Center bore for 6 lug? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

GreyHoundSteve · 12-28-2004, 11:06 AM

Does anyone know what the center bore of the 6 lug bolt patern for our truck is? The reason i ask is because i know the bolt patern is the same as the late model 6 lug trucks but i have heard that the hib is another size and im rim shopping and need to know thw hub size of the older 6 lug patern.

gr8scott51 · 12-28-2004, 01:03 PM

A lot of the newer rims won't work on our trucks because of the back spacing, also. Stock back space (distance from back side of the center hub to the inner bead) is 4-1/2". If the back spacing is much more than that, there will be rubbing on the frame, inner fender during turns. If you are still running drum brakes up front, you may have interference with your steering arm.

GreyHoundSteve · 12-28-2004, 02:07 PM

Quote:

Originally Posted by gr8scott51

A lot of the newer rims won't work on our trucks because of the back spacing, also. Stock back space (distance from back side of the center hub to the inner bead) is 4-1/2". If the back spacing is much more than that, there will be rubbing on the frame, inner fender during turns. If you are still running drum brakes up front, you may have interference with your steering arm.

I got a 6 lug disc up front and the rims are only 5 1/8 bs so i think im fine there but it might be a problem with the rear drums because its a wider rim with 5.6 bs.

Does anyone know the hub size of the old 6 lugs???

REPO1 · 12-28-2004, 07:33 PM

So would this be the measurment of the inside hole of the rear drum? Do you mean the flange on the axle that the drum and rim would slide over? If so I have a pair of 6 lug drums laying here I could measure the I.D. of the hole.

GreyHoundSteve · 12-28-2004, 07:36 PM

Quote:

Originally Posted by REPO1

So would this be the measurment of the inside hole of the rear drum? Do you mean the flange on the axle that the drum and rim would slide over? If so I have a pair of 6 lug drums laying here I could measure the I.D. of the hole.

That would be great Thanks. I dont really know what is meant by "hub" but i have heard from a couple people that the hub is larger on the old 6 bolt patern than on the newer trucks and i want to see how much the difference is.

REPO1 · 12-28-2004, 07:52 PM

Yes the hub on the 6 lug trucks is larger than the 5 lug. I just had my 6 lug axles redrilled to the 5 bolt pattern and had the have the center hub machined down so the new 1972 5 lug drums would slide on.

I'll go measure it for you right now. Be back in 5 mins.

Reid

REPO1 · 12-28-2004, 07:55 PM

OK the center hole of the 6 lug drum measures at a hair over 3.5" so I would think the hub on the axle is probobly exactly 3.5"

If you need it I can measure a new 5 lug axle drum as well.

Reid

*Randy70C-10* · 12-28-2004, 08:14 PM

Steve is correct, the later model six lug rims have a smaller center hole and won't fit on our trucks, I found this out "after" purchasing a complete set of rims.

FirstGen · 12-28-2004, 08:32 PM

You could always bore the wheel and get different center caps. A guy on the board did this to a nice set of Eagle wheels a while back. Not sure how it all turned out but the 20's looked GREAT obviously.

Iman · 12-28-2004, 09:11 PM

Greyhound, I am currently working on this same problem. I have just ordered 1/2'" spacer off of e-bay. And also ordered lug nuts to fit on 7/16" studs but convert to 14mm so I can use the black lug nut covers that hold the center cap on. I may have to use longer studs?? Otherwise we were going to turn the center of the wheels to 4". When I get the order I'll let you know how it turns out. I converting to 16" rims from a 2003 Chevy. Sounds like alot of good info form above replies, I'll have to check clearance for fender wells and etc... Iman

GreyHoundSteve · 12-29-2004, 10:30 AM

I have heard from a couple members that you can bore the center hub on the rim to fit and one member told me he machined the rotor to fir. I am going to pick my rims up on Friday and hope for the best. I think i am also going to have back spacing trouble because the rims i got for the rear measure 22X9.5 with 5.682 bsm. I will probably have to use a spacer on these so i would think that might cure the problem on the back rims. The fronts are 20X8.5 with 5 1/8 bsm so they should fit without too many problems providing that i can make the hub fit. Machining the rotors seems like a better option than machining the rims since the price of both rotos was less than 1 rim. Does anyone know if machining down the hib on the front rotors would be a problem?

