Happy Hollidays everyone!
Just a quick question:
Is the Pantera steering rack unique to the Pantera or does any other car use the same rack? (Just curious).
Thanks,
Steve
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i have a really vague feeling that it might be from a mini, but i could be totally wrong!!
Same rack, or a very similar rack, is also in the Ferrari 308.
...same crappy plastic bushing too.
Dave
...same crappy plastic bushing too.
Dave
Rack is made by Fiat
The rack is made by Cam Gears.
They had manufacturing facilities in Europe, UK & Australia supplying the automotive industry with components in the 1970’s.
They made racks for Ford, (Cortina, Escort etc) BMC, (Mini’s) & others.
I was recently talking to Johnny Woods about suitable RHD racks for the Pantera as I figured being in the UK he may have found a suitable RHD rack to do conversions.
He commented that it is in fact a rack that was also used in the 308 Ferrari & to avoid using it if possible as it’s badly designed & has a short life.
I will be hunting through wrecking yards soon to try & find a suitable replacement of similar ratio.
A slightly shorter rack will help cure the bump steer.
If you run a line between top & bottom suspension arm pivot points, the rack end ball-joint centre should intersect this theoretical line.
Currently the rack end ball joint is approx 30mm outboard of this intersection point.
This causes the wheels to steer with suspension travel, (bump steer).
Regards,
Tony.
They had manufacturing facilities in Europe, UK & Australia supplying the automotive industry with components in the 1970’s.
They made racks for Ford, (Cortina, Escort etc) BMC, (Mini’s) & others.
I was recently talking to Johnny Woods about suitable RHD racks for the Pantera as I figured being in the UK he may have found a suitable RHD rack to do conversions.
He commented that it is in fact a rack that was also used in the 308 Ferrari & to avoid using it if possible as it’s badly designed & has a short life.
I will be hunting through wrecking yards soon to try & find a suitable replacement of similar ratio.
A slightly shorter rack will help cure the bump steer.
If you run a line between top & bottom suspension arm pivot points, the rack end ball-joint centre should intersect this theoretical line.
Currently the rack end ball joint is approx 30mm outboard of this intersection point.
This causes the wheels to steer with suspension travel, (bump steer).
Regards,
Tony.
Tony what about an MGB rack? The RHD racks are available through vendors. I suggest MGB because the length could be easily extended simply because the ball can be removed for welding.
This kind of mod would allow you to completely fix bump steer:
Power steering rack setting bump steer at ZERO:
http://www.rc-tech.net/pantera1/index.htm
Here is a Pantera Rack in the middle, the MGB rack on bottom, and the power MGB conversion rack on top:
I extended the end but left it adjustable till I found the Zero bump steer point...then welded it in place. Since MGB joints are rebuild able it makes it possible to pull apart and weld without damaging the joint:
This kind of mod would allow you to completely fix bump steer:
Power steering rack setting bump steer at ZERO:
http://www.rc-tech.net/pantera1/index.htm
Here is a Pantera Rack in the middle, the MGB rack on bottom, and the power MGB conversion rack on top:
I extended the end but left it adjustable till I found the Zero bump steer point...then welded it in place. Since MGB joints are rebuild able it makes it possible to pull apart and weld without damaging the joint:
Interesting Comp2.
Can you wind the racks from lock to lock & check the number of turns of the input shaft relative to when the rack bottoms out at either end.
Also total stroke comparison between the Pantera & MGB rack.
The Pantera rack installed is around 2 7/8 turns lock to lock.
Interesting to note that the Pantera does not have a steering stop, just utilises the rack bottoming out on its stroke.
Electric over hydraulic steering, hmmmm interesting.
regards,
Tony.
Can you wind the racks from lock to lock & check the number of turns of the input shaft relative to when the rack bottoms out at either end.
Also total stroke comparison between the Pantera & MGB rack.
The Pantera rack installed is around 2 7/8 turns lock to lock.
Interesting to note that the Pantera does not have a steering stop, just utilises the rack bottoming out on its stroke.
