Camber on rear wheels

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Ride_on
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Re: Camber on rear wheels

Post by Ride_on » 02 Jul 2010 03:24 pm

Throwing a few calculation together I estimate that the axle could be straightened using a 2T bottle jack (20T is easily purchased). However what would be really useful if some of you mad young uns could measure the acceleration peak with an iPhone or similar new flangled wizardry.

I think the biggest force will be in 1st gear breaking the friction for a wheel spin on a good surface with grippy tyres. Obviously clamp or tape the accelerometer horizontally to a rigid part of the car.

The engine can impart a large force from its rotational momentum (rev er up and bang the clutch out), and this is partially resisted to the body by the springs and RHS radius arm. The resulting toe-in force seems to be quite small (around 2000-3000N per wheel assuming smooth 0-30mph in 3s), but it would be really useful to know the peak acceleration during abuse and work out a worst case, assuming the spring-axle joint is a hinge. A 2T bottle jack can exert around 20,000N.
1980 345 DL_______1987 360 GLE (project car restored to GLT spec and B230FT'd)
1984 360 GLT______1987 360 GLT
1983 360 GLS______1989 360 GLE
1985 340 GL_______1986 340 1.4
1985 360 GLS______1995 940 SE 2.3 Turbo Estate (daily)
1987 340 GL 1.7

mat_91
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Re: Camber on rear wheels

Post by mat_91 » 02 Jul 2010 03:33 pm

dam ride on thats technical id just weld on some thick box section to the bottom of the axle or down the sides maybe even triangulate it but with out a diff there
its pointless Q why are you going so deep into it as i would just make it as strong as poss bent to the right degrees
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Chris_C
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Re: Camber on rear wheels

Post by Chris_C » 02 Jul 2010 07:19 pm

But whats the right measurement?

Book value for *all* 300's according to the Supertracker computer (they have about 9 different models on) 2 degrees on the rear. I havn't checked the green books. That much rear camber (a hell of a lot for a stock car) is interesting as we have 0 rear toe. Toe gives stability, so thats why they will drift a bit and camber gives grip.

Cutting and welding the axle to a degree, let alone fractions of degrees just isn't realisitic, but I do have a plan ;)
'89(G) 340 GLE B172k
'03 S60 D5 SE, '91 (J) MX5, 1954 Cyclemaster
Ex:
'89(F) 340 GL F7R (ex B172k) - Fake -> SBKV 300 Runner Up 08, 12; '91(H) 340 GL B14.4E - Kar; '88(F) 360 GLT B200E - Jet -> BKV 300 Runner Up 09; '89(G) 360 GLT B200E - Beast

mat_91
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Re: Camber on rear wheels

Post by mat_91 » 02 Jul 2010 07:42 pm

i mean just using the jack then welding the strengthing stuff in
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Ride_on
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Re: Camber on rear wheels

Post by Ride_on » 03 Jul 2010 03:08 am

Well I wanted to know how much force would be needed to straighten it without cutting, as cutting will change the width slightly, although probably not significantly, but also your welding has to be very good quality.

Also would be nice to know how much force it needs to resist, and not overdo the strengthening adding unsprung weight. I also want a neat solution that looks original.

Not so sure about toe-in providing stability, I don't see how. Bent axle 300 series with toe-in are unstable IMO, when you go round a corner hard and hit some variation on the road it can suddenly break away, parallel rear wheels will be give a more controlled and gradual break away. In a straight line, again there is instability, hit a less grippy surface or sudden camber on the road, a dip or whatever and again the cars rear goes in the direction of the grippy wheel. My first 340 got so bad I had to change the axle for a less abused one. It still wasn't as good as a new one though, when new they are very precise.

Haynes states:
Rear toe-in : 0 +/-3mm (or +/- 0.15 deg)
Camber: -2 +/-0.5 deg

For RWD they tend to aim for the toe-in at the front to allow for mechanical movement (bushes compressing/looseness in the linkages/bending etc) under breaking.

