Fleeting thought here, has anyone built/produced a brace for the humongous protrusion that is the mastercylinder/booster combo? I know this thing flexes like crazy when I punch the stop pedal.

 

Mine does also... I figured it was just the T56 master cyl mod that weakened the firewall.

I've seen one but it was a custom built job, I think I may have something done up for me at some point.

 

i thought i had the pic, but there were a few here of braces mounted to a STB, using a bolt to slightly preload the end of the master.

 

Interesting. I'd definitely like to see a picture of what someone else has come up with...

 

hey, i found them.




my thought was to make a brace ot attach tot he 2 studs from the booster to the master, but i have not be able to work on a STB for my car yet and have not looked into clearance and such.

 

so what does this mod actually do.... im kinda interested...

 

My goal for it would be stop the MC from flexing upward so much and hopefully prevent any firewall cracking issue.

 

Thanks! I had the same idea as you and had planned to use the MC mounting bolts.

 

what can i say, great minds think alike

if you start work on this, im very interested to see what you come up with. I would start, but im not done with the headlight project, and there are clearance issues with the v6 thats giving me troubles with a STB.

 

Oh man this is a great idea. I did some googling and it seems like these things are very effective on many kinds of cars. Despite all my brake work, I still have the classic chevy soft brake pedal. Maybe this will help.

 

alright then, the race is on! Sombody do something quick!

 

I went out and goofed around with the car for a while. First of all, I could see the master moving from the drivers seat. It seems to mostly be moving up. I will need to grab my roomate later to see if its moving forward as well. I think we really need to control the upward motion along with the forward motion.

Finally, I just grabbed the master and tried moving it with my hand. It moves all over the place in any direction. It moves probably close to 1/4" Yes all the bolts are tight. I am highly encouraged that containing all this motion will be noticeable.

 

Well if you come up with something soon, make two and I'll help you test.

 

Well I got my roomates help and we measured 0.11" deflection in the direction parrelel to the master. I will be finding a way to reduce this. I have the UMI STB so I will probably be doing something similar to the pictures above.

 

Since I've never heard mention of cracking in that area in my years on TGO, reinforcement would "seem" to be unnecessary and/or overkill. That said, I'd like to hear more about why this mod would be a significant improvement over OE.

JamesC

 

I am not necessarily concerned about cracking for the reasons you brought up. I am interested in reducing the deflection in the hopes that it will make the brake pedal feel better. Other car communities have reported a firmer pedal with this mod.

 

i have seen/heard more of the clutch master causing tears in the firewall than the booster, but still, its only mounted to sheetmetal, and reduction in deflection will help prevent possible fatigue of the firewall.

 

I mocked up my bracket for the UMI STB. It will be made of 1/4" steel and be welded to the bottom of the STB. Depending how it turns out, I may add some bracing.

 

If you can direct me to anything useful (without a ton of effort), I'd like to school myself a bit. Just never heard of any issues in this regard.

JamesC

 

Sure, these are the posts I came across in my research. The S2000 guys measured 6mm of deflection IIRC .

S2000
http://www.s2ki.com/s2000/topic/8614...ylinder-brace/

Subaru
http://www.subaruforester.org/vbulle...stalled-30247/

350Z
http://my350z.com/forum/brakes-and-s...lled-pics.html

 

Crap. I guess one more reason to finally order a STB.

 

What kind of work/modification has to be done to the master to use the bolt? BTW, it would appear that the Edelbrock 3-point for TBI (and some carb) applications would be more problematic.

JamesC

 

No modification to the master. The bolt merely pushes against the snout of the master. I will have a swivel levelling foot on the end of my bolt to distribute the load.

 

i had thought that a grade8 carriage bolt would be best, since it has a smooth rounded head, but thats provided you can find a grade 8 carriage bolt. that swizzle one should work though

as for the tab on the STB, i would think a gusseted piece of 1/8" steel would be more than strong enough, and lighter than the 1/4". but i dont really know what kind of force will even be applied to the bolt.

