Technical uprate 70SX susp to Turbo spec

[fostertom]

Following on from https://www.fiatforum.com/uno/279997-eper-uno-turbo-mk1.html?p=2846718 , I want to uprate the 89 62k rust free 70SX's susp and brakes, pref to UT standard as that's a formula that works.

So apart from springs and shocks which will be new, anyone tell me what other susp differences between mk1 70SX and mk1 UT? e.g. is the ream twist beam same or stiffer?

 

[Louie Bee]

Not sure if the 70sx had the front anti rols bar?

The Turbo may sit higher then the SX

It's easier to fit rear calipers if you have the whole rear beam off a turbo, but not impossible without, but loads of fiddley bits.

Rear hubs are diferent
Handbrake cables are diferent (bit that mates to calipers don't have the eye.

IMO your better off with a whole Uno Turbo and moving bits across bit by bit as the most cost efectiv way

 

[benjamin7]

apart from the brakes, springs and shocks they should be the same
My old 1.4sx had the front anti roll bar, as far as I know there is only one size.

A real rust free uno, perfect for a turbo swap.

Grtz, benjamin

 

[fostertom]

[FONT=Verdana, Arial, Helvetica][FONT=Verdana, Arial, Helvetica]I am told 70SX susp is uprated re ordinary Unos, what makes the difference?
Is UT a further susp uprate on 70SX? - what makes that difference? Front roll bar added? Stiffer rear beam?
As UT is quite a lot heavier than 70SX, simple susp uprate of 70SX to UT susp might not be gd idea.

In fact, leaving out UT, what the best susp uprate I cd do to 70SX, for the road?[/FONT][/FONT]

 

[fostertom]

Well I've learned a lot, thanks to e.g Lewey here, and e.g http://www.sfconline.org.uk/forum/topic.asp?TOPIC_ID=4816

So no great differences, mk1 70SX vs UT.
Springs shocks wheels obviously, and the 70SX has no ARB.
Apart from them, all bushes, wishbones, front uprights, rear beam are same, as far as geometry, stiffness etc.
Only differences are quicker rack, stronger 3-bolt top front strut mount (metal) and different top front strut rubber.
I need to know if the last is important, and if so will it fit the ordinary 2-bolt top front strut mount (metal).

Another difference is 70SX is only 770kg vs UT 895kg, nearly all at the front.
That's a big difference, handling wise.
How will that affect ARB stiffness? (fitting a mk2 one).
How will that affect springs and shocks, meaning a 40mm lowered kit, which I guess will be optimised for UT's front-biased weight distribution.
As 70SX is much lighter than UT at the front, will the ARB and front springs in the kit be too strong?

 

[lewey]

At the end of the day, suspension setup and spring rates for the road is all about compromise. The standard FIAT setup for the UT was a compromise that most could live with. Using that setup on your 70SX will obviously improve roll behaviour, which will be handy if you want to drive fast in high speed corners. It might introduce unnecessary understeer though which will be the predominant behaviour anyway, despite your lower weight.

I don't know what is meant by the 2 or 3 bolt top strut mount. I've only ever seen 3 bolts in the top of front turrets on all models. What are you referring to here and what do you see when you look at your car? ePer has same parts numbers in this dept. for all models on the mk2 for example.

 

[fostertom]

I don't know what is meant by the 2 or 3 bolt top strut mount. I've only ever seen 3 bolts in the top of front turrets on all models. What are you referring to here and what do you see when you look at your car? ePer has same parts numbers in this dept. for all models on the mk2 for example.

Sorry, that should read 3 bolt (what I see on ordinary Uno incl diesel) and (more) bolts (what I see in eper pic for UT - the plate you see on top of the wing/turret). In eper there's an amazing no of alternative part nos for ordinary Unos incl diesel, plus different no for the UT one, which looks bigger with more bolt holes.

It might introduce unnecessary understeer though which will be the predominant behaviour anyway, despite your lower weight.

Are you saying UT-type susp setup may understeer more than ordinary Uno without ARB,
or that with UT ARB added but lighter front weight than UT, that will understeer more than UT?

 

[lewey]

Regarding the turret plate, these are plates to support various things like header tanks which are different in design for many models. I have never heard of them being a factor in suspension performance. Curious.

The lowest weight Unos will understeer more with an ARB fitted. These ARBs are fitted as a comfort device for the road, not a handling aid per se in my opinion. They allow you to corner faster, more comfortably due to reduced roll than the soft dampers, fitted for comfort, would ordinarily let you. If you are cornering at speeds that would significantly affect the suspension geometry and therefore tyre contact patch, an ARB would help potentially.

