My Mars Red Mk1 - Thread REBOOT- P82

Very nice update, I always wondered how mk2 uprights could be made to fit and work right.
Is the steering arm pickup on the mk2 upright the same as the mk1 seen from the length and width of the car?
I only do not really understand the taper of the flanges, where did this taper?

 

Thanks! No, the steering arms need to be longer but in my case this is not an issue as that is also custom for the widetrack that I run.

Regarding the hub taper, this is what I mean.



The wheel forces try to twist the hub inside the wheel bearing. This eventually either breaks the flange or causes a taper wear as shown in the diagram above.

 

Love it love it love it.

Gurds, if you hadn't lower BJEs, do you think the steering arm would need a massive vertical extension?

 

Hi Tristan, thanks!

Yes they would need to go up a fair bit. TBH it probably wouldn't be wise to go up that far.

Gurds

 

Great updates as always.

How is 'TAC' ? Has he still got the mk2. He's a very clever and skilled guy.

 

Hey Beetie,

If you mean my mate Tak the IT specialist, he's doing great. If you mean the guy who did the CAD work, that's not the same guy.

Gurds

 

Thanks Gurds!! Keep the updates coming!!

 

Gurds, he means Tom. lol Look at the upright drawing he did for you.

TAC is well, he still has the Mk2, although I think his may have moved less then mine in the last two years.

 

Yeah I mean smudge. I remember he uses his initials for his work.

Last I saw on another forum, he was thinking or even trying to make his mk2 super charged. All custom bravkets made by him

 

Transmission Line 6 Speed 02S



Now I run taller and wider 225-50-15s, I find the acceleration a little blunted out of 3rd gear corners as the RPM drops just under boost. So I plumbed for a 6 speed 02S gearbox to better suit my needs. Having experienced a similar 6 speed box in Rambows car, I knew what to expect. I selected the most suitable ratios for my needs based on target top speed and in gear acceleration out of specific corners. I managed to source such a box from the earlier batch of mk5 Golf/Audi A3 production. According to Hotgolf at Gas'n'gears https://www.facebook.com/gasngears/#, some of these earlier boxes have 02J differentials in them giving a wider range of diffs to choose from in the aftermarket.

My gearbox arrived so I got on and stripped it down to check the diff type.





Result! It's an 02J just as Mart said it might be. Thanks Mart.

Time to test out my new pillar drill.





I had good results with the Wavetrac diff in my current 5 speed but I really wanted to try a plate diff. With favourable results coming back from the Kaaz that Nige installed and pretty much every race driver saying Plate diff all the way, I opted for a Gripper Race setup. Fingers crossed that this isnt a mistake. Given the car is not really road driven, I can live with the inevitable cracks and bangs that these diffs are know to make in slow speed manouvers.





Fitted the ring gear to the diff.





And chucked the lot into the gearbox. Well, it's not that easy..... The 02S bell housing is incorrect to be able to run the 02j flywheel, clutch and starter motor combo. So the options are:

Change the clutch, flywheel and starter motor to mk5 golf FSI spec.
Swap over the gearbox housing to 02j.

I opted for swapping over the bell housing. I needed a spare 02J gearbox to do this to which Prawn responded and donated one to the cause! Thank you Nick!!!

This box was also stripped and cleaned, then build up process began.



First off, the diff bearings need to be correctly preloaded. With the bearings fitted, the free play of the diff is checked without any shims.





This is then used to calculate the thickness of the required shim.



It then all comes out again to fit the shim. The same process is used to measure and shim the pinion shaft. After this the re- assembley can continue.





Ready for installation.



The other concern with the transmission was clutch life. With the Gripper likely to work the clutch harder, I thought it would be best to uprate the clutch setup too. This is a preventative choice having seen what effects plate diffs have in others cars along with the next upgrade I have planned alongside, a turbo upgrade! ;0) .
I chose a long standing known upgrade. Sachs SRE Sintered race clutch and pressure plate. Rated at over 390 FT/LBs means that it should comfortably cope with my engine outputs. My main concern is complete failure rather than clutch slip so I hope this goes a long way in surviving the inevitable abuse.









And in it goes!





The box was also lifted into position. This is pretty tricky on your own but years of messing around means I get by.

Meanwhile the snail was about to be woken from hibernation...

 

For the benefit of the readers...

As you are aware, we get these sort of question come up all the time and this car is no longer owned by a novice.
Suppose you are an avid trackdayer and you have started to build confidence with your driving and your vehicle setup. Where would the benefits of this type of diff be felt over an open diff, Quaife or Wavetrack?

Secondly, many folk within competitive motorsport, tend to favour this type of differential vs the ATB brands which are popular in a track cars. What specific feature is responsible for that choice?

Important point

Thanks for the details in that update.

 

For road use, the Wavetrac/Quaife/any helical diff does what is needed without any downsides at all. A well setup chassis with a helical diff added will never leave you wanting and if anything will have the driver pulling off manoeuvres deemed far to dangerous for joe public to deal with anyway. Along with this, the helical diff requires no maintenance, is silent in operation and drives like a normal gearbox in every other aspect.

