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Discussion Starter · #1 ·
hey guys whats up i have heard so much about this mod how do you do this and what material do i need to do this. will this mod affect the way my rear brakes grab when i am doing a burnout will it help or hurt me. pro's and con's to this if any.help!!!! :mad:
 
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Discussion Starter · #3 ·
so with this mod all you change is the bolt on the outside and the valve on the inside and eliminate the spring. is this all that it is. :confused:
 
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Discussion Starter · #4 ·
You remove the valve and the spring. But due to the hole in the front bolt being there for a vent to let that valve move you need a bolt without a hole. The rear bolt is the same bolt without the hole or the peg to put a rubber cap on. The stealth bolt is basically the same bolt as the original bolt but has no hole in the middle. I have even heard of people tapping the hole and putting a bolt in it but easier to use a new bolt in my mind.
 
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Discussion Starter · #5 ·
I would have to agree with Elixir on that one. I tried to drill and tap mine and through my own haste, I broke the tap. Anyway, after letting loose a string of obscenities that would make any boiler-mechanic sailors head explode, I ordered a stealth bolt from Dan at www.clearimageautomotive.com and when it arrived, I did the mod the next day. My brother volunteered to help me bleed the brake system and that was about all it took. Bleeding the system was very easy. After this, I took it for a drive and was surprised at how the car felt. It stops much sooner than it used to. Now all I need to do is wait for my Earl's brake lines and get some ATE Blue and I'm set.

Michael :cool:
 
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Discussion Starter · #6 ·
You got bit like many other folks have, including myself, in attempting to tap the bolt hole too quickly.

It can't be stresed enough: when you tap the bolt with the 6x32 tap, keep it well lubricated and TAKE YOUR TIME - cut an 1/8th of a turn and back off at least 3/4 of a turn and continue this until the hole is completely tapped. Backing off after each 1/8 turn cleans out the cuttings.

Also...make sure you enlarge the hole with the proper drill bit before tapping. For a 6x32 thread, a #36 drill bit will yield 75% of thread depth, a #33 drill bit will yield 60% of thread depth. I always use a #36 bit.

And don't feel bad, I've done many of these for people and about three bolts ago I too broke the tap. I blamed it on haste and beer; but haste was the cause. I salvage it by driving out the broken tap, redrilled and used a slightly larger bolt.

We all step in our messkits from time to time - it's called the School of Hard Knocks and the lesson was Murphy's Law.

Doug
 
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Discussion Starter · #7 ·
Tap the stock vented bolt as Doug Wood wrote above. He has the method down perfectly. I also seal the 6-32 screws threads with Loc-Tite 271 Red. Let it dry overnight. Then install as normal. This will prevent even the remotest possibility of a dangerous leak.
And bleed the ENTIRE brake system back to front! I have done four bolts in this fashion and they all work as prescribed. Including one friend's SS that auto-X's.
 
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Discussion Starter · #8 ·
Roger on what GForceSS said. I described the tapping procedure. He covered "the rest of the story"

Gang, this is a relatively easy mod to do provided you follow ALL the steps described in the above referenced link and take your time. Do it right the first time - if not you may not get the chance again.

This mod really is easy and yields excellent results. Remove and tap the vented bolt on Friday evening, let it sit overnight for the Loctite to set, reinstall it Saturday morning, then jack & support the car and bleed the brakes properly.

And...as always...if you have any questions, post this forum. It's been covered countless times before, but none of us want to see you error and someone will always provide you with guidance. It's what this board is all about. ;)
 
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Discussion Starter · #9 ·
Item:

If you mod the bolt on the combi valve closest to the radiator (on the rear brake hydraulic circuit), then you are doing the proportioning modification.

If you mod the bolt on the combi valve closest to the firewall (on the front brake hyd circuit), then you are doing the metering modification.

The proportioning mod removes the 90:10% front:rear proportioning needed on a civvy disc/drum car (because rear drums are self energizing once applied, so you only need a little bit of force to get them working). You need something more like 70:30% front:rear on a disc/disc car like the WX3/9C1.

The metering mod removes the delay in activating the front brakes. The metering was included by GM because the rear drums don't instantly apply until the brake shoe return springs have been stretched. You don't want the metering (delay) function once you fix the proportioning because in a hard stop, it means the front brakes WON'T come on at the same time as the rear brakes. In an easy stop, you won't ever notice the difference with or without the metering mod because the metering orifice has no effect.

BTW, the combi valve is called a combination valve because is serves the combination of three functions:

1. proportioning front to rear
2. metering the fronts
3. elec (shuttle) switch for the hydraulic failure for either the front OR the back brakes.

FYI. - Ken
 
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Discussion Starter · #10 ·
Man, I'm getting more and more confused as this thread goes on! I'm going to be doing this mod in the next month or two, and I've already got the stealth bolt, but now I have no idea what to do with it.

Kdrolt, are you saying I need two bolts? And I need to do both the proportioning mod and the metering mod? Or what...? I'm lost. :confused:
Ben
 
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Discussion Starter · #11 ·
<BLOCKQUOTE>quote:</font><HR>Originally posted by NemeSS:
Man, I'm getting more and more confused as this thread goes on! I'm going to be doing this mod in the next month or two, and I've already got the stealth bolt, but now I have no idea what to do with it.<HR></BLOCKQUOTE>

Detailed instruction on the proportioning mod are on the IGBA web site. ( http://www.b-body.net )

That should be enough direction for you to figure out what to do with the stealth bolt.

<BLOCKQUOTE>quote:</font><HR> Kdrolt, are you saying I need two bolts? And I need to do both the proportioning mod and the metering mod? Or what...? I'm lost. :confused:
Ben
<HR></BLOCKQUOTE>

No, you don't need two bolts. If you choose to do the metering mod, you can modify the existing firewall-side 19mm bolt yourself with a file.

I'll dig up what I once wrote on the metering mod and post it here. And the metering mod is a minor mod, it won't dramatically change the proportional braking like the proportioning mod does.

Note well that I posted the metering mod info once on several digests, but was reminded that you can lead a horse to water but you can't make him drink. - Ken
 
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Discussion Starter · #12 ·
Thanks for the followup Ken. And in my defense I'd like to point out that I'm still an Impala newbie! I've had my car for less than 6 months, so all these mods that are "old news" to you original owners are still new info for us newcomers. Some of us couldn't afford these cars when they first came out (I was going to school and earning 3 grand a year during the summers - hardly enough for a $25,000 car!!) but can now afford a used one and are still learning the tricks of the trade! Thanks for the help!
 
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