GreyHoundSteve · 12-29-2004, 11:08 AM

I just looked at the "center bore" on the rims and it says its 108.20mm. Does anyone know what this means? Repo said the center hub on his 6 lug drums is about 3.5". Are we talking about the same thing here? By my math thats 4.26 inches so i guess that means i wont have to worry about machining anything..... if what i think this means is correct???

GreyHoundSteve · 12-29-2004, 11:11 AM

Heres a picture of what im talking about.

FirstGen · 12-29-2004, 11:22 AM

dont' see any pics Steve?

redz 1970 K5 · 12-29-2004, 11:28 AM

I got a set of wheels off of a 99 K1500... They fit. American Racing has 2 part numbers on certain lines- one part for ALL trucks and one part for hubcentric trucks (99 newer) If you want to remove all doubt, get the part number and call the vendor...

GreyHoundSteve · 12-29-2004, 11:50 AM

Quote:

Originally Posted by FirstGen

dont' see any pics Steve?

hmmm tried twice, for some reason it wont show up. Heres another try.

*Randy70C-10* · 12-29-2004, 12:39 PM

Yep, that would be correct Steve. You shouldn't have any problem with those.

Vince M · 12-29-2004, 12:52 PM

From the picture it lists the offset at 10mm. The numbers you listed for back space don't match the pic. If you take the rim width (8.5) and divide it by 2, the offset is from that dimension so your only 10mm from 4.25". Your backspace looks good. Going over 5" as you stated would mean spacers. I know..I'm more confused than ever now.

GreyHoundSteve · 12-29-2004, 02:22 PM

Quote:

Originally Posted by Vince M

From the picture it lists the offset at 10mm. The numbers you listed for back space don't match the pic. If you take the rim width (8.5) and divide it by 2, the offset is from that dimension so your only 10mm from 4.25". Your backspace looks good. Going over 5" as you stated would mean spacers. I know..I'm more confused than ever now.

The rear rims are 22X9.5 with 5.62 " bs and +14mm offset. Those are the ones im most concerned about fitting.

incoma · 12-29-2004, 08:37 PM

Just some more useless info - I've got the ECE disc kit on my 70. The hubs on those are 3" + a tiny bit.

Additionally 25.4 mm per inch. Those center holes on your 22's are about 4".

GreyHoundSteve - How do your front rims fit? I was under the impression from all of my reading that we can't use a rim over 4.5" of b/s on the front otherwise we'd rub the rim/tire on the inner fender and/or frame.

**lolife99** · 12-29-2004, 09:31 PM

incoma,... I have seen as much as 5.25 in the front (on an 18" rim.) My 17's on the blazer have a 5" backspace on the front.

incoma · 12-30-2004, 04:17 AM

And the 17's don't rub at all? Did you modify your inner fenders at all?

Tx Firefighter · 12-30-2004, 09:03 AM

Quote:

Originally Posted by incoma

And the 17's don't rub at all? Did you modify your inner fenders at all?

I've run 17x8 wheels with 5" B.S. under 4/6 lowered 72 truck with no rubbing anywhere. I have a picture if you want to see how they fit.

incoma · 12-30-2004, 09:44 AM

I image you're referring to your green stepside that you sold? I didn't realize you had 17"..

GreyHoundSteve · 12-30-2004, 10:13 AM

I heard from a few members that if you run larger than 16" rims youll be okay with 5"bs so i figure since im running 20's up front i should be okay with 5 1/8 but its just a guess at this point. I am going to go pick up the rims Friday and do a test fit on Saturday. I wont have any rubber on them but it should give me an idea on what needs to be done to make them fit. I will report back on my findings (with some new questions im sure).

12-28-2004, 11:06 AM	#1
GreyHoundSteve Registered User Join Date: Oct 2004 Location: DFW TX Posts: 769	Center bore for 6 lug? Does anyone know what the center bore of the 6 lug bolt patern for our truck is? The reason i ask is because i know the bolt patern is the same as the late model 6 lug trucks but i have heard that the hib is another size and im rim shopping and need to know thw hub size of the older 6 lug patern.

