Nige`s Golf MK2 2.0 16V Turbo track car with Aero. www.pinderwagen.com

After my previous Bump Steer correction, I was pretty happy with the suspension. However, after the rack moving issue, I thought I`d use the opportunity to re visit and try and get it even better.

This was the last travel toe change graph I made and I wasn`t sure why the ends both went the same way.


Whilst the previous method I used was pretty accurate, it was time consuming. I looked around and thought the Longacre gauge was a good starting point.


Before going any further I removed the tie rods and centred the steering rack by measuring how much of the rack was showing at each end


It meant the steering wheel was slightly off, but I re-centred that on the splines.

I then set both tie rods to the same length and refitted them to the car.

Alignment was now checked and before adjust any tie-rods, I loosened the rack and moved that as much as possible to get the same toe on either side with the same length tie-rods. The rack was then secured. TIGHTLY.... lol

Unfortunately, I still wasn`t able to get the rack dead-central, I needed to lengthen the offside arm more than the nearside.


Now I made a bump-steer gauge. Some 10mm plate was chain drilled and then a 5x100 stud pattern drilled.


Now a hinged frame was made, this is weighed down with a couple of jerry cans to ensure it doesn`t move on the floor. These photos from before I drilled the hole out of the middle.


On the front upright, I fastened a 6mm bolt that was filed to a point.


A Dial Gauge was fastened to the other end of the plate.



You COULD put a dial gauge on each end of the plate, then take one away from the other. By having a fixed and, you can just measure the one end of the plate. If the wheel toes in, the dial gauge reading goes down as the plate moves towards the dti,Toe out and the plate moves away, increasing the the dti reading.


This gif shows what happens with extreme toe IN as the spring extends (too many spacers between the tie rod and the hub).


Now if the tie rod is lowered too much and you get toe OUT under spring extension


The most obvious thing with this method is that you don`t need to measure every 10mm. It`s immediately obvious if you have toe in or toe out under bump. Then just add a spacer between the track rod and the hub and lift / lower the suspension again.

This is a FAR quicker and more accurate method then the previous `measure every 10mm` option.

Unfortunately, I noticed a problem in that I was getting toe OUT under compression AND rebound. This is due to the Tie rod being too long.


This may help explain it a little.




The best solution (apart from a wide steering rack) it to fit some tie-rod extenders.



I don`t have time to get some made, although that is the plan for the winter. What I could do was space out the tie-rod 5mm. I don`t want to go any more as that would reduce the amount of thread securing the tie-rod to the rack.


I also moved the Lower Ball joint in by 2mm. This needed some material removing from the end of the wishbone, marked in green, as the LBJ was touching the metal.


Removed


By doing this, I reduced the length of the track rod by 7mm. Not a huge amount, but a step in the right direction. Some rack spacers are needed to fully remove bump-steer.


Now I re aligned the tracking and then re-measured the bump steer. By careful addition / removal of the spacers, I was able to get it pretty close. You can see how I get Toe out towards normal ride height then toe out AGAIN at the other suspension extreme. ie gauge goes one way, stops and then goes backwards


For a final check, the plate is marked every 10mm then the suspension lifted / lowered, with the dti reading being measured at every 10mm.



Around normal ride height, I have no bump-steer. Once I get towards the last 20mm of bump and rebound, I get up to 8 Minutes of toe out under max compression and 6 Minutes at full spring extension.


Not ideal, I would prefer none, however, the bump steer has been far worse than this for the last couple of years so this is a marked improvement and it certainly felt less twitchy on the bumps after the first round of correction!!

 

What does 8 mins equate to in mm, Nige?

 

Obviously depends on the distance between the dti and the pivot, but with my setup that works out at under 0.5mm on a 15" wheel


The really good thing about this method is it is very quick, repeatable and VERY accurate. I removed it all as I needed to move the car, then refitted it and the readings were well within 0.05mm on the dti every time. Far more accurate than we need

 

Sorry mate, I sshould have said, at the wheel rim. I'd measure at the same points I put the Dunlop tracking guages pointers against.
Under a half mm? That's practically bugger all! Excellent.
It's something I have to fix on the Forest rallycar, it has massive amount of B-S, especially with it having a fair bit of travel.

 

Agreed, 0.5mm per side is bugger all, but if I`m doing it, I`m trying to get it RIGHT

We`ve been having an ongoing discussion on Northloop about differentials in the Golf since Feb but I parked it whilst focussing on the Brakes, Cosmetics, Cage and then the suspension.

