I'll have to make some if I can't get hold of any.
Tie bar fork to lower suspension arm spacer needed, help!
Forum rules
By using this site, you agree to our rules. Please see: Terms of Use
By using this site, you agree to our rules. Please see: Terms of Use
-
davidwarren
- Minor Friendly
- Posts: 60
- Joined: Thu May 03, 2007 5:04 pm
- Location: Washington, Tyne & Wear
- MMOC Member: No
Tie bar fork to lower suspension arm spacer needed, help!
Hi, the tie bar fork to lower suspension arm spacers are missing from my moggie. Please help. Does anyone on this forum have any spare?
I'll have to make some if I can't get hold of any.
I'll have to make some if I can't get hold of any.
[img]http://images.fotopic.net/?id=44538713&outx=300[/img]
See my pictures at: http://davidwarren.fotopic.net/
See my pictures at: http://davidwarren.fotopic.net/
-
davidwarren
- Minor Friendly
- Posts: 60
- Joined: Thu May 03, 2007 5:04 pm
- Location: Washington, Tyne & Wear
- MMOC Member: No
Of course - assuming the trunnions are nicely greased and the tyres pumped up ~ 28 psi - then the slightly heavy steering could be because of slightly increased caster. However - I would have thought the effect would be very slight! Minor steering is normally 'finger tip' light !! Which check for stiffness - jack the front wheels off the ground - you should be easily able to swing the steering from lock to lock (don't bang it against the end stops!) by turning one wheel with your hands. If you can't do that - then something is seized.
-
davidwarren
- Minor Friendly
- Posts: 60
- Joined: Thu May 03, 2007 5:04 pm
- Location: Washington, Tyne & Wear
- MMOC Member: No
Hi, when I changed my bushes I could swing the steering when the wheels were off the ground. It took minimal effort to do.
To be honest I haven't tried the steering on another minor to compare. Mine is probably ok, I'm just worried about the spacers.
To be honest I haven't tried the steering on another minor to compare. Mine is probably ok, I'm just worried about the spacers.
[img]http://images.fotopic.net/?id=44538713&outx=300[/img]
See my pictures at: http://davidwarren.fotopic.net/
See my pictures at: http://davidwarren.fotopic.net/
The steering will be lighter not heavier with these spacers removed. Just think of it as being a chopper or any motorbike, choppers have very high angles to improve stability, where as GP racers have low angles for flickability.
The spacers are rectangular in shape to spread the load on the arm and make sure that the full width of the fork is covered.
The effect of having these spacers is very significant in upsetting all of the front end geometry, and should be replaced as soon as possible.
as BM suggests you should get the front end set up correctly, as a well set up system transforms your car.
The spacers are rectangular in shape to spread the load on the arm and make sure that the full width of the fork is covered.
The effect of having these spacers is very significant in upsetting all of the front end geometry, and should be replaced as soon as possible.
as BM suggests you should get the front end set up correctly, as a well set up system transforms your car.
Last edited by jonathon on Thu Aug 30, 2007 9:25 am, edited 2 times in total.
-
davidwarren
- Minor Friendly
- Posts: 60
- Joined: Thu May 03, 2007 5:04 pm
- Location: Washington, Tyne & Wear
- MMOC Member: No
Hi Jonathon, I've love to have them off you please. I'd be more than happy to pay for postage. Price it up and let me know. I have your e-mail address off when we were talking about seat bases. I'll send you a mail so you can get in touch. Thankyou 
[img]http://images.fotopic.net/?id=44538713&outx=300[/img]
See my pictures at: http://davidwarren.fotopic.net/
See my pictures at: http://davidwarren.fotopic.net/
J - it makes the steering HEAVIER and with more self-centering when the caster is increased - which is what will happenb without these square washers! I wasn't suggesting small round washer - but washers of the correct size to cover the fork. The loads are only tensile anyway on a Minor - when the brakes are used - the tie bar opposes the forces trying to rip the lower arm off the car. No front wheel drive compressive forces (unfortunately) on a Minor.
BM
With these spacers removed you are going to decrease the caster angle from around 4 to 1 degree. I agree increased caster,say 6 degrees will give heavier,self centering steering, hence my analogy to choppers.
