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BC BR Series Coilovers
#1545283
23/07/2015 11:07
23/07/2015 11:07
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Joined: Feb 2006
Posts: 5,391 Essex
Trappy
OP
Forum is my life
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Essex
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I’ve just had the BC BR series Coilovers fitted to my car and it clearly needs to be set-up properly. I’m after what might be called a ‘fast road’ set-up and would like to get a better understanding of damper rates before taking it along and given it to someone else to sort out for me.
I have the 6kg/mm front and rear springs and have been trying to read up on what sport of damping level should be required to get the best level of comfort vs grip. I’d really rather not just keep experimenting with different settings, it’s too time consuming, costly and, frankly, it’s only maths and so should be pretty straightforward to calculate to a good starting point at the least.
As the ride height is mostly independent to the spring / damper rates, and the spring rate is fixed, I’d like to focus on the damper rates.
These coilovers have 30 clicks on both the front and rear (though it feels like 34 on the front adjuster?) – for starters, I don’t know what level of damping these correspond with, which I’m guessing is pretty fundamental!
The rears are tricky to get too and so not something I’ll be doing more than once if I can help it – do it once, do it right.
Now, given that each front corner is basically twice the weight of the rear corners, it would seem to me that the damping force would have to be a LOT more. I haven’t seen anyone going for this ratio on the ‘New make of coilovers’ thread – why is that?
At the moment, the rear dampers are set to 5 clicks from hard (so 25/30) and the fronts are set to 12 from hard (so 18/30). The tracking is so far out that it’s pretty impossible to work out how these coilovers perform because I just get rampant power on and lift off understeer (WTF is that about!?) at the moment. The new AD08Rs aren’t properly scrubbed in yet either.
One other question about these – do they permit corner weighting because this is something I know these cars really suffer from being a left hand drive design.
Any help on this would be greatly appreciated as I’m looking to get the work carried out within the next two weeks.
F****** b****** thing...
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Re: BC BR Series Coilovers
[Re: Trappy]
#1545287
23/07/2015 12:19
23/07/2015 12:19
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Joined: Dec 2005
Posts: 17,370 Staffordshire
Nigel
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I thought the rear damping adjustment was at the bottom of the shock......
ISTR that its a single damping adjustment (ie not separate compression & rebound) - if so, the valving on the fronts versus the rears should already be set up to accommodate the difference in weight (ie you don't need to go twice as hard on the fronts, as it'll already be set up to be twice as hard anyway)
What you'll need to do is experiment on a favourite (and quiet...) piece of road, that has the required undulations and bumps
Set it up full soft and go for a drive - it'll wallow a bit and will tend to understeer
Then, set everything full hard and it'll bounce like Zebedee on speed and the back end will try to step out
now start to find a decent mid point setting, where the car absorbs bumps without pitching you into the scenery, but without more than once "bounce" before it settles
From experience, I'd suggest you start from the soft end of the scale, rather than the hard end, as I think you'll find your eventual settings are closer to the soft end if you're after "fast road", rather than "trackday"
I would suggest that the key attribute to aim for is the ability to hit the power fairly hard halfway round a corner and the only effect is the Quaife will pull you round, rather than tug you off-line. Also desirable is the ability to lift off part-way round a bend without the rear stepping out. A slight correction of line is OK, but you don't want to be adding opposite lock.
Finally, you need to be able to plant the throttle at any speed in any gear in a straight line and STAY in a straight line
If I can get all of this on Osravs and Toyo Proxes, you should definitely be able to achieve it on BCs and AD08s
FWIW, my "sweet spot" is about 20% from soft on the rear and 25% from soft on the front
I'm guessing that the lift off understeer is caused by the fact that you're way too hard at the rear (oooer missus...)
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Re: BC BR Series Coilovers
[Re: Trappy]
#1545546
27/07/2015 12:33
27/07/2015 12:33
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Joined: Feb 2006
Posts: 5,391 Essex
Trappy
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Forum is my life
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OP
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Essex
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I’ve now got the damper strength set to 12 clicks from soft. I haven’t been able to adjust it over the weekend as I’ve been away but I drive it shortly on Saturday morning and it is totally un-driveable. The geometry is so far out that I’m looking forward to seeing the results (you can literally see how far both front wheels are sticking out! On that note, it’ll be going in next Saturday for a full fast road set up.
