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Re: 1978 Chevy K20 longbed with nearly 500,000 miles! LS Swap begins!
Getting down to the little things now!
Ran the vent lines for the fuel tanks and rear axle. https://i.postimg.cc/vZHH6kFH/IMG-5670.jpg Ran the harness for the new license plate lights. https://i.postimg.cc/0yW5GnPG/IMG-5671.jpg Adapter for the 7 pin trailer connector. https://i.postimg.cc/8C7pZvz2/IMG-5675.jpg https://i.postimg.cc/TPBRFPyp/IMG-5676.jpg Made an interior harness for the trailer brake controller that tied into the brake light switch. https://i.postimg.cc/XJFVb0Fx/IMG-5678.jpg Made a circuit breaker block for the power feeds for the 7 pin and brake controller. https://i.postimg.cc/NFcQGPkt/IMG-5679.jpg Driver front brake line was pretty rusty looking at the fitting, so I made a replacement. https://i.postimg.cc/d3jwhm5y/IMG-5680.jpg Perfect fit! https://i.postimg.cc/2jQz9rCS/IMG-5682.jpg https://i.postimg.cc/8PTTq9CB/IMG-5683.jpg |
Re: 1978 Chevy K20 longbed with nearly 500,000 miles! LS Swap begins!
Started on the rear brakes today. Didn’t make it that far, mostly because I could’ve sworn up and down that I had 13” brakes, but turns out that I actually had 11” rears. Instead of returning all the parts and going with 11”, I’m going to locate the 13” backing plates and end up with a better set of brakes!
The original ones were destroyed… https://i.postimg.cc/XNp84FfD/IMG-5686.jpg https://i.postimg.cc/WpC733Sp/IMG-5687.jpg https://i.postimg.cc/jdf4JbkH/IMG-5688.jpg Both wheel hubs stripped. Probably going to take these into town with me and have them hot tanked since they’re pretty nasty. https://i.postimg.cc/P5kzWRBB/IMG-5694.jpg https://i.postimg.cc/R0S78nCd/IMG-5695.jpg |
Re: 1978 Chevy K20 longbed with nearly 500,000 miles! LS Swap begins!
That's the 11in "oil bath" RPO code, haha
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Re: 1978 Chevy K20 longbed with nearly 500,000 miles! LS Swap begins!
Yeah no kidding.
I’m not sure if I mentioned this earlier, but for some reason I’ve had an interference issue with the hydroboost and master cylinder. I’ve had everything apart several times and can’t find any issues, so since I’m into the brakes now, I decided to just make a shim to gain the proper clearance back. Sheet of aluminum measuring .058”. I used an SBC thermostat housing gasket as a template and just moved the holes out a little bit for the booster bolt pattern. https://i.postimg.cc/x1DD4Tnp/IMG-5697.jpg Perfect fit! With the shim in place, I can measure .007” clearance now between the pin and piston. https://i.postimg.cc/8CT8TKFh/IMG-5724.jpg Still not sure why there was a clearance issue, but this turned out to be a nice solution! https://i.postimg.cc/V6H2BzKR/IMG-5725.jpg |
Re: 1978 Chevy K20 longbed with nearly 500,000 miles! LS Swap begins!
Interesting, so was it applying slight pressure to the MC without that shim?
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Re: 1978 Chevy K20 longbed with nearly 500,000 miles! LS Swap begins!
Yeah, noticeable enough that I could slide the master cylinder onto the booster studs and seat it by hand and have nearly a washers’ width of gap between the two flanges once the pin touched the piston. I could feel it pushing the piston in if I pushed the master cylinder the final bit manually.
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Re: 1978 Chevy K20 longbed with nearly 500,000 miles! LS Swap begins!
Rear wheel hubs after a couple rounds in the hot tank and a fresh coat of paint!
https://i.postimg.cc/V6wt1shk/IMG-5731.jpg |
Re: 1978 Chevy K20 longbed with nearly 500,000 miles! LS Swap begins!
New bearings installed in the wheel hubs!
https://i.postimg.cc/NfHFFRd4/IMG-5800.jpg I need to pick up a press to install the wheel studs through the hubs and drums. https://i.postimg.cc/Bnf6KtyG/IMG-5801.jpg I scored a pair of early 13” backing plates! These were hard to find because they used the bolt in style parking brake cables. https://i.postimg.cc/VNYkKpmG/IMG-5966.jpg Old junk removed! https://i.postimg.cc/43BNqP3J/IMG-5971.jpg https://i.postimg.cc/G2thCDBv/IMG-5965.jpg Brakes completely redone on passenger side! https://i.postimg.cc/VvbfScW6/IMG-5969.jpg https://i.postimg.cc/xCZjTdHh/IMG-5968.jpg And brakes completely redone on the drivers side! https://i.postimg.cc/4nkJVFW1/IMG-5970.jpg https://i.postimg.cc/pVg8sW7s/IMG-5973.jpg https://i.postimg.cc/wxtL5yWt/IMG-5972.jpg |
Re: 1978 Chevy K20 longbed with nearly 500,000 miles! LS Swap begins!
Brass hammer and punch will get those studs driven in, but a press is nice to have as well.
