Low Buck 6 lug rotors - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Harold Shepard · 05-28-2005, 09:49 PM

I had been looking for a cheap alternative to 6 lug rotors, so I would not have to switch wheels or rear axles, so after talking to member firstgen I figured what the hay and went for it. I got rotors for a 1990 3/4 light duty (7200 gvw) 2wd truck. The rotors use the same inner and outer wheel bearings as 71-up as well as the same seal. These are a direct bolt in as long as you have 71-up spindles, only one modification needed to be made, the rotors use a metric lug nut - $15 for twelve and the best part depending on where you get the rotors the price ranges from $43- $60 bucks- this beats $84 or more from other sources. Thought that some of you would appreciate this bit of info. Harold

**lolife99** · 05-28-2005, 09:54 PM

Great TIP! How about some pics when you get time. Thanks,... lolife99.

MOTHERTRUCKERS · 05-29-2005, 07:24 AM

What calipers do you use?

Harold Shepard · 05-29-2005, 11:03 AM

Ed I am using 71- up calipers, the rotor is the same thickness as the rotors offered originally and as the 6 lug replacement- 1 1/4"- other than the difference in lug studs (1.5 pitch 14mm), I can't find any differences from 5 lug originals or the 6 lug replacements offered currently. The rotors are the same size and consume the same amount of space in the 80's model 4x4 rallies. I feel like I am going to have problems with the stock hard lines and the hoses coupled with the 69-70 crossmember. I got a great deal on new 69-70 hard lines but do not know what to do about the prop valve- other than bend new lines from the prop valve to the M/C and then adapt the hard lines to the prop valve.... Any ideas? Harold

**passthebuck** · 05-29-2005, 04:21 PM

Oh man this is a sweet thread! I just love ez conversions that are almost bolt-ons!

LUV2XCLR8 · 05-29-2005, 04:38 PM

Quote:

Originally Posted by passthebuck

Oh man this is a sweet thread! I just love ez conversions that are almost bolt-ons!

purple gas · 05-29-2005, 08:36 PM

I'm wondering about how much fluid it takes to push the calipers as compared to the cylinders in the drum type? will your master cylinder work?

FirstGen · 05-29-2005, 08:47 PM

Quote:

Originally Posted by Harold Shepard

I had been looking for a cheap alternative to 6 lug rotors, so I would not have to switch wheels or rear axles, so after talking to member firstgen I figured what the hay and went for it. I got rotors for a 1990 3/4 light duty (7200 gvw) 2wd truck. The rotors use the same inner and outer wheel bearings as 71-up as well as the same seal. These are a direct bolt in as long as you have 71-up spindles, only one modification needed to be made, the rotors use a metric lug nut - $15 for twelve and the best part depending on where you get the rotors the price ranges from $43- $60 bucks- this beats $84 or more from other sources. Thought that some of you would appreciate this bit of info. Harold

The best part about it is that you can swap to 5 lug anytime with just a quick trip to AutoZone...

**passthebuck** · 05-29-2005, 10:06 PM

purple gas: I know that master cylinders do not interchange, but I'm not sure excatly why, BUT I think it's either more pressure and/or volume on the disc side....

GloryHound · 05-29-2005, 10:18 PM

Actually from that I've heard is it takes less pressure on disc brakes than drum. Also if you should be able to fit a later model booster and master cylinder on our trucks just be using the old rod and brackets. As for Hard lines should be close from a later model truck also, I would try getting an old set from a junk yard for a couple of bucks and testing fit then order new ones for that year of truck. Just some thoughts and feel free to correct me if I'm wrong!

**VetteVet** · 05-29-2005, 11:14 PM

The calipers need more fluid volume ( bigger cylinder ) and the prop valve should be adjustable. the best thing is to swap master cylinders with the donor truck. Some of the board members say they have had no problems with the stock ones though.

68w/sbc406 · 05-30-2005, 01:02 AM

the disc/drum masters hold more fluid that the drum/drum ones. i was getting all my parts together to do my front disc swap when my master cylinder went out. i bolted a disc/drum one on and it feels just like it did before it went out

**VetteVet** · 05-30-2005, 01:23 AM

Quote:

Originally Posted by 68w/sbc406

the disc/drum masters hold more fluid that the drum/drum ones. i was getting all my parts together to do my front disc swap when my master cylinder went out. i bolted a disc/drum one on and it feels just like it did before it went out

Are you saying that you bolted a disc/drum MC on before you swapped to discs and it felt the same? If so that would be correct because the drums require less fluid than the discs and the d/d MC provides more than enough whereas the drum MC may not be able to actuate the calipers without running low on brake fluid or pedal low to the floor.

68w/sbc406 · 05-30-2005, 01:37 AM

thats exacty what i am saying. just verifing that there is no pressure change between disc/drum and drum/drum masters. only a difference in volume of fluid

FirstGen · 05-30-2005, 11:28 AM

Yeah, I second that. I bolted on a disc/drum master when I still had 4 wheel drums and it felt the same. By the way our 4 wheel drum trucks have no factory prop valve. You will probably want to get a universal inline valve like a wilwood or similar. They are only like 40 bucks. Otherwise, the back will lock up pretty easy.

