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When changing the waterpump/cambelt on my daughters Polo, the friend doing it commented that the front subframe was badly corroded (hole in one place) and it would fail its next MOT in Feb. I've found a replacement on eBay and will swap it out once theres a break in the weather. However I'm not aure if I need to replace the bolts? One search mentioned they're stretch bolts and should be replaced. But when I searched for the bolts they look like they're threaded end to end with no "stretch part" and dont look like stretch bolts at all.
Can someone confirm if they need to be changed or can be reused (and the correct part number for them).
Also any hints on how to make sure I properly align the replacement subframe to avoid problems with camber/caster
Thanks
Last edited by L162LZ on Tue Dec 12, 2023 7:01 pm, edited 1 time in total.
Most of the suspension bolts are one time use bolts or torque to yield type bolts ,so yes to correct thing to do is to replace them and they will as you have pointed out look like 'normal' bolts
'A torque to yield fastener (TTY) or stretch bolt is a fastener which is torqued beyond the state of elasticity and therefore undergoes plastic deformation, causing it to become permanently elongated.'
For the actual fixing bolts for the subframe, as all 4 are torque to yield so you need to buy new ones, but, after swopping the subframe you should get a 4 wheel alignment carried out on that car - or you could find that it "eats" tyres and does not feel quite so good to drive, so, fit the new subframe bolts and only torque them up to the initial torque setting, and leave the workshop that does the alignment to retorque them including the extra angle tightening.
My wife's August 2015 VW Polo 1.2TSI 110PS 6MT ended up with one of the front subframe bolts snapping its head off maybe before last winter!
I found the bolt head on the garage floor, if I had not noticed or found that I'd think that it would still be running around with only 3 out of the 4 subframe fixing bolts in place!
There was a lot of rust on the threaded section left inside which I managed to unscrew, where these front subframes bolts bolt onto the body of the car there is an enclosed or nearly fully enclosed box section - and in use it can fill up with water from road spread and so salt water in winter in places like Northern UK! Two possibilities, these bolts were over torqued at the factory or at the main dealership - not good!
So I bought a set of new bolts, even for the 2 rear brackets, fitted a new bolt to replace the missing one and just torqued it up to the first stage, then got the 4 wheel alignment carried out on it after replacing the other bolts.
Edit:- sorry I used the number for the same sized/type bolts for the 6C 1.2TSI, your number is correct and I'd think that the torque will be the same, I've no idea why the bolt number changed for the same size of bolts though!
Later:- I checked my Haynes repair manual for 6R and the torque for these 4 support(sub frame) bolts is the same.
RUM4MO wrote: ↑Sun Nov 19, 2023 3:55 pm
M12 X 1.5 X 75mm 4 – off 70Nm +90 Deg.
Edit:- sorry I used the number for the same sized/type bolts for the 6C 1.2TSI, your number is correct and I'd think that the torque will be the same, I've no idea why the bolt number changed for the same size of bolts though!
Later:- I checked my Haynes repair manual for 6R and the torque for these 4 support(sub frame) bolts is the same.
Thanks for confirming, really appreciated, bolts are ordered and replacement subframe has arrived from eBay so just wirebrushed and applied some rust converted ready to treat with some spray hammerite (was from a 2013 A1 and in really good condition with just some light surface rust on the edge seams) bargain for £34 delivered!!
Will get it changed in next few weeks (changing track rods and ends at the same time), and will leave the bolts tightened to 70Nm and book it in for 4 wheel tracking before fully tightening them. in case the frame needs to be shuffled along a bit as part of the alignment.
That's good news, I was concerned originally just in case you had just bought "any old" Polo/Audi/SEAT/Skoda small car subframe, but I've checked and see that both your car and the 2013 A1 with the 1.6TDI used the same subframe p/n 6R0 199 315 L.
RUM4MO wrote: ↑Tue Nov 21, 2023 6:56 pm
That's good news, I was concerned originally just in case you had just bought "any old" Polo/Audi/SEAT/Skoda small car subframe, but I've checked and see that both your car and the 2013 A1 with the 1.6TDI used the same subframe p/n 6R0 199 315 L.
Have fun!
Thanks, no I checked first and hunted around to get the best one I could. The ones advertised for the Audi A1, seem to be strangely cheaper, and in much better condition than the ones advertised for the Polo even though theyre the same part number , no idea why!!
