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MG Midget and Sprite Technical - TRE and gaiter

Hi,

I finally found the motivation to replace the steering gaiter, driver side, on my 1972 midget. After doing it for my first Midget, I had to do it on this one too... I was much quicker, but still not a nice time to spend on the car... Anyway, I am sure she will appreciate, and it also brings me some questions for you...

> One of my TRE feels really hard, difficult to move it by hand... So I want to replace it
=> I guess it is better to replace both at the same time ? Any good/ok-ish supplier for TRE ?

> My gaiter on the passenger side looks OK, but also pretty old...So I am thinking of changing it
=> Is it the same pain as the driver side ?

> I don't have the protective shiel n°24 on the picture. Is it to protect the gaiter from the metallic clip, or from other things ? Should I find a new one ?

Thanks :)
CH Hamon

Hum, you can't edit to add pictures, and of course, I forgot it :)


CH Hamon

It's to protect the gaiter from the clip. Rob
MG Moneypit

TREs are supposed to be stiff. If they move too easily, they are normally worn.

It all depends how stiff.
Dave O'Neill 2

Cedric

If your track rods ends are fine but the rubber boots are perished, you can buy replacement rubber boots: http://www.leacyclassics.com/parts/austin-healey/healey-sprite/steering/7h3762.html

https://www.morrisminorspares.com/steering-c92#page3:infscr1238269


(TREs and steering rack gaiters: http://www.leacyclassics.com/parts/austin-healey/healey-sprite/steering.html?p=2)

Note it is hard to find good quality rubber parts - I have had them perish quickly on TREs without much use (a few years in a dark garage)

Cheers
Mike
M Wood

Thanks for the feedbacks and ideas.
I think I will buy new TRE, so I will know how the feel new and then I will change only the rubber :)

Is it better to take greasable ones, or non-greasable ? My car has the Triumph rack, non-greasable out of the factory.

How hard is it to change the second gaiter, passenger side ? As "hard" as the driver one ? :/

Have a nice isolation/workshop day !
CH Hamon

When I needed new TRE's last year I was concerned about rubber on new parts, and I was given a contact by a member of this forum and he supplied me with a pair of NOS - a bit more expensive but I like to do jobs once. Really helpful guy is johndavis.vintage at internet.com

Colin
C Martin

Removing the TRE can alter the tracking. Back in the 90’s I had my car checked with on the car laser alignment, later realising it was hopelessly out. I bought a gunson Trakrite for just under £20; less than the cost of two professional checks. Looking to see if they were still available, they now cost typically £109. The average cost of a check is now reported to be £34. This inflation scares me to death.
L Langley

I've used one of those as well and as the toe in is the only setting you can easily change they're easy to use. I wouldn't buy one unless available cheaply. When you realise you're just checking the distance between the front and rear of the wheel rim at the centre height it's easy to make a tool to do the job, it just needs to be dropped in the centre to clear the chassis.
David Billington

I too have a Trakrite and think they do a decent job for the money. Dont know where you saw them for £100 but Amazon currently have them for £45 and no doubt you can beat that if you shop around.

Trev
T Mason

I'm thinking of a different tool, I thought it was Gunson that made it but basically a tool which was adjustable to allow you to compare the distance between the front and rear of the wheels ie toe in, it was dropped in the centre to clear the chassis and IIRC had solid end bars which slid in a channel. I can't find any pics at the moment.
David Billington

I was looking on the Gunson site Trev, £45 makes them an attractive proposition, better than paying a garage to make a cock up. David – make one I’m not that clever.
L Langley

I used Some angle iron, some welding (bolts would do), plus two longer bolts to make your own tracking jig. Easy job.

When I get a mo I’ll post a pic
Chris Madge

Chris – still interested in seeing your alignment gadget; been trying to imagine what it would look like. I recall one that compared the distance between the rear centre and front centre of the wheels, but it seemed to me that is all it would do. Assuming one wheel had zero toe and the other double toe out it would appear correct.
L Langley

I think that should read toe in.
L Langley

" Assuming one wheel had zero toe in and the other double toe out it would appear correct. "

If that were the case, under use they would automatically adjust to have equal (and correct) toe-in. Unless there were something else seriously wrong with the chassis or wheel alignment. Admittedly , your steering wheel might need recentering, but only fractionally.

