Raceleda Uprights On L/w

[Guest ScotMac]

My customization of my l/w is again creating problems for me!!

 

While playing around w/ my front suspension, i noticed i have way too little travel....slight problem.

 

The problem is that i switched from the normal Sierra to MNR/Raceleda uprights. RH supplies a dummy strut (mushroom adapter) to go w/ the Sierra uprights for the l/w, just like the 2b (well they do if you pay a bit more, actually). That dummy strut has the balljoint hole positioned towards the outside, and, more importantly, it has a built in slope on the top of it, away from the car. This angle/slope and positioning, combined w/ the geometry of the bones, allows the top balljoint to operate at a good angle, thus allowing it a good range of movement. Well, the Raceleda uprights were made for locost'ers, who make bones for the *standard* sierra angles, not this RH derived one. Hence, the top balljoint very quickly runs out of travel.

 

I could obviously go back to the Sierra upright, but at double the unsprung weight, it is not desirable (besides the 650gbp's i paid for the front-end-kit!! ).

 

I could somehow adapt the top of the upright, but i haven't really figured out a good way to do it. I could also bend the w-bone, but that is not very appealing. I am having trouble coming up w/ good solutions.

 

Here is a photo showing the issue:

 

[Guest ScotMac]

Hmmmm,...something like this would work:

 

http://www.locostbuilders.co.uk/viewthread.php?tid=40423

 

W/ a tapered bolt on the bottom of that adapter, instead of the mushroom insert. I'll have to check w/ MNR, and see if they have any standard adapter for this. If not, i better start figuring angles for the adapter.

 

So, the adapter should the have the same angle as the KPI on Sierra uprights, right? Assuming the top bones are fairly horizontal...which they are, as can be seen in the photo....tho the adapter would take it up a bit more, and make the bones less horizontal.

 

Guess i could always switch to some high misalignment rod ends, but i prefer the strength/longevity of a balljoint.

[Grim]

could you not cut and weld the ball joint threaded section?

[Guest gdc]

hi scott

is it poss to have the top of the upright machined to give more movement ie with radius on the top of the upright, if the material is thick enough it could work.or am i not in the right area?

regards graham

[Guest ScotMac]

Yes Grim. In fact, don't they make non 90deg angle balljoints (effectively the same thing as what you are proposing)? I have never seen nor heard of one, and search of the web doesn't reveal any, but i would think someone (me) would need such a thing...anyone seen them?

 

Graham, I had thought of that, but didn't think it would be a win, unless i also changed the angle that the bolt fits thru the top of the upright to match the newly ground down top of the upright. However, you are correct, just removing some of the material will give me some move movement, since the BJ is obviously fouling on that material when it runs out of travel. Only negative is that it weakens the support for the taper. The upright is aluminum, but the taper is a separate insert at the top (and bottom) of the upright. This taper insert is atleast partially being supported/stabilized by the about 1/4" lip it has on the top of the upright. If the material to be machined was just all part of a one piece upright, it would make the machining much easier to comtemplate.

 

However, the fact that there is a separate taper insert leads me to hope that MNR has sometype of different insert to help me w/ this...yes, i know, wishful thinking...but a guy can hope.

 

Thanks for the replies.

[Guest old_timbo]

A couple of thoughts:-

 

I've seen people using rose joints instead of ball joints. Would they give more travel? You would have to make up a new fitting to go into the upright.

However have you moved the suspension through its whole travel and studied how the camber angle changes? On the 2B with the standard 'dummy strut' which ends close to the top of the upright the supension builds negative camber as the suspension extends, instead of building postive camber. In a corner, this means that as the car rolls the outside wheel ends up just on its inner edge causing understeer, rather than the camber angle change compensating for the roll and keeping the wheel perpendicular to the ground. On a 2B, making the dummy strut about 80mm taller (about as far as you can go without causing other problems) makes a big difference (still not perfect). Naturally the top wishbone is no longer parrallel to the bottom (slopes upwards) and also needs shortening by about 20mm, but the ball joint angle also changes and in your case this would cause it to come back closer to the mid postion and give you back the travel you need.

[Guest salty_monk]

I was thinking of Grims idea too. Mind you if you could get a different insert for the upright to change the angle that would do it too. Can you press the one that in there out so you can see what you are dealing with? You should be able to get a pair made up to spec at a machine shop then changing the angle & press them back in. hopefully the insert is big enough so you have room without machining the upright. If this is the case I think I'd attack the bones.

 

It would be pretty hard to get a ball joint with a lot more travel, I think it would need a whole different shape.

 

I don't *think* rose joints would offer you any benefit.

 

Dan

[Guest ScotMac]

Thanks for the replies.

 

Timbo, yes, "high misalignment rose joints" (misalignment heims), which are definitely available, would give me greater travel. Not sure it would be enough, though. And, as you mentioned, i would have to fabricate the "pin". Also, i like the robustness of balljoints. Even the proponents of heims recognize that balljoints will take more abuse and last longer.

 

In terms of the camber, Timbo, it is a very good point. The Raceleda uprights are actually already taller than the standard Sierra...but only about an inch taller, not 80mm's!! Seems like a lot. I have looked at the movement, and i believe i currently gain a tiny bit of positive camber during shock compression, but i need to look at it more.

