MR4BC Ackerman length

[Chrislong]

Messing with my steering and one thing I haven't experimented with yet is the lenth of my Ackerman.

Measured mine it at 45.5mm centre of hole to centre of hole at the moment.

What does everybody else use?

If I remember rightly shorter = sharper steering, and tiny tweeks make a huge difference. Am I right?

Chris

[BC Rog]

Chris,

what are you trying to achieve? Maybe I can suggest a less radical change that will provide what you are looking for.

I moved mine around a bit when I first got the car and settled on the original kit spec (must be a first for me .. :D)

Basically the closer the steering-link ball studs on the ballcranks the more aggressive the car will feel. The further apart the more mellow the car will feel.

The difference the adjustment makes increases the further from parrallel the bellcranks end up at full lock. Basically a small adjustment leaving the bellcracks nearly parrallel will make a subtle difference. It's not linear either so small adjustments are the way to go!!

My advice is that if you feel that you need a longer steering link is to move the ball joints inwards on the bellcranks rather than make large adjustments.

If you play with moving the ball-stud position and plot the angles the steering knuckles end up at full lock ... might be a shock!

Try by all means but I suggest parrallel bellcranks and using the out-board holes!!!

[Chrislong]

Im trying to acheive more aggresive steering without loosing the stability and predictability. The car does not turn in at speed at entry of corner enough for me, but holds grip fine through and out of the corner.

I know you know a hell of a lot Roger, so will give you run down of my setup incase you can suggest something:

7 degree castor, alloy uprights and hubs, MR4TC alloy steering bellcranks, associated carbide balls, alloy front and rear outdrives, long wheel base, 2 degree rear toe in, 1 degree castor all around, camber links all in kit position except out hub is on upper/inner most hole, hubs on middle hole rear, and lower hole front (raising hub against wishbone), associated B4 shocks (still with associated ballstuds) 1.32 rear shafts, #2 piston rear and #3 front, 35wt front and 25wt rear, shocks on outer hole on rear wishbone, inner on front, middle on rear shock tower and inner on front shock tower, Associated blue springs front and silvers rear, ride height = chassis about 10mm (guessing from floor). Yellow Minipins all around, BC-Special wheels.

I have now raced with 45.5mm ackerman, which is pretty much bellcranks level like it is meant to be, and now I can get the wheels to tuck in to the slots/grooves on the wishbones nicely - so full lock acheived.

Chris

[BC Rog]

Chris, thank you for the vote of confidence!

Ok, I think your best option would be to try the king-pin ball studs on the front and use teh inner most hole on the top row of the tower. This needs approx a 60mm turnbuckle. The King-pin ball studs you need are the one's with the thicker hex at the base. The thin ones will need 2 M3 washers under them and are frankly a bit weedy!

I run 0deg toe in on the BC but sometimes run 0.25deg per side toe-out.

I have found that the medium anti roll bar on the rear helps but on a really bumpy track that's no good. However if the going is that rough the last 1% of steering response is no use as you'll be driving gently to miss the holes!!

If you can I'd run 30wt (all my oils are Associated by the way) as this might help without upsetting the rear to much. If it's smooth I'd go for 30wt and a rear bar rather than 30wt.

If desperation creeps in then try 30wt oil in the front.

Give it a try, no way I'd run the car with the original link on the front. Again just my opinion.

I can't say I've ever wanted the car much more aggressive than 35wt front, long link as described. 30wt rear with med bar and links set 1 out on mid row on tower outer most on the 2 hole hub (ok, I admit to running inner most on the hub occassionaly....).

Rog

Rog

[Gaz_Stanton]

Chris, You want to put the long Yokomo ball joints on the bottom of the front shocks. (AE ones fine on rear) I started with the AE ones on and the car was good but didn't quite have the turn-in I was after.
Once I put the longer ones on the car was transformed! The extra droop gives the car much more responsive turn-in and also handles the bumps & jumps and lands much better.

The best thing is that with all the extra turn-in the rear still hangs on! :D

My car (which is kit spec except for AE shocks) has been going great since. Only raced it twice this winter (damn uni work! >:( ) but at both Tiverton and Kidderminster I qualified on equal points to Mossy's new CAT. (2nd both times on FTD countback though. :( )

[Chrislong]

Thanks Guys,
King pin ball studs, are they so the outer link of the front turnbuckle is mounted via the kingkip rather than the hub, I bet this will get rid of the slight play I have.

