TheSamba.com :: View topic - New wheels spacers now brakes soft and pulsing

Sat Aug 06, 2016 10:00 pm

Hey folks,
Added spacers, studs and love the feel of 16" rims -- thanks T3!

But -- now I have a pulse braking and the pedal is soft. I'll bleed tomorrow after work. But why would the drums or rotors have a pulse now? Strange that the would need a bleed too, no?

Anyhow, I was told that the drum orientation must be the same and I checked and they are -- the bolt holes are lined up even though there are no bolts. Perhaps I should put the bolts back in -- I can see the holes as the rims don't touch them.

Thoughts? Hope i don't need to buy new drums or get them cut. I did remove the rotors as well and repacked the bearings. As an aside -- the rear bearings looked like sealed units. Is this possible?

Thanks!

Sat Aug 06, 2016 10:54 pm

So you put different rims and tires on? Just clarifying but I assume so. The rims could be bent, or the tires could have a wear issue - either of which could cause the pulsing. If the overall diameter is say 10% larger then your braking power just dropped by 10%, which could cause you as a driver to consider the brakes "soft".

With no further info on tires/rims just speculating. I'd also double check that the rims are fully seated, and I assume you know about the little bolt on the drums that makes wheels sit crooked if it interferes.

Sun Aug 07, 2016 6:40 am

When you have a pulsation in the pedal, it's from either an out of round drum or a rotor that has uneven pad material deposits or is "warped". When you have those issues, the wheel cylinder pistons (drum brakes) or caliper pistons (disk brakes) are forced into contracting more than normal. This creates more distance between the shoes and the drum (drum brakes) or pads and rotor (disk brakes). To make up that increased distance, the pedal has to travel further. That most likely explains your "soft" pedal. I would describe as more of a "long" pedal though.

As for the cause of pulsation, I focused on your rear drums in our emails since your mechanic called me with some questionable questions about the spacers. However, the pulsation could be coming from the front or rear. Like I mentioned in the email, you really should have the drums checked for being round, but you would also have the front disks checked for uneven pad material deposition or "warping". Other than a bent or warped hub (from being damaged during stud installation, lugs tightened improperly, etc), that pretty much all that can cause the brake pedal to pulse.

Sun Aug 07, 2016 6:41 am

Lug nuts that aren't properly torqued, or over torqued, can cause pulsing.

Sun Aug 07, 2016 7:30 am

Thanks Christopher and all --

The wheels roll smoothly and the 'long' pedal is a good description. I'm a bit baffled as to how drum/rotors go out of round without the prerequisite of heat, but from removal as in the past they and on all of my cars have had inspections with removal and no issues of out of round afterwards. Anyhow, they'll get measured and cut if needed. In the meantime i'd like to get the pedal back 'up.'

The folks who did the swap cannot get me in until next week an I have a trip planned before then. They were torques to spec and rechecked 20 miles later.

I hope or wonder that bleeding this after noon will restore the pedal to a higher engagement point. The only way to measure the drums and rotors our of round is to get them in to a shop.

Will the bleed this aft and hopefully it will rise. A little pulse I can live with until it gets in. Low pedal is not reassuring.

Christopher at T3 get the highest of marks for product, email responses and a great attitude! Just was looking for advice for the bleed and any other thoughts about the pulsing when braking which came after the swap.

Sun Aug 07, 2016 8:11 am

Quote: I hope or wonder that bleeding this after noon will restore the pedal to a higher engagement point.

You can try bleeding the system because obviously if there is any air in there, the braking will only get better. However, the long pedal situation will most likely remain (at least to a degree) as long as the pedal pulsation remains. This is because each time the drum and/or rotor rotates, the pistons are pushed back into the wheel cylinder and/or caliper. The pistons are pushed back out each time you press the pedal, but once you release the pedal, they are pushed back into the wheel cylinder and/or caliper. In other words, while the van is moving, every time to you release the brake pedal, you are right back to square one with the pistons being pushed too far into the cylinder or caliper.

Sun Aug 07, 2016 11:16 am

Sounds like coincidence. Front studs thread in to the hubs just like the bolts. As long as the wheels and spacers are seated in the front and nothing else changed on the front time to concentrate on the rear.

