1998 LS400 Front suspension rebuild

Razor61 · May 28, 2022

The planned front suspension rebuild has begun…………I’ll update as much as I can as I progress.

Undertrays removed, jacked up, secured on 4 axle stands and wheels removed . Took a couple of hours all in.

Howplum · May 28, 2022

I'm looking forward to following your progress because I hope to do mine sometime. Good luck.

Malc · May 28, 2022

I've never had the undertray fitted to mine since I bought her some 11 years ago .... my previous 2 x Ls400s had the Undertray ok tho' ...... not sure it's absence is too much of a deficit ........... makes for a slightly lighter load and improved mpg by a nats whisker no doubt

Malc

Razor61 · May 28, 2022

Everything dismantled and removed apart from the RH strut bar, bolt is seized as expected so will cut through the bolt tomorrow. 100% had enough for today and no energy left to spend a couple of hours sawing through the strut bar bolt in 2 places, it’s a PITA job so will start fresh tomorrow.

Razor61 · May 28, 2022

7 hours ago, Howplum said:

I'm looking forward to following your progress because I hope to do mine sometime. Good luck.

Thanks, should be straight forward from now on. All of the new bits I’ve painted ready to fit, some bits I’ve taken off need fettling and painted which will take a day or 2 for removing rust and painting.
Its a decent sized job but will be worth all the work, 🙏

Howplum · May 28, 2022

Paul, are you using a mixture of new Lexus/aftermarket components and/or re-bushing the originals? Did you consider polyurethane bushes? Will you be replacing the nuts and bolts?

Razor61 · May 28, 2022

45 minutes ago, Howplum said:

Paul, are you using a mixture of new Lexus/aftermarket components and/or re-bushing the originals? Did you consider polyurethane bushes? Will you be replacing the nuts and bolts?

Howard, all Lexus OEM parts are being used and mostly new OEM nuts/bolts/washers and bought from Amayama mostly. The front strut bars have new OEM Lexus bushes pressed in. They are the only bits that have had replacement bushes rather that a complete new suspension arm. I did consider PSB bushes for the strut arms on the last LS400 MK3 I had and bought a set which I still have, this was because the original bushes were not available but I fitted a pair of Toyota Century bushes instead. Other than that I didn’t consider poly bushes.
The same applies for the rear suspension when I do it, I even have new Toyota/Lexus OEM ‘rear carried sub assy’ for both sides and the new bearings to go with them - very expensive parts, I was quoted £1600 from Lexus for replacing one of them because one of the bushes had some play.

Razor61 · May 30, 2022

Front strut bar camber bolt removed this morning, I had to use a 9inch grinder without the guards to do the job. You can get in, grind through the sleeve and bolt without damaging anything if careful and with the strut arm pushed up as far as possible to give the best access. I had to buy the grinder and metal cutting discs, £55 for a MacCallister with 5 discs. Well worth the money, 20 mins and it was off rather than hours of effort with a hack saw blade.
Plan for today is clean and paint the strut brackets, rebuild the shock/struts ready to fit. Paint the inside of the strut turrets and everything should be ready re assemble. Either today or tomorrow for the reassembly, raining at the moment so will probably depend on the weather…………

BigBoomer · May 30, 2022

On 5/28/2022 at 9:54 AM, Malc said:

I've never had the undertray fitted to mine since I bought her some 11 years ago .... my previous 2 x Ls400s had the Undertray ok tho' ...... not sure it's absence is too much of a deficit ........... makes for a slightly lighter load and improved mpg by a nats whisker no doubt

It will probably slightly reduce Mpg due to increased aerodynamic drag.
The undertrays are there for to smooth airflow and reduce noise.

Razor61 · May 31, 2022

Rebuild complete, been for a test drive and it drives like I imagined a new LS400 should drive. It’s been a hard slog for 3 days (had Sunday off) but worth all the effort to go over a speed bump and the annoying noises have gone………
I had all good intentions of taking pictures at various stages but it never happened.

Some bits I replaced didn’t need replacing and were 100% ok from what I could see with no sign of wear at all, other bits did need replacing.

Lower controls arms - looked perfectly good to me with no sign of cracking in the bushes.
Strut bushes - knackered and split - I’ll be refurbing the strut arms I removed and fitting new OEM bushes to either keep or flog.
Shock absorbers - 1 was reasonable - the other was knackered
Top mounts - looked perfectly good to me
Isolators - perfectly good apart from a small split in one of them ( I may have done this with the spring compressors)
Bump stops - like new
UCA’s - not sure about these - bushes looked ok to me - ball joints didn’t have any obvious play
Drop links - probably knackered but definitely were knackered after I cut through the shaft on them with the grinder. Only way to get going with dismantling it all without spending hours trying to remove them properly.

