engine_ear
11-24-2014, 02:22 PM
I found this 1970 Pontiac Lemans Sport 400/TH400 over the mountains about three hours away; drove it home the following weekend. Pretty rough around the edges, but for the price and being a complete driver; it couldn’t be beat:
https://www.pro-touring.com/attachment.php?attachmentid=105660&stc=1
https://www.pro-touring.com/attachment.php?attachmentid=105676&stc=1
The apartment I was in had a one-car limit; so of course I sold my reliable daily driver and bussed into work from my apt while I drove this new toy around and dreamt of all the work I was going to do/skills I was about to learn. The first project I attempted after replacing the printed circuit board, radio, lights, speakers and other various non-functioning aesthetics was replacing the 2bbl. I did this at nights in my apt. parking lot so I wouldn’t get written up by apt. staff while they were present during working hours - car maintenance/work was not allowed in the apartment:
https://www.pro-touring.com/attachment.php?attachmentid=105661&stc=1
I only drove it a couple weeks with the new 4bbl before the pistons in the factory brakes started leaking and the car would pull terribly to one side after driving about 5 minutes. I presume this was from brake fluid seeping out over the shoes? Fortunately this occurred about the same time we bought our first house (with garage). Budget has always been a concern so I am constantly shopping for best deals while trying to upgrade components where feasible within my budget. I purchased a front disc brake conversion kit with 2” drop spindles from Jegs and new front suspension/bushings via Moog. Control Arms were out of the budget, but were cleaned up and painted:
https://www.pro-touring.com/attachment.php?attachmentid=105662&stc=1https://www.pro-touring.com/attachment.php?attachmentid=105663&stc=1
https://www.pro-touring.com/attachment.php?attachmentid=105664&stc=1
I just couldn’t get comfortable with the way the 2” drop made the front of the car sit; so I ordered some stock height front spindles and put them on in place of the 2" drop.
The disc brake kit came with an inline adjustable proportioning valve that I wasn’t convinced about and didn’t want to mess with; so I did some reading and ended up purchasing a combined proportioning valve from a 1972 gto for front disc applications:
https://www.pro-touring.com/attachment.php?attachmentid=105665&stc=1
'Inlinetube.com' and 'getdiscbrakes.com' offered a lot of useful information/support online that I referenced. I put in stainless steel brake line replacements throughout the whole car as well. I bought a double flaring kit and a line bender for a few of the lines; SS lines are ten times harder to bend than oem steel, fyi. I haven’t plumbed up any gauges to verify things are working exactly as they should, but as far as I can tell things are functioning well with the disc/drum setup.
I didn’t drive it long before I tore into the rear to replace the sh!tty factory air shocks that never held air and were never level. Out of curiosity I pulled the cover off the rear end to see exactly what I had in there – an open factory posi with 2.56 gear ratio….boo. So I began the substantial learning process of rebuilding the rear end:
https://www.pro-touring.com/attachment.php?attachmentid=105673&stc=1
https://www.pro-touring.com/attachment.php?attachmentid=105677&stc=1
https://www.pro-touring.com/attachment.php?attachmentid=105667&stc=1
I originally falsely identified the rear end as an 8.2” BOP 10 bolt because of the year/model of my car; but after taking into account the stamped code (help from and George Nenadovich at www.buickperformanceclub.com (http://www.buickperformanceclub.com/)) and noting the square lugs below the diff cover I was happy to discover I had an 8.5” 10 bolt:
https://www.pro-touring.com/attachment.php?attachmentid=105666&stc=1
(LK = 2.56 gear ratio, B = Buick Rear, manufactured on 271st day of 1971)
Meaning I now had access to a multitude of replacement parts. I’m not sure the history of how that rear (1971) ended up in the 1970 car; but would be curious to know how, or maybe a previous owner just blew up the original and this was an economical replacement. Regardless, I ended up getting 3.42 Richmond gears, installation kit, and an associated Yukon Dura-Grip carrier to spruce-up rear-end performance. After over 30 setup variations (my lack of experience made me ultra paranoid about my setup) I was at a gear pattern that made me content. I’m sure by many standards I still did something wrong along the way and I'm sure the pattern would be sub-par by some accounts; but I was so sick of popping that carrier out and taking the pinion gear in/out - I was ready to take it however it operated at my final setup. So time will tell what I did wrong in the setup process :) ; but for now I’m happy to have a setup that is working without noise and performs like night/day compared to the original:
https://www.pro-touring.com/attachment.php?attachmentid=105671&stc=1
https://www.pro-touring.com/attachment.php?attachmentid=105674&stc=1
https://www.pro-touring.com/attachment.php?attachmentid=105668&stc=1
Rear-end Rebuild Lessons Learned:
Segregate rear-end work from my work bench - I ended up doing other unrelated work and got my new gears all dirty – what a pain to meticulously clean up my new gears and re-clean the pumpkin.