At the moment, I know the following are adjustable on these coilovers: - Ride height - Bound and rebound (same setting) - Camber
The question for me is does it allow for corner weighting?
F****** b****** thing...
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Re: BC BR Series Coilovers
[Re: Trappy]
#1545547
27/07/2015 13:00
27/07/2015 13:00
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Joined: Dec 2005
Posts: 12,296 Sandhurst
Begbie
ex El Presidente
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ex El Presidente
I AM a Coop
Joined: Dec 2005
Posts: 12,296
Sandhurst
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I believe with corner weighting, that the car is measured at each corner (obviously) and the height, camber and rebound is adjusted to take account the weight over each corner, so the height might be slightly different on one side to the other, along with the rebound hardness.
Your car is Usain Bolt with wellies
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Re: BC BR Series Coilovers
[Re: Trappy]
#1545554
27/07/2015 13:49
27/07/2015 13:49
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Joined: Oct 2008
Posts: 6,783 In the coupe.
magooagain
Club Member 259
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Club Member 259
Forum is my life
Joined: Oct 2008
Posts: 6,783
In the coupe.
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I seem to remember that Kevin 20vt had a big problem with them at first fitting. He reckon the car nearly sent him into a ditch. He wrote about it on here I think on the bc coil over thread.
Edited to add that Kevin started to contribute to the thread at page 10. May be worth a read Trappy. Hope it helps.
Last edited by magooagain; 27/07/2015 13:52.
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Re: BC BR Series Coilovers
[Re: Jimbo]
#1545627
28/07/2015 11:20
28/07/2015 11:20
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Joined: Feb 2006
Posts: 5,391 Essex
Trappy
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Jimbo, I’ve been searching through your old posts but can’t find what I’m looking for. I’m sure you once said that the Coupé should, in theory, handle better at standard ride hide than when lowered. I ask because it rubbed the rear wheel arch again and now I’m happier with the dampers set to 12/30, I’m going to increase the ride height to clear them. At least until I get the rear subframe refreshed anyway as it’s possibly something that worn that’s causing the wheel to protrude a few mill further on the right and so snag the wheel arch.
F****** b****** thing...
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Re: BC BR Series Coilovers
[Re: Begbie]
#1545628
28/07/2015 11:22
28/07/2015 11:22
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Joined: Feb 2006
Posts: 5,391 Essex
Trappy
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I've donme some reading and think I'll wait until I've had the suspension refreshed with poly bushes before having this done. Sounds like it'll be the icing on the cake but not something you can really do if you're going to be fiddling with it all in the near future.
F****** b****** thing...
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Re: BC BR Series Coilovers
[Re: magooagain]
#1545629
28/07/2015 11:23
28/07/2015 11:23
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Joined: Feb 2006
Posts: 5,391 Essex
Trappy
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Thanks Joe. I had a good read through before buying and so am aware of the problems a few people had that were later ironed out in the most part. It's really only the front end that's not up to snuff no and, before the tracking is done, I couldn't really say the coilovers are at fault.
F****** b****** thing...
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Re: BC BR Series Coilovers
[Re: Trappy]
#1545632
28/07/2015 13:34
28/07/2015 13:34
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Joined: Dec 2005
Posts: 17,370 Staffordshire
Nigel
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The reason that the Coupe handles better with standard ride height is the angle of the wishbones
At standard ride height, the wishbones should be angled very slightly downwards towards the wheel hub - this is so that when the suspension is compressed, the wishbone prescribes an arc, which actually moves the hub away from the centre line of the car, and thus increases the negative camber as the suspension compresses
On a lowered car, the wishbones are parallel to the ground, or even angled upwards at the hub. This means that when the suspension compresses, the camber moves towards positive, which isn't desirable
The answer (which is fudging the issue) is to beef up the anti-roll bars, but this has the undesirable effect that uprating the front ARB promotes understeer, so the rear has to be beefed up even more
Quite simply, the Coupe suffers from being derived from the Tipo - it was never meant to be a low-riding, sharp-handling sports car.
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Re: BC BR Series Coilovers
[Re: Trappy]
#1545633
28/07/2015 13:46
28/07/2015 13:46
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Joined: Dec 2005
Posts: 9,706 Gone
Jimbo
Je suis un Coupé
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Je suis un Coupé
Joined: Dec 2005
Posts: 9,706
Gone
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Yep, as Nigel said above, it's the angle of the wishbone that effects the geometry. That said, the movement is so small with uprated dampers and springs that you'll be lucky to see an inch of travel so the geometry won't be changing to dramatically.
