Best hopups for MR4-BC

[kriss]

Hi there,
Getting a MR-4 BC for xmas and just wondering if anyone has any advice on which hop ups are worth getting. Ive been told the aluminium threaded shocks are good. If anyone could give me a price for the shocks i would be greatful.

Cheers Kriss

[nitro-head]

i have seena lot use the associated buggy shocks, a lot smoother i think.

i am guessing its the normal one.

i suggest your first thing to do is ball race it, then look at other things.

[kriss]

Thanks.
Just wondering if you own one and if you have a setup sheet for it

[sosidge]

You're not Chris Bell from Oxclose are you?

[nitro-head]

i used it at the interclub (for the north) is one heat as my xxx-4 was under repair

it went well, i got it 2nd hand off ebay for 60 quid with ball races in, front one way and quite a few spares.

make sure when you are building the diffs that it has shouldered diff screws, if not, get some and put them in as your are building it.

[BC Rog]

The best hop -up is the Special kit. Seriously, ther is so much different in ££££ terms that your better off...... especially if you get one from Doom Cars Racing.....!!!!!!

I'm over the moon with mine. Std SP. except for the Associated shocks, B4 fronts and B4 rears with 1.32" shafts in. That is all that is requried. Ok I have a few other mods but they are all personal choice set-up stuff.

Car is exceptional!!!!!!!

Rog

[JV]

Hi.

Well, I've just aquired an SP kit, but like you it'll probably be Christmas before I do much with it.

Apart from reviewing the postings in this forum, you could look at sosidge's webpages ( http://www.sosidge.pwp.blueyonder.co.uk/index-page2.html ),
and check out the yokomo usa website & forums.

When I've got a couple of hours of not being knackered I'll be going through this stuff again for my own benefit. I'll post a summary of what I come up with. Don't hold your breath though.

The SP does appear to come with competant shocks (I obviously haven't tried them), but there seems to be a bit of an issue with springs for them.

And wheels seem a bit hard to get hold of. The SP comes with nice wheels, but has weird wheel fittings. I'm after another couple of sets. If all else fails (or if UK prices turn out to be truly silly) I'll try to get one of my colleagues in the US to order some, & bring them over in January. But that's probably best discussed offline.

John.

[Andy Taylor]

Hi there,
Getting a MR-4 BC for xmas and just wondering if anyone has any advice on which hop ups are worth getting. Ive been told the aluminium threaded shocks are good. If anyone could give me a price for the shocks i would be greatful.

Cheers Kriss


Shocks from an associated B4 with 1.32 rear shock shaft and the front standard shocks from a B3 or B4 will make it handle correctly. European champion says so and the car was awesome with his set up.

The Standard BC though is very different from the BC and to be fair it will cost more to upgrade than buy it from the start....now you have one you did not want to hear that did you :)

Where are you going to be running the car??

[mike.stening]

The associated front shocks are actually no better than the Yoke threaded ones, its seems to be the rears that make the difference (even though i have been told that the yoke threaded shocks are actually made by associated)
you can buy the associated spring sets for front and rear and fit them to the yoke shocks. i personally like the yoke ones and have used the B3 shocks (fronts same as B4 rears have longer bodies than the B4) which were on my MX4 and then on my BC SP. the Yoke ones are super smooth.
You could consider the shock bladders but you would need the shock caps to fit them too.
upgrading from a standard BC to the SP will cost you, i converted my MX4 to a BC SP and it cost more than buying a full SP kit in the long run but at the time the SP wasnt avaliable.
Another thing worth considering is MIP CVD's (the MX4 ones) if you can get them.
Some people like the front one way others dont, personally i like it.
ther are other options but it really depends on your budget.

[JV]

Mike Stenning Writes:
> the yoke springs are actually 2 different rates
> but the same colour purely for aesthetics.

Not saying what the spring rates are is a bit too cranky for me.

> The associated spring kits fit

Aha. You're saying the AE front and rear buggy springs fit the yokomo
front & rear shocks, right ?

AE seem to do nice sets of springs with a series of spring rates.

I think I'll see how I get on with the Yokomo shocks and the AE springs.


Do AE sell the shocks as pairs of complete shocks ? I had a look at their parts lists, because the folks here keep on about the AE shocks, but I got a bit lost in a sea of shock components.


> The Sp comes with a layshaft oneway,
> but I have also been running it with a front oneway as well

I'll see how I get on with the centre one-way to start with.

John.

[JV]

Are parts interchangable between AE and yokomo shocks ?

As I understand it, neither the AE nor Yokomo shocks has fancy features like damping that varies with travel, or different rebound and compression damping, so there don't seem to be many variables left to distinguish them.

The number and size of holes in the pistons seem like the main candidates.

