15 replies to this topic

[chuee]

Hello dear Accomplices.

 

Following removal of lower arm for the replacement of lower arm bushes with new, AND Upon examination of tie bars before replacement with new tie-bar bushes;

• I discovered my tie rods were bent, most likely since I aquired the vehicle, because tracking was fine, and I suspect tracking had been set with those bent ties.
• Those old tie bars appear to be standard design,  non-adjustable.

 

Upon replacing the ties with new, heavier duty adjustable type bars,  I  see a wild discrepancy between old and new tie bar length. After straightening the old ones;

• Old ones measure 14 1/4" = 361-362mm, from lower arm bolt centre to back of bushes flange.
• New adjustable are set at 15", more or less. 

I cant find here or elsewhere info on standard tie bar length.

 

Note on the fitting Adjustale Tie Bars:

• I adjusted the ties to obtain a  snug fit, without undue pull on lower arm, and without a gap at bushes before tightening the tie rod to subframe nut.
• THe car drives nicely at low speeds (up to 30 mph), having checked and re-adjusted tracking; higher speeds not checked.

 

 Such a substantial difference in tie bar lengths requires explanation, but I am stumped.

 

Perhaps I am fitting the adjuastables incorrectly, but doubt that is the explanantion. Surely pulling in a shorter tie rod woud alter standard mini caster ( I suspect that had been the case)?

• Before dismantling the lower arm to replace bushes, the old bushes together with lower arm, apeared to be pulled toward  the subframe-to-tierod fixing.

Your penetrating vision will be  appreciated. Cheers, John

Edited by chuee, 31 August 2024 - 12:38 PM.

[nicklouse]

Adjust them to the length of the originals.

Your caster will be way off. But you will now be able to adjust it to what is needed depending on your ride height.

[GraemeC]

A very quick Google:
The standard length is 14 5/16" from the front of the locating washer to the nearest edge of the bolt hole.

The adjustable wont have been set to anything in particular - you need to do that

[chuee]

Thanks guys, taken together, very  helpful.

[chuee]

Am I allowed a supplementary Question?

 

 

I am not sure if there is any benefit in 'upgraded' tie bars for a road mini, because I have always been led to believe that tie bars are designed beneficialy to be the sacrificial part of the suspension  in facing usual impacts from unven road surfaces (ruts etc), and kerbside knocks to wheels.

 

Of course, town roads in UK being in bad condition, such a perfectly designed weakness may be considered as dispensible in a trade off, BUT could  it really a good idea for a road car, AND; 

• At what risk to supension damage?
• How is a tie rod permanently bent, other than jacking up on one?

 

p.s. even my hydraulic suspension on a citroen xantia ended up with bent tie rods  from UK towns, back at the  end of last Century, and again in 2016.

Edited by chuee, 31 August 2024 - 08:15 PM.

[Midas Mk1]

Am I allowed a supplementary Question?


I am not sure if there is any benefit in 'upgraded' tie bars for a road mini, because I have always been led to believe that tie bars are designed beneficialy to be the sacrificial part of the suspension in facing usual impacts from unven road surfaces (ruts etc), and kerbside knocks to wheels.

Of course, town roads in UK being in bad condition, such a perfectly designed weakness may be considered as dispensible in a trade off, BUT could it really a good idea for a road car, AND;

• At what risk to supension damage?
• How is a tie rod permanently bent, other than jacking up on one?

p.s. even my pneumatic suspension on a citroen xantia ended up with bent tie rods from UK towns, back at the end of last Century, and again in 2016.

The heavy duty type bend, i’ve experience of mine not being straight after several years of fast road use.

Are they needed on a road car? yes, dialling castor is a very, very favourable thing.

[nicklouse]

Heavy duty not really needed. Some of the ones out there look really massive. This is normally down to poor materials. So they have to up the thread sizes.

 

adjustable is needed if your suspension is not totally standard. Or to correct the accuracy of a standard set up.

[68+86auto]

I wish someone would make a standard duty version or just a shorter non adjustable type. The steering/suspension was designed for cross-ply tyres. Radials generally require less positive camber and more positive caster. Leyland/Rover didn't bother to change anything when they went to radials.

[Spider]

In 99% of fitting, you needed worry too much about getting the rods to an exact xxx dimension, just as long as they are the same length as each other.

Same if adjustable lower arms are fitted.

If they are being fitted to make up for subframe errors though, if the errors are because there's differences from one side to the other, while in a static state, these errors can be equaled up however as the suspension moves each side will swing through different arcs and so throw desired the suspension settings to the 4 points of the compass so to speak.

I think there's a general perception (?) that the " subframes just aren't made that accurately ". While I can't say how well they were made (though, those I have checked have mostly been very accurate), the original drawings form them are to the 64th of an inch (+/- 0.4 mm). Having seen a few videos and jigs that they are made on, I can say, these sort of tolerances were definitely achievable and repeatable in production.

