Hope Tech 4 inconsistent bite point

[Daan]

Wondered if any of the Tech 4 user's here recognize this?

Basically, squeezing the lever a few times in succession makes the bite point come out a good centimeter. When you look at the caliper, the pistons retract quite slowly. It's very annoying. Both front and rear have it, front slightly less bad. Brakes are basically brand new (and have been leaking past the caliper pistons a bit too much too, but that's another story).

[craigjames]

Mine have been similar, sometimes feel solid and nice, other times they'll put nearly to the bar. Initially i thought it was the bleed, but i've had several people bleed it including myself and no change.  I then noticed that my poorly manufactured frame had a slightly misaligned caliper mount; I physically can't mount the caliper parallel to the disc rotor. I was considering a new frame, with the hope the mount wouldn't allow the brake to be perfectly aligned. But this makes me think the brake could be the issue! 

Edited April 17, 2023 by craigjames

[AdamR28]

Have you tried the same tests on other (open system) disc brakes? I have a feeling you might find exactly the same thing happens.

[Daan]

@AdamR28Yeah I guess some pump-up is to be expected. But, have tested this on a Hayes Dominion A2, which didn't seem to pump up at all, and on a Hope Tech 3 V4, which did pump up a bit, but not nearly as much as this one, plus you really had to be much faster with flicking the lever for it to happen. You actually notice this on the T4 while doing back wheel hop stuff.

@craigjames think that's a different issue, but could perhaps be this: https://vstatic.mtb-news.de/videos/2/8/4/4/5/1/_/video/487c190_154482_trim.ADF023FE-864D-4895-BA38-346EBBF6A4EA.m4v

Has to do with a faultily sized lever piston/body combo due to an error with one of the CNC machines. Don't know why they didn't do a recall of the affected brakes, as there were quite a few. Had the same problem on mine, had to go back to Hope for them to fix it.

Edited April 16, 2023 by Daan

[Mark W]

20 hours ago, Daan said:

Has to do with a faultily sized lever piston/body combo due to an error with one of the CNC machines. Don't know why they didn't do a recall of the affected brakes, as there were quite a few. Had the same problem on mine, had to go back to Hope for them to fix it.

Experience teaches that you can generally take Hope's 'reasons' for problems with a pinch of salt. e.g. with the Pro 4 they said there was a faulty batch of pawls that might have affected around 30 hubs, but that clearly wasn't the case as there are plenty of reports out there of people exploding some of their pawls, and the pawls themselves had a re-design. There have been other things like that in the past too, but more specifically with the Tech 4 there have been people getting leaking brakes straight out of the box which was due to a few different reasons according to Hope. I have a friend who's had two brakes (the initial one then the warranty replacement) leak from the lever for seemingly no reason. You can also find similar chat in the comments here.

That said, wondering bite point isn't unique to Hope - Shimano are notorious for it, and I've found my Maguras can be too if they're not set up perfectly. As soon as the caliper is a little bit misaligned they develop that same feeling almost immediately.

[Daan]

Always a good idea to let your customers test your products. Since they were also micro leaking at the caliper piston end, I've thrown on some Shiguras to do some more product testing. No wandering bite point at all, and that for a Shimano.

Also, even on a bleed block, the T4 bite point consistently keeps coming out. It is consistent, in that it always does so by the same amount. Don't know if it's normal for the T4, or if my set is from the beta batch in this regard too, but the difference between initial bite point and bite point after repeated application is too large in my book.