Caster angle adjustment

[abowie]

Does anyone know how many turns of the fulcrum pin there are for a change one degree of caster angle?

[golfnut324]

Andrew,

I don't know how accurate this information is but it's a start and I believe Dave is a reliable source.

https://forums.jag-lovers.com/t/e-type- ... nt/92027/3

If it works out, can you let us know?

[abowie]

Brilliant.

I have checked and the stub axle carrier is exactly 10" high so with 14TPI, and assuming that arcsine is the right function, that calculation by Dave is spot on. I'm going to have to reread a bit of trig.

1 turn = 0.41 degrees.

I'll try it for real and see how it comes out.

[Gfhug]

Out of interest, as most of us would have to take our cars to a garage to get the camber, caster and alignment checked, do you take the various setting links along, or do they check without them?
Can't say I've ever seen any other car being checked with special setting links.

Thanks

Geoff

[mgcjag]

Hi Geoff.....thats a really interesting question...and i have given the whole idea of useing setting links quite a lot of thought and am still no clearer......the setting links are used according to the manual to set the mid laden point, but just take the rear camber for example.......the manual says depress the body and fit the links,.....have tried that, 2 large guys in the boot....still not depressed enough to fit the links.......I actually set the rear camber with the irs on the bench......which i think is what Jaguar did prior to installing it.......but if you then measure the camber with the car assembled just sitting normal you will get a different reading........i asked around a few of the major restorers and some race guys.....and they just set the car up as is on the ground.......i was looking at the rear camber of the Es on display at Bicester.....some had very noticable positive, some, negative, and some just central......I did set the front of mine at home useing a cheapish camber/castor gauge.....2 thin steel plates under the tyres as swivel plates.....its well worth doing as making the changes with shims would be impossible for a normal garage doing a line up check.....having said that did i notice a difference in the driving....no, maybee if i was a racer in the track i would

[abowie]

Out of interest, as most of us would have to take our cars to a garage to get the camber
Thanks

Geoff

I'm doing it myself because the last lot of "experts" I got to do a car turned out to be monkeys.

[chrisfell]

Out of interest, as most of us would have to take our cars to a garage to get the camber, caster and alignment checked, do you take the various setting links along, or do they check without them?
Can't say I've ever seen any other car being checked with special setting links.

Thanks

Geoff

Simple really. Mount a plumb line as shown and wait until it is steady. Then measure the difference between the plumb line and the centres of the top and bottom ball joints. Over the distance between them the required caster angle (2º +/- 0.5º) equates (IIRC) to 10-11mm. Adjust until it is in that range, and caster is set. Repeat on the other side.

If you are not a brick layer and cannot lay your hands on a plumb line, then tie a nut to a piece of string. it'll do the same job.

[Gfhug]

Steve, Andrew and Chris thanks for your replies. It seems that DIY could be the best way to go, and yes, Chris, I do have a plumbline , though can I remember where I've put it away?
Indeed, Chris, that looks like a very useful way to measure and set things up. Thanks.
And, Steve, I shall look for a couple of sheets of tin I can use as I am about to renew the front suspension rubbers and will need to either check and set all myself or find someone who really knows how to check an E Type.
I, too, set up my IRS on the bench to the correct camber, yet on the road there seems to be a positive angle to the wheels.
The handbook mid-laden position doesn't seem to relate to how the car actually sits on the road when loaded up, as shown by Steve's experiences, and I don't have a couple of heavy neighbours to borrow to load the car

Food for thought and it'll help me with my next job on the car.

Cheers
Geoff

[andrewh]

very interesting as I am just about to do this on my restoration. I have a castor/camber magnetic gauge , but need to the nifty gadget hooks over the tyre and touches the wheel rim top and bottom. Once this is in place you mount the gauge to give you a reading of camber. I have never quite worked out how to set up the castor with this instrument, but it does say it can be done. May just use the plumb line. I have been quoted £120 to set up the geometry by a local Classic Car company, but frankly, I am dubious about how much care will go into it and I don't want all my paintwork scratching by a hasty approach. Need to do the tracking as well. Don't want to divert this thread, but if anyone has a good tracking methodology please pm me or point me to another post.

[1954Etype]

When setting castor using the plumb line, don't forget the car must be level and tyre pressures correct.

[rfs1957]

I'm puzzled by the notion that it is possible to locate the "centres" of the top and bottom ball-joints to the precision required.

Or is it just that it's approximately 5mm per degree, we're aiming for 10mm which is 2°, and so anywhere between 7.5mm and 12.5mm is OK ?

Have I just answered my own question ?

[andrewh]

I also looked at the idea of locating the upper and lower centres and decided it was not possible to get it accurate enough. Back to drawing chalk lines on the garage floor!

[abowie]

The outcome.

Did the job today. We used a simple magnetic bubble gauge I bought on Ebay. Since you can't stick it accurately on the hub I made up a bracket out of angle with 2 pointers that fit in the wheel weight groove on opposite sides of the wheel. I zeroed this using a plumb bob.