I think the problem with any of these discussions is the idea of "best handling". For the road you need a compromise that will cope with poor road surfaces and one that you can live with long term. You don't have that much power presumably, so how far do you really want to go? Most people would agree that all the standard Uno setups were higher and softer than most enthusiastic drivers would like. Perhaps a standard UT setup would be a sensible upgrade for you, but I can't know whether you would agree.

I'm thinking about putting 900lb springs in my Uno track car because it still rolls too much at 100MPH around Donnington's Craner Curves, yet on the road I curse it's back-breaking ride.

 

[fostertom]

Thanks, it gets clearer. I cd always disconnect the ARB and see which setup I prefer. Don't actually mind body roll, at road speeds and with 65bhp, as you say.

The off the peg spring/damper kits, 40mm lower I'm thinking, are I expect optimised for UT, with ARB and heavier front end. I still wonder how well they wd work on 70SX with lighter front end and maybe no ARB.

Surprised Fiat didn't put in a stiffer rear beam (stiffer in roll) to balance the front ARB. surprised no one does an add-on ARB for the rear.

 

[fostertom]

In the Cann Durant article https://www.fiatforum.com/uno/283131-cann-durrant-magazine-articles.html , [FONT=Verdana, Arial, Helvetica][FONT=Verdana, Arial, Helvetica]Julian Durrant's non-turbo car interests me most. The article finds it the most fun of the 3 cars, due to its revvy character and better handling esp lighter, better feel steering. Any guesses how this was achieved (so I can copy)? Less front end weight prob - what about ordinary vs UT quick rack? Obviously has ARB. I still wonder whether springs (as sold in a typical lowered spring/shock kit) shd be different, UT vs uprated non-turbo, as front/rear weight distrib is so different.[/FONT][/FONT]

 

[gtirx2]

The uno turbo quick rack is 3.4 turns compaired to the 4 turns lock to lock on a normal uno,worth changing if you can find one imo.

Not that my test was fair as i had shorter overly stiff spax shocks at the back and stock shocks at the front, but when i lowered my 45 with spax 40mm springs the front sat way to high and i ended up having to use some -60mm's i had laying about on the front to get it to sit right.

Also if you try -60mm's on the back it sits about 1cm off the bump stops.

This was possibly due to the weight difference in the engines?
Also 60mm springs in the front dislocate from standard shocks by a vast amount when jacked up and is an mot fail.

I am hopeing just to use normal 70sx shocks on my 45 once its been converted to turbo,as i want a sensible ride and the 70sx shock were cheap.
You get an uno to stiff and it turns in to a horrible car to drive on ****ty british roads, crashing about everywhere.

God knows how i will get on with the 70sx shocks but thats the plan,but i am not looking for an all out handeling car nowadays really.

With the above 60/40 setup with the stuck on pretty stiff spax rear shocks and stock fronts the car handled terribly.
It would lift off oversteer real bad and was just all round crap tbh,on hill brows it would jump you out of the seat due to the too stiffer rear end.

On my old uno turbo though i had a full set of adjustable avos and strut braces and that thing used to handle brillently,no lift off understeer at all and very very predictable with understeer all the way, but it would always tuck in nice if you eased of the power.
It was still a bumpy horrible ride though tbh.

Tyres have a lot to do with it all though, as my ones at the moment are gt ditch finders lol,a good alignment setup can also make a world of difference.

Strut braces are also a good idea imo,but its hard to find a rear one that bolts to the turrets and not the shock tops for an uno,you end up having to make yourself one like i have had to.

Here is how the 45 sits with the -60/40mm drop,its still a bit low at the rear compaired to the front.

 

[fostertom]

That's v interesting. Does the following sound right?

A '40mm lowering' spring set lowers a non-turbo's rear by about 40 as intended, but leaves its front too high. This must be because the non-turbo is a lot lighter at the front than a UT. Aftermarket springs, I guess, assume it's for a UT, so what would lower a UT's front by 40mm as intended, is too strong for a non-turbo's lighter front end, so leaves it riding high.

The overall weight difference is 770kg vs 895kg, and I am told nearly all of that difference is on the front.

I don't know what front:rear distribution is, but say it's 65% front, 35% rear on a UT.
That wd give 582kg front, 313kg rear.

Non-turbo is 125kg lighter - say 100kg of that is off the front, 25kg off the rear. Gives 482kg front, 288kg rear.

With 40mm lowering springs intended for UT, used on a non-turbo, rear will be lowered 37mm, front will be lowered only 33mm - I think?

The front ARB will likewise be effectively stiffer in roll. Both the too-strong front springs and the effectively stiffer front ARB will give considerably increased understeer, AFAIK.

