Tech Tip #7: Rear Suspension Disassembly
Rebuilding the rear suspension on a 1983 308 QV Ferrari
(Identical to GT/4, GTB, GTS, GTSi, GTBi, QV models and 328 series to chassis #76625. Not for the Mondial)
Done during the winter of 2000-2001. Written by "Enzo", edited by Carl Jones (CJ's notes are in italic)
308 Quattrovalvole, 328 GTB & 328 GTS Workshop Manual. You may also use the 308GT4 workshop manual, the Mondial workshop manual and the 308QV/328 workshop supplement manual to get at the right information. The 308 parts manuals are also helpful as they show a blow-up of the dismantled suspension.
For the manuals also check Steve Jenkins' site at http://ferrari.stevejenkins.com/books/
Suspend the rear of the car on two jack stands (make sure that you chock the front wheels!) and start removing everything in sight.(! well almost - CJ). I chose to suspend the car on the chassis rails close to the suspension. Place the jacks so that hey do not restrict access to the suspension bolts. I assume that an electric lifter that does not lift the wheels can also be used.
Begin disassembly with
1) the wheels,
2) fiberglass covers,
3) brake lines,
4) handbrake cables,
5) anti-roll bar,
6) coil spring and shock (there is no need for a spring compressor, the coil and the shock come off as a single unit, but be prepared to suspend the hub assembly as it will sag),
6) the outer half – shaft boot and bearing assembly (see below for details) and
7) the wishbones.
Have something handy to plug the brake lines as they will leak once disconnected.
Note that the lower A-arms (or wishbones) are removed by loosening the bolts within the chassis rails and not from the two bolts that are visible from within the wheel well. I.e. you'll have to crawl underneath the engine. (Or you can slacken the wishbone "U" supports and move them out a cm or so then undo them from the wishbone side - CJ)
I chose to use new nuts and bolts everywhere from superformance. If you decide differently remember to label while removing!
When removing the lower wishbones you'll come across the camber and toe adjustment shims. They are right next to the chassis rails and are squeezed in by the "U" supports of the lower wishbone. You can disassemble them, as the suspension will need a total adjustment once you are finished, but I suggest that you measure their thickness so that you have a guideline for re-assembly. (I have seen cars incorrectly set up out of the factory so make sure your alignment is done by a competent shop that can align all 4 wheels - CJ)
(Note that if you plan on removing the hubs for either bearing or caliper maintenance you can remove them with the wishbones, otherwise you can leave the hubs and half shafts in place. However, you must support the hubs on a stand. Never let then hang, loading the CV joints and especially never support them by the brake lines. Note that the hubs will tend to fall towards the caliper if you decide to leave the attached to the half shafts - CJ)
These photos show the state of the suspension before I touched anything and yes the work was done in the open !
1.3. Half-shaft disassembly (See above, but only if you want to do the bearings- CJ)
Remove the 6+6 bolts and castle nuts from the half-shaft. This is a lot harder than it sounds. On my car the castle locking nuts would not budge, period... It seems that exhaust heat and rust freezes the nuts, anyway they were totally stuck solid …
In the end, hard, sharp hits with a hammer and chisel split the bolts. Alternatively, snap-on, make a bolt splitting tool that should fit. Other bolt splitting tools will NOT work as they need to wrap around the bolt and the flange of the hub prevents this. In the photo you can see the Allen side of the bolts and the bearing before and after disassembly. Once the universal joint is split, have some old towels to wipe the grease with (Yes, but make sure you replace the grease with some molybdium dIsulphide grease, the QV manual states MOLYCOTE BR2 - CJ ) and then wrap the joint with a plastic bag and rubber bands so that any remaining grease will be contained. You should not need to remove the rubber boot clips.
1.4. Bushings removal
I had a hell of a time with this. Both inner and outer bushes had excessive rust on mine and were really jammed solid. The car had been kept in the UK for about 9 years and even though well cared for, this is what wet weather, salt spray etc can do. Most of the rubber was crumbling away as well. The chrome bearings inside the outer bushings were again worn away with the chrome having flaked mostly off. Note that the inner bushings have two spot welds that have to be ground off. I used a Dremel mini drill, which worked fine. Be careful to totally remove the welds even so far as to grind down the bushing because as the bushing will be pushed out of the wishbone, any remaining weld material will tend to scrape away at the bushing seating area, which is not good…
After a lot of experiments, the best approach for removing the bushings (inner and outer) seemed to be:
1. Make a jig from a steel tube to support the A-arms. Apparently a (Well that's nice, I bashed mine out with a hammer! - CJ) socket from a wrench set will also do nicely but I had one made especially at a machine shop. An easy job on a lathe apparently from any machining shop. Check the photo, it is simply a hollowed cylinder that will support the wishbone while allowing the bushing to slide out inside the cylinder.
