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Spongy pedal with Wilwood Dynalites
Hi guys,
I got a pair of new Wilwood Dynalites last year, and despite bleeding them until I'm blue in the face, they still feel terrible and wooden. Absolute brake power is ok though. The car still stops well, but the pedal is a million miles from feeling good. I've tried the method where a helper pumps the brakes and I open and close the bleed nipples, as well as gravity bleeding them. The calipers have 4 bleed nipples, and I'm bleeding the 2 ones at the top of each caliper. I've also noticed the nipples seem to weep fluid. Has anyone had any similar issues bleeding 4 pot calipers? Or have you had more success with different methods of bleeding? I'm considering buying a kit where you pump fluid into the caliper, which should force air bubbles out the resevoir. When I'm bleeding the calipers I think I've got all the bubbles out, but when I hit the calipers with a rubber mallet, more bubbles ALWAYS appear. I've tightened the nipples as much as I dare. All in all, I'm pretty dissapointed with the purchase so far, and have considered returning to 'sport' mx5 brakes because of the problems bleeding them. I've also thought about replacing all the nipples with new ones, but don't want to waste my time. The nipples were brand new after all and I still have issues. Finally - all the hoses are brand new braided lines from HEL with new crush washers. |
Did you try bench bleeding your master brake cylinder? If the master cylinder had air in it at any time, you need to bench bleed it....
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you using any kind of thread sealant where the hoses screw into the back of the caliper? It's a tapered pipe fitting if I recall and it needs teflon tape or something.
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Originally Posted by y8s
(Post 862839)
you using any kind of thread sealant where the hoses screw into the back of the caliper? It's a tapered pipe fitting if I recall and it needs teflon tape or something.
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IN THIS ORDER:
-Remove the master cylinder from the car and bench-bleed it, then reinstall -Hook up a pressure bleeder and bleed the LEFT REAR caliper. Bleed until you hit 0.25L of fluid, or until the bubbles stop, whichever happens last. -Bleed the RIGHT REAR caliper. Bleed until the bubbles stop. -Bleed the two front calipers (left/right or right/left, doesn't matter). Start with the inside bleeder, bleed until there are no bubbles, then go to the outside bleeder. -Feel the pedal. It should be firm right from the top, with just enough deadplay to ensure that the brakes aren't dragging. -If the pedal feels OK but not great, bleed LR, RR, RF, LF, in that order. Run ~0.1L through each caliper. If you still have a spongy pedal after all of that: -Pump up the brakes to build pressure, then stand on them as hard as you can for 20 seconds. -Check for leaks in this order: all 4 bleeder screws on both front calipers, front caliper-line adapter, front brake lines (crimps and fittings), all OEM line connections to the master cylinder and prop valve, rear junction fitting (RR fenderwell), rear brake lines, rear banjo bolts/washers If there are no leaks: -Jack the right side of the car up as high as you can, then bleed the LR, RR, RF calipers in that order. |
Originally Posted by Savington
(Post 862841)
...really useful stuff...
Props |
Originally Posted by GrahamC
(Post 862840)
That's pretty interesting to hear. I didn't use anything, and of course there are no washers on the Wilwoods. It certainly sounds plausible, and borderline exciting if that would fix my problem. Anyone else had this issue?
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I can't tell from your sig, but do you have ABS? If so, check out this thread.
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Savington's post (as always) is excellent advice. But I have a few additional points.
When bleeding these wilwood calipers, compress the pistons fully first, and don't build pressure in the caliper you are bleeding. Make sure the pistons stay fully back in the calipers while bleeding that corner. You shouldn't need to do this every time you bleed, but it has helped me to resolve a similar issue on Wilwood 6-piston calipers in the past. If you ever boil the fluid, its a good idea to do this method as well. This method can be used on pretty much any type of caliper, though it can be a pain on rear calipers with integral parking brake mechanisms... Also, I've had issues in the past with the 6-piston (SLR-6 I think) wilwoods where the aluminum was soft, maybe from overheating, I'm still not sure, but the calipers themselves would flex significantly when pressure was applied, creating a soft pedal. The only solution in this case for me was to replace the calipers. Fwiw, my experience with these calipers was on Mustang race cars, so its not exactly the same, but similar enough to help. They were basically the US equivalent of the FIA GT4 series cars at the time. We switched to brembos around 2005 and have run them ever since. |
sticky?
