944Hybrids: 924/944/968 and 928 V8 Conversions
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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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Hydro boost help

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Hydro boost help Empty Hydro boost help

Post  dsrracer Mon Oct 17, 2016 1:24 pm

I've bled the hydraulic system and the level has stabilized. No noise. I've bled the brakes with a pressure bleeder. Now the brakes are on all the time. I can overcome it with the engine on a lift but can not turn any of the wheels by hand. Any ideas are very welcome. I thought I was almost ready for the first drive.
dsrracer
dsrracer

Posts : 66
Join date : 2015-11-04
Location : Benton Ks

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Post  sharkey Mon Oct 17, 2016 2:46 pm

does it change between running and not? all 4 wheels or just 2? only thing that comes to mind is the pushrod from the pedal to hydroboost is too long, or the pushrod in the hydroboost to the master cyl is too long. this would keep the brakes applied.

sharkey

Posts : 714
Join date : 2014-11-21
Age : 39
Location : Abbotsford BC

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Post  dsrracer Mon Oct 17, 2016 4:03 pm

It doesn't change between running and not running. It is all 4 wheels. I cracked a fitting quickly and let the pressure off. First rear - rear wheels freed up, then the front- front wheels freed up. I applied the brakes and it locked up and stayed locked again. I'll check the link length to the pedal. The link to the stock 944 MC was a TPC part. I didn't check its length (not sure what the length should be) but I can disassemble and check it.
dsrracer
dsrracer

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Post  sharkey Mon Oct 17, 2016 4:13 pm

the pushrod between the pedal and booster should allow for some freeplay in the pedal. basicly you should be able to unhook the pushrod from the pedal without fighting pressure from the booster.

sharkey

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Post  dsrracer Mon Oct 17, 2016 4:48 pm

I'll check it- thanks!
dsrracer
dsrracer

Posts : 66
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Location : Benton Ks

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Post  sharkey Mon Oct 17, 2016 6:54 pm

if that seems ok unbolt the master cylinder from the booster with everything hooked up while the brakes are locked up. if while unbolting the brakes free up and/or the master cylinder is being pushed off of the booster, something is wrong with the pushrod length coming out of the booster

sharkey

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Post  Jasonscottw Mon Oct 17, 2016 10:54 pm

Seems like a pushrod issue if there isn't a difference between engine running vs. not running. What was the length of the pushrod? I milled two of them, so I can compare to the one that is not installed-
Jasonscottw
Jasonscottw

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Post  dsrracer Sun Nov 06, 2016 4:55 pm

I've continued to have brake problems since the initial post. I thought I could fix them and have tried several things without any success.
I sent Kent a question but thought Id share the problem for any advice.  I have extended the rod outside of the unit toward the pedal and raised the front end pretty high and bled the system as recommended. With everything  cold I have no braking force applied. I live about a mile from a major road and I'm able to drive slowly (15 mph) the entire way without touching the brakes at all but within the mile they are dragging without ever even touching them. After turning around I am unable to return the mile without the brakes dragging heavily- again never touching them even once. I crack the brake lines which frees them and I drive home. Once I get home they are clamped on again and I can't push the car. After cooling they free up. Again, this without having ever applied the brakes. I observe no movement of the pedal- it stays out where I left it whether the car is running or not. 
When assembling the master cyl to the adapter block it compresses the mc cyl approx .66. It is extended into the counterbore of the aluminum block and hits the forward face of the hydro boost, so it's not hanging up 'early' in the adapter block. I'm wondering whether this is closing the ports to the reservoir and trapping the fluid in the brake line during the assembly process.  It's clearly a function of driving (and the hydro boost running) and not of brake application. Hopefully someone has an idea. Btw the block thickness is 1.255 - I don't know whether that the correct thickness or its too short. There is nothing in the old vacuum booster that would preload the shaft at all during assembly. Thoughts?
dsrracer
dsrracer

Posts : 66
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Location : Benton Ks

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Post  dsrracer Sun Nov 06, 2016 4:57 pm

BTW- the push rod length was 4.8 in. I forgot add that.
dsrracer
dsrracer

Posts : 66
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Location : Benton Ks

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Post  dsrracer Tue Nov 08, 2016 4:31 pm

I finally got the brakes working flawlessly. With a long conversation with Kent we determined there was a sleeve in the hydroboost that was stopping the MC from completely extending (thanks Kent!).
First drive of about 15 miles was flawless. I'll do a shakedown of all bolts and clamps now. I used to race SCCA and there seems like there is always something that you leave loose or vibrates loose but I'm super excited with the conversion, the quality of parts from TPC and the technical support. Anyone thinking about taking the plunge should do it!
dsrracer
dsrracer

Posts : 66
Join date : 2015-11-04
Location : Benton Ks

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Post  944LST Sat Jun 13, 2020 1:20 pm

Im having the same issues with mine, basically its fine when its off but the pushrod going into the clevis pulls into the booster when i turn the car on.Any advice would be great!

944LST

Posts : 1
Join date : 2019-06-07

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