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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Hydroboost without power steering rack!

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Hydroboost without power steering rack!

Post  Lemming on Tue Jul 01, 2014 4:02 pm

Ok, I was trying to set this up and just got off the phone with Tallon Hydraulics. He said that without the power steering rack, you will not build any pressure in the hydroboost system and it is useless Shocked  He stated that some drag racers using a relief valve but that is not advisable for road racing and or a daily driver.
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Re: Hydroboost without power steering rack!

Post  Lemming on Tue Jul 01, 2014 4:25 pm

Ok, so according to this thread http://944hybrids.forumotion.com/t696-hydroboost-without-power-steering?highlight=hydroboost

I have to put a restrictor on the outflow from the hydroboost.  Does anyone know the orifice size?

Who is currently running this setup??????
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Re: Hydroboost without power steering rack!

Post  948inVA on Tue Jul 01, 2014 5:37 pm

I have mine set up without the rack or restrictor and it builds pressure just fine.. where is that guy getting his information?

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Re: Hydroboost without power steering rack!

Post  Lemming on Tue Jul 01, 2014 6:04 pm

supes6 wrote:I have mine set up without the rack or restrictor and it builds pressure just fine.. where is that guy getting his information?

Not sure.  Can you describe your setup?

Which power steering pump are you running, GM or Turn one?  If turn one are you restricting flow?

He also said that with a flow rate of 3 gpm of the GM pump that the setup would foam like crazy.
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Re: Hydroboost without power steering rack!

Post  948inVA on Tue Jul 01, 2014 6:36 pm

I'm using the GTO pump, mustang hydroboost, mustang master cylinder, mustang prop. valve. High pressure line goes from pump to hydroboost. For that I modified the line that came with my HB - cut the metal section at the pump end, added a flared union, and mated it to a section of 3/8" metal fuel line with the GM o-ring end already formed. Then there are 2 outlets from the hydroboost, which go into a tee fitting and then back to the reservoir.

So far it's been pretty reliable for street duty, I've been running it for close to 2 years with no issues. I can tell the brake bias is a little off but it's not really an issue on the street. The power assist is definitely more powerful than it was with the stock vacuum booster.
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Re: Hydroboost without power steering rack!

Post  Lemming on Tue Jul 01, 2014 6:56 pm

Ok, the guy had me in a panic.
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Re: Hydroboost without power steering rack!

Post  Lemming on Wed Jul 02, 2014 7:29 am

Excellent hydroboost tutorial at http://www.brakeandfrontend.com/Article/38431/operation_diagnosis_and_repair_of_hydroboost_power_assist_systems.aspx

Based on this information, I can see why having some back pressure on the power steering line (gear port) would give greater braking assist.

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Re: Hydroboost without power steering rack!

Post  docwyte on Wed Jul 02, 2014 8:52 am

You need the Turn 1 pump for track use. You also need a PS cooler for track use, along with an adjustable proportioning valve...

I can't comment on the manual rack, I've always had a powered rack...

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Re: Hydroboost without power steering rack!

Post  Lemming on Wed Jul 02, 2014 10:40 am

docwyte wrote:You need the Turn 1 pump for track use.  You also need a PS cooler for track use, along with an adjustable proportioning valve...

I can't comment on the manual rack, I've always had a powered rack...

I thought people were using the turn one pump because of the PS rack, not the hydroboost. If it's an issue of flow, I can buy a flow reducer (3 - 2 gpm) on summit?
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Re: Hydroboost without power steering rack!

Post  Dawgz83948 on Sat Jul 05, 2014 3:44 am

Hey guys. Sorry I'm late to the party, I'm out of country for another week. I ran BMW hydro boost with the manual rack. Initially we tried no oriface, which equalled no boost. Then I closed off the rack tube, which resulted in the destruction of the accumulator. Smile I drilled out a 1/8" hole and increased the size 3 times in very small stages based on pedal effort and power steering pump complaints at higher rpms.
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Re: Hydroboost without power steering rack!

Post  Lemming on Mon Sep 15, 2014 1:58 pm

My HB worked great this past Saturday without having to add any restriction after the HB unit. In fact, I would say that the unit is over boosted, all I need is my big toe to stop the car!

Setup: Stock LS1 PS pump, 8-an line from pump to HB, two 6-an lines from HB to cooler, then 8-an back to the pump. PS fluid temps reached 207 after a full session (Redline fluid). The cooler does not currently have a direct flow of air from the front dam, that may change.
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Re: Hydroboost without power steering rack!

Post  xschop on Sun Apr 26, 2015 5:47 am

What is the final word on factory F-body PS pump, Mustang hydroboost and manual rack?

