently it’s different for different years and now that I have all QA1 Control arms who knows ???????? Going to give it a shot

Are you referring to their 'Modular' spindle?
Disc brake spindles = wider track width vs. drum brake spindles.

CPP makes a 'modular' drop spindle that is supposed to equal the drum brake spindle track width. The modular spindle requires the 'add-on' caliper bracket so you can select the appropriate bracket depending on what brake set-up you choose (stock caliper or aftermarket).

Standard disc brake spindles w/aftermarket brake hubs can increase track width depending on the hubs. So the modular spindle w/aftermarket big-brakes may possibly wind up the same track width wise as a standard disc set-up depending on the hub + rotor-hat combo (or only slightly narrower). I think one would have to verify w/the specific brake kit manufacture to know for sure what impact the brake set-up might have to track width.

[1970 CST Short Wide]

Originally Posted by SCOTI

Are you referring to their 'Modular' spindle?
Disc brake spindles = wider track width vs. drum brake spindles.

CPP makes a 'modular' drop spindle that is supposed to equal the drum brake spindle track width. The modular spindle requires the 'add-on' caliper bracket so you can select the appropriate bracket depending on what brake set-up you choose (stock caliper or aftermarket).

Standard disc brake spindles w/aftermarket brake hubs can increase track width depending on the hubs. So the modular spindle w/aftermarket big-brakes may possibly wind up the same track width wise as a standard disc set-up depending on the hub + rotor-hat combo (or only slightly narrower). I think one would have to verify w/the specific brake kit manufacture to know for sure what impact the brake set-up might have to track width.

Yes I have the New “Modular” spindles. A lot of what I’ve read along with talking to CPP tech (2 different answers on how much it should move )I’m hoping it works
I agree correct back spacing should be bought after the suspension is done. That ones my Bad , my math sucks.

[SCOTI]

Originally Posted by 1970 CST Short Wide

Yes I have the New “Modular” spindles. A lot of what I’ve read along with talking to CPP tech (2 different answers on how much it should move )I’m hoping it works
I agree correct back spacing should be bought after the suspension is done. That ones my Bad , my math sucks.

I just wanted to post that info because there are people out there that think even w/the modular spindles the track width won't change. It doesn't if using OE discs. Once you go aftermarket (bigger brakes) the hub & rotor dimensions can add to the width over what it is w/stock discs.

[1970 CST Short Wide]

Originally Posted by SCOTI

I just wanted to post that info because there are people out there that think even w/the modular spindles the track width won't change. I doesn't if using OE discs. Once you go aftermarket (bigger brakes) the hub & rotor dimensions can add to the width over what it is w/stock discs.

CPP told me it only works with 1 1/4 OE discs and that it will move in ~3/8 - 1/2 “. I’m willing to do the work and find out for sure we’ll see. Just waiting on the Brackets

[SCOTI]

Originally Posted by 1970 CST Short Wide

CPP told me it only works with 1 1/4 OE discs and that it will move in ~3/8 - 1/2 “. I’m willing to do the work and find out for sure we’ll see. Just waiting on the Brackets

Yep. They dont work w/the Lt.Duty truck brakes.

[1970 CST Short Wide]

Originally Posted by SCOTI

Yep. They dont work w/the Lt.Duty truck brakes.

Have you used theses spindles??

[SCOTI]

Originally Posted by 1970 CST Short Wide

Have you used theses spindles??

I have a pair on the front of my 64 project.

[1970 CST Short Wide]

Originally Posted by SCOTI

I have a pair on the front of my 64 project.

Cool, so did you go Big Brakes or OE. Any pics. I’d like to see how calipers bolt up

[SCOTI]

Originally Posted by 1970 CST Short Wide

Cool, so did you go Big Brakes or OE. Any pics

Currently has OE HD brakes & 15" steelies. I have a C6 Z51 brake set-up from KORE3 but can't use them w/o updating to >18" front wheels. Not quite ready for that expense until it's running/driving.

[1970 CST Short Wide]

Originally Posted by SCOTI

Currently has OE HD brakes & 15" steelies. I have a C6 Z51 brake set-up from KORE3 but can't use them w/o updating to >18" front wheels. Not quite ready for that expense until it's running/driving.

Got ya. Did you get the brackets from CPP also, and if so how well did they work

[SCOTI]

Originally Posted by 1970 CST Short Wide

Got ya. Did you get the brackets from CPP also, and if so how well did they work

The stock brake brackets came from CPP. The big brake brackets are from KORE3.

[1970 CST Short Wide]

Originally Posted by SCOTI

The stock brake brackets came from CPP. The big brake brackets are from KORE3.

I’m going to use all the OE stuff. Have you mounted the OE stuff or not. If so how did they look

[SCOTI]

Originally Posted by 1970 CST Short Wide

I’m going to use all the OE stuff. Have you mounted the OE stuff or not. If so how did they look

Yes. Removed the OE HD brakes from the stock spindles & they mounted up to the adapter brackets fine. They look like any other drop spindle once everything is assembled.

I also swapped to narrowed arms, did an air-bag to coil-overs swap, & modular sway bar @ the time so there were several changes going on.

[1970 CST Short Wide]

Parts should be here next week. Called for ETA and they said would ship by Monday
Then we’ll put this ? To rest. Stay tuned

[1970 CST Short Wide]

Ok so here is the answer. I put CPP module spindles on which moved my wheels IN ~ 1 inch
From where my old ECE spindles were.I measured both from Frame to top of rotor. The only thing I don’t like is there is no mount for dust shield
Both sets are 2 1/2 drop. Now I can reset ride height and have it aligned

[lolife99]

I thought the Modular spindle from CPP were only a 2” drop?
Thanks for the measurement and info.

[1970 CST Short Wide]

Originally Posted by lolife99

I thought the Modular spindle from CPP were only a 2” drop?
Thanks for the measurement and info.

You know I think your right. I rechecked before and after height and ya I’m setting a bit higher so I’m IN and UP. The Up I can adjust the IN helps

[SCOTI]

http://www.cpptalk.com/ShopTalkSite/st52.html

[lolife99]

Originally Posted by SCOTI

http://www.cpptalk.com/ShopTalkSite/st52.html

So now it’s a 2-1/2” drop spindle?
I can’t keep up.

[67ChevyRedneck]

Originally Posted by 1970 CST Short Wide

Ok so here is the answer. I put CPP module spindles on which moved my wheels IN ~ 1 inch
From where my old ECE spindles were.I measured both from Frame to top of rotor. The only thing I don’t like is there is no mount for dust shield
Both sets are 2 1/2 drop. Now I can reset ride height and have it aligned

It might have been more than that, if you're going by your 15" and 16" measurements to the rotors face... Wheels don't mount to the rotor face, it looks like the mounting flange is further back too. It looks more like you went from 16-7/8" to 15-5/8, maybe 3/4, hard to tell with angle. So maybe 1-1/8 to 1/1/4 per side? That's a big gain! I had to buy a set of 7" wheels for the front of my truck because my old 8" wheels rubbed bad with the drop.

I agree with the "off the shelf fits all" comment. I have a 68 firebird and bought a set of the 17" pontiac rally II wheels. Look killer. However, they really need to be sucked in 1/2" in the rear (fixable with rolling/cutting the fender lip) but the front really needs to go in 3/4-1" per side if you want to drop the nose of the car any at all. They're "work" with stock height springs, but barely and you have to run a small tire. These are claimed to "fit" all 1st and 2nd gens. They definitely fit the 69s and 2nd gens better (they're a couple inches wider). It's a shame because they look so great, but really, the offset is all wrong to fit 67/68s.