Next few days I’ll be replacing the rear engine mount and the steering rack bushes then fitting all the under-trays and covers.

Howplum · May 31, 2022

Well done. I read somewhere that the steering rack bushes can be quite tricky, so I'll be interested to hear how you get on.

Are you going to be rebuilding the rear suspension as well?

Razor61 · May 31, 2022

37 minutes ago, Howplum said:

Well done. I read somewhere that the steering rack bushes can be quite tricky, so I'll be interested to hear how you get on.

Are you going to be rebuilding the rear suspension as well?

Cheers, yes I will be doing the rear as well and have all the bits. When this will happen I don’t know, I could probably do it all by Sunday but my body wouldn’t cope with it after doing the front - everything aches at the moment, especially my back…….

I’m doing the steering rack bushes while all the under trays are off, I’ll have a good look first though and see what the situation is. My body will cope with this I think🙃

Razor61 · June 2, 2022

On 5/31/2022 at 8:36 PM, Howplum said:

I read somewhere that the steering rack bushes can be quite tricky, so I'll be interested to hear how you get on.

Had a good look at it and it does look a tricky job, I would say a proper PITA job without the car being on a ramp. Even on a ramp it won’t be easy.

I replaced the rear engine mount/transmission mount, it wasn’t as easy as I thought but it’s done now.

Razor61 · June 6, 2022

Done a fair few miles since the rebuild and it drives much better, a bitter jiggly and wanders a little bit because the alignment needs doing. Car is booked into Lexus Bolton for Saturday to get the alignment done so should be spot on after.
As said previously some of the bits I replaced looked in good shape but others were knackered. I can't say what in particular was causing the noises over speed bumps and potholes etc because I replaced everything (bottom ball joints I did a month or so ago). However, I would guess that the shocks, strut bushes and maybe the UCA's were the main things that were causing it all. I suspect for my car at 90k miles, replacing the shocks, front strut bar bushes, drop links and arb bushes would have gone a long way to sorting it all out or sorted everything.

For the old shocks - on one of them when you pushed the push rod right in, it just stayed there and didn't move back much at all so that was knackered. On the other, the push rod did come out very slowly but not as it should so that wasn't good.
Front strut bar bushes - they were split all the way round and putting a bar in the centre and flexing the bush showed how bad they were.
Drop links - just cut them off so they could have been worn or not. Didn't feel knackered to be honest.
UCA's - bushes looked ok, difficult to tell if there was any play in the ball joint, I couldn't feel any so I would guess they are are just fine.
Lower arms - bushes looked ok to me after couldn't see any cracking in the rubber when flexing them with a bar. Rest of the arm was sound as you would expect.
Springs - looked good with very little rust so didn't paint them. I had to use 4 x spring compressors to compress them enough to get the top nut on. New isolators didn't help because the rubber wasn't compressed but managed it and lined them up ok. Applying some fairy liquid to the top/bottom of the isolators helped when moving/twisting them to align one of the top mounting bolts with the bottom shock mount correctly.
Top mounts - looked fine to me.

On another very slight issue I had, when sat at traffic lights in neutral I could detect some jiggling/vibration coming through the bottom of the seat. Very minor but it was there nonetheless, after replacing the rear engine/transmission mount it seems to have gone now. I only replaced the mount because I had a new one. Comparing the old mount to the new mount showed the old mount had compressed by 10mm. Maybe that was enough to cause the vibration I felt.

Howplum · June 6, 2022

Experience has taught me that low mileage, whilst desirable to a degree, doesn't necessarily mean that components, such as rubber, plastic, steel and electronics, are proportionately less liable to deterioration that higher mileage cars.

Perhaps your exercise also proves that whilst the MoT test might deem the car to be roadworthy and safe, it doesn't necessarily mean it is operating correctly or efficiently.

Razor61 · June 6, 2022

39 minutes ago, Howplum said:

Perhaps your exercise also proves that whilst the MoT test might deem the car to be roadworthy and safe, it doesn't necessarily mean it is operating correctly or efficiently.

