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Posted by: larss Apr 29 2013, 06:04 AM

My stock 914/4 -72 handles quite well on straight roads but if I turn it into a slight bend where there is any kind of small bump it tends to loose the track, it rattles a bit in the front and comes out in a new track

The front end is all stock except for new Bilstein gas shocks (all around) and quite a bit lowered to (almost) match the rear end where it is sitting a bit.

Thought this would disappear with the new absorbers but sadly it just made a small improvement. Tyres are worn 185/65's on Pedrinis 5½. No sway bars.

What are the first things to check?


/Lars S

Posted by: SUNAB914 Apr 29 2013, 06:10 AM

Lowered in front, need bump steer kit.

Posted by: FourBlades Apr 29 2013, 06:53 AM

You inner and outer tie rod ends and balls joints could be worn out.

40 year old rubber bushings get wallowed out, causing the rattling.

Rattling is not caused by bump steer.

I have lowered my blue car until the a-arms are almost level and it does not bump steer at all.

Get some (lemforder) turbo tie rods and it will totally take care of the problem.

John

Posted by: larss Apr 29 2013, 07:09 AM

What do I have to do more than bolt the spacers in, (except for adjusting toe-in)?

Is the hole for the steering shaft boot large enough to take a 10mm lift of the rack?

/Lars S

Posted by: larss Apr 29 2013, 07:09 AM

Many thanks John!
Sorry I used the wrong word it does nott rattle (no noise present) but rather a quick wobble.

/Lars S

Posted by: Krieger Apr 29 2013, 07:48 AM

Check your wheel bearings to see if they are tight.

Posted by: kg6dxn Apr 29 2013, 08:00 AM

Sounds like bump steer to me too.

Posted by: larss Apr 29 2013, 08:04 AM

Thanks Krieger!

I have checked the bearings, like to have a just noticeable minimal play to ensure they are not to tight.

/Lars S

Posted by: larss Apr 29 2013, 08:06 AM

Thanks kg6dxn!

What do I have to do more than bolt the spacers in under the rack, (except for adjusting toe-in)?

Is the hole for the steering shaft boot large enough to take a 10mm lift of the rack?

/Lars S

Posted by: kg6dxn Apr 29 2013, 08:12 AM

Some do the spacer kit and some do turbo tie rods. The spacers are cheapest to try first. Yes the boot will be OK.

Posted by: larss Apr 29 2013, 08:17 AM

Thanks again!
Yes and if I have to fit the turbo tie rods later the spacer kit is good to keep also then (?)


/Lars S

Posted by: rhodyguy Apr 29 2013, 08:23 AM

if you're going to have an alignment done you'll want the tie rod package and bump steer kit in place or do the alignment twice. if you have a 'pro' do it the second alignment costs will cover the tie rod and end package.

Posted by: rick 918-S Apr 29 2013, 08:42 AM

Bump steer kit and tie rods then alignment

Posted by: r_towle Apr 29 2013, 09:21 AM

show a side picture of the car stance.

If the lower a-arm in front sits out of level, where the ball joint is hinger than the torsion tube....then you need to adjust the car back up just a hair.

Bump steer spacer kits may not be required if you do a few things.

Get the a-arms adjusted properly.
Good bearings, nice and tight
Good tie-rods
Get some toe-in on the front end.

When you just lower the car, it toes out.
That makes it skittish and bump steer is drastically increased.

Simple to check.
Straighten the wheel so both wheels are aiming forward.
Lay a block of wood on the outside of both wheels
Measure from side to side from one block to the other to see if you have alot of toe out.

This is crude because rubber wheels have way to much variation to be accurate, but it should give you a good idea.

I also saw a trick of laying wet newspaper down on the floor in front of both wheels, then gently roll the car over the newspaper.
The car (maybe) will twist the newspaper in the direction of the toe angle...

So, you may not need the bump steer kit.
I dont have one, never did.

I had my car so low the a-arms hit the weld flange in front.
I adjusted the alignment exactly to some toe-in, about 1/8 inch overall to compensate...all it well.

The toe- out is what makes it feel like you are being dragged around from one rut to the next.

Slight toe out is great for autox and quick turn in, but it sucks to drive around town, and it wears the inside edge of the tires out quick.




rich

Posted by: luskesq Apr 29 2013, 09:32 AM

First, I'd check the camber, caster, and alignment because that could affect your tracking. If okay, move on to inspecting and replacing parts suggested. If not okay, take care of that issue prior to throwing money at parts. Here is a DIY thread discussion on how to check and align: http://www.914world.com/bbs2/index.php?showtopic=202671.

