MK5 Golf GTI

All Things Mk5 => How to Guides / Troubleshooting => Topic started by: D2TPP on March 05, 2023, 01:50:52 pm

Title: Mk5 rust removal, new sills and subframe rebuild
Post by: D2TPP on March 05, 2023, 01:50:52 pm
Hi Folks,

After daily driving my mk5 for a few years, about a year ago I took it off the road to sort out a few spots of rust.. I started off thinking it’d probably be a new wing and a small patch repair on the sills.  A year later I’m getting ready to put it back on the road after a fair bit of work!  I’ll share some pics below…

It started with a few spots of rust on the surface of the sills and one wing.. but once I got the paint off the rust was far worse than it looked.

(https://i.postimg.cc/QdGcjrJp/E3-D7-EFFC-7-D10-4354-BA73-00-B9-F80-AA68-C.jpg) (https://postimages.org/)

Once the sill covers and under-trays, arch liners were off I stripped back the paint with a wire wheel and the rust was way worse than expected.

(https://i.postimg.cc/G2B84qZf/30-FBBDD7-D929-4-DC6-9-AC0-578-F01299-F5-B.jpg) (https://postimages.org/)

(https://i.postimg.cc/BQ5Xd9qN/AD2-E12-C3-D551-4272-98-BA-86-E31-EBCE844.jpg) (https://postimages.org/)

There were several holes in the sills and the rear of the sills where dirt had gotten stuck behind the arch liner.

To get access and also to inspect the extent of the rust further I dropped the rear subframe, which looked like it had been sitting in a canal..

(https://i.postimg.cc/nh0mXKs9/DEA3260-C-FF6-E-402-E-B464-16-CD661-C8434.jpg) (https://postimages.org/)

I also dropped the fuel tank to get better access and to avoid any accidents when welding!

(https://i.postimg.cc/hv3WY1C9/AF9-E06-C9-4140-4-BEE-A87-B-93-A9016765-C7.jpg) (https://postimages.org/)

Underneath was mainly surface rust.. but it still took a few long days with a knotty wheel on a grinder to shift it.  Once removed I covered in rust protection and some acid etch…

(https://i.postimg.cc/44pMcnXQ/73-B6-CC70-AE6-F-4507-93-B6-0-BF9-E32-BEFD3.jpg) (https://postimages.org/)

I decided because of a couple of holes and a fair bit of surface rust to cut the sills off and weld on new ones.  I decided to keep the top half and weld the new ones below the line of the sill covers.. only coming up at the very front and back edges where the rust was bad…

(https://i.postimg.cc/gjfk1JBD/49-D5-F435-8682-420-D-9338-C8-C24-CC2118-E.jpg) (https://postimages.org/)
 
I’m glad I did as once cut off they were pretty crusty inside.. thankfully the inner sills were pretty solid and I only had to patch two small areas. Here is a photo mid weld…

(https://i.postimg.cc/nzqXZqBW/8-C5-B8-DE0-EFC1-470-F-B22-D-BC15662-A204-E.jpg) (https://postimages.org/)

The sills were fully welded and primed.. it’s worth noting, I decided to remove the interior during all of this to avoid any chance of it catching fire or being damaged by sparks etc.

(https://i.postimg.cc/hjZMVyZR/45-E73-F52-2-A70-4-E12-AD6-A-22-FCDAEF2-AD2.jpg) (https://postimages.org/)

With that done, I couldn’t exactly put on the old subframe.. so I set about finding a new (old) subframe and got a bit carried away buying alloy hub carriers and wishbones etc

(https://i.postimg.cc/02CPvc3m/0-DC041-B1-2-CB5-42-D1-8838-3-C72-E513-D65-E.jpg) (https://postimages.org/)

…and brakes and suspension and a big bag of bolts from tps  (some out of necessity for the alloy hubs)…

(https://i.postimg.cc/SxyhTjNQ/FFA88630-561-F-4610-BC9-D-B19140-A9-D750.jpg) (https://postimages.org/)

With the subframes refurbed and fitt d with new bushes etc. it was time to clean the underside one last time and give it a few coats of Upol

(https://i.postimg.cc/bY7Rxjz0/EC406-C4-E-4355-4-F4-D-AD23-807258-B32452.jpg) (https://postimages.org/)

I’ve now got the subframes back on and it looks like everything fits..