[cobra81li200]

If you buy a BC, go for the YMP conversion kit and you'll have Masami's Ride... almost... muhuhuhahahaaa

[sosidge]

Are parts interchangable between AE and yokomo shocks ?



Hi JV,

The Yokomo and associated shocks are different - essentially because AE use imperial measurements, and Yokomo use Metric.

Now, the Yoke shocks are like Metric "versions" of the associated ones - lengths of bodies and shocks are the same for example, so you get the same travel if you switch over from one to the other. The old screw-on Yokomo caps with a bleed screw fit the associated shock. The associated shocks fit properly on the Yokomo shock mounts and screws. Seals, pistons and shafts are different sizes though. Springs are also a smaller diameter - they will fit around the Yoke shock, but you need to to a little trickery with the shock bottoms to get them to sit right.

[BC Rog]

I did a post with a spring chart covering ALL the main off-road manufactures. Have a look for it as I can't remember where it was posted!!!!

I can e-mail it to people who are interested.

I'm sure that Dom will produce a nice laminated version for a reasonable price if anybod is interested ..... don't worry mate, I expect no royalties ;)

[mike.stening]

i believe Rayspeed do some nice blue anodised shock bottoms that allow the fitting of the associated springs, they are intended for the TC shocks but as the sizes between the BC and TC seem to be the same in many cases they should fit no probs.

[mike.stening]

also the YMP conversion kit is basically the MX4 front shock tower with the relevent parts for it to fit, like the bulk head and A arm plate mounts etc.

[kriss]

Can you buy the shocks off the special MR-4 BC or are they unique to that kit also would they fit the normal MR-4 BC?

[Doomanic]

Yes, they are available seperately.

[kriss]

will they be smoother than the normal one and how much is it going to cost me?

[Doomanic]

They are exceptionally smooth.
Price is around £30 per pair.

[JV]

BC Rog writes:
>The Yokomo shocks are far better build quality than the AE ones
> but they got their sums wrong!!!!!

> There is too much oil in the rear shocks and that leads to much pack,
> worse still the level of pack changes drastically durring the stroke !!!!!!!!!!!!!

Eeek! I've searched through my copy of "Motor Vehicle Dynamics for Dummies"
and I still don't get it ;-)

What is this "level of pack" of which you speak ?

Are you talking about the shocks getting pumped down over a series of bumps ? Nah. Doesn't make sense.


Mike Stenning writes:
> You could consider the shock bladders but you would need the shock caps to fit them too.

Or the oil getting aerated ?

[sosidge]

Pack isn't having the shock pumped down over a series of bumps (I believe that effect is called "jacking" where the shock doesn't recover enough from a bump, and the car gets ends up losing ride height after a series of bumps).

Pack is where the piston stops flowing though the oil smoothly (something to do with laminar and turbulent flows). A smaller piston hole will "pack up", and stiffen the damping, before a big piston hole does.

[JV]

sosidge writes:
> Pack is where the piston stops flowing though the oil smoothly (something to > do with laminar and turbulent flows).

OK, so it does sound like we're talking about the fine details of the pistons.

Somewhat theoretically, it seems like the shape of the edges of the hole could make an order of magnitude or more difference in the Reynolds number at which turbulence starts.

> A smaller piston hole will "pack up", and stiffen the damping,
> before a big piston hole does.


I still don't get what Rog was on about when he said:
> There is too much oil in the rear shocks and that leads to much pack

The total ammount of oil doesn't seem to me to relate to anything much.

Whatever. I think I've dug into this about enough for now. Time for some experiments.

Regards,

John.

[BC Rog]

JV ...

I had a problem understanding it at first but it isn't too complicated when you can put the simple piston / damper theory behind you (where it should be at anything past A-level..)

As the piston moves through the oil the volume of oil on each side of the piston changes (obviously) relative to each other. Now think about the density of the shock shaft compared to the oil ..... as you get more shock shaft in the oil under the piston you are actually displacing total mass than the oil being transfered across the piston (again abvious).

The problem comes when you consider that none of the shocks we use are truely "volume compensated". The overall effect of this is to cause a change in the relative pressures either side of the piston. This will lead to the coefficent of discharge (how much oil can flow through each piston hole for those that have lost me slightly) decreasing slightly and "packing up" the shock. The way around this is to run the shortest travel you can (hence the short B4 body and longer shaft) and also to keep the nominal piston position near the start of the travel. If you can work it all through properly the shocks should never go much over 75% of there travel in normal use, leaving the end, slightly packed travel to deal with the big stuff.

This packing effect can be useful on jump landings though so don't go too far.

The other way around this is to run a pressurised shock so that the change in pressures through the travel is neglible compared to the base pressure in the shock. That is why "Gas shock" (ie. nitrogen filled bladders pressurising the oil) in full size cars help both handling and ride!!!!!

Rog