Front strut mount replacement 'How to'

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Genesis

Top Post Dawg
Joined
Feb 26, 2003
Location
Sevier County TN
TDI
'03 Jetta Wagon
That is PROBABLY not what's going on. The rubber donuts deteriorate over time and there's a high degree of probability it's coming apart internally. I recently replaced mine on a MkIV and they were in surprisingly bad condition internally -- which was completely invisible until I removed them.
 
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steffen707

Veteran Member
Joined
Dec 7, 2005
Location
Central Wisconsin
TDI
01 Jetta GLS TDI
I recently had to pull my hub and strut assembly out to change a wheel bearing and I noticed a broken spring, so I bought new springs and while taking things apart i noticed the strut mount was just sitting on top of the nut/bearing.

My nut doesn't have a shoulder to hold the rubber strut mount onto the bearing. Is this a problem? Also I noticed there is no spacer, just the spring disc, bearing, nut and rubber mount sitting on top of all that, then with that pushed up into the fender area the limit stop and top nut are there.

Do I need the spacer, should I just replace the rubber mount with spacer and a new nut with the shoulder on it?
 
Dimitri16V

Dimitri16V

Top Post Dawg
Joined
Jan 30, 2005
Location
DE
TDI
01 Golf, 04 Golf
RacerTodd said:
Yes, all those bolts must be replaced. They are tightened to what is called Torque To Yield (TTY). This is characterized by torque specs that call for a specified torque to be applied, followed by an additional rotation of X degrees. For example, the rear lower shock bolt spec is 30 ft/lb + 90 degrees of rotation.

/geek mode ON/

When you tighten a bolt, it stretches. The bolt material has a Yield Strength and a Ultimate Tensile Strength.
If you stretch the meterial to a point below the Yield Strength it will return to its original length when you release the pressure.
If you stretch it to more than its Yield Strength, it will be permanently stretched and will not return to its original length when you release the pressure.
If you continue to stretch it to its Ultimate Tensile Strength, it will break.

Let's say that the alloy the bolt is made from has a Yield Strength of 80,000psi and a Ultimate Tensile Strength of 100,000psi.
If you tighten the bolt to less than 80,000psi, it will rebound back to it's original length when you loosen the bolt. Torque values aren't randomly chosen, they have engineering reason behind the numbers. Typical torque values aim to get a bolt to about 80% of it's Yield Strength.
Theoretically, as long as you never exceed the Yield Strength, you can tighten and loosen the bolt as many times as you want with no damage to the bolt material.

For a bolt that we want to Torque To Yield, we want to tighten it so that the stress on the bolt goes above the Yield Strength but below the Ultimate Tensile Strength. This is typically done by specifying a modest torque value, designed to clamp the parts tightly together, then using a rotation value to stretch the bolt the correct amount.
Couldn't we just specify a higher torque value? Yes, but the amount of stretch on a bolt is subject to friction between the threads which can vary depending on how clean they are as well as torque wrenches that vary in accuracy over time. Specifying a rotation value ensures that the bolt stretches exactly the amount we need regardless of other factors.

When a bolt is tightened to a TTY spec it is permanently stretched and re-using it risks failure.

TTY fasteners are many times used where you want to get maximum clamping force with the smallest possible fastener. Rod bolts and flywheel bolts, for example. It seems odd to have TTY bolts all over the suspension and motor mounts. I have a theory why VW does this, but that'll wait for another time.

/geek mode OFF/
Click to expand...
not all of them
the nuts will have to be replaced but not the bolts. the nuts deform during tightening and if reused they don't have the same holding power
 
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steffen707

Veteran Member
Joined
Dec 7, 2005
Location
Central Wisconsin
TDI
01 Jetta GLS TDI
steffen707 said:
I recently had to pull my hub and strut assembly out to change a wheel bearing and I noticed a broken spring, so I bought new springs and while taking things apart i noticed the strut mount was just sitting on top of the nut/bearing.
My nut doesn't have a shoulder to hold the rubber strut mount onto the bearing. Is this a problem? Also I noticed there is no spacer, just the spring disc, bearing, nut and rubber mount sitting on top of all that, then with that pushed up into the fender area the limit stop and top nut are there.
Do I need the spacer, should I just replace the rubber mount with spacer and a new nut with the shoulder on it?
Click to expand...
Anybody know the answer to my question?
 
SilverGhost

SilverGhost

Veteran Member
Joined
Mar 25, 2005
Location
Back in So Flo - St Lucie
TDI
'05 Golf - totaled :(, wife's '13 Beetle - buy back, TDIless
The spacer was used on certain models to help level the car, depending on equipment. It may or may not be there, and is not needed on every car. Some people have added it for a small lift (or make up for sagging springs).

If you have it apart and have time then go get the correct nut. But I don't think it will cause irrepairable harm if you don't have the shouldered nut in there.

Jason
 
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steffen707

Veteran Member
Joined
Dec 7, 2005
Location
Central Wisconsin
TDI
01 Jetta GLS TDI
SilverGhost said:
The spacer was used on certain models to help level the car, depending on equipment. It may or may not be there, and is not needed on every car. Some people have added it for a small lift (or make up for sagging springs).

If you have it apart and have time then go get the correct nut. But I don't think it will cause irrepairable harm if you don't have the shouldered nut in there.