One thing I like about these coilovers is the adjustment. The height adjustment on the front is done at the hub mounting so you aren't altering the pre-load on the springs when you change the ride height.
Get the wheel alignment done and set the camber, etc, it will feel a completely different car once that's done. It will be a game of tug-o-war on the steering wheel until it's all pointing in the right direction.
Last edited by Jimbo; 28/07/2015 13:46.
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Re: BC BR Series Coilovers
[Re: Jimbo]
#1545634
28/07/2015 14:04
28/07/2015 14:04
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Joined: Feb 2006
Posts: 5,391 Essex
Trappy
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Forum is my life
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Thanks Nigel / Jimbo. The car is currently sitting 10mm or so higher than it was on the Eibachs so I might go another 10mm higher for now. Nigel, I am thinking about upgrading both ARBs at some point too. I just want to see how nervous it is with all of the planned mods finished first. First impressions of the tyres and suspension at the rear is that it feels VERY planted but we'll have to see. A refurbished rear subframe with poly bushes is also on the list if it is still a bit vagued Jimbo, it's not so much a tug-o-war at the moment, the problem is that the car is VERY keen to steer itself. There is no self correcting what-so-ever. Instead, if it finds the slightest camber in the road, it will just veer off - makes for a very interesting drive!! I only wanted these coilovers because the pre-load was independant of the ride height. Time for a call to Elite then
F****** b****** thing...
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Re: BC BR Series Coilovers
[Re: Trappy]
#1545635
28/07/2015 14:11
28/07/2015 14:11
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Joined: Dec 2005
Posts: 17,370 Staffordshire
Nigel
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Staffordshire
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Nigel, I am thinking about upgrading both ARBs at some point too. Definitely wait until the rest of the setup is done, as I suspect you won't need both, just a rear the problem is that the car is VERY keen to steer itself. There is no self correcting what-so-ever. What camber are you running? Sounds like a proper geo setup will work wonders - you should be able to get it so that its pointy into corners AND planted on long sweepers AND stable on straights
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Re: BC BR Series Coilovers
[Re: Nigel]
#1545637
28/07/2015 14:49
28/07/2015 14:49
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Joined: Feb 2006
Posts: 5,391 Essex
Trappy
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I'll have a look tonight; both at the top mount and the reasoning behind your question in the thread!
Anything I should be worried about?
F****** b****** thing...
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Re: BC BR Series Coilovers
[Re: Trappy]
#1545640
28/07/2015 15:34
28/07/2015 15:34
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Joined: Dec 2005
Posts: 17,370 Staffordshire
Nigel
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Anything I should be worried about? LOL - if you have the asymmetrical top mounts AND you fitted them so that the centre of the shock was forward of the centre-line of the mount, you would have reduced caster quite significantly, which would reduce the self-centring effect of the steering
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Re: BC BR Series Coilovers
[Re: Nigel]
#1545644
28/07/2015 16:04
28/07/2015 16:04
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Joined: Feb 2006
Posts: 5,391 Essex
Trappy
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From memory (5 minutes last Wednesday) the L one has been installed on the left and the R on the right but I'll check tonight.
F****** b****** thing...
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Re: BC BR Series Coilovers
[Re: Trappy]
#1545645
28/07/2015 16:10
28/07/2015 16:10
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Joined: Dec 2005
Posts: 17,370 Staffordshire
Nigel
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the L one has been installed on the left and the R on the right Logical, I guess..... If they are "handed" I believe it means you have the asymmetrical versions, which is the version that gives you higher castor and stronger self-centring
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Re: BC BR Series Coilovers
[Re: Nigel]
#1545646
28/07/2015 16:21
28/07/2015 16:21
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Joined: Feb 2006
Posts: 5,391 Essex
Trappy
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the L one has been installed on the left and the R on the right Logical, I guess..... Depends which way you're looking at the time... I get so sick of the looks I get at work when I ask for specifics that I give up when it comes to the hobby... to my detriment mostly... If they are "handed" I believe it means you have the asymmetrical versions, which is the version that gives you higher castor and stronger self-centring
So I have the ones that give more castor if installed correctly, but less if not? I'm Rog knows what he's doing.
