Premature flex disc failure?

[BenzBoy]

I've finally managed to get underneath the BMW e36 to see what the cause of the propshaft thumping and vibration is. I'd ruled out the flex disc as I put a brand new one on 12 months ago (about 6k miles) when I did the engine and trans swap. My suspicions were with the centre bearing carrier or perhaps the diff front mount bush. When I removed the propshaft, I noticed there were big cracks in the flex disc and the cords were beginning to splay out of the sides. It was also really soft.
The centre bearing carrier looks and feels fine, as do the diff mount bushes, so I'm guessing the flex disc is the sole cause.

When I did the engine and gearbox conversion I used the front prop from the donor and the rear from the original car. I had to do this as the original auto prop was too short. I didn't give much thought to balancing the prop to be honest, I just slid the two together and took it for a drive - no vibrations, so I figured it was all fine. Something I read on another forum was the possibility of the prop being slightly out of balance and killing the flex disc, but to my mind either the prop is vibrating and out of balance, or it isn't and everything is fine. Am I over-simplifying things?

I'm planning to get another flex disc, but this time a genuine BMW one or at least OEM-spec one. I used a cheap Q-Drive one from Euro Car Parts last time. I'm also renewing the centre support bearing as apparently you're meant to change that at the same time, and the prop is off so I might as well.

One small admission: I did go drag racing with the car last month, which I think might have finished the flex disc, but surely that part should be able to stand up to a few clutch dumps at 4k rpm?! Right guys?! The car behaved fine after that but the problem emerged about a week later.

Did I just buy a curse word part, or is there something else going on here? Anyone else had any experiences of flex discs failing after 6000 miles?

[shampooefficient]

I'd be looking at cheap part failure, I must say I've never heard of Q-drive.

[ChasR]

I'd say it's cheap part failure. I've had a few Q-Drive items fail on me, drop links being the big one. The most laughable one was an engine mount failing in the 205 within a year and 10,000 miles of it being fitted. The other mounts were not in terrible condition either.

The rotoflex joints in the Lotus and Imp world have been known for being made of chocolate as well these days.

[colnerov]

Nov 15, 2015 20:52:42 GMT ChasR said:

The rotoflex joints in the Lotus and Imp world have been known for being made of chocolate as well these days.

They were not particularly long lived back in the day either.

Colin

[BenzBoy]

Thanks for the replies, there is quite a wide range of prices for these parts. GSF want about £70 for theirs, and Euro are about £25. No idea what BMW charge, I suppose I'll find out tomorrow. Could do with finding a few more sources for parts though.

[BenzBoy]

After a bit of searching it turns out Q-Drive flex discs have a bit of a reputation for failing. I think it's Eurocarparts own brand and I've seen a fair few negative comments about the quality of various Q-Drive branded parts.

I'll try and source a Febi, Lemforder or genuine BMW component tomorrow, and hope I don't destroy it within a year!

[ChasR]

Out of that list I'd go for Febi or genuine BMW TBH. I've had a Lemforder arm fail from ECP within a year, albeit on a car with a reputation for them failing (Alfa 147). The original item lasted 70k however...

Someone did tell me that ECP bought part of the Lemforder name to use as well, as they have with Pagid. OTOH the Lemforder but genuine rear ARB links from Ford are still fine on the back of my dad's car 80k later (we changed them at 220k).

[Anthony]

Nov 15, 2015 23:51:53 GMT ChasR said:

Out of that list I'd go for Febi or genuine BMW TBH. I've had a Lemforder arm fail from ECP within a year, albeit on a car with a reputation for them failing (Alfa 147). The original item lasted 70k however...

Someone did tell me that ECP bought part of the Lemforder name to use as well, as they have with Pagid.

That's a little worrying, as Lemforder are one of the only brands of suspension/steering parts that I have any faith in actually lasting and will happily pay the premium because of that.

Many of Q-Drive's offering are nothing short of junk frankly and I won't fit them to anything regardless of price, because I know that inevitably I'll only end up having to do the job a 2nd time to replace them in the near future. GSF's V-Tech brand is much the same - indeed, I suspect anything unbranded or with a brand you don't recognise is probably going to be extremely dubious these days.

[welshpug]

try allgermanparts, they do a few different brands, trw, lemforder, meyle, febi and are mainly a bmw / vw group specialist.

I had a donut fail on my e34 tds, needed to fix it quickly so took the one from the manual box I have for it in the shed, looked like a genuine bmw item and its still there 20 k miles on

I think the original was 80k miles old, but got killed off by an auto box that thuds into gear every now and then, oh and a bit of towing

[ChasR]

Nov 16, 2015 8:16:57 GMT Anthony said:

Nov 15, 2015 23:51:53 GMT ChasR said:

Out of that list I'd go for Febi or genuine BMW TBH. I've had a Lemforder arm fail from ECP within a year, albeit on a car with a reputation for them failing (Alfa 147). The original item lasted 70k however...

