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914World.com _ 914World Garage _ Brake Upgrade Success!

Posted by: Eddie914 Jan 22 2004, 07:09 PM

Thanks for all the helpful advice I received from everyone on the board!

I recently purchased a '71 914/6 2.7. The car was a 1.7 converted by the PO. Pretty rough but with a bunch of nice parts.

The original 914 rear brakes were seized solidly. A friend donated a set of freshly rebuilt of '79 911SC rear brakes (thanks Harry!) which upon initial inspection did not fit!

The 5 lug conversion to the original rear hubs stretched the metal enough that the outer diameter of the hub was greater than the inner diameter of the 911SC brake rotor. A little grinding fixed that ... but then there was minimal clearance (like 0.001") between the friction surface of the rotor and the caliper mounting tab on the swingarm. A 5mm wheel spacer between the hub and rotor provided nearly perfect spacing. Adding a 0.050" washer between the 911SC caliper and the 914 mounting brackets centered the calipers perfect.

Ate Super Blue Brake Fluid and Porterfield R4 brake pads finished off the installation. The rubber brake lines were also swelled shut so a set of Stainless Steel braided brake lines were installed at the same time. I have not had a chance to get the pads bedded in and all the air out of the lines but initial impressions are pretty good. When I get the car licensed, I'll be able to drive more than just around the neighborhood!

Now the $39 question ... The 914 now has 911SC calipers and rotors front and rear, with matched Porterfield R4 pads. Should I remove and/or replace the stock brake proportioning valve? The car will primarily be a track car but will be street legal (sort of) and oc

Thanks Again!

Eddie

'71 914 2.7

Posted by: SirAndy Jan 22 2004, 07:44 PM

since you upgraded front and rear you might get away with the stock prop. valve.
do some testing, don't be afraid of rubber marks on the asphalt

what you don't want is the rears locking up before the fronts, but you also don't want the fronts do ALL the work.
try to figure out where the car is right now and then decide.

- if the front get's too much, just replace the Prop. valve with a T.
- if the rear get's too much, get a aftermarked adjusteable valve.

Andy

Posted by: rhodyguy Jan 23 2004, 08:35 AM

welcome to the site eddie. another seattle member. our numbers (locally) are growing.

kevin

Posted by: DNHunt Jan 23 2004, 09:01 AM

Eddie

Welcome, I read your post earlier and never noticed your location. Nice to have another local. Most of us are NARP's (4's) but we have fun.

I second what Andy said. You'll have to try it and see how the balance is. I kinda prefer more front bias. I don't like to go backwards unless I'm in reverse. Any way when I increased front brakes I was able to adjust the stock proportioning valve to a bias I liked. I know most people advocate a T for what I did.

Good luck

Dave

Posted by: J P Stein Jan 23 2004, 11:24 AM

An adjustable proportionimg valve will get you where you want to go. The stock valve or a T "might" work.

I grew up in West Seattle.....well, grew older

You're officially invited to my annual gathering of lunatics, Feb 21, down here in Vancouver, WA.

On display:

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Posted by: rdauenhauer Jan 23 2004, 11:27 AM

Here Here! Welcome. I am in sort of the same boat Eddie but since I plan on just using S-calipers on the front, recently picked up a "T" from fellow lister James Adams. Now waiting for some dry roads to do some testing.

Posted by: J P Stein Jan 23 2004, 11:44 AM

Rich:

I tried "just using S calipers in the front".
It didn't work for me. The rears were just along for the ride. Your results may vary .........

You're invited, also.

Posted by: airsix Jan 23 2004, 02:32 PM

Eddie & Others:

Other factors would be engine weight, tires, & pads. I'm building a 2.7, but in the mean time I'm running around with the old 1.7. Combined with SC brakes on all fours and 245's in back = rears lock first unless I dial in some bias on the Wilwood proportioning valve. Now, Eddie and JP have more weight out back and might not experience that, but with the light -4, big brakes & wide tires out back - I need a little bias. A 'T' would be a no-go for me.

-Ben M.

ps - the stock prop. valve is a POS. I hate them. If I want to stand on a spring I'll get a pogo stick.

Posted by: rdauenhauer Jan 23 2004, 03:59 PM

JP thanks Im trying to work it into my Schedual. Im interested in details on your experiance. Pads? T or OE prop valve? Along for the ride means = complete front Bias and no actual rear brake force?

Posted by: J P Stein Jan 23 2004, 09:47 PM

S fronts, stock rears ....Wilwood porp valve wide open. After 18 or so months, I could still see the machining marks on the -6 rotors.....after an AX pass and I could hold my finners on the rear rotors.

I went ot 911 M rears, porp valve wide open. There is just a touch too much rear bias now.....it tends to pitch the rear out just a touch while agressivily trail braking....not a bad thing for AX...every once in a while, I can catch the slide with the throttle