The longer rear studs would have needed to be pressed in from behind. The shop would have had the drums off, possibly the rear shoes and depending on the length of the studs could have removed the rear hubs as well. It is more likely the rears were not assembled properly or worse, the hub was bent pressing old studs out and new ones in. That again would not be a result of the longer studs and spacers.

In my experience, a good brake pedal feel in a vanagon is the result often of properly fitted and adjusted rear brake shoes.

Probably should run the adjusters up so you can take your trip. Let the installer deal with it when you return.

Sun Aug 07, 2016 1:29 pm

Isn't the best way to run the adjusters to press hard on the brakes a few times?

Sun Aug 07, 2016 2:24 pm

oceanair wrote: Isn't the best way to run the adjusters to press hard on the brakes a few times?

In reverse.

Mon Aug 08, 2016 9:27 am

jimf909 wrote: oceanair wrote: Isn't the best way to run the adjusters to press hard on the brakes a few times?

In reverse.

...while driving backwards. But it only works if your adjusters are in good working condition.

Mon Aug 08, 2016 3:53 pm

Just went through this myself with a new set of the GoWesty HD brake drums that were significantly out of round from the factory. Caused scary amounts of pedal pulsation and a soft brake pedal. If you are getting a pulsating pedal but no steering shimmy under braking, then your pedal pulse is due to either out of round drums or the drums being slightly off-center on the rear hub(s) when mounted. This can be further verified by stopping the van from a decent speed (>30mph) using only the emergency brake. You may feel a slight pulsing in the e-brake handle.

If your rear drums are the problem here is what I would recommend:
1. Loosen wheel lug nuts.
2. Lift rear of vehicle safely onto jack stands.
3. Dis-engage emergency brake.
4. Remove wheels and brake drums.
5. Take your drums to a brake shop and ask them to check them for roundness. You need to know if your drums are out of round before chasing down other issues.
6. Inspect the hubs.
6.a. Make sure your hubs turn freely but don't have any side to side play. check for play throughout the hub's 360° of rotation.
6.b. Look for accumulated dirt, rust, metal shavings, etc around the mating surface between the hub and the drum. Look at both the flat surface of the hub around the wheel studs and the circular surface of the hub which the drums slide over. Also look at the corresponding surfaces of the brake drum. Remove any rust and/or foreign materials on these surfaces with a wire brush, steel wool or abrasive pad.
6.c. Inspect the new longer wheel studs that were pressed into the hub to make sure they were all pressed in completely and the stud lips are sitting flat against the back of the hub plate.
7. Assuming your drums are now verified round (or you've bought new drums and brake shoes), re-mount the drum onto your cleaned and anti-seize prepped hubs pushing them all the way onto the hub and then use the side of your fist to really seat the drum fully onto the hub.
8. Re-mount the wheel spacers and wheels.
9. Tighten the lug nuts evenly and progressively with wheels off the ground.
10. Drop the vehicle and fully tighten the lug nuts using the torque spec. recommended by T3 for your application.

My suspicion, as was the case for myself, is that your old rear drums have been out of round for some time but your rear brake shoes were also out of adjustment to the point that they were never actually coming into contact with your drums with a single press of the brake pedal. When your mechanic pressed in the longer wheel studs they might have also adjusted your rear brakes so you are now feeling your bad drums for the first time.

I should note here that unless you are running the ATE brand hydraulic wheel cylinders then your rear brakes will never function properly because the non-ATE brand wheel cylinders don't have the mechanical return springs which keeps the rear brake shoes positioned properly within the drum radius. Without the mechanical return springs the shoes fall out of adjustment quickly as they wear and require pumping the brake pedal to get the rear shoes to make contact with the drum.

EDIT: GW sent a replacement set of HD drums free of charge which solved my problem.

Mon Aug 08, 2016 5:17 pm

Wow -- thank you for that excellent and long post -- I really appreciate the effort!
I'll be checking for round and other issues on Thursday and will report back with any other information that others can use later.

Edit: just looked at my receipts and I do have ATE cylinders -- glad that is checked off the list.

Thanks again for the effort!