Camber Adjustment [again]

[Bob_Spidell]

My BJ8 has had what I feel is excessive pos. camber--2-3deg--since new (AFAIK), even with offset trunnion bushings 'maxed out.' Now that I can TIG weld with a bit of competence, I've considered adjustable shock plates but, while browsing the shelves at Harbor Freight the other day I noticed a box of alignment shims. These are roughly U-shaped and come in assorted thicknesses (yeah, I know, they've been around forever). Anyway, I got to thinking if I put shims under the outer ears on the front shocks that would tilt the shocks back and remove some or all of the pos. camber. My concern is, would this put undue stress on the ears--where the bolts go--on the shocks, possibly causing them to break and mayhem to ensue? Anybody done this?

https://www.harborfreight.com/catal...atured+Weight,f,Sale+Rank,f&q=alignment+shims

 

[Randy Forbes]

Bob, I think you already know the answer to this...

To get any meaningful gain__or positive camber reduction, in your case__you'd need a substantial amount of shims. I hope you don't take this idea any further, for safety's sake.

Now the adjustable plates method is something I can get behind! I had drawn up a plan to do something like that back when I restored my chassis (mid-80s) as they weren't commercially available yet. I just didn't have the equipment yet to make them up myself; nowadays, you can just buy them!

If I were doing them, I'd set up the front suspension "at ride height" without the spring fitted, and with the range of adjustment in the middle, shoot for 0* (zero degrees) camber. Clearly, you can bias their installation in or out, but if you could achieve settings between +1* to -2* you'd be all set.

Again, before you could buy them, I made eccentric bushes for my upper trunnions, and I think I'm getting -1-1/2 to -2* negative camber. Are you sure the eccentric bushes are oriented to pull the top of the king-pin inward (sorry, HAD to ask...)?

 

[Bob_Spidell]

Thanks, Randy. Yeah, I figured messing with the geometry of the shock wouldn't be a good idea, and I think canting the shock body would put undue stress on the bolt holes (the holes would no longer be orthogonal to the bolts). I do believe I have the trunnion bushings oriented correctly because I was able to take out some of the negative camber.

Adjustable shocks are the ideal way to go, but I've never figured out a way to make sure the caster angle is correct or, better yet, is there a better caster angle than stock? If you were really good at the suspension stuff, you could just grind off the old plates and just weld a new one in the exact spot to give the caster and camber you want (but, of course, you'd have to know what you want). No one is re-adjusting their camber before and after races, I suspect; it's 'set and forget.'

 

[red57]

Not sure anyone still does, but some sources used to offer eccentric bushes for the inner lower A arms too. When I started racing I wanted some negative and had to use a combination of the upper eccentric and the inner A arm eccentrics on one side (sides were not the same) - I think you can get a degree or more out of each, if I recall right.
No welding required....
Dave

 

[dougie]

Thanks, Randy. Yeah, I figured messing with the geometry of the shock wouldn't be a good idea, and I think canting the shock body would put undue stress on the bolt holes (the holes would no longer be orthogonal to the bolts). I do believe I have the trunnion bushings oriented correctly because I was able to take out some of the negative camber.

Adjustable shocks are the ideal way to go, but I've never figured out a way to make sure the caster angle is correct or, better yet, is there a better caster angle than stock? If you were really good at the suspension stuff, you could just grind off the old plates and just weld a new one in the exact spot to give the caster and camber you want (but, of course, you'd have to know what you want). No one is re-adjusting their camber before and after races, I suspect; it's 'set and forget.'

You're right Bob, after my pit crew gets the setting right I just run with it. Naturally, I give give each member a proper huge after the race......

 

[Bob_Spidell]

A 'huge' what?

 

[dougie]

A 'huge' what?

Ooops....... hug.

 

[Bob_Spidell]

The issue with camber adjustment on our cars has kinda bugged me for a while. We put adjustable plates on our BN2, but I don't think we got 0deg camber because the alignment crew didn't seem to know how to use it (not that I'm an expert). Now that I can TIG weld well enough to be confident, the ideal solution would be for me to decide what is the perfect setting for my style of driving (lots of highway cruising mixed in with any twisties I can find). Handling now is acceptable, and will probably be better when I get the DWR steering box installed, but I've always had excessive wear on the outside of the front tires (due, I assume, to the positive camber but also due to my driving somewhat). I'm guessing 0deg, or very slightly positive, camber and whatever caster angle lends itself to both stability on the highway but decent responsiveness in the twisties.

