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| Upgrade to big bolt pattern and 4 wheel disk project https://www.slantsix.org/forum/viewtopic.php?t=63829 |
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| Author: | wjajr [ Mon Jul 15, 2019 12:12 pm ] |
| Post subject: | Upgrade to big bolt pattern and 4 wheel disk project |
Today UPS dropped off a set of 15x7 Rallye wheels, lug nuts, center caps, and a pair of QA1 upper tubular control arms. As Ant would say; the old CAP tubular ACA are going in the bin. I have had them on the car for eleven years, and thinking back there was not many after market UCA out there to be had. These had two major drawbacks, frigging squeaky bushings, and the ball joint dust boot would not seal to the arm requiring constant greasing every 1000 miles or less, and one lesser being no bump stop landing. Compared to the QA1 units they are flimsy toys. So I'm happy with this advance in tubular A arms in the last 10 years for A Body cars. I have on the way a set of adjustable strut rods to aid getting castor settings above +1*. The QA1 arms have + 3*, but my car has always resisted obtaining positive castor. Hopefully the new UCA's and Strut rods will get this car into the positive. I have been trying to communicate via e mail and telephonicly with Doc Diff since the 4th, nothing but crickets. Hopefully he is on vacation. I had questions about how to determine if my 8 3/4" Auburn Suregrip rear axle of which I'm fairly sure is bone stock A Body will be compatible with his axles. It has 1 3/4" x 10" rear drums, so it must have come from an early V8 car; it looks like the Doc's axles are to be used with 2" x 10" drums found on the later A bodies. Anyone know how much stopping power difference is between front disk's stage 1(10.95") and stage 2 (11.75")? Both sage 1 & 2 are listed to be paired to the same 10.7" rear disk brake kit. I'm also thinking about adding power assist to the project. There may be a low vacuum problem at idle with the new cam installed last year. From what I can glean a power booster ideally likes to see 18" Hg at idle. A quick Vacuum study yielded the following: in Park 12" Hg @ 800 rpm in Drive with brake on: 8" Hg at 650 rpm; 12" Hg at 1000rpm. no brake, no load on engine: 14"Hg at 1000 rpm 15" Hg at 1200 rpm 17" Hg at 1500 rpm 17.5 Hg at 1600 rpm 18"Hg. over 1800 rpm Let off throttle, car not in gear gives 20" to 22" Hg At constant 45 mph turning 2500 rpm produces 15" to 16" Hg I'm thinking that a vacuum storage can may need to be added. Anyone have input to the booster addition? I'll have to make up my mind before ordering master as cylinder's bore size needs to be selected. |
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| Author: | Dart270 [ Mon Jul 15, 2019 1:32 pm ] |
| Post subject: | Re: Upgrade to big bolt pattern and 4 wheel disk project |
Sounds like a great project. Here are a few thoughts: 1) I hate power brakes, so I would stay away from that. YMMV, however. 2) My experience has been that the 11.75" fronts are way better than 10.9". If you have the $$, then there is no decision here, IMHO. The pedal force is substantially reduced for the 11.75" system too - see point (1). 3) I will happily pay shipping if you want to send me those CAP UCAs. I may repurpose/modify them somehow... 4) Based on your pedal effort concerns, probably go with 1" or 15/16" bore MC. Avoid rebuilt parts store junk. If DrDiff has a good source, go with him. All the best, Lou |
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| Author: | slantzilla [ Mon Jul 15, 2019 4:46 pm ] |
| Post subject: | Re: Upgrade to big bolt pattern and 4 wheel disk project |
Didn't QA-1 buy out CAP? On the axles, Dr. Diff can set the bearing wherever it needs to be for the brake type you want. BBP axles normally are spaced for B/E body brakes. |
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| Author: | emsvitil [ Mon Jul 15, 2019 6:30 pm ] |
| Post subject: | Re: Upgrade to big bolt pattern and 4 wheel disk project |
From a leverage viewpoint 7.3% better (11.75/10.95) |
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| Author: | Danarchy [ Mon Jul 15, 2019 9:00 pm ] |
| Post subject: | Re: Upgrade to big bolt pattern and 4 wheel disk project |
I have had the QA1 UCA's on my car for about 3 years now (30K+ daily driver miles) and the poly bushings have been Silent! I greased them once because I was paranoid.(and they didn't even need grease!) I also have 11.75 disc conversion on front(all junk yard cobbled parts)[15x7 AR steel wheels] and a narrowed 8.8 ford rear end (also disc), and I have zero problems. (Well...minor electrical gremlins I'm dealing with!) 
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| Author: | wjajr [ Tue Jul 16, 2019 5:00 am ] |
| Post subject: | Re: Upgrade to big bolt pattern and 4 wheel disk project |
Thanks guys. The Doc answered my questions late yesterday. Order going in today, 11 3/4 front disk, manual brakes, rear stage 1/2 disks, and new large bolt pattern axles. Dart 270 PM me for CAP parts. Project won't start until all parts are on site, probably some time late next week. Bill |
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| Author: | jcc [ Tue Jul 16, 2019 10:43 am ] |
| Post subject: | Re: Upgrade to big bolt pattern and 4 wheel disk project |
What was the need for a rear disc solution? |
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| Author: | wjajr [ Sun Jul 21, 2019 7:00 am ] |
| Post subject: | Re: Upgrade to big bolt pattern and 4 wheel disk project |
Quote: What was the need for a rear disc solution?
