brake booster question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

rodstored-72 · 01-21-2020, 01:02 AM

ok guys.. I give up I have looked & looked & I am not able to find what the nut size (mainly the stud size) is for the brake booster bracket. I had to replace the(6) nuts that hold the booster (bracket) to the firewall?? this could be a trivia question for Keith Seymore I bet!!

thanks!!

blazer2007 · 01-21-2020, 11:06 AM

for some reason mine were metric ,1980 truck

**MikeB** · 01-21-2020, 01:15 PM

Do you have a way to measure the stud diameter? My truck doesn't have a booster, but I'd suspect your threads are either 3/8-24, 3/8-16 or, if metric 8mmx1.25 or 8mmx1.00.

I find thread gauges like these to be indispensable:

**mongocanfly** · 01-21-2020, 01:47 PM

Do you still have the nuts?...if so take them to fastenal or a bolt store
Thread gauges like Mike showed really come in handy..

rodstored-72 · 01-21-2020, 03:45 PM

mike,
thanks!! I "think" I have a friend that has a thread gauge. No I do not have the the original nuts, i believe they might have been "tossed out" on accident. I wanted to clean the studs up but don't know the size to get to run over them & then replace the nuts with new.... It was my bad during the teardown process- I meant to keep them though....aarrrggg
I tried looking in some e-manuals & such, but to know avail......

rodstored-72 · 01-26-2020, 04:53 PM

well, I dug through more boxes and finally found them. I do believe they are metric, but the nuts seem to “feel” good in my 3/8-16 threader. so, i chased them and then proceeded to install. i still would like to know the answer.... hoping this might be worthy of keith seymore to chime in... LOL
thanks, I will update my thread with pics too

Pontiac1976 · 02-02-2020, 02:59 PM

The nuts are crushed a little keep them from backing off (so the holes are not totally round) If you can't factory use plastic insert nut( locking nuts) If you have headers use lock washers nuts. Or there is type that has 4 small cuts at the top of the nut squeeze lock. I think 3/8 studs, yes thread gauges come in handy more then you think.

rodstored-72 · 02-03-2020, 11:11 AM

PONTIAC,
did not know that... for extra measure could a person use threadlock to help with security for them??
I am finding that a thread gauge might be a good "tool" to go ahead & invest in...

**mongocanfly** · 02-03-2020, 02:02 PM

If you have lock nuts theres no need for thread locker

rodstored-72 · 02-04-2020, 10:42 AM

Mongo,
I didn't think about that.... good suggestion, I also like how they look too...

thanks!!

01-21-2020, 01:02 AM	#1
rodstored-72 chevy truck fan Join Date: Mar 2005 Location: Gilbert, arizona 85298 Posts: 2,008	brake booster question ok guys.. I give up I have looked & looked & I am not able to find what the nut size (mainly the stud size) is for the brake booster bracket. I had to replace the(6) nuts that hold the booster (bracket) to the firewall?? this could be a trivia question for Keith Seymore I bet!! thanks!! Last edited by rodstored-72; 01-21-2020 at 03:46 PM.

01-21-2020, 11:06 AM	#2
blazer2007 Registered User Join Date: Jan 2007 Location: vernon b.c. Posts: 3,022	Re: brake booster question for some reason mine were metric ,1980 truck

01-21-2020, 01:15 PM	#3
MikeB Senior Member Join Date: Jul 2000 Location: North Texas Posts: 3,597	Re: brake booster question Do you have a way to measure the stud diameter? My truck doesn't have a booster, but I'd suspect your threads are either 3/8-24, 3/8-16 or, if metric 8mmx1.25 or 8mmx1.00. I find thread gauges like these to be indispensable: __________________ Mike 1969 C10 LWB -- owned for 35 years. 350/TH350, 3.08 posi, 1st Gen Vintage Air, recent AAW wiring harness, 5-lug conversion, 1985 spindles and brakes. 1982 C10 SWB -- sold 1981 C10 Silverado LWB -- sold, but wish I still had it! 1969 C10 (not the current one) that I bought in the early 1980s. Paid $1200; sold for $1500 a few years later. Just a hint at the appreciation that was coming. Retired as a factory automation products salesman. Worked part-time over the years for an engine builder and a classic car repair shop. Member here for 24 years! This is the very first car/truck Internet forum I joined. I still used a dial-up modem back then! Last edited by MikeB; 01-21-2020 at 05:33 PM.

