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Modifying Sierra steering rack
Dunc - 25/10/01 at 11:12 PM

I've done the sums and I'm going to have shorten the steering rack and extend the track rods, have any of you guys had to do this or know someone who has? Is it just a case of cutting right down the middle and welding back together or is there something more subtle?

Dunc - 6/11/01 at 11:43 AM

Managed to modify the steering rack quite easily. Dismantled the rack as per Haynes manual, removed the track rods and placed the rack in a lathe and used it to turn off 120mm from it's length at the opposite end from the rack. Drilled a 12mm dia x 20mm hole and tapped it with a M14 fine. Made 2 60mm extensions to go between the track rods and the track rod ends at either end, M14 standard thread. Cut the Aluminium rack housing in the middle and cut and welded in back together 120mm shorter. Sorted. Just in case any of you guys feel like doing the same. Total cost- 0p, Ron would be proud.


EA82T - 13/11/01 at 03:33 PM

Well done that man......

ChrisW - 14/11/01 at 05:31 PM

Just out of interest guys - is the Sierra rack the same way around as the mk2 Escort (ie it sits in front of the wishbones?)

Ppl have said that I can't use my mk4 escort rack because it'll turn the wrong way if put in the place shown in the book but I can't see why (space permitting) I can't have it behind the wishbones and swap the hubs left-right.

Hope that makes sense! Any comments?


Alan B - 14/11/01 at 09:20 PM


In theory you could. If a rack was used "rear-steer" (behind the wishbones) in its donor then it can be used "rear-steer" again" whatever the uprights. The only difference between a "front-steer" rack and "rear-steer" rack is whether the pinion is below, or above the rack. The only way a rack can be used opposite to its design position (front or rear) is by flipping it over, but then it becomes LHD or RHD depending what you started with. However, just because you could use a Mk.4 Escort rack, rear-steering a pair of swapped Cortina (or whatever) uprights, doesn't mean it's a good idea, there may be other considerations to think through.

Dunc - 15/11/01 at 11:24 AM


The sierra rack sits in front of the wishbones. I did think about swapping the left and right hubs around and making the steering rack behind the wishbones, the benefits I could see would be a shorter steering column with little or no modifications to the standard sierra column and the castor angle would be positive. Major problems with this however was the resulting steering geometry would've been anti-ackermann ie the inner wheel would turn less than the outer wheel giving severe tyre wear at any steering angle to name one, another problem is the thread of the hub would be reversed and could lead to the nut tending to loosen rather than tighten but could be solved by just swapping the uprights and not the hubs.

In the end I've opted to keep hubs and steering rack in roughly the same positions as original but I've rotated the upright 10 degrees to adjust the camber angle to positive 5 degrees.

You could use any rack in any car as long as it was like alan says in roughly the same position as original, ie, forward or rear of the axle centre, but careful consideration needs to be done on the actual position of the rack and effects of bump steer and turning has on the steering angle of each wheel.

ChrisW - 17/11/01 at 01:12 AM

Hmmm... this all sounds far more complicated than I thought! Best just get a 'front steer' rack!


Dunc - 18/11/01 at 11:54 PM


You should be able to use almost any rack but if you want it to be rear steer then you need to choose a rear steer set of uprights. If my memory if correct, the escort mk vi uprights are rear steer but you then might have the problem of what to do with what to do about the end of the drive shafts. Nothing a hacksaw and a pretty metal cap won't sort.


ChrisW - 19/11/01 at 12:44 PM

That would be an idea except... the Escort uprights went with the rest of the car to the big car park in the sky! Might be worth seeing if I can get some others though - Mk4's are common as muck!

Also, can someone please tell me if Sierra uprights are front or rear steer? Oh, and while I'm posting, what's a good price for a set of Cortina uprights?


Dunc - 20/11/01 at 01:08 AM

Sierra uprights are front steer.


Metal Hippy™ - 11/12/01 at 07:23 PM

On the subject of steering racks, we're using a Y reg Capri 1600.

Useful rack or a bin men job?

If not that, then what would you suggest.

We already have Cortina hubs and discs at the ready. Apart from that, no wishbones or anything as yet...



Dunc - 11/12/01 at 11:19 PM

I've heard of capri's, nope it's gone. Only joking, you could probably use any rack with any upright as long as the track rod ends fit, if they don't then you could try cortina track rod ends at the end of the track rods of the capri rack. The cars are of similar era but that does not mean they'll fit together. Check out the threads on both if you find capri track rod ends dont fit onto cortina uprights.

Also, have a think about where to locate the rack on the chassis with regard to the motions of the suspension and not just the most convenient place to bolt it. You want to reduce the effects of track and toe changes during bumps and body roll conditions.


Metal Hippy™ - 12/12/01 at 06:46 PM

Ok, thanks.


davimora - 8/1/03 at 08:59 AM

Hi Dunc,

can you post a sketch of how to modify the steering rack? I think can be useful for me (first! ) and also for others.

Dunc - 9/1/03 at 03:55 PM


I've done a quick sketch, ie poor quality in a rush type job, but hopefully you'll get the idea. I've left out my dimensions as it up to yourself to modify the suspension & steering geometry to suit your needs.

I cut 120mm (X value) from the rack and housing and added a spacer each side of 60mm to keep the same front track.


davimora - 10/1/03 at 07:40 AM

Hi Dunc,

thank you veeeeeeeeeeery much!
English is not my language, and often a sketch it's more useful than 10,000 words.


Barker - 15/1/03 at 01:13 PM

Dear Dunc

You mentioned b4 using maxi bottom ball joints on your CAD drawing it mentions "needs taper"

Do you need to modify ball joint to fit sierra hub or did you mean the steering rod ends

Also -I am going to shorten my top front wishbone by 30mm from Rons book - did you shorten by simlar amount??????



Dunc - 17/1/03 at 09:58 AM

The maxi ball joint sort of fits in the sierra hub, the threaded part fits in the hole and the taper engages in about 2mm. Not good in my opinion but some manufactures seemed to think it was ok as long as you tightened it properly.

I reamed the taper in the upright out a bit until the maxi ball joint fitted properly, would make me feel safer when driving.

As for the wishbones I think I went long top and bottom and also moved the mounting points to try and optimise the suspension geometry as the position of the upright upper and lower ball joints are pretty much fixed.