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Discussion Starter #1
I have the complete trail gear hydraulic steering system installed in a landrover 300tdi defender.

Since the day I fitted this I am experiencing some issues as the steering pump must rotate left hand, I have an idler pulley and bracket installed to throw the belt so it turns the steering pump left handed. However due to the configuration of the idler pulley and a longer serpentine belt I am breaking bolts that hold the idler pulley bracket onto the engine, thus giving me reliability issues.

I have stripped and rebuild this system so many times on my motor however I can’t see what causes the bolts to break or what causes mechanical stress to the bolts.

All pulleys are perfect in line, no wobble in the belt; I really am at a loss over this.

I know lots of people have this design fitted and I have never heard of any problems.

I have ONE question
1) What is the best steering pump that will fit straight into where the landrover steering PUMP fits that would give me the correct flow and pressure for my hydraulic steering.

I have googled to I am blue in the face and CAN’T really find a correct answer to my problem

Many thanks
 

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Sorry, I follow what you are saying, but I haven't got the slightest clue on what a "trail gear hydraulic steering system installed in a landrover 300tdi defender" looks like.

I assume you are in the USA. AFAIK the 300Tdi was never exported to the USA, and didn't know there were many there at all. I doubt the steering system you speak of is used where 300Tdi engines are plentiful.

If it helps, in the UK, many upgrade the power steering pump when hydraulic winches are fitted. A popular upgrade/replacement is another ZF pump, but my memory of the correct designation is not clear, I think it is something like ZF74 (I stand to be corrected). I gather these are a simple bolt in upgrade.
 

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i am aware of this problem as the 300tdi /td5 steering pumps spin the opposite way to the PSC / Trailgear ones,

we need pictures of your bracket but from the sounds of it, needs more beef,

i had issues with my td5 crank pulley seperating due to the increased load on it from 2 alternators & the PSC steering pump
 

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Discussion Starter #4
i am aware of this problem as the 300tdi /td5 steering pumps spin the opposite way to the PSC / Trailgear ones,

we need pictures of your bracket but from the sounds of it, needs more beef,

i had issues with my td5 crank pulley seperating due to the increased load on it from 2 alternators & the PSC steering pump
hi
the bracket is 10mm thick no problems with it

the securing bolts that hold it in place keep breaking, I have helicoiled them

maybe I have the same issue with increased pressure with the pump and alternator

that's why I am looking to fit a different pump that spins right hand, something like a zf74 pump if it fits.
 

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Are your bolts that keep breaking loaded in shear on the threads? The helicoil comment sounds like the bolts are threaded into the brackets.

Instead drill the bracket for close clearance, put the bolt through, nylock nut on the other side and tighten appropriately. Then the bolts will make the bracket and mounting ears take the load in friction.
 

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We are all very much in the dark, and therefore there are too many imponderables to understand why the bolts are failing.

The loads come from the tension in the belt, which will almost certainly create moment plus shear loads on the bolted joint.

Without knowing the direction of the belt paths of the tight and slack sides of the belt, to appreciate the direction of the resultant force, and how far it is offset from the bolted joint, we have no idea of the magnitude of the moment and shear loads on the joint. Then the bolt loads, tension and shear, can't be estimated without knowing the disposition/locations of the bolts in the joint.

The information that the OP has given is insufficient to be able to provide any information that could fix the problem.

Some photographs showing the above information will help, because the reason may then be pretty obvious.
 

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Discussion Starter #7
We are all very much in the dark, and therefore there are too many imponderables to understand why the bolts are failing.

The loads come from the tension in the belt, which will almost certainly create moment plus shear loads on the bolted joint.

Without knowing the direction of the belt paths of the tight and slack sides of the belt, to appreciate the direction of the resultant force, and how far it is offset from the bolted joint, we have no idea of the magnitude of the moment and shear loads on the joint. Then the bolt loads, tension and shear, can't be estimated without knowing the disposition/locations of the bolts in the joint.