The only only real cure for a bent subframe or one that has had a bent is either to properly straighten and check it or replace it.

 

I wish someone would make a standard duty version or just a shorter non adjustable type. The steering/suspension was designed for cross-ply tyres. Radials generally require less positive camber and more positive caster. Leyland/Rover didn't bother to change anything when they went to radials.

 

Back in the early 80's, we had a local wheel alignment shop (Thornleigh Tyre and Wheel if memory serves) who would make adjustable Radius Rods and Lower Arms though, they needed your old arms to work from. They were good quality items, I think they were a bit on the expensive side, but at that time, there was little else available. There weren't as 'heavy' as much of the gear available now. I ran them on several cars I had at the time, including the Moke, they survived a 10000 km round trip across the Gunbarrel Highway OK. That firm eventually morphed in to what's known as Nolan Automotive today, who manufacture Nolathane Poly Bushes.

 

Leyland / Rover did make some late improvements but not in the way you are meaning, They came out with a stiffer hub and improved spec, CV, though the suspension angles still all remained the same !
 

[mbolt998]

If they are being fitted to make up for subframe errors though, if the errors are because there's differences from one side to the other, while in a static state, these errors can be equaled up however as the suspension moves each side will swing through different arcs and so throw desired the suspension settings to the 4 points of the compass so to speak.

I think there's a general perception (?) that the " subframes just aren't made that accurately ". While I can't say how well they were made (though, those I have checked have mostly been very accurate), the original drawings form them are to the 64th of an inch (+/- 0.4 mm). Having seen a few videos and jigs that they are made on, I can say, these sort of tolerances were definitely achievable and repeatable in production.

 

The little "ears" on the front of the subframe that the tie-rods bolt to are easily bent when you have an "off" into the ditch so worth checking those don't have any damage. I did this myself back in the day and got away with bending the ear back a few times before having to replace the whole subframe. I would have the confidence to reweld an "ear" now but not then!

[chuee]

Had some fun making a check regarding accuracy, I measured up alignment of my subframes in the car  with wheels  on last weekend, with only  rudimentary means using the wheels, and subframe centres.  Found them to be  well aligned, mesasuring accross diagonals, (and checking on width of  each end).

Sure, my measuring method may have been in all, up to 8 mm (lacking) in tolerance, given projecting and drawing on the ground,  yet the diagonals measured up spot on with an expanding steel tape.  Perhaps they were 8mm out, though!  

Anyway I was strangely happy, with increased confidence.

 

Tie rod length:

Although  their length  may not matter precisely,  incidentally I measured up both my  original tie rods, from edge of bolt hole to back of first bush (i.e the washer/flange) and found them to be both preceisely 14 1/4" , measured with a fine etched British  2' steel rule,  close up to the marks, without any error of eye prallax.  SOmeone may want ot confirm this.  Earlier  in this topic a reported google-search claim gave 14 5/16", which is a mile wider; no source such as Rover specs was quoted, nor whether  their measurement was off the car.

Edited by chuee, 03 September 2024 - 07:44 PM.

[Spider]

Measuring diagonals can produce very accurate results, nothing in the world wrong with that.

 

 no source such as Rover specs was quoted, nor whether  their measurement was off the car.

OK, now you made me go check, from a BMC Drawing, it is 14.44" to 14.47" from the centre of the bolt hole to the front of the disc that the rubber sits against.

[chuee]

OK, now you made me go check, from a BMC Drawing, it is 14.44" to 14.47" from the centre of the bolt hole to the front of the disc that the rubber sits against.

 

 

 

Ah So!  that earlier 'googled'  reference to a measurement 'from the edge of the bolthole'  also caused doubt, and I thought, surely  BMC/Rover engineer reference  drawings would measure from centre of hole?

 

Question answered! You sure have some decent literature and drawings.  

Cheers,

John

Edited by chuee, 04 September 2024 - 12:06 AM.

[GraemeC]

You’ll not be accurate enough with a steel rule to measure 14.44”-14.47”. Especially not when trying to estimate where the centre of a 1/4” hole is.
14 5/16” is easy to measure and is to an obvious hard reference (edge of hole).

14 5/16” is 14.3125”
The bolt hole is 1/4” diameter, so 1/8” radius = 0.125”

14.3125 + 0.125 = 14.4375” so a smidgen under Spider’s quoted figure (near enough for the difference not be discernible with a steel rule).
The discrepancy is probably due to the hole being a fraction more than 1/4” diameter to allow clearance for the bolt.


So yours are measuring at just 1/16” short. That will easily be taken up by the bend in them.

Edited by GraemeC, 04 September 2024 - 06:11 AM.

[Spider]

You’ll not be accurate enough with a steel rule to measure 14.44”-14.47”

 

Totally agree and hence my earlier suggestion of not getting tied up in knots over that, but just make the the same length.