Electric over hydraulic steering, hmmmm interesting.
regards,
Tony.
Toney, I have notes of that...somewhere...But easier yet, I will just re-measure that in the next couple days. I will get back to you with that.
Comp2, would the combination of longer control arms and wheels with higher offset have the same effect, with regard to bump-steer, as a shorter steering rack?
I don't think so because their relative position to the pivoting areas are still the same.
You would have to change your actual pivot point on the upright relative to the vertical axis to actually change the reference.
You would have to change your actual pivot point on the upright relative to the vertical axis to actually change the reference.
Comp2, do you use an early model 1963-80 MGB rack or a later model? The body of the early model measures 17 1/4". Thanks
David.
Bump steer is caused by the wheels toeing in or out during suspension travel.
To eliminate bump steer it’s more to do with the rack & pinion mounting position & its length.
Increasing both top & bottom suspension arm length & compensating by offsetting the rim further inward will decrease the negative effects of scrub radius where the steering wheel tends to “kick” when the outside edge of the wheel hits a bump.
So effectively what you are doing here is decreasing the distance between the outside edge of the wheel & the steering axis, (the top & bottom ball joints that the wheel pivots upon).
Another way of decreasing the scrub radius is to have a longer lower suspension arm, combined with a suspension upright with a different stub axle angle.
Example:
If you fitted a longer lower arm the wheel would go into severe positive camber, (top of the wheel leaning in).
To compensate the best way is to fit a new upright which brings the axle back to horizontal to the ground.
If you draw a line between the top & bottom ball joints & where that line intersects the ground the ideal intersection point is the centre of the tyres contact patch.
So the wheel/tyre pivots on the centre of its own axis.
The problem with the Pantera steering is that intersection point is a long way inboard of the wheels centre.
Fitting wider front wheels that are widened further outward exacerbate the problem.
Regards,
Tony.
Bump steer is caused by the wheels toeing in or out during suspension travel.
To eliminate bump steer it’s more to do with the rack & pinion mounting position & its length.
Increasing both top & bottom suspension arm length & compensating by offsetting the rim further inward will decrease the negative effects of scrub radius where the steering wheel tends to “kick” when the outside edge of the wheel hits a bump.
So effectively what you are doing here is decreasing the distance between the outside edge of the wheel & the steering axis, (the top & bottom ball joints that the wheel pivots upon).
Another way of decreasing the scrub radius is to have a longer lower suspension arm, combined with a suspension upright with a different stub axle angle.
Example:
If you fitted a longer lower arm the wheel would go into severe positive camber, (top of the wheel leaning in).
To compensate the best way is to fit a new upright which brings the axle back to horizontal to the ground.
If you draw a line between the top & bottom ball joints & where that line intersects the ground the ideal intersection point is the centre of the tyres contact patch.
So the wheel/tyre pivots on the centre of its own axis.
The problem with the Pantera steering is that intersection point is a long way inboard of the wheels centre.
Fitting wider front wheels that are widened further outward exacerbate the problem.
Regards,
Tony.
quote:Originally posted by Edge:
Interesting Comp2.
Can you wind the racks from lock to lock & check the number of turns of the input shaft relative to when the rack bottoms out at either end.
Also total stroke comparison between the Pantera & MGB rack.
The Pantera rack installed is around 2 7/8 turns lock to lock.
Interesting to note that the Pantera does not have a steering stop, just utilises the rack bottoming out on its stroke.
Electric over hydraulic steering, hmmmm interesting.
regards,
Tony.
Tony I measured the two racks yesterday. I had done this before but it has been a long time and I had forgotten the details.
The Pantera Rack:
1 turn = 1.5"
3.25 turns total
4.874" total movement
The MG Rack:
1 turn = 2 7/32"
3 turns
6.625" Total movement
This makes the MG rack a bit too coarse for the Pantera. I am still looking for my notes but the Power rack from MGOC was a lot closer in the ratio.