Find a more efficient way to torque down the pinion gear nut for each new pinion shim setup when the rear is out of the car – had the rear on the floor and sandbags on one end so I could properly torque the pinion nut for each fitting. I just kept thinking, “There has got to be a better way to do this!” I have a feeling someone can recommend something that will just make me feel like an idiot….
Get a better installation kit with more/diverse pinion shims.
Get a better tool to create the temporary fitment pinion bearing. It took forever with my dremel to take out enough material to slide the fitment bearing off/on without hesitation.
Don’t take the backlash numbers from online instructions or ‘how-to’s’ for fact; use the numbers printed on the side of the ring gear. Don’t know why it took me until late in the setup to find/realize these values printed on the gear.
I also installed rear KYB gas shocks, polyurethane bushings, stainless rear brake lines, new rear flex line, and new Timken bearings all around. Control arms were out of the budget for now; but I took the stock arms out, cleaned/sanded them up, and shot them with Eastwood Chassis Paint to complete the rear-end finished look:
https://www.pro-touring.com/attachment.php?attachmentid=105669&stc=1
Once again, I didn’t like how low the car sat when finished; I understand its factory, but I think it just looks stupid when the back-end is a good inch/two lower than the front. I think most people will say to lower the front to level the ride - but I didn’t want to do that either. So I picked up rear heavy duty springs that I understand were stock in El-Caminos which only helped about ½" to 1" to level the ride height. Then I picked up these rubber doughnuts the springs seat into. Looks like *****; I figure it is a temporary solution. Maybe someone can suggest ideas as to how to level the ride properly:
https://www.pro-touring.com/attachment.php?attachmentid=105675&stc=1
I just couldn’t find a better way to do this. Someone out there may have some recommendations? The final height reflects the rear about ¼” higher than the front, and looks good to me:
https://www.pro-touring.com/attachment.php?attachmentid=105670&stc=1
Now that I am done with the rear, my speedometer is off and I am left wondering what other adjustments must be made with new gears/posi? Driveline balancing? Etc.? ….. anyone?
https://www.pro-touring.com/attachment.php?attachmentid=105660&stc=1
https://www.pro-touring.com/attachment.php?attachmentid=105676&stc=1
The apartment I was in had a one-car limit; so of course I sold my reliable daily driver and bussed into work from my apt while I drove this new toy around and dreamt of all the work I was going to do/skills I was about to learn. The first project I attempted after replacing the printed circuit board, radio, lights, speakers and other various non-functioning aesthetics was replacing the 2bbl. I did this at nights in my apt. parking lot so I wouldn’t get written up by apt. staff while they were present during working hours - car maintenance/work was not allowed in the apartment:
https://www.pro-touring.com/attachment.php?attachmentid=105661&stc=1
I only drove it a couple weeks with the new 4bbl before the pistons in the factory brakes started leaking and the car would pull terribly to one side after driving about 5 minutes. I presume this was from brake fluid seeping out over the shoes? Fortunately this occurred about the same time we bought our first house (with garage). Budget has always been a concern so I am constantly shopping for best deals while trying to upgrade components where feasible within my budget. I purchased a front disc brake conversion kit with 2” drop spindles from Jegs and new front suspension/bushings via Moog. Control Arms were out of the budget, but were cleaned up and painted:
https://www.pro-touring.com/attachment.php?attachmentid=105662&stc=1https://www.pro-touring.com/attachment.php?attachmentid=105663&stc=1
https://www.pro-touring.com/attachment.php?attachmentid=105664&stc=1
I just couldn’t get comfortable with the way the 2” drop made the front of the car sit; so I ordered some stock height front spindles and put them on in place of the 2" drop.
The disc brake kit came with an inline adjustable proportioning valve that I wasn’t convinced about and didn’t want to mess with; so I did some reading and ended up purchasing a combined proportioning valve from a 1972 gto for front disc applications:
https://www.pro-touring.com/attachment.php?attachmentid=105665&stc=1
'Inlinetube.com' and 'getdiscbrakes.com' offered a lot of useful information/support online that I referenced. I put in stainless steel brake line replacements throughout the whole car as well. I bought a double flaring kit and a line bender for a few of the lines; SS lines are ten times harder to bend than oem steel, fyi. I haven’t plumbed up any gauges to verify things are working exactly as they should, but as far as I can tell things are functioning well with the disc/drum setup.
