Re-drilling mk3/4/5 front hubs

[Luke]

all this talk of hubs redrilling and i eventually got round to measureing up to see what will go on now those with mk1/2 have no worries the hubs are flat and you can fit what you want on - ive done a set of 112x5 (mercedes) on mine and they fitted no probs- ive since taken them off and fitted a mk4 front end to get me the coil springs and rack - so i need to look at redrilling the mk4 - but i then found mk4 is wider and my alloys wont fit even if they are redrilled but............. for the benifit of anyone else wanting to have a go here's what i found

the main problem with the mk3/4/5 (and i'm assuming mk5 is the same but i havent examined one closely) is they have a recess in the hub exactly where the redrilled hole would ideally sit

as a side issue the mk3 hubs are different to the mk4 ones - different bearings

what ive done here is cut a piece of paper to the same pcd as the wheel studs 12mm to show where the hole will land

112 x 5 mercedes/granada PCD

120 x 5 BMW/JAG PCD

OK so its not perfectly accurate but gives a good enough idea

My conclusion is the BMW is ok so if you wanna fit alloys go for BMW the mercedes ones is touching too small - i wouldnt go any smaller also the stud could be fitted closer to the hub bolt and the stud head could be cut away to allow the bolt to pass through also the recess could be filled with cold weld - or mabe welded up - but im not sure about that

if you think about what could go wrong, theres no chance the stud will pull through what would go wrong would be the thin wall crack and the stud come out that way but it's connected at the other side and the entire piece if cracked would have to move -but i dont think there is sufficient force for it to do that, end of the day it's up to you
this is just a rough guide - personally i'd inspect them again to see if they still look ok

[WRECKERSTEVE]

i have 94 hub off and off to machine shop with pic of your redrilled hub they may offer solution to the recess in the face just a thought what do 6 stud single wheel hubs come like with the hub machined down is there enough then and are ifs all similar from 86 on

[Luke]

hmmmm

have you got a pic of the 6 stud srw front hub

the only one ive got is a mk1/2 one and its not really suitable

[custom]

defo cant drill mark 5 hubs for 112 pcd i tried to have mine done and the enginnering shop said its not possible its too tight and would be very weak thats why i had to get spacers made

[Luke]

defo cant drill mark 5 hubs for 112 pcd i tried to have mine done and the enginnering shop said its not possible its too tight and would be very weak thats why i had to get spacers made

im not so sure - if you measure the recess its 18mm (ish doing this with a plastic ruler) and the entire hub face to face is 29mm so you have 11mm to hold the stud in counter bore - thats without the recessed bit which would still be holding the stud in placce then take 1mm off to make the stud sit flat and drill out the disk??? just a thought??? to allow it to bolt up flat not sure about this tho - i'll have a look at a disk to see how thick it is

i'm not saying it can be done, i just get something in my head and dont like to let it beat me its certanly eaiser to fit adapters but not everyone can fit a bodykit or just mabe prefer it to have standard arches

i'm half tempted to do a set for mine so i can fit the wheels on (even with the 35mm overhang) but its probly better to get my custom hubs done and put the effort into doing it properly with no overhang

if i decided to do my mk4 i'd go for 120mm or above pcd - definatly

[WRECKERSTEVE]

i had a chance to look at 6 stud hub today and it is like a twin wheel hub thats shrunk same deep dish in centre no go here, the guys who made the adaptors for me have looked at front and rear hubs of a van i have in my compound and agree that it should be possible to redrill rear hubs to suit will try on the donor hub. the fronts a different matter as you pointed out the flanges has several recesses in the face tha stop redrilling they didn't seem to confident about welding up cast iron he's giving the matter some thought but if i cant solve the hub dielema where next the hub you have in the pics are from which mk i have considered using the correct material machining a new hub this is based on the time and cost of fitting arches and modifing the existing metalwork given that i need to lower the van 4" to look ok with the 18" wheels any thoughts would ease the strain on the brain

[Luke]

the hubs in thew pics are mk4 swb

and machining a new hub is what i think i'll have to do for mine to loose 70mm on the width

rears lets keep this thread fronts

[transitgeoff]

hubs are steel not cast iron, there is no cast iron on vehicle steering components

[Luke]

i'm guessing they will be forged

[WRECKERSTEVE]

my 94 is a mk4 this has recessed front flange could you mean mk3 or is yours one that may have been change inadvertanly for a mk 3 if you machine up hubs 2 sets cheaper than 1 and what material would you use sorry to mix and match but both threads sort affect each other

[WRECKERSTEVE]

if they are forged why cant they be welded

[Luke]

yeah gets very confusing

right mk3 and mk4 (mine are definatly mk4) are almost identical but the mk3 has different bearing sizes (same as mk1/2 i think) also the recesses are ever so slightly smaller - to identify which is which the mk4 has the 2 slots where the hub nut cap sits the mk3 does not
mk5 i am assuming is the same as mk4 - almost everything else on it is but they may be different ive not had one in bits yet

[transitgeoff]

they can be welded, just have to be careful of distortion and dont bother if you have a clarke 80 amp no gas mig well not unless you wanna die

[Luke]

if they are forged why cant they be welded

im not saying they cant i just dont fancy doing it you alter the material spec, grain structure etc. creating weak spots you are effectivly adding areas of cast, it wouldnt be so bad if it wasnt on such a critical area i can have a word with some of the metalurgists at my work see what they think

[transitgeoff]

look at the adjustable tca"s for mk1 and 2 escorts, same material, welded and how much stress does that part take, especially on a rally car