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Author: Subject: Steering rack help.....
CosKev3

posted on 23/5/14 at 08:02 PM Reply With Quote
Steering rack help.....

Looking at the angle of the steering arms on my Mac1 the steering rack is too high,so the arms are not level which is causing my bump steer?

If I stand on the front of the chassis and press it down I can see by eye the front wheels go to 'toe out' by quite alot as the chassis goes down.



The rack came with my kit,can anyone confirm it is the correct type for the Mac1 ZR chassis please?

As looking at other pics of Sierra racks they look like they would sit a fair bit lower than mine once mounted,due to the mounting points being not as high.







Cheers

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jacko

posted on 23/5/14 at 08:07 PM Reply With Quote
The rack you have is a all steel sierra rack it is like the one i have on my indy
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Dave Bailey

posted on 23/5/14 at 08:08 PM Reply With Quote
Well.... I'm afraid to say I can't see it! The rack pivot seems to be on the wish bone pivot line.. It's not horizontal but there must be cars out there much worse than this.... Mine probably!

Dave B

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CosKev3

posted on 23/5/14 at 08:37 PM Reply With Quote
quote:
Originally posted by Dave Bailey
Well.... I'm afraid to say I can't see it! The rack pivot seems to be on the wish bone pivot line.. It's not horizontal but there must be cars out there much worse than this.... Mine probably!

Dave B


Pivot is not quite in line,prob about 50mm out.
The toe out when the chassis is pressed down is quite alot,as I say its easy to see by eye,no fancy gauges or nowt required!

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britishtrident

posted on 23/5/14 at 08:42 PM Reply With Quote
The angular positioning of offset mushrooms has a major effect on bump steer.





[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]

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CosKev3

posted on 23/5/14 at 08:49 PM Reply With Quote
quote:
Originally posted by britishtrident
The angular positioning of offset mushrooms has a major effect on bump steer.


Ok cheers.

Mine are fitted with the hole as far forward as possible,as per the Mac1 build plan.

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jacko

posted on 23/5/14 at 08:57 PM Reply With Quote
On my car where the rack bolts to the brackets the holes in the brackets are slotted if you moved the rack down the brackets would that help ?
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CosKev3

posted on 24/5/14 at 04:14 AM Reply With Quote
quote:
Originally posted by jacko
On my car where the rack bolts to the brackets the holes in the brackets are slotted if you move the rack down the brackets would that help ?


ok cheers.
I could do that, but by doing that the track rod arms would then be at quite a angle forward to the hubs, as in the racks position now they are angled slightly forwards.
Pretty sure the arms want to be as straight as possible to hubs?

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britishtrident

posted on 24/5/14 at 06:03 AM Reply With Quote
The track rods should actually point forwards that is the rack is mounted behind the imaginary line joining the track rod end centres.

The best way to deal with the problem may be to convert the track rod ends to rod ends bearings (Rose joints) with the joint mounted above the steering arm.

[Edited on 24/5/14 by britishtrident]

[Edited on 24/5/14 by britishtrident]





[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]

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Nick_TitanMsport

posted on 24/5/14 at 05:22 PM Reply With Quote
Hi guys. Sorry to hijack this especially with my first post. I have just bought an indy r and know Danny from MK through work. I work for Titan Motorsport where one of our capabilities is bespoke racks. As supplied direct to Caterham and a similar rack used for the S1 lotus. It would be great if I could understand if all you guys are mounting the same racks in the same place etc. if I can show the numbers Titan may invest in designing a rack we can all use. I will start a new thread if you guys can get involved and spread the word it would be great.

Ps we had this problem with the Ultima GTR rack we did (to customer spec) can you mount the rack lower?

Cheers.

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CosKev3

posted on 24/5/14 at 06:28 PM Reply With Quote
quote:
Originally posted by britishtrident
The track rods should actually point forwards that is the rack is mounted behind the imaginary line joining the track rod end centres.

The best way to deal with the problem may be to convert the track rod ends to rod ends bearings (Rose joints) with the joint mounted above the steering arm.

[Edited on 24/5/14 by britishtrident]

[Edited on 24/5/14 by britishtrident]


Ah right ok cheers so them being angled forwards is ok.
Does converting to rod ends involve machining the hubs?

No probs posting in this thread Nick, sounds interesting.
Suppose a lot will depend on price compared to a shortened Sierra one.

To lower the rack I will need to cut the rack mounting points, which is what I think I will do tbh as it looks easy enough to do.

Quite fancy a quick rack after reading people's experience's of them compared to standard ratio, but looking at quick rack kits available they state only fits the alloy Sierra rack, so will need to get a different rack anyway!

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