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Shortening a steering rack
Mix - 1/12/05 at 05:11 PM

I apologise if this has been covered before but I don't remember it.
Can someone either explain in lay man's terms, or point me in the direction of the information required, on how to shorten a steering rack. I am particularly interested in shortening a MkII Escort rack but I would imagine the theory is much the same across the board.

Thanks Mick


Bob C - 1/12/05 at 05:42 PM

This wasn't hard, but I've got a lathe . . .
Dismantle (involves drilling out a pin - I only took the non- pinion end off). You'll have to take out the pinion & gibbins. The rack will all come out the pinion end now & you can shove the whole lot in your lathe with the non- pinion end sticking out to be worked on. Saw/part off the relevant amount (was 3.5" for me) Then make an exact copy of the end you've sliced off (you'll need to be OK with thread turning - 20tpi from memory but I might be wrong)
Now the housing must be shortened or you'll end up with severely limited lock - I shortened mine by 3" and this (luckily) looks just right for steering lock. Chop the relevant amount out of the middle. Now turn a sleeve with a good tight fit on the outside of the housing & weld it back together making sure the mountings are still in line. Note this weld keeps the oil in so take care.
Reassemble - drill a new hole in the rack & rivet a new pin in to lock it, paint it & fit. 3" off an escort rack housing left the mountings 7" apart which is strong enough for a light car I reckon. There's some pics in my archive & on my website (2004 section).
Not hard if you have a lathe & are prepared to use it!
Bob


Bob C - 1/12/05 at 05:48 PM

Here's the pic off my website
http://freespace.virgin.net/bob.carter/images/rackbits.jpg
Bob C


Sven - 1/12/05 at 08:38 PM

Not sure about the Escort rack, but I know how to shorten a VW Golf rack ...

Remove the pinion preload plate bolts and remove the gubbins, remove the pinion bolts and remove the pinion. The steering shaft now pulls out of the rack body.

The rack body is basically a steel tube in the center, which you can section and weld back together to make shorter.

The steering shaft is hardened steel and how I did mine was to put it in a mill and machine a slot in the shaft. The depth of the slot was half the diameter of the shaft and the width was twice what I wanted to shorten the rack. I then cut the shaft in the middle of the slot, turned one half 180 degrees and put it back together, mating up the halves. This method gives plenty of welding area. Grind the slot so the edges are chamfered to provide an area for a nice
welding bead because you'll need to grind off the high spots of the weld.

Another way is to chuck the shaft up in a lathe and cut off the length you need and rethread the end. This will probably require you (or a machine shop) having the right threading die.

-Steve


Bob C - 1/12/05 at 11:07 PM

No hardening worries with the escort rack - only the rack teeth are heat treated, the end you're working on is easily machinable!
cheers
Bob


NS Dev - 1/12/05 at 11:31 PM

none of the racks I have ever dealt with has been fully hardened.

They are usually made from a steel suited to induction hardening, and then the teeth are induction hardened, just as Bob said.

Cutting and welding a through hardening steel is a recipe for total disaster, it WILL break!!!


Rorty - 2/12/05 at 02:52 AM

I'll second that. Racks are normally made from nothing special and the teeth are usually hardened.
No matter what it was made of, I wouldn't weld a rack together. Even if you had to use ceramic inserts or aneal the end of the rack first, I would have machined it as detailed by Bob C above. That's the "standard" way of shortening racks.


Mix - 2/12/05 at 08:30 AM

Many thanks for the replies, definitly food for thought, Bob your website looks very interesting.

Mick


skint scotsman - 4/12/05 at 01:16 PM

info care of cita

it's not difficult to modify the steering rack to have the shaft central.
I've done it for my single seater and i believe it was an old escort rack.
Slide the rubber boots to the outside so you can see the ball joint witch connects the steering arm to the rack bar.
Unscrew the joint so the steering arm comes off.
Do this on both sides.
Remove the steering shaft so you can slide the rack out of the housing.
Now bear with me cause my English is not very good.
If you have the toothed bar in front of you,you will see that a large part has no teeth on it.This side of the rack is where the shortening will be done.
First you need to cut of the part where the joint was screwed on the rack,remember to do this on the side where no teeth are on the rack.
About 1" below the shoulder is where you cut off the threaded part.
Make this cut as straight as possible as this will help you line up the parts later on.
Now about half an inch from where the last teeth on the rack is (the same side you just cut off the threaded part) cut the blank remained part off.
You now should have a short rack with one threaded part for the joint and one straight side.
Grind a 30° bevell edge all around on the rack you cutted the side of and do the same on the threaded part you cutted of the end of the rack,this is done so the weld can be grinded flush later on without loosing to much strenght.
Dont worry about cutting the rack bar,it can be done with a hacksaw as this material is not hardened.
Take a steel "L" section and weld a few tabs on the sharp side so you can place the "L" section on the workbench and you have a "V".
If you now place the two round sections in the "V" they are lined up perfectly.
Clamp the in place and spot weld them in two places.Keep the clamps on untill both parts are cooled.
Grind off the eccesive weld and place the rack back in the "V" so you can spot weld two blobs 90° from the first two blobs.
Again keep the clamps on untill the material has cooled down.
Now you can fully weld the groove,let it cool and clean up the weld.
The housing of the rack needs to be shortened to.
One existing mounting tab can be used but be sure to leave enough material for a "U" clamp on the part you cut off.
It is possible that you need make some new plastic liners to keep the rack lined up in the housing but this will be no problem.
I dont know skint if this all make sence to you,as i said my English is terrible,but it's an easy job and should only take a couple of hours.
It's the cheapest way to convert an existing rack.
If you have any questions please do not hestitate to ask.

Cheers
Cita

did this myself recently wasn't overly difficult i used a mk2 fiesta rack (it was what i had) should have some b4 and after pics around some where.


hope that helps