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740 strut rotation

Renny_D

Renny_D

New member
Joined
Nov 12, 2002
Location
Northwet hilly land (West Linn)
Some one talked about gaining caster and camber by rotating the front strut mount bolt. Does any one who has done this have a picture? I'm very curious and I searched and could not find any pictures.

Thanks
Renny
 
strut mounting

I never heard of that. But there have been articles in Rolling which detail making the hole elongated or drilling a new hole so you can adjust the camber on the 740.
 
I have heard about knocking out the front stud, rotating the top mount towards the center of the car and drilling a new hole before. My 940 seems to eat the outside edge of the nearside tyre. I spoke to an inderpendant Volvo mechanic and it was done by Volvo to cure the tyre wear problem apparently.

I don't know what this gives you in degrees but it can't be a huge amount. You can only go so far before the mounting plate will hit the body. It might be possible to trim the edge off the mount but then the spring will end up touching.

If you need more castor Volvo made different length suspension tie rods ( the ones pointing backwards ) for the 940 so you could probably use these.
 
Steve940Estate said:
I have heard about knocking out the front stud, rotating the top mount towards the center of the car and drilling a new hole before. My 940 seems to eat the outside edge of the nearside tyre. I spoke to an inderpendant Volvo mechanic and it was done by Volvo to cure the tyre wear problem apparently.

I don't know what this gives you in degrees but it can't be a huge amount. You can only go so far before the mounting plate will hit the body. It might be possible to trim the edge off the mount but then the spring will end up touching.
Click to expand...

It'll give you ~-1 degree, which is a decent upgrade for nearly no work.
 
when you look at the top of the strutt you will notice 2 things:
- the damper piston and the 2 topmount bolts are exactly in line with each other (this means the L and R topmounts are symetrical)
- the hole in the shocktower is slightly oversized which means there is room to tillt the strutt slightly inward (negative camber) and slightly backward (more caster)

I personally would avoid drilling in the shocktower itself.

Remove the strutt, remove the topmount from the strutt, punch out the 2 bolts, hold the topmount against the inner shocktower to see how much you can shift it inward/to the back, let somebody mark the topmount with a feltpen. (notice that the topmount, once modified, will be dedicated to that side of the car! Do measurements to mirror the new holes on the other topmount. Drill new holes (don't oversize them!), pull the bolts in the (tight)holes (use a stack of oversized nuts, use the original nut to pull the bolts into the new holes, it's easy. when done remove the stack of oversized nuts ).
re-assemble the strutt, reinstall the strutt.
Repeat this for the other side of the car but this time use the measurements taken on the first adapted topmount to define where the new holes need to be drilled (remember: Mirrored!) on the second topmount. That way you ensure that both sides are geometrically the same (but mirrored).

While you're at it , lubricate the topbearings before reassembling the strutts.

To me this topmount mod was the single most satisfying mod i made on my car. It gave the front axel so much more mechanical grip, much like a BMW e30 with M-tech chassis. NO understeer. NO excess tirewear on the outer edges of the threads. (i must say i'm a bit of a 'kurvenjaeger' , if you do mainly straight highway driving this mod is probably not for you, if you're an auto-X-er you'll love it.)

costs: $0,- , some hour of wrenching and some elbowgrease ;-)

Note: if you start driving with these adapted topmounts you might at first experience a L/R steering wobble. This is caused by the tires not being worn to the new chassis settings. Eventually (after about 100miles) the tires will have worn to the new settings and the wobble will go away. When i installed brandnew tires there was no wobble either.

y1pANxNcGjvK0Ems89NmivahvRK8B9qpLK_Jeg8Aicz8rzbU1MVohm8hGGurr_XrIrScjgrt4DcCY8
 
Last edited:
I didn't realise it gave that much. I must do this before I fit some new tyres.
Thanks as well to Janspeed for describing what to do. The guy I talked to said he just re-drilled the top mount on the car and fitted a new standard bolt. It's much better to fit the original one if you can as it makes removing the strut in the future easier.

Another job I must do !
 
