Looking for TR6 spec 3 degrees caster trunnion.

[Martti Ojanen]

Hi guys!

 

I am now greatly puzzled about this trunnion confusion, there are trunnions with different caster angle.

First I found out that I have in my car on the right an original 3 degree trunnion and on the left some unmarked 1 degree trunnion. My wheel alignment report showed 2 degrees different caster angles.

Then I received replacement trunnion from Revington TR and it was also 1 degree trunnion.

I have made precise measurements to study the caster angle of the trunnions. Please see my blog about the measurement procedure at http://www.kolumbus.fi/~w429896/20122013-work/trunnion-confusion.html on my redesigned website.

I have asked part suppliers about this matter and they say that they sell reproduction parts that they believe are made to TR6 specs. Nobody can confirm that they are 3 degrees trunnions. Trunnions are sold being suitable for TR4A-TR6. Did caster angle change during TR4 production? I found a comment that late TR4's - TR6 have 3 degree castor.

Why these 1 degree trunnions are available for TR6?

Can I find an original LH trunnion anywhere? Or a reproduction trunnion with 3 degrees castor? My last option is to change also the right hand side trunnnion to 1 degree trunnion to get both sides similar.

So what you guys think about this matter?

Martti

[Steves_TR6]

You need someone who knows their trunnions........... Not me sadly

[John L]

Looking in the repair manual for the TR4a book number 510322 page 4.201 it states

 

'At commission number CT6344 wire wheels and CT 6390 disc wheels the castor angle was changed from 0 degrees to 3 degrees positive, This was achieved by the incorporation of modified upper wishbone arms, ball joints and vertical link trunnions'

 

Hope this might help

 

Regards John

[John L]

Looking further in the same book as above the trunnions for the TR4 at 3 degrees are different to those of the TR6,part numbers are also different so it would appear that the TR6 ones part number 142378 L/D and 142377 R/H should be 3 degress, should be easy to see the angle of the trunnion bore to the vertical.

John

[Peter Cobbold]

Martii

Left hand TR6 uprights were unavailable ( at least in UK) a few years back. Perhaps the situation has not been corrected with a supply of remanufactured 3degree uprights? and some suppliers are sending out 1degree items hoping no one will notice??

Try TRBitz.

Peter

[Grabea]

There was someone advertising brand newly manufactured uprights on E Bay a little while ago, I think it was one of the race prep outfits but can't remember who, I remember they weren't cheap but if that's the only way to put things right...

Regards

Graham

[stuart]

If you are talking about trunnions and not uprights themselves then Moss stock very good reproduction ones now in correct 3 degrees orientation, both left and right hand.

Stuart.

[AlanT]

UK law protects you with the "Distance Selling Regulations".

 

If you ordered these as being for use on a TR6, and they are NOT 3 degrees, then send them back and ask for your money back.

 

You are also entitled to claim the cost for sending them back. This is the law, but suppliers tend argue about the shipping cost.

 

Ordering from Moss-Europe.co.uk should get you the right ones.

 

Al.

[Martti Ojanen]

OK guys I have to admit that I was wrong and mislead by myself and my expectations.

I have now received a pair of new trunnions from Moss and I have compared them to the old ones and remeasured and checked my measurements an remeasured and remeasured and... I have to admit that measuring the caster angle of the trunnions is more difficult than I thought.

I CANNOT measure the caster accurately. My gauge is not precise enough for it. The only thing I can say about the trunnions is that THEY SEEM TO HAVE EQUAL CASTER ANGLE.

So the problem with my car is the frame and I have to try to correct it with shims.

Martti

[peejay4A]

Pardon my ignorance but I know how to correct for camber with shims but how do you correct for castor?

[Kiwifrog]

Pete

 

Remember Martti's first language is possibly not english, he may be getting castor, the leaning backward or forward of the vertical link in the direction of travel of the front wheels, confused with camber, the leaning inward or outward at 90° to the direction of travel.

 

Cheers

 

Alan

Edited January 20, 2013 by Kiwifrog

[Martti Ojanen]

If my car's frame is misaligned so that front suspension lower arm attachment holes are out of alignment, I can try to correct that by shims. Now that I have too little caster to start with, I will add shims to the rear lower front arm.

Martti

[peejay4A]

Alan, I don't think Martti has confused camber with castor.

 

Martti, if you add shims to the rear lower front suspension arm I could see how that would push the trunnion forward a small amount relative to the upper ball joint but it will also increase camber by a small amount also will it not?

Edited January 20, 2013 by peejay4A

[roulli]

Hi Martti,

 

If you want to measure the caster in the vice, you need to do it together with the respective vertical link.

I used a water-level and trigonometrics and my new vertical links and trunnions do have 3° caster.

First check, if the vice is leveled, by fixing the water-level alone into the vice. You want to use this to correct your measurement later, when you measure the caster with the vertical-link.

 

 

Also, the first think that gets bended if the wheel impacts strongly is the vertical link, so that might explain as well you differences in caster l&r

 

Cheers,

Patrick

[Colin White]

Martti,

I have done what you are proposing with my left hand rear suspension bracket. I needed about 10mm shims/packing to move the trunnion forward to result in similar castor angle to the right hand side therefore neutral steering (no pulling left). I bought a new lower suspension bracket from Revington with extended bolt lengths and made a 10mm thick steel packing plate drilled with the 2 holes rather than use shims. I also installed another 5 mm thick plate on the inside of the chassis bracket. The resulting camber angle is about 1 degree negative with 1 shim on the front left hand bracket, which is similar to the right hand side camber angle. The resulting castor angle (both sides) is about 2.7 degrees positive. The left hand wheel sits about 8 mm further from the chassis rail than the right hand wheel.

 

The most important thing to check is that once the packer is installed and everything bolted up that the vertical link and trunnion assembly rotates freely without any stiffness throughout its rotation - this should be checked without any tension form the spring and on both sides.

 

The alternative is to get the suspension bracket rewelded in the correct position.

 

I'm interested to hear how you get on.

 

Colin.

Edited January 20, 2013 by Colin White

[Kiwifrog]

Matty

 

Surley if the chassis is far enough out to affect the caster it has recieved a severe shock and would be trapozoid ? or at least the turret misaligned ? I would have thought measuring the datums on the chassis a better place to start before modifying the brackets ?

 

Alan