HOW TO DO AN ADVANCED SEARCH.

Mon Jul 08, 2013 3:56 pm by Admin


For the benefit of 944Hybrids users there are two search functions available for you to use.
The purpose of this sticky is to explain the "Advanced Search" function because it is much more powerful and is the best choice when researching information.

When you log on to the site a list of options is shown in a line at the top of the page. One option is labelled "Search", use this option (NOT the search box lower down on the right).

After you click on the upper search option, a drop down box appears. At the bottom of this box is a radio button marked "Advanced …

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Problem with Dual Remote Vacuum Boosters

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Problem with Dual Remote Vacuum Boosters

Post  johntorg on Thu Dec 14, 2017 8:10 am

I just bought an 85.5 944 with a modified LS1 engine,  It makes 384WHP.  It has dual remote boosters similar to these Remote Booster This will be a track car and occasional daily driver.  The brake pedal is very low and spongy.  I would like to fix this before I take it to the track.  

It has been bled by the PO, but I will try to bleed it again.  The car has Turbo S big brakes in the front and stock turbo brakes int he rear.  It uses a stock 944 Master Cylinder feeding the dual remote boosters.  I have driven hybrids with no power brakes and prefer some kind booster.  I would also like to get this setup working if possible.  I know I can install a Hydroboost but would like to avoid the work and expense involved.

Does anyone know if the stock 944 Master Cylinder is up to the task?

I there a larger MC that will bolt up?

Has anyone installed dual boosters sucessfully?







johntorg
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Re: Problem with Dual Remote Vacuum Boosters

Post  sharkey on Thu Dec 14, 2017 1:49 pm

with those systems there is so much that could cause issues. it could have air in the system, id bleed the entire system first. it could also have the wrong sized master cylinders, or could be the wrong sized booster for what its doing.

i looked into these systems when building my car as hydroboost wasnt a viable option. the remote booster just seemed like a huge hassle and a tough thing to get working correctly. i ended up working through a manual system with a dual master cylinder setup, and once i got it set up right, it stops quite well.

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Re: Problem with Dual Remote Vacuum Boosters

Post  johntorg on Thu Dec 14, 2017 5:47 pm

Thanks for your input.  I build 944 Race cars for my own use and have a dual MC setup that i was planning on putting in a 944 Turbo Race car.  If all else fails, I may go in that direction.  I have driven a manual brake LS3 powered 944 on the track and found that it required so much foot pressure that it was hard to modulate the brakes.  I do have a Mustang Hydroboost that may be a better alternative for me.

In the meantime, I'll try to sort out the dual booster setup.  I also own an LS3 powered 924 widebody street car with Hydroboost, which works fine.  See Below:
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Re: Problem with Dual Remote Vacuum Boosters

Post  Arthropraxis on Thu Dec 14, 2017 7:10 pm

That is a common issue that I found when researching brake options. The big red calipers don't work well with the stock turbo MC and proportioning valve or it could be something in the system. Have you gone on Rennlist and searched? Cool setup with the remote vacuum booster.
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Re: Problem with Dual Remote Vacuum Boosters

Post  johntorg on Fri Dec 15, 2017 8:19 am

Thanks, I have been using Turbo S brakes with stock Porsche master cylinders in two race cars with no problems.  Everthing is pretty much on hold until after Christmas.  Then I will try to bleed the Dual Booster Setup.



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Re: Problem with Dual Remote Vacuum Boosters

Post  Hotrodz of Dallas on Fri Dec 15, 2017 8:36 am

Looking at the pics, there appears to be a cluster of brake lines on the right side of the engine going into what was the battery area. I assume that's where the vacuum booster is. There could be a lot of air trapped there since the lines are much higher than the master cylinder.
I have used big reds on a few 944's using the stock master cylinder, and they work great. With the LS swap car, I will only use a hydroboost setup. I've tried electric boosters and remote vacuum boosters, and have never got them to work as well as a hydroboost. The initial cost of the hydroboost is a bit high, but the way the brakes work with it far outweigh the cost.
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Re: Problem with Dual Remote Vacuum Boosters

Post  johntorg on Fri Dec 15, 2017 8:59 am

Thanks for the input. You are correct, there really is a rats nest of brake lines at the booster. I will jack up the left side of the car when I attempt the bleed. I already own a mustang hydroboost. if I can't get the vacuum system working. Another issue may be vaccum level with the cam in the LS1. It appears to be about -15, I am not sure if this is sufficient.
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Re: Problem with Dual Remote Vacuum Boosters

Post  Hotrodz of Dallas on Fri Dec 15, 2017 9:09 am

My wifes 04 GTO with a 5.7 LS has a pretty big cam in it. The vacuum brakes work fine. 15" of vacuum is actually pretty good.
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Re: Problem with Dual Remote Vacuum Boosters

Post  johntorg on Fri Dec 15, 2017 9:35 am

Thanks, good to know.
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Re: Problem with Dual Remote Vacuum Boosters

Post  Porsche951toLS3 on Tue Dec 11, 2018 12:37 am

I have been following this post and would like to know the outcome of using remote brake boosters please.
I found this in my search:
https://techtalk.mpbrakes.com/boosters/remote-mounted-brake-boosters-vacuum-booster

I will be calling for price, but I would like opinions and if you got it working or not.

Thank you for any information you have.
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Re: Problem with Dual Remote Vacuum Boosters

Post  johntorg on Thu Jan 03, 2019 12:12 pm

I have the system working. I had to power bleed the system and now have a consistent pedal. The brake effort is better than unboosted, but higher than my other car with hydroboost.
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Re: Problem with Dual Remote Vacuum Boosters

Post  johntorg on Sun Jan 06, 2019 8:49 am

I found a price on the dual remote booster.  It's $795, but currently out of stock.  I suspect the biggest issue on any of the sysems is the bore size of the master cylinder, giving either too much or too little pedal travel.
https://www.mpbrakes.com/pc_product_detail.asp?key=2BFE78F8695F4586AC70FD356397FEAB&catid=6FF897C3513C43EC9060A9AB08A490F7
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Re: Problem with Dual Remote Vacuum Boosters

Post  Rich L. on Sun Jan 06, 2019 10:26 am

That's an interesting product. Cool you got it working! The instructions have text about the possible need for a residual valve if the spongy pedal feel comes back after 24 hours.

All the way at the bottom:
https://www.mpbrakes.com/images/MPB-F200-45.pdf

I might look into getting one of those. Keep us posted and good luck.

Rich
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Re: Problem with Dual Remote Vacuum Boosters

Post  johntorg on Sun Jan 06, 2019 11:48 am

That is not the system I'm using. I think the issue is that the remote boosters I am using have 5/16" master cylinders and put out 820 PSI. They are designed for English cars with 4 drums or a disk/drum setup. I found the above setup while researching a better setup for my track car. The current remote booster system works OK for the street, but I am not sure how it will work on the track.

My setup uses 2 boosters similar to these.

https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2047675.m570.l1313.TR0.TRC0.A0.H1.TRS1&_nkw=Remote+Brake+Booster&_sacat=0

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Re: Problem with Dual Remote Vacuum Boosters

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