Very simple.

Good luck,

Keith

Posted by: larss Apr 29 2013, 10:56 AM

Thanks everyone!

I have made several toe-in checks on different floors with my home alignment tool; Always the same result the toe in is about 3/8".

The center of the A-arm is about 1½ " lower at the outer end then at the inner.
The tie-rod center is about ½" lower at its outer end than at the inner.

However i just checked the camber which was 0 at the right side but just under -3/8" on the left, the upper side of the rim is leaning OUTWARDS!

Isn't camber supposed to be around 0 for a car like mine?


/Lars S

Posted by: Rand Apr 29 2013, 11:38 AM

I'm not buying the bump steer. It's just not that low. My car is lower than that and I don't have bump steer issues. I think something is sloppy somewhere.

Posted by: ThePaintedMan Apr 29 2013, 11:47 AM

The pictures really help. And your description of the camber does as well. You should never have positive camber (top of the tire leaning out) on just about any modern vehicle, except maybe an old tractor. Sounds like you need to get it aligned.

However, everyone's advice about replacing components still stands. Inspect everything for wear and play and before you get it aligned, replace anything that you suspect is worn out. Otherwise you'll pay to have it done twice.

Posted by: larss Apr 29 2013, 11:51 AM

Thanks!

About how much negative camber should I have in inches measured on a 15" rim?

And also, I've made all measurements with about ½ filled fuel tank, is it supposed to be empty or full or what?


Thanks again!


/Lars S

Posted by: r_towle Apr 29 2013, 12:56 PM

haha,
Its not bump steer..

If anything, its to high in my opinion, but that is not your problem right now.

Do you have any play in the steering wheel at rest?
Any clicks when you shake it back and forth?

Wear items.
Bearing at steering column.
U-joints under dash at steering column
Rubber damper at joint under gas tank
Tie rod ends, both inner and outer.
Bearings
LAst but not least, steering rack.

I replaced everything on the list with new parts.
It was the ring and pinion in the rack.
I rebuilt the rack and all is well.

rich

Posted by: larss Apr 29 2013, 01:14 PM

Thanks Rich!

There is no significant play but a "soft" click can be noticed when shaking it around center, first i thougt it was one of the U-joints under dash but changing it did'nt make it better.


/Lars S

Posted by: mepstein Apr 29 2013, 01:34 PM

looks high in the front

Posted by: FourBlades Apr 29 2013, 06:11 PM

This is what low looks like.

Look at where the wheels are at the top of the fender arch.

This car has no bump steer kit and handles perfectly.



I admit I love this picture of my car and was just looking for an excuse to post it again. Does that make me sick person?

It does? Ok, so what!

By the way, that is a really nice looking 914 you have...

John

Posted by: messix Apr 29 2013, 06:58 PM

isn't that kinda like what mcmark had when he found the steering "isolator" between the column and the rack about to fall apart ???

Posted by: r_towle Apr 29 2013, 08:00 PM

Have you checked the tie rod ends and bearings?
If yes, it's the rack.

It's an old age issue that the rack gets worn right in the middle where you center the wheel and that creates a click, and the car will wander.

Did you say you already replaced the tie rods with turbo tie rods?

Posted by: Spoke Apr 29 2013, 08:12 PM

This seems like it's quite toed in. When I set my 914 and 911, I set it to 1/8". This is the difference between the front of the wheel and the back of the wheel, about 25" apart.

I don't have the 914 repair manual with me but I think the toe in is 20 min +/-10 min.

I got the above numbers from this article:

http://repair-manuals.blogspot.com/2012/01/porsche-1963-72-wheel-alignment-repair.html

According to Pelican's tech article, this would be just about 1/8".

http://www.pelicanparts.com/techarticles/home_toe_in/home_toe_in.htm

3/8" would equate to 53min or 2 1/2 times more toe than specified.

Posted by: r_towle Apr 29 2013, 08:15 PM

Total toe in should be 1/8 of an inch at the front and zero in the rear.
Camber should match side to side.

Posted by: larss Apr 30 2013, 12:06 AM

Thanks everyoune for your input it has been a great help to me!

By locking the lowest part of the steering shaft I can see that there is a minor play in the lower U-joint (the one just above the pedal cluster).
Are theese joints ment to be 100% free of play?

/Lars S

Posted by: Porsche930dude Apr 30 2013, 08:35 PM

i agree way too much toe. I measure my alignments at home by simply hooking a measuring tape on a uniform part of the tire tread and measure it as high up as you can front and back. that has proven to be quite accurate for me. way better than driving over a piece of paper anyway

Posted by: r_towle Apr 30 2013, 09:25 PM

They all are a bit loose.
I would suggest you align the car.

