CossiePower
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| posted on 13/3/03 at 11:16 PM |
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Cosworth rear end (Help)
Hello everyone
Newbie needing help advice.
I have a car fitted with a cossie rear beam etc.. I would like to reduce the width of the rear track, but still use the sierra mounting points. Any
advice or a point in the right direction would be great.
Lee
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Noodle
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| posted on 14/3/03 at 09:19 AM |
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Any particular reason why you want to stick with Sierra semi trailing arms?
An easier solution (and geometrically superior) would be to implement a double wishbone IRS. You could keep you Sierra diff/driveshafts/brakes and
junk the semi trailing arms.
Most of the pre-manufactured chassis builders do this. If memory serves me right (not always reliable) Stuart Taylor did a "book chassis to IRS"
conversion.
I appreciate this doesn't answer your question directly but as the old adage goes "If I were going there I wouldn't start from here"
Neil.
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CossiePower
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| posted on 14/3/03 at 04:19 PM |
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My car is built from a steel shell which has the sierra floor grafted in to it. So I was thinking in would need to use the sierra mounting points. I
am not familar with how kit rear ends mount. Does any one know where I can get the Stuart Talyor book you mention as this might help me.
Thanks for your reply Lee
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StuartA
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| posted on 14/3/03 at 04:38 PM |
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The 'book' referred to is 'How to build a sportscar for under £250' (*smirk*). You can find it in most good bookshops or have a hunt for it on
Amazon. It is where most of the builders on here started from. 
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Liam
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| posted on 14/3/03 at 07:09 PM |
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Hello...
Not quite sure what you mean...
a) You want to build a locost using a complete cossie rear end?
b) You have a car with a cossie floorpan (sounds interesting - any more details?) and want to reduce it's rear track width?
If a) i'd recommend ditching the sierra trailing arms and beam and doing your own irs (or getting a kit like the MK indy). There is no Stuart Taylor
book - the book StuartA is referring to does not have plans for double wishbone irs. If you want a book that does get the Tiger Avon book (although
imho the irs design in that aint all that good - MK indy is much better).
If you meant b) then I cant really help. It's gonna be herrendously hard to reduce the rear track without extensively modifying the training
arms/spring positions etc etc. Only other thing I can think of is using wheels with a different offset - but then you are gonna get close to
colliding with teh brakes.
Hope that helps
LIam
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CossiePower
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| posted on 14/3/03 at 10:29 PM |
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Its B..
Its a mk2 escort with a 350 bhp cossie engine and rear end. Most of the body work has been replaced with fibre glass. I know its not quite a locost
but I know how good you kit car boys can be, and I am struggling for a solution.
Ideas I have had:
A) Modifiy the shafts and rear beam springs ect..
B) Build a complete chassis and mount all my stuff in it and put the shell over it.
Is there a kit which takes mk2 escort front suspension?????
C) Copy a kit car rear end and work out a way to mount it to the roll cage and floor.
Cheers Lee
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Liam
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| posted on 15/3/03 at 12:06 AM |
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Excellenté - that sounds awesome!! Got any photos? you could upload them to the photos section here - well you could if it wasn't broken at the
moment. Should be fixed soon though.
Blimey it must have taken a hell of a lot of work to create that beast. I assume it wasn't you or you'd modify your rear track in your sleep.
MK2 escort with sierra track - must look mean. Why do you want to shorten it? Stealth effect?
Anyway - there probably wont be enough room under there to make a double wishbone setup and making a whole new chassis for your body seems a bit
drastic. I reckon your best bet is to fabricate some new trailing arms that use the existing mounting points. The hub carrier (that holds the brakes
too) unbolts off the existing sierra trailing arms so you would just need to bolt that onto some custom made narrower trailing arms, have your
driveshafts cut and shut, and bob's your uncle.
Stephen Gusterson on this list is making a morgan replica and his rear end has custom fabricated trailing arms just like what you would want to build.
They mount with rose joints too. Have a look in the photos section (when it's fixed) or he might pop in here. He might be your man.
Best of luck,
Liam
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CossiePower
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| posted on 15/3/03 at 01:31 PM |
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Your right I did not build the car, but I seem to be rebuilding everything on it.
I have totally rebuilt the engine with wrc head gasket, low comp 4x4 pistons, nut and stud kit, complete crank regrind, uprated big end bolts, new oil
pump, lighten fly wheel, and a big wing baffed sump - had to shorten the deep part of the sump as well to clear cross member.
The front set up had a cut and shut cross member which lowered the rack which gave hugh bump steer.
So I now have, adj lower arms, coil over billy, adj not mounts, compression struts.
The front wheels had 80mm spacers which I have removed now. This makes the front wheels sit just inside the X-pack archs nicely.
