Yedi Posted February 16, 2011 Report Share Posted February 16, 2011 Ok From what I can tell I have some now severe issues with my poor old girl lol Brakes used to be hard to push usually almost all the way as well to get it to stop (thinking booster wasn't activating) Occasionally would suddenly actually have normal brakes and about give me whiplash had a front flat the other day threw a belt felt like truck was going to fly apart stopped fine but middle of LONG trip changed tire on my way went to get off exit and wow NO breaks at all (thank god for e-brake or I would not be posting) guy I know races stock car looked it had lost the fluid though now it is not going down since we filled it and brakes on one test drive took about a block to slow down from 25 mph to stop (he is suggesting master cylinder ) I ordered both newish well re-manufactured so almost new and mc rushed shipping (i will find another arm and leg somewhere) Besides obviously we are going to need to bleed the brakes anyone got any suggestion for this? I also think that someone had possibly replaced the mc with too small one at some time . I have read every break forum here dealing with 720 brakes and saw it originally had a 15/16 bore the one in the truck says 7/8 not a big difference though I hope because I ordered a replacement and MOST the ones listed said they were manufacturer oem equivalents but 7/8 was listed for almost all of them so did the 720 have a 7/8 mc or actually a 15/16 and if so will a new 7/8 actually do the job? Quote Link to comment
SoCaLKiDz Posted February 16, 2011 Report Share Posted February 16, 2011 Well there could be a vaccum leak or missing hose coming off the booster towards the firewall.. Quote Link to comment
datzenmike Posted February 16, 2011 Report Share Posted February 16, 2011 Before throwing money at it... The rear drums and e brake should be adjusted to reduce peddle travel. Inspect the shoes and the front pads, they may be worn out. You may also have a leak in the rears or the master is empty. Replacing the master won't fix this. Quote Link to comment
Yedi Posted February 16, 2011 Author Report Share Posted February 16, 2011 Has new brakes and cylinders rear earlier this year well last year new shoes front as well but the mc was leaking slowly and like I said sometimes it would be hard and sometimes soft for the brakes then NONE except ebrake after the flat and I was told the shoes in the 720's were self adjusting in the rear so shouldn't be that problem either Quote Link to comment
SoCaLKiDz Posted February 16, 2011 Report Share Posted February 16, 2011 Look under the hood at the booster. There should be a black vaccum hose leading up by the 3 steel hard lines. The black rubber hose should go into a "T" shaped metal thing (drawing a blank on what it is called) now take a oic of that and post it. There schould be 2 other hoses ran off that line.. Quote Link to comment
Yedi Posted February 16, 2011 Author Report Share Posted February 16, 2011 Look under the hood at the booster. There should be a black vaccum hose leading up by the 3 steel hard lines. The black rubber hose should go into a "T" shaped metal thing (drawing a blank on what it is called) now take a oic of that and post it. There schould be 2 other hoses ran off that line.. Unfortunately I have no idea how to post a pick of it I could take some with my phone but no idea how top post them can't even transfer with this pos phone if I new someone with a verizion phone I could send them to them and have them post them via pic mail lol But otherwise I am messed. Quote Link to comment
datzenmike Posted February 17, 2011 Report Share Posted February 17, 2011 Has new brakes and cylinders rear earlier this year well last year new shoes front as well but the mc was leaking slowly and like I said sometimes it would be hard and sometimes soft for the brakes then NONE except ebrake after the flat and I was told the shoes in the 720's were self adjusting in the rear so shouldn't be that problem either All this info should really have been put in the first post. Leaking MC would be a give away that there is something wrong with it. Like the manual adjusters the self adjusters will only work if the adjusting wheel isn't seized. If new brakes were installed I assume they checked that. Check the build date on the door jam. If built between June and Nov '82 it should have a 7/8" master. Dec '82 and on were 15/16". Or if your stock motor is a Z22 it should have the 7/8" all Z24s had the larger 15/16". Quote Link to comment