The information that the OP has given is insufficient to be able to provide any information that could fix the problem.

Some photographs showing the above information will help, because the reason may then be pretty obvious.
the bolt that breaks is circled in red, it secures the idler bracket to the engine block, and is a ally block hence the reason I drilled and inserted helicoils. there are only two bolts holding the bracket you can not see the other its behind the pulley wheel

 

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Gotcha. That pulley bracket isn't a good design. Can you fit bigger bolts or a backing plate which picks up more bolt holes?
 

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anyone got more info on which pump to use? when I search Google for ZF 74 I don't exactly get a good feeling about the results. Any idea what cars they come off from factory?
it sounds like this pump would be much preferred over a PSC system, I had never though that you wouldn't be able to get a PSC pump that rotated the correct direction.
 

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Why not look at some of the hydro winch set-ups from the Uk and use that and bypass the stock pump. Plenty of options for location, psi and gpm…Red winch comes to mind
 

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As Dougal said. The load on the idler pulley is twice the belt tension, and the tension in the belt is highest at that point.

It would help more if we knew the location of the other, hidden, bolt.

The obvious suggestion, from what can be seen, is to extend the idler pulley bracket to utilise the additional bolt circled in blue in this pic.

By spreading the bolts for the joint further apart like that you will greatly reduce the load in the individual bolts.

 

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anyone got more info on which pump to use? when I search Google for ZF 74 I don't exactly get a good feeling about the results. Any idea what cars they come off from factory?
it sounds like this pump would be much preferred over a PSC system, I had never though that you wouldn't be able to get a PSC pump that rotated the correct direction.
I'm with you on your feelings about the ZF74, because I could never find, with certainty, what vehicle they come from.

All the information on ZF74 appears to me to lead back to a company in the UK that sold winches for 4x4 vehicles. The sold Mile Marker hydraulic winches, which are very slow when the stock Land Rover power steering pumps are used. So they offered a so called Rapid kit, which included the ZF74 power steering pump.

For all I know he may have concocted the "74" designation for his own use and to prevent people bypassing him and finding used units elsewhere.

My best guess is they were used on some largish European vehicle, and I saw one post which said they were used on a Merc Benz W124 with the OM602 engine, though that info was not confirmed.
 

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I looked a little last night and agree with your conclusion about the OM602 data. I have an older MM single speed winch and want to install it, was planning on PSC stuff which isn't cheap, but if I cant make it work without some custom idler then an off the shelf alternative is very appealing. I have a stock disco pump that I was planning on doing mock up with for bracketry, maybe I will try to find some merc stuff in the scrapyard and mess around with it?
I did find some Caterpillar references in the Google-researching I did, so maybe its an industrial thing?
 

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anyone got more info on which pump to use? when I search Google for ZF 74 I don't exactly get a good feeling about the results. Any idea what cars they come off from factory?
it sounds like this pump would be much preferred over a PSC system, I had never though that you wouldn't be able to get a PSC pump that rotated the correct direction.
There is a PSC pump that rotates backward. Its a TC pump and it mounts into the existing holes but you have to trim the waterpump. Call PSC and ask for what they sold David Buchberger.

I ran it for years. Its a good system for a TC style pump.

OP: Dump all that. It's poorly designed. Puts too much pressure on that tiny pulley. Run the pump backward. Cheers
 

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Discussion Starter #15
update

well I removed all the brackets and trail gear steering pump from my hydraulic system on my landy, I fitted a Landrover TD5 pump and reverted back to the original design of the drive belt, have COMPLETED three completions and no problems with the steering :D:D:D:D:D:D

its good that I know my steering will not be an issue now when off roading

cheers:):):)
 

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Sam77, I'm looking at fitting the Trail Gear hydro steer kit to my defender 300tdi do you have any pictures of it fitted to the axle and how it fits to the hubs?
Many thanks
Willy.
 
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