locoboy
|
| posted on 30/9/03 at 09:16 AM |
|
|
off centre diff
Dear all,
I am wanting to pick a few maths brains here!
I have a car with a live axle and the diff is not in the centre of the axle it is nearer the drivers side.
My car is a norrow bodied version and as a concequence the transmission tunnel follows the line of the prop shaft from central at the gearbox end to a
few inches off centre on the drivers side at the diff.
I want to change the back end to IRS.
i do not however want to re allign the transmission tunnel so it is straight down the centre of the car.
I need to know if it is possible to achieve the same suspension characteristics with a long set of wishbones on the near side and a shorter set on
the off side so i can mount my independent diff at the end of the tunnel (offset to one side). I would have to get a shorter driveshaft for this side
too i assume.
Hope my predicament is clear to you all and any info will be a help, thanks.
ATB
Locoboy
|
|
|
|
|
Spyderman
|
| posted on 30/9/03 at 10:40 AM |
|
|
In short, NO!
The wishbones need to be the same length either side regardless of where the diff is.
You could however make both sets of wishbones the same shorter length and have different length drive shafts. Most transverse layouts are like
this.
How far off centre was/is your live diff?
Most live axles are slightly offcentre to accomodate the crown wheel and pinion, leaving the drive shafts the same length.
This puts the left side of tunnel running parralel to centre line and right side of tunnel kinked at rear to offside.
Terry
ps, no doubt someone will correct me if I have this wrong.
Spyderman
|
|
|
locoboy
|
| posted on 30/9/03 at 11:25 AM |
|
|
Spiderman,
offset is only 2-3 inches but the tunnel is tight at the back, it would definately contact the tunnel rails if i ran the shaft straight down the
middle of the centre line of the car.
Thanks for the info, hadnt thought about the same length bones and odd lengths of drive shafts, will any decent engineering shop be able to shorten
the shafts? Do the sierra ones have splines on both ends? if so can an engineering shop re-spline it?
Is it possible to run the shafts at an angle fore and aft? Ie, viewed from above they would not exit the diff at 90 deg to the centre line? more of a
question of interest than something i would consider doing.
Thanks and any more info greatly appreciated, i though this project was out of my reach until you explained how it could be done.
[Edited on 30/9/03 by colmaccoll]
ATB
Locoboy
|
|
|
ned
|
| posted on 30/9/03 at 12:15 PM |
|
|
the sierra driveshafts are different lengths, because the dif is wider on one side (but is still mounted centrally) if this is of any use...
Ned.
beware, I've got yellow skin
|
|
|
GO
|
| posted on 30/9/03 at 12:41 PM |
|
|
And you can run the shafts at an angle fore and aft, if you like - I believe they may angle slightly backwards on the sierra?? May be wrong,
didn't remove mine myself.
[Edited on 30/9/2003 by GO]
|
|
|
locoboy
|
| posted on 30/9/03 at 12:43 PM |
|
|
Ned,
I have been made aware of this before but as my car is not a wide version it has as far as i know a mkI rear axle and the standard sierra shafts would
make the rear trach too wide (right?)
ATB
Locoboy
|
|
|
JoelP
|
| posted on 30/9/03 at 12:48 PM |
|
|
my personal opinion is if i had a choice between moving a chassis bar or chopping and balancing a drive shaft, id just modify the chassis and use a
central diff. Just my opinion.
|
|
|
locoboy
|
| posted on 30/9/03 at 12:58 PM |
|
|
was half way through writing a reply Joel about all the hassle of chopping the old one out and removing all the ally pannels inside and all the other
shite that goes with it and realised its probably not that much work.
I need to get a propper look at the car and measure how far off centre it really is and if the one side is parallell to the centre line and the other
is offsett etc, before i look at re making the backbone of my car!
ATB
Locoboy
|
|
|
ned
|
| posted on 30/9/03 at 01:21 PM |
|
|
col,
i know luego can do exchange shortened driveshafts as they used to shorten them for the book width velocity before the xt (wider track) version was
released...
this is probably what i'll do with my own irs design as I already have book front wishbones.
Ned.
beware, I've got yellow skin
|
|
|
jcduroc
|
| posted on 30/9/03 at 03:59 PM |
|
|
quote:
Originally posted by ned
the sierra driveshafts are different lengths, because the dif is wider on one side (but is still mounted centrally) if this is of any use...
Ned.
Ned
I think the diff is mounted 1cm offside to the left.
JCM
|
|
|
JoelP
|
| posted on 30/9/03 at 04:59 PM |
|
|
On mine the top mounting plate appeared exactly central, with the diff slung off it a little to one side. I sure hope it was exactly central cos thats
where its going!
|
|
|
Liam
|
| posted on 2/10/03 at 02:16 AM |
|
|
Sierra diff is mounted so that propshaft flange is dead centre.
Col - from what you're saying, even if you rebuild the tunnel and mount your diff central, you'll want to shorten both shafts anyway to
get a narrower track! Save yourself the bother and mount your diff offset. Sierra track is about 6" wider than escort (about 3" per
side) - and you say your diff needs to be offset about 2-3". So offset your diff over towards the drivers side 2-3" - that moves the
passenger side wheel to about the correct position with the standard shaft, then get the other shaft shortened 4-6" to put the driver side wheel
in the right place. No tunnel modding and only one shaft to cut and shut.
Liam
Make the wishbones symetrical!
|
|
|
locoboy
|
| posted on 3/10/03 at 08:20 AM |
|
|
Liam. You are a god!
ATB
Locoboy
|
|
|
