Track suspension advice

[milescook]

Right, the time is approaching when I will need to put my track car, which will do limited mileage to circuits, on something that resembles race suspension - sorry could you look at my link in my signature below for further info, or my build thread for a quick synopsis where it is so far.

My key criteria are:
Cost up to £600 new or (more likely) used.
I'd like to stay in board springs on the rear, as I'd like to try out some top tips which generally say, "don't stiffen up the rear too much", as PBMW runners find traction an issue.
I have a rear welded strut brace - that's definately not part of the roll cage - coilovers on the rear I've heard tend to fall out with this concept and break things?

I'm reciting possiblly part guff/part twoddle/part gems, I appreciate everybody has an opinion and not always to they agree, so the more tips the better!

Many thanks for your help

[Black_Potato]

Coil overs to inbound is mainly a question of packaging and I have not seen any real argument between them other than this.

here is a brain dump...
coil over has loads of spring choices in both length, rate. The are normally height adjustable as part of design through a spring collar.

inbound can be adjustable but you would need addtional spring platters, also using compound springs isnt as easy, i.e. something like 50lb+250lb in 2 springs with a connecter is possible in coil over.

Inbound spings are normally easier to change as you dont need to dismantle the damper to get them out.

inbound could give you more space for a larger diameter damper, hence less cooling issues etc..

That said the real crux f it is as you say getting the spring rate, and subsequently the damping correct. the key point here is that there is no reason why you cant get the spring rate correct on coil overs, its just you need to know the ratio for each options.

I dont have these to hand but its something like 44% for coilover when compared to inbound. so inbound of 500lb would equal 220lb coil over. I'm not sure what the current thinking is in PBMW with regards Marangoni but from the breif test I did on the tyres I would say that something like 225lb for coil over would be a good place to start with a view to going up or down in 25lb based on preference and overall roll stiffness of the car.

To a lesser degree you should also take bush material and your upper mounts into count as they have an effect as well.

[Demlotcrew]

Hmmmm, controversial topic, my setup is a bleek contrast from what is the norm in the UK E30 race scene, very large rear anti roll bar (larger than what most run on the front), high spring rates as a true rear coilover (over 380lb dual rate progressive spring) and I have no issues with oversteer (In fact I am waiting for even stiffer springs to come from AST this friday).

I have done a few UK circuits (in the dry) and I really don't understand where this lack of rear end grip everyone complains about is, because I certainly dont feel it in my car.

Damper technology plays an ever increasing role, dont expect great handling from a kit costing £600, you might be lucky like Kos to find a used Intrax kit for less than that, but it will most certainly need to be rebuilt.

Just to add to the brain dump above, with a true rear coilover, the longer spring ads ease of tuning and offers much better characteristics over a stubby inboard half pigtail spring.

Andrew

[Black_Potato]

One point with the PBMW guys is that they run an open diff, hence compliance is very important to drive out of a corner.

That said most people I know running M3 derived setups also run light or no rear ARB.

As you say it takes lots of views and not all drivers like the same, either way getting it all balanced is key.

[Demlotcrew]

Oh, I didn't know the regs prohibited Lockers, thats something different entirely! What I'm running relies heavily on a nice high locking clutch pack, I have never driven this setup with an open.

[Stonkin]

I've been very keen to see replies to this as i to have been reading a lot about what suspension setup to go with for my track car build. I think i would far rather use coilovers all round rather than the oem style setup. I find the topic quite confusing and want to make sure i dont waste money buying items and have to replace later down the line. I've searched through lots of threads on here, and quite a few seem to use the Gaz Gold kits. Some people are telling me these are 'cheap' kits and that i should look at BC,HSD's, H&R etc

I would really appreciate any comments on these to steer me in the right direction. I am not looking to spend stupid money, but i would like to buy once and know i've made the right choice. The Gaz Golds i was looking at seem to be around £900, which will then need the uprated rear rose jointed top mounts i believe?

I will also fit front and rear strut braces and either H&R or eibach arb's. I know the H&R are thicker but is there much difference in these 2?

Do people also recommend the full powerflex bush kit?

Sorry for all the questions Am just not finding all my answers with searching so far and would love to hear some opinions from those with experience

[rix313]

The price I paid for my AST's wasn't far off what you'd pay for a set of GAZ golds + top mounts and the AST are far superior. Not sure what sort of deal Andrew managed to get of his but its worth asking, just be prepared to wait!