(https://i.postimg.cc/WpQcbw84/033-AF4-FE-86-A3-4-DCF-8951-61-E3983-F1484.jpg) (https://postimages.org/)

I’ve replaced pretty much everything so it is looking nice and shiny!

(https://i.postimg.cc/j2k5Lw8b/B5-D550-A5-57-CE-49-B0-8-DB8-233-FAA680-B25.jpg) (https://postimages.org/)

Last things below the car are finish fitting all these bungs and make up new brake lines.

(https://i.postimg.cc/tTKvy2bQ/F6-DF09-D4-86-FA-48-F6-A91-F-098-C470-EF9-B0.jpg) (https://postimages.org/)

Above the underside still have loads to do, finish sanding and filling paintwork, paint the whole car, fit the interior etc.

If you have any questions about anything above I have several hundred other photos and I think I can remember most of what I did.  I should also note, this was my first time taking on a project like this having never welded before and I had to teach myself as I went.. hence it taking about a year.  I also work full time and have a family, so I only get the odd evening to work on it.

I’m looking forward to driving it again in the near future.
Title: Re: Mk5 rust removal, new sills and subframe rebuild
Post by: Clarkj93 on March 05, 2023, 02:58:26 pm
Awesome write up mate! :happy2:

Wish I had a pit to use... not sure if I can sufficiently do my underside on an un-level driveway for weeks/months. I'm planning on doing the rear subframe though soon, what steps did you take to do the control arms and subframes? Looks like it would be difficult to get every aspect of surface rust in all the crevices. What did you use for paint/seal?
Title: Re: Mk5 rust removal, new sills and subframe rebuild
Post by: D2TPP on March 05, 2023, 03:48:49 pm
The subframe I got from eBay for £60 had practically zero rust! So that was a big bonus.  The downside was it was from an Audi a4 and didn’t have the rear bracket for the exhaust and the mounting point for the arb are about 10mm closer together that on the gti?!  I managed to cut off the exhaust hanger from my old subframe and weld it.  The arb, I’ve just moved the bracket along a little and filled in the gaps with 3D printed bushes.. but I’ll redrill new holes if I need to.

I bought new arms all around, which came powder coated.  I sprayed black stone chip on everything to give a bit of extra protection and to avoid scrapes when bolting it all back together.

As for the body work, the main bits were all done with a knotty wheel on a grinder and on a drill.  I took a fair bit of the seam sealer off to get all the rust away.. so it took a while to reapply all the seam sealer and prune the bare metal before using Upol.

Yeah really lucky to have access to a pit!
Title: Re: Mk5 rust removal, new sills and subframe rebuild
Post by: Clarkj93 on March 05, 2023, 04:03:59 pm
Where did you buy the arms from? If aftermarket, which brand and was fitment OK? And are rhey identical? Like any difference in thickness or construction in anyway?
Title: Re: Mk5 rust removal, new sills and subframe rebuild
Post by: D2TPP on March 05, 2023, 05:03:16 pm
Got the arms off eBay, identical thickness and 10x stronger than my crusty old ones.  Digging through my eBay I got them for £100 from ‘parts for you’.  We’ll see how well the bushes fare, but I didn’t want to poly bush it all just yet. And again will be much better than the old subframe where every single bush was gubbed!


(https://i.postimg.cc/d0PRvMrS/03621-E73-E544-4-D70-84-B1-73-ED05121-FE7.jpg) (https://postimages.org/)
Title: Re: Mk5 rust removal, new sills and subframe rebuild
Post by: Guy123 on March 05, 2023, 06:01:59 pm
Great write up! Where can I find a list of all the parts/part numbers needed?
Title: Re: Mk5 rust removal, new sills and subframe rebuild
Post by: D2TPP on March 05, 2023, 11:30:56 pm
Great write up! Where can I find a list of all the parts/part numbers needed?

