fbekholden.com

Thought I'd post this here, as I've been going over and over it and think I have it right, if I havnt please comment or happy to give out my number to talk on the phone, only new at all this,

Now what I've worked out:
A= 1450mm
B= 20mm
C= 145mm
D= 205mm

So the rims I have are 7" interceptors, with 225 tyres I'm going to have 20mm space inside and outside of tyre and car, which is what B stands for

I'm open to suggestions, ideas, things I havnt thought of
If I had hair I would have pulled it out by now

So what do you need to know , how much to narrow the diff ? I dummied mine up , fitted the rims less tyres then measured from there. Took about 120mmmm out from memory , about as much as you could without the calipers hitting the springs.

Yeah sorry mate, how much to narrow it, I worked it out to be 100mm but that's only going by measurements not trial fitting,

I think the way I would work it out is to have the old rear end out of the car, get the wheels and tyres sitting in the wheel well and measure between the two inner faces of the wheels (where they bolt on).

What size side wall are you having with the 225 tyres?
The reason I ask is I had 215/75/14 on the wagon and had to pump out the inner guards for clearance, because of the tall (75) side wall they bulged out past the 215 tread width witch made them rub.
I did have a 225/60/14 spare tyre on it and it was spot on .

Tyres will be 225x60x15, havnt got tyres yet will get them this week, I'll also take the diff out and put rims and tyres in as you said, see if it works out the same as I measured, cheers guys

Yep my measurements were spot on, diff goes in tomorrow to be shortened

Trev wrote:I think the way I would work it out is to have the old rear end out of the car, get the wheels and tyres sitting in the wheel well and measure between the two inner faces of the wheels (where they bolt on).

What size side wall are you having with the 225 tyres?
The reason I ask is I had 215/75/14 on the wagon and had to pump out the inner guards for clearance, because of the tall (75) side wall they bulged out past the 215 tread width witch made them rub.
I did have a 225/60/14 spare tyre on it and it was spot on .

I'm a bit out of my depth here, but 20mm doesn't seem like a lot of clearance for a live rear end, bulge or no bulge in the sidewall. I admit that there's a fair bit of science that I don't understand about rear suspension & diffs, but I'd be concerned that when the wheel on one side drops lower than the other, the wheel on the opposite side will pivot inwards at the top and outwards at the bottom. I don't think it would take much of a pothole to push the inside top of the opposite tyre into the guard.

MeFB wrote:

Trev wrote:I think the way I would work it out is to have the old rear end out of the car, get the wheels and tyres sitting in the wheel well and measure between the two inner faces of the wheels (where they bolt on).

What size side wall are you having with the 225 tyres?
The reason I ask is I had 215/75/14 on the wagon and had to pump out the inner guards for clearance, because of the tall (75) side wall they bulged out past the 215 tread width witch made them rub.
I did have a 225/60/14 spare tyre on it and it was spot on .

I'm a bit out of my depth here, but 20mm doesn't seem like a lot of clearance for a live rear end, bulge or no bulge in the sidewall. I admit that there's a fair bit of science that I don't understand about rear suspension & diffs, but I'd be concerned that when the wheel on one side drops lower than the other, the wheel on the opposite side will pivot inwards at the top and outwards at the bottom. I don't think it would take much of a pothole to push the inside top of the opposite tyre into the guard.

Like this...

[quote="MeFB"][quote="MeFB"][quote="Trev"]I think the way I would work it out is to have the old rear end out of the car, get the wheels and tyres
I'm a bit out of my depth here, but 20mm doesn't seem like a lot of clearance for a live rear end, bulge or no bulge in the sidewall. I admit that there's a fair bit of science that I don't understand about rear suspension & diffs, but I'd be concerned that when the wheel on one side drops lower than the other, the wheel on the opposite side will pivot inwards at the top and outwards at the bottom. I don't think it would take much of a pothole to push the inside top of the opposite tyre into the guard.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>.
Allan go take a look at a rear wheel well with the tyre and rim removed ...you will notice that GMH in their wisdom have the movement you describe covered by the fact that the top of the inner wheel well slopes toward the inner centre of the car effectively giving another 20 or 30 mms of clearance when the axle reacts like you say .......Fingers

You are rite Alan, I don't have any technical knowledge why (except having it pretty low = not much suspension travel) but I never had any side wall rubbing with approx 10mm space either side of each rear wheel.
Guess it pays to lower these old girls .

fingers wrote:Allan go take a look at a rear wheel well with the tyre and rim removed ...you will notice that GMH in their wisdom have the movement you describe covered by the fact that the top of the inner wheel well slopes toward the inner centre of the car effectively giving another 20 or 30 mms of clearance when the axle reacts like you say .......Fingers

There ya go. I've never really looked close enough to notice. Thanks for that Fingers.

MeFB wrote:

MeFB wrote:

Trev wrote:I think the way I would work it out is to have the old rear end out of the car, get the wheels and tyres sitting in the wheel well and measure between the two inner faces of the wheels (where they bolt on).

What size side wall are you having with the 225 tyres?
The reason I ask is I had 215/75/14 on the wagon and had to pump out the inner guards for clearance, because of the tall (75) side wall they bulged out past the 215 tread width witch made them rub.
I did have a 225/60/14 spare tyre on it and it was spot on .

I'm a bit out of my depth here, but 20mm doesn't seem like a lot of clearance for a live rear end, bulge or no bulge in the sidewall. I admit that there's a fair bit of science that I don't understand about rear suspension & diffs, but I'd be concerned that when the wheel on one side drops lower than the other, the wheel on the opposite side will pivot inwards at the top and outwards at the bottom. I don't think it would take much of a pothole to push the inside top of the opposite tyre into the guard.

Thats when you need this -

i've had what MeFB described happen but only on pretty severe slopes such as turning into a driveway etc, would have had less than 20 mill clearance also

Got the Diff back, turns out I forgot about the rotors so the diff will be 16mm wider than I hoped for, can't believe I forgot !