We are going to a de-powered rack on a local LS swap.
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Re: Hydroboost without power steering rack!

Post  Lemming on Sun Apr 26, 2015 8:55 pm

Yes, it did work. You need to put a cooler on the system to keep temps down. In the end, I did not like the feel of the system, very hard to modulate near threshold braking. I don't think the 1" master for both front and back worked well on my system (Integra 6R front / 951 rear calipers). Even with a proportioning valve on the rears, I could never dial enough rear brake out of the system. Even tried running non-agressive pads on the rear to no avail.

By the way, my HB system (with cooler and mount) are up for sale.
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Re: Hydroboost without power steering rack!

Post  xschop on Mon Apr 27, 2015 8:09 am

Good news actually Tim. To be specific, do you have a set of front 951 calipers on your rears?
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Re: Hydroboost without power steering rack!

Post  Lemming on Mon Apr 27, 2015 10:19 am

No, using rear 951 calipers in the rear.
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Re: Hydroboost without power steering rack!

Post  xschop on Mon Apr 27, 2015 10:48 am

Just confirming, because your situation sounds just like how the Wildwood 1" tandem MC behaves. Has anyone tried adapting the 951 MC to the Mustang hydroboost?

I'm modding his power rack and he's got the Mustang unit installed already......










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Re: Hydroboost without power steering rack!

Post  Lemming on Mon Apr 27, 2015 11:02 am

I seem to remember someone on this cite making an adapter, but can't remember who that was.

For the 6R/951 caliper setup, the following MC sizes seem to work the best: 5/8 front, 3/4 rear. I tried 3/4 on both ends, but was not getting enough pressure to the front end, thus I went down 1/8.
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Re: Hydroboost without power steering rack!

Post  phlip on Mon Apr 27, 2015 5:25 pm

I copied 948's adapter to mount 951 master to ford hydroboost.
Look in this thread http://944hybrids.forumotion.com/t1689p90-hydroboost-mounting-plate

Ive only driven a little cause I have a clutch vibration thats pissin me off, But the brakes work well.
Bias is very neutral.

My fab guy may consider making more, but its probably not hard to figure out.
Only draw back I can see is i cant fit my tower brace

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Re: Hydroboost without power steering rack!

Post  Techno Duck on Tue Apr 28, 2015 7:53 am

The adapter 948 made to retain the stock master is a great idea. Like Lemming said the Ford Mustang master cylinder changes the pedal feel quite a bit. I am using S4 front and stock turbo rear calipers and the pedal travel is quite short now due to the larger 1" bore. The bias feels fine though between the front and rear; i have it dialed in using a Tilton bias valve. If i remember right i have it set at one click forward from the middle position.

It took some getting used to the pedal, but overall i have been happy with how they feel on the track.

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Re: Hydroboost without power steering rack!

Post  xschop on Tue Apr 28, 2015 4:41 pm

What are the piston sizes on the front S4's?
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Re: Hydroboost without power steering rack!

Post  Lemming on Thu Apr 30, 2015 8:03 am

xschop wrote:What are the piston sizes on the front S4's?

IIRC they are 36/34 mm. Not 100% sure.
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Re: Hydroboost without power steering rack!

Post  xschop on Thu Apr 30, 2015 8:17 am

Yeah they are somewhere in that vicinity. I rode in an LS swapped car with mustang hydroboost and the LS 430 calipers (43/43) upfront and factory NA single piston calipers (36mm iirc) and it was awesome braking and no rear lock-up.

When I did my 928 LS1 swap, I copied this exact setup because vacuum booster stayed (23mm master) and the braking was phenomenal as well. The rears could have used a little more bite, but wasn't worth messing with.
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brakes

Post  kevin924kevin on Thu Apr 30, 2015 11:42 am

Hello, my Big Blacks are 44mm/36mm. They are the same as the Big Reds, just a different mount set up. My rears are S2 4piston at 30mm/ 27mm. This should work with the hydroboost.
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Re: Hydroboost without power steering rack!

Post  Rich L. on Thu Apr 30, 2015 10:21 pm

There are "Big Reds" (993tt), "Big Blacks" (928 GTS) and "S4 brakes" (928 S4, 944 Turbo S, 944 Turbo/968 w/ m030). They all have the same piston sizes, 44/36mm.

Rich
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Re: Hydroboost without power steering rack!

Post  xschop on Fri May 01, 2015 5:26 am

The Audi S8 front calipers are 44 x 40 with larger pads than the Big Reds or Blacks.

I will be working on a set soon for a 928S and Late 944 that adapts a full set of Lexus monoblocks calipers on factory rotors. The rears are dual piston 38mm.
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