Track rod ends & hub question
Discussion
I own a modified MK6 Fiesta and i'm looking at eliminating the bump steer.
I've been given a prototype kit by a company I trust which i'll install, run and report back on. The kit was originally designed for their Astra track car so some things will obviously need to be altered.
There is however a slight issue in that the kit comes with M12 rose joints but the hub is a tapered M10 fitting so i've got two options, drill the hole to M12 and use spacers to level the steering arm or have a 'pin' made up that will bolt through the M12 rose joint, set the steering arm at the right height and then shrink down to M10 with the corresponding taper on the end for the hub.
The company that supplied the kit suggests drilling the hub to M12 and having it re-tapered while a friend who works at Ford says that a pin is the best choice and although I can drill the hub it's down to the taper which is the key element as it makes the whole link a lot stronger than a simple bolt through affair.
On the other hand i've got a friend (who I also trust fully) who runs a dedicated track day Fiesta who has simply drilled his hub to M12 and used spacers and has had no issues in 2 years of hard driving including the odd knock as you would expect for a track day car. There's also a company in the USA who makes both types of kit for a Mustang and stats this about the bolt through kit with no taper:-
[quote]Stronger and more rigid than tapered-stud style.
[/quote]
Something that originally looked so simple is starting to get me confused as to which route I should take. I've drilled the caliper mounting holes on my hubs already from M10 to M12 in order to fit the larger ST170 caliper so drilling the hub doesn''t bother me. It's all this you do/don't need a taper which is confusing.
The car is a daily driver and i'm fairly competent with spanners so if I had to replace the M12 bolt every year during a service to prevent any 'bending' of the bolt then that isn't an issue. The bolt will be a 12.9 HT cap socket along with a 1030MPa titanium nyloc washer nut at the other end, the rose joints are rated at 48KN but have been proven to take 98KN.
As you can imagine what I don't want is to do something that will effect the safety of the car, loosing steering going down the motorway isn't something that I ever want to happen so I want to do this right.
Has anyone had any experience of doing this?
I've been given a prototype kit by a company I trust which i'll install, run and report back on. The kit was originally designed for their Astra track car so some things will obviously need to be altered.
There is however a slight issue in that the kit comes with M12 rose joints but the hub is a tapered M10 fitting so i've got two options, drill the hole to M12 and use spacers to level the steering arm or have a 'pin' made up that will bolt through the M12 rose joint, set the steering arm at the right height and then shrink down to M10 with the corresponding taper on the end for the hub.
The company that supplied the kit suggests drilling the hub to M12 and having it re-tapered while a friend who works at Ford says that a pin is the best choice and although I can drill the hub it's down to the taper which is the key element as it makes the whole link a lot stronger than a simple bolt through affair.
On the other hand i've got a friend (who I also trust fully) who runs a dedicated track day Fiesta who has simply drilled his hub to M12 and used spacers and has had no issues in 2 years of hard driving including the odd knock as you would expect for a track day car. There's also a company in the USA who makes both types of kit for a Mustang and stats this about the bolt through kit with no taper:-
[quote]Stronger and more rigid than tapered-stud style.
[/quote]
Something that originally looked so simple is starting to get me confused as to which route I should take. I've drilled the caliper mounting holes on my hubs already from M10 to M12 in order to fit the larger ST170 caliper so drilling the hub doesn''t bother me. It's all this you do/don't need a taper which is confusing.
The car is a daily driver and i'm fairly competent with spanners so if I had to replace the M12 bolt every year during a service to prevent any 'bending' of the bolt then that isn't an issue. The bolt will be a 12.9 HT cap socket along with a 1030MPa titanium nyloc washer nut at the other end, the rose joints are rated at 48KN but have been proven to take 98KN.
As you can imagine what I don't want is to do something that will effect the safety of the car, loosing steering going down the motorway isn't something that I ever want to happen so I want to do this right.
Has anyone had any experience of doing this?
PaulKemp said:
If the bump steer is caused by a low rack then just space up the rack and leave the fancy track rod ends alone
The other cause of bump steer can be wrong length drum sticks on the rack
This is a much more complicated job to fix
"Just" spacing up the rack could well be a whole lot of work, and may even require engine out to get sufficient access.The other cause of bump steer can be wrong length drum sticks on the rack
This is a much more complicated job to fix
The length of the "drum sticks" i.e. track rods/tie rods is completely defined by the length of the rack and the distance between the steering arms, it's not something you can change arbitrarily. The length of the rack itself is the important factor as this fixes the location of the inner balljoints.
Regarding the OP's problem, I would prefer to use tapered pins to mate the rod ends to the steering arms. If the experiment is not successful you then have no problems getting back to the standard set-up without having to buy new parts. Drilling out would be ok, but you will need to get very tight clearances on the holes.
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