Of course, this means I have to become something of a suspension 'expert,' and I'd have to be able to try various settings to find the right one for me (which implies some kind of adjustability). Then, I would weld in stock shock plates in the correct/ideal and be done with it. Obviously, this would be difficult without an alignment system (the triangle-shaped camber tool that Randy posted a photo of would be a necessity; I already have the digital level).

Side note: One thing I don't understand--hence don't like--on the Kilmartin adjustable plates is the inboard edge of the plates have a long piece; I've always assume you either a) tack it down on the mount, or b) trim to fit then weld the edge. Anybody have an idea?

 

[red57]

Side note: One thing I don't understand--hence don't like--on the Kilmartin adjustable plates is the inboard edge of the plates have a long piece; I've always assume you either a) tack it down on the mount, or b) trim to fit then weld the edge. Anybody have an idea?​

If you are talking about these...

They get welded all the way around - they replace the stock shock mounts.

A lot easier way to go and cheaper is Tom's Import Toys adjustable plates - in that case you only cut open one end of the stock mount, knock out the welded nuts, slide the plate in and reweld where you cut it open.

The Kilmartin set does offer a much greater range of adjustment and is probably easier to change settings....

Dave

 

[steveg]

Tom's plates: couldn't one elongate the holes and take it to an alignment shop?

 

[red57]

The holes in the mounts are 9/16" and the bolts are 3/8" so the potential total movement is 3/16" or 3/32" either way from centered. I think this will be enough to allow the 1/2 to 1 degree I am after, but, if necessary I will elongate as required.

I think this is probably enough in most cases unless the frame is way off.

I just installed a set of Tom's plates last week and I like how simple they are to install.





The second part of your questions Steve is "take it to an alignment shop". This is not my recommendation. I have never found a shop that has anyone who knows anything about Healey's. And, since there are no "books" with a method of adjusting camber, their insurance might keep them from doing anything anyway - sort of like getting someone to turn your drums.....

DIY is very easy - set them somewhere near the middle of the range as a starting point, drop it onto the ground (roll back & forth) and check - if off, note how much and jack up the car, move the shocks, and repeat. Takes a while but no rocket science involved and a tool like Randy showed is all you need. This is the same method I've used for years to set eccentric bushings.

Dave

 

[dougie]

Dave -

We have a great shop here in Portland. http://tracksideracetires.com/ Garth has set up my race car for over 10 years. Every adjustment is saved and a copy is printed out for my files. We've made many "tweeks" over the years depending on the tracks and camber improvements I made to the car.

 

[Bob_Spidell]

Dave -

We have a great shop here in Portland. http://tracksideracetires.com/ Garth has set up my race car for over 10 years. Every adjustment is saved and a copy is printed out for my files. We've made many "tweeks" over the years depending on the tracks and camber improvements I made to the car.

Makes sense for a race car, but for a road-going only car a middlin' compromise should be sufficient. I like the idea of Tom's inserts, but the OEM shock plates are barely adequate to begin with and with the bending loads applied over years and hundreds of thousands of miles the plate metal can get fatigued and crack (I posted the same query to the email list gang and a couple people reported cracks in the shock plates and I've had one too). If I had a fab shop--bet Randy can do this--I'd start with thicker metal, weld the nuts around their entire periphery and bend the metal to form the plates then, knowing the ideal placement of the plate weld it in (I'd used grade 8 nuts but my research says it doesn't weld well). Camber shouldn't change much over time (unless you club a curb of course).

I think this could be done trial-and-error; since the shocks don't bear a (vertical) load when the car is still you could take your best SWAG--based on measurements made beforehand--tack weld the plates on then set the car down (gently) to check camber and caster. If you're off a little, just cut the tack welds and try again, until you get the desired result.

Anybody have a recommendation for best caster setting? 'Stock' seems OK for daily driving; too much and the car will track true but won't want to turn, too little and you've got a squirrelly Healey ... amiright?

 

[Bob_Spidell]

The holes in the mounts are 9/16" and the bolts are 3/8" so the potential total movement is 3/16" or 3/32" either way from centered. I think this will be enough to allow the 1/2 to 1 degree I am after, but, if necessary I will elongate as required.

I think this is probably enough in most cases unless the frame is way off.

