Tdi75 rear springs and shocks - HELP!

Pinkythelabrat

A2OC Donor
Here we go. This shows the problem a bit more clearly.




Pretty laden but as well spread as possible. Me and about 100kg of books up front. Maybe another 150kg in the back. Spread as far forward as possible.

The rear suspension is completely compressed and pretty much touching the arches and scrubbing on level ground.

The front is only a little compressed.

This is wrong right? It feels like the rear springs are too weak and compress too easily but they are supposed to be OEM spec!


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Pinkythelabrat

A2OC Donor
Hi @A2Steve. They are about 12 months old.

I ordered them in March last year but I’m sure it was September or October when I fitted them.

You know what I’m like...


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Pinkythelabrat

A2OC Donor
I worked out the loading accurately.

The car, as pictured earlier, had approximately:
77kg in the front seat
176kg in the back seat
110kg in the boot.
It was actually pushed forward a bit more but I had the seats down.

So one adult in the front, two in the back and a fairly heavy suitcase (BA) of 25kg for each adult.

When driving I can add another 80kg in the front.

I should be able to carry four people plus 25kg each without the car using its tyres to hold the arches off of the ground? That’s not an unreasonable load is it?


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Andrew

A2OC Donor
I worked out the loading accurately.

The car, as pictured earlier, had approximately:
77kg in the front seat
176kg in the back seat
110kg in the boot.
It was actually pushed forward a bit more but I had the seats down.

So one adult in the front, two in the back and a fairly heavy suitcase (BA) of 25kg for each adult.

When driving I can add another 80kg in the front.

I should be able to carry four people plus 25kg each without the car using its tyres to hold the arches off of the ground? That’s not an unreasonable load is it?


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I am looking at the handbook(2004) on the the 1.4TDI stats page.

Gross Vehicle Weight = 1535 kg
Kerb Weight (unladen weight) =1095 kg

Difference = 440 kg, I assume is load.

Your scenario, assuming 75 kg per person, + luggage

4 X 75 + 4 X 25 = 400 kg

Yes, you seem just under by 40 kg.

However what I don't understand is how the manual can quote a blanket figure without allowing for build, leather seats, Webasto, spare wheel or not, difference fuel capacity, headlight washer spec must add a lot weight when water tank full, etc

More research needed, maybe the individual figure for a car is on the options sticker.

Andy
 
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Pinkythelabrat

A2OC Donor
If the manual is quoting that - and thank you very much for looking in to the details; very Awesome of you - then the car should be drivable carrying 400kg.

5mph was like someone had stuck a card in the spokes of my bike and any bump probably took 1000 miles off of the life of the tyres.

Not even close to driveable on a flat surface.


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audifan

A2OC Donor
If you want to carry those loads regularly then perhaps airbag suspension would be required. Standard setup is designed for those loads so your springs have either the wrong thickness, wrong number of turns or the wrong rate.
 

Howey

Member
Mine was low at the rear, the old springs (which going by paperwork had done 43k and 6 years fitted at a vw specialist) upon removal were a good few inches shorter than the kyb replacements, had the old ones sagged or were they incorrect for the car from the word go, i simply dont know??? Would still like to fit oss ones to see if the stance is a little more level but bit of an expense just to pander to my curiosity!
My car would catch on those silly 3 in a row speed bumps slightly somewhere, but never the wheels on body, running 175/65/15
 

Pinkythelabrat

A2OC Donor
I had a lengthy chat with AUTODOC today. It wasn’t massively enlightening.

The site part finder suggests the Monroe SP3249 for both OEN versions of the TDi75. My understanding is that this is for the OSS car so should be capable of carrying more weight. This is the one I bought and fitted previously.

The Bilstein B3 36-147717 should be the equivalent OSS spring.

The AUTODOC technical team checked my VIN and suggested the Monroe SP3435 or Bilstein B3 36147700 as the correct parts.

The details for these are wrong on their site (length 7.9mm???) but it appears that these are the non-OSS springs so pretty similar but presumably less load capacity.

The VERY helpful man suggested that my issue with the very poor load capacity was perhaps something else other than the spring and I should get a mechanic to check my car!!! What else could it be???? It’s car, rubber, spring, rubber, car, rubber, road! There’s not much else involved!

I’m not delighted and am now unsure what to do. If I go for the recommended part surely this will REDUCE my load carrying capacity!

Or do I assume the springs were incorrectly labelled/defective and trust that replacements will solve the issue?




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Pinkythelabrat

A2OC Donor
Okay. I’ve calmed a bit and decided.

