XJ Rear Caliper

[bikerphil]

Has anyone tried replacing the stock XJ rear caliper, the type with the goofy tapered pads, with one from a Standard? I would imagine the stopping power would be greater, the piston diameter is smaller on the Standard type caliper. This bike has the linked brake system, rear with the left front.

[cajun31]

The rear from any special other the 81 LH midnight special would give you the same rear brake. You would need a couple of parts.. including the rear master cylinder, rear caliper and associated brackets as well as the front joint. Of course you would also have to replace all of the hoses and might have to consider a larger front master cylinder to push two calipers rather then one. I wouldn't give up the two front calipers you already have because they basically are set up like the rear with the better pads in my opinion. They aren't tapered like on the other specials.

[bikerphil]

I am not trying to de-link the brake system.
I have the caliper mount bracket and the caliper with all the SS lines and fittings needed to replace the rubber lines. I'm not changing the rear master cylinder, just replacing the rear "Special" type caliper with a "Standard" type. My only worry is the smaller sized piston in the Standard caliper. Hopefully the proportioning valve will compensate for this somehow, maybe directing some of the pressure balance towards the left front caliper.

[cajun31]

I guess I took it for granted that you wanted to de link as most ask. Some of what I said still applies though. If you were to change out all of the brackets and caliper from a let's say 80 model special you would effectively get rid of the tapered pads. What you want doesn't require standard parts. As you know the XJ and LH used tapered pads like the front calipers on the 80 and 81 specials other then the LH.

[bikerphil]

Yep, the Standard and Special use the same rear caliper and mount bracket, you are right.

[cajun31]

I would think the rear master would handle either caliper the same and I wouldn't think that your stopping power would be any different. Bottom line is that these old one piston calipers are what they are. As you can see from my signature I have both an LH and an LG and really don't notice any difference between the two bikes when braking. Of course I am cognizant of the fact that on the LH when I hit the rear I am actually employing the front left at the same time. But then when I learned to ride and went through motorcycle safety courses they always taught us to apply both front and back brakes evenly when stopping. One of there tests was to line up on about a 65 yard straight away... goose the engine then apply both brakes hard to stop the bike. Watched many folks go into power slides riding their bikes down. In any case ... and it's just my opinion I don't think you will see any noticeable difference in that rear brake stock or changed.

[bikerphil]

Thanks Jim, I didn't think it would make too much difference in stopping power between the two types of calipers. I just think the normal type caliper is a better design and I have a newly painted and rebuilt one ready to install.

[bikerphil]

My other real concern with this mod is, the back brake locking up too easily and skidding out with an abrupt emergency stop.

[cajun31]

I don't believe that is going to be a problem either way. Jamming the rear brake on the linked system employs the front left too. That was one of the main reasons when I restored the LH that I left the brakes linked. On emergency stops, at least for me I have the reaction to hit the rear first ... maybe the way my brain works ... who knows, but that is what I do and then I grab the fronts. milliseconds in reality but I guess could result in a rear slide. Again why I rather like the linked brake system. Good luck on which ever you choose to do. Ride safe and keep the wind at your back.

[bikerphil]

Thanks Jim, I'm being extra cautious with this swap because the bike belongs to a friend, I really won't be riding the bike that much to keep an eye on it's behavior.