Rose Jointed Arms - Too Many Choices?

[wildejon 7]

I had a chat to a well known 205 expert on here and plan to grab a pair from him this week.

I've just been talking to a friend though who suggested I ought to shop around, everywhere else seems rather pricey though.

 

Had a look on here and found there are tons of options and pros and cons and now I feel rather confused.

Con's seem to be that they aren't as safe as standard, any facts? Pro's seem obvious though.

 

I guess my reason for posting is just looking for an increase in confidence that I'm doing the right thing!

Car is mainly for road use initially, track use later provided I get around to it eventually.

 

Thanks

Edited February 22, 2010 by wildejon

[Baz 421]

Rose jointed where? Inner and outer or just the outer/BJ replacements?

[wildejon 7]

Good question! Just the BJ replacement.

[brumster 135 1 Cars]

I run PTS pattern arms manufactured for Andy at AB Motorsport to his spec, these use standard inner bushes and the rose jointed outer. Most of the cost is in the joint itself - from memory these are the best part of £90 each just for the joint - but considering the load they withstand, and the abuse out on stage, you just can't scrimp. I've heard of people using cheaper spherical rod ends and the outers basically destroy themselves after a couple of stages.

 

My arms have been on the car for the best part of 9 years now, and I've only had to replace one rod end during that time due to wear. If I'm hurtling through forests or tarmac roads with trees or drops either side, I don't think I'm worried about safety somehow

 

From what I've been told, I wouldn't bother with rose-jointed inners unless you're doing serious smooth track work. Not from experience - I've never bothered with them - but I've heard of troubles with them breaking, I guessed due to the transfer of forces into the subframe and no "give" in them? Probably ok if they're not going to get any bangs, but I have no interest in testing that theory out! And don't be tempted with nylon-style inner bushes either, I was going to go this route until Andy warned me that they don't last at all and the standard Peugeot bushes are far more cost effective.

[wildejon 7]

Thanks, that is really helpful!

[Cameron 16]

Standard Peugeot bushes are more cost effective but say hello to Mr Compliance ruining your suspension geometry. Even though the polybushes wear quicker, they're definitely worth fitting.

 

I think the problem with using rod ends for the inners is pretty well covered in my thread "Tubular Wishbone Project" in this forum. Basically the rod ends need to be seriously beefed up due to the forces acting on them, otherwise they're just gonna bend.

[brumster 135 1 Cars]

Standard Peugeot bushes are more cost effective but say hello to Mr Compliance ruining your suspension geometry. Even though the polybushes wear quicker, they're definitely worth fitting.

 

I'd need convincing of this (not trying to be argumentative, though, bear with me)... while it makes sense that a piece of rubber is going to bend more than a piece of nylon, are the effects on those inner wishbone mounts all one might think they would be?

 

With most things like this, I tend to look at what the likes of front-running rally 205's run - because they're clearly competitive, it's a good indication that if it works for them it's a safe bet to go with the same. And the way AB's car tackles Epynt I don't think he has any concerns about compliance in his front end !

 

However, I will admit one thing - stage rallying is not road driving, circuit racing, sprinting or track daying, so the comparison is only fair in a like-for-like situation, I guess. I'd be tempted to try nylons out on the front just to see if they make all that difference, but I'm always disuaded by the advice of someone who's been there before, tried it and tells me not to bother!

Edited February 23, 2010 by brumster

[Cameron 16]

Well, no.

 

The effects will be quite small as the rubber part of the bush isn't all that thick, but it will be an effect nontheless. The forces generated by cornering will be trying to push the bottom of the wheel inwards and the rubber bushes will allow it to do so and create a small amount of positive camber, which isn't what you want for any kind of driving!

 

I'm sure there are cars that are competitive with them fitted though! I'm not saying they're an absolute must, but it definitely makes sense.

[brumster 135 1 Cars]

Sure; I understand. I think what I was trying to say was on stages, you probably have to weigh up the need for that additional compliance with maintenance costs, plus (if it would be any issue? I don't know - you probably have a much better understanding, from reading that wishbone thread!) is some sort of 'give' in those inner mounts worth keeping in the event you clonk a kerb/rut/stone/etc, and trade off the loss in compliance with slightly better reliability in harsh environments?

 

I dunno, I'm spouting stuff off the top of my head now

[Tom Fenton 1,526]

In my opinion they do not make sense at all for a gravel car, that sees shock loads well in excess of anything a tarmac circuit car will see.

 

In the gravel car I'd go for some compliance every time, rather than a rose joint or spherical bearing that is admittedly stiff, but could potentially smash in high impact loading. This could be the difference between limping to the end of a stage, rather than stopping shortly after the impact.

 

Speaking from experience spannering my mates 205/309 rally cars.

[philfingers 5]

I have West Mids Motorsport arms, similar price to AB's that Brumster uses.

I priced a joint recently, £112 + vat and delivery, you're looking at £130 each, the pins are about £60 a pair I think and std pug bushes for the inners are £17ish a side, so there you go, £355 just for the uprated parts.

Throw in the price of either new or used arms for conversion and you can see why they're £550 a pair.

Any cheaper than this and be wary. The correct rosejoint is M20 thread with an m16 hole for the pin from memory.