05-28-2005, 09:49 PM	#1
Harold Shepard Registered User Join Date: May 2004 Location: Canton North Carolina Posts: 466	Low Buck 6 lug rotors I had been looking for a cheap alternative to 6 lug rotors, so I would not have to switch wheels or rear axles, so after talking to member firstgen I figured what the hay and went for it. I got rotors for a 1990 3/4 light duty (7200 gvw) 2wd truck. The rotors use the same inner and outer wheel bearings as 71-up as well as the same seal. These are a direct bolt in as long as you have 71-up spindles, only one modification needed to be made, the rotors use a metric lug nut - $15 for twelve and the best part depending on where you get the rotors the price ranges from $43- $60 bucks- this beats $84 or more from other sources. Thought that some of you would appreciate this bit of info. Harold

05-28-2005, 09:54 PM	#2
lolife99 67-72 parts collector,… Join Date: Nov 2002 Location: Mid-MO Posts: 22,704	Great TIP! How about some pics when you get time. Thanks,... lolife99. __________________ Keith Convert to disc brakes. http://67-72chevytrucks.com/vboard/s...d.php?t=444823

05-29-2005, 07:24 AM	#3
MOTHERTRUCKERS Registered User Join Date: Dec 1999 Location: BRADENTON FLA Posts: 3,269	What calipers do you use? __________________ Rest in Peace Ed. Thanks for all the good times.

05-29-2005, 11:03 AM	#4
Harold Shepard Registered User Join Date: May 2004 Location: Canton North Carolina Posts: 466	Ed I am using 71- up calipers, the rotor is the same thickness as the rotors offered originally and as the 6 lug replacement- 1 1/4"- other than the difference in lug studs (1.5 pitch 14mm), I can't find any differences from 5 lug originals or the 6 lug replacements offered currently. The rotors are the same size and consume the same amount of space in the 80's model 4x4 rallies. I feel like I am going to have problems with the stock hard lines and the hoses coupled with the 69-70 crossmember. I got a great deal on new 69-70 hard lines but do not know what to do about the prop valve- other than bend new lines from the prop valve to the M/C and then adapt the hard lines to the prop valve.... Any ideas? Harold Last edited by Harold Shepard; 05-29-2005 at 11:04 AM.

05-29-2005, 04:21 PM	#5
passthebuck Sisyphus was my mentor! Join Date: Sep 2002 Location: Carleton Place, Ontario CANADA Posts: 984	Oh man this is a sweet thread! I just love ez conversions that are almost bolt-ons! __________________ passthebuck #5642 -TWO 1967 GMC 910's. One with L6/3-on-the tree and the other with 355 w/435hp & a 700r4. -a 2013 Honda Civic as my "sensible" car

05-29-2005, 08:36 PM	#7
purple gas Registered User Join Date: Oct 2004 Location: saskatoon, planet earth Posts: 697	I'm wondering about how much fluid it takes to push the calipers as compared to the cylinders in the drum type? will your master cylinder work? __________________ I got a bench seat baby, you don't have to sit over there.

05-29-2005, 10:06 PM	#9
passthebuck Sisyphus was my mentor! Join Date: Sep 2002 Location: Carleton Place, Ontario CANADA Posts: 984	purple gas: I know that master cylinders do not interchange, but I'm not sure excatly why, BUT I think it's either more pressure and/or volume on the disc side.... __________________ passthebuck #5642 -TWO 1967 GMC 910's. One with L6/3-on-the tree and the other with 355 w/435hp & a 700r4. -a 2013 Honda Civic as my "sensible" car

05-29-2005, 10:18 PM	#10
GloryHound Working on a Nova. Join Date: Nov 2002 Location: ## Posts: 506	Actually from that I've heard is it takes less pressure on disc brakes than drum. Also if you should be able to fit a later model booster and master cylinder on our trucks just be using the old rod and brackets. As for Hard lines should be close from a later model truck also, I would try getting an old set from a junk yard for a couple of bucks and testing fit then order new ones for that year of truck. Just some thoughts and feel free to correct me if I'm wrong!

05-29-2005, 11:14 PM	#11
VetteVet Msgt USAF Ret Join Date: Jan 2005 Location: Kalamazoo, Michigan Posts: 8,719	The calipers need more fluid volume ( bigger cylinder ) and the prop valve should be adjustable. the best thing is to swap master cylinders with the donor truck. Some of the board members say they have had no problems with the stock ones though. __________________ VetteVet metallic green 67 stepside 74 corvette convertible 1965 Harley sportster 1995 Harley wide glide Growing old is hell, but it beats the alternative.

05-30-2005, 01:02 AM	#12
68w/sbc406 Got Light Emitting Diode? Join Date: Apr 2004 Location: Newberg, OR Posts: 2,485	the disc/drum masters hold more fluid that the drum/drum ones. i was getting all my parts together to do my front disc swap when my master cylinder went out. i bolted a disc/drum one on and it feels just like it did before it went out __________________ 1968 1/2 ton 2wd lwb 6 lug disc and bags up front. Next c notch and rear bags '02 Chevy Silverado LT ext cab short bed 2WD 5/7 drop on 22's(the family car) 1993 Cherokee work ride/weekend wheeler

05-30-2005, 01:37 AM	#14
68w/sbc406 Got Light Emitting Diode? Join Date: Apr 2004 Location: Newberg, OR Posts: 2,485	thats exacty what i am saying. just verifing that there is no pressure change between disc/drum and drum/drum masters. only a difference in volume of fluid __________________ 1968 1/2 ton 2wd lwb 6 lug disc and bags up front. Next c notch and rear bags '02 Chevy Silverado LT ext cab short bed 2WD 5/7 drop on 22's(the family car) 1993 Cherokee work ride/weekend wheeler

05-30-2005, 11:28 AM	#15
FirstGen Just Don't Stop! Join Date: Feb 2004 Location: Dallas Posts: 1,239	Yeah, I second that. I bolted on a disc/drum master when I still had 4 wheel drums and it felt the same. By the way our 4 wheel drum trucks have no factory prop valve. You will probably want to get a universal inline valve like a wilwood or similar. They are only like 40 bucks. Otherwise, the back will lock up pretty easy. __________________ 1968 C10 build in process TT LSA/6L90e/9"



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