Caliper Seals

1982 XJ750 Maxim

Two questions:

1) Any way to tell if the caliper seal is bad. I have the piston out. I would love not to not buy a seal but really don't know how to examine it. If I need, I can post a picture.

2) I have found some caliper seal kits, http://www.z1enterprises.com/detail.aspx?ID=1365 , I don't know why they would have two seals. Doesn't the caliper only have one seal?

Thanks again everyone. You are life savers. I am getting smarter but it is a slow process.

 

Ones a dust cover for the seal and ones a seal..just like the forks , If im remembering correctly.

 

Does the dust cover fit over the top of the seal?

 

Jon...there will be two separate "grooves" or seal lands cut into the bore of the caliper body....the one "further down" into the caliper body is the wider groove, and it's for the FLUID seal....the one nearer the outer edge of the bore is thinner, and it's for the DUST seal.

The kits from Z1 and all others who advertise them as for "XJ750" models are only half right; those seals are for XJ750 SECA models, which also fit the XJ550 models (and the XJ1100 front calipers, too), and the problem with that seal kit is that the fluid seal is a bit thinner, front to back, than the seal that is used on the 650 Turbo/750 Maxim style caliper (the XJ550, XJ750 Seca, and XJ1100 models all use the same caliper body, while the XJ650 Turbo and XJ750 Maxim models share the same caliper body, but it is a completely different caliper than the XJ550/XJ750 seca/XJ1100 caliper body).

The thinner seal from the 750 Seca kit will tend to "walk" or roll around, laterally, in the groove as the piston expands and tries to contract, and in some situations, could cause piston seizure......not a good thing.

Many places take the manufacturers "word" that part XYZ fits what they say it does........research takes time, and costs money, so you can quickly understand where the incentives are.

Part of the confusion is that in the rest of the world, there was no XJ750 Maxim or Seca models; there was just a single model, called an XJ750, and these rest-of-the-world models are basically identical to what the North American market knows as the XJ750 Seca models (of course, the XJ750 models in the rest-of-the-world also came with a factory oil cooler......).

So the XJ750 Maxim and Midnight Maxim models are unique to the North American market, and when they were developed, Yamaha used the XJ650 Turbo brake calipers on them (a better design caliper, by the way, in my opinion). So when some manufacturer at a time long ago, and in a place far-away, decided to offer "XJ750" caliper rebuild kits (fluid and dust seals), what they had in mind and were "correctly" describing is the caliper seals kit for the rest-of-the-world XJ750 models.......which are basically identical (and use the same calipers as) the North American XJ750 Seca models.

Clear as mud yet?

 

Wow! This seams like it could be a problem when purchasing lots of different parts. I want Maxim - they think "Rest of world". That will stink. Glad I have been buying parts from you. I know YEARS have gone into you understanding all of this. Thanks for sharing.

 

OK, So I got the seals out and the top seal, the dust seal is a little iffy. The fluid seal seams OK. I will probably be ordering a rebuild kit. I know better safe that sorry; however ---

has anyone done this and left a dust seal in with a few nicks. Success, failure, etc.

 

Thought about it for about two days but ended up buying the factory kits when prudent thought reminded me who's can was on the line.

 

Yeah really. Your whole survival is dependent upon those two (or four) little rings of rubber. I would never even consider re-using or renstalling them once I've pulled them out-- they just get replaced.

Talk about false economy.

 

Since you already have them apart go ahead and replace them. The parts are inexpensive . You will have a good piece of mind knowing your breaks will work/

 

Alright, alright. Fine! I will purchase the new ones. Honestly I think the old ones would have worked OK; however, I could see them getting the tiniest leak and then slowly get all gunked up again. So I ordered them tonight.

I am trying to only do enought to make this bike safe, fun, and run well. I am afraid I have another 3-500 to put into her. She was in worse shape than I thought. Oh well. Enjoying working on her. Nice project.

Thanks everybody!

 

Understandable, but there are certain areas where cutting corners isn't the smart thing to do.

These are OLD bikes, stuff that hasn't been worn out is dried out, rotted or crumbling. Things will need to be replaced. A lot of things will only need to be replaced ONCE, and then you're good for a long time.

Be realistic about it, DON'T make cost-cutting decisions that affect safety, and take a few minutes to read this: http://xjbikes.com/Forums/viewtopic/t=14581.html

 

Thanks ... I hadn't thought about some of the things in the link you sent. I am really enjoying working on her. I am just going to have to suck it up and maybe stop working on it until my wife finds some more work. Such is life!

Thanks again!