RBJ79MG i think is the part number

 

in fact here is the quote:-

 

RBJ79MG X 1 @ £110.63 each STOCK

Rubber Boot for above X 2 @ £2.40 each STOCK

GE25DO X 2 @ £9.64 each STOCK [top mount bearing]

 

Carriage options

 

1st Class Post @ £4.99 (at customers sole risk)

OR

R.M.S.D. @ £6.85 (guaranteed before 1pm next day)

 

All +vat

[Cameron 16]

Sure; I understand. I think what I was trying to say was on stages, you probably have to weigh up the need for that additional compliance with maintenance costs, plus (if it would be any issue? I don't know - you probably have a much better understanding, from reading that wishbone thread!) is some sort of 'give' in those inner mounts worth keeping in the event you clonk a kerb/rut/stone/etc, and trade off the loss in compliance with slightly better reliability in harsh environments?

 

I dunno, I'm spouting stuff off the top of my head now

 

Yeah absolutely, the give in a bush will mean it will cope with all the vibration a lot better than a solid rose joint, so unless you can afford to replace a spherical / RJ every event or so they probably aren't worth using. However they would be much happier on track.

[Baz 421]

In my opinion they do not make sense at all for a gravel car, that sees shock loads well in excess of anything a tarmac circuit car will see.

 

In the gravel car I'd go for some compliance every time, rather than a rose joint or spherical bearing that is admittedly stiff, but could potentially smash in high impact loading. This could be the difference between limping to the end of a stage, rather than stopping shortly after the impact.

 

Speaking from experience spannering my mates 205/309 rally cars.

 

Seconding that, i have the fully RJ'd ones, great for a smooth tarmac track/race but i wouldn't put them on a rally car tbh.

 

Pretty sure even the GpA stuff was still using standard bushed inners with a Rose-joint BJ end, as brumster said. This is what a lot of the rally guys use too, so i'd be happy to use these for more all-round usage etc, as i'm pretty sure these are what you're talking about Jon, and they're very well made too, if they're coming from where i think they are!

Edited February 23, 2010 by Baz

[Rippthrough 98]

From what I've been told, I wouldn't bother with rose-jointed inners unless you're doing serious smooth track work. Not from experience - I've never bothered with them - but I've heard of troubles with them breaking, I guessed due to the transfer of forces into the subframe and no "give" in them? Probably ok if they're not going to get any bangs, but I have no interest in testing that theory out! And don't be tempted with nylon-style inner bushes either, I was going to go this route until Andy warned me that they don't last at all and the standard Peugeot bushes are far more cost effective.

 

 

As Cameron says, it's explained quite nicely in his tubular wishbone thread, basically, most manufacturers are loading the rear rose joint the wrong way and eventually fatigue + shock loading makes 'em go snap.

The same can happen with nylon if you're not using one of the softer, more compliant bearing grades such as nylube too - they tend to split in an impact.

 

Anyhow, for a gravel car, a well designed tubular wishbone would be fine, the give in the tyre is enough to take out shocks, and even hitting rocks/etc. with the rim is more likely to damage the alloy than the wishbone, hell we use rose joints on the tie rods on the safari cars, and they might be banging off rock lined walls of a 6ft wide track whilst in 2 foot deep ruts...and there's plenty of competitor cars running jointed for the gravel events at Sweetlamb and Bleddfa.

Ok, we do run poly in the inner wishbone bushes, but that's mainly because were quite often bouncing the face of the wheel off a banking/quarry wall - and our wheels are a lot stronger than a typical gravel wheel.

The problem there is, bar the KRS ones, I wouldn't say there's many on the market that are well designed, so up until then, the PTS style ones probably are your best bet.

Edited February 23, 2010 by Rippthrough

[wildejon 7]

Thanks for the help guys, appreciate the advice!

[wildejon 7]

Hi all,

Just assembled my lower arms, not sure if the gap between the top of the vertical bolt and the hub is OK or not. It is fairly tight, although not on the car so I can't get the leverage to go crazy. Doesn't seem like I have much of a choice anyway, reckon it'll be OK?

Linky

 

Thanks!

[Dazza 4]

Lokks a little tight Jon , albeit do the pins have a bevelled edge as to avoid the drive ahofts ?

[wildejon 7]

They do, yes. I don't, think it will sit any flatter than it is though. Not checked to see if it will foul on the drive shaft yet, just want to be certain it's not going to fall off

I could take a little more off the top of the pin if I have to...

[Cameron 16]

I'd be a bit concerned about that.. You might want to grind an angle into the bolt shoulder to clear that radius on the hub. Looks like another element of Compbrake's poor design.

 

Edit: don't be tempted to grind into the radius on the hub though, it's there for a reason!

Edited February 27, 2010 by Cameron

[wildejon 7]

Right then, I've had a crack at that bolt.

Would someone mind taking a look and seeing if its OK?

Link to flickr which I'm finding really annoying to use!

 

I think the fit is a little better but I'm not sure if I've gone a bit too far with the bolt and also whether I need to treat it before I fit it now?

 

Thanks!

[205wrc 16]

Looks like you're missing the "Top Hat" spacers from there. These allow you more movement / clearance between the rose joint and the hub. Without these, your rosejoints will probably hit the hub when your suspension is at full droop

 

 

 

[wildejon 7]

OK, thanks for that. I'll take a look. The bolt is barely long enough as is though, I couldn't fit anything else in there...

EDIT: It's cool, the spacers are present and correct, phew!

I notice your bolt heads are like mine were anyway! lol

 

Any thoughts on treating the bolts or if they are ok as they now are?

Edited March 5, 2010 by wildejon

[205wrc 16]

The bolts that I use are the same as the PTS ones, available from AB Motorsport, Skip Brown or J.S. Engineering, who made them for me. They are made from EN24 grade Steel and are the same material as your average wheel bolt.