Spring perch spanner
11-03-2005, 10:43 AM
#1
Racer
Thread Starter
Spring perch spanner
Can anyone tell me the correct size for the "c spanner" used for adjusting the spring perches (964RS) and the best source for one? Also I hear that the a arm bushes can be swapped out with poly bushes anyone have more info on those too? Anyone have any good links for home corner weighting etc too. I am in the UK so UK sources would be nice. Thanks.
11-03-2005, 08:02 PM
#2
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I worked on a DIY corner balance that involved connecting the rear tire schreader valves with a rubber hose and an air flow meter. Procedure (still some bugs, but it will work when I get to a flat garage floor again):
1. Raise the rear, and connect schraeder valves on both rear tires with a rubber hose.
2. Open valve in rubber line to equalize pressure side-to-side, and then close it again.
3. Lower car to ground, and exercise the suspension to settle things.
4. Open the valve in the hose line, and observe the direction that the air flows (it will flow from the heavy side to the lighter side).
5. Repeat same steps on the front. If the air flow direction is reverse of the rear, the corner balance is pretty far off.
6. Adjust highest corner until the air flow is in the same direction and similar magnitude on both front and rear.
Note you do not need to be in the car to perform a corner balance, and you are unlikely to get all four to the same weight. The goal is simply to distribute the heavy side weight evenly to the tires on the heavy side. Corner balance is analygous to getting a 4-leg table to stop rocking - just raise or shorten one leg. and all four will sit evenly.
I will post a DIY with pics if I ever get back to a place where I have time and space to do projects (next Summer if all goes well).
1. Raise the rear, and connect schraeder valves on both rear tires with a rubber hose.
2. Open valve in rubber line to equalize pressure side-to-side, and then close it again.
3. Lower car to ground, and exercise the suspension to settle things.
4. Open the valve in the hose line, and observe the direction that the air flows (it will flow from the heavy side to the lighter side).
5. Repeat same steps on the front. If the air flow direction is reverse of the rear, the corner balance is pretty far off.
6. Adjust highest corner until the air flow is in the same direction and similar magnitude on both front and rear.
Note you do not need to be in the car to perform a corner balance, and you are unlikely to get all four to the same weight. The goal is simply to distribute the heavy side weight evenly to the tires on the heavy side. Corner balance is analygous to getting a 4-leg table to stop rocking - just raise or shorten one leg. and all four will sit evenly.
I will post a DIY with pics if I ever get back to a place where I have time and space to do projects (next Summer if all goes well).
11-03-2005, 08:30 PM
#3
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Springer, I'm with you right to the point of opening the valve in the hose line. Do you have the 964--- PN please? I'm going to order one tomorrow. I hope Sunset has this one in stock.
11-03-2005, 09:56 PM
#4
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On the main 911 email list there was a posting (just found it and I will include it) for corner balancing without scales. I haven't tried it but I'd be curious to know if Springer (or anyone else) could debunk it?
There is a method for corner weighting a car without scales using a
ruler/tape measure and a jack.
Here¹s how to do it...
Preparing
1. Put the car on level ground * dead level * this is critical * you may
have to pack one or two wheels to achieve this. The two measuring points
don¹t have to be level but you must know how much they are out from each
other so you can add/subtract that amount when taking measurements (more on
this in a minute)
2. Set the ride height you want for the car (adjusting spring perchs torsion
bars up or down etc)
3. Pick two points on opposite sides of the car that you know are level
(Being a race car mines well measured up and with bits not found on std cars
that I use to measure from) * you could use each end of the steering rack
(if you¹re sure its level with the car) or bolts where the A arms attach
toward the rear (rack end) of the car (* if you¹re sure the car isn¹t bent *
if it is, a decent corner weight will be damn hard what ever method you use)
or any other points that work for you that are level. I think for Porsches
around the rack area is best since there are lots of strong points that you
can be reasonably sure arn¹t bent and it is close to the middle (front to
back) of the car (desirable * but not critical)
Its also an idea, if its a track car, to fill with the amount of fuel you
normally use and to put the drivers weight equivalent in the front seat
(doing this actually leads to my car sitting slightly up on the drivers side
when I¹m not in it and sitting level only when I am in it * but its v light
<940kgs)
Measuring
3. Starting with the front weights. Jack the rear of the car up so the rear
tyres are just off the floor * measure vertically down to the ground from
your two measuring points * if there is a difference in the distance between
the floor and each measuring point drop the car off the jack at the rear and
jack up the front and adjust the spring perches (or torsion bars) so that
the distance between the floor and each measuring point is the same * you¹ve
now balanced the front .
