How to adjust rear ride height?

[FFRWRX]

I know, this seems like a dumb question.....even to me.

My car was at a ride height of about 4". I wanted it a touch higher. F5 recommends 4.5" so a little higher would be good to prevent scraping the front piece. I adjusted the fronts OK; not easy, but got it done. With the car raised by the frame to let the suspension droop, after a couple turns of the spring perch the spring is compressed and it gets hard to turn. But, got it done.

But the rear is another story. Yes, I could turn the spring perches, but just barely. The spring seems to be compressed enough to make it extremely difficult to turn the perch. The car is lifted by the frame, but the suspension is not drooped much. You can see in the picture with the tire off the ground the lower control arm is roughly parallel with the ground. Is that normal or should it go down lower? I pulled on it but it seems to have hit a pretty solid stop.

Screenshot 2022-11-10 at 4.03.02 PM.jpg

I thought maybe removing the coilover lower mount bolt would help, but the bolt won't come out. I hit it with a hammer and it didn't move. I could hit it a lot harder, but it told me that there is something binding up the bolt. Only thing that comes to mind is the suspension won't go lower and the coilover is pushing hard on it, so binding up that lower bolt. I thought maybe the shock hit its limit of travel and kept a lot of load on the spring. That would explain the spring mount being hard to turn, but not the bolt not coming out.

Thoughts?

Rick

[Hobby Racer]

You are most likely at the shocks max extension. What mounting hole are you using at the top of the shocks? There are two holes in the mounting tabs, 1 for street that allows more ground clearance and one for track that drops the car down for handling.

[FFRWRX]

Thank you.

The top mount is on the lower hole. But the hole above that one has a longer bolt that goes through another frame member, but doesn't really matter since I'm using the lower one.

I thought I might be at the extension limit of the shock, but then it shouldn't be that hard to knock the lower shock mounting bolt out. If that's true, lifting up the wheel a bit should ease the load on it.

I thought taking the coilover off and adjusting it on the bench might be easier than struggling with it in the car. I'll give it a shot.

Rick

[FFRWRX]

Got the bolt out and I know why it was so tight. I slowly raised the car from tire on the ground while hitting the bolt. It moved at one point, but was still not easy to tap/hammer out. Here is a picture of the shock setup:

Screenshot 2022-11-10 at 7.59.28 PM.jpg

The shock angles forward at the top, and the spindle area where it mounts is vertical, maybe even tilted back a bit. So the yellow part was basically jammed into the spindle mount due to the angle it is on.

I thought maybe the upper forward link, just visible in the picture, needs to be shortened a bit to rotate the spindle assembly to line up with the shock a bit better. But a bit more reading shows that it may not be a good idea to play with that as it will affect other suspension parameters. There was a large washer on one side of the shock mount, but since it was hitting on the shock body, not the pivot ball, it really wasn't doing anything good. I think that washer was jammed in there and pressed against the bolt, making it hard to remove. As long as the shock body can fit between the plates then smaller washers, just contacting the pivot ball, would be the way to go. I'll double check that the angle of the lower pivot ball in the shock is not at its limit of travel.

Rick

[FFRWRX]

I'll add a little more to this on what I've found since it may help someone.

The issue with it being very difficult to remove the lower shock mounting bolt was due to the angle the shock sits between the mounting plates on the spindle:

Screenshot 2022-11-12 at 6.10.00 PM.jpg

That picture is after I removed the shock, and the washers, and just fitted it back in. This next picture really shows the issue:

Screenshot 2022-11-12 at 6.10.37 PM.jpg

There was a small washer (the proper size to contact on the pivot ball only) on one side, but a large one on the other side, that was jammed in crooked. This was assembled by the previous owner and it is kind of surprising given the quality of the rest of the build. Must have been hammered in there.

It did seem strange that the angle of the shock was so mismatched from the lower mounting plates so I measured things. The lower mounting points for the control arms should be level and mine were about 2 degrees out. That makes the angle of the shock mounting plates worse, so I adjusted it. The shock is still on an angle compared with the lower mount, but with smaller washers now on both sides of the pivot ball it fits much better.

So finally got things sorted out and the suspension raised. It was easier to take off the wheel and turn the spring mount from the outside. I think I have the ride height where I want it now, just have to run it up and down the driveway a couple times to settle things.

Rick

[RPGs818SNA]

My manual says “Bolt the rear coil over to the spindle mounting bracket with the 0.125 inch spacer on the front side of the shock, 0.25 inch spacer on the back…”

rear shock mount.jpg

It looks like the spacers are designed to give the shock body room to fit between the bracket faces without interference, even though it’s at an angle with respect to the bracket. All 4 shocks are mounted like that with spacers top and bottom. It might be worth checking all of them for the right spacers.

Thanks for sharing so many helpful details on your build.

RPG

[RPGs818SNA]

I ran into the same problem as Rick today adjusting the rear ride height up to 4.5” by trying to turn the spring perches. I was trying to turn them without having to remove the bolts at the bottom of the shocks.

Like Rick, I first raised the tires off the ground. I had also greased the threads the last time I adjusted it, and that seemed to help. I tried to turn the perches with the FFR rivnut tool, but various things got in the way.

Two ways finally worked. The first was a combination of 2 Allen wrenches (3/16 & 5mm) in 2 perch holes turned at the same time. What worked better was a rubber strap wrench, after I had washed the grease off the perch and the strap. I hope I don’t have to adjust them again any time soon.

RPG

[Bicyclops]

I was struggling with shock adjustment too. Strap wrench helps a bunch, but what really helped was putting a thrust bearing under the perch instead of the supplied plastic washer. A set of 2 was $20 at Summit. I have another set for the front, but I'm not in a big hurry to disassemble until I want to change out the springs or adjust height again. I'm at about 5" and I have to come in and out of my drive at an angle and I still don't always clear. I wouldn't want to be any lower.


I was bottoming out too, the rear tires rubbing on the tubs when I hit a bump. I'm a bit heavy back there with dry sump and AWIC and all. I went to Eibach 425# springs and that cured it. That's when I put the thrust washers in. I was also getting a funny little sideways skip in a hard corner and that seems to be cured as well.

Ed

[idf]

Do you have the Summit PN for the thrust washers you used?

[Bicyclops]

Do you have the Summit PN for the thrust washers you used?

https://www.summitracing.com/parts/UPI-7917-101

Ed