4 link setup question

Mr. Demeanor · #1 (**permalink**) 12-09-2019, 08:27 AM

I have an older (mid 1990's) build replica of unknown origin. Bought it about a year ago and just getting going on getting some of the goofy stuff worked out.

While making some adjustments I discovered the frame mount spacing for the four link is different on the passenger side vs the divers side. The passenger side mounts are 1-1/8" closer together. This has to be causing some twisting/binding but I am wondering if this could have been done on purpose. Would this act to reduce squat on the passenger side under acceleration or did someone just completely screw up?

xlr8tr · #2 (**permalink**) 12-09-2019, 04:45 PM

hard to say with the one picture of just one side: do you have a picture of the other side? In general, from working on mine and reading a fair bit on this, I've never seen where there is a planned difference from one side to the other. In my experience, given we have VERY short links, very small changes in link angle, link length, whether the two links are parallel or converge etc etc make VERY big handling differences. 1 1/8" difference is massive IMHO.

Gaz64 · #3 (**permalink**) 12-09-2019, 05:11 PM

Left hand drive cars are great as drag cars with locked or spool diffs, but the drivers weight on the left side and a more normal street diff just invites the right hand wheel for traction loss.

Changing the roll centre by moving the top arm pivot point down hopefully evens out the traction under load.

Probably what the previous owner was chasing.

Not as obvious with RH drive cars, but then the left front wheel gets light earlier.

Sometimes having your cake is harder than one thinks.

Gary

Mr. Demeanor · #4 (**permalink**) 12-10-2019, 07:58 AM

I think someone forgot to measure twice the more I look at this.

Mr. Demeanor · #5 (**permalink**) 12-10-2019, 09:55 AM

Quote:

Originally Posted by xlr8tr

hard to say with the one picture of just one side: do you have a picture of the other side? In general, from working on mine and reading a fair bit on this, I've never seen where there is a planned difference from one side to the other. In my experience, given we have VERY short links, very small changes in link angle, link length, whether the two links are parallel or converge etc etc make VERY big handling differences. 1 1/8" difference is massive IMHO.

The other side looks the same just spaced between the bolts is different.

byron w · #6 (**permalink**) 12-10-2019, 10:33 AM

Mr. Demeanor,

Please send a picture of the other side

Byron

Mr. Demeanor · #7 (**permalink**) 12-10-2019, 02:11 PM

Quote:

Originally Posted by byron w

Mr. Demeanor,

Please send a picture of the other side

Byron

I would have to pull the wheel off. Looks just like this side but the mounts are 1-1/8" closer. The bottom mounts are the same, the top on the passenger side is lower.

xlr8tr · #8 (**permalink**) 12-11-2019, 02:06 PM

without seeing the picture, think of the difference between how the passenger versus drivers side top bar moves when the suspension goes up and down- while cornering for example. The passenger side upper bar, being angled down much more than the drivers side, will pull the axle forward as the suspension compresses in a left hand corner. In a right hand corner, the top bar drivers side is pretty level so the same amount of suspension compression will not create the same amount of "pull forward" axle movement. This will also be noticed under braking and acceleration (basically any suspension movement). If it is like my car was before i fixed it, when acceleration causes the rear end to squat, the care will want to turn to the right, as the compressing passenger side will "rear steer" the axle more than the drivers side. The reverse will happen in braking. None of this left to right difference is a particularly good feature!! :-)

Mr. Demeanor · #9 (**permalink**) 12-11-2019, 07:34 PM

The car goes surprisingly straight but I am rebuilding the entire suspension. It has a Mustang II front end and all the bushings etc are shot. Instead of rebuilding it I bought a complete tubular front end from Speedway. I noticed this 4 link problem while adjusting the ride height. There is a significant difference in the adjustment on the right vs left side coil over to get it to sit level.