Re-welding spring perch- correct angle/castor (1 Viewer)

[peteinjp]

This is not cut and turn. I had a guy reposition the perches on my 70 series axle to fit my bj44 and he just whacked them in there carelessly. The inside shackle bushings are getting squished and the shackles are angled inwards and he felt the need to throw in some shims (that look to be the right width for a samurai) which makes wonder if the castor got screwed up in the process. Should have done it myself.....

Anyway I'm going to re do it and I need something to measure off of to get the perches at the correct angle. Can I use the face of the pinion and if so what should be the relative angle? Or should I measure off the top of the kingpin bearing surface and again what would be the correct angle? The current suspension is stock however I'm leaning towards a 2.5" lift in the future....

Best,

Pete

 

[Fast Eddy]

You should measure it from the top or bottom of the trunion bearing surface. Stock 40s, 55s and 60s are all supposed to have 1 degree of positive caster. If you're cutting off the perches it's a great time to decide you need 1/2" lift or lowering.

 

[Pin_Head]

On a stock 40 series, the differential mounting surface of the housing is vertical (0 degrees) and the spring mounting pads are horizontal (90 degrees).

 

[reddingcruiser]

Or, said another way, if the axle is fully assembled, there is no play in the pinion and you are on a level surface you could plumb the face of the companion flange and be at zero degrees.

 

[peteinjp]

Thanks guys. It's my daily so however I do it it needs to get done quickly. a solid weekend without the kids would do it and I may have to wait for that. Supposedly the perches were already moved once. Measuring the width between the top of the right and left shackles (fixed end) and the bottom of the shackles (spring end) there is an 8mm difference. The weird thing is that measuring the width of the springs in the middle at the perch is seems pretty close to where it should be. Anyway I have to get under there and really check it out to be sure. The bushings are definitely getting squished so the placement is weird. I thought maybe it was a bent spring but before the housing swap there was no problem.

The pinion is definitely pointed upwards with the shims. Not sure where the castor is at yet.......

Pete

 

[Pin_Head]

It is a 70 series axle, so it may be different. I was just stating what the specs were for 40 series axles. Castor is a bean that the toxin ricin comes from and castor oil is made from. Caster is a wheel alignment angle.

 

[peteinjp]

Haha- thanks for that.

So I'll ask up over in the 70 section about the perch angle relative to the dif. If I go with the measure at the knuckle should I stick with the 1deg?

Pete

 

[Pin_Head]

-1 is fine for manual steering; -2 or -3 is fine for power steering.

 

[Fast Eddy]

I wouldn't try to set it off the vehicle. Put the perches on loose, set the weight on it, set the caster, tack it in place, then take it apart and finish weld it.

 

[peteinjp]

Sounds like a project for early spring.... Say April? That would keep you busy on your trip!

Pete

 

[peteinjp]

I will go with power steering some day so maybe -2 is a good compromise.

Just kicking around the idea of doing a ubolt flip while I'm at it..... Pete

 

[Vossie]

I literally just finished doing this in my 45, put in a 60 series rear axel.

What I did was measure and find the half way point of the axel and then the position of the spring perches relative to that on my 40 axel. Then marked up those distances on the new 60 axel. Then rechecked... then triple checked.

For the angle relative to the diff, I put the perches on my springs (SUA) and then put the axel on them. Kept measuring distances between outside flange and perches whole time. When I was happy that every thing was dead straight and centre, I tacked the perches onto the axel, then took it out and had a friend of mine put a solid seam weld on it.

Looks like new now and I get 3" of total extra width

edit: my apologies for the double photo, my phone often does its own thing

 

[peteinjp]

Just measured everything and the perches are at least 5mm too close together. The shackles are 10mm closer together at the bottom than the top. As the rt side perch was ground down to a minimum there may not be muc left of it by the time I get it out. Ruff stuff perches maybe.

I'm thinking the best way is what eddy described but with the weight on the axle but the knuckles removed- as I'm planning an overhaul ther anyway and may need new birfs. With the knuckles removed I can get a good angle measure on the top bearing race surface.

So- if I'm going to go to all of this trouble and am thinking of switching springs out for 2.5" lift then it seems it would be best to get the springs in first and let them settle a bit and get the CASTER set up with those on. Right?

Pete

 

[Fast Eddy]

You will be able to get the best read on the angle with the knuckles removed. Good idea.

The 2.5" lift springs shouldn't affect the caster unless you're also going with longer shackles. If you're seriously planning power steering, I wouldn't compromise, go with 3 degrees while you're doing it.

And don't wait for me. It needs to be ready for me to drive around when I come out.

 

[peteinjp]

-1 is fine for manual steering; -2 or -3 is fine for power steering.

Shouldn't this be positive 2-3 deg?

Pete

 

[Fast Eddy]

I believe it is positive.

 

[Pin_Head]

Sorry it is positive.