I'd personally save the £50-£60 on a rear strut brace and go down the pub with the money instead tbh, and I dot even drink that much...

H&R stuff is generally known for being a bit more 'hard core' and stiffer but that shouldn't take anything away from how great the Eibach kits are.

As for bushes I know some of the PBMW boys run the standard rubber bushes in the rear subframe to chassis mounts to help them with traction, but this could be linked to them running open diffs again.

Shopping around is key really, when I was looking at ARB's, the UK AST guy had them on promo and was able to do a good price on them. Sadly I didn't have the spare spondies at the time.

[DanThe]

I took the rear H&R ARB off mine pronto while the car still had an open diff fitted, with the torsen diff I never felt the need to put it back on, now have a 75% locking clutch plate setup but yet to drive on track with it

[Stonkin]

Thanks guys. The AST's certainly look good, but more into £1300 and upwards depending on the model from having a quick search. This is probably a bit more than i wanted to spend for coilovers.

Interesting that you wouldnt recommend the rear strut brace.

Will welcome any other feed back on kits

[Demlotcrew]

Why not remove all your Anti roll bars?

[Demlotcrew]

The price I paid for my AST's wasn't far off what you'd pay for a set of GAZ golds + top mounts and the AST are far superior. Not sure what sort of deal Andrew managed to get of his but its worth asking, just be prepared to wait!

Looking at the photos, my kit seems very different to what you have, and I only wish it was marginally more than Gaz Golds

[Motorhole]

I've gone for the budget option of fitting a standard 325i sport rear anti-roll bar (14 mm I think?) with the intention of trying to keep the rear compliant. Front is a 24 mm 325i Cabriolet anti-roll bar with drop-links that pick up on the struts rather than the wishbones. All in, with new drop links, polybushes, cups etc you're looking at about £70, compared to £200-odd for the H&R and Eibach kits...but again, as yet to drive it. Guess it all depends how much you want to spend.

[DanThe]

Cabby front ARB is 21mm, H&R ARB kit is now over £300!

[Duke137]

Cabby front ARB is 21mm, H&R ARB kit is now over £300!

There was an H&R kit on ebay ended yesterday that didn't sell, might be worth a cheeky PM...

http://www.ebay.co.uk/itm/271081228113? ... 1423.l2649

[Motorhole]

Cabby front ARB is 21mm, H&R ARB kit is now over £300!

Thanks! Too many numbers.

[milescook]

Hmm, I guess Gaz is still a decent option then. I'll probably go with that. I'll be adding a bit to my budget for top mounts and other goodies, if someone is selling a complete used set that hasn't been battered, please point them in my direction!

[redcar]

Who on earth would remove their rear arb for track, that's a ridiculous idea lol.
I know cara that lap 7:30 round the ring with 28mm rear arbs!

[maxfield]

Who on earth would remove their rear arb for track, that's a ridiculous idea lol.
I know cara that lap 7:30 round the ring with 28mm rear arbs!

For grip. It seems to work as a lot of people do it.

The ring I imagine is completely different being as a lot of it is high speed cornering.

[Demlotcrew]

Clearly high speed cornering doesn't require grip?

Correctly setup cars will be running rear arbs, even in the wet.

[Black_Potato]

The only thing I can take from this thread is that nobody here actually understands the principles of setting up a race car, or if they do they are unable to communicate them well.

A competitive racer of several years I still include myself amongst the un educated masses and rely on either hit and miss or a professional such as Steve to do the work directly or in directly for me.
http://www.guglielmimotorsport.co.uk/st ... ielmi.html

My car setup is largely based on John Wilcocks race wining M3 which was setup by steve and runs relatively soft spings and with a low rate rear ARB or with it disconnected.

Its also worth mentioning that this is based on my dampers, aero package, control tyres (R888) in the race series and so on. If I was building a car that ran on another tyre, say slicks then the requirement may well be different in many component.

Anyway in conclusion, lots of netspurts and very few experts here. If you want pub conversations this is a place for it, however if you want your car setup and you dont know how to do it pay somebody who does. If you cant afford that make friends with somebody who has a similar car in as many dimensions to yours as possible and buy them beer until they disclose their secrets.

[Demlotcrew]

Project 8 is hardly the race series to benchmark against Especially when your man is the only one in class C, sorta hard not to come first

This no ARB setup is purely a UK phenomenon, Gr.A M3's were running anything from 14-22mm rear ARB's and spring rates ranging from 90nm-150nm (again on the rear & true coil over).

