brake bias bar
- Thread starter chuck 1
- Start date
My car P2125 as delivered by Olthoff has a threaded bias rod. Rod ends are threaded. Two spacer guide bushes on either side of pedal bore keep the bias rod horizontal and by means of two fingers keep the bias rod to rod ends positioned. Bias rod is lock nutted as well as each master push rod being lock nutted to the rod ends.
Seems like a well thought out and implemented arrangement to me (look at Lynns pic above for pictorial)
Obviously dealer or previous owner mucked up Chuck's assembly!
Steve
Seems like a well thought out and implemented arrangement to me (look at Lynns pic above for pictorial)
Obviously dealer or previous owner mucked up Chuck's assembly!
Steve
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If the rod end balls are threaded onto the bias bar then they must also be pinned into the rod end in such fashion that they can swivel but not rotate in order for adjustment to take place------- is this the case?
Jac Mac
The photo Jimmy Mac posted is the way it should be done.
With the proviso as Jac Mac mentioned that both threads on the bar are RHT. Although, in the photo, the clevises should be sitting closer to the pedal sleeve so that in the event of failure of one system both clevises will lock up solid against the sleeve. If you don't do it that way the bias bar will twist excessively and your pedal is likely to go to the floor before it can activate the good cylinder. A clearance of about .025" on each side is all that is required to achieve that.
It's supposed to be a fail safe as well as a balance system! Why change a proven system?? It's not difficult to make as per original!
With the proviso as Jac Mac mentioned that both threads on the bar are RHT. Although, in the photo, the clevises should be sitting closer to the pedal sleeve so that in the event of failure of one system both clevises will lock up solid against the sleeve. If you don't do it that way the bias bar will twist excessively and your pedal is likely to go to the floor before it can activate the good cylinder. A clearance of about .025" on each side is all that is required to achieve that.
It's supposed to be a fail safe as well as a balance system! Why change a proven system?? It's not difficult to make as per original!
Steve, hope the attached dwg helps. The basic problem is that when you turn the balance bar to adjust the bias the 'balls' of the rod end in each Master Cyl push rod must be prevented from turning in the rod end if the thread is cut directly into the rod end bore. For Lynns setup to work correctly the rod ends would be fitted to the 'washers with prongs' which would have the thread cut in the center bore of them-not the rod end- however I see no evidence of this. Also Lynns washers appear to have a recess that fits over the bias bar sleeve on the pedal itself. If this is the case it may act as a safety or travel limiter in a more positive manner than the example Russ has just posted of allowing a space of around 0.025"
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Not sure about those washers, I'm a bit lost on those but you don't want to limit travel too much as you need to cater for possible different working strokes on each cylinder for a whole host of different reasons under normal or race usage. Note that it is possible to lock the system up solid by closing the gap down to zero. Then you have no bias and no balance. Not desirable. There has to be a degree of movement in the system.
It all seems to be a complicated and possibly dangerous attempt to achieve something that in the originals was essentially simple, proven, and safe!
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Jac,
Thanks for explination above, understood.
I don't have my car here but if no other SPF owner or dealer responds to questions I will when my car is back home.
In meantime: I believe the rod end bearings are in fact slot pinned to the rod end (see pics from Chuck and Lynn in their posts above) and note the "bump" on rod end housing facing rear, looks like a pin head to me), also I believe the "washers" are not collared over the bias bar pedal sleeve but in fact that there is a brass bush in the sleeve and the washers float independant (OD of bush vs ID of pedal bar sleeve allows required float). I recall my inspection of the assembly in my car to have shown a slight space to allow the bias bar to pivot as required fore to aft but, the SPF design does a good job of keeping the bar in a narrow horizontal range...Also as noted if one of the masters fail the design greatly minimizes a droop in the bar that would restrict stroke.
Anyone else?
Steve
Thanks for explination above, understood.
I don't have my car here but if no other SPF owner or dealer responds to questions I will when my car is back home.
In meantime: I believe the rod end bearings are in fact slot pinned to the rod end (see pics from Chuck and Lynn in their posts above) and note the "bump" on rod end housing facing rear, looks like a pin head to me), also I believe the "washers" are not collared over the bias bar pedal sleeve but in fact that there is a brass bush in the sleeve and the washers float independant (OD of bush vs ID of pedal bar sleeve allows required float). I recall my inspection of the assembly in my car to have shown a slight space to allow the bias bar to pivot as required fore to aft but, the SPF design does a good job of keeping the bar in a narrow horizontal range...Also as noted if one of the masters fail the design greatly minimizes a droop in the bar that would restrict stroke.
Anyone else?
Steve
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Jac Mac is correct. Please have a look at the attached pictures. We source the balance bar assembly from a company called Howe Racing Enterprises. These guys build ASA race cars and use these balance bars in their cars. The rod ends are in fact pinned and threaded.
Attachments
Hi- tech, do you think you could hook me up with the needed parts to make my set up safe? or let me know where I can find the spacers, I will gladly pay for them; thanks; chuck smith
they are not on the Howe racing website ,nor is the above part
they are not on the Howe racing website ,nor is the above part
Pat Buckley
GT40s Supporter
Chuck -
Could you just have your heims threaded and pinned?
Could you just have your heims threaded and pinned?
that is correct, I have the above set up from Howe, just no spacers. Dennis Olthoff said he can put them on for me. Interestingly , he does not think they are needed ands does not have them on his car. I will fell better with them.
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