67 Dart has small bolt pattern wheels & hubs.Later model 1973 and up as well as B and C body all use large bolt pattern. The hubs or steering knuckles the Doc sells are B/C body parts of a more robust construction than what was on A Bodies requiring larger lower ball joints and attaching bolts to be installed than the 10" K-H disks currently in use of which the spindles are worn allowing inner bearing race to rock on spindle. Out back I have expensive to replace skinny SBP 1 3/4" 10 drums for all intent and purposes are obsolite. Where my 14" Rallye wheels are beat and not so round anymore, tires need replacing, it's a good time to just update the rear axle as well. So new LBP axles, and 10.75" disks are going on the back matching the front upgrade, along with new larger Rallye wheels and fatter rubber. Decision was made to go with 15/16" bore non boosted master cylinder for easier brake application. This pile of new parts was a lot of dough, but I think the car will be much improved in ride and handling. Hopefully between the up to +3* caster correction UCA, and adjustable strut rods, I can easily get a good alignment for the first time in 10 years with plus a few degrees caster. Currently there is a lot of flexing and suspension vibrations, brake peddle pulsing, and bearing noise at certain speeds, and brakes could be a lot better even though I have front disks on it all ready. Strut rods show up Monday, so I'll probably rip into the front end right away. Bill |
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| Author: | wjajr [ Sat Jul 27, 2019 4:48 pm ] |
| Post subject: | Re: Upgrade to big bolt pattern and 4 wheel disk project |
Up Date: Early in the week I got the adjustable strut rods installed, and old front brakes removed, parts form Doc Diff arrived a day early on Thursday afternoon which I unpacked and sorted. Friday I started to install the equipment. Installation has taken longer than I thought, or I'm a lot slower than I used to be. There was some tedious prep work packing bearings, removing sub par races form disks making way for installation of Timpkin wheel bearings supplied by the Doc., cleaning areas where all these parts hang from. I was not familiar with the front single piston calipers, and the rear disk/caliper with E brake that works like what one would find on a Mopar mini van. As of tonight the car is still on stands, and sporting new big disks at all four corners. One problem popped up, I ordered new lug 1/2 x 20 acorn lug nuts, somehow probably due old atrophied brain left hand nuts arrived, Man, I hate working with old people. So the correct nuts are on the way, be here in two days, or so they say. Can't wait to drive this thing. |
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| Author: | wjajr [ Wed Jul 31, 2019 9:58 am ] |
| Post subject: | Re: Upgrade to big bolt pattern and 4 wheel disk project |
It's all together, brakes bleed, and here I sit waiting for the right handed lug nuts to arrive via USPO... After several rounds of bleeding I think all the air is out. However peddle is very spongy. Doc sent me 15/16 inch bore aluminum late 89's stile two stud master cylinder and conversion plate, and a little nub of neoprene to be used as a spacer to counter the added distance needed for push-rod for conversion plate. Some of the soft feel is probably due to the neoprene spacer. I wonder if I need to get an adjustable push rod, and ditch the neoprene nub? |
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| Author: | SpaceFrank [ Wed Jul 31, 2019 10:55 am ] |
| Post subject: | Re: Upgrade to big bolt pattern and 4 wheel disk project |
What does the neoprene nub look like? Does it just go over the end of the stock push rod? How does the push rod lock into the master? FWIW, I ordered the adjustable push rod when we converted to a 2-bolt master w/adapter plate (also from Doctor Diff), but I still haven't gotten around to installing it. I got the larger bore (1-1/32"?) master though, so the pedal is firm enough that the droop hasn't been a big problem. |
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| Author: | Dart270 [ Wed Jul 31, 2019 1:04 pm ] |
| Post subject: | Re: Upgrade to big bolt pattern and 4 wheel disk project |
I doubt I would ever use a piece of rubber in the path of applying force from pedal to master cylinder piston. I would buy or make an adjustable pushrod if the height is not right. I have done both... Lou |
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| Author: | wjajr [ Wed Jul 31, 2019 1:32 pm ] |
| Post subject: | Re: Upgrade to big bolt pattern and 4 wheel disk project |
The thickness of that conversion plate is 5/16th inch about the same at that neoprene nub. I don't have anything preventing push rod from being pulled out of master cylinder. |
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| Author: | Dart270 [ Wed Jul 31, 2019 2:32 pm ] |
| Post subject: | Re: Upgrade to big bolt pattern and 4 wheel disk project |
I also do not like the pullout issue. I make sure to have the donut in there to keep it from pulling out. Gotta be extra careful with the brake system. Dr Diff has the donuts and adj pushrods. Lou |
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| Author: | SpaceFrank [ Thu Aug 01, 2019 10:39 am ] |
| Post subject: | Re: Upgrade to big bolt pattern and 4 wheel disk project |
Quote: I also do not like the pullout issue. I make sure to have the donut in there to keep it from pulling out. Gotta be extra careful with the brake system. Dr Diff has the donuts and adj pushrods.
I agree completely with Lou. Locking the pushrod into the hole in the master cylinder piston is a safety feature; if it pops out you've got big problems. Also, the 5/16" of rubber between your pushrod and piston is probably the source of the spongy pedal feel.
Lou |
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