Its your choice to model your setup from amateur racers, the rest of us who have done our research reserve the right to model ours on far more developed cars, please do let us know when your next track day is, it would be really good to compare the differences.

[DanThe]

The only thing I can take from this thread is that nobody here actually understands the principles of setting up a race car, or if they do they are unable to communicate them well.

Demlot has issues with communication in general

Ive just bolted some Gaz golds to my chariot, I might hang up the front arb too and rust the bonnet

[redcar]

Haha, this thread is very frustrating.

So what would your opinion be, of a car weighing 1100kg, running r888s with a 32mm front arb and a 28mm rear arb?

What's all this talk about having £300 arbs, but leaving them disconnected. That doesn't make sense to me.

Black potato, when is your next track day, I would love to see your "competitive racer." Especially the "aero package!"

[Black_Potato]

I'll be testing in the next few weeks, if you want to come along and have a ride you are more than welcome. The point with competitive racing is its a far more objective test than track days as you can bench mark your setup against other cars and as a result develop a setup, sticking something on a car and doing a few trackdays tells you very little.

Re Aero package of my car is very limited (i.e. there isnt one ), however the point is if you were allowed to run splitters and and significant rear wings we we arnt it would have an effect. This in turn would mean the the requirements of the suspension system maintining the car in a given angle of attack changes, hence arbs and lots of other things would change.

Re Andrews comment... Forget P8R my point wasnt me or the race I compete in, have a look at Steve's background and decide if you know more about car setup than him.

My underlying point still is that few here seem to actually get it in the detail, and I'm not saying I do either. However if people here are actually car setup experts please share some of your successes and maybe some of your detailed suspension dynamics. Then detail all your carsetup including dampers, valving, springs, tyres, aero, bushes, weigh etc.. and people can see if thats of any use to them.

Or alternatively feel free to say that a car with a 2000lb springs with a 50mm ARB once went around Laguna Seca in 1.23 hence thats why I you think you are right.

[redcar]

I'll be testing in the next few weeks, if you want to come along and have a ride you are more than welcome. The point with competitive racing is its a far more objective test than track days as you can bench mark your setup against other cars and as a result develop a setup, sticking something on a car and doing a few trackdays tells you very little.

Re Aero package of my car is very limited (i.e. there isnt one ), however the point is if you were allowed to run splitters and and significant rear wings we we arnt it would have an effect. This in turn would mean the the requirements of the suspension system maintining the car in a given angle of attack changes, hence arbs and lots of other things would change.

Re Andrews comment... Forget P8R my point wasnt me or the race I compete in, have a look at Steve's background and decide if you know more about car setup than him.

My underlying point still is that few here seem to actually get it in the detail, and I'm not saying I do either. However if people here are actually car setup experts please share some of your successes and maybe some of your detailed suspension dynamics. Then detail all your carsetup including dampers, valving, springs, tyres, aero, bushes, weigh etc.. and people can see if thats of any use to them.

Or alternatively feel free to say that a car with a 2000lb springs with a 50mm ARB once went around Laguna Seca in 1.23 hence thats why I you think you are right.

Clearly you haven't seen any of the recent DN6 videos.

Do you have any details of your car? suspension, springs, tyres and bushes etc.? When's your next track day. Would love to come and have a look

[Demlotcrew]

Im off in the second week of November, I will try and make time to call Steve and ask why he advises what you advocate.

Just to add Johns race winning M3 is equipped with aero, if your car is based on his and you have no aero, that makes no sense to me?

[Black_Potato]

Sure, let us know what he thinks. When i have spoken with him he as always advocated compliance. Talking with john and dave recently the plan is to get steve down for another setup day, not sure if steve has been informed of this yet though !

Re aero, johns regs are not that different from mine, he is class C im class D (sub 2ltr) he can run an evo rear spolier. With regards the comparison between the 2 cars, the bush, damper, tyre, spring setup is similar. The 320is isnt a pbmw car.

[redcar]

Sure, let us know what he thinks. When i have spoken with him he as always advocated compliance. Talking with john and dave recently the plan is to get steve down for another setup day, not sure if steve has been informed of this yet though !

Re aero, johns regs are not that different from mine, he is class C im class D (sub 2ltr) he can run an evo rear spolier. With regards the comparison between the 2 cars, the bush, damper, tyre, spring setup is similar. The 320is isnt a pbmw car.

