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upright with rear steering arm
8smokingbarrels - 14/7/03 at 06:42 PM

Anyone know cars whose uprights have their steering arms towards the rear? I think some MR2's do- being mid-engined means its probably easier to fit the rack behind the front axle. But was just wondering if there was anything a bit more mainstream (i.e. easier to get at the local scrappie! )


chris

Noodle - 14/7/03 at 06:44 PM

X1/9's do. And Morris Minors (if you don't mind trunnions)

I'm about to butcher my semi-dissolved X1/9 for a project. There are loads of defunct one's about.

Cheers,

Neil.

theconrodkid - 14/7/03 at 07:36 PM

mk3 on escorts and fiesta,mondeo are prob fave

8smokingbarrels - 15/7/03 at 11:32 PM

Thx guys for the replies

The ford stuff sounds v.interesting. Id checked a sierra but it was front mounted. Should be no probs getting hold of either fiesta, escort or mondeo

thx again

chris

ChrisW - 16/7/03 at 07:39 AM

Agreed - Most of the FWD Ford stuff runs the rack behind the front axle.

Chris

andyps - 18/7/03 at 10:20 AM

Is there a problem with running the uprights on the wrong sides to get the steering arm in the right place? I know that this could affect castor angle etc. but assuming this can be corrected I cannot think of any reason why this wouldn't work, but I'm not clever on suspension - yet!

Findlay234 - 18/7/03 at 11:07 AM

If you want some mk1 mr2 uprights with a steering rack, track rod ends, most of the column, etc just give us a shout! Ive got an mr2 on the drive growing mould. It was gonna be my engine donor, ill still keep the engine for a while though.

8smokingbarrels - 18/7/03 at 07:21 PM

Andy, yeah you are right- swapping uprights is going to mess up your castor. Put simply- the upper balljoint must be further towards the rear of the car than the lower bj. (Positive Castor)

As I see it swapping the uprights would make the upper balljoint further FORWARDS creating what I think is known as NEGATIVE castor which is dangerous. The reason for this is that, at rest, the outside wheel adopts positive camber when turned, which of course becomes much worse when actually driving the car round a corner!

BTW Des Hammill's book is great for explaining all this suspension stuff. Its quite short which is great if u prefer welding to reading!!

chris

leto - 18/7/03 at 07:41 PM

quote:
Originally posted by andyps
Is there a problem with running the uprights on the wrong sides to get the steering arm in the right place? I know that this could affect castor angle etc. but assuming this can be corrected I cannot think of any reason why this wouldn't work, but I'm not clever on suspension - yet!


There is this guy named Ackerman, he has an angle on that.....(And the ref. gives a 2 min penalty for foul punning).

Steering geometry will be somewhat odd. My guess is, you will get more understeer the harder you try to corner. But I'm not that clever on suspension either, yet
Try your search engine for "Ackerman Steering" and "Ackerman Angle"

Also brakes might be designed to withstand loads better in one direction

leto

[Edited on 18/7/03 by leto]

leto - 18/7/03 at 08:13 PM

quote:
Originally posted by 8smokingbarrels
Andy, yeah you are right- swapping uprights is going to mess up your castor. Put simply- the upper balljoint must be further towards the rear of the car than the lower bj. (Positive Castor)
.................

chris


OK, so I am a bit finicky to night, must be the heat.
Switching only uprights will not affect the castor angle. The castor angel is created by arms and struts and such. On a locost you can get negative castor by turning the upper a-arm upside down. Anyone tried that?

leto

leto - 19/7/03 at 06:51 AM

quote:
Originally posted by gazza285
Don't worry about Akermann, Colin Chapman didn't. Most Lotus cars have (had?) parallel steering arms as He though that Akermann with radial tyres was a waste of time.


I agree that it isn't a big issue as long as you keep the Ackerman angle behind you. But if you get it in front of you performance will suffer. Here in Sweden you will not get an approval if the Ackerman angle is in front of the car.
Happy building.
Leif