Im ringing Dom tomorrow, will he know what i mean if i describe them or will he need part numbers? Will get myself a roll bar too, try it all out probably at Watford, borderline too late for York this weekend.

As for shock bottoms, I will try Yoke ones as theyre still in my tool box, but which spring retainers do you use? I guessed the yokomo spring retainers did not allow the spring to sit well - did I guess wrong :-[

The rear end handles superb, can't fault it, and stability of car is mega-forgiving, its just the bite I want on my steering.

Chris

[Gaz_Stanton]

You need to use the Yokomo spring cup on the Yokomo ball end as they are shaped to fit together.

Because they are slotted to fit over the shock shaft you can squeeze them in to fit in the smaller diameter AE spring.

As for anti-roll bar, I have used the B4 one at Kidderminster and it is fine. Where it is slightly longer than a Yok one it makes it more adjustable. (by moving the ball end along bar)

[Chrislong]

Thanks Gaz,
I fitted the Yokomo ball ends last night, and like you said I squeezed the cup a little and spring then sat nicely.

Do you run inner hole on wishbone? there seems to be loads and loads of droop now. Also, the shocks bottom at a sensible point now rather than still having 1/4" travel once chassis is on the deck.

I will order both B4 auntie roll bar and Yoke versions, and I will compare the two.

Hey, how noisy should the BC be? Mine whines and sounds aweful but no drag and its fast, I got a feeling the spur supplied has slightly poor teeth on, or have I built something wrongly?

Chris

[Gaz_Stanton]

Yeah, i use the inside hole on the front wishbone.

I use an adapted version of Neil Cragg's Euros set-up which is on the CML site. (same shock positions)

I've had no probs with noise from the car except when i blow diffs. But's that's another story!... ::)

[Chrislong]

Blow diffs? I haven't had any trouble yet, what happens to yours?

My car just sounds badly meshed, it runs true and I guess the motor plate isn't buckled as it was same on silver cast plate as with blue machined plate. Will try a new spur eventually but I keep forgetting to order one when I ring Dooom.

Chris

[Gaz_Stanton]

When I first had the car i was snapping diff screws left, right & centre. :o

Think it was a combination of tight diffs, a Reedy Kr 8x1, no slipper and a heavy throttle finger! ::)

Sorted now though. The shouldered diffs screws & backing the diffs off slightly did the trick.

[Chrislong]

Ive had no trouble with mine, running a V-revolution 10x2 which is quick and no diff screws given up on me. I did have 1 shouldered screw in the kit which went in the rear, got one in the front too now, my diffs are not that tight but not for that reason, although don't slip on the track.

Roll bar arrived this morning, will try on Sunday.

Chris

[Chrislong]

Figured out the screaming gearbox!

A string of coincidences led me to a B3 kimbrough 81 tooth spur gear in my pit box, still in packet. I was actually cleaning pit box after finding some shockoil had spilt over everything :-[

It fitted onto the blue one way nicely but with two screws, not four, and the car is as quite as it should be - if not quiter! I had to file a little of the gearcover to stop it catching since it is marginally wider, but no major problems.

Chris

[BC Rog]

The Robinson racing narrow spurs fit with no mods and no rubbing. Most people use these.

Rog

[Chrislong]

Had to make a few changes yesterday, worked best without roll bar, long shocks good on front but put them on outside hole on wishbone, and used 1 degree rear toe in.

It turned in sharp and lock was good, but I worn deep grooves on front wishbone on front and rear of both sides - atleast my steering is equal then!

Very quiet, and seemed to perform much better on 81 spur. After a full meeting the 10x2 didn't even need a skim but it got one.

Chris

[kriss]

Hi guys,
I am getting the standard BC kit next and have heard that it needs to be ballraced etc to make go well. Is there any other upgrades which are worth doing? I will be racing this car on a slippy floor at club level, but will be doing the outdoor regionals which are on grass. Can any of you guys advise a setup for either of these surfaces?
Thanks for any help given.

Chris