Impreza steering rack mod
Discussion
must be available from a main dealer as a spare part 
strangely 90% of current cars out there track/tie-rods just screw into the rack no thread lock tab-washers or anything 
Here's the situation after a bit of perseverance. Fetched away the last remnants of the corner of the plate to give myself an extra 2 mm, and this is with the rack in final position all tightened up.
The hose fitting will now go on but it sits flush with the chassis cross member. So I'll have to install the hose and then final-fit the rack, but that will leave no room for adjustment or removal without shifting the rack, not ideal.
Option 1: special fitting, which may have to be a custom part machined from scratch
Option 2: have the bump tube adapter modified to remove 2 threads, this might allow the hose to sit 3 mm higher and clear the chassis
Option 3: Slide a plain washer underneath the 120 mm plates at the top end, to rotate the rack and create clearance. I estimate a 1mm shim would give me 2mm extra clearance at the hose fitting... but the rack wouldn't be sitting completely flat on the mounts.
I'm going to see about (1) this tuesday AM and will probably have them incorporate (2) into it if its to be a custom.
Can't understand what's different, other than the rack is the FA082 variant not the FE060 in the other photos above.
The hose fitting will now go on but it sits flush with the chassis cross member. So I'll have to install the hose and then final-fit the rack, but that will leave no room for adjustment or removal without shifting the rack, not ideal.
Option 1: special fitting, which may have to be a custom part machined from scratch
Option 2: have the bump tube adapter modified to remove 2 threads, this might allow the hose to sit 3 mm higher and clear the chassis
Option 3: Slide a plain washer underneath the 120 mm plates at the top end, to rotate the rack and create clearance. I estimate a 1mm shim would give me 2mm extra clearance at the hose fitting... but the rack wouldn't be sitting completely flat on the mounts.
I'm going to see about (1) this tuesday AM and will probably have them incorporate (2) into it if its to be a custom.
Can't understand what's different, other than the rack is the FA082 variant not the FE060 in the other photos above.
Bit more playing this evening with some alternative fittings.
1) M14 banjo
Even worse clearance to the cross member, no joy.
2) JIC-6 male-female adapter
Extends the hose connection out/down by about 30 mm, but same fitting onto the bump stop adapter so doesn't actually solve the problem, and clashes with the diagonal cross member so the HP hose won't actually go on anyway.
Remaining options are
1) Fit the hose as is and see what happens. Worse case is it starts to leak.
2) Cut/grind a notch in the big cross member to get the extra clearance to the fitting
3) Find someone who can fabricate a custom fitting
4) Give up and re-install a TVR rack. Sell parts as a kit on ebay etc.
It must simply be that Trevor built these cars with a tape measure and a pint of mild, and the rib on my chassis is 2mm further back than other peoples. I can't fathom any other reason for the difference.
1) M14 banjo
Even worse clearance to the cross member, no joy.
2) JIC-6 male-female adapter
Extends the hose connection out/down by about 30 mm, but same fitting onto the bump stop adapter so doesn't actually solve the problem, and clashes with the diagonal cross member so the HP hose won't actually go on anyway.
Remaining options are
1) Fit the hose as is and see what happens. Worse case is it starts to leak.
2) Cut/grind a notch in the big cross member to get the extra clearance to the fitting
3) Find someone who can fabricate a custom fitting
4) Give up and re-install a TVR rack. Sell parts as a kit on ebay etc.
It must simply be that Trevor built these cars with a tape measure and a pint of mild, and the rib on my chassis is 2mm further back than other peoples. I can't fathom any other reason for the difference.
Classic Chim said:
Do you have any pictures of this so people without reading back can maybe come up with a solution.
I thought this was a fairly straight forward mod but maybe not.
2mm would be within tolerance back in the 90’s i’d imagine.
Pic above, and preliminary grumpiness on the previous page but here it is again:I thought this was a fairly straight forward mod but maybe not.
2mm would be within tolerance back in the 90’s i’d imagine.
Edited by Classic Chim on Wednesday 4th March 21:25
I'm not beaten. I'll tap up a couple of the specialists tomorrow for preofessional advice and have a full trial fit tomorrow evening with hose fitted before tightening the clamps down. If it really is too tight I'll start talking to specialist custom fittings fabbers and my local machine shop.
It doesn't help that the fitting protrudes as much as it does but even if it were 2 threads / 3mm shorter I don't think it would make a difference.
Your chassis pics on the FB page are very nice!
Edited by 2gins on Wednesday 4th March 21:39
Sorry I didn’t need to scroll up far to find it. Hmmm must be the rack.
The options you listed should sort it I’d think.
I’ve not done this so can’t comment. Am I right in thinking you add bushes to the rack mounting points to bring the Scooby rack out, if so if you reduce those by 1-2 mm would that not shift the rack back and clearing the cross tube enough to get pipe on.
I’d try connecting it up loose with pipes on and nipping it all up to check before going further but you might be ahead of me there. Goodluck as your having a right game by the sounds of it.
Thanks re chassis pics
The options you listed should sort it I’d think.
I’ve not done this so can’t comment. Am I right in thinking you add bushes to the rack mounting points to bring the Scooby rack out, if so if you reduce those by 1-2 mm would that not shift the rack back and clearing the cross tube enough to get pipe on.