My toe in measuring tool consists of two lengths of 3/8" dowling, two ex postman rubber bands, two pointers made from welding rod and some masking tape. It's very accurate. But it does get dismembered for "storage" between uses!
GuyW

Going back to Cedrics 2nd post I can't find anyone that stocks Item 24.
Rob
MG Moneypit

Hi,

Thanks for your feedbacks. Small updates:

I did contact John Davis, thanks for the contact Colin. For the records, the correct address is johndavis.vintage at btinternet.com (BT in front of internet).
Price are slightly higher, and it is the greasable one. So I finally bought "random" non-greasable ones on the Bay, waiting for them.

Concerning the gaiter on the passenger side, I will give it a go this afternoon. No comment from your side ? You don't want to afraid me ? :)

For item 24, if it is to protect the rubber from the clip, then I will not need it as I am using plastic ones now. But, if it is for this purpose, then why item 24 is not present on the other side...?

For alignment, I should give it a go one day (don't see or feel any issue for the moment, will keep track as I have new tyres :)). Thanks for the home made solutions ! I don't trust garages...
CH Hamon

Item 24 also serves to prevent the bellows from turning inside out on full lock. What might be described as sort of inverted prolapse, if you are not too squemish! The washer disk ensures that the bellows close up uniformly.

I have never found replacing the bellows especially difficult and cannot think why the steering box side should be any harder, or easier! If the TREs are ok you can do it by unscrewing the track rod from the outer TRE, leaving it attached to the steering arm, and if you mark the lock nut, track rod and TRE, and count the number of turns, then you can put it all back together without losing your toe-in setting, assuming it was correct to start with!
GuyW

Guy,
the problem is that many suppliers seem to use the same generic gaiters for both the Morris and Triumph racks (see photo) and they certainly don't go on to the Triumph racks easily. Then if you're unlucky they craze up in a few months anyway regardless of use.

They are difficult to fit because of physics, the gaiters are the wrong size and shape and take a lot of resource to be able to stretch them. Jolly-hockey-sticks types would probably have the rack out on the bench and relish the challenge each 6 months. And those with a grease fetish will love that the gaiters are so tight they redistribute the grease making everything slippery (control yourselves).

The proper Triumph style gaiters are obviously a better fit but sometimes the supplier doesn't make it obvious that they supply the generic version to both racks despite different parts numbers.



Nigel Atkins

Agree Nigel. But despite that, I have never found them difficult to do. Maybe I have been lucky and got the correct ones supplied.
GuyW

I have the one on the pictures :) But with plastic cable tie.
I have the one from Moss, they look better rubber quality (and molded) than the one from MGOC...

They might be hard to fit because of my two left hands then :D

I see your point regarding folding properly Guy... So maybe I will put a metallic washer ? Or look for something plastic in the kitchen I can cut :D

I did count the number of turns, and noted them on the TRE. Just need to double check the new ones will have same lengths...

It is not raining down there: let's the fun start !
CH Hamon

It might be that my Argentinian rack is bigger or different but I had a right pig of a job, twice. I had to wait for a hot day then prepare by pre-stretching the gaiter neck using increasing sizes of bottle necks over night and sources of heat, then using a hair dryer outside on the rack and gaiter on the car. Absolute pig of a job and that's using the mildest language I can think of, it was actually very f******, frustrating, b******* of a job with grease s*** going overwhere and no amount of f****** swearing helped. But luckily I kept my cool and was patient cos I releve in such jolly japes with the car and would have been delighted to share the experience with someone telling me how easy it was. :)
Nigel Atkins

Cedric,
you either you have an easier rack than me or you don't remember or listen, but will learn, I think the ones you want are these.



Nigel Atkins

So, it was not easy, like always for me :) Mainly due to the jubilee's screw's head not accessible to remove previous gaiter, and I didn't expect the gaiter to be so difficult to pass the ball joint... You really need a long and solid "ramp" to make it pass the ball joint.