So the rear now need to come in 40/50 mm to look right.
Stephen Gusterson what he doing sounds great and the sort of thing that would sort my problem.
Cheers Lee
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Liam
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| posted on 15/3/03 at 02:16 PM |
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That sounds great! Some photos would be awesome.
Speaking of photos go here:
http://www.groups.yahoo.com/group/locost
...and join the group. Go to the photos section and there is a Steve Gusterson directory, in which are some photos of his trailing arms.
Liam
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CossiePower
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| posted on 15/3/03 at 02:45 PM |
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Brillant thats given me some good food for though.
Thanks Lee
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stephen_gusterson
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| posted on 17/3/03 at 11:46 PM |
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okay.
Liam has pointed me here so I will try and give you my two pennys worth!
This is what I have learned, and done for better and for worse. If anything grabs your interest - let me know!
I did put a fair few picckes up before, but I took em all down cos I thought i could make a better job of presenting them than I did.....Id hate to
look like an amateur!
Firstly, and not directly relevent to this post - I found this site the other day .... the guy says he used the sierra rear complete on a locost - I
recon hed be useful to ask questions if you are doing summat standard....
http://www.c.lourie.btinternet.co.uk
I originally wanted to do my rear with a sierra rear, but I just couldnt figure out how to get the really chunky front mounts in. So, I decided to use
all the bits I could to make my own.
The car isnt a 'racer for the road' (although I somethimes wish i'd stuck to the formula!) and if it has average handling, Id be happy. So, i didnt
fancy all the geometry hassles with a full wishbone IRS and I didnt want to use a live axle - but if you are building a std car its gonna save buckets
of time......
I did my rear suspension fairly unconventionally. I thought that the mini and the metro - not renound for poor handling - use rear trailing parallel
(sp?) arms, so I would give those a go. Another advantage is that they are very 'flat' and dont have a live axle bouncing about in the car centre.
This allowed me to have a bit of space for a larger tank, a small boot, and the pronounced triangular shape a morgan has at the back.
However, there is a limitation with rear parallel arms. They are pretty good at holding their geometry on a bump - but not so good (at all) on a body
roll into a corner. Will tend to reduce tyre contact area - but then im not gonna race it and I could run a bit of camber to compensate.
I am told (and chris G can confirm) that a porche 924 has summat like this as a rear wheel drive set up, but not much else has in the last 30 years im
told.
Most cars have semi-trailing arms in this kinda design - which is what the sierra has.....its a kinda compromise to allow a degree of 'roll geomety'
at the expense of the wheel tipping in a bit on a bump.
So, Im would recommend that whatever you do, you follow a more conventional semi trailing if you dont wanna take risks. If you arent narrowing track
too much, then try the same angle that the sierra has.
In my car I cut the brake and hub mounting bits from the rear arms and made up my own. It looks like - if you want to go that far - that the
substantial rear arm bushes could be cut off, the rubbers pressed out, and the tubes welded to your own arms, if you want to go that way.
I went for two rose joints. I used 16mm - Im recon you need something fairly big as they take a fair loading - most should go into the shoker, but
there are still the twisting forces of accelleration.
Be careful to get good quality joints if you go this way and DONT load them by more than 25% of their rating. This is cos they take shock loads, and
most are quoted static.
If interested, I can put up pics of what I did if the yahoo pics dont show enougth.
As far as shortening the shafts is concerened - thats a bit of a pain.
Mine are from a rear disk granada - similar but different (!) from a sierra in that most sieera use a tri type uj on the shafts, and the granny uses
summat called a lobo joint - a metal 'pot' with big balls in it.
I got my father - until recently a metal fabs guy - toolmaker actually - shame hes retired! - to cut one shaft (they are NOT equal length you will
find!) cos the other was right length. I had him turn down one side so it formed a dowel, which was inserted into a recess in the other end. Before
insertion, both ends were angled so that a fillet weld could be run with a gas torch to make a deep penetration weld.
A few comments here.
The shaft is hardened as std. Modding it screws with that. I dont trust my shaft (ooh err). According to Rorty on this site (and Viper?) , its also
best to sleeve the joint by making up a tube to go over it and making deep spot welds at several places. This should then all be trued up in a lathe.
It then needs heating up to a silly temperature - I was thinking of barbequeing it! - and then put into a 250 degree domestic oven, flat out. Turn off
oven so that the barbied shaft cools slowly from 250c. I think this puts some of the hardening back....?
I still have to do the sleeve and oven bit!
If any of that helped, great.
If you need to know more, please ask!
atb
steve
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CossiePower
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| posted on 19/3/03 at 10:15 PM |
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Many Thanks for sharing your knowledge it has been great.
I am planing on laying under the car and having a few fags at the weekend.
Lee
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