Last edited by Trappy; 28/07/2015 16:22.
F****** b****** thing...
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Re: BC BR Series Coilovers
[Re: Trappy]
#1545732
29/07/2015 13:16
29/07/2015 13:16
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Joined: Dec 2005
Posts: 17,370 Staffordshire
Nigel
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I'm thinking there may be a cock-up with the labelling on the top mounts Firstly, you definitely have the asymmetrical mounts - you can clearly see that the opening for the shock is forward of the outer mounting, whereas on Begbie's, they are in line - see below However, the aspect that's throwing me is that SURELY, the idea of the asymmetrical mounts was to increase the castor, not decrease it.... I think a question needs to be asked of BC as to the reasons for the two versions of top mounts - if they say the asymmetrical versions are to give more castor, then they've got the labels on the wrong side of the mounts I wouldn't alert them to the fact there's a possible issue - just ask why some top mounts are symmetrical and some are asymmetrical
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Re: BC BR Series Coilovers
[Re: Jimbo]
#1545738
29/07/2015 13:57
29/07/2015 13:57
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Joined: Feb 2006
Posts: 5,391 Essex
Trappy
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So it may just be that BC have labeled all of them the wrong way around? It isn't just light Jimbo, it turns itself. There's no weight to it at all! I'll have to have a word with Rog then as there's no way I can do this myself. I don't even have tools or a jack anymore
F****** b****** thing...
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Re: BC BR Series Coilovers
[Re: Nigel]
#1545799
30/07/2015 09:22
30/07/2015 09:22
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Joined: Feb 2006
Posts: 5,391 Essex
Trappy
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Good stuff, Nigel, I look forward to the response!
F****** b****** thing...
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Re: BC BR Series Coilovers
[Re: Nigel]
#1545806
30/07/2015 11:41
30/07/2015 11:41
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Joined: Feb 2006
Posts: 5,391 Essex
Trappy
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I also found a post from Kevin_20vt as follows… Castor... Looks like it was well know back then. I foolishly made an assumption that these were teething problems that were later resolved. Maybe I could get away with having them swapped over?
F****** b****** thing...
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Re: BC BR Series Coilovers
[Re: Trappy]
#1546192
04/08/2015 13:17
04/08/2015 13:17
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Joined: Dec 2005
Posts: 17,370 Staffordshire
Nigel
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I've had an answer, and suspect that a) Apex don't know Coupes well enough to comment and b) the factory has made a mistake
Hi,
Please see below explanation from the factory:
We used to think that ZO-01 front top mounts were symmetrical, however, last year, there came a 93 coupe to our factory and we now know that the front left top mount is a tiny bit offset, so we modified the design of top mounts after then, hope this helps you clear things up.
Regards, James
Apex Performance Parts Ltd +44 (0)1274 683633
I don't accept this explanation, so I have replied with the following:-
Hi James
There are no ’93 Coupes in the UK – the earliest is May 1995. A 93 Coupe will be a very early LHD model (very few were registered in 93). In any event, the vast majority of your customers will own 20valve turbo Coupes, which are late 96 onwards.
The factory explanation doesn’t make sense, as on some of the kits you have supplied, the topmounts are symmetrical and on some kits BOTH topmounts are visibly offset (approx 1cm at a guess), not just the nearside. If it were the case that only one topmount is offset, then every kit you have supplied is incorrect.
I find it difficult to believe that the factory would amend its production specifications based on their findings from a single early left hand drive model, especially when the later 20v models account for about 90% of the Coupes still on the road in the UK.
Standard 20v / 20VT topmounts are ‘handed” with a slight offset to the REAR of the car.
The problem is that the offset on your “handed” topmounts has been set forwards, which is dramatically reducing castor and causing unusual handling characteristics – one customer is reporting zero self-centring effect. Even your symmetrical topmounts will be reducing castor over a standard car
For the record, I have no vested interest in this matter, as I haven’t purchased any BR coilovers for my own Coupe. I am merely getting involved as a Coupe enthusiast, in an attempt to assist those Coupe owners that have spent their money and are suffering handling issues.
Given the unusual handling traits experienced when castor is dramatically reduced, I would respectfully suggest that this matter is given the urgent attention is deserves, rather than wait for an owner to have an accident.
Regards
Nigel Ogram
I'll await their reply and post it back here, but I rather think that one of the current BC coilover customers needs to take this over from me.
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