Someone did tell me that ECP bought part of the Lemforder name to use as well, as they have with Pagid.

That's a little worrying, as Lemforder are one of the only brands of suspension/steering parts that I have any faith in actually lasting and will happily pay the premium because of that.

Many of Q-Drive's offering are nothing short of junk frankly and I won't fit them to anything regardless of price, because I know that inevitably I'll only end up having to do the job a 2nd time to replace them in the near future. GSF's V-Tech brand is much the same - indeed, I suspect anything unbranded or with a brand you don't recognise is probably going to be extremely dubious these days.

To be fair to Lemforder the genuine Ford ARB drop links my dad got for his Mondeo lasted ages (80k later they are still on the car). I know from experience that despite Ford and ECP selling Sachs dampers (or Boge as well) they always last longer from Ford. ECP only spec 2 Dampers for all Mondeos, regardless of what it is - 1.8 boggo spec to a full fat ST200/ST TDCi. Non ST cars (regardless of engine) have one spring and damper available whereas the STs have another damper, which ironically costs the same as it does from Ford. Ford sell around 6 dampers for a Mondeo, depending the spec and wheel size the car came with. The Boge items on my dad's Mondeo lasted 20k before they were soggy (and IMO not much better than the 200k items that came off!), the genuine items on our V6 Auto (the heaviest combo for a Mondeo bar it being a derv) did over twice that before starting to have the performance ebb away, and even then it wasn't that horrific. I wish I could have said the same about the Bilstein B4s on the rear of that car which were fitted a good 40k later.

In a nutshell, I don't doubt the parts but I do reckon the motor factors do try to save costs wherever they can and do something that will last the warranty period. They are a business after all. From a business perspective it is easier to buy 1 part to fit 4 cars as opposed to 4 parts for the 4 cars. That is not to say that the quality of the parts are necessarily bad, but it is becoming trickier to tell.

[omega]

warning
stupid question alert

whats a flex disc?

[welshpug]

rubber donut thing that is bolted to the tripod on the output of the gearbox with three bolts, the propshaft also has a tripod on its front end which also bolts to said donut with three separate bolts.

the propshaft has a spigot on its nose, so all the donut does is transmit the rotational output from the gearbox whilst damping driveline shunts and vibrations.

[bortaf]

Nov 16, 2015 21:19:59 GMT omega said:

warning
stupid question alert

whats a flex disc?

The rubber doughnut on the prop just after the box, as with wipers there is good rubber and bad rubber, the cheap stuff drys out and cracks or goes soft and disintegrates, used to have the same problem on cortinas years ago, allways used good S/H rather than cheap aftermarket where possable.

[omega]

thanks

[BenzBoy]

Often also called a giubo (or misspelled guibo), or propshaft coupling.

I've ordered a Febi one which is twice the price of the Q-drive one. "Buy cheap pay twice" I think is the moral of this story, but to be quite honest I didn't think that there was such a huge difference in quality on these parts. I learned a lesson there!

[omega]

I just thought they were called rubber doughnuts!
had a imp as my first car and managed to break one,got towed back with the shaft flapping about!! had no money so went to the scrapyard and got one of another imp but couldn't get it to fit was to big.later found out that when new they where compressed with a big jubilee clip.but while under the car found that the shaft had ripped out the fuel line and handbreak cable.well being young and knowing nothing about cars sold it as a non runner for 20 pounds!
sorry PUX671H wonder if it is still alive.

[theheap]

Q-Drive is rubbish. Never lasting parts

[Stu]

Just wanted to add that the genuine or good make aftermarket donuts can take a hammering and don't fail. My brother in law races an E36 Compact with 6 cyl 250bhp ish engine and manages to break all kinds of transmission bits, expensive racing clutches etc. but the old OEM donut just keeps on trucking!

[carat 3.6]

Just a thought, your propshaft and gearbox are both level to each other? If they aren't it will kill any flexdisc quickly.

[BenzBoy]

Nov 21, 2015 20:48:56 GMT carat 3.6 said:

Just a thought, your propshaft and gearbox are both level to each other? If they aren't it will kill any flexdisc quickly.

I think so... the engine and box were installed using the original BMW mounts and brackets, and the mounts look to be in good shape.

I've fitted the Febi flex disc, making sure it's installed the right way around, and a new propshaft centre bearing and carrier. The vibration and thumping has gone so I'm happy! Here's what happened to the Q-Drive part:



Hope the new one lasts longer!