Do Disc Conversions Change Wheel Offset? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Injected68LS1 · 11-21-2003, 12:25 AM

So here is what I am trying to figure out.

I'm converting to a 5 lug disc brake setup from a 6 lug drum brake setup. To use the brakes, I need to have my new 5 lug wheels. So I don't want to order expensive wheels and find that the disc spindle has a changed offset. Any insight?

Thanks in advance.

Tx Firefighter · 11-21-2003, 12:48 AM

Drop spindles widen the track by about a 1/2 inch PER SIDE.

If you run drop spindles and exact same size tires front and rear, it will be plainly obvious.

Non-drop spindles, I do not know.

Injected68LS1 · 11-21-2003, 03:45 AM

Well, the new brakes will be on drop spindles.

So it should be safe to assume that I need to order wheels with 1/2 more backspacing than my current wheels?

Injected68LS1 · 11-21-2003, 03:47 AM

But what about the difference from drum brake to disc brake????

TEXAS 68 · 11-21-2003, 07:10 AM

I,m trying to find out also, I swapped to dics from an 85 and bought 6 lug rotors. I have a set of 16x8 with 5'' offset and need to know if it will work.

SCOTI · 11-21-2003, 08:41 AM

I looked this up years ago when I did my 67 (back around 1988/89) & the difference in track width was like 1" (1/2" per side) when swapping from drums to disc. This difference was related to the disc brake spindle & hub, so I found drop spindles don't widen the track width any more than stock disc spindles.

16x8 w/5" offset would work fine. I've used my 18x8 w/5.25" offset on my 68 & 74 trucks w/o issue. You will need to trim the lip of the lower control arm slightly for lock-to-lock steering clearance.

Injected68LS1 · 11-22-2003, 04:28 AM

Called ECE today. They said that the drop spindles and disc brakes move the track out 1-3/8" PER side. I never thought it would be that much. Hopefully that will hold true when I get everything assembled.

11-21-2003, 12:25 AM	#1
Injected68LS1 Registered User Join Date: Jul 2003 Location: So. Cal. Posts: 389	Do Disc Conversions Change Wheel Offset? So here is what I am trying to figure out. I'm converting to a 5 lug disc brake setup from a 6 lug drum brake setup. To use the brakes, I need to have my new 5 lug wheels. So I don't want to order expensive wheels and find that the disc spindle has a changed offset. Any insight? Thanks in advance. __________________ 1968 Chev SWB with 1998 Corvette LS1 305hp and 320 ftlb to the wheels (stock engine!) AEM EMS and wideband O2 sensors Bowtie Overdrive's 700R4, stage 3 Baer 4 wheel discs and 20s http://iciclelanding.com/aperture?album=2049&view=album

11-21-2003, 12:48 AM	#2
Tx Firefighter Watch out for your cornhole ! Join Date: Jun 2003 Location: Azle, Texas Posts: 14,162	Drop spindles widen the track by about a 1/2 inch PER SIDE. If you run drop spindles and exact same size tires front and rear, it will be plainly obvious. Non-drop spindles, I do not know. __________________ I'm on the Instagram- @Gearhead_Kevin

11-21-2003, 03:45 AM	#3
Injected68LS1 Registered User Join Date: Jul 2003 Location: So. Cal. Posts: 389	Well, the new brakes will be on drop spindles. So it should be safe to assume that I need to order wheels with 1/2 more backspacing than my current wheels? __________________ 1968 Chev SWB with 1998 Corvette LS1 305hp and 320 ftlb to the wheels (stock engine!) AEM EMS and wideband O2 sensors Bowtie Overdrive's 700R4, stage 3 Baer 4 wheel discs and 20s http://iciclelanding.com/aperture?album=2049&view=album

11-21-2003, 03:47 AM	#4
Injected68LS1 Registered User Join Date: Jul 2003 Location: So. Cal. Posts: 389	But what about the difference from drum brake to disc brake???? __________________ 1968 Chev SWB with 1998 Corvette LS1 305hp and 320 ftlb to the wheels (stock engine!) AEM EMS and wideband O2 sensors Bowtie Overdrive's 700R4, stage 3 Baer 4 wheel discs and 20s http://iciclelanding.com/aperture?album=2049&view=album

11-21-2003, 07:10 AM	#5
TEXAS 68 Vortec in the works Join Date: Nov 2003 Location: Spring,Texas Posts: 735	I,m trying to find out also, I swapped to dics from an 85 and bought 6 lug rotors. I have a set of 16x8 with 5'' offset and need to know if it will work. __________________ 68? It's all figured out untill you get it apart. Is it Sunday yet??? 68 Project 68 SWB frame off/98 Vortec with stock FI/power everything. 95 ECLB 2500 with 346,000 on the clock(the original HD) 99 Lesabre-wifes ride 08 Crew Cab LTZ-All Mine 89 SWB 5/7 drop-Son's first ride.

11-21-2003, 08:41 AM	#6
SCOTI Registered User Join Date: Apr 2001 Location: DALLAS,TX Posts: 22,080	I looked this up years ago when I did my 67 (back around 1988/89) & the difference in track width was like 1" (1/2" per side) when swapping from drums to disc. This difference was related to the disc brake spindle & hub, so I found drop spindles don't widen the track width any more than stock disc spindles. 16x8 w/5" offset would work fine. I've used my 18x8 w/5.25" offset on my 68 & 74 trucks w/o issue. You will need to trim the lip of the lower control arm slightly for lock-to-lock steering clearance. __________________ 67SWB-B.B.RetroRod 64SWB-Recycle 89CCDually-Driver/Tow Truck 99CCSWB Driver All Fleetsides @rattlecankustoms in IG Building a small, high rpm engine with the perfect bore, stroke and rod ratio is very impressive. It's like a highly skilled Morrocan sword fighter with a Damascus Steel Scimitar..... *Cubic inches is like Indiana Jones with a cheap pistol.*

11-22-2003, 04:28 AM	#7
Injected68LS1 Registered User Join Date: Jul 2003 Location: So. Cal. Posts: 389	Called ECE today. They said that the drop spindles and disc brakes move the track out 1-3/8" PER side. I never thought it would be that much. Hopefully that will hold true when I get everything assembled. __________________ 1968 Chev SWB with 1998 Corvette LS1 305hp and 320 ftlb to the wheels (stock engine!) AEM EMS and wideband O2 sensors Bowtie Overdrive's 700R4, stage 3 Baer 4 wheel discs and 20s http://iciclelanding.com/aperture?album=2049&view=album

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