Look around here for the how to using strings, it is simple and very accurate.
Get the toe correct, especially if one side is way off.

You may be off on your camber and toe on one side of the car, and that will make it feel like crap.

Learn to do your alignment, or go to sears, get an alignment and some coffee while you wait.

All the wandering and wiggles will stop bothering you if you can stay in a straight line again.

You mentioned above that one side is way off on camber, it may also be way off on alignment. Did you possibly hit a curb or ditch with that side?

Rich

Posted by: larss May 1 2013, 12:06 AM

Thanks everyone!

My camber is now triple checked OK, just a few mm on each side, the earlier was wrong due to uneven floor .

I have now set toe in to 1/8 and what a difference!Havn'tdriven so much yet but 1st impression is success.


I follow the Pelican article, have two angled sheet metal pieces with same widthasthetires (24"), the instructions are

Take the difference between the measurements of the front and rear of the tires then divide by 2 and that is the toe in/out per wheel in inches.

Spoke wrote above that
"...set it to 1/8". This is the difference between the front of the wheel and the back of the wheel, about 25" apart."

Which one is correct, Pelicans say to divede the diff by 2 but the other not...?
Edit:
Oh, yes Spoke refers to one wheel at a time but Pelican is about both wheels and the measurement has then to be divided by 2, right?

/Lars S

Posted by: Racer Chris May 1 2013, 11:14 AM

Total toe-in is the sum of the toe-in of both wheels.
About 1/16" total toe-in (1/32" per side) is sufficient if turbo tie rods have been installed. I measure at the wheel rim, not on the tire.

Posted by: r_towle May 1 2013, 11:34 AM

Dont use the tire.

I am not a fan of just using an angle piece because you could potentially put all the toe on one wheel and not know it.
Using strings (or a machine) gets you using the centerline of the car, and therefore adjusting BOTH sides identical.

Rich

Posted by: larss May 1 2013, 11:43 PM

I use angle sheet metal pieces but I dont use the tire but the rim for reference. I put the sheet metal at equal distance (about 1") from the rims most forward and most backward point and then do the measurements from the forward and back edges of the 24" wide sheet metal.
Of course using a machine is the best.


/Lars S

Posted by: larss May 2 2013, 04:19 AM

Found that the rack has a play in its outer right end, sideways and up and down, not in/out...putting this in a new tread.


/Lars S

Posted by: r_towle May 2 2013, 09:17 AM

Without using the centerline of the car, like a machine would do, or like running strings from front to back, you cannot know you are doing the front end correctly.

For a quick adjustment at a track event, it works.
For a baseline setup, it does not.

Get four jack stands or milk crates.
Run two strings parallel to each other front to back on the car.
String height needs to be at the centerline of the wheel.

Front and rear track widths are different, but you need the string to be the same distance on both sides in the front, and then again in the rear.

Posted by: andys May 2 2013, 11:25 AM

For at the track: Two people, duct tape, a pen, a measuring tape, and a reasonably level area.
1. Measure the lowest point of the undercarrage from the ground up at the rear of the front tire such that the tape measure will span from one tire to the other without obstruction. The lowest point on a 914 is at the rear. Some cars have the lowest point at the front of the tire, but I've found that is rare.
2. Wipe the rear part of the tires clean of dirt at the height in #1. Place a piece of duct tape 2 or so inches long and mark a horizontal line with your pen at the height measured in #1. Do both front tires. It's not important where the duct tape is placed right to left.
3. Make a vertical pen line intersecting the horizontal line; anywhere convenient is fine, both sides. You now have two crosshairs to work with. I like to use a ball point pen for the nice crisp lines.
4. Measure the distance at the rear of the tires at the crosshairs. For accuracy, it's best that person A align the tape measure at the 1" line, rather than at the hook. Person B should record the distance at the other side.
5. Roll the car forward until the crosshairs are at the front of the tires at exactly the same height as they were at the rear. Measure and record.
6. Make your adjustment and roll the car forward until the crosshairs are again at the rear. Measure, then roll the car forward and measure again to determine correction. Only roll the car forward for each subsequent measurement to keep the suspension and steering loaded in the same direction. If you're short on room, you can roll the car back , but past the starting point, then forward to start the process again. Oh, make sure the steering wheel is pointing straight....on race cars I like to clamp the steering wheel to insure it doesn't move.

I've used this method for many years, and the degree of accuracy ia way better that stringing, IMO. The only thing to compensate for, is that these measurements are below wheel center, so the toe values should be slightly less.

Andys