2. Spray the bushings with WD-40 or similar and let soak through.
3. Press the bushings out using a nut and a bolt as a specialized vice. Check photo. Use at least 10mm bolt thickness as the pressure is such that it will either break or the threads will strip. Be prepared to use a lot of force. The squeaks and groans were horrendous….
2. Replacement bushings
Get a totally new set of inner and outer bushings. Do not neglect the outer ones. I got mine from Mike Elliott at www.superformance.co.uk , and I can thoroughly recommend them for their expertise and pricing. Apparently they also supply Ferrari with parts. Superformance recommend that you use the same type for front and rear even though the workshop manuals say otherwise. Superformance will also sell you different bushing hardness if you are so inclined.
3. Shocks and springs
Apparently the KONI shock absorbers can be rebuilt and even modified to have adjustable ride height. I personally chose simply to buy new ones.
The springs were sand blasted and powder coated professionally. The reason was that I found it impossible to do the job manually. I also got new bushes for the shocks from superformance as the old ones were really messed up. I neglected however to get a set of rubber pads for the springs, this is where the springs attach to the shocks.
I had the disassembly and assembly done professionally as apparently you can easily kill yourself if one of those springs come loose.
Another niggle is that as you can see if you watch the photo carefully enough is that the spring is not 100% straight. Apparently and according to CJ this is no big deal and most 308 springs are like this and won't get worse. Anyway replacements are not expensive. Also remember to measure the spring length before assembly so that you can verify that the springs are in a good state.
Enjoy photos of the coils and shocks before and after. (!)
4. A-arm (wishbone) cleaning
After the bushings were removed I had the A-arms sand blasted while covering the seating are (SP Area) of the bushes with plastic putty (children's version of). The bushing seating areas were cleaned superficially with sand paper and painted with a simple anti-rust primer as were the bushings in the spots where they would be seated on the wishbones.
In the photos are the wishbones before and after sandblasting. After sandblasting, go to the next stages quickly as the wishbones are made of mild steel and will pick up rust immediately.
5. Bushings Insertion
Again as for removal I had a special cylinder made to press the bushings in with the bolt and nut vice (see photo).
Note that you'll need two drilled aluminum plates to serve as guides and platforms for the nut and bolt vice. Also note that you'll need to drill a small hole in the case of the inner side of the outer bushings (Not really, the dowel pin is removable with a pair of pliers. Note it's really important to make sure the bearing surface is not damaged during insertion so use the old Teflon washer as a sacrificial surface - CJ) so as not to crush the small dowel pin that will hold the Teflon coated washer in place. It'll be obvious when you try and do it. Make sure that the aluminum (or other material) plates remain parallel during the whole insertion process as the forces are quite high and the bushing may go in crooked.
The inner bushings were then argon welded. (It is absolutely necessary to have the bushes sit absolutely flush with the wishbone. Any gap will allow axial movement of the bush within the wishbone and eventually the locating welds will crack and the bush may damage the wishbone to the point where the wishbone fails. I have seen this happen - CJ) I took special care to make sure that the bushings did not move and that the welding was done quickly so as to minimize any damage to the rubber. I placed 3 welds per bushing compare to the original two. (see photo)
Apparently that is not too important as the welds are only there to prevent rotation of the inner bushing in relation to the wishbone.
Note that the insertion force was in my case – much smaller than the force used in the extraction.
In addition, when inserting the outer Teflon bushes I suggest that you remove the inner Teflon coated bearing and then wrap the bolt used as a vice in paper tape as to prevent damage to the Teflon coating. Once the main body of the bushing is in then you can insert the inner one. The pressures were such that the inner Teflon coated bearing (I installed the Teflon lined bushes in the larger bush before installation - CJ) was harder to insert after the outer bushing was pressed in the wishbone as apparently the whole outer bushing was being squeezed – slightly radially, but enough to change the tolerances. Impressive!
As I mentioned I had primed with anti rust paint the seating areas of the bushings and the bushings before insertion. The inserted bushings were then wrapped carefully in paper tape to prevent paint from reaching the Teflon bearings. 4 coats of satin finish Hammerite, painted in 6-8 hour intervals and finally given a coat of hammerite spray paint. The results as per the photos including assistant... In addition and as a final touch up the visible seating areas of the wishbones and the bushings were given a spray of elasticized paint to prevent water ingress.
6.1 Powder coating
Alternatively you may want to powder coat the wishbones. I had heard a number of opinions on this and no clear winner. According to CJ at least, the wishbones will flex during driving and he has seen powder coating flake off, so it's really up to you to choose
8. Anti-roll bar
9. Re-assembly: to be continued soon...