12-28-2004, 01:03 PM	#2
gr8scott51 Registered User Join Date: Mar 2003 Location: Bremerton, WA Posts: 1,839	A lot of the newer rims won't work on our trucks because of the back spacing, also. Stock back space (distance from back side of the center hub to the inner bead) is 4-1/2". If the back spacing is much more than that, there will be rubbing on the frame, inner fender during turns. If you are still running drum brakes up front, you may have interference with your steering arm. __________________ Silence is golden, duct tape is silver. - Scott

12-28-2004, 07:33 PM	#4
REPO1 Shortbox wanna-be. Join Date: Mar 2002 Location: Fort St.John, British Columbia, Canada Posts: 773	So would this be the measurment of the inside hole of the rear drum? Do you mean the flange on the axle that the drum and rim would slide over? If so I have a pair of 6 lug drums laying here I could measure the I.D. of the hole. __________________ 1970 Chevy C20 Custom Camper 402BB Turbo 400 trans. (Slowly becoming a '70 shortbox 1/2 ton) '71 Camaro SS 402/T400 resto '97 Z28 (11.41@127MPH)

12-28-2004, 07:52 PM	#6
REPO1 Shortbox wanna-be. Join Date: Mar 2002 Location: Fort St.John, British Columbia, Canada Posts: 773	Yes the hub on the 6 lug trucks is larger than the 5 lug. I just had my 6 lug axles redrilled to the 5 bolt pattern and had the have the center hub machined down so the new 1972 5 lug drums would slide on. I'll go measure it for you right now. Be back in 5 mins. Reid __________________ 1970 Chevy C20 Custom Camper 402BB Turbo 400 trans. (Slowly becoming a '70 shortbox 1/2 ton) '71 Camaro SS 402/T400 resto '97 Z28 (11.41@127MPH)

12-28-2004, 07:55 PM	#7
REPO1 Shortbox wanna-be. Join Date: Mar 2002 Location: Fort St.John, British Columbia, Canada Posts: 773	OK the center hole of the 6 lug drum measures at a hair over 3.5" so I would think the hub on the axle is probobly exactly 3.5" If you need it I can measure a new 5 lug axle drum as well. Reid __________________ 1970 Chevy C20 Custom Camper 402BB Turbo 400 trans. (Slowly becoming a '70 shortbox 1/2 ton) '71 Camaro SS 402/T400 resto '97 Z28 (11.41@127MPH)

12-28-2004, 08:14 PM	#8
Randy70C-10 Account Suspended Join Date: Mar 2001 Location: Virginia Beach, Va. U.S.A. Posts: 15,320	Steve is correct, the later model six lug rims have a smaller center hole and won't fit on our trucks, I found this out "after" purchasing a complete set of rims.

12-28-2004, 08:32 PM	#9
FirstGen Just Don't Stop! Join Date: Feb 2004 Location: Dallas Posts: 1,239	You could always bore the wheel and get different center caps. A guy on the board did this to a nice set of Eagle wheels a while back. Not sure how it all turned out but the 20's looked GREAT obviously. __________________ 1968 C10 build in process TT LSA/6L90e/9"

12-28-2004, 09:11 PM	#10
Iman Registered User Join Date: Nov 2004 Posts: 3	Greyhound, I am currently working on this same problem. I have just ordered 1/2'" spacer off of e-bay. And also ordered lug nuts to fit on 7/16" studs but convert to 14mm so I can use the black lug nut covers that hold the center cap on. I may have to use longer studs?? Otherwise we were going to turn the center of the wheels to 4". When I get the order I'll let you know how it turns out. I converting to 16" rims from a 2003 Chevy. Sounds like alot of good info form above replies, I'll have to check clearance for fender wells and etc... Iman

12-29-2004, 10:30 AM	#11
GreyHoundSteve Registered User Join Date: Oct 2004 Location: DFW TX Posts: 769	I have heard from a couple members that you can bore the center hub on the rim to fit and one member told me he machined the rotor to fir. I am going to pick my rims up on Friday and hope for the best. I think i am also going to have back spacing trouble because the rims i got for the rear measure 22X9.5 with 5.682 bsm. I will probably have to use a spacer on these so i would think that might cure the problem on the back rims. The fronts are 20X8.5 with 5 1/8 bsm so they should fit without too many problems providing that i can make the hub fit. Machining the rotors seems like a better option than machining the rims since the price of both rotos was less than 1 rim. Does anyone know if machining down the hib on the front rotors would be a problem?