I measured the distance between the front shock bolts. It was only about 15mm more than the "mid laden" measurement on the setting link suggested in the manual. So we just measured the car as it was on the ground and didn't bother making a link.

We measured camber first and set this correctly with shims. The book is spot on with one shim being 0.25 degrees.

We then measured castor. I put two plastic ice cream tub lids under each front tyre to make turning the wheel easy. We marked 25 degree angle lines on the floor with chalk. 25 degrees is pretty much full lock. Castor was easy to measure and was repeatable. The fulcrum pins were easy to turn with the castellated nuts loosened. One degree is indeed 2.5 turns. It was easy to set both sides to exactly 2 degrees positive castor.

We rechecked camber which was unchanged.

We then centred the rack and set toe in to 3mm.

Road test was good. Car drives well, centres positively and the steering is no heavier at the correct castor setting.

We rechecked all settings on return and they were unchanged.

Having done it once, I could do this again in an hour. I will not be taking my car to the monkeys, ever again.

[andrewh]

Brilliant. Good to hear its possible at home. I am going to set to on mine shortly. Where did you draw the 25 degree line from? centre of the wheel?

[Gfhug]

Andrew B, that's a brilliant write up. Any chance of a photo of the bracket you made up for the bubble gauge? Sadly, you're a bit far for me to bring my car to get you to do the work, so I will have to copy it as well as possible. And for a bear of little brain, photos help

Thanks
Geoff

[rfs1957]

I love it, Ice Cream Tub lids - only an Antipodean Cousin could add a detail like that.

My local colour will have to be putting a puddle of olive-oil under each contact patch.

This is what the local monkeys did to my spindles last year, is that where the term "monkey-wrench" came from ?



I had even brought them the correct A/F spanner to cope with the flats on the shaft .............

To be fair, I have no idea what the spindles and bushes were like as I have never had them apart.

Since I now have a complete set of spindles/bushes ready to fit, could someone confirm that it is indeed necessary to undo the (inaccessible) catellated nuts and split-pins in order to rotate the spindles ?

This was the bit the monkeys didn't grasp, any more than the monkey who owns the car.

[rfs1957]

PS If the "bubble-gauge" is the Gunson one, they made 10's of thousands of them with instructions that were wrong - I have this in writing from Gunson, after I queried the spiel that came with the tool.

https://www.google.fr/search?q=gunson+c ... kKs4oOFyWM:

"Nobody has ever asked that, you're the first" etc (cont. p92)

And what is the accepted Front Camber to aim for please ? I seem to remember a debate suggesting that modern tyres required negative camber, but can't find the link depsite searching for front+camber ?

[mgcjag]

Hi Rory....yes you have to slacken the castlated nuts to turn the fulcrum shaft.........as re the Gunson Guage....i have used it....the instructions arnt 100% clear.....eg when it mentions turn steering 20 deg it is refering to a road wheel, and not the steering wheel,....each wheel is measured seperatly through a 40deg movement......20deg either way from wheels faceing forward.....Andrew....you just need lines marked on the floor so you that you can tell that each road wheel has moved the 20deg each way.......photo of the bar i made up from unistrut and threaded rod so its adjustable......the 2 long studs touch on the wheel rim spaning over the spinner

[rfs1957]

I'd be really interested to see someone get their caster measured electronically (by monkeys) after they've done it with the Gunson Trackrite.

When I did the Mini with one, and then had it measured, I was way-off ; way-off the same amount, both sides, so it's consistent, but something like 50% more caster than what I thought I had put in.

This ties in with what I wrote here, where I first expressed my doubts.

viewtopic.php?f=3&t=6632&p=48491#p48491

But maybe not that thick since I ventured that "the instructions for Caster Angle are so awful and incorrect as to be risible ; the caster angle is specific to each king-pin pair (left or right) and the notion that you measure both at the same time as per the instructions - did anybody ever actually read what was printed ? - makes the tool worse than useless."

The manufacturer replied that "interestingly in the 5000 units sold in the last 2 years you are the first to report the error" and "I will do my best to provide you with some useable instruction. This will take some time as we will need to check the instructions for accuracy."

[mgcjag]

Hi Rory.....had mine checked with a Dunlop guage and it was very good.....since then i have proper plates on a 4 post lift so much easier to turn the wheels......although the instructions are incorrect the gunson is still just a bubble guage......all you are doing when setting the castor is taking 2 camber measurements....on the wheel turned in put the guage on and set to zero then turn wheel out and the castor angle is on tbe guage........when you brought the instruction z up with Gunson did they give you new instructions.......what are you going to use to set yours up, you can use the angle finder method........when you done your mini you wasnt really that far out...50% .....
on a S2 the Castor is 2deg+-1/2 pos so 50% out would be 3deg so only really 1/2deg out....... Its a bit debatably as to what the settings should be anyway what with different tyres....more important to have consistant measurements each side, then adjust to suit your driving,