Except from this, I am fine :)
I think you don't need 24 anymore thanks to the design of the new ones: it looks like they deform less/different thanks to a different design. Just my assumption based on Guy's opinion.
Picture 1 is new driver side, picture 2 is old passenger side






CH Hamon

As mentionned by Nigel, I have the "generic - one size doesn't feel any" ones, and not the "proper" Triumph designed ones. A good thread on TR6 forums is this one:
https://www.tr-register.co.uk/forums/index.php?/topic/58721-poor-quality-steering-rack-gaiters/

It is true that the generic one is smaller, but I don't think it is an issue: it will spread grease better everywhere ! So I decided to fit it anyway. The "real" issue is that I don't see how cable tie can work on this side: there is no 'throat"/recessed area for the cable tie to seat like on the driver side, so when you go on full lock, this is what happen...(You can also see on the picture how useless - and annoying - the red paint on the shocks can be... Just peels-off and goes everywhere...)

Do you know what are the correct size of jubilee clip to put ? Do you recommend any specific type of jubilee clip ?

Thanks ! Hope it can still be useful for someone one day in the archives...






CH Hamon

From the TR thread -
"Rimmers seem to the correct gaiters in stock, will report back when they arrive if they fit!"

If only that information was available in a thread or two or post or three in the Archives here.

And the poster duly reported back -
"Arrived today and fitted perfectly," - I wouldn't go that far for fitting to Midget but they do fit and a hell of a lot easier.

Be interesting to see if these generic ones last any longer than they used to.

Cedric,
pull your gaiter up and put a suitable cable-tie on it.
Nigel Atkins

In term of thickness, old and new are the same : around 2mm.
The "old" ones got old pretty nicely, even if I don't know how long they have been there... The got damaged only on the hose clip area, by "fatigue" I guess. I would guess - again - that the new ones have better design to fold/unfold better. Time will tell !

I will get some proper jubilee hose clip to fix them ;)
CH Hamon

Here is the first alignment jig I made. The long bolts can be screwed in and out, and I used the forward and rear edges of the wheel rims to set the screws to. You could use the side walls of the tyres. Then measure the gap between the ends of the screws to measure the difference and set the toe in.

The size of the angle iron on this one was too small - it had too much flex in it to be accurate so I made another with a much beefier section. But the design is the same. There is no reason why you could make the out of wood.






Chris Madge

Thanks for that Chris.
L Langley

Neat idea.

I've always used the string method, but I might try and fab one like yours.
Dave O'Neill 2

I made one years ago out of conduit which unscrewed in the middle to make it easier to put under the car and it had two flat pieces of bar for feet. The biggest problem with it was that you needed a really flat smooth surface to stand it on otherwise it flexed.

Trev
T Mason

I’m not the brightest one in the west Chris, I like the idea, but how is it used? If you put it so the bolts can be adjusted to touch the rear rim then bring it forward it should be wider than the distance between the front rims. How do you know the frame is in the same parallel position, if the distance is not 2x toe in figure which TRE would you alter? Having done a lot of checking with the Trakrite, (and had no uneven tyre wear), I know the adjustments are very small. The distance between the stub axle lever and the steering rack is fixed, the only variation can be made via the TRE thread to make the correct distance to give the required toe in/out. Each wheel is completely independent of each other; how does the gadget facilitate this? Just genuinely interested.
L Langley

When I've finished with the angle iron frame my shell is resting on I might convert it into a tracking gauge after reading above posts. Re. the wheels being straight ahead, I'm not convinced tyre places ensure that anyway and/or they don't necessarily "centre" the rack. Front wheels should be as near straight ahead as possible when tracking because they go out of paralell when turned, to comply with Akermann geometry.
Bill Bretherton

Ackerman steering is another thing that makes no sense to me, looking on Wiki the diagram demonstrating this is nonsense. In 1758 the idea was first thought of by Erasmus Darwin (grandfather of Charles Darwin). He was visiting a patient in Rugeley Staffordshire. His coachman turned his carriage round; the front axle turned through 90 degrees. Darwin was sitting in the front of the coach to one side, being a portly gentleman, the coach overturned, he sustained a broken leg. He came up with the ackerman idea in 1758; his house is open to the public, so I have seen the drawing he made, it was purely for stability. Rudolf Ackerman patented the idea for Georg Lankensperger since he was his agent in England this was in 1817. The ackerman idea was purely for stability, these people were dealing with horse drawn vehicles anything else would be irrelevant. What other type of steering would be better for a motor vehicle, any other benefits (if any) would just be a by-product. The undriven front wheels of any vehicle are free to turn as required. Where is the ackerman principle on the driven rear wheels, they turn on different turning circles.