My project 360 GLE
Rear camber: -1.5 deg both sides
Toe-in rough measurement against the sill: 1.2deg
1980 345 DL_______1987 360 GLE (project car restored to GLT spec and B230FT'd)
1984 360 GLT______1987 360 GLT
1983 360 GLS______1989 360 GLE
1985 340 GL_______1986 340 1.4
1985 360 GLS______1995 940 SE 2.3 Turbo Estate (daily)
1987 340 GL 1.7

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Chris_C
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Re: Camber on rear wheels

Post by Chris_C » 03 Jul 2010 05:28 am

I was working on the fact that the point of rotation of the car with 0 toe on the rear wheels has to be directly in line with the rear axle for there to be no slip angle. As it stands, the point of rotation is no where near there, it's either around the B pillars normally for shifted even further forward when the back end breaks loose. Toe in on the rear provides the outside tyre (i.e. the one loaded on a corner) to have no slip angle and a "perfect" line relative to the point of rotation.

I like the way the 300 works as standard, it gives control and grip, it's just not hugely standard for a production car.
'89(G) 340 GLE B172k
'03 S60 D5 SE, '91 (J) MX5, 1954 Cyclemaster
Ex:
'89(F) 340 GL F7R (ex B172k) - Fake -> SBKV 300 Runner Up 08, 12; '91(H) 340 GL B14.4E - Kar; '88(F) 360 GLT B200E - Jet -> BKV 300 Runner Up 09; '89(G) 360 GLT B200E - Beast

Ride_on
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Re: Camber on rear wheels

Post by Ride_on » 03 Jul 2010 02:36 pm

Chris_C wrote:I was working on the fact that the point of rotation of the car with 0 toe on the rear wheels has to be directly in line with the rear axle for there to be no slip angle. As it stands, the point of rotation is no where near there, it's either around the B pillars normally for shifted even further forward when the back end breaks loose. Toe in on the rear provides the outside tyre (i.e. the one loaded on a corner) to have no slip angle and a "perfect" line relative to the point of rotation.
Not quite sure what you are saying, but I don't think you are correct. If you have 4 wheel steering, you might want all to trace the circle you are trying to follow to give the best low speed manoeuvring (biggest change of direction in shortest space). If you are rallying or doing high speed you want the rear to point the same direction as the fronts (just less so so you can change direction as well), to get the back round the bend rather than just follow the front(using all the tyres more). Its not about following the circle you are tracing.

I don't think there is any slippage (the diff allows for speed difference), just the rears don't provide any steering. You can trace any radius with the rear axle without slippage, aside from the change of direction of the wheel (the resistance felt when turn the steering wheel as a standstill).

Yes the loaded wheel will be better toed-in (to the body, but not the other wheel) to get the back around the corner (such as the rallying 4wh steer), but this benefit is more than offset by variations in the road, change of control inputs etc causing the other wheel to fight the direction when it sees some grip.
1980 345 DL_______1987 360 GLE (project car restored to GLT spec and B230FT'd)
1984 360 GLT______1987 360 GLT
1983 360 GLS______1989 360 GLE
1985 340 GL_______1986 340 1.4
1985 360 GLS______1995 940 SE 2.3 Turbo Estate (daily)
1987 340 GL 1.7

antoni
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Re: Camber on rear wheels

Post by antoni » 14 Jul 2010 09:40 pm

you can camber the rear more, m10 washers on the bottom bolts in between the drum and the hub

Made my drifter much easier to get out and alot easier to control when sideways

Ride_on
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Re: Camber on rear wheels

Post by Ride_on » 15 Jul 2010 01:52 am

antoni wrote:you can camber the rear more, m10 washers on the bottom bolts in between the drum and the hub

Made my drifter much easier to get out and alot easier to control when sideways
Yes others have mentioned this, and noone so far reported any failures AFAIK. However I would be concerned about bolt failures or the alloy hub cracking.