I’ve got it all saved in my AUTODOC and eBay past purchases.  The only tricky bit was working out the longer bolts for the alloy hubs.. it wasn’t too tricky though and the guys at my local tps in Dundee were really helpful.

If there is anything you need to know the part number for let me know.
Title: Re: Mk5 rust removal, new sills and subframe rebuild
Post by: D2TPP on March 05, 2023, 11:38:39 pm
I managed to get the hard brake lines all made up and installed today.  The rears were a doddle, the front drivers side was a massive PITA.  I managed eventually though, it routes right along the ‘firewall’ / back of the engine bay, you have to remove a whole bunch of stuff if you want to keep to the original routing.

(https://i.postimg.cc/FKH1gtBG/EEDBE092-866-C-46-BE-9616-364610-AFD7-FD.jpg) (https://postimages.org/)

If you start at my red pipe cutter on the right of this photo and follow the copper coloured line.. you’ll see what I mean.

Anyway, managed to make them all up and finished fitting the braded lines to my refurbed calipers.

(https://i.postimg.cc/4xJ3sksZ/D1-E1-C220-2683-4-FB3-AE31-8-CAFA0587-B5-F.jpg) (https://postimages.org/)

Didn’t get around to bleeding them.. but I’m guessing I’ll need to get the car running and use VAG com to activate the ABS to bleed them??

If so I might try and get the interior put back in next.
Title: Re: Mk5 rust removal, new sills and subframe rebuild
Post by: D2TPP on March 07, 2023, 11:49:43 am
(https://i.postimg.cc/kg2rj9ds/123-C205-F-3-C9-D-477-B-83-DB-F5-CA3-D7041-F8.jpg) (https://postimages.org/)

Finally got the car off the pits!  Going to try and remember how the interior goes together later this week 🤪
Title: Re: Mk5 rust removal, new sills and subframe rebuild
Post by: Flyingscotsman on March 08, 2023, 07:14:33 am
Great thread!   :happy2: Glad you said it took you a year.  When you post up the photos together it looks like it was last weekend's project.
Title: Re: Mk5 rust removal, new sills and subframe rebuild
Post by: D2TPP on March 08, 2023, 05:58:48 pm
Nah it took fecking ages 😂 I only got to it the odd weekend here and there.  But it certainly wasn’t a weekend task!

The trickiest part was welding the sills.  The originals are laser welded from the factory.  They are also made from pretty thin metal.. so experimenting with different techniques to make sure the continuous welds didn’t blow through and even just taking the galv off the new sills and priming and painting behind etc. took weeks and weeks to figure out and more weeks and weeks to execute!  .
Title: Re: Mk5 rust removal, new sills and subframe rebuild
Post by: GilesWoodward59 on March 08, 2023, 10:35:18 pm
Good job on tackling that all yourself!!
Title: Re: Mk5 rust removal, new sills and subframe rebuild
Post by: D2TPP on March 11, 2023, 05:03:06 pm
Managed to get a bit more done this week, got the interior back in, got the back of the wings cleaned and covered in Upol.  One major PITA was the rear middle seat belt which was completely jammed.  After a bit of research.. smacking it with a rubber mallet and leaving it for a while managed to sort it.

The interior wasn’t too bad going back in… although I had forgotten about some of the trim I had broken when removing.. so another £60 or so on bits and bobs off eBay it was!

In preparation for putting ignition on to bleed the brakes, I had a look under the bonnet.. which reminded me I hadn’t put back the wiring loom to the power steering rack  :sad: I’ve watched a few vids on YouTube and it looks like it should be possible without dropping the steering rack *fingers crossed*. 
 