wayno Posted February 17, 2011 Report Share Posted February 17, 2011 Hi there Yedi, You have a 1982 datsun 720 with a SD22 diesel engine, correct? Your vacuum is created by a vacuum pump on the back of the alternator, that pump does only one thing, it creates vacuum for the power brakes, there are no tees in that vac. line, it goes to the power brake booster only. If it is a stock rearend, it does not have self adjusters for the rear brakes, they came out with self adjusting in 1984 or 85? Datzenmike?? It is easy to test the vac. pump, pull the hose off the powerbrake booster, start the engine, and put your finger on the end of the hose, is there vacuum? If not, you do not have power brakes. If your M/C leaks, buy a new one, IT IS NOT WORTH SCREWING AROUND WITH A LEAKY MASTER BRAKE CYLINDER, IN THE LONG RUN YOU WILL LOSE YOUR ASS, AND MAYBE KILL SOMEONE ELSE ALSO. wayno Quote Link to comment
datzenmike Posted February 17, 2011 Report Share Posted February 17, 2011 Yeah I checked, the self adjusters started being used mid year '81. Quote Link to comment
wayno Posted February 17, 2011 Report Share Posted February 17, 2011 Yeah I checked, the self adjusters started being used mid year '81. On a 720? I have bought a lot of 720s the last 5 years, a couple of them were 82s and the only one with rear self adjusters was a 84 I beleave, with the big front bumper and taller front turn signal indicators. Was it an option on the earlier models? Quote Link to comment
SoCaLKiDz Posted February 17, 2011 Report Share Posted February 17, 2011 In this situation i would listen to datzenmike and wayno.. They will have wayyyy better understanding of what going on .... unfortunely :rolleyes: :lol: Quote Link to comment
datzenmike Posted February 17, 2011 Report Share Posted February 17, 2011 In this situation i would listen to datzenmike and wayno.. They will have wayyyy better understanding of what going on .... unfortunely :rolleyes: :lol: I'll check tonight when I get home. I was told '82, maybe mid year which would also be when the Z24 and larger master came out, but checking through the parts I found an adjuster mechanism listed for '81. I understand the axles were also longer to make room for the adjusters. I may have typed in the wrong year. Quote Link to comment
SoCaLKiDz Posted February 17, 2011 Report Share Posted February 17, 2011 I thought the Z24 came out in 84'? i could be wrong. An i have an 81' 720... What are the adjusters for? Quote Link to comment
datzenmike Posted February 17, 2011 Report Share Posted February 17, 2011 I thought the Z24 came out in 84'? i could be wrong. An i have an 81' 720... What are the adjusters for? I think Dec or around mid year of '82 the Z24 was brought out. The adjusters are automatic. Every time the brakes are applied there is a cable that pulls up on the adjuster which ratchets the star wheel tighter. The shoes have to have enough slack (wear) so that the movement is enough to reach the next tooth. When it does it toggles the adjuster ahead and removes a small bit of shoe travel, just enough so the adjuster can't quite reach then ext tooth. Well at least untill there is enough brake wear to cause enough travel. Quote Link to comment
SoCaLKiDz Posted February 17, 2011 Report Share Posted February 17, 2011 So what are the main differences in the Z22 and the Z24? Sorry about thread jacking:( i always wanted to know tho Quote Link to comment
Yedi Posted February 17, 2011 Author Report Share Posted February 17, 2011 I thought I had a sd22 LOL the diesel Quote Link to comment
datzenmike Posted February 18, 2011 Report Share Posted February 18, 2011 I thought I had a sd22 LOL the diesel Sorry Diesel. Yeah it looks like 2wd up to 11 '81 did not have the self adjusters. All SD22 and Z22 2wd from 12 '81 on were supposed to have them. Quote Link to comment
SoCaLKiDz Posted February 18, 2011 Report Share Posted February 18, 2011 So is it a diesel then? Quote Link to comment
datzenmike Posted February 18, 2011 Report Share Posted February 18, 2011 His profile says: Cars:1982 datsun 720 deisel Quote Link to comment
Yedi Posted February 19, 2011 Author Report Share Posted February 19, 2011 yes and it seems both were bad replaced the mc have breaks now . just harder to push down than a pogo stick for a 600 lb person lol.booster comes in next week. Quote Link to comment
Yedi Posted February 28, 2011 Author Report Share Posted February 28, 2011 well booster came in replaced much better now ... little soft guess when the weather is good will have to jack it up and do the last place to bleed that little box in the middle under the truck lol not doing that in a foot of snow lol Quote Link to comment
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