01-21-2020, 01:47 PM	#4
mongocanfly Post Whore Join Date: May 2015 Location: Alabama Posts: 14,670	Re: brake booster question Do you still have the nuts?...if so take them to fastenal or a bolt store Thread gauges like Mike showed really come in handy.. __________________ Mongo...aka Greg RIP Dad RIP Jesse 1981 C30 LQ9 NV4500..http://67-72chevytrucks.com/vboard/s...d.php?t=753598 Mongos AD- LS3 TR6060...http://67-72chevytrucks.com/vboard/s...34#post8522334 Columbus..the 1957 IH 4x4...http://67-72chevytrucks.com/vboard/s...63#post8082563 2023 Chevy Z71..daily driver

01-21-2020, 03:45 PM	#5
rodstored-72 chevy truck fan Join Date: Mar 2005 Location: Gilbert, arizona 85298 Posts: 2,008	Re: brake booster question mike, thanks!! I "think" I have a friend that has a thread gauge. No I do not have the the original nuts, i believe they might have been "tossed out" on accident. I wanted to clean the studs up but don't know the size to get to run over them & then replace the nuts with new.... It was my bad during the teardown process- I meant to keep them though....aarrrggg I tried looking in some e-manuals & such, but to know avail......

01-26-2020, 04:53 PM	#6
rodstored-72 chevy truck fan Join Date: Mar 2005 Location: Gilbert, arizona 85298 Posts: 2,008	Re: brake booster question well, I dug through more boxes and finally found them. I do believe they are metric, but the nuts seem to “feel” good in my 3/8-16 threader. so, i chased them and then proceeded to install. i still would like to know the answer.... hoping this might be worthy of keith seymore to chime in... LOL thanks, I will update my thread with pics too

02-02-2020, 02:59 PM	#7
Pontiac1976 Registered User Join Date: Oct 2015 Location: Ottawa, Ontario, Canada Posts: 766	Re: brake booster question The nuts are crushed a little keep them from backing off (so the holes are not totally round) If you can't factory use plastic insert nut( locking nuts) If you have headers use lock washers nuts. Or there is type that has 4 small cuts at the top of the nut squeeze lock. I think 3/8 studs, yes thread gauges come in handy more then you think. __________________ 1977 REG cab Long Bed with a 1984 Front Clip, 82 305 .60 over 9.0.1 flat top pistons, 4bbl, TH350, w/84 SS-intake & cam , w/ 1977 big block rad, 1975 gear box, 1984 master w/ metric fittings top & SAE fitting @ portion block, 1975 3.42 gear open diff. Duel 77-87 Factory air cleaner, duel inlet from rad support . Down sized 9' to new 8' Steel flat bed Was a 77 454 w/308 gear. Taken out 550 lbs. up front with motor clip change.

02-03-2020, 11:11 AM	#8
rodstored-72 chevy truck fan Join Date: Mar 2005 Location: Gilbert, arizona 85298 Posts: 2,008	Re: brake booster question PONTIAC, did not know that... for extra measure could a person use threadlock to help with security for them?? I am finding that a thread gauge might be a good "tool" to go ahead & invest in...

02-03-2020, 02:02 PM	#9
mongocanfly Post Whore Join Date: May 2015 Location: Alabama Posts: 14,670	Re: brake booster question If you have lock nuts theres no need for thread locker __________________ Mongo...aka Greg RIP Dad RIP Jesse 1981 C30 LQ9 NV4500..http://67-72chevytrucks.com/vboard/s...d.php?t=753598 Mongos AD- LS3 TR6060...http://67-72chevytrucks.com/vboard/s...34#post8522334 Columbus..the 1957 IH 4x4...http://67-72chevytrucks.com/vboard/s...63#post8082563 2023 Chevy Z71..daily driver

02-04-2020, 10:42 AM	#10
rodstored-72 chevy truck fan Join Date: Mar 2005 Location: Gilbert, arizona 85298 Posts: 2,008	Re: brake booster question Mongo, I didn't think about that.... good suggestion, I also like how they look too... thanks!!



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