Absolutely, my Dad's 2004 Mercedes C230K auto is a case in point. A few years ago I drove the car back from Liverpool to where I live in Lancashire. While stopped at traffic lights in 'Drive' I took my foot off the brake and then back on again, there was a loud clunk like the front calipers were loose or something. I did this a few times to make sure I wasn't imagining it. When we got back to my house I jacked the car up, removed the wheels to have a look. One of the bottom ball joints was knackered and using a pry bar you could see the movement and it was quite a lot.
I said "Dad, this ball joint is totally knackered!!" to which my Dad replied "that's funny it was only MOT'd last week"
The ball joint was so bad it should have failed the MOT in my opinion, I think his local garage cuts him a bit of slack and isn't too picky but it shouldn't really be done.

Malc · June 6, 2022

2 hours ago, Razor61 said:

UCA's - bushes looked ok, difficult to tell if there was any play in the ball joint, I couldn't feel any so I would guess they are are just fine.

when my first one " went " all I heard was a resounding clunk when i was up in the Italian Dolomites driving around ....... I obviously stopped and looked and couldn't find anything at all so thought maybe i had hit summat which I couldn't find ........... months later the car went in for it's MOT and it failed on that UCA alone .... but no clear evidence really of anything wrong ...... it just failed the " bar " test I'm thinking for the MOT ......... she drove impeccably as usual the whole time whatever was wrong with that UCA

Malc

Razor61 · June 7, 2022

Just one piece of information to mention is the torque settings for the camber bolts.
Front Strut Bar camber bolts - 181nm
Lower Suspension Arm camber bolts - 251nm
I have 2 x torque wrenches, smaller range up to 25nm and a medium range (can't remember the range but it doesn't go up to 180nm never mind 251nm)
I had to buy a bigger torque wrench for the camber bolts, 'TengTools 1292AG-E4 1/2" Drive Torque Wrench 350Nm' and it's a beast.................

Razor61 · June 26, 2022

This has progressed quickly to rebuilding the rear suspension as well due to seized rear camber bolts, documented in another general topic for the car.
Didn’t replace the shocks and rear UCA’s but replaced everything else.
After a full alignment and a few hundred miles driving, the car is driving better, suspension is tighter with no annoying untoward noises, slight wandering has gone and tracks spot on.
I did notice a slight suspension noise on the drivers front so jacked up the car this morning and checked all the nuts and bolts on the front. The rear bolts on the front UCA’s were tight but the fronts were not as tight as they should be, not loose by any means but I could move 2 of the bolts reasonably easily with a 14mm combination ring key, so tightened them up. Maybe I missed tightening them, possible cos I did so much at the time. I couldn’t get the torque wrench on them with the springs in place so had to judge the torque of 116nm (pretty sure it’s that).
Used a medium 3/8 breaker bar with a shallow socket on 2 of them with a bit of pipe over the end. The others needed a 14mm ring key, big ring key and a big adjustable all in line to give me enough torque.
Went for a drive and listened out for the ‘noise’ and it seems to have gone now.
I’ll check them again when I do an oil change, with all new stuff fitted it’s a good idea to recheck the torque after a bit of driving and everything has settled down.

PaddyT · November 15

Hijacking this post to see if anyone might have the knowledge/experience I need to diagnose an issue I've started to experience. Only had my LS400 for 3 weeks but I've already had over 2,000 miles in it! Took a dent to the wallet in fuel but smiles all around. However, I have noticed that the car seems to wander slightly even at low speeds. I've had the car jacked up and looked for play in all 4 weeks 12-6, 9-3 position trying to move it and nothing obvious. I have noticed though that I seem to have a bit of play in the steering, I would say 1-2degree of steering where nothing happens at the wheels which I'm suspecting is my issue. Only seems to be when the wheel is in the centre position leading me to believe it's wear in the pinion/rack gear itself? I've confirmed no play in the actual steering column at least from the steering until the column enters the floor near the pedals.

I've had the car 4 wheel aligned using a hunter system. It was spot on after this for about a week. Anyone experiences anything similar? I suspect the car is mostly original in terms of suspension as it's relatively low milage at 90k.

Malc1 · November 16

I don’t think I’ve experienced any discernible “ wander “ in any of my Ls400s …….. if I had I’d have suspected tyre pressure issues ……. and that’s over some qtr million miles or more Ls400 amazing driving 😄

Hope you discover it ok …… must be so frustrating not knowing

Malc

Razor61 · November 16

My guess would be front strut bar bushes or the rear bushes.
Front strut bar bushes can be checked by braking sharply/stamping on the brakes, you’ll get a clunk if they are gone. You will know what I mean when/if you feel it. These bushes ‘will’ go bad, split.
You had the alignment done and it was ok for a week, not likely to be the rack then. If the strut bushes are gone and are moving position then the alignment will go out again.