View Full Version : 3-Link rear axle cockeyed
spluhar
06-22-2023, 08:09 AM
I bought a completed roadster, and have been messing with the details to make it mine. I did the front end alignment (castor was way off and different from left to right) and took it for a ride. The steering wheel is turned 30 degrees in my hands as I drive straight. I did some measuring and the left side wheel base is 1" less that the right side. I bought a laser level/square and checked the rear axle (Moser/3 Link) and it's shifted forward on the left side by 1 full inch. I pulled the wheel off and do not see anything obvious. Any idea's? Thank you.
btw, driver's side is 89 1/4", passenger's side is 90 1/4".
ggunter
06-22-2023, 08:13 AM
Does it have the fixed or adjustable bottom torque arms om the rear?
GoDadGo
06-22-2023, 08:14 AM
Here is a possible solution if you need to adjust the thrust angle of your 3-link:
https://www.spohn.net/shop/Factory-Five-Racing-MK3-MK4-Roadster/Adjustable-Rear-Lower-Control-Arms-with-Del-Sphere-Pivot-Joints.html
Hope This Helps & Good Luck!
Indy Shu
06-22-2023, 09:22 AM
For the front you can adjust your outer tie rods equal but opposite directions until the steering wheel is straight. I'd suggest to start with 1 full turn. I don't think the rear affects the front alignment much. My car was about 3/4" difference on wheelbase and I corrected that when I replaced the lower control arms with a set of adjustable arms from Breeze https://breezeautomotive.com/shop/rod-end-rear-lower-control-arm-kit/. Rod-end type control arms improve handling too. The LCA's that Go Dad referenced look nice too.
Have you taken it to an alignment shop? I suspect that the front-end is likely out of whack as the rear is typically a fixed geometry with the three-link, unless there are adjustable LCA installed or the frame mounts are wrong (not likely).
spluhar
06-22-2023, 09:35 AM
Does it have the fixed or adjustable bottom torque arms om the rear?
Fixed
spluhar
06-22-2023, 09:37 AM
I've not taken it to an alignment shop. Front end it perfect. It's definitely the rear. I used a lazer square and aligned it with the frame rail. The rear is 1" further forward on the driver's side.
Are the rear LCAs the same length on both sides?
spluhar
06-22-2023, 09:53 AM
Are the rear LCAs the same length on both sides?
yes.
spluhar
06-22-2023, 09:56 AM
It may be the brackets welded onto the Moser axle. My eyeball says that the ds is forward at the bottom and the ps is rearward at the bottom. I'll have to take a closer look this evening when I have my next chance to get into it.
If the brackets are off, this may be an easy solution for you: https://breezeautomotive.com/shop/rod-end-rear-lower-control-arm-kit/
The same as what GoDadGo recommended, but from one of our sponsored vendors.
FLPBFoot
06-22-2023, 12:46 PM
Could be the brackets on the axle or on the frame. My shop did a four wheel alignment and the rear was off so had to go with the Breeze adjustable lower control arms and problem solved.
spluhar
06-22-2023, 03:36 PM
Seems like that's the answer then. Adjustable control arms it is. Thanks all!!!
michael everson
06-22-2023, 04:24 PM
Moser had a run of rearends that were welded wrong. You may have gotten one of them.
Mike
RoadRacer
06-22-2023, 04:38 PM
I keep going back to the first words in this thread "I bought a completed roadster"...
How many miles were driven this way? I mean an inch isn't a lot, but the rear would be trying to go sideways all the time. Glad you caught it!
spluhar
06-22-2023, 04:52 PM
I bought it a few months ago with 200 miles on it. Including the 150 mile drive home, Ive only put a couple hundred since. I'm just going to go through the whole thing and improve whatever I dislike or find messed up. One step at a time.
GoDadGo
06-22-2023, 06:24 PM
I bought it a few months ago with 200 miles on it. Including the 150 mile drive home, Ive only put a couple hundred since. I'm just going to go through the whole thing and improve whatever I dislike or find messed up. One step at a time.
Good Luck & You've Got This!
spluhar
06-22-2023, 06:41 PM
Thanks!
CraigS
06-23-2023, 06:47 AM
Spend a lot of time being really carefull w/ your wheelbase measurements. I tried to do that once and it was a trial. You can't measure to the front wheels as they move forward and back quite a bit w/ the smallest steering wheel movement. I gave up on the measuring length and instead measured angle.
186231186231
I used the above rig after I upgraded to irs. You can do similar w/ a straight piece of wood trim. Hold it against the rear wheel/tire and lay the end near the front wheel on something about 5-6inches tall. Then measure in from the wood to the 4 inch frame tube just behind the front wheel. That distance should be equal left and right.
GoDadGo
06-23-2023, 07:34 AM
I did the same thing as CraigS to verify my thrust angle prior to getting the car aligned.
In retrospect, we all should likely check our cars this way as we build them.
The string method works also, but Laser Levels are more fun.
michael everson
06-23-2023, 08:15 AM
To check it accurately, measure from the lower control arm mount to the axle tube on both sides.
Mike
spluhar
06-23-2023, 03:52 PM
Update: Factory Five confirmed that there was a problem with some Moser axles that came through. One of the control arm brackets were rotating while they were set in the jig to weld. While on the phone, I took their requested dimensions to confirm that this is, in fact, one of the bad axles. I will be sending FFR detailed dimensions, which will be forwarded to Moser. Moser will then be sending to me, a bracket that will relocate the lower control arm hole to the proper location. Thank you for all of your comments. Accuracy has been priority since I did the original front end alignment, and will be a priority during the follow up with Factory Five.
Update: Factory Five confirmed that there was a problem with some Moser axles that came through. One of the control arm brackets were rotating while they were set in the jig to weld. While on the phone, I took their requested dimensions to confirm that this is, in fact, one of the bad axles. I will be sending FFR detailed dimensions, which will be forwarded to Moser. Moser will then be sending to me, a bracket that will relocate the lower control arm hole to the proper location. Thank you for all of your comments. Accuracy has been priority since I did the original front end alignment, and will be a priority during the follow up with Factory Five.
That's good news! Gotta love FFR customer service.