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Re: 1978 Chevy K20 longbed with nearly 500,000 miles! LS Swap begins!
Looking good!
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Re: 1978 Chevy K20 longbed with nearly 500,000 miles! LS Swap begins!
I had quite the lame weekend on this one. I finally got the parking brake cables in, and intended on bleeding the brakes and installing the wheels, and maybe even getting a test drive in! The front parking brake cable went well, but the intermediate one turned out to be for a shortbed wheelbase, so I ordered the next size up.
Then, bled the rear brakes only to not get that great of pressure out to the rear. After vacuum bleeding the rears, and various troubleshooting, I could sometimes get pressure at the rear, and sometimes not. The proportioning valve was replaced quite a few years ago, but it’s acting like it’s sticking to one side now. I ordered up a new one and will try again next week! |
Re: 1978 Chevy K20 longbed with nearly 500,000 miles! LS Swap begins!
Alright, after messing with it for a bit, this is where I’m at.
Went to adjust the rear shoes. I can tell the new drums are slightly out of round, as they drag slightly on the shoes on only about 1/2 of the drum. Both sides do this. However, at the adjustment sight windows at the bottom of the backing plates, the shoes have a small gap and don’t touch the drum. I could likely crank on the adjuster and force them to, but the drum would be locked up. It feels like the shoes touch the drum at the top before the bottom. The driver side is slightly better than the passenger side. Currently, I have it adjusted where there is some slight drag. After attempting to bleed the brakes, the front worked fine. I could not get consistent pressure to the rear, although the rear brakes did work really well once sporadically. I determined the proportioning valve was shot. Ordered a new proportioning valve and the bleed lock tool for it. Installed both of those and had better results, but still inadequate pressure in the rear. Warrantied out the brand new master cylinder for another one and rebled the system. Now I have good pressure to the rear. However, the hose from the frame to the axle was machined incorrectly, and the hard line wouldn’t seat and kept leaking. This damaged the new passenger side hard line. I warranted out the hose and reflared the hard line and replaced the fitting. Went to install and the drivers side threads pulled right out without even tightening down, damaging the driver side hard line. Replaced the hose again, with a different brand, and reflared the other hard line and replaced that fitting. Installed the new line and rebled the system again. Removed all the air and the pedal feels good. However, if I have the pedal pressed I can still turn the rear drums by hand. They definitely drag more than what my adjustment was, but they definitely don’t work. Front seems to lock up solid and work great. For an extra brain scratcher, if I manually pull the parking brake cables by hand, both rear brakes will work perfectly via the parking brake. Not sure what the issue is, but I think I’ll have to dive back inside one of these upcoming weekends. At least I had some help, lol. https://i.postimg.cc/59gtYDnW/IMG-6590.jpg https://i.postimg.cc/SRgQBzJx/IMG-6576.jpg This was…interesting. https://i.postimg.cc/65Qpdzm2/IMG-6591.jpg New proportioning valve installed https://i.postimg.cc/sD0DKSkn/IMG-6592.jpg New wheels mounted in the front! https://i.postimg.cc/tJvySQM1/IMG-6604.jpg https://i.postimg.cc/kMTnXKgn/IMG-6605.jpg |
Re: 1978 Chevy K20 longbed with nearly 500,000 miles! LS Swap begins!
Brakes can be very frustrating!
Sounds like the drums need turned to true and balanced before you chase any other issues. Or just swap to rear discs? |
Re: 1978 Chevy K20 longbed with nearly 500,000 miles! LS Swap begins!
Had to at least see what the wheels looked like on it!
https://i.postimg.cc/PJ9DJDLp/IMG-7100.jpg I’ve been messing with the brakes more on and off. Ended up taking the drum assemblies apart to double check that everything was okay. Shoes appear to fit perfect. https://i.postimg.cc/3rcmnsL8/720314...D3-F789-E9.jpg https://i.postimg.cc/ZKv3gwgr/720314...ACFC34-F62.jpg I did notice that the shoe material stuck out past the metal portion, so I ground that down in case it was causing the shoe to not sit flat on the backing plate. https://i.postimg.cc/pLN8tDb3/IMG-7558.jpg https://i.postimg.cc/jSzfqLR2/IMG-7557.jpg Still not satisfied with the brake performance, I hypothesized that I needed a K30 master cylinder instead of the K20 unit, which gave me 1-5/16” bore instead of the 1-1/4” bore, meaning I would have a higher volume output, stiffer pedal feel, and less pedal travel, which is what I think this truck needs. So I picked up a K30 unit. https://i.postimg.cc/m2yWmnq6/IMG-7552.jpg Painted! https://i.postimg.cc/K8cSwNhc/IMG-7553.jpg Bench bled the unit https://i.postimg.cc/7ZB8k2q3/IMG-7554.jpg Just out of curiosity for comparison - it appears the K20 and K30 units are slightly different depths. https://i.postimg.cc/v8Wmd3k5/IMG-7555.jpg https://i.postimg.cc/FsNHF0X8/IMG-7556.jpg After all of this, I’m still not completely satisfied. I’ve also determined that the hydroboost unit doesn’t appear to be always working as it should, so I’ve ordered a new replacement. Unfortunately, it has an up to 90 day lead time. |
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