May i ask, what exactly is the spec of your car, suspension, arbs, bushes etc.

[Black_Potato]

No problem giving high level stuff out on a I'll show you mine you show me yours basis. I have some of it to hand, some small detail I may have to hand I may not want to completely disclose. ;)

1989 320is, rebuilt from a lot of spares (no V5 etc) to compete in <2ltr semi historic series such as TTRS (Pre 93) or Khumo etc. Initial intention is to get the platform reliable and me used to the LHD, DL Box etc. I’m a car enthusiast who can drive a bit, not a racing driver as such.
Refreshed engine, ready for hotter cams (pocket pistons, race manifold etc) , ECU etc but at the moment being tested with some mild Shrick cams on a chiped OEM ECU, circa 210hp.

Control tyre is R888, current 195 profile but toying with 205. Suspension is Custom built units by GAZ, independent bump/rebound & remotes, Ground control top mounts, M3 style ARB pickup with custom drop links, OEM eccentric bushes, Eibach adjustable ARB. Rear arb is the stock BMW item at the moment, Eibach ARB may get tested but most folks (I know”¦) to warrant anything much stiffer than that. Rear is rose jointed top mounts eccentric trailing arm bushes to allow adjustment, subframe bushes (don’t recall, probably OEM or a light poly). Spring rates I don’t have to hand but I’m not sure if I would offer them openly, however they are relatively soft and comprise Eibach main springs and helpers. Think 500lb front 250lb rear for the coil over main springs and you are not a million miles off.

Diff is around 75% locked, Ratio is pretty close, would need to confirm exact ratio. Work on brakes ongoing, along with a quicker rack I expect. Engine is mounted on vibra technics mounts.

Something not mentioned by many as well which may contribute to over all stiffness. We run fully welded cages to the turrets, Diff pickup, re enforcement in the floor, gusset strips etc. Road cars are a lot more bendy.


So.. whats your background/spec ?

[redcar]

Your cage sounds good. So does the diff! How many clutch plates do you have in your diff, and what are the ramp angles?

Why are you running OEM or light poly subframe bushes, as opposed to something absolutely solid?

My rear subframe is raised 12mm. Solid ertalon (plastic) subframe and diff bushes. Trailing arm bushes are a hard poly.

I noticed an absolutely massive difference when putting solid bushes on the back as well as raising the rear subframe. The car is much tighter and you can really feel when it starts to loose grip. It's not twitchy/snappy at all anymore. BTW. the OEM bushes i took out were very recent replacements.

[Kos]

Damper technology plays an ever increasing role, dont expect great handling from a kit costing £600, you might be lucky like Kos to find a used Intrax kit for less than that, but it will most certainly need to be rebuilt.

Penske actually ;)

Even if I spend £1000 re building/overhauling them it will still put perform anything that's availlbale of the shelf for £1600

[Black_Potato]

Your cage sounds good. So does the diff! How many clutch plates do you have in your diff, and what are the ramp angles?

Why are you running OEM or light poly subframe bushes, as opposed to something absolutely solid?

My rear subframe is raised 12mm. Solid ertalon (plastic) subframe and diff bushes. Trailing arm bushes are a hard poly.

I noticed an absolutely massive difference when putting solid bushes on the back as well as raising the rear subframe. The car is much tighter and you can really feel when it starts to loose grip. It's not twitchy/snappy at all anymore. BTW. the OEM bushes i took out were very recent replacements.

I'll ask Dave (Mechanic who runs our race cars) what the diff setup was in detail next time I speak with him. Likewise the rear sub frame bushes. I stripped the rear beam, arms etc.. and re assembled them myself but he fitted it with the subframe bushes so I didnt see exactly what went in.

[Demlotcrew]

Sounds to me that we could show Dave the builder a few tricks

[redcar]

Black_Potato, i find it highly amusing that you're quick to point out that people on here don't have a clue about suspension setup etc. Yet you appear to have little idea about what parts are actually fitted to your car! Would the parts i've asked you about (subframe bushes for example) not form a vital part towards how you are expressing your opinions regarding suspension setup?

[Black_Potato]

Andrew, maybe, he worked with steve for a lot of years and builds race cars for a living. he isnt the most reliable guy on the planet but he gets things done and has a lot of experience.

would be interested in hearing more of your car/business, its good to go off pieste some times.