VR457
01-03-2012, 04:07 AM
Intro: This modification is for adjusting the rear camber on the VR4. Thanks for the original writeup goes to Gly and others on OZVR4 but I felt that we could do with the information here on CVR4 in an easy to access place.
Formula and conversion: A whole degree is 60 minutes. So, 1 degree 30 minutes means 1.5 degrees in decimal terms. In this writing the decimal figures will be in brackets.
Issue: My 4 wheel alignment results showed rear wheels had a negative camber of 2 degrees 11 and 2 degrees 26 (2.18 – 2.43). Now the recommended figures are between 30 mins and 1 degree 30 mins (1.5 – 0.5 degrees) – so this was clearly out. The cause of this excess camber was sagging rear springs due to heavy equipment in the boot (for others, lowering springs result in the same effect). The effect was to wear out the rear wheel on the inside. I had a fail on the previous MOT for this and was shocked to see that it could have blown out at any time / speed.
Time required: 1 hour
Difficulty: Easy, with moderate level of concentration.
51608
Tools: As shown in the picture - 2 x 17mm spanners, 1 x 14mm spanner, a small screwdriver to align the washers with, a brush to clean the area where washers will sit, 8 bolts, 8 ring washers and a number of oversized washers.
Bolt and washer specification: Bolt – M10 x 35mm with 1.25mm pitch thread. Quality of bolt should be grade 8.8 though others have suggested that a lower A2 grade will suffice (chart http://www.k-tbolt.com/bolt_chart.html shows the data for this). The ring washers are to ensure the bolt does not come undone and goes onto the bolt before inserting into the D bracket.
The oversized washers are what are required to achieve the camber mod. The quality of the washers is important too though as they will be fastened tight that might not be so critical an issue. The advice on OZVR4 is to go for multiple washers rather than a single thick piece due to shock absorption and dispersal properties.
Oversized washers info: Gly on OZVR4 suggested 6mm equated to 1.5 degree camber. I ended up using washers totalling 7 mm thickness so my camber was reduced by an estimated 1.75 degree, from (2.18 – 2.43) to (0.43 – 0.68), the minimum recommended level. The only real way to check how much is get it measured properly.
Procedure: Jack up the car, axle stands and take the wheel off. You can leave the wheel on, as I did but if the bolts are stiff then you will need the space to manoeuvre a larger wrench.
51609
51610
51611
51612
Using the two 17mm spanners, undo bolt 1 slightly. Then undo bolts 2 and 3. You can then take bolt 1 out. The D bracket is spring loaded so this method worked best for me. Then undo bolts 4 and 5 and take the D bracket out. Leaving bolt 1 in did not make the job easier for me; I wasted an hour and a half before finding the way I described above. Clean the washer and dirt off the bolt.
With the bracket off, brush dirt off it and wipe the area where the oversized washers will sit. Picture 4 and 5 show this area as a shiny surface.
51613
Put bolt with ring washer on through the bracket hole, pack the required number of washers behind the bracket and hand screw the bolt back into place. Put the other bolts in place and then tighten bolts 4 and 5. Tighten up bolts 2 and 3 keeping the D bracket pulled down. Once secure, then attempt to refit bolt 1 in it’s place. Picture 6 shows the gap, which means the arm needs to be aligned and then the D bracket pulled down into place before sliding the bolt in. Some strength is required for this, unless you are used to mechanic jobs so get help if you must.
Tighten up all the bolts, refit and tighten wheel, remove axle stands, lower car and pull handbrake!
Effect on handling: The back feels lighter and the wheels don’t seem to drag any more. The handling has become much lighter and faster and the car handles a lot better, even with aggressive turns. I now have understeer at the limit for the first time. The problems I am having are related to the front spring being too high so now the front end seems overly twitchy and very light. Under heavy braking from very high speeds the car front end starts dragging off the straight line. At high speeds it seems easy to lose the front end though it feels safer than before where the excess camber made the back end feel unsafe. Paradoxically this mod makes the car turn in better and faster, with the back less prone to sliding about.