(https://i.postimg.cc/wTKgvzpB/2-D842749-64-DE-4-B12-B1-F7-9-FA96-AA7-FF14.jpg) (https://postimg.cc/rz9vnvz6)

(https://i.postimg.cc/T1bx97rG/31-EB79-A3-F736-4-A9-B-B7-A5-68-A7-F0-EF7086.jpg) (https://postimg.cc/wR9nxkfb)

(https://i.postimg.cc/HsQH8NY9/C9-ABCF50-0-ACA-4329-ADA8-2-B369412-D3-F9.jpg) (https://postimg.cc/tYC8L2Vs)



(https://i.postimg.cc/fyxgQ128/89-A99-C9-B-B07-F-42-C4-AD78-C65397-DDC3-EE.jpg) (https://postimg.cc/fSRvxqhd)
Title: Re: Mk5 rust removal, new sills and subframe rebuild
Post by: Sean_ED30 on March 15, 2023, 10:37:18 pm
Great write up. I'm planning on doing something similar with the rear subframe on my car, In the picture it looks like you have used alloy hubs on the rear ?
Title: Re: Mk5 rust removal, new sills and subframe rebuild
Post by: D2TPP on March 17, 2023, 01:55:40 pm
Great write up. I'm planning on doing something similar with the rear subframe on my car, In the picture it looks like you have used alloy hubs on the rear ?

Yeah I’ve put on Alloy hubs all round.. not had the tracking set up yet.. but it all seems to fit!  I believe they are from a Passat.. the alloy wishbones on the front are from an s3.. but i understand you can also get these from a Passat
Title: Re: Mk5 rust removal, new sills and subframe rebuild
Post by: Sean_ED30 on March 18, 2023, 10:24:00 am
Great write up. I'm planning on doing something similar with the rear subframe on my car, In the picture it looks like you have used alloy hubs on the rear ?

Yeah I’ve put on Alloy hubs all round.. not had the tracking set up yet.. but it all seems to fit!  I believe they are from a Passat.. the alloy wishbones on the front are from an s3.. but i understand you can also get these from a Passat

Thanks. I have the front S3 hubs and control arms already fitted.  I'll have to look into the rears as well if I decide to renew the back end.
Title: Re: Mk5 rust removal, new sills and subframe rebuild
Post by: LC5F on March 19, 2023, 02:27:28 pm
Great work  - I rebuilt the rear axle & subframe on mine - terrifying how rusted mine was, also finding out the majority of the bushes were seized was a shock too - I went for PSB poly bushes, and they seem to be holding up.
Title: Re: Mk5 rust removal, new sills and subframe rebuild
Post by: MrFernze on May 12, 2023, 08:35:35 pm
Did you upgrade the power steering control unit or whole steering rack to Gen3 as I've just recently had a problem with mine ? :)
Title: Re: Mk5 rust removal, new sills and subframe rebuild
Post by: D2TPP on May 13, 2023, 06:24:01 pm
Did you upgrade the power steering control unit or whole steering rack to Gen3 as I've just recently had a problem with mine ? :)
Not yet? I’ve had the subframes on and off that many times, it wouldn’t phase me taking the steering rack off again if I end up with a problem. 

Car is almost finished now  :driver:  Just waiting for slightly warmer weather to get the body work finished, then to need to decide what colour to paint it.. then paint it and put the wings and bumpers back on.
Title: Re: Mk5 rust removal, new sills and subframe rebuild
Post by: MrFernze on May 26, 2023, 11:35:34 pm
Did you upgrade the power steering control unit or whole steering rack to Gen3 as I've just recently had a problem with mine ? :)
Not yet? I’ve had the subframes on and off that many times, it wouldn’t phase me taking the steering rack off again if I end up with a problem. 

Car is almost finished now  :driver:  Just waiting for slightly warmer weather to get the body work finished, then to need to decide what colour to paint it.. then paint it and put the wings and bumpers back on.

I installed the whole Gen3 steering rack as the Gen1&2 is a common issue later on. Just remove subframe, uninstall steering control unit and then install the Gen3 version. I got mine from Wigan VAG (Danny) for pretty cheap.
Title: Re: Mk5 rust removal, new sills and subframe rebuild
Post by: BillyTahir on June 11, 2023, 12:38:09 am
How much where the new bolts and nuts from tps for subframe and control arms etc?