I usually adjust the spring that is going to bring the ride height down (but
again its a race car) - after each adjustment roll the car backwards and
forwards to settle the suspension. When getting close to level I even leave
the car for half an hour or so as it will usually settle even more (one or
two mm) - ultimately this is the difference between very good corner weight
and an adequate one (whether using this method or scales). You have
finished the front when there is no difference (or at worst one or two
millimetres difference between the two measuring points and the ground)
4. Rear weights. Jack up the front of the car so the wheels just clear the
ground. Measure vertically down from the same two measuring points* if
there is a difference in length drop the car off the jack at the front, jack
up the rear and adjust the spring perches (or torsion bars). Again you are
looking to get the distance between each measuring point and the floor the
same or within one or two mm
The first time you do this will take quite a few hours (just like doing your
first alignment) but its pretty fast once you get the hang if it. In some
respects faster than using scales since you don¹t get sucked in to chasing
weight around the car.
Accuracy
When I heard of this technique I was pretty sceptical * its too simplistic *
I learnt it from a guy who is highly regarded for his ability to set up race
and tarmac rally cars (and his ability to drive them) hes been doing it like
this for 20 years. The first few times I used this method I immediately put
the car on the scales to check * contrary to my expectations * I had the
best corner weights I¹ve ever achieved including the cross weights.
Not being the sharpest tool in the tool shed its taken me awhile to figure
why it works so well but I¹ll leave that to list conjecture. Suffice to say
there are still plenty of sceptics out there and you can help your race
budget with a few bets here and there (every little bit helps)
There is a method for corner weighting a car without scales using a
ruler/tape measure and a jack.
Here¹s how to do it...
Preparing
1. Put the car on level ground * dead level * this is critical * you may
have to pack one or two wheels to achieve this. The two measuring points
don¹t have to be level but you must know how much they are out from each
other so you can add/subtract that amount when taking measurements (more on
this in a minute)
2. Set the ride height you want for the car (adjusting spring perchs torsion
bars up or down etc)
3. Pick two points on opposite sides of the car that you know are level
(Being a race car mines well measured up and with bits not found on std cars
that I use to measure from) * you could use each end of the steering rack
(if you¹re sure its level with the car) or bolts where the A arms attach
toward the rear (rack end) of the car (* if you¹re sure the car isn¹t bent *
if it is, a decent corner weight will be damn hard what ever method you use)
or any other points that work for you that are level. I think for Porsches
around the rack area is best since there are lots of strong points that you
can be reasonably sure arn¹t bent and it is close to the middle (front to
back) of the car (desirable * but not critical)
Its also an idea, if its a track car, to fill with the amount of fuel you
normally use and to put the drivers weight equivalent in the front seat
(doing this actually leads to my car sitting slightly up on the drivers side
when I¹m not in it and sitting level only when I am in it * but its v light
<940kgs)
Measuring
3. Starting with the front weights. Jack the rear of the car up so the rear
tyres are just off the floor * measure vertically down to the ground from
your two measuring points * if there is a difference in the distance between
the floor and each measuring point drop the car off the jack at the rear and
jack up the front and adjust the spring perches (or torsion bars) so that
the distance between the floor and each measuring point is the same * you¹ve
now balanced the front .
I usually adjust the spring that is going to bring the ride height down (but
again its a race car) - after each adjustment roll the car backwards and
forwards to settle the suspension. When getting close to level I even leave
the car for half an hour or so as it will usually settle even more (one or
two mm) - ultimately this is the difference between very good corner weight
and an adequate one (whether using this method or scales). You have
finished the front when there is no difference (or at worst one or two
millimetres difference between the two measuring points and the ground)
4. Rear weights. Jack up the front of the car so the wheels just clear the
ground. Measure vertically down from the same two measuring points* if
there is a difference in length drop the car off the jack at the front, jack
up the rear and adjust the spring perches (or torsion bars). Again you are
looking to get the distance between each measuring point and the floor the
same or within one or two mm
The first time you do this will take quite a few hours (just like doing your
first alignment) but its pretty fast once you get the hang if it. In some
respects faster than using scales since you don¹t get sucked in to chasing
weight around the car.
Accuracy
When I heard of this technique I was pretty sceptical * its too simplistic *
I learnt it from a guy who is highly regarded for his ability to set up race
and tarmac rally cars (and his ability to drive them) hes been doing it like
this for 20 years. The first few times I used this method I immediately put
the car on the scales to check * contrary to my expectations * I had the
best corner weights I¹ve ever achieved including the cross weights.
