Hi,
As part of restoration of the car, I'm going for a full underside refresh.
Since it's a cab, it already has the thicker 12mm rear arb/stabilizer/sway bar.
I had been eyeing an M3 rear ARB at 14.5mm but recently spotted a very good deal on an Eibach ARB at 16mm and have ordered it. The idea being a thicker ARB will provide a tighter ride.
However, I noticed that folks recommend that fitting a thicker ARB should be done in conjunction with lower link reinforcement kit, one like this https://www.turnermotorsport.com/p-3775 ... ement-kit/, which feels like another hassle.
So question is, given that there will be overall improvement everywhere, e.g. new bushes, springs etc. perhaps an upgraded ARB is not a big deal, especially considering the added hassle and that this'll really be a street car/cruiser.
Thoughts welcome.
Rear anti roll bar - is Eibach or M3 worth the upgrade?
Moderator: martauto
IMHO do things in order (which it looks like you are doing) and at this point in time I don't see the point in reinventing the wheel. Get it back to standard arms and bushes wise, fit a Bilstein B12 kit (B8 shocks and Eibach springs) then put the Eibach ARB kit on front and rear.
That has been the accepted standard for years as a street car. I drove mine daily for 10 years on the original Alpina Bilstein's and then (very similar) Koni yellow setup and it was fine. Mine will be going back to the Bilstein/Eibach setup above and it is all sat on the shelf waiting. I may reinforce the mounts but I see no real need if the original metalwork is sound.
IMHO don't just do the back, keep it in balance. Just the back will make it more tail happy and not what you want on a street car. I always did both ends on the E30 and will do same again.
Eibach ARB is a worthwhile change and works well with the B12 kit that it is designed for. H&R ARB is slightly stiffer and better paired with the stiffer H&R springs.
That has been the accepted standard for years as a street car. I drove mine daily for 10 years on the original Alpina Bilstein's and then (very similar) Koni yellow setup and it was fine. Mine will be going back to the Bilstein/Eibach setup above and it is all sat on the shelf waiting. I may reinforce the mounts but I see no real need if the original metalwork is sound.
IMHO don't just do the back, keep it in balance. Just the back will make it more tail happy and not what you want on a street car. I always did both ends on the E30 and will do same again.
Eibach ARB is a worthwhile change and works well with the B12 kit that it is designed for. H&R ARB is slightly stiffer and better paired with the stiffer H&R springs.
Thank you. Currently rocking Bilstein B4s, with Eibach sports pro springs to go in fitted.flybynite wrote: ↑Tue Oct 17, 2023 8:12 pmIMHO do things in order (which it looks like you are doing) and at this point in time I don't see the point in reinventing the wheel. Get it back to standard arms and bushes wise, fit a Bilstein B12 kit (B8 shocks and Eibach springs) then put the Eibach ARB kit on front and rear.
That has been the accepted standard for years as a street car. I drove mine daily for 10 years on the original Alpina Bilstein's and then (very similar) Koni yellow setup and it was fine. Mine will be going back to the Bilstein/Eibach setup above and it is all sat on the shelf waiting. I may reinforce the mounts but I see no real need if the original metalwork is sound.
IMHO don't just do the back, keep it in balance. Just the back will make it more tail happy and not what you want on a street car. I always did both ends on the E30 and will do same again.
Eibach ARB is a worthwhile change and works well with the B12 kit that it is designed for. H&R ARB is slightly stiffer and better paired with the stiffer H&R springs.
FYI on the fronts the cab ARB is 21mm, Eibach is 20mm, so I think fronts are fine already.
You should be fine but conventional 'wisdom' is that the B4 are best paired with the Mtech springs. The Eibach pro are best paired with the B8 shorter shock absorber (as contained in the B12 kit) Just something to keep in the back of your head in case you get problems
If you want to 'tighten' the handling then you might find reducing the front ARB by 1mm beneficial but there is no harm trying rear only and leaving the front given it is a cab.
Not wishing to hijack a thread but I have Bilstein B'4s and Eibach springs on the front of my 316i and while great on smooth surfaces the car does bottom out roughly on poor terrain. There are no bump stops on the shocks but some opinion is that these bump stops are inside in the shock. Does anyone know if that is the case for the Bilstein B4's?
Yes they will have some sort of stop at the bottom which is why they are not broken each time you bottom them out but how long they will last is another thing.Contours wrote: ↑Wed Oct 18, 2023 12:53 pmNot wishing to hijack a thread but I have Bilstein B'4s and Eibach springs on the front of my 316i and while great on smooth surfaces the car does bottom out roughly on poor terrain. There are no bump stops on the shocks but some opinion is that these bump stops are inside in the shock. Does anyone know if that is the case for the Bilstein B4's?
Performance shocks have an extended external bump stop that actually acts as part of the suspension rebound under full deflection. Bilstein certainly use this.
B4 on any car have never been recommended with lowered springs, You can get away with them on the E30 with the mild lowering of the Mtech springs but not the greater lowering of the Eibach pro or H&R springs.
B8 are perfectly acceptable for street use and the correct piston length for the lowered springs. (B6 and B8 have same damping level just differing piston length)
Many thanks for your reply--flybynite, that does explain it. I would have thought the m40 engine being a bit lighter that it wouldn't be as jarring but there it is, have to keep an eye out for every divot on the road.
i would pair a rear 16mm bar with at least a front 23/24mm but you could test it out to see if there is a bias to oversteer when pushing hard around a constant corner . When i had 24mm front and 16mm rear (Whiteline) it was pretty much perfect neutrality with an Eibach kit. The spring rate Front to Rear will drive the suitability of the front and rear bar sizes and the links also come into it regarding how much compliance they have.
The rear 16mm will eventually tear up the mounts on the trailing arm and chassis side at some point as that happened to me, there are some reinforcement kits available that will address this and i highly recommend doing this in advance as its its much easier.
Where possible i would opt for adjustable bars (multiple hole locations) and i would try and avoid the links with spherical rod ends unless they are protected with a rubber boot otherwise they will chew out and create a knocking noise.
The rear 16mm will eventually tear up the mounts on the trailing arm and chassis side at some point as that happened to me, there are some reinforcement kits available that will address this and i highly recommend doing this in advance as its its much easier.
Where possible i would opt for adjustable bars (multiple hole locations) and i would try and avoid the links with spherical rod ends unless they are protected with a rubber boot otherwise they will chew out and create a knocking noise.
E30 325is with M20B31
Great shoutout on reinforcement. That too was my conclusion and in the end decided not to pursue new ARBs. I’m hoping that all new suspension parts will automatically provide a much better experience without any upgrades.reggid wrote: ↑Tue Oct 24, 2023 10:17 pmi would pair a rear 16mm bar with at least a front 23/24mm but you could test it out to see if there is a bias to oversteer when pushing hard around a constant corner . When i had 24mm front and 16mm rear (Whiteline) it was pretty much perfect neutrality with an Eibach kit. The spring rate Front to Rear will drive the suitability of the front and rear bar sizes and the links also come into it regarding how much compliance they have.
The rear 16mm will eventually tear up the mounts on the trailing arm and chassis side at some point as that happened to me, there are some reinforcement kits available that will address this and i highly recommend doing this in advance as its its much easier.
Where possible i would opt for adjustable bars (multiple hole locations) and i would try and avoid the links with spherical rod ends unless they are protected with a rubber boot otherwise they will chew out and create a knocking noise.