TR6 Toyota Caliper Conversion

[glemon]

I am contemplating upgrading my brakes on the TR250, I have upgraded various other aspects of the car modestly, but have left the brakes stock (all parts new or rebuilt, rubber replaced, so safe and in fine fettle) other than ceramic pads. In looking at brake upgrades and the Toyota 4 pot conversion seems like the most bang for the buck.

I have read the benchmark article and testing on VTR and am impressed with the test results, but also a little confused. The article suggests you upgrade to bigger bore rear wheel cylinders which to my simple way of thinking and understanding of mechanical advantage would mean you would have greater rear braking force, or to put it another way more force/friction applied to the rear brakes for a given pedal effort.

This would seem to me to be counter improving overall braking, if the fronts are more efficient with the four pots wouldn't there be more weight transfer to the fronts on hard braking and more of a tendency for the rears to lock up?

Or do the Toyota four pots change the brake balance equation in other ways so that the bigger rear wheel cylinders simply restore that balance?

 

[tdskip]

Hi. I've done this on the TR4a and TR6 without issue. I used the uprated new rear cylinders on the TR6 (driven con brio) but used stock cylinders on the TR4a and the balance is fine on both so far. That said I haven't driven the TR4a aggressively so there may be imbalance issues I haven't found yet.

The conversion is as straightforward as written up, expect to trim the heat shields some and fabricate brake lines but that is about it.

 

[glemon]

Thanks, good to know, sounds like upgrading the fronts and maybe doing the rear wheel cylinders later would be OK. I have a local hydraulic shop who I am sure could make up my the needed lines, staffed by old timers, know what they are doing, reasonable rates.

 

[Marvin Gruber]

I have the same setup on my 56 TR3. Doesn't act any different, just stops better. I like having those bigger pads. Cheaper to replace the calipers as well.

Marv

 

[PatGalvin]

Ted (TSI) will make up custom flex brake lines at a reasonable price. My custom lines have standard threads on one end and metric on the other.

Pat

 

[Tybalt]

On the 7/8" rear wheel cylinders, the basic casting body is the same as the TR-6 cylinders so it is indeed a direct drop in substitution. Those 7/8" rear cylinders were used on just about every four wheeled Morgan and on the early Sunbeam Alpines. When I did mine, I wound up getting the wheel cylinders from Classic Sunbeam in Otego NY. The price it was much less than what anyone at a Morgan source wanted for them but it's been a while and things may have changed in that regard. I also made up my own lines since I had access to a tube shop. When we did this conversion on another TR, we had the lines made up at a local hydraulic supply. It didn't cost much more than doing it myself and all we had to do was hand over some money (such a deal). There's one of those 7/8" cylinders in there buried under that drum.

 

[glemon]

I got my Toyota calipers, I am in no rush to get things done so I am just tackling things a step at time. The toyota caliper bolt holes are 12mm, the bolt holes in the mounts on the car are 7/16" slightly smaller. The VTR article on the conversion recommends you use later TR6 bolts with the metric calipers, as they are a direct fit.

Unfortunately all sources I could find list these bolts at just under $10 each. I decided I would not pay over $40 with shipping for 4 stinking bolts. So I decided to make my own shims. After an unsuccessful attempt with an old license plate I went to the hardware store. The had some 15/32" od 7/16" id (.014" thick) brass tubing. Perfect on the bolts, still ever so slightly loose on the caliper, used some .005 sheet brass stock to make a shim, very useful stuff to have around for such purposes by the way, which is so thin you can cut it with a good scissors and the fit is snug, I made them ever so slightly proud of the caliper so when I torque the bolts down it should make a little lip tp hold it place, although it is pretty snug even without. So far so good.

 

[Tybalt]

When I did mine and the one on the other TR, those bolts for the 16M calipers didn't cost any where that much each but it didn't really matter as they were on what seemed like terminal backorder from all of the usual suspects. We wound up installing steel bushings and then using a piloted reamer on the bushings to fit the bolts used with the 16P calipers.

 

[cheseroo]

I've done a couple of the conversions (front and rear) and am happy with the results. AS a side note, not really a large enough sample to say for sure but the Toyota's seem much less prone to squeaking than the TR calipers. When I did mine, I used the stock flex lines. There is a short piece of hard line from the caliper to a caliper bracket. I bought a short piece of metric brake hard line, cut it in half and reflared one end with the TR SAE fittings. As to the TSI lines, super unhappy with that guy right now. All I can say is check his written quotes against what shows up on your credit card.

 

[glemon]

Rich, glad to hear it about the squeaking, I have ceramic pads on the car currently "which are supposed to virtually eliminate all squeaks" well they don't, after they get hot they chirp quite a bit on light brake applications, I was thinking about doing the Toyota conversion, then it sort of slipped of the radar screen, but the squeaky brakes sort of put it back on the priority list.

The method you describe for attaching the lines is the same one I plan to use, I bought the metric lines a couple nights ago, seems like the best solution, and years down the road of I need to replace the rubber lines I can still use stock.

 

[Marvin Gruber]

Plan to do the conversion on my 250. What do you ask for (metric hard line) and where would I get them? I have the flaring tool from past projects.

Marv

 

[Fat_Dog_Garage]

Plan to do the conversion on my 250. What do you ask for (metric hard line) and where would I get them? I have the flaring tool from past projects.

Marv

Take a caliper with you and fit it in the store.

 

[tdskip]

+1 - any local specialist should be able to make one that is a perfect fit on the spot.

 

[glemon]

10.0 x 1 metric flare fitting goes into the caliper, I was able to find some 8" lines with the appropriate flare and fitting on one end and an SAE fitting on the other end, unfortunately not the right SAE fitting (couldn't get than lucky, would have had to cut the tube shorter and reflare it anyway).

 

[cheseroo]

I carried a caliper into the store and matched the hard line that way. The hard line came with a fitting on each end so I measured against the TR hard lines, cut the metric line 2x so I had two metric hard lines of the same length, cut the SAE ends off the TR lines, slipped the SAE fittings on the other end of the metric lines and flared them. Then bent and installed. What I can't remember is if the flare is a single, double or bubble flare. You'll need to watch for that.

 

[Fat_Dog_Garage]

I carried a caliper into the store and matched the hard line that way. The hard line came with a fitting on each end so I measured against the TR hard lines, cut the metric line 2x so I had two metric hard lines of the same length, cut the SAE ends off the TR lines, slipped the SAE fittings on the other end of the metric lines and flared them. Then bent and installed. What I can't remember is if the flare is a single, double or bubble flare. You'll need to watch for that.

Memory says it's a double flare.

 

[bobh]

Has anyone put speed bleeders on their Toyota calipers? If so what is the thread size. Part number?

Thanks,
BOBH

 

[Fat_Dog_Garage]

Has anyone put speed bleeders on their Toyota calipers? If so what is the thread size. Part number?

Thanks,
BOBH

I put Speed Bleeders front and rear. The Toyota calipers took SB1010S and the rear wheel cylinders got SB3824HD. The HD means Harley-Davidson and I got them because the bleed nipple was a bit longer. Speed Bleeders are great.

 

[bobh]

Thanks Fat Dog!

 

[tdskip]

Bobh, report back on how these work out for you. My personal experience has been mixed, might just be me.