 

Yeah its working load is 3800lbs compression. I should be good. I also wanted to make sure my brace can slide on the snout of the master if it had to. So in a turn, my brace won't induce a side load on the master.

Agreed, gusseted 1/8" would be fine. I'm not a welder, so I'm trying to keep simplicity so my welder can't screw it up. Haha. It also makes my fabrication easier. The load should be pretty high though.

I will be curious to see how the STB likes the bending load.

 

Here is what I have so far. Need to make one more gusset obviously, and some finishing work. I ended up using 3/16"

 

that looks pretty snazzy.

 

You should fab a few of those up to sale. I don't have the metal work experience you do.

 

Thanks for the compliment. It is all done with a drill press, hack saw, and bench grinder. At the rate these are taking, I would have to charge way to much money to start selling these.

Need to find someone with proper machine tools to reproduce them. They would look a lot nicer too.

 

Made some progress. Got everything welded up. Will be testing tomorrow.

 

 

welds look nice, did the bar warp at all?

 

Clever.

JamesC

 

Yes I am a sucker for a good tig weld. I would love to learn some time. The bar fits back in the mounts with no adjustments, so if the bar warped, its very very little. I cannot notice any.

 

where did you get the swivel foot? i kinda like it

 

http://www.mcmaster.com/#6103k129/=dpc8ps

 

thats what i figured, but i was unsure about the grade 5 bolt, not i see its a seperate piece, and you can just buy the foot

thanks

 

That looks amazing. Good job.

 

Yeah they offer it with both an integrated stud and without. I bought one of each. The pictures above are without the stud. I ended up using the one with the stud, as its much easier to adjust. Then I added a jam nut to lock it in place and an acorn nut on the other side for decoration. See pictures below.

Parts List: All part numbers are from McMaster-Carr.

2" wide, 3/16" thick mild steel
6111K223 - level mount with stud, 3/8-16, black
98797A031 - 3/8-16 nuts, 5 pack, black
91434A155 - 3/8 washers, 10 pack, black
98667A250 - 3/8-16 acorn nut, black

If you want to use the base without the stud, substitute 6111K223 with:
6103K129 - level mount, 3/8-16
&
94967A577 - 3/8-16 screws, 5 pack, black

Now, more pictures. This is the current configuration.

 

And installed. I used the adjuster to put a 1/16" of preload on the snout of the master. We'll see how that works out.

 

Well I went for a short drive. There is a pretty mild improvement to the pedal feel under light to moderate braking. I have not tried heavy braking yet.

I did notice that the clutch is lighter, I guess the clutch master flexed the firewall too.

So I do need to do some back to back testing. As well as flex testing with my roomate. Overall not quite the effect i was hoping for. I'm still chasing the pedal feel of my Acura.

 

Did some more goofing around today. Found that the whole STB is flexing. Even though the MC brace is near the strut mount, the bar itself is flexing. Hence why I did not see much improvement. I will need to find another way to brace this area. Bummer that it didn't work. But I'm glad there is still hope for this mod if properly braced.

 

How/Where is the STB flexing? The sheetmetal it mounted to doing the flexing? The rod ends doing the flexing?

 

Like I said. The bar itself is flexing. The UMI STB uses a 1.25" OD bar.

 

Add 2 down tubes from the STB to brace it to the subframe to prevent upwards flex. Add 2 rearward bars from the STB to the firewall to prevent forward flex.

 

the bar is flexing??? wow, thats impressive. must be a lot more force there than i would have thought.

hmmmmm, will have to rethink my idea here.

 

Yeah, crazy huh?

I'm going to look and see where I can add some bracing without being to heavy. I think a bar from the core support to the STB would be good.

 

Just curious, any updates on this?

 

Not much from me. Brace is still there. I still have the STB flex. And I never did anything to try to reduce it. IMO its a good mod if you have a STB sitting there anyway.

 

run a brace from the outside master cylinder mounting bolt forward to where the strut tower brace bolts to the top of the strut.