Vixen bump steer
Discussion
Has anyone successfully eliminated bump steer from their Vixen? I am thinking about relocating the steering rack on my S3 in an effort to improve it and rather than trial and error, was hoping that someone else has already done it and can give me some guidance. It looks like it needs remounting roughly 20mm higher than current. Any advice appreciated.
Lower, Lower!
There are various schools of thought for this and the more people I talk to the more confused I get.
The steering shaft is very long and wobbly and some builders have fitted a hook joint to the chassis to keep the shaft from vibrating, this mod certainly won't do any harm.
Some very very clever people out there, Such as Trevor Jasper and Darren Evans (Are you watching boys) need to share their secrets a little more!! Hint Hint,
C'mon lads, you are enthusiasts you shouldn't be so secretive.
Adrian? You know that this mod needs to happen to 3 of my vehicles, What do you think the best way forward is??
Neil.
There are various schools of thought for this and the more people I talk to the more confused I get.
The steering shaft is very long and wobbly and some builders have fitted a hook joint to the chassis to keep the shaft from vibrating, this mod certainly won't do any harm.
Some very very clever people out there, Such as Trevor Jasper and Darren Evans (Are you watching boys) need to share their secrets a little more!! Hint Hint,
C'mon lads, you are enthusiasts you shouldn't be so secretive.
Adrian? You know that this mod needs to happen to 3 of my vehicles, What do you think the best way forward is??
Neil.
SHORTER, SHORTER!
BUT I ony have ONE shortend rack bar left Neil.......
There are no secrets.
This is a car's steering you are talking about ...You can't just gift things like this away esp. when you never know who going to cut and chop a rack bar without thinking about the engineering of a 100% joint through.
Adrian
BUT I ony have ONE shortend rack bar left Neil.......
There are no secrets.
This is a car's steering you are talking about ...You can't just gift things like this away esp. when you never know who going to cut and chop a rack bar without thinking about the engineering of a 100% joint through.
Adrian
Neil, Do you know that lower is the solution and if so, have you tested it? How much lower? I'd be surprised - it definitely looks like it needs to be higher to me!
Adrian, When you say shorter rack bar are you referring to shorter steering arms? I can see that this might help but presumably a wider rack is needed to reposition the ball joint of the steering arm closer to the suspension upright?
Thanks,
Tom
Adrian, When you say shorter rack bar are you referring to shorter steering arms? I can see that this might help but presumably a wider rack is needed to reposition the ball joint of the steering arm closer to the suspension upright?
Thanks,
Tom
The shoter rack body brings the arms into the correct arc (well, a better arc than original) you need a extension M/F for one arm and different arm for the other as well as a modified mounting set up for the chassis along with the shortened rack body (the vision is to bring all the 3 arcs of the upper, lower wishbones and rack to a inherently happy position at ride height in very simple terms)
Adrian@
Adrian@
Edited by adrian@ on Tuesday 19th September 10:09
Thanks Adrian. I understand what needs to be achieved and was trying to work out the best option to get there. A modified rack sounds fine in principle but a bit of a pain in practice. If I could get 50% of the improvement that a modded rack would give but with 10% of the effort i.e. by raising or lowering it then I would be happy with that.
If I had to go down the modified rack route, do you know if it repositions the shaft i.e. have to find a different route through the chassis?
Thanks,
Tom
If I had to go down the modified rack route, do you know if it repositions the shaft i.e. have to find a different route through the chassis?
Thanks,
Tom
There is no problem with the column shaft, for road going I personally do not think that any changes than optimizing the current set up, replacing the rubber version of the column joint, poly bushes and looking at getting a good set of soft wall tech tyres that give some compliance having tightened up every other part (the racing boys have age related changes of upright and trunnion with kits and a rose jointed version of the top ball joint that lowers the wishbone along with the rack and chassis mounting mod)
Adrian@
That said, I don't like playing percentages, as standard this is one of the best handling cars that TVR built until the current 'T' cars that are made today.
Adrian@
That said, I don't like playing percentages, as standard this is one of the best handling cars that TVR built until the current 'T' cars that are made today.
Its a road going car - I've already got it polybushed and its running 205/60R15 Bridgestones on 7J rims. I've got the rack on solid mounts but it's still got the rubber spider type universal joint between the column and pinion shaft. I think I will do some measuring up tonight and see if I can calculate a better position for the standard rack. Then I'll see if it's actually practical to re-position it!
Cheers,
Tom
Cheers,
Tom
I am waiting for darren to pipe up here???
His car is running a rose jointed top balljoint and also a ford escort RS2000 rack??,
Again I need to read more
A very good book on the whole subject is
"How to make your car handle"
Author Fred Puhn
Published by HP Books and available mail order through the usual specialists, demon tweaks, motor books etc, etc.
The reason I say lower is my sneaky looks at other cars, Darrens is lower, Jamie boots Fia racing car is lower, most of Chris schirles racing griffs are lower?? thus lower must be for some reason, However that said I don't know what other tweaks those cars have.
Neil.
His car is running a rose jointed top balljoint and also a ford escort RS2000 rack??,
Again I need to read more
A very good book on the whole subject is
"How to make your car handle"
Author Fred Puhn
Published by HP Books and available mail order through the usual specialists, demon tweaks, motor books etc, etc.
The reason I say lower is my sneaky looks at other cars, Darrens is lower, Jamie boots Fia racing car is lower, most of Chris schirles racing griffs are lower?? thus lower must be for some reason, However that said I don't know what other tweaks those cars have.
Neil.
Neil,
That's why I pointed at a book, there are 2 ways to go...hard or soft ....the cars you mention I think run ARB's between the rack and linked to the top wishbones as a Chris S. would run, with mega poundage springs, and leaves the car solid and predictable to a race car driver, I've never gone down that route as I like to think that a normal driver is reacting to his BUM....because he's not a race car driver and has limits and some sort brain that is tuned into and related to fear! Both ways can be bloody quick.
Adrian@
That's why I pointed at a book, there are 2 ways to go...hard or soft ....the cars you mention I think run ARB's between the rack and linked to the top wishbones as a Chris S. would run, with mega poundage springs, and leaves the car solid and predictable to a race car driver, I've never gone down that route as I like to think that a normal driver is reacting to his BUM....because he's not a race car driver and has limits and some sort brain that is tuned into and related to fear! Both ways can be bloody quick.
Adrian@
adrian@ said:
Neil,
That's why I pointed at a book, there are 2 ways to go...hard or soft ....the cars you mention I think run ARB's between the rack and linked to the top wishbones as a Chris S. would run, with mega poundage springs, and leaves the car solid and predictable to a race car driver, I've never gone down that route as I like to think that a normal driver is reacting to his BUM....because he's not a race car driver and has limits and some sort brain that is tuned into and related to fear! Both ways can be bloody quick.
Adrian@
That's why I pointed at a book, there are 2 ways to go...hard or soft ....the cars you mention I think run ARB's between the rack and linked to the top wishbones as a Chris S. would run, with mega poundage springs, and leaves the car solid and predictable to a race car driver, I've never gone down that route as I like to think that a normal driver is reacting to his BUM....because he's not a race car driver and has limits and some sort brain that is tuned into and related to fear! Both ways can be bloody quick.
Adrian@
As opposed to us race car builders with BUM in Brain and no fear
Neil.
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