I didn’t drive it long before I tore into the rear to replace the sh!tty factory air shocks that never held air and were never level. Out of curiosity I pulled the cover off the rear end to see exactly what I had in there – an open factory posi with 2.56 gear ratio….boo. So I began the substantial learning process of rebuilding the rear end:
https://www.pro-touring.com/attachment.php?attachmentid=105673&stc=1
https://www.pro-touring.com/attachment.php?attachmentid=105677&stc=1
https://www.pro-touring.com/attachment.php?attachmentid=105667&stc=1
I originally falsely identified the rear end as an 8.2” BOP 10 bolt because of the year/model of my car; but after taking into account the stamped code (help from and George Nenadovich at www.buickperformanceclub.com (http://www.buickperformanceclub.com/)) and noting the square lugs below the diff cover I was happy to discover I had an 8.5” 10 bolt:
https://www.pro-touring.com/attachment.php?attachmentid=105666&stc=1
(LK = 2.56 gear ratio, B = Buick Rear, manufactured on 271st day of 1971)
Meaning I now had access to a multitude of replacement parts. I’m not sure the history of how that rear (1971) ended up in the 1970 car; but would be curious to know how, or maybe a previous owner just blew up the original and this was an economical replacement. Regardless, I ended up getting 3.42 Richmond gears, installation kit, and an associated Yukon Dura-Grip carrier to spruce-up rear-end performance. After over 30 setup variations (my lack of experience made me ultra paranoid about my setup) I was at a gear pattern that made me content. I’m sure by many standards I still did something wrong along the way and I'm sure the pattern would be sub-par by some accounts; but I was so sick of popping that carrier out and taking the pinion gear in/out - I was ready to take it however it operated at my final setup. So time will tell what I did wrong in the setup process :) ; but for now I’m happy to have a setup that is working without noise and performs like night/day compared to the original:
https://www.pro-touring.com/attachment.php?attachmentid=105671&stc=1
https://www.pro-touring.com/attachment.php?attachmentid=105674&stc=1
https://www.pro-touring.com/attachment.php?attachmentid=105668&stc=1
Rear-end Rebuild Lessons Learned:
Segregate rear-end work from my work bench - I ended up doing other unrelated work and got my new gears all dirty – what a pain to meticulously clean up my new gears and re-clean the pumpkin.
Find a more efficient way to torque down the pinion gear nut for each new pinion shim setup when the rear is out of the car – had the rear on the floor and sandbags on one end so I could properly torque the pinion nut for each fitting. I just kept thinking, “There has got to be a better way to do this!” I have a feeling someone can recommend something that will just make me feel like an idiot….
Get a better installation kit with more/diverse pinion shims.
Get a better tool to create the temporary fitment pinion bearing. It took forever with my dremel to take out enough material to slide the fitment bearing off/on without hesitation.
Don’t take the backlash numbers from online instructions or ‘how-to’s’ for fact; use the numbers printed on the side of the ring gear. Don’t know why it took me until late in the setup to find/realize these values printed on the gear.
I also installed rear KYB gas shocks, polyurethane bushings, stainless rear brake lines, new rear flex line, and new Timken bearings all around. Control arms were out of the budget for now; but I took the stock arms out, cleaned/sanded them up, and shot them with Eastwood Chassis Paint to complete the rear-end finished look:
https://www.pro-touring.com/attachment.php?attachmentid=105669&stc=1
Once again, I didn’t like how low the car sat when finished; I understand its factory, but I think it just looks stupid when the back-end is a good inch/two lower than the front. I think most people will say to lower the front to level the ride - but I didn’t want to do that either. So I picked up rear heavy duty springs that I understand were stock in El-Caminos which only helped about ½" to 1" to level the ride height. Then I picked up these rubber doughnuts the springs seat into. Looks like *****; I figure it is a temporary solution. Maybe someone can suggest ideas as to how to level the ride properly:
https://www.pro-touring.com/attachment.php?attachmentid=105675&stc=1
I just couldn’t find a better way to do this. Someone out there may have some recommendations? The final height reflects the rear about ¼” higher than the front, and looks good to me:
https://www.pro-touring.com/attachment.php?attachmentid=105670&stc=1
Now that I am done with the rear, my speedometer is off and I am left wondering what other adjustments must be made with new gears/posi? Driveline balancing? Etc.? ….. anyone?