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Audi TT-VW Golf R32 spindle and lower control arm conversion-mk4
Converting to the Audi TT/VW Golf R32 spindle and/or lower control arms
The Audi TT/VW used sportier suspension pieces than the Jetta/Golf/New Beetle (A4) TDI. This DIY shows how to convert to the Audi TT suspension. In my opinion, if you just want big brakes for your TDI, stay with the 1.8T/VR6 spindle. Remember, it's not necessary to use the TT/R32 spindle to use the TT/R32 brakes, the brakes will bolt onto the 1.8T/VR6 spindle but not your TDI spindle. There are two levels of conversion: spindle and ball joint alone OR spindle, lower control arm (LCA), front sway bar, and ball joints. Below is a picture of a TT spindle vs. the 1.8T/VR6 spindle.
The biggest advantage of using the more complex TT/R32 conversion is adjustable camber on the TT lower control arm (LCA). You could use a camber plate or a LCA mod kit if you just need adjustable camber. The Audi TT LCA has larger and stiffer front and rear suspension bushings which will improve handling. (The large bushing will also fit in all mk3/mk4 LCA). Using the TT spindle alone does not give you adjustable camber, you have to convert to the TT LCA because that's where camber is adjusted from. Some other differences: TT/R32 LCA are cast metal vs. the stamped steel of the 1.8T/VR6. The solid part is stronger but it's also heavier (about 5 lbs more each). Pictured below is an Audi TT LCA and a closeup with measurements showing the elongated holes for adjustable camber. Also note the nub on the LCA. You may need this nub for the sway bar links, some don't have the nub. I've heard that 2001 cast arms have this nub but others have said they don't. The problem is that non-nub arms have the same part number as arms with the nub. More on this below.
Below is what the TDI A4 body control arm looks like. It's stamped steel and the rear bushing has spaces vs. the solid bushing above to allow more compliance.
Dimensions of the Audi TT LCA, note the elongated holes for adjustable camber.
8N0 407 151D - Left Audi TT/VW golf R32 (mk4) lower control arm
8N0 407 152D - Right Audi TT/VW golf R32 (mk4) lower control arm
8N0 407 255E or 8N0.407.255B - Left Spindle
8N0 407 256B - Right Spindle
8N0 407 365B or 8N0.407.365A - Balljoints x 2
estimated dealership price: spindles for the R32 for $287 each. $574 before taxes.
Impex has the parts (linked above) for $230 and $246 = $475 w/o shipping.
Also note that there are 2 versions of the Audi TT LCA, pictured below. The early style has smaller bushings and is only available used, the new style has larger bushings (bushings are direct fit into all mk3 and mk4 TDI). Also make sure your LCA has the nubs for drilling a spot to attach the sway bar endlinks (more details below)
Detailed procedure below
The parts list above has a few combinations that you can mix-match, read this page and then figure out what you need. Your two choices are: spindle/ball joint conversion OR spindle/ball joint/LCA/sway bar conversion. To use the TT/R32 spindle, modify the TT ball joints yourself to fit the existing TDI lower control arms, the rest is direct bolt on. You also have to turn the tie rod ends upside down. You do not get adjustable camber. To use the TT/R32 spindle/ball joint/LCA/front sway bar, you have to modify the lower control arms to accept the TDI sway bar end links, the rest is bolt on. You do get adjustable camber. Original and helpful forum threads can be viewed here: http://www.myturbodiesel.com/forum/f5/nb-build-out-atl-ga-panama-central-america-trip-2268, http://forums.vwvortex.com/zerothread?id=1254442, http://forums.vwvortex.com/zerothread?id=1724405, http://forums.vwvortex.com/zerothread?id=2062529 . I've basically summarized and organized all the most important info from many forum posts on this page..
Also note that the Audi TT had two versions of the LCA, there was a recall to make the TT more stable and give it more understeer. The specific modifications consisted of new front lower control arms with larger, softer, offset front bushings, as well as modified front and rear shocks with stiffer compression and softer rebound dampening to reduce weight transfer from rear to front when braking. The front sway bar was increased in size from 19mm to 20 mm, while the rear was reduced 1mm in diameter from 15mm to 14mm. The result in handling was slower steering response, increased understeer, and reduced lift-off oversteer.
To use the Audi spindle/ball joint only
Other than turning the tie rod end upside down to fit the spindle, the only other modification you need is to grind/drill the Audi TT ball joint to fit the A4's LCA. It's not possible to drill out the LCA for adjustable camber because it's stamped steel and doing so would weaken it. The Audi TT LCA is cast so it can withstand the elongated holes for adjustable camber. The spindle also has a better camber curve
Below is a TT spindle with an A4 LCA. Note that the LCA is stamped steel.
To use the Audi TT spindle/ball joint/LCA/front sway bar conversion
The biggest obstacle is finding a place to mount your stock sway bar end links if you choose to keep the stock front swaybar. Some Audi TT/R32 LCA have the nub for drilling out a spot to mount your current sway bar end links, some do not. If you do not want to keep the stock front swaybar or your TT/R32 LCA do not have the nubs,, you have to get a TT front swaybar, TT front swaybar endlinks, and new TT struts. The 1.8T/VR6 sway bar goes over the axle, the TT/R32 swaybar is less likely to have no clearance issues since it goes under the axle.
Remember, if your LCA does not have the nub, you must get TT/R32 struts to connect the swaybar endlinks. If it does, you can drill the LCA out and reuse the stock swaybar endlinks. This is pictured below and in a picture above.
Also note that there are several different bearings for the Audi TT spindle. The bearings have different part numbers, and cars that came with an 18 inch wheel package from the factory will have the appropriate bearing for the 20ths. If getting TT spindles, your best bet is to find R32 spindles if you don't want to replace wheel bearings or modify the axle bolt from the 1.8T/VR6 spindle.
Below is a modified Audi TT LCA with drilled out hole. Note the nub which the swaybar endlink is bolted to.
Procedure and pics below from Richard55 at myturbodiesel.com
Put the LCA in a vice as we are going to drill it out to 10mmx1.5 pitch. Center punch the LCA in the center of the knub.
Before you drill figure out how deep you need to go by installing the bolt into the old LCA with the sway bar bracket in place. Then use tape to mark the depth. You will need to go a bit deeper to get it to fit correctly. If you don't go deep enough the bolt will not bottom out on the bracket and it will be loose, but don't worry too much you can always trim the bolt some to fit. I had to lol.
Start small, keeping it straight and work your way up to the tapping bit size.
Again mark the depth you need to go on the tapping drill. Go for it, just keep it straight and not wobbleing side to side.
Tap the hole, install the LCA on the car and install the sway bar. Done Audi TT LCA now works with the NB sway bar.