I just installed a set of Tom's plates last week and I like how simple they are to install.
View attachment 58912
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The second part of your questions Steve is "take it to an alignment shop". This is not my recommendation. I have never found a shop that has anyone who knows anything about Healey's. And, since there are no "books" with a method of adjusting camber, their insurance might keep them from doing anything anyway - sort of like getting someone to turn your drums.....

DIY is very easy - set them somewhere near the middle of the range as a starting point, drop it onto the ground (roll back & forth) and check - if off, note how much and jack up the car, move the shocks, and repeat. Takes a while but no rocket science involved and a tool like Randy showed is all you need. This is the same method I've used for years to set eccentric bushings.

Dave

It's occurred to me that Tom's plates could have an additional advantage: they spread the load from the shocks to most of the plate, not just where the nuts are on a stock mount (they're sort of like a giant flat washer, spreading the load). I can't identify the physics involved, it just seems intuitive that they spread the bending and twisting loads over a greater area. Because of this, I think you could elongate and widen the holes in the shock plates to tweak both camber and caster.

Thoughts?

Edit: Of course, the Kilmartin adjustables also 'spread the load.'

Edit2: 'Nuff talk, I've decided to make a commitment (weasel words) to learn more about suspension and handling. I have a couple books around somewhere--'Chassis Engineering' comes to mind (but a textbook is NFG without real world experience)--and think I can drop a few hundred for gear (plates for the front, leveling platforms for the rear and ...) Randy, I looked for your link to the right-triangle shaped camber/caster tool but all I found was this:

https://www.amazon.com/Longacre-52-...ignment+tool&qid=1557981645&s=gateway&sr=8-27

(although maybe this is a good/better one?). If you still got the link handy please drop it here, or send a PM if you prefer. Either way, I already have the digital level so that helps.

TIA,
Bob

 

[Randy Forbes]

Oooh look! Pegasus now lists the frame only (if you already have the Smart Level)! https://www.pegasusautoracing.com/productdetails.asp?RecID=1203

For ease of handling, their "hands free" adapter also aids with castor readings (via compiled readings and calculation).

https://www.pegasusautoracing.com/productdetails.asp?RecID=1205

Those "Tom's Plates" are pretty much what I had envisioned 30+ years ago, but never followed through on it. Today, I would use the Kilmartin type; way more range than you're likely to ever want, but with the movement jack-screws would allow precise placing, versus influencing the shock with a BFH.

 

[Bob_Spidell]

Thanks!

 

[red57]

I'm not too sure you could do much with the castor even if you elongated the holes because if you only moved the shock rearwards for more castor, you could induce a bind in the trunnions that would increase wear/bind as they move through their arcs.
I'm no expert but I have spent lots of time staring at the front suspension - If you look closely at the front suspension from the side, you can see that the shock mounting plate is sloped downward towards the rear by about 2* which keeps the shock shaft parallel to the inner lower A arm bushings (book says they were supposed to have 2deg positive castor)... If you look at the whole works (shock mounts and lower inner a arm mounts) as a unit then you can see that if you only moved the shock without increasing the inclination of the mounts for the lower inner A arms, the shock and the A arms would scribe different arcs and it seems to me that could result in increased wear and/or other binding problems in the king pin trunnions. If we had ball joints instead of king pins this would not be a problem. This is all conjecture, I haven't tried it myself but I do think the car might benefit from more castor.

Or, is there enough clearance/slop in the trunnions and other joints that a minor change of shock position would not have an appreciable affect on wear/binding?

Has anybody tried increasing castor by moving the shock rearwards?

Dave

 

[Bob_Spidell]

To muddy the waters further: IIRC, caster is created by uneven distances between the front and rear lower A-arms; the bottom of the king pin is pushed forward by more distance between the rear A-arm and the front. So, if this is indeed the case--I recall reading about it years ago--the shock and A-arms are already in a bit of a bind, hence the use of (fairly) soft stock rubber bushings (may be part of the reason urethane or nylon bushings tend to squeak).

Anybody know for sure?

 

[Bob_Spidell]

What's the take on something like this:

https://www.ebay.com/itm/Profession...al-Camber-Gauge-Caster-Toe-tool-/281369075714

 

[John Turney]

What's the take on something like this:

https://www.ebay.com/itm/Profession...al-Camber-Gauge-Caster-Toe-tool-/281369075714

Seems like a lot of money for something you can't do much about, and wouldn't use more than once.