 

However, it is definitely true that raising the BJ connection point up would change the angle in the direction i need. I thought about it. In fact, an adapter, similar to the one shown on that locostbuilders link, would raise it some, and partially alleviate *some* of the problem for that reason alone. The only problem is, i don't have room on the wishbone. ie, if you look in the picture, at around zero camber, the BJ is already screwed in pretty much all the way into the bone. If i move the contact point up, along the KPI axis, i would move the BJ closes to the chassis/bone, and would run out of space. I could cut a bit off the end of the bone, but i dont think even that would give me enough room. I guess i could go *straight* up, instead of along the KPI line, but that would change the KPI. And i have become much more enamored w/ the Sierra KPI, since i think it will give me a pretty good scrub.

 

Dan, yes, i believe a machine shop might be able to help me out here. In fact, i know of one that specializes in race cars in San Carlos (about 1 mile from me...small towns!!). The insert is basically some type of cylinder, w/ a tophat style flange on top. I believe it is threaded into the aluminum at the top of the upright (i assume it is stainless, otherwise my uprights might not last long!! ). Shouldn't be too hard to get it out. Just has a little pin to stop it from rotating out.

 

I just got an email reply from Marc (MNR), and he says that they have many different inserts for the uprights. I have pointed him to this thread. Hope to hear back from him tomorrow. Got my fingers (among other things) crossed!

 

-Scot

[Guest old_timbo]

Scot, the suspension should build negative camber on compression, so if yours builds a bit of positive then it needs looking at. I had to shorten my wishbones but it looks like I had more to play with than you do. The Sierra upright KPI worked well for me too. Here is shot of my extended dummy strut. Richard at GBS made them up for me to try out. I've seen similar on several different 7's so I presume its a recognised problem.

[Guest ScotMac]

Timbo, yes, that is what i meant. I always mix up neg and pos camber. The top goes in a bit on compression, so yes, a bit of negative camber. Probably not enough though.

 

So far all MNR (Marc) has suggested is mod'ing the bones...not helpful. I am going to try gettting the top adapter out tonight...hopefully can post pictures later.

 

Going to try taking them to the race-car fabrication shop.

 

Cheers, -Scot

[Guest Stevieshood]

Its useful you should bring this topic up, because I have just been considering the MNR upright kit to go with my 2B wishbone conversion kit from GBSC. However, I've realised that the wishbones are too far apart to be able to use the new upright without an extension piece, and modifying it would produce a very high bending moment on the top of the upright, which could have disastrous consequences!

 

The best compromise I can see is to buy the (bling) hubs at £175, because they weight a fraction of the standard ones, and fit directly to the Sierra uprights. Apparently, they save 2.1kg per side, as opposed to the upright, which only saves 0.5kg (according to MNR, although that surprised me). I can then have a crack at lightening the Sierra ones. Also, I can still reuse my Sierra discs and calipers, until I can afford Wilwood ones

 

The only thing that worries me a bit about the 2B kit is what sort of Ackermann I end up with, as the hubs are back to front compared to the Sierra, and the rack is in-front of the axle line with extended tie rod ends. I think I'm going to work this out before I start welding bits on!

[Guest old_timbo]

Just been and checked in my Haynes Sierra manual, actually the rack is in front of the uprights on a Sierra so the 'arms' are correct to get Ackerman effect. Also took a look at the hubs on my 2B and you can see that the geometry is OK. You can vary the amount of Akerman by varying the toe in / out. With the Sierra set-up it should be paralell to a max. of 2.5mm toe out. Its something that needs experimetation - too little and you get understeer, too much and you get instability under braking.

 

Tim

[Longboarder]

wishbones are too far apart to be able to use the new upright without an extension piece

Move the wishbone mounting points closer together, probably by lowering the top mounts, to get rid of the 'parallel' arms problem. You should be able to do this if you are installing the kit. Final wishbone angles with the car at correct ride height should be about those below.

 

Nigel

[Guest Stevieshood]

Thanks for the info guys. I was at work and couldn't remember where the rack was, so did a search and found a pic showing a "Sierra" engine bay with rack bolted to the bulkhead (it looked like a Sierra engine bay at least - its so long since I saw one )

 

On reflection, I should have remembered it was bolted to the subframe with the steering knuckle taking it to the bulkhead. Doh! At least the Ackermann shouldn't be too much of an issue anymore. In fact, alot of rwd race cars with downforce, and some road cars (Lotus Esprit) run "parallel steer" without detriment to the grip, provided you're not racing around saloms courses.

 

Nigel, I was thinking the same thing about the top inboard mount, but even if I moved the holes a bit lower in the new crossmember that comes with the kit, I still can't get it low enough or do anything with the rear mount. Its a bit frustating but I guess its something I'll have to live with.

[Guest ScotMac]

OK, i figured it out. Chalk it up to my inexperience w/ balljoints, and MNR messing up. The issue is, the Raceleda/MNR tapers are not made for the RH l/w balljoints. The taper for the top balljoint allows the balljoint to extend into the upright a *bit* too much, thus restricting the movement. The taper for the bottom balljoint is worse. I can understand MNR's tapers not fitting the top, since there is no stock top balljoint. But the bottom BJ is just sierra standard, which i verified w/ my old sierra uprights. Since this is supposed to be a "Sierra replacement upright kit", the tapers should match sierra balljoints!! I have sent off an email to Marc/MNR to see if he can get me the right taper inserts.

 

The interesting thing is that the taper for the bottom, though it doesn't at all work w/ the bottom BJ, works well for the top balljoint. ie, it is smaller than the one MNR said i should use for the top balljoint, and thus allows the necessary room.

 

Thus, i am swapping the bottom taper to the top, and am trying to get a taper for the bottom. I have talked to a machine shop, and they will machine two for about $200. Not too bad.

 

The angle will still not be great (the original issue i brought up), but i think w/ the better tapers, i will have enough travel to deal w/ it (hoping).

 

Thanks for the help everyone.