Jason
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Thank you for the info Jason. I've realized that my mounts are worn out as well. So when replacing them i'll replace the nut with the shoulder on it as well and just forget the spacer. Its not on my car, and already the front sits higher than the rear. Might need new mounts in the rear as well?
 
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jnsrogers

Member
Joined
Jul 4, 2014
Location
Oklahoma
TDI
2005 gls TDI (BEW)
So we can purchase thicker spring mounts to achieve added height in the front? I've literally knocked 2 oil pans out this year already. One on a county road and one in a convenience store parking lot. Is there a skid plate available for my 05 MKIV?
 
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seaglf

Veteran Member
Joined
Feb 21, 2010
Location
Houston Texas
TDI
2002 Golf GLS Automatic
complete strut

I have decided to get one of those complete strut sets, or a coilover kit. I was looking at the strut set on eBay and called to confirm TDI compatibility, and the guy assured me that the TDI strut and the 2.0 gas are the same.

It seems to me that the TDI would weigh much more then the gas model. I was also looking at a 1-3 inch coil over kit. Does anyone know for sure if the weight is the same for the TDI and 2.0 gas model.
 
swanjp26

swanjp26

Veteran Member
Joined
Nov 8, 2013
Location
Escanaba, MI
TDI
2001 Jetta GLS TDI
I have found that when I have the front wheels in the air, I can move the top of the driver side strut forward and back by hand. Passenger side is solid. Do I just need new bushings in there, or will I need new struts or possibly more?
 
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seaglf

Veteran Member
Joined
Feb 21, 2010
Location
Houston Texas
TDI
2002 Golf GLS Automatic
curb

Thanks! the reason I want to replace the whole thing is that I know the bearings are shot because I ran over a curb and got screwed by Insurance and VW mechanic, they never replaced the struts or bearings. I'm afraid that the whole struts are probably bad.
Anyway they have a complete suspension kit also,Tie rods, bar links,ball joints rear shocks and springs for around 300 to.
 
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bellyboy

Well-known member
Joined
May 1, 2006
Location
Rhode Island
TDI
2001 Jetta TDI GLS, 1999 Jetta
I used silverghost's method and it worked great! Did not need compression or did not need to take axle off for either side...used my knee on tire for the passenger.

1 Car on ground
2 Took plastic cap off
3 opened ended wrench with Allen (to hold strut) - take first nut off
4 jack car up and wiggle mount out - put new in
5 lower car put cap on then put nut on and tighten
we are done...took me maybe a half an hour

thank you!
 
K

kwong7

Veteran Member
Joined
Mar 25, 2004
Location
Southern Caifornia
TDI
2001 Golf GLS TDI / White
Richptl said:
The Powerflex upper mounts came in and I can see that the metal washer inside prevents removing or installing around the inner nut. I used the Autozone free rental spring compressor and the double-nut locked together trick so the bolts don't push up into the fender. It wasn't that hard to just do it that way. The rubber mounts that came out were beat to death. The front end is almost 1" higher now so the car (a wagon) doesn't have the nose-down rake. I used all the lube that came with the mounts and then a lot more CRC special moly/PTFE lube as well.

Why did I go to Poly? They were $67 delivered. The car's a diesel and with the performance and exhaust mods will I ever hear squeaking? Hope that the poly mounts hold up and don't squish like the rubber. The roads in New York and PA are very, very bad and really beat on a suspension.

I put Audi TT bushings in the LCA rear bushing a few weeks ago. There you wouldn't want poly because you need the flexing compliance of rubber.

I have to check into the rear axle bushings. Sounds like on the MK4 with passive rear steering those mounts should also not be too rigid and should be oem or slightly stiffer but not poly.
Click to expand...
Any updates on the Powerflex strut mounts? I have 9.5 year and 160K miles on my H&R Dunebuggy Coilovers and OEM strut mounts. My car is sitting about 1/2" less than where I set it years ago; I'm certain my OEM strut mounts have compressed.
 
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sagolfer

Member
Joined
Dec 5, 2007
Location
San Antonio, TX
TDI
2005 Jetta TDI GLS
My Experience

I was able to change the strut mounts and bearings on my 2005 Jetta TDI MKIV A4 BEW without having to use a spring compressor. I used a combination of tips found here (mostly OP and SilverGhost) and elsewhere.

One key was that I was able to use a floor jack and lower the car slowly (very slowly) while holding the strut and guiding into place. I was able to hold the bottom of the strut, just below the coils. I could also see the strut through the opening in the engine compartment while I was guiding it into place. This was key for replacing the bearing and guiding the new mount into final position. I used a jack stand under the control arm.

Another key for me was that I disconnected the Sway Bar Link (top bolt and nut) which allowed the strut to drop down a lot further.

I think these were the keys to being able to do the job quickly with little effort. It was a little tight getting the new mount on the passenger side but really not much of a problem on my car.

My biggest concern and warning was how high I had to jack the car up to get the new Strut Mount in. I jacked up one side at a time just until I could get the new mount in. It seemed high. You can move the strut around and tilt the mount to make it easier. It didn’t seem to bother my car but it might yours. I’ll leave this warning and defer this to the experts.

It was a fast and easy job for me and my vehicle. Thanks to all that provided tips.
 
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