Caliper placement,in front or behind strut?

[amon]

Hey fellas,i have done the XT130/GMH(dba015)/hilux conversion on my RA28.
Now as stated in title in front or behind for the caliper?
What differences are there? They are behind at the moment and clear my steering arms just.

Any thoughts
Cheers Guy

["Z" UTE]

amon, the calipers on an XT30 strut sit at the rear, got to go that way because of the mount brackets. Swapping the struts left to right would put the calipers out front, but that would cause major dramas with the lower control arm mount, as they are slightly offset.

cheers Chuck.

[SilverRA23]

Does this apply to all cars?

I have put my C/P/H upgrade on my KE35 with the calipers at the front.

Haven't driven it in anger as yet, only around the block, but no fouling issues.

[RAAAH23]

no dont think i does make much of a difference whether they are and the front or back of the disc. depends on the struts and the car make. usually toyota have them at the rear but i have noticed other manufacturers place them at the front.

[RobertoX]

It usually comes down to packaging.
However there is also the effect of the weight of the calliper on the steeing.
As you corner the inertia of the caliper creates a torque around the steering axis.
If the caliper is front mounted the torque create a moment that steers the wheels in the opposite direction to the corner (effectively an understeer moment), and vice versa.

I'm not saying that it will make your car oversteer if you mount them at the back or anything, however there might be some difference in steering feel. I worked out the forces once and they weren't massive but they also weren't negligible.
It would be interesting to do an experiment and try both out, swap the struts side to side and see what difference there is, all you'd have to do is pull the strut out and switch over the strut tops...

[Moppitt]

Its interesting to look at F1 in this regard. Different teams have them mounted inboard (behind the front axle, in front of the rear axle), outboard (the opposite of inboard) and below the hub (caliper literally lying on its back).

I'm not sure if they use combination's of the above though. Its interesting none the less.

[RobertoX]

hmmm... usually the terminology "inboard" and "outboard" refers to whether the brakes are mounted to the sprung or unsprung mass.
For example on the rear it is common to have inboard mounted brakes where the discs are mounted straight to the stub axles coming from the diff. If someone searches for info on inboard mounted brakes they might get confused... usually just forward or rearward mounted of the axle.
You are right about F1 though, there are lots of different combinations. Its one of those things that would depend on many other factors, like packaging and the set up of the rest of the steering and suspension.

[TERRA Operative]

Jaguar XJS had inboard mounted rear calipers.

[Moppitt]

I recall that some old jags and alfas had inboard brakes in the classic sense.

Thats what initially confused me about F1 but thats the terminology they used and so I used it with the explanation of just what I was talking about.

Edit: Beaten by terra about the jag

[RobertoX]

Yeah I think that older alfa with the de'dion rear end had them... 146? can't remember, but I remember seing one and thinking "wtf, where are the brakes and the diff?"

And that's the thing with terminology, you can call something whatever you like. And with cars each component has different names depending on who you talk to and the same name is used for different things... lol


edit: I just googled the alfa and it was the GTV6... also had double wishbones on the front with torsion bars! cool

["Z" UTE]

It would be interesting to do an experiment and try both out, swap the struts side to side and see what difference there is, all you'd have to do is pull the strut out and switch over the strut tops...

Strut tops are the same on both sides of an XT 130 Corona/TA22/TA23/RA2x. However the PCD is different between the models The drama in swapping sides would be in the steering arm mounts on the strut, as they are asymetric. Swapping sides would lead to some horrendous toe out problems.


cheers Chuck.

[RobertoX]

Oh right, that is a problem. Even once you fix the toe you will have different ackermann, depending on the installation, this will affect the handling much more than the caliper weight effect.
Interesting about the strut top, I didn't know that...

Still you could do the experiment by yourself, it's not too hard to adjust toe at home acurately.

[amon]

Thanks for the input chaps.Chuck I think you might be right on the fouling and the change of steering geo, i was thinking along the lines of braking performance?better/worse?feel? from braking forces acting on a different point on the strut etc..

thanks Guy

[rob]

xt130 struts on a KE35

had to mount them this way because with the caliper at the back the brake line was kinking in a manner that i wasnt happy with when at full lock.

never had any hassle with them and was able to have wheel alignment at factory specs

[ecko]

biggest issue i think is to make sure bleed nipple is at the top of the caliper otherwise they wont bleed up right