Commando TLS problem

I have a 1962 Dominator 99 which has a Commando TLS front brake fitted which has great stopping power compared to the original SLS. My problem is that when it rains the front brakes turn into a sponge and are worse than useless. There is an air scoop at the front with three vent holes at the bottom of the drum. The shoes have only about 1000 miles on them and as I said work fine in the dry. I sealed off the front scoop but it made no difference and I can't see how any great amount of water could enter through the bottom vents. Has anybody come across this problem with the Commando setup?.

TIA
Peter

I think it's a common problem with all drum brakes

I have owned many bikes with drum brakes & never had that problem. pecon has a problem. I don't know the Norton drum brake though. Maybe the rain is running along the back plate & pulling itself into the vents?

Could it be the wrong lining material?

Jean

New linings are softer than stock(and so more absorbent) but just a bit of heat would normally clear a wet slip condition. So if you found your brakes wet you simply gently ride them a bit till you steam them dry. Once they are hot they will attract the wet in. More gently riding the brake in the rain. Somewhat par for the course with a drum brake but the condition should be easily cleared. A stock drive chain can be destroyed in one long ride in the rain if it is at temperature when it starts to rain. The heat in the chain will draw water right in. I have had Trans oil get milky in a soaking rain after the bike is at temp. I always check this after a run this happens on the seal is made to keep oil in not rain out.

I know this problem all to well. I have been told the cause is the front face of the air scoop collects water which is then forced by air pressure into the gap between the drum and brakeplate. Apparantly the cure is to cut the air scoop off completely and weld up the hole. I have not actually tried this mysef. I took the easy route to good stopping and changed to a disk.

Guys

Thanks for all the replies and suggestions

Pelican
Unfortunately I'm old enough to remember drum brakes on cars and I remember that when you hit a flood with them the brakes went until they could be dried out. Doing this with my brakes while riding in the rain has no effect, the brakes won't work again until the rain stops and the drum dries out completely.

Jeandr and Norbsa48503

Your suggestion about inferior quality shoes may be part of the problem. The TLS with new shoes were fitted when I bought the bike earlier in the year so I have no idea who made them.

Flo and Rustynuts

This is my main problem, trying to find out how the water is entering in the first place. I've already tried sealing the front air scoop but the problem remains, I guess my next step is to try to seal the rear vents but I honestly can't see how water could enter through here. I'm stumped..!!. I'm new to this site but if I can figure out how to post a photo I will be able to show my setup.

Jeandr said:

Could it be the wrong lining material?

Jean

Click to expand...

you could try these shoes - good stuff - and not to $$

http://www.vintagebrake.com/shoes.htm

Perhaps the drum has been turned too many times and has reached the end of it's life. Are the shoes (Linings) turned to match the drum radius?