What causes heavy steering at racing speeds - Page 3

roaldin · 06-19-07, 09:37 AM

Jim,

I have never compared but I was told by RF that it was a Cortina (possibly TD or maybe TF) rack... The Escort rack was supposedly too short.

Tim.

Jim c · 06-19-07, 09:43 AM

I have not compared either.
I have owned 2 escorts but that was a few years ago so you may be wright there Tim.
Cortina upright so it may be the same doner.

If you take the lock stops out that have been put in to reduce travel it has about 4 turns lock to lock.

Jim

Ross Nicol · 06-19-07, 09:55 AM

Yes definitely an early Cortina rack, I have a spare one just in case I need it. I also have an Escort quick rack and the linear travel for steering wheel rotation is the same as the Cortina.Funny isn't it there used to be a denial from RF that there were any donor parts in the car.
Ross

Malcolm · 06-19-07, 10:01 AM

Ross, I agree, reduce the 6.5 down to the 4.5 so they are equal. If not equal you can get the feeling that turning one way is really easier than turning the other. I once had this on my car. At Goodwood it was a breeze going through St Mary's but every right handed corner was heavy work. But boy was I quick through St Mary's. So much so I did consider staggering the car the other way but in the end I kept things equal.

By going back to 4.5 degrees you have a starting point that is fairly typical and you still have the option of loading it up by increasing back towards 6.5 as necessary. Also under braking did you find the car pulled up straight or was it trying to pull to one side?

I would be optimistic that sorting this unequalness out will give you quite some improvement from where you are now.

Lynn · 06-19-07, 12:13 PM

Good Stuff! I am really enjoying this thread

Trevor, I caught the idle speed question and couldn't wait to hear the explanation !

Chris (Flatchat), I second the motion that you share some of your experiences with setting up the DRB for the track! I am assuming that you were using 'Vette front uprights.

Thanks to all contributors,

Lynn

Howard Jones · 06-19-07, 02:31 PM

Frank, I was wondering if you have the specs/data for a standard GTD front upright laying around somewhere.

A drawing of the granada upright would be really useful.

I had the camber change data and if I can find it, I'll post it. If I remember correctly it wasn't too bad (camber change) and so I started my program at the rear of the car where it really is excessive and these cars really need some help.

If you can help with this, Thank you,

Howard.

Frank Catt · 06-19-07, 02:46 PM

Russ, funnily I have been out in a car with "my" suspension set up this afternoon on public roads, giving a demonstration ride to a Swiss friend.
At all speeds the steering is delightfully balanced and very light, the car runs straight and true with hands off the steering wheel completely at over 120mph, turns in with total accuracy and driver confidence, no bias to over or understeer at all -- just perfect. On the track it has exactly the same feel, its just so easy to drive. I must give all credit to Ray Christopher who started me on this fairly radical route, he has no fear of being considered conservative either. Frank

Frank Catt · 06-19-07, 02:48 PM

Howard, first area to consider for your car is changing the length of the lower rear A arm, the rest will follow.

Russ Noble · 06-19-07, 03:28 PM

Ahhh Frank...... That's no challenge!! Who wants a car that's easy to drive? Takes away all the excitement and surprises! It's much more satisfying to tame an unpredictable wild beast than it is to lead Daisy the affable house cow. 'course with Daisy you might live to tell the tale.........

Trevor, are you suggesting the problem could possibly be something basic like the inclination of the roll axis? Possibly another problem generated from the rear of the car?

I take the point about idle speed, if it's too low it makes the car more difficult to drive around the pits

That's why I went for the Ackerman instead, along with the overpaid pit crew

.

Cheers

Jac Mac · 06-19-07, 04:31 PM

Quote:

Originally Posted by Russ Noble

Ahhh Frank...... That's no challenge!! Who wants a car that's easy to drive? Takes away all the excitement and surprises! It's much more satisfying to tame an unpredictable wild beast than it is to lead Daisy the affable house cow. 'course with Daisy you might live to tell the tale.........

Trevor, are you suggesting the problem could possibly be something basic like the inclination of the roll axis? Possibly another problem generated from the rear of the car?

I take the point about idle speed, if it's too low it makes the car more difficult to drive around the pits

That's why I went for the Ackerman instead, along with the overpaid pit crew

.

Cheers

Noble, I hope your suspension geometry is not as warped as your sense of humour!! Archaic /Geriatric/Overpaid pit crew indeed- keep this up & Lim & I will jump ship to help Ross @ SFOS.

Can anyone confirm that the RF upright is modeled/borrowed from the Holden HQ/HZ series, if so I have dwgs somewhere from the old HQ race series when I was Tech Steward of the upright with angle's etc.

Jac Mac

Jim c · 06-19-07, 04:45 PM

Jac mac
It is a cortina TF -TE, they have 6.5kpi
part # 77BA3108AA are cast into knuckle.
They are not clear but I would say this # is OK.

Jim

Jac Mac · 06-19-07, 06:39 PM

Jim,
So that will be the Australian Cortina upright as fitted to the 6 cyl Falcon powered version we occasionaly see out here in NZ, NOT the english/german version which is considerably lighter.

Jac Mac

Ron Earp · 06-19-07, 06:41 PM

Quote:

Originally Posted by jac mac

Can anyone confirm that the RF upright is modeled/borrowed from the Holden HQ/HZ series, if so I have dwgs somewhere from the old HQ race series when I was Tech Steward of the upright with angle's etc.

Jac Mac

The front uprights and spindles that were on my RF kit were clearly stamped "Ford" with the oval, that is, they were a stock Ford part. I think that jive's with Jim in it being a Cortina part with the Ford part number.

Ron

Pete. · 06-19-07, 06:52 PM

Quote:

Originally Posted by roaldin

Yeah but there are some that sure sound stupid, like - Idle speed?

Tim.

Well here may be another dumb one. What is Akermann?

Ross Nicol · 06-19-07, 07:30 PM

I presume Trevor's Idle speed remark would be answered like this- If the idle speed is high when coming into a slow corner then the rear will be pushing you through the corner, much like a limited slip diff with a high breakaway or welded diff, makes it hard to turn the car. Pete - Ackerman is where the inside wheel is set to turn more sharply than the outer wheel in a turn. Been around since horse and cart days and said to work because the inside wheel travels along a shorter radius than the outside wheel.The reason for the Russ Noble/JacMac spat is that a car with Ackerman is easier to push around the pits and JacMac is nominated as Russ' crew chief.Now who was it that said "that's what motors are for" we are not allowed to start race engines till 9am at Phillip Island and similar at other circuits so a lot of pushing does have to happen.
I have 2 spare RF uprights Ford # 77BA3107AC 2.

My 2nd and 3rd piece of Data - upright steering pivot axis to tie rod attachment 125mm. I can take pictures if it helps.

King Pin Inclination- I measure 7.5 degrees but I could be out by a degree.

Ross

Ross Nicol · 06-19-07, 07:39 PM

Jac Mac
Upright weight 3.5 kg. I thought the only variation in Aussie Cortinas was when they dumped the heavy 6 cyl motor in it.Upset the handling apparently and never worked in the handling dept.
Ross

Ross Nicol · 06-19-07, 07:52 PM

Jim C - I got my spare uprights from a TC/TD Cortina I'm pretty sure the TE/TF being the later cars had different uprights and power steering racks.I have w/shop manuals for TC/TD.Sorry for 3 posts in a row I'm not totally on all cylinders yet today.
Ross