kango
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| posted on 15/1/08 at 04:36 AM |
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Mixed axles and ET
Starting to gather all the bits for my new car and have red most of the posts on ET and off set.
The facts :-
Cortina 6.5JET19
Sierra ET 6.5J38
Using Cotina uprights and Sierra Rear IRS does it mean one has to use a 19ET on the front axle and a 38ET on the back axle.
[Seems ET and off set is the same thing]
So wanting to change to 7J up front so the ET changes to +-12 and 8J at the back so the ET changes to +-19. this is if I calculate to retain the same
backspace.
Is this what one whants to achieve when you change rim widths?
By the way the link referred to in one of the posts to do all these calculations has been removed due to too many people using it. Perhaps somebody
can recall it and put it on a new link.
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Mr Whippy
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| posted on 15/1/08 at 07:17 AM |
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if your asking in a very roundabout way if the front needs to be as wide as the back, then no.
Fame is when your old car is plastered all over the internet
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kango
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| posted on 15/1/08 at 10:06 AM |
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No!
I am asking
"Do you have to retain the some off set /ET as the axle needed on the original car"?
What is the optimum off set for 7J rims in front and 8J rims at the rear?
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Mr Whippy
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| posted on 15/1/08 at 10:25 AM |
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Oh right, your worried about the offset. I remember folk use to run into problems with this when sticking very wide rims on their production cars and
then knackering the wheel bearings due to the load not being centered on the bearing anymore.
To be honest on a 7 with their very light weight that shouldn't be a problem but if you can get the wheel centered then all the better. Nothing
technical about it, just measure in between the two bearings and project down, that's the centre of the wheel and get your offset from that. In
reality though I bet the rear body will fowl the wheel unless you use narrow tyres or a wide axle.
I’m surprised no one else has answered on this as they usually go mental on suspension issues.
Fame is when your old car is plastered all over the internet
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britishtrident
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| posted on 15/1/08 at 11:38 AM |
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You won't upset the geometry other than the scrub radius will cause more kick back through the steering and make it even more esential the wheel
balance is spot on.
But would it be a good thing to increase the width even more ? 6.5" is already well on the wide side for the front of a road going Seven.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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paulf
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| posted on 15/1/08 at 11:39 AM |
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As i understand it the important bit is the ET of the front wheels relative to the uprights used to give the correct scrub radius.Cortina uprights
were designed for et 19 and sierra et 38.On the back of the car it is not as mportant apart from allowing clearance for the trailing arms , sierra
wheels will foul the arms.
Paul.
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2b_pablo
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| posted on 15/1/08 at 01:29 PM |
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offset isnt really tied to the width f the wheel. its relative to the centre of the wheel I think so making the wheels wider wont change the
offset.
Id rather go the wother way around and have et19 on the rear and et38 on the front as your way will have the back wheels sitting in a little.
Personally Id get a set of et19 (ish) wheels and fit the set to the car. Running et19 on the rear will do no harm, just means the wheels will sit out
a little (no bad thing) and balance up the car a little.
I run et15 ish all round on my sierra based car. No problems bar the fact that the sierra cycle wing stays need adjusting to come out more to sit over
the wheel.
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