L Langley

I think it's a compromise. Ideally there'd be a slight amount of rear wheel steer (which has been tried) but the diff speeds up the outer wheel and slows down the inner wheel to allow for the turning radii (and circumference). The front wheels are trying to maintain the turn so the different wheel angles assists with this. We need a mechanical engineer on this!
Bill Bretherton

The attached diagram is hugely over simplified (and poorly drawn) but gives a flavour of the concept.
Note the steering arms in the straight ahead position angle inwards from the hubs toward the centre line of the vehicle. This is crucial.
In the left turn shown the offside arm must pass through the centre of its arc but the nearside does not, so the offside wheel has less deflection relative to the direction of travel than its friend on the left and therefore describes a radius greater than the left wheel.
This is incidentally why it's critical to have the TREs adjusted correctly in the dead ahead position, to maintain the correct angular relationship between the two.
HTH.
ETA: The differential gear is not relevant to this action. It merely frees the outside wheel from the drive allowing it to overrun relative to the inside wheel.



Greybeard

Thanks for the input guys, I find these things interesting and as my old Physics teacher used to say: “Science is the pursuit of truth.” What amazes me is that things like differential gearing were used before cars were thought of.
L Langley

Of course, Grey's drawing needs an R2 revision for Spridgets as the steering rack and arms are ahead of the axle, not behind. Same principle and same effect but it looks very different...
Oddly I have one of Staniforth's books open in the kitchen at the Ackerman page as I was studying this the other day in an effort to reduce understeer (post-apex washout) on my racecar. Read it lots but still don't understand it ! (yet)
David Smith

To add to Greybeard and David's comments, Ackerman angle is designed into steering geometry to make the front wheels toe out on turns to reduce scrubbing(tyre wear)
If you can imagine a car with the steering on full lock, driving round in a circle the outside wheel will be travelling at say a 30foot diameter circle and the inside will be travelling at probably 22-24 ft- Therefor to keep the tyres on their correct arc to suit their travel the inside wheel needs to turn sharper than the outside wheel
The old simple measurement on old wheel alignment machines used to be 20deg outside and 22.5 inside but all cars don't require the same amount ,depending on how long they are and how fast they are
The rule of thumb is the faster you go the less ackerman you use
A F1 car would have 0
Usually there should be a line through the tie rod end , the king pin to the centre of the rear axle housing
With the steering mounted behind the centreline of the front axle this is easily designed in but when the steering is in front like our MGs then sometimes that line can't happen as the tierod end position has to be out wider than the line of the kingpin and the TRE would be out where the disc rotor gets in the way, so some cars have their ackerman reduced just to fit everything in
I've played with ackerman a lot on circle track cars that turn left all the time and it's a real art to get it right with slick racing tyres
Usually the result would be 0 toe in and 0 ackerman on the rhs and then play with the lhs ackerman until the rubber runs off the lh tyre equal to that on the right

On your washing out issue Dave
The big mistake, which I'm sure you're aware of is to run with toe in on the track, you have to have 0 or toe out, you could try a little more toe out and see if it makes a differance
If running toe in and a car with ackerman the transition period when turning from toe in to toe out and also when straightening up after a turn will always feel -soggy-you need constant toe out
Also what type of rear axle have you got, powerlock axles are prone to washout coming out of a turn unless you have bulk horsepower to override the feeling
Nuf from me
willy
William Revit

Willy your explanation is far better than my attempt, thanks.
I was aware that the assumed baseline is to project the angle lines to intersect the centre of the rear axle but as you have said other constraints impose compromises to this.
We used to have a rule of thumb that neutral or toe out would tend to promote understeer and toe in lean more to oversteer (if I've remembered it right), the trick being to find the sweet spot in between and these adjustments in effect move that theoretic intersection forward and backward where the setups you were using for left turn only effectively move it laterally. But it's not so simple because of all the other variables, some of which are controllable and others not. Tyre composition, condition and pressure. Road (or track) surface. Temperatures. Other geometry factors ie: castor, trail, spring rates and damping values. Vehicle weight distribution,which changes in response to fuel use. Even driver weight and position. Most people are not even aware that they automatically compensate for unequal weighting in right hand vs. left hand turns but your brain does it for you in the background. Rather like bikers and cyclists being mostly blissfully unaware that they countersteer to turn.
The biggest uncontrolled variable is preference. How the driver likes the feel of it. For example I'm okay with a little oversteer usually, but understeer makes me nervous.
It's really more Art than Science (for those of us outside of F1).