Mike Skipton runs the same alloys as me on Tank and has larger tyres (205/55 R16) and HE mentions buying the B3 147700 springs - so if it’s good enough for Mike Skipton...

He also mentioned in a chat I found that the 147700 were the ‘reinforced’ spring and the 147717 was the ‘normal’ spring. That seems the opposite to what I found but I expect he’s smarter than I am!

They are also a bit cheaper...


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cheechy

A2OC Donor
I've been thinking about addressing the same question here too. I fitted Monroe sport shocks and weitec springs at 30/30mm lower (was meant to have been 25/30 but I dont think so) but I'm finding that any moderate load seems to point the front of the car upwards so may have to go for standard sport springs - maybe OSS rated - at the back but not clear at all around what that will do to the ride.

Car handles well right now but last thing I want is the car starting to wallow round corners again
 

Pinkythelabrat

A2OC Donor
Ill let you know how I get on in 3 months when I get around to fitting these Bilstein springs

I wanted the OSS springs because I carry a spare and also didn’t like that the tyres rubbed with moderate loads on bumpy roads (I take shopping to my parents in the highlands every few months - very bumpy roads and A LOT of food weight - mostly beer!).

It seems to be deliberately confusing. I know Robin Cox did a definitive guide (but I can’t find it), the details for the Monroe springs are wrongly listed and the Bilsteins seem to want to be mysterious about factors like length, number of coils etc.

Maybe mechanics don’t like DIYers for some reason?

My hat is off to anyone who tries anything new like deliberate lowering or sporty handling. I can’t even get the basics right!


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cheechy

A2OC Donor
Ill let you know how I get on in 3 months when I get around to fitting these Bilstein springs

I wanted the OSS springs because I carry a spare and also didn’t like that the tyres rubbed with moderate loads on bumpy roads (I take shopping to my parents in the highlands every few months - very bumpy roads and A LOT of food weight - mostly beer!).

It seems to be deliberately confusing. I know Robin Cox did a definitive guide (but I can’t find it), the details for the Monroe springs are wrongly listed and the Bilsteins seem to want to be mysterious about factors like length, number of coils etc.

Maybe mechanics don’t like DIYers for some reason?

My hat is off to anyone who tries anything new like deliberate lowering or sporty handling. I can’t even get the basics right!


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Rear ARB makes a notable difference - just saying :D
 

BigBang

Member
Well have you considered that you have way bigger tires than it should be? From the picture above, you are running 205/50R16 but correct tire size is 185/50 or 195/45 R16. Thats the main reason why it rubs wheel arches. Your current tires have 20 mm bigger diameter compared to 185s. Complete load with you onboard is 440 kg which is totaly on the weight limit of the car...
 

Pinkythelabrat

A2OC Donor
Hi @BiggDogg.

I was previously running 205/55 so this was a step down and was the size recommended by a lot of people on here using the Ronal alloys with no complaint about scrubbing.

I think I calculated it as only a 10mm increase in tyre rubber over the tallest ‘standard’ A2 alloy/tyre combo but I am prepared to be proven wrong.

The issue isn’t so much just the scrubbing. With the 400kg I’m sure it would be scrubbing on a tyre 20mm smaller as well! The car is sitting about three inches lower at the back with a load versus no load! The front barely drops.

This morning I carried about 80kg(me) plus 250kg of building materials. Almost all placed in the rear seat area (18kg concrete blocks so pretty dense) and the car was still barely movable without kissing the arches.

I’ve ordered new springs so we’ll see


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audifan

A2OC Donor
Have you tried a local parts factors? Quote you registation number to them and their system will come up with the standard springs for your car. Order them and if the car sits too low take them back.
 

damadgeruk

A2OC Donor
Hi @BiggDogg.

I was previously running 205/55 so this was a step down and was the size recommended by a lot of people on here using the Ronal alloys with no complaint about scrubbing.

I think I calculated it as only a 10mm increase in tyre rubber over the tallest ‘standard’ A2 alloy/tyre combo but I am prepared to be proven wrong.

The issue isn’t so much just the scrubbing. With the 400kg I’m sure it would be scrubbing on a tyre 20mm smaller as well! The car is sitting about three inches lower at the back with a load versus no load! The front barely drops.

This morning I carried about 80kg(me) plus 250kg of building materials. Almost all placed in the rear seat area (18kg concrete blocks so pretty dense) and the car was still barely movable without kissing the arches.

I’ve ordered new springs so we’ll see


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Which ones?
 
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