On track the plate diff comes in to it's own. Remember the difference a helical diff made to your open diff'd box the first time you tried it? Well the plate diff does that again. In comparison to a helical, the plate lets you get on power even earlier, the tug around the corner is sharper still, it pulls you eve closer to the inside of the corner and also provides better brake stability as both wheels are controlled during deceleration too. With driving adjustments, this should result in a faster lapping machine.

So what's the downsides? Well what do you think comes under more strain as a result? The rest of the drivetrain. The clutch, the cv joints, gearbox and the tyres all take more of a battering. Along with this, a plate diff requires more aggressive driving to switch it 'on'. Half hearted throttle application end in understeer and wet driving becomes more challenging. That's all after hearing the diff cracking while you pull out of your parking slot or turn into the work car park. Oh and torquesteer can be more violent too.

All that said, it is possible to buy lightweight and low preload plate diffs that have very mild characteristics with almost any noise leaving maintenance schedules the main disadvantage.

Gurds

 

I would have thought for road use, an OEM open diff is absolutely fine given the speed restrictions and proliferation of scameras that are being erected everywhere.
If the above does not deter you and you do enjoy a 'spirited' drive in the country B and A roads but do not take part in track days, usually an ATB such as a Quaife or Pelican or OBX would be acceptable?

Your answer on the plate diff, suggests this part allows more accurate placement of the vehicle into and out of a corner for an advanced driver and a vehicle setup to suit?

 

For a completely stock car yes the OEM open diff is fine. But for all the people increasing the output via tuning or engine swaps, this normally results in very low grip pulling away and bad wet weather characteristics. Early days of mk1 golf with 16v ownership highlighted this and switching over to a Quaife resulted in much better road manners in every situation full stop. I remember driving Ben Straker's Mk2 at Curby when it had a tuned ABF and suspension but an open diff. Even the slightest acceleration input with some steering angle on resulted in wheelspin and understeer. This wasn't even pushing on hard.

So for all the people fitting R32s, 1.8ts etc to their old Golfs I'd say fit a Helical diff without question.

Gurds

 

Turbo Time! - Not lagging behind


So how did I arrive at upgrading my turbo? Why would I even do that? Well I had no intention to upgrade anytime soon but I had a friend over to buy my now redundant Turbo Technics cast turbo manifold. While over, he was discussing his plans to turbo his Mk3 Golf Anniversary and said he wanted to buy a Garrett GT2860RS just like the one currently sat in my engine bay. Well lets just say we came to an agreement and he left with a turbo to go along with his new manifold. Smiles all round!

Bye bye Garrett! You have served me well.



Ready for something new.



This left me we choices again. The replacement would need to spool just as well as the Garrett and have the same very small lag characteristics. Not an easy feat given thats what the GT2860RS was famed for. I wanted the easiest replacement solution too which meant sticking to the same t28 fitment aperture or at most T3 so that I didn't have to rebuild my exhaust manifold. I was tempted by the twin scroll offerings available but again that meant a new manifold. I also wanted to stay internally gated if I could help it. Various Garret and Borg Warner options were looked at but I finally decided on a Borg Warner EFR 6258.



Being slightly bigger than my old Garret means a better top end but modern improvements on materials and design means it actually spools up quicker! The internal gates on these EFR are also known to meet the performance of external gate designs so will not pose control issues associated with internal gates.
Great! A T28 flange turbo with improved performance to bolt straight on........ Erm never is life so simple. When offering up the turbo, the diagonal support on my strut bar fouls the turbo so there was only one solution. Cut the diagonal off!



Now the turbo can sit.



I will replace the bar further along the strut brace. The downpipe will need re-doing as the new turbo has a V-Band outlet on the hotside.



The remains on of the old diagonal have been cleaned up.





This just leaves the downpipe to rebuild. Meanwhile Nige had borrowed my ECU to help diagnose electrical gremlins he was chasing. I had planned to fit a barometric corrected 4 bar MAP sensor so I sent it to him with the ECU. Low and behold, the ECU was returned with the MAP sensor fitted. Thanks Nige!







So there we have it! That is all the mechanical updates covered with the last steps to finish them off being covered as you read this now.

 

You know I was playing devil's advocate because I can lol.

Therefore in summary, if you enjoy the thrills that could be associated with driving, the addition of at least an ATB in an older car would enhance the experience by increasing grip, particularly in an out of a corner on a pretty responsive engine and gearbox combination.

Your experience over the years shows how you have developed both driving craft and vehicle to be a pretty formidable combination on track.
The case for the plate diff forms part of this evolution.

As always I am loving the updates, justifications and thought that are going into the build...

 

Finally got round to uploading some Spa laps.

Enjoy!

[video=youtube;raUXvTs3zK0]https://www.youtube.com/watch?v=raUXvTs3zK0[/video]


Turns out Matty was driving the Pinderwagen that session.

Gurds

 

Great write up - going to feel like a different car with all of the new updates!? - When you hoping to be ready for first test with the new setup?