Good progress so far, im starting mine next week
Title: Re: Mk5 rust removal, new sills and subframe rebuild
Post by: Clarkj93 on June 11, 2023, 12:44:12 am
Just for info... I had my subframe and control arms professionally Removed, sent off for sand blasting, powder coated and fitted with new super pro bushes provided by me for about £1300, that does include 1 new control arm as one was unrepairable. Worth doing yourself it you have the resources but otherwise expect that kind of pride.
Title: Re: Mk5 rust removal, new sills and subframe rebuild
Post by: D2TPP on July 19, 2023, 02:53:06 pm
How much where the new bolts and nuts from tps for subframe and control arms etc?


Good progress so far, im starting mine next week

From memory I didn’t have much change from £200 might have ended up a bit more as I forgot a few of the main ones!

Good luck! It wasn’t that bad a job.
Title: Re: Mk5 rust removal, new sills and subframe rebuild
Post by: D2TPP on July 19, 2023, 02:56:29 pm
(https://i.postimg.cc/rwCRnm5c/IMG-6798.jpg) (https://postimg.cc/jD2jCR8k)

I Haven’t managed to do much the last wee while, but I’m determined to get it on the road by the end of Summer.. just stripped the door skins and everything else I could for painting.  About 1/10 of the way through sanding and preping the panels for paint.


(https://i.postimg.cc/v8gXZpJ9/IMG-6853.jpg) (https://postimg.cc/bdP16FNN)
Title: Re: Mk5 rust removal, new sills and subframe rebuild
Post by: D2TPP on August 11, 2023, 12:11:32 am
After a lot of sanding, filling, sanding, cleaning, cleaning and cleaning.. I finally got some paint on the car!  It was my first time painting a car, but I’m over the moon at how well it’s turned out.  I’m looking forward to painting my next couple of projects now!

(https://i.postimg.cc/Kz7jRjvd/IMG-7234.jpg) (https://postimg.cc/FdRN69SZ)

(https://i.postimg.cc/wM0BQrN2/IMG-7246.jpg) (https://postimg.cc/7JJDxmmJ)

(https://i.postimg.cc/445nGY0c/IMG-7349.jpg) (https://postimg.cc/Z0WJF54Y)

I need to finish cleaning all the plastic and restoring the headlights before putting it all back together, but won’t be long until I get the car back on the road  :driver:
Title: Re: Mk5 rust removal, new sills and subframe rebuild
Post by: Clarky on August 11, 2023, 11:39:37 am
Looks incredible ! Great set up you seem to have with a pit and a spray booth too....very jealous indeed...
Title: Re: Mk5 rust removal, new sills and subframe rebuild
Post by: D2TPP on August 19, 2023, 08:09:09 pm
(https://i.postimg.cc/T2K0Wc9P/IMG-7555.jpg) (https://postimg.cc/yWzcMc2q)

Inching closer to getting it on the road  :driver:  Still need to clean up and fit the side trims and get back under the car to finish connecting up the fog lights etc.  and try and remember how the hell all the wiring on the boot lid goes back?!  I am really liking the colour though, pretty chuffed with it.
Title: Re: Mk5 rust removal, new sills and subframe rebuild
Post by: mk1_dave on October 01, 2023, 10:49:19 pm
Looking good :smiley:

I have plans to do the same with the underside over winter, how did you mount the hard line for the rear brakes that runs along the top of the subframe? also do you have a part number for the alloy rear hubs you bought or know what car they came off?

Thanks
Title: Re: Mk5 rust removal, new sills and subframe rebuild
Post by: D2TPP on October 19, 2023, 09:39:20 pm
Thanks Dave,

The hubs were off a b6/b7 Passat, I had to buy some longer bolts for a few of the components due to the alloy being thicker than the steel, but they were a straight fit.  For the bolts I took the original ones to TPS and said ‘you got one 20mm longer than this’ etc, but also had a look at their diagram for the b6.

For the brake lines I used the original clips that attach to the rear subframe, which wasn’t too bad.  My daily driver at the moment is a mk1 TT and the rear lines for that were a pain in the arse! 

I’ve added a screenshot below from eBay for the 4 hubs I bought.

(https://i.postimg.cc/x1VnbDxk/IMG-9010.png) (https://postimg.cc/ppCgg7tx)