Disc Brake Conversion

Drums, discs and conversions - they're all here.

Disc Brake Conversion

Postby dan » Mon Jun 21, 2004 2:53 pm

I'm back thinking about doing this again...

Does anyone know if there's a firm that supplies a "kit" (for lack of a better term) that has everything necessary to do a drum to disc conversion on the front?

I also seem to recall the conversion requiring different front spindles?

Does it require a different master cylinder as well (I have the original "tandem" design).

I'd hate the thought of having to pick up another parts car... :(

Thanks!
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Postby Herbytoy » Mon Jun 21, 2004 4:54 pm

I'm planning on doing this conversion on my 62 soon. I have collected the parts (plus many duplicates) over the years.

It does require different spindles. The best way, according to Frank C. is to swap the the a-arm, king pin and spindle (w/the brakes of course).

You can use the same MC but they are a different bore (3/4 vs 7/8?).
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Postby dan » Mon Jun 21, 2004 5:34 pm

I thought the different master cylinder bores would mean different pedal effort?

Maybe not a big deal for only an extra 1/8 inch dia?

My other issue is I rebuilt the front suspension not that long ago (at least in miles). If I have to do it all again, it may be worth it, but I'm sensing I may have another parts car in my future...

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Postby Herbytoy » Mon Jun 21, 2004 6:36 pm

Bummer. Well at least the a-arm bushings/bolts and trunion bush is the same. Unfortunately the kingpin is different and is most of the rebuild cost.

I've seen this "conversion" pop up on e-bay from time to time. I think one of the Brit parts guys that offer the whole thing less rotors and calipers for around $300. I think that's rebuilt as well.

I don't know if you have "pick-n-pull" type yards near you but Midgets show up in mine occasionally.
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Postby Herbytoy » Wed Jun 23, 2004 10:25 am

Here's part of the swap on e-bay. Disc Kit

Of course you still need the hubs.
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Postby Paul H » Wed Jun 23, 2004 11:03 am

I don't know what the parts prices are like in the States, but in the UK, the brake discs are less than £15 each, so it isn't really worth the cost or effort skimming rusty ones like those in the ebay auction.

Dan, what's wrong with another parts car? Lots and lots of goodies for minimal cost! (The parts car for my Volvo Amazon daily driver cost only £70, which was £10 less than a replacement windscreen, and yes, the screen on it was in perfect condition :D )

It should supply all the bit you'll need for the brake conversion (or serviceable exchange units), and if you get a 1275, you'll also get the later separate master cylinders (I dislike the paired clutch / brake master cylinder, purely for engineering reasons) and of course, a 1275 engine & 'box :twisted:
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Postby dan » Wed Jun 23, 2004 12:02 pm

I agree Paul...no sense in buying junk rotors when you can buy new for not much more. (Makes you wonder though why this eBay seller has effectively half the brake conversion kit)...

A parts car may make sense (although I doubt my wife would agree with that statement). The issue for me is really one of space--I already have 4 engines and 5 gearboxes (or something like that) in the basement, along with another nose, and God knows what else, and I really don't have the garage space for another dismantling project (can't have the Jag out in the rain you know!) :)

Maybe a better alternative would be to find someone who's purchased a parts car and is willing to part (no pun intended) with the disc brake conversion bits...

Maybe I could swap 'em for a gearbox? (or an engine, or a starter, or some gauges, or....)

:)
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Postby SpridgetBoy » Tue Jul 13, 2004 4:27 pm

Call me a purist, but I still have my drums on my MkII and Bugeye. I keep them in good order and check the adjustment occasionally and have never had a problem. As light as these cars are, I find that the drums work fine when properly adjusted. I have autocrossed and did a few laps vintage racing with no problem.

Once while being the bunny in a hair-and-hound, a hub cap flew off just as I got to the end of the run. When I went to put it back on, the drum was almost red hot. That was after a few hours of relatively short bursts with hard braking. I found that I had adjusted the shoes on that corner a little tight and one was dragging helping to contribute to the extra heat. The other three were fine.

A friend asked to share my car at an autocross once and, when he was done driving, he commented that "those disks really slow these cars down fast". I looked over my glasses at him and responded that my car was stock. He gave me a funny look so I responded, "4 drums". He didn't believe me and had to look.

IMHO, if you are not racing hard where heat can be a problem, disks are really just a bragging thing to boost one's ego. Well adjusted drums are more than acceptable. Car manufacturers have been putting drums on cars for years and generally know how to design a set. Yes, disks are probably better technology, but are they needed around town? I can easily lock up all four wheels with my drums so why do I need them to lock up quicker on the front with disks? Locked wheels just slow down your braking ability, that's why we now have anti-lock systems!! Later, SpridgetBoy
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Postby Paul H » Thu Jul 15, 2004 11:04 am

I can't comment on how it is in the States, but on this side of the pond, front disc brake conversions are seen as a desirable feature, for safety reasons (rather than as a 'boy-racer' thing) especially for everyday use. When in 'as new' condition, and properly adjusted, drums might be able to stop the car quickly, but drums won't resist brake fade anywhere near as well as disc brakes.
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Postby SpridgetBoy » Thu Jul 15, 2004 5:34 pm

Yeah, I know the brake fade thing is the biggest argument in making the change. But like I said, I drove extremely aggressive for a couple of hours and got one front drum almost red hot (I couldn't touch it and my nice black paint was pealing off) and I could still lock up the wheels at the end if I stood on the peddle a little (with all the daily driving and autocrossing on tight courses that I used to do, I got good at "feathering" the brakes without locking them up). The few times that I had to drive through water deep enough to get into the drums is the only time the brakes didn't want to work but I was going very slow at the time.

All I am saying is don't feel like you have to change to disks because everybody else is. My MkII was very original when I got it and I will never change it. My Bugeye has had lots of mods before I got it so it isn't as original. I am building a 1275 and a ribcase for it now and will probably put disks on it, a roll bar behind the seats, a sway bar up front, and I have a panhard rod for the rear.

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Postby dan » Thu Jul 15, 2004 9:33 pm

I can speak personally for brake fade with the drums (read my post in the "What's the dumbest thing?" thread in stories :oops: ) but the bottom line is after some "spirited" TSD rallye driving, I had no way to stop the car after I crested a hill around 70 MPH (stood on the pedal for all I was worth).

Having said that, drums have always worked great for me the rest of the time (LOTS of autocrosses included).

Be interesting to see how the drums perform on the track (but they won't let me vintage race without a roll bar--probably a good thing :wink: )

Still a tough call for me...my guess is it'll be a 1275 and Rivergate before I do the brakes, but they'll get done eventually.

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Brakes

Postby Darryl S » Thu Jul 15, 2004 10:34 pm

When I redid the brakes on Porky, I went to Advance Auto and bought 2 remanufacture calipers for $39.00 each. The only thing is they didn't have the left side so I got 2 right sides and when I bleed the left side I just unbolt it and flip it over but leave the pad so they squeeze the rotor. I just get the bleeder screw up high. Advance is showing the left side now but I don't know if they have them. When I start back working on my Bugeye, that's where I'll get my calipers. Take some old ones as cores and get rebuild ones. The rotors are cheaper from Moss but from Advance, you don't have to pay shipping.
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