The Diff was working fine and I stopped thinking about it. After DN13, I received a message from Marko. Who you may ask ? Well, he drives this, the Roma Tuning MK1.


It`s a 250HP, 200ft/lb N/A lightweight MK1 with lots of nice bits on it. I`ve seen it around for years, but never been able to keep up.

Anyway, it appears I`m now quicker than him "but that`s only on the straights, not in the corner" lol

Straight away he said that from watching my incar video I had a Quaife or similar ATB. When I asked why he replied that he used to have one and had to wait as long as me to get on the power, now he has a plate Diff, it`s SIGNIFICANTLY better and he`d never go back.

It`s a good example of someone going from an ATB to a plate diff and seeing the benefits. For a more road based track car, I would probably stick with the Quaife. It`s fit and forget, doesn`t wear out and works well. I stripped mine down to inspect it after 5th failed last year and the internals of it were pretty much as new, I fitted new Belvilles anyway but it just proved the Quaife is something that doesn`t need maintenance. I know I`ll be making work for myself in the future fitting a plate diff with plates that wear out, but I think it`s the right way to go for a purely track based car.

I will sell the Quaife in my spare 02A gearbox, with either 4.25 FD or 3.9 FD as I have both, just depends on what a buyer wants really. The Plate diff either a Trax-X or 3J will then go in my 3.6FD Gearbox. Both cost the same, so I`m undecided yet.


It`ll be a winter swap, I don`t really have time before Brands in December, tempting as it is.


I`m still trying to fully understand what the pre-load and the ramp angles do. Not WHAT they do, more of a `how different values change how it drives` if that makes sense ?

Gurds is also looking to get a Plate diff, as is Tom (Smudge) and Prawn. We`ve all been waiting for each other to bite the bullet and do the swap, but it appears I`m going to be the guinea pig lol

 

So did the rack alignment get the bump steer even on both sides Nige? I didnt notice your measurements from both sides?

 

Bump steer is the same on both sides BUT the nearside needs more shims between the spherical and the arm on the hub

 

Never heard of 3J Nige. Mates with plate diff, said it felt like you'd a faster rack, compared to ATB.

 

Dan, the owner used to be Tran-X until Quaife bought them out, then he started up 3J making pretty much the same thing.

 

You can hit the power before the apex, huge change in lap times
No worries about picking up a wheel with a plate so you can tighten up the suspension more, especially the back
I run a spool, once you get to the torque point they behave the same, power on oversteer baby! (lift off and it will plough though)

 

I run a Tran X diff in my Clio fitted with a 1.8t and 02J Gearbox, and i also specced supplyed and fitted the Tran X to HummuH's corrado (he initially had a Peliquin diff fitted to the 8v turbo engine), Its a by far the best mod you can do to a pure track based car over a ATB
Power on oversteer is a great feeling in a FWD car :-)

 

Well, this afternoon was frustrating, interesting and productive....

Rang Quaife to talk about the Tran-X, their Plate diff.

`I`m ringing about a TranX for my 02a, this is my car spec...xxxxx, what ramp angles and preload would you recommend?`

"Well, we don`t recommend ramp angles or preload, it`s all down to personal preference"

`But can you give me an idea of where to start ?`

"Well, it depends on how you drive and what you want..."

`OK then, I have a Quaife ATB at the moment, when I brake, what ramp angles on the Tran-X would give the same effect ?`

"Good question. I don`t know. Let me ask..."

On hold for 5 minutes.

"A /90 is similar to the ATB".

`OK, will a /45 push into understeer when braking ?`

"Good question. I don`t know. Let me ask..."

On hold for 5 minutes.

"Yes, it would."

"However, we recommend an ATB for most drivers, we tested one against an open diff and it was 4 seconds a lap quicker"

`OK, but I have an ATB already, did you test the ATB against a TranX ?`

"No, because it`s down to personal preference and how you drive...."

`OK, but isn`t the ATB the same ?`

"Well, we haven`t tested them both back to back"

"Anyway, we`d always recommend an ATB, we wouldn`t consider a move to a Tran-X a progression, even for racing.

If you are going to be racing / driving on circuits, then the ATB will be a much more efficient diff than a plate type.

