Ok here is my idea. loosen the nut until you can turn the adjustment bolt freely and then tack it in place. Weld a wrench or bar to the bolt head so it will stick up into the cockpit or trunk I can’t remember which. Weld a plate in vertically so it is parallel to the movement of the bar. Drill holes through the plate and bar so you can put a pin through them. Calibrate the settings at the alignment shop and then gloat about being able to change rear camber and toe faster than anyone at the track. You most likely need to drop the sub-frame to do this and maybe relocate some brake lines but I’m sure it could work.
RTAB bushing that won't stay put
FishMan
#23
That wouldn’t work… The weld on tabs would carry the suspension loads and surely fail; as designed, they are only there for adjustment purposes and should not carry any load after tightening the bolts.
FishMan
#25
Machined or bent, they aren’t designed to carry suspension loads. They are only there for adjustment purposes and the tightened bolt carries the load. If they would take the load, your settings would constantly change as there is too much slop in the setup.
jtower
#26
on a somewhat related note, while replacing the halfshaft this morning i discovered that two of the four trailing arm nuts were only fingertip tight, and who knows where the eccentrics had rotated to (my alignment guy didn’t mark them as i had asked). man what i wouldn’t give for an e36 rear suspension design…
SkiFree
#27
While this is true, the fact that if they are machined or bent DOES make a difference with this design, and while IE is doing a new design the following illustration should very much be taken into account for the time being.
jlevie
#28
A radius on the inner edge of the eccentric washer eliminates the advantage of the machined adjuster plate.
I am of the opinion that the adjusters move because the inner sleeve of the bushing rotates with the trailing arm. If rotational force isn’t being applied to the adjuster, it won’t change or loosen. If the inner sleeve doesn’t move, no rotational forces will be applied to the adjuster . But if it does the adjuster will move and/or loosen.
SkiFree
#29
Your correct on the second part but not on the first.
A machined part offers much tighter tolerances than a bent counterpart. If you have a loose fit between the eccentric washer and the side walls of the bracket then that will only be magnified under load.
NASA144
#30
I have the AKG weld-in and poly bushings… no probs with three DE4 weekends!
But… just curious here. I didn’t weld in place the camber plates for enough camber, only getting 2.8 max. Can I use the eccentrics with the weld-ins??? Anyone doing this?
ps: I filed down the inner radius of the plates… didn’t want the washers to deform.
jlevie
#31
A good frame shop can bend the trailing arms to get good camber. Take the car to the shop with the adjusters maxed out and ask for 4deg of camber in that configuration. When set for 3deg of camber the adjusters will close to the middle of their range and that will reduce the axial misalignment of the bushings.
Before doing that check the position of the toe adjusters when the rear wheels are set for 1/16" total toe in. They should be about in the middle of the adjustment range. If they aren’t the trailing arms are bent and need to be replaced. I don’t know of any way to bend the arms to correct toe errors.
Freddie
#32
I’m planning on ordering my rtab kit on monday to finish my SpecE30. At this point after reading the thread is the performance advantage worth the effort? I’m starting to consider just putting the bushings in without the adjusters? Any thoughts?
Ranger
#33
Is precisely what worth the effort?
I would either install eccentric rtabs or the weld-on kit. If you do neither then you’ll end up with zero adjustability. Both solutions have their warts tho.
If I were to do this again I would still do the weld on kit, but I would consider using OEM concentric bushings with the idea that the additional compliance would help the eccentrics stay put when under load, or I would use harder bushings and do some work on them to ensure that the cylindrical pivots inside of the bushings rotated freely.
If you install any kind of adjustable system, be sure to mark the positions well. That way you’ll know immed if there is a problem, and no matter what the problem is theres a way to resolve it.
2 venders say they’ll have improved weld on kits soon. Thats pretty significant.
Since I rigged up a way to keep my right toe weld on eccentric to stay put, I’ve made it thru a weekend with no change in it’s position. Before imagineering that solution, I couldn’t make it thru a session w/o it changing.
jlevie
#34
[quote=“Ranger” post=59447]Is precisely what worth the effort?
I would either install eccentric rtabs or the weld-on kit. If you do neither then you’ll end up with zero adjustability. Both solutions have their warts tho.
If I were to do this again I would still do the weld on kit, but I would consider using OEM concentric bushings with the idea that the additional compliance would help the eccentrics stay put when under load, or I would use harder bushings and do some work on them to ensure that the cylindrical pivots inside of the bushings rotated freely.[/quote]
I’ve tried using the OE bushings and they don’t help with retaining the settings. I attribute that to the fact that the OE bushings don’t rotate over the inner sleeve. Judging by the scarring on the sleeves and the inner face of the adjusters it was pretty obvious that the sleeves had been moving with the trailing arms.