Simple rule:
The greater the angle of caster, the stronger the centring force, which effectively means heavier steering. With a low caster angle the car will be more willing to go around the corners, but the counter effect is that is will be less willing to straighten up afterwards. If a car is given too much caster, i.e. the bottom of the steering axis is further forward than the top, the steering will be very heavy and the car will be reluctant to turn into a corner. Conversely, if the car were to be given negative caster, with the lower end of the axis further back than the top, there would be no directional stability at all. The car would need constant steering adjustment to keep it in a straight line.
With these spacers removed you are going to decrease the caster angle from around 4 to 1 degree. I agree increased caster,say 6 degrees will give heavier,self centering steering, hence my analogy to choppers.
Simple rule:
The greater the angle of caster, the stronger the centring force, which effectively means heavier steering. With a low caster angle the car will be more willing to go around the corners, but the counter effect is that is will be less willing to straighten up afterwards. If a car is given too much caster, i.e. the bottom of the steering axis is further forward than the top, the steering will be very heavy and the car will be reluctant to turn into a corner. Conversely, if the car were to be given negative caster, with the lower end of the axis further back than the top, there would be no directional stability at all. The car would need constant steering adjustment to keep it in a straight line.
J - with the spacers removed the wheels are being tugged FORWARDS more than before - this INCREASES the caster angle = heavier steering! I think it's a really good idea - need to check if my car has the spacers or not. More caster = more negative-on-lock which helps turn-in and cornering. Modern cars have quite a bit of caster - and power steering of course!
-
chickenjohn
- Minor Legend
- Posts: 4064
- Joined: Tue Dec 07, 2004 8:50 am
- Location: Margate, East Kent
- MMOC Member: No
BM if you remove the spacer it pulls the leg backwards,not push it forwards. The above rule explains this.
John, this might explain caster for you
The steering axis is the point around which the wheel pivots when the steering is turned. On some cars it will be around the suspension strut, on others where the upright bolts to the wishbones or front axle. In either case, it is the vertical alignment of the top and bottom of this axis that determines caster. On road cars the bottom end will be further forward than the top, giving positive caster. This creates an effect like the wheels on a shopping trolley. If it is pushed forward the wheels will centre themselves, pointing in the direction of travel. Therefore the aim with caster is to get a balance between straight-line stability and getting the car to turn easily, without too much effort from the driver. This is achieved by having different amounts of caster on each wheel. The inside wheel will have a low caster angle, though still positive. This gives the light steering into the corner. A higher amount of caster on the outside wheel will give the car the straight-line characteristics that are required.
John, this might explain caster for you
The steering axis is the point around which the wheel pivots when the steering is turned. On some cars it will be around the suspension strut, on others where the upright bolts to the wishbones or front axle. In either case, it is the vertical alignment of the top and bottom of this axis that determines caster. On road cars the bottom end will be further forward than the top, giving positive caster. This creates an effect like the wheels on a shopping trolley. If it is pushed forward the wheels will centre themselves, pointing in the direction of travel. Therefore the aim with caster is to get a balance between straight-line stability and getting the car to turn easily, without too much effort from the driver. This is achieved by having different amounts of caster on each wheel. The inside wheel will have a low caster angle, though still positive. This gives the light steering into the corner. A higher amount of caster on the outside wheel will give the car the straight-line characteristics that are required.
Okay, I give in, you are correct.
Mind ,a 5mm difference in position is equal to around 6 degrees of caster. therefore giving between 9-10 degrees positive caster, not a good idea.
Unless you use an adjustable tie bar designed for this mod you will end up crushing the tie bar bushes and put undue strain on the eyebolt bushes, let alone the top trunnion bushes. Keep it standard or as close to as possible.
High positive caster creates a more reluctant turn in, allied to heavier steering and additional stresses on bushes I'd be very wary of leaving this plate out.
Mind ,a 5mm difference in position is equal to around 6 degrees of caster. therefore giving between 9-10 degrees positive caster, not a good idea.
Unless you use an adjustable tie bar designed for this mod you will end up crushing the tie bar bushes and put undue strain on the eyebolt bushes, let alone the top trunnion bushes. Keep it standard or as close to as possible.
High positive caster creates a more reluctant turn in, allied to heavier steering and additional stresses on bushes I'd be very wary of leaving this plate out.