Wow that's the best description yet. I thought that I was redrilling the strut towers and I was thinking about how I was going to go about reinforcing the strut towers at the new hole location. I like your idea much better. How hard is it to knock out those bolts and what did you use? I have an air hammer but don't have the right bit. Lemme know and can you please post pics of the finished product on your car.

Thanks again
Renny
 
Janspeed said:
when you look at the top of the strutt you will notice 2 things:
- the damper piston and the 2 topmount bolts are exactly in line with each other (this means the L and R topmounts are symetrical)
- the hole in the shocktower is slightly oversized which means there is room to tillt the strutt slightly inward (negative camber) and slightly backward (more caster)

I personally would avoid drilling in the shocktower itself.

Remove the strutt, remove the topmount from the strutt, punch out the 2 bolts, hold the topmount against the inner shocktower to see how much you can shift it inward/to the back, let somebody mark the topmount with a feltpen. (notice that the topmount, once modified, will be dedicated to that side of the car! Do measurements to mirror the new holes on the other topmount. Drill new holes (don't oversize them!), pull the bolts in the (tight)holes (use a stack of oversized nuts, use the original nut to pull the bolts into the new holes, it's easy. when done remove the stack of oversized nuts ).
re-assemble the strutt, reinstall the strutt.
Repeat this for the other side of the car but this time use the measurements taken on the first adapted topmount to define where the new holes need to be drilled (remember: Mirrored!) on the second topmount. That way you ensure that both sides are geometrically the same (but mirrored).

While you're at it , lubricate the topbearings before reassembling the strutts.

To me this topmount mod was the single most satisfying mod i made on my car. It gave the front axel so much more mechanical grip, much like a BMW e30 with M-tech chassis. NO understeer. NO excess tirewear on the outer edges of the threads. (i must say i'm a bit of a 'kurvenjaeger' , if you do mainly straight highway driving this mod is probably not for you, if you're an auto-X-er you'll love it.)

costs: $0,- , some hour of wrenching and some elbowgrease ;-)

Note: if you start driving with these adapted topmounts you might at first experience a L/R steering wobble. This is caused by the tires not being worn to the new chassis settings. Eventually (after about 100miles) the tires will have worn to the new settings and the wobble will go away. When i installed brandnew tires there was no wobble either.

y1pANxNcGjvK0Ems89NmivahvRK8B9qpLK_Jeg8Aicz8rzbU1MVohm8hGGurr_XrIrScjgrt4DcCY8
Click to expand...

What's the advantage of this method over just punching the front bolt out, rotationg the mount, drilling a new hole. and using a standard 10mm bolt & nut?
 
I wish I had seen this thread before I just installed new springs and struts today. Maybe I'll go rent the spring compressor again and knock this mod out.
 
I wonder if anyone ever thought of selling modded top plates?, kind of like a drilled stock cam pulleys, you could wack out a template to drill stock plates and sell them on an exchange basis, send yours in they send modified ones back...
 
Poik said:
I wish I had seen this thread before I just installed new springs and struts today. Maybe I'll go rent the spring compressor again and knock this mod out.
Click to expand...

No need; just jack up the front end.
This mod does NOT involve the spring or top strut nut.
 
Janspeed said:
To me this topmount mod was the single most satisfying mod i made on my car. It gave the front axel so much more mechanical grip, much like a BMW e30 with M-tech chassis. NO understeer. NO excess tirewear on the outer edges of the threads. (i must say i'm a bit of a 'kurvenjaeger' , if you do mainly straight highway driving this mod is probably not for you, if you're an auto-X-er you'll love it.)
Click to expand...

I (and Martijn) were very impressed with the handling of your car, especially the grip of the front end, that was beyond all expectations. Never would have thought that a simple modification like this would be so effective!
We are going to do this with the 760 as well. Because that car has the early strut mounts (they look very much like a 240 strutmount!) it is probably a bit different but the same rules apply.
Very good writeup btw! :rockon:

Maybe my 240 can be modded like this as well :-P
 
Cool, I'll give it a whack and see what happens.

Also, just rotating the front bolt hole looks like it will give you more negative camber but less caster than offsetting both bolts.
 
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