Fine if the car is driven only on the track, but you really don't want failure at 70mpg on the motorway.
1980 345 DL_______1987 360 GLE (project car restored to GLT spec and B230FT'd)
1984 360 GLT______1987 360 GLT
1983 360 GLS______1989 360 GLE
1985 340 GL_______1986 340 1.4
1985 360 GLS______1995 940 SE 2.3 Turbo Estate (daily)
1987 340 GL 1.7

antoni
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Joined: 26 Jun 2010 06:04 pm

Re: Camber on rear wheels

Post by antoni » 15 Jul 2010 06:55 pm

I am a vaj queen and on my previous golfs/polos i have done the camber mods.

As long as you only use one washer and check bolt tightness every now and then, you should be ok

If you die though, you never herd of me sm2

mat_91
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Re: Camber on rear wheels

Post by mat_91 » 15 Jul 2010 08:16 pm

hmm i have heard of this and i know its been done for a long time but i just dont know if i could trust it my self as after all the hub to axle face is what makes the strength
not the bolts rely
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volvodspec
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Re: Camber on rear wheels

Post by volvodspec » 15 Jul 2010 08:44 pm

i agree a pair of rings is not the way to do it; this will eventually overload the bolts holding the hub in place.

a machined spacer representing the exact contact surface between hub and axle is what you need, the tricky bit about this is that the spacer has to be machined at a slight slope to get the camber adjustment.

this will not effect the mounting in any way, the bolts can cope with the slight mis-angle and the contactsurface between axle and hub where it thanks its strength too is kept.

i don't agree on the bit that all 300 rear axles are enormously out of alignment after a few hard pullups, it's mostly bumping the rear wheel into something that gets it i've had numorous 300's on a laser alignment test and none of them were out of factory spec (including a 360 with 225000km wich was still exactly at factory spec!!)

Ride_on
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Re: Camber on rear wheels

Post by Ride_on » 16 Jul 2010 12:10 am

volvodspec wrote:i agree a pair of rings is not the way to do it; this will eventually overload the bolts holding the hub in place.
i don't agree on the bit that all 300 rear axles are enormously out of alignment after a few hard pullups, it's mostly bumping the rear wheel into something that gets it i've had numorous 300's on a laser alignment test and none of them were out of factory spec (including a 360 with 225000km wich was still exactly at factory spec!!)
I haven't seen one in spec (Toe-in) for at least 10 years, except perhaps Nimmiz's low miler. As I've said above if its visible its out of spec.

You really got toe-in measured and it was <+/-0.16 deg of 0?
1980 345 DL_______1987 360 GLE (project car restored to GLT spec and B230FT'd)
1984 360 GLT______1987 360 GLT
1983 360 GLS______1989 360 GLE
1985 340 GL_______1986 340 1.4
1985 360 GLS______1995 940 SE 2.3 Turbo Estate (daily)
1987 340 GL 1.7

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SteveP
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Re: Camber on rear wheels

Post by SteveP » 16 Jul 2010 09:34 am

I really don't think it happens that much either to be honest, my black 360 GLT which had a hard life presumably towing was the only car 300 I've had with visibly excessive camber due to wear. My blue 360 GLT had bent on one side severely, but had a very easy (low mileage of 70k) life - I would assume this had been kerbed as it looked almost as if it had zero camber, I doubt it would take much to bend the hub end mounts and easily done in the snow.

My old 343 and current low mileage GLS are absolutely spot on - it's pretty easy to tell visibly imo, especially with mud flaps lol
1989 - Volvo 360 GLT
1985 - Volvo 360 GLS
2008 - Volvo S60 SE Lux

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Chris_C
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Re: Camber on rear wheels

Post by Chris_C » 16 Jul 2010 10:36 am

Are we talking about toe in or camber here... both terms seem to be floating about randomly.

My car (on both the 340 and the 360 axle) has always showed 0 toe on the laser aligners. The 2 degrees of camber that is stock is *very* visible to the eye.
'89(G) 340 GLE B172k
'03 S60 D5 SE, '91 (J) MX5, 1954 Cyclemaster
Ex:
'89(F) 340 GL F7R (ex B172k) - Fake -> SBKV 300 Runner Up 08, 12; '91(H) 340 GL B14.4E - Kar; '88(F) 360 GLT B200E - Jet -> BKV 300 Runner Up 09; '89(G) 360 GLT B200E - Beast

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