Since my rear camber has been reduced to the minimum, I will increase it back to around 1 degree and think this will work out better for overall stability and handling.
Formula and conversion: A whole degree is 60 minutes. So, 1 degree 30 minutes means 1.5 degrees in decimal terms. In this writing the decimal figures will be in brackets.
Issue: My 4 wheel alignment results showed rear wheels had a negative camber of 2 degrees 11 and 2 degrees 26 (2.18 – 2.43). Now the recommended figures are between 30 mins and 1 degree 30 mins (1.5 – 0.5 degrees) – so this was clearly out. The cause of this excess camber was sagging rear springs due to heavy equipment in the boot (for others, lowering springs result in the same effect). The effect was to wear out the rear wheel on the inside. I had a fail on the previous MOT for this and was shocked to see that it could have blown out at any time / speed.
Time required: 1 hour
Difficulty: Easy, with moderate level of concentration.
51608
Tools: As shown in the picture - 2 x 17mm spanners, 1 x 14mm spanner, a small screwdriver to align the washers with, a brush to clean the area where washers will sit, 8 bolts, 8 ring washers and a number of oversized washers.
Bolt and washer specification: Bolt – M10 x 35mm with 1.25mm pitch thread. Quality of bolt should be grade 8.8 though others have suggested that a lower A2 grade will suffice (chart http://www.k-tbolt.com/bolt_chart.html shows the data for this). The ring washers are to ensure the bolt does not come undone and goes onto the bolt before inserting into the D bracket.
The oversized washers are what are required to achieve the camber mod. The quality of the washers is important too though as they will be fastened tight that might not be so critical an issue. The advice on OZVR4 is to go for multiple washers rather than a single thick piece due to shock absorption and dispersal properties.
Oversized washers info: Gly on OZVR4 suggested 6mm equated to 1.5 degree camber. I ended up using washers totalling 7 mm thickness so my camber was reduced by an estimated 1.75 degree, from (2.18 – 2.43) to (0.43 – 0.68), the minimum recommended level. The only real way to check how much is get it measured properly.
Procedure: Jack up the car, axle stands and take the wheel off. You can leave the wheel on, as I did but if the bolts are stiff then you will need the space to manoeuvre a larger wrench.
51609
51610
51611
51612
Using the two 17mm spanners, undo bolt 1 slightly. Then undo bolts 2 and 3. You can then take bolt 1 out. The D bracket is spring loaded so this method worked best for me. Then undo bolts 4 and 5 and take the D bracket out. Leaving bolt 1 in did not make the job easier for me; I wasted an hour and a half before finding the way I described above. Clean the washer and dirt off the bolt.
With the bracket off, brush dirt off it and wipe the area where the oversized washers will sit. Picture 4 and 5 show this area as a shiny surface.
51613
Put bolt with ring washer on through the bracket hole, pack the required number of washers behind the bracket and hand screw the bolt back into place. Put the other bolts in place and then tighten bolts 4 and 5. Tighten up bolts 2 and 3 keeping the D bracket pulled down. Once secure, then attempt to refit bolt 1 in it’s place. Picture 6 shows the gap, which means the arm needs to be aligned and then the D bracket pulled down into place before sliding the bolt in. Some strength is required for this, unless you are used to mechanic jobs so get help if you must.
Tighten up all the bolts, refit and tighten wheel, remove axle stands, lower car and pull handbrake!
Effect on handling: The back feels lighter and the wheels don’t seem to drag any more. The handling has become much lighter and faster and the car handles a lot better, even with aggressive turns. I now have understeer at the limit for the first time. The problems I am having are related to the front spring being too high so now the front end seems overly twitchy and very light. Under heavy braking from very high speeds the car front end starts dragging off the straight line. At high speeds it seems easy to lose the front end though it feels safer than before where the excess camber made the back end feel unsafe. Paradoxically this mod makes the car turn in better and faster, with the back less prone to sliding about.
Since my rear camber has been reduced to the minimum, I will increase it back to around 1 degree and think this will work out better for overall stability and handling.