You had to use shorter UT-intended springs to get the front lower, but what we need is not shorter, but weaker (lower rate) front springs.

What you reckon?

 

[gtirx2]

Sounds about right.

Like you mention i am hopeing its the weight difference causing the front trouble, with the spring being a to higher poundage for the 45's weight,should sort its self out once i get the turbo motor in.

When i used the 40mm's in the front it really did not make much difference from the stock setup if i am honest,it was still sitting way high.

As long as the front spring seat is in the same place on the actual shock and not different between the turbos and other models i should be alright,as i am not sure if they were turbo specific shocks that i used on the front.

I can remember swapping from avo to gmax shocks on the front of my old uno turbo years back and that actully lifted the front ever so slightly,proberly just because the old avos were worn out.

But i am pretty sure all the shocks spring seat heights are basicly the same across all the models?

The spax springs you can buy for the uno are listed for all the models from 45,75 to the turbo so i dont think its the shocks causing the issue.
But then saying that if they are listed for all the unos maybe its me doing something wrong somewhere.

Not that i have looked into it with other people with non turbos and lowering, but for me it was an issue using the same height springs and getting it to sit right.

I will have to compair them to the gmaxs i have on another uno,but i am 99% sure there the same height spring seats.

As for the weight distribution most is proberly at the front with the turbo setup,bigger rad,oil/intercooler and holding more fluids and mutiple other things stuffed in there lol.
Not really much extra on the inside except electric windows and a few extra plastics,and at the rear the only difference is different hubs, discs and calipers and proberly a larger tank.

Not to sure what i would surgest tbh,as i am just hoping my problem will sort its self out when i swap the engine,where as you need to be sure before you start spending money on springs etc.

 

[fostertom]

Fact that they sell one kit for UTs and all the 'ordinaries' says a lot - i.e. they haven't thought about the difference that front weight difference makes. If front:back ratio stayed same, UT vs ordinary, wouldn't be so bad, the effects wd remain balanced, front to rear.

Seat ht on the strut - that's a thought - needs checking (must be a full factory data book(s) somewhere). If that's another thing the kit suppliers haven't thought about, then maybe paying for coilovers is the way to adjust that out.

 

[lewey]

Generally speaking, the after-market stuff isn't well thought out as you say. It isn't possible to have one set of springs suitable for a range of cars and engines, they just pick one that is considerably uprated so you'll notice. I would guess that any testing, if any was done at all, would have been done with a turbo car. Choosing the right suspension brand for any old car is basically guesswork and pot luck IMO. Objectively, the designs are poorly conceived and subjectively you can't rely on other people's opinions of ride quality. I've bought some Koni adjustables for my road project Uno in an effort to luck into a useful setup.

 

[fostertom]

Thanks - beginning to get that picture.

Got any idea on this question if UT spring seats on the strut are in fact at different height above the hub, than other Unos?

Konis are the grand daddy of adjustable shocks and say 10-15yrs ago they just had 3 notches on the adjuster, and had 'old fashioned' non-gas dampers while others were going to gas. Konis still seem to be considered superior - why is that? Are they still non-gas and a bit old fashioned?

In general, got any advice on how I shd proceed, which spring supplier best to consult, to end up with a nice-handling slightly lowered non-turbo road car? Is there no way other than buying and trying different springs, as if I had a race workshop at my disposal?

 

[lewey]

If I were to guess about spring seat heights, I would say they were the same, but if someone has told you they are different, then perhaps they are. Konis these days are gas and are adjustable through 20 positions or something, but are useful though a smaller range of about 5 "clicks" normally. Konis are considered superior because they are expensive, good quality, German and some review well.

I don't know enough about suspension and car dynamics to calculate a spring rate you should aim for and the suppliers don't tell you anyway. You have to go on review of others and trial and error. See what you can find on the second hand market that haven't been used long or at all. Probably the more you spend, the better the experience. Probably the lower you go, the worse everything will be.

 

[gtirx2]

I would not worry about the spring seat height to much as i am pretty sure there all the same,it was just another possibilty as to why it was sitting high at the front.
Its more than likely the springs that are the issue here.

 

[fostertom]

Thanks to all

 

[fostertom]

[FONT=Verdana, Arial, Helvetica][FONT=Verdana, Arial, Helvetica]Need to change that calc. Wd greatly appreciate data on a) 70SX and b) UT standard springs, front and rear, free length and rate; also front and rear axle weights for 70SX and UT. Have acquired factory data/manuals for 124, 128 but no factory stuff of any sort, yet, for mk1 Uno.[/FONT][/FONT]