I just finished installing 911SC struts (Bilsteins) in my '74. I am having a couple of problems:

1.) The steering seems twitchy. Very sensitive. I took great care in not messing with the alignment. Anyone had this when converting to 911 suspension?


2.) I am having trouble bleeding the brakes. I do not own a pressure bleeder so I had to rely on the wife. After bleeding all four corners about (3) times, (always starting with the farthest to the nearest), I get a semi firm pedal. If I pump the pedal it will come up, even with just one pump. What do I need to do?

3.) This is not a serious problem but may relate to number 1.) above: The steering is a lot easier now. It has a very light feel, like power steering.

4.) Does anyone know what Bilstein strut was commonly used, heavy duty or sport, from the factory on SC's? They feel a lot stiffer than the original BOGE that I replaced but not as stiff as I expected.

Thanks,
dave

I don't think you can just replace the struts without affecting the alignment. I would never trust the alignment afterwards myself.

The Bilstiens should be gas struts and the Boges should be normal shocks. That should be like adding an extra spring into the suspension (basically preload anyway).

Brake bleeding, did you ever let the reservoir get so low as to suck air? Did you drain the calipers? Are you still getting bubbles?

You should get an alignment. It would be nearly impossible to keep the front end aligned after such an extreme change.

You did change the alignment, whether you meant to or not. Sounds like you have a lot less caster than you used to (lighter steering), which is controlled by the fore/aft position of the top of the strut. If the car doesn't pull to one side or the other, at least you got the camber and caster the same on each side.

Make an appt with a good alignment shop.

As for the bleeding the brakes, try this: place a very snug fitting clear tube onto the bleeder nipple, and hold the open end of the tube up above the reservoir (drape it over the fender with the trunk open). Remove the cap on the reservior. Open the bleeder nipple. Wait. Fluid will rise up the clear tube fairly slowly. You'll eventually see bubbles in either the tube or the reservior. The fluid will slow as it rises, and will eventually stop when it becomes level with the reservior (keep adding fluid).

Repeat on the other front caliper.

Sometimes, once there's fluid in the tube, you can also pump the brake pedal to help things along.

This "gravity bleed" system generally works well, though it doesn't work nearly as well with low-mounted master cylinders.

Speed Bleeders (bleeder nipples with one-way valves) seem to work for some people. They don't seem to help much for me.

Speed bleeders. I like them. still need a piece of tube going up over a suspension piece and then into a catch can.
you can see the ait bubbles come out.
Trick is to not fo too fast as it will cause foaming. Then you will NEVER get it out till it settles.

Yea re-do the alignment. you ain't that good and no telling if the struts are EXACTLY the same as the units you took off.

James, I think you are the only other person I have seen recommend this - I was just getting ready to reply when I saw your post It can be a slow process - I have even taped the hose up to the fender top and left it while I went to get lunch... it works really well though. I have done two calipers at once, making sure the fluid is a little overfull, and walk away.
I have a power bleeder now because I have no patience, but I found this trick must easier than all the pumping.

Wouldn't this leave the hydrophilic brake fluid exposed to the air for too long though??

Just wondered....

This thing has a SERIOUS Toe problem. The steering knuckle on a 911 strut versus the 914 strut is WAY OFF. He has excessive toe.

Repeat to yourself: I must get an alignment.. I must get an alignment.

There is NO way in hell you can make such a drastic change to the car and not need an alignment.

Now.. you can set TOE at home with a simple tape measure, but unless you have an angle finder or a string setup, you wont get camber.

I would like to see someone design a string setup that allows me to set thrust angle at home..

B

I am guessing you are referring to whether it gathers moisture or not... and this is my opinion, backed with no real fact or statistical data, so it might not even be worth 2 cents, but frankly on a daily driver, most folks don't change the fluid often enough for it to even matter, and won't be on the brakes hard enough to be worried whether the fluid will boil at the wet or dry temp. That said, I also do not know how quickly moisture can be absorbed, so it may make a difference in the boil pnt or not, but if you aren't flushing every 6mo. let's say, then what would it really matter if you were at the wet point at day one or day 31 or day 181?

As for a race car, I crack open a new can and flush often and use a power bleeder to minimize exposure. I only keep an open can to take with me in case I need to quick bleed at the track between rounds and flush every few track days because I really need to have the additional temp range under those conditions.

A streeter, I have personally never paid any attention to whether I would need the dry v. wet BP. and rarely flush frankly. Seems like such a PITA for a daily driver and just part of the system for a racer In fact, when I have flushed my drivers, I typically use the left-over open can from the race car!

just mark you center lines (takes a lot of time and measuring, but you only have to do it once), set your parallel strings (lasers are cheap now) and get to work??? that's what i've done...

Hi Brad

One thing I would add on the bleed would be:

Once you get the alignment, drive the car a bit. This is assuming you have bled them and they are OK but not what you would call 'GREAT'. I like to drive and find a vacant lot where you can do some serious panic stops.

After about a week... rebleed. This seems to get the air out of the proportioning valve.

Always bleed a street car every year. I've torn apart hundreds of calipers. Fresh fluid makes a huge difference in the condition of your calipers. After 30 years some look like death waiting to happen and others can literally look new.

Your choice, your life. I would bleed at least once a year.

I thought that was the first step in doing a string alignment at home.

When I did string alignments, I would find the centerline of the suspension pick-up points front and rear, then mark the chassis where this spot was. I could then drop a plumb bob from that point both front and rear.

I would then snap a chalk line between the two points.

This line would be the centerline of the vehicle.

The two stringlines running front to back on either side of the car would be set off this vehicle centerline.

From the two strings, one would measure the distances from the string to the front and rear edge of the rim. The difference in measurement can be used directly as inches of toe or converted into degrees, minutes and seconds.

Since the two parallel lines are equi-distant from the centerline of the vehicle, you are effectively setting the thrust angle to zero.

(The thrust angle is the angle from the vehicle centerline that the rear drive wheels are pointing. If the strings are parallel and equidistant from the centerline of the vehicle and each rear wheel is measured to have the same toe, then the thrust angle would be zero.)

My machine makes it much easier and quicker to get accurate results. After I had it calibrated, I'm the only one that uses it and it stays nice that way.