The AKG bushings seem like they work better, but their current product uses aluminum sleeves. Steel sleeves would be better. My current configuration uses AKG bushings and home-made adjuster bolts that employ aircraft twelve-point bolts and nuts. The previous adjuster bolts had thread failure (they were only grade 5). My new bolts have full thread since I disposed of the outboard eccentric and the bolts are stronger than a grade 8. Once I am satisfied with the rear alignment I am going to put a short weld bead on each eccentric to reduce the load on the bolts. While that should keep the adjustments from drifting, it does have the down side of requiring the subframe to be dropped and the welds cut free before any future adjustments. But that is a small price to pay to prevent an adjuster from coming loose during a race weekend.
Elephant4
#35
For what its worth I don’t use the adj rtabs, I personally don’t think its worth the effort. Mind you I’m extremely lazy when it comes to setup. I set and forget.
Freddie
#37
I guess my question was not clear. In terms of lap times(versus potential alignment and bolt failure problems), is there a big difference in cars with adjustable rear ends to cars without. I’m going to race norcal…am I going to have the potential to be competitive with the front runners w/o the adjusters?
jtower
#38
depends on what your non-adjustable alignment numbers are, no two cars are the same especially after 25 years. if they’re spot on then you’re fine, if not you’ll have sub-optimal handling characteristics and/or tire wear.
Ranger
#39
+1
Near as I can tell you don’t know what you have, and you don’t know what you want.
The only way to know what your rear alignment will be with concentric bushings is to assemble it and see. Then only you can decide whether or not you can live with the result. Folks have different ideas as to what the ideal alignment is. One guy might have -2 camber and another might have -3. One guy might have neutral toe and another might have 1/8" toe in. You can either put in a non-adjustable system and hope for the best, or put in an adjustable system and, well, hope for the best.
Ranger
#40
[quote=“jlevie” post=59451][quote=“Ranger” post=59447]Is precisely what worth the effort?
I would either install eccentric rtabs or the weld-on kit. If you do neither then you’ll end up with zero adjustability. Both solutions have their warts tho.
If I were to do this again I would still do the weld on kit, but I would consider using OEM concentric bushings with the idea that the additional compliance would help the eccentrics stay put when under load, or I would use harder bushings and do some work on them to ensure that the cylindrical pivots inside of the bushings rotated freely.[/quote]
I’ve tried using the OE bushings and they don’t help with retaining the settings. I attribute that to the fact that the OE bushings don’t rotate over the inner sleeve. Judging by the scarring on the sleeves and the inner face of the adjusters it was pretty obvious that the sleeves had been moving with the trailing arms.
The AKG bushings seem like they work better, but their current product uses aluminum sleeves. Steel sleeves would be better. My current configuration uses AKG bushings and home-made adjuster bolts that employ aircraft twelve-point bolts and nuts. The previous adjuster bolts had thread failure (they were only grade 5). My new bolts have full thread since I disposed of the outboard eccentric and the bolts are stronger than a grade 8. Once I am satisfied with the rear alignment I am going to put a short weld bead on each eccentric to reduce the load on the bolts. While that should keep the adjustments from drifting, it does have the down side of requiring the subframe to be dropped and the welds cut free before any future adjustments. But that is a small price to pay to prevent an adjuster from coming loose during a race weekend.[/quote]
Re. OEM Adjusters and non-rotating sleaves. Interesting, thx for the innfo.
Re. Aluminum sleeves. Chuck Baader mentioned this to me some months ago. He’s pretty sure that his bushings have steel sleeves but IIRC there was uncertainty as to whether that design was available anymore. I suppose we could buy AKG bushings and then fab steel sleeves for them. I think Chuck put a zerk fitting into his so he could get some grease in. If we fabbed our own sleeve it wouldn’t be a big leap to install a zerk fitting too.
Re. Welding the eccentric. I’d do this except I’m worried that I’d check it 10X to make sure it was perfect, tack the eccentric in place, and then my alignment would be a little wrong and I’m be stuck in this quandry of whether or not it was enough wrong to go thru the monumental hassle of removing the rear subframe and redoing it.
Removing the subframe wouldn’t be such a hassle if I cut holes in the bottom of the trunk and put studs into the diff. I don’t remember who’s idea that was, but I like it.
The way I imagineered my single problematic bushing, I can still adjust the eccentric even tho there’s another machanism holding it in place. Hopefully it will prove successful long term.