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Originally Posted by Savington
(Post 862841)
IN THIS ORDER:
-Remove the master cylinder from the car and bench-bleed it, then reinstall -Hook up a pressure bleeder and bleed the LEFT REAR caliper. Bleed until you hit 0.25L of fluid, or until the bubbles stop, whichever happens last. -Bleed the RIGHT REAR caliper. Bleed until the bubbles stop. -Bleed the two front calipers (left/right or right/left, doesn't matter). Start with the inside bleeder, bleed until there are no bubbles, then go to the outside bleeder. -Feel the pedal. It should be firm right from the top, with just enough deadplay to ensure that the brakes aren't dragging. -If the pedal feels OK but not great, bleed LR, RR, RF, LF, in that order. Run ~0.1L through each caliper. If you still have a spongy pedal after all of that: -Pump up the brakes to build pressure, then stand on them as hard as you can for 20 seconds. -Check for leaks in this order: all 4 bleeder screws on both front calipers, front caliper-line adapter, front brake lines (crimps and fittings), all OEM line connections to the master cylinder and prop valve, rear junction fitting (RR fenderwell), rear brake lines, rear banjo bolts/washers If there are no leaks: -Jack the right side of the car up as high as you can, then bleed the LR, RR, RF calipers in that order.
Air clings to crevices, the hammer helps break them free. |
Originally Posted by hustler
(Post 863777)
I start with a reverse bleed from the right rear, then bleed the left rear via reverse bleeding the right. Does that make sense?
You always always always bleed LR, then RR. Drawing/pushing fluid into the LR from the main rear line will put bubbles in the RR line, which must be bled afterwards. |
anxiously awaiting results of sealing the threads on the back of the caliper.
all this bleeding talk makes me feel like giving a transusion to a man with open wounds. |
Motive Power bleeder. they are awesome. and fairly cheap.
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It's interesting how this issue pops up now and then. Personally, having installed 3 sets of Wilwoods on two of my Miatas and a friends ITR I've never had a problem with bleeding and poor pedal feel. I always bleed PR,DR,PF,DF and cycle 2 times or so.
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I won't be able to get to the car and try this for a couple of weeks, which is a shame but I'll update the thread just as soon as i've tried the above.
Remember on UK and Jap cars the master cylinder is on the other side (UK & Jap Driver side), or US passenger side. |
This doesn't change the fact that you should bleed the LR first, then the RR caliper. Then work towards the MC, not sure about the routing from the RHD cars.
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Originally Posted by GrahamC
(Post 862830)
Hi guys,
I got a pair of new Wilwood Dynalites last year, and despite bleeding them until I'm blue in the face, they still feel terrible and wooden. Absolute brake power is ok though. The car still stops well, but the pedal is a million miles from feeling good. I've tried the method where a helper pumps the brakes and I open and close the bleed nipples, as well as gravity bleeding them. So what what happened to ths? Im having same problem The calipers have 4 bleed nipples, and I'm bleeding the 2 ones at the top of each caliper. I've also noticed the nipples seem to weep fluid. Has anyone had any similar issues bleeding 4 pot calipers? Or have you had more success with different methods of bleeding? I'm considering buying a kit where you pump fluid into the caliper, which should force air bubbles out the resevoir. When I'm bleeding the calipers I think I've got all the bubbles out, but when I hit the calipers with a rubber mallet, more bubbles ALWAYS appear. I've tightened the nipples as much as I dare. All in all, I'm pretty dissapointed with the purchase so far, and have considered returning to 'sport' mx5 brakes because of the problems bleeding them. I've also thought about replacing all the nipples with new ones, but don't want to waste my time. The nipples were brand new after all and I still have issues. Finally - all the hoses are brand new braided lines from HEL with new crush washers. |
4 year old thread, user has been active once since 2012...who knows. I would follow what everyone else said. On mine we had to bleed them for a while, we gravity bled them first to try to get as much of the air out as possible since the entire system was bone dry. Basically just open the nipple but don't pump at all, leave it like this for a while, do in same order you would bleed. Once you see fluid close it and move to the next one, then go about bleeding process after all that is done. Took a while and check all the nipples for seepage, I know two of mine had some which will give you a pedal that softens, same thing as if your master was junk. Pedal will slowly go to the floor.
Sometimes it takes a while to get systems fully bled, especially when things are missed, check all connections and then check them again. |
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