Not being the sharpest tool in the tool shed its taken me awhile to figure
why it works so well but I¹ll leave that to list conjecture. Suffice to say
there are still plenty of sceptics out there and you can help your race
budget with a few bets here and there (every little bit helps)
11-04-2005, 11:01 AM
#6
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Originally Posted by C4Russ
Springer, I'm with you right to the point of opening the valve in the hose line. Do you have the 964--- PN please? I'm going to order one tomorrow. I hope Sunset has this one in stock.
The valve is an Ace hardware fuel shut-off ball valve. The hose is 1/4" rubber fuel hose, and I used barb fittings with a hose clamp to connect to the valve. I also have an air flow meter in the line to observe directing and rate of flow when the tires are loaded. The adapters for the schraeder valve are also available at Ace.
You could also use the poly tubing and valves used for the water line to a refrigerator ice maker. I is going to be three months or so before I have a garage again. The 964 is in dry storage until then, and I can't take on any projects until my new place is ready.
I probably spent $100 on materials, and hours of time. It really would be cheaper to find a shop that does this with scales, and pay them to do it. This would be a good method if you can't locate a shop within driving distance.
11-04-2005, 11:36 AM
#7
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Originally Posted by JasonAndreas
....corner balancing without scales. I haven't tried it but I'd be curious to know if Springer (or anyone else) could debunk it?
Corner height is not the same as corner balance. Every car has variation in the suspension mounting points from manufacturing tolerances, wear, and damage. A 1/4 inch discrepancy in corner height is actually a very straight car. A quarter-inch difference will upset the corner balance by 200 lb if your spring rate is 800 lb/inch.
The method I am attempting does sense the corner balance by balancing the tire pressure with the tires in the air, and then observing the change in pressure balance when the tires are on the ground and supporting the car. Therefore it will corner balance a car that has uneven corner height (and they all do).
I tried this once already and had two problems. One is the flatness for most floors is off by more than 1/4 inch. The second is that the suspension gets side-loaded as the car is lowered. It is a problem to roll the car around and settle the suspension with all the tubing connected to the tires. Driving onto a set of scales will probably work just a little better simply because you don't upset the suspension by raising and lower the car several times during the procedure.
Has anyone used scales for corner balance, and then measured corner heights? You will know directly how straight your car is. Garrett?
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11-04-2005, 05:01 PM
#8
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Wow this sounds all too complicated. I just use a set of Longacre scales 
Interesting methods though...
To the original poster for this thread, I do not have the diameters handy, but you can get some spanners from your local Bilstein distributor. They are pretty cheap. Also here is a site on corner balancing
http://www.elephantracing.com/techto...nerbalance.htm
Interesting methods though...To the original poster for this thread, I do not have the diameters handy, but you can get some spanners from your local Bilstein distributor. They are pretty cheap. Also here is a site on corner balancing
http://www.elephantracing.com/techto...nerbalance.htm
11-04-2005, 05:52 PM
#11
Burning Brakes
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Springer3,
I really, really thought the air exchange from tire to tire thingee, process you outlined was done tongue in cheek. Hence my silly request for a PN.
Seriously, I don't see how your proposed method could easily be repeated or be even remotely accurate. There are time proven methods to corner balancing and weighting, I'll stick with those IF I chose to do this is a street car. I don't think you'll find many people who believe the extra fuss is even worthwhile.
I really, really thought the air exchange from tire to tire thingee, process you outlined was done tongue in cheek. Hence my silly request for a PN.
Seriously, I don't see how your proposed method could easily be repeated or be even remotely accurate. There are time proven methods to corner balancing and weighting, I'll stick with those IF I chose to do this is a street car. I don't think you'll find many people who believe the extra fuss is even worthwhile.
11-04-2005, 07:21 PM
#12
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Hi Jim. Yep it looks like I will be setting up shop somewhere here. Was looking at some other options with some existing places, but it didn't work out.
If I come up for Christmas Jason, I'll bring the scales with me. I'll tell my wife that it is for properly weighing the turkey (or some members of the family 
).
If I come up for Christmas Jason, I'll bring the scales with me.
I'll tell my wife that it is for properly weighing the turkey (or some members of the family ).
11-06-2005, 01:55 PM
#13
Racer
Thread Starter
thanks for the replies. I actually got the answer I needed of another forum. For those that might need to know the size is 80/90 and Gedore manufacture a nice spanner.
As enterprising as the corner weight methods go I was looking towards more conventional methods. Has anyone tried the Ruggle'Scales that use a fulcrum and "normal scales". I reckon I could fab up something similar. Anyone tell me why they should'nt work?
As enterprising as the corner weight methods go I was looking towards more conventional methods. Has anyone tried the Ruggle'Scales that use a fulcrum and "normal scales". I reckon I could fab up something similar. Anyone tell me why they should'nt work?