I’d try connecting it up loose with pipes on and nipping it all up to check before going further but you might be ahead of me there. Goodluck as your having a right game by the sounds of it.
Thanks re chassis pics
Cheers Alun
Trouble is packing out the spacers doesn't actualy move the rack away from the chassis member, it just moves the rack in the other plane without affecting the clearance issue. I did think of 6 or 8mm standoff brackets instead on 5mm but it will affect Geo at some point before I get the rigfht clearance.
If I could move the rack 'up' away from the cross member (e.g. standoff brackets with 4 holes not 2), this then creates other clearance issues. To get the separation of the bolt holes to offset the rack from the original TVR mount location, the rack will foul the coolant swan neck pipe, but in any event long before that becomes an isue it will move the bottom UJ into very close proximity to the chassis upright (the one with the notch formed into it). We're talking a wafer thin clearance so even with the UJ fettled a bit to improve the clearance that degree of freedom becomes uncomfortably tight. Pic on the previous page. Any movement of the rack under extreme load, it may jam.
I don't think the problem is the rack. I think (hope/expect) we can trust Japanese mass production tolerances. The only differences in the various racks was the ratio (13, 15, 16.5:1). I think it's far more likely that TVR fixed the actual rack mount plates quite accurately and reproducibly from one chassis to the next (it is after all a quite important factor in the overall steering geometry!) but the bracing ribs were less critical and just 'banged on' any way and welded up. As you noted, a couple of mm in 1999 especially for what is probably an over-engineered brace rib was probably no bother.
Trouble is packing out the spacers doesn't actualy move the rack away from the chassis member, it just moves the rack in the other plane without affecting the clearance issue. I did think of 6 or 8mm standoff brackets instead on 5mm but it will affect Geo at some point before I get the rigfht clearance.
If I could move the rack 'up' away from the cross member (e.g. standoff brackets with 4 holes not 2), this then creates other clearance issues. To get the separation of the bolt holes to offset the rack from the original TVR mount location, the rack will foul the coolant swan neck pipe, but in any event long before that becomes an isue it will move the bottom UJ into very close proximity to the chassis upright (the one with the notch formed into it). We're talking a wafer thin clearance so even with the UJ fettled a bit to improve the clearance that degree of freedom becomes uncomfortably tight. Pic on the previous page. Any movement of the rack under extreme load, it may jam.
I don't think the problem is the rack. I think (hope/expect) we can trust Japanese mass production tolerances. The only differences in the various racks was the ratio (13, 15, 16.5:1). I think it's far more likely that TVR fixed the actual rack mount plates quite accurately and reproducibly from one chassis to the next (it is after all a quite important factor in the overall steering geometry!) but the bracing ribs were less critical and just 'banged on' any way and welded up. As you noted, a couple of mm in 1999 especially for what is probably an over-engineered brace rib was probably no bother.
I would try and reduce that fitting length, it may help depending on how big your hydraulic fittings are.
Pirtek etc tend to supply industrial type fittings which are much chunkier.
I used fittings and made my own hoses up from this supplier.
I may have a spare fitting if you want to try it out.
https://www.ebay.co.uk/itm/AN-6-AN6-AN-06-to-M14x1...
Pirtek etc tend to supply industrial type fittings which are much chunkier.
I used fittings and made my own hoses up from this supplier.
I may have a spare fitting if you want to try it out.
https://www.ebay.co.uk/itm/AN-6-AN6-AN-06-to-M14x1...
Edited by Belle427 on Thursday 5th March 07:54
Edited by Belle427 on Thursday 5th March 07:55
Well. That'll do.
HAving consulted with the professionals it turns out that the cross member is one hell of a beefy piece of metal and there's no problem borrowing a bit from it. Also cut the rib back a few mm more.
Hoses tomorrow evening hopefully. Then measure up for the linkage and on to the geometry / track rod length conundrum.
HAving consulted with the professionals it turns out that the cross member is one hell of a beefy piece of metal and there's no problem borrowing a bit from it. Also cut the rib back a few mm more.
Hoses tomorrow evening hopefully. Then measure up for the linkage and on to the geometry / track rod length conundrum.
2gins said:
Well. That'll do.
HAving consulted with the professionals it turns out that the cross member is one hell of a beefy piece of metal and there's no problem borrowing a bit from it. Also cut the rib back a few mm more.
Hoses tomorrow evening hopefully. Then measure up for the linkage and on to the geometry / track rod length conundrum.
Good Job HAving consulted with the professionals it turns out that the cross member is one hell of a beefy piece of metal and there's no problem borrowing a bit from it. Also cut the rib back a few mm more.
Hoses tomorrow evening hopefully. Then measure up for the linkage and on to the geometry / track rod length conundrum.
I couldn't find a shaft of the correct length so cut the old one and had it extended using CDS tube that Car Builder Solutions sell for this very purpose. They also sell a range of shafts and U/Js that may help you.
https://www.carbuilder.com/uk/cold-drawn-seamless-...
https://www.carbuilder.com/uk/cold-drawn-seamless-...
This is the one I used (44cm) it has generous spline length that can be trimmed.
Didn’t like the price but I had little option and it was less fussing around.
https://www.jksportscars.co.uk/product/steering-ex...
Didn’t like the price but I had little option and it was less fussing around.
https://www.jksportscars.co.uk/product/steering-ex...
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