-
chickenjohn
- Minor Legend
- Posts: 4064
- Joined: Tue Dec 07, 2004 8:50 am
- Location: Margate, East Kent
- MMOC Member: No
Having more positive caster will increase camber on cornering, so will wear the inside of your tyre more. In a straight ahead position I'd assume little change in wear. The provisor is that you do not increase the angle too much, for a road car, especially the minor which is not designed to accomodate this degree of change.
Your 4 dr would have had heavier steering than the trav and be more reluctant to turn in, but may have had more grip in the corner once turned in. Having one spacer in and one missing would cause an interesting set up.
Most street car alignments call for the front camber and caster settings to be adjusted to slightly different specifications on the right side of the vehicle compared to the left side. These slight side-to-side differences are called cross-camber and cross-caster.
For vehicles set up to drive on the "right" side of the road, the right side is aligned with a little more negative camber (about 1/4-degree) and a little more positive caster (again, about 1/4-degree) to help the vehicle resist the influence of crowned roads that would cause it to drift "downhill" to the right gutter. Since most roads are crowned, cross-camber and cross-caster are helpful the majority of the time, however they will cause a vehicle to drift to the left on a perfectly flat road or a road that leans to the left.
Hope this helps.
Your 4 dr would have had heavier steering than the trav and be more reluctant to turn in, but may have had more grip in the corner once turned in. Having one spacer in and one missing would cause an interesting set up.
Most street car alignments call for the front camber and caster settings to be adjusted to slightly different specifications on the right side of the vehicle compared to the left side. These slight side-to-side differences are called cross-camber and cross-caster.
For vehicles set up to drive on the "right" side of the road, the right side is aligned with a little more negative camber (about 1/4-degree) and a little more positive caster (again, about 1/4-degree) to help the vehicle resist the influence of crowned roads that would cause it to drift "downhill" to the right gutter. Since most roads are crowned, cross-camber and cross-caster are helpful the majority of the time, however they will cause a vehicle to drift to the left on a perfectly flat road or a road that leans to the left.
Hope this helps.
You think the 5mm spacer will make THAT much difference to the caster ? If so - then that could explain the heavy steering on David's car. Mt experience of playing with this is on Minis - where maximum caster is wanted to get good turn-in and traction - and yes it makes the steering VERY heavy and very self centering, especially if used with dollops of -ve camber and high power engine. Not sure how effective it would be on non-driven wheels car. Next time I am playing with the suspension I will leave the spacers out - and see what happens!
Thought I ought to test my thoughts so set up the jig on the car with and without the spacer, the difference was slightly under 6 degrees. 
( note this is not a hard and fast figure, as the tie bar can induce differing levels of caster,dependent on condition of bushes and tightness of end nut.)
( note this is not a hard and fast figure, as the tie bar can induce differing levels of caster,dependent on condition of bushes and tightness of end nut.)
Last edited by jonathon on Fri Aug 31, 2007 7:42 am, edited 1 time in total.
-
davidwarren
- Minor Friendly
- Posts: 60
- Joined: Thu May 03, 2007 5:04 pm
- Location: Washington, Tyne & Wear
- MMOC Member: No
Hi, when I get my spacers off Jonathon, whats the best way to ensure the lower suspension arm is in the right place when it comes to fitting them? I assume that when I re-fit the tie bar I tighten the nut each side of the two bushes without moving the lower suspension arm. Am I right in saying with no tie bar in place the lower suspension arm is in the right place with respect to camber?
David
David
[img]http://images.fotopic.net/?id=44538713&outx=300[/img]
See my pictures at: http://davidwarren.fotopic.net/
See my pictures at: http://davidwarren.fotopic.net/
The spacers will be with you tommorow David
The only way to get the correct geometry is to measure it. The original tie bar is a means to an end rather than an actual predetermined setting. The reason for this is the play available in the bushes at the end. So consider the initial fitting as a near too then take the car to be set up correctly. With the correct equipment checking all of the angles can be achieved within an hour. Setting up correctly depends on what areas need changing ,replacing etc. Believe me its well worth the effort and cost.
The only way to get the correct geometry is to measure it. The original tie bar is a means to an end rather than an actual predetermined setting. The reason for this is the play available in the bushes at the end. So consider the initial fitting as a near too then take the car to be set up correctly. With the correct equipment checking all of the angles can be achieved within an hour. Setting up correctly depends on what areas need changing ,replacing etc. Believe me its well worth the effort and cost.