12-29-2004, 11:08 AM	#12
GreyHoundSteve Registered User Join Date: Oct 2004 Location: DFW TX Posts: 769	I just looked at the "center bore" on the rims and it says its 108.20mm. Does anyone know what this means? Repo said the center hub on his 6 lug drums is about 3.5". Are we talking about the same thing here? By my math thats 4.26 inches so i guess that means i wont have to worry about machining anything..... if what i think this means is correct???

12-29-2004, 11:11 AM	#13
GreyHoundSteve Registered User Join Date: Oct 2004 Location: DFW TX Posts: 769	Heres a picture of what im talking about. Last edited by GreyHoundSteve; 12-29-2004 at 11:13 AM.

12-29-2004, 11:22 AM	#14
FirstGen Just Don't Stop! Join Date: Feb 2004 Location: Dallas Posts: 1,239	dont' see any pics Steve? __________________ 1968 C10 build in process TT LSA/6L90e/9"

12-29-2004, 11:28 AM	#15
redz 1970 K5 OBS guy Join Date: Jun 2004 Location: SoCal Posts: 1,060	I got a set of wheels off of a 99 K1500... They fit. American Racing has 2 part numbers on certain lines- one part for ALL trucks and one part for hubcentric trucks (99 newer) If you want to remove all doubt, get the part number and call the vendor... __________________ 88 Suburban Goodies- Alpine, Auto Meter, BDS, Bilstein, B&M, BFG, Borgeson, Bushwhacker, Cowl hood, Flowmaster, Genuine Gear, Holley, Infinity, JVC, K&N, MB Wheels, MSD, Pioneer, Skyjacker, Sony, Thorley, Walker + more

12-29-2004, 12:39 PM	#17
Randy70C-10 Account Suspended Join Date: Mar 2001 Location: Virginia Beach, Va. U.S.A. Posts: 15,320	Yep, that would be correct Steve. You shouldn't have any problem with those.

12-29-2004, 12:52 PM	#18
Vince M Senior Member Join Date: Apr 2000 Location: Orlando, FL Posts: 1,076	From the picture it lists the offset at 10mm. The numbers you listed for back space don't match the pic. If you take the rim width (8.5) and divide it by 2, the offset is from that dimension so your only 10mm from 4.25". Your backspace looks good. Going over 5" as you stated would mean spacers. I know..I'm more confused than ever now. __________________ ............................................................ 68 Chevy CST SWB w/LS1, carb & 700r4. Golden Anniversary clone with a few improvements.



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12-29-2004, 08:37 PM	#20
incoma Registered User Join Date: Mar 2004 Location: Lexington, KY Posts: 865	Just some more useless info - I've got the ECE disc kit on my 70. The hubs on those are 3" + a tiny bit. Additionally 25.4 mm per inch. Those center holes on your 22's are about 4". GreyHoundSteve - How do your front rims fit? I was under the impression from all of my reading that we can't use a rim over 4.5" of b/s on the front otherwise we'd rub the rim/tire on the inner fender and/or frame.

12-29-2004, 09:31 PM	#21
lolife99 67-72 parts collector,… Join Date: Nov 2002 Location: Mid-MO Posts: 22,692	incoma,... I have seen as much as 5.25 in the front (on an 18" rim.) My 17's on the blazer have a 5" backspace on the front. __________________ Keith Convert to disc brakes. http://67-72chevytrucks.com/vboard/s...d.php?t=444823

12-30-2004, 04:17 AM	#22
incoma Registered User Join Date: Mar 2004 Location: Lexington, KY Posts: 865	And the 17's don't rub at all? Did you modify your inner fenders at all?

12-30-2004, 09:44 AM	#24
incoma Registered User Join Date: Mar 2004 Location: Lexington, KY Posts: 865	I image you're referring to your green stepside that you sold? I didn't realize you had 17"..

12-30-2004, 10:13 AM	#25
GreyHoundSteve Registered User Join Date: Oct 2004 Location: DFW TX Posts: 769	I heard from a few members that if you run larger than 16" rims youll be okay with 5"bs so i figure since im running 20's up front i should be okay with 5 1/8 but its just a guess at this point. I am going to go pick up the rims Friday and do a test fit on Saturday. I wont have any rubber on them but it should give me an idea on what needs to be done to make them fit. I will report back on my findings (with some new questions im sure).

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