I've had several Hope brakes over the years and whilst the downhills bike have changed many a time the xc bike has always had a set of E4s with pro levers. This have been faultless to say the least and have provided 8 years of awesomeness.

I have a set of redundant M4s with mini levers that aren't really worth selling so am contemplating changing the old pro levers for the mini levers. I have in the back of my mind though that the levers wouldn't be compatible due to master cylinder sizes etc. Is that the case?

I seem to remember from when they switched over to the mini lever they changed the piston size/volumes as the lever put outr a different amount of fluid and so weren't compatible.

I've still got a set of E4's lovely brakes, but very poorly now and a bit heavy, debating on whether to pay to resurrect them or not – new rotors/seals/hoses/pads…..

Thanks Andrew, I had the same in the back of my mind. Think there's a small difference between the calipers themselves anyway but wasn't sure. They are very reliable brakes but I wouldn't go to the lengths of buying new disks, seals and pads for the again. When these are done they will get retired… since they have done about 9 years of hard service

I was coming to the same conclusion, but they're classics, 9 years old too, my first discs as well!

Currently seeping fluid from the lever, which has as much vertical play as the distance it moves when you pull to put the brake on.

I love the E4. Still running two sets now. It's an experiment I've pondered about. The piston sized did change as E4 to M4 was when they changed from all 4 pistons being the same size to the leading edge pistons being different. Not designed to work together but I think it would be worth a try. Either you'll get better pad clearance and less power or more power and less pad clearance. Give it a go and let us know!

If anyone has redundant E4s, I'd love to get my hands on some more. Maybe with a number 5 calliper if possible!

Andrew – is your fluid seepage coming from the diapragm? Both my pairs leaked badly and I thought they're time had come. Turned out it was the diaphragm and my spares were slightly dirty and they still allowed some seepage. Bought some new ones and no problems since.

The levers will work fine whatever caliper they're pushing. There may be a small difference in the volume of oil being pushed around, but it makes very little difference to the performance. A friend of mine used to use a DH4 caliper on a Hayes HFX lever, and it still worked well.

I may have a caliper or two lying around, if anyone wants them. Certainly got a couple of caliper halves, and probably a rebuild kit or two. Replacing the lever seals is a pretty easy job, as long as you don't mind the fiddly circlips…

Davy, if you've got any E4 kit going begging, I'd be interested to hear more. I've got a googlemail account by the same name.

Cheers.