David you're right, the diagram I posted was a bit inadequate for Spridgets and inaccurate anyway but I didn't draw it - I just nicked it off the internet!
Greybeard

Cheers Greybeard
I'm hanging out to see an incar picky on telly of Lewis Hamilton when the season gets underway
Mercedes have been playing with cornering speeds and came up with a setting with truck loads of static toe out-The down side of their new found corner speed is that with the heaps of toe out they ended up with the car was undriveable down the straights- So they've come up with a sliding steering wheel so that when the car gets onto a longer straight Hamilton pulls back on the steering wheel and it sets the toe to straight ahead, then when he gets to the end of the straight pushes it back home for the magic cornering toe out
setting ----what could possibly go wrong-?

As you say each driver and what he's after is different, you like a car a little taily, I don't, I prefer just a tiddle pushy in the front but I've always been involved with big horsepower jiggers that can outpower a bit of push---most of the time-

Feeling a bit guilty, we've sort of nicked Cedric's post a bit
William Revit

Willy, with regard to the Mercedes idea I thought that the reason to alter it down the straights wasnt that it was undriveable but to gain a bit of speed on the straights due to the lack of tyre scrub which obviously helps tyre management too.

Trev
T Mason

Willy, yes I'm aware that a bit of toe-out is preferable; on my old car it was OK at slower speeds but was quite bad at high speeds, I remember first noticing it at Monza on the Parabolica back in about 2006 when Max T went past me on the inside 3 laps in a row (I was getting him back down the straights). The Lenham is not as bad but is still a bit iffy through Pouhon at Spa for instance, and Gerrards at Mallory Park.I tend to drive around issues like this but shared the car with a very experienced racer last year who suggested a long list of things to look at, starting with rear spring rates, rake angle, and Ackerman. I had to look it up! Now I've got a few months to think about it, so isolation and lockdown is no problem for me - except I can't go testing...
David Smith

Cheers Trev. -Dave

You're probably correct Trevor with the scrubbing I also heard he was having trouble keeping it in a straight line on the long bits as well, so maybe a combination

David
A mod I did to my Midget that made a significant difference to the car was- I had been running a 20mm front bar and the car felt really good but after a few laps it would get a bit too pushy in the front, went back to a 3/4 bar and that stopped that but made it a bit taily and lost drive out of corners a bit--Had a big measure up and decided to lift the front of the rear spring up into the body to level out the rear spring as much as I could to eliminate any roll steer-Took the front spring mounts out and extended them as far as I could, I think it was around 35-40mm, can't remember exactly but it went up in there a fair way and the car felt completely different ,it turned in as sharp as a tack but was really taily, Almost put it back to std and thought I'd give it a go with the big bar back on--perfect combo you could poke it in anywhere and it just stuck there--Don't know what rules you run under, but if you've got some spare spring mounts and it's allowed it might be worth a try--
William Revit

L Langley

My tracking gauge idea isnt perfect s :) It relies on having your front wheels straight ahead and the steering rack centered (IE same amount of thread showing on the ends of the TREs). Wheeling the car up and down the drive gets my wheels close enough to straight. I then set the tracking, drive the car, and repeat the process.

With the wheels straight ahead, I make the same adjustment to both TRE.

I have Rostyles, which have sufficient hollows in the wheel rim profile that allow you to wriggle the tool so that one end of the bolt tool goes into the recess and allows the other end to be moved so that you can get the tool out from the wheel to take the measurement between the bolts. Remember we are only talking a couple of mm at the most here.


As I say my gauge isn't perfect but I think it gets the tracking close enough for our (imperfect) cars.
Chris Madge

Chris – The proof of the pudding is in the eating- if it works fair enough. The last time I checked one was for my daughter’s bloke; a neighbour saw me and asked me to do his. He had uneven tyre wear but the Trakrite showed it wasn’t perfect but within tolerance. I put it down to poor tyre pressure maintenance. The adjustment is so minute I didn’t go to the trouble of trying to set it blind on. Just been wondering if the wear on the tyre caused a false reading.
L Langley

This thread was discussed between 31/03/2020 and 06/04/2020

MG Midget and Sprite Technical index

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