The ATB is stronger, you`ll always break a driveshaft before an ATB, the plate has little pins and things inside.....and it depends on the weather too...."

They just didn`t know anything about the TranX really and were pushing the ATB type.


Next up I rang 3J, the ex-TranX staff.

The exact opposite, asked about the car, weight, power, driving style etc. Suggested 40/90 & medium preload.

HOWEVER, they are too busy and have no gaps in their production in the near future to make one for my gearbox. Booo..

What he did say was "Even though we can`t supply one at this time, I can suggest what TranX to order instead. 45/90 with 60lbs preload"

So he actually recommended what competitor Diff to buy, rather than me buy the wrong one. I couldn`t fault him at all and would certainly buy from them if they actually had one for sale for my gearbox !


Then I ran a mate who runs a Gripper on their race Clio, and had a chat about his Gripper Diff, he gave me a contact he`s dealt with and I rang them.


Spoke to Tom, he knew his stuff too. Very similar comments to 3J, with the added "look at any grid where drivers can choose a diff and they ALL run a PLATE diff. NOBODY runs an ATB if they have the option to run a plate type"

They recommend a 40/65 with 100lbs preload. The preload is high, but once the plates are bedded in, that drops to 60-70lbs.

They suggest on a car over 900kgs, running /65 is preferable, it helps balance the front axle load under braking and gives less front lockup. Darren said this was something he`d also experienced in the race Clio too.

They find on light cars a ramp angle on deceleration causes it to push wide, but once you get near a ton, it isn`t a problem and the nose still tucks in as expected.

They have one one the shelf and `will do me a discount`.


Even though the Gripper is around 100 more than a TranX, I know who I`d rather ring if I have any technical issues in the future or require assistance. For that reason alone, I`ll be going for a Gripper instead of TranX.

That and the fact Quaife don`t even recommend their own product either

 

Ah, there is nothing like customer service... and one of those examples is nothing like customer service!

 

Nige, you're already doing 7:45 around the Ring in your 20 year old Golf. Don't you think you've embarrassed the GT3 drivers enough?

 

Most certainly not lol

With Slicks, I was lapping at 7:36 pace, that was with Passenger, over half a tank of fuel and tyres that are 4 years old.

There is easily more time in the car, but it`s never been about that. I know I keep repeating myself, but my favorite laps are ALWAYS when I`m with someone else driving at similar pace. The clear, quick laps are often a bit `yeah, whatever. So what`, but the ones where you get back to the carpark and you and the other driver are both as enthusiastic about it are the best ones by far.


Notso Swift, yup, agreed. Whilst I look round for a good price on things, I`ll be paying extra to go for a Gripper over TranX PURELY based on the customer service and info before purchase

 

Would be good to see it go around Mount Panorama (AKA Bathurst

 

I'd pay to see that. :thumb:

 

Disappointing that, Quaife have always been quite useful when I've spoken to them.

Luke will know better, but think my ramping was set at 40/70, not sure on pre-load. Some of what they say is right though, you really want to know what you're looking for when considering the ramping. I trail brake the car quite heavily and find it turns in very well, too well sometimes which needs a correction. Not because the rear end has gone but because the front has turned in too well. I'm on throttle before apex through the exit and have found the TranX really helps pull the car towards the apex and helps limit understeer/traction loss on exit when on throttle too.

After running it for 2 years now it's a major step up from the Peloquin for track/race work.

 

Yep 40/70 and a 70lb preload on yours
Interesting comments about Quaife, not the first time ive heard it either! We have alwase had a good experience with them, but i usually tell them what i want.. i think it depends on who you speak to about the Tran X stuff tho, not alot of them are clued up about them as there still a relatively new product to them, however if you do ring them again speak to Dave King

Worth noting that the Tran X comes with dual ramps, so you can actually spec 2 sets of ramps and swap them round if you need to, and pre load you can set yourself anyway.
The Gripper is a better brand diff, theres no 2 ways about it, but in terms of performance, i dont think you would see any difference between the 2, so its down to service and cost at the end of the day.
Its a shame Ricardo stopped the VAG stuff, the one i used to run in the Leon cup car took so much abuse and never missed a beat and there was so many plates shims and ramps available...

Also, make sure your drive shafts and CVs are good and keep checking them, you will find you go through CVs a lot faster with a plate diff :-)

 

This has been mentioned elsewhere too, which is a little concerning if I`m honest