Mark 4 VW 1.8T GTi Build - RallyCross - MF Class

Because David, I moved to the south, I wasn't raised or educated here. No way I would weld it up, when I can buy the right parts the first time around. That's why I'm taking my time to build this thing, and trying to get lots of information before each step. Already made the mistake of buying the 17" wheels before I posted my build thread, and look how much flak I took for that...

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DanielSL
I cannot believe the Caddy is up for sale. Did Leon get bored with RX? Is he building something even more radical? His build is one of the most amazing things I have ever seen. He is an amazing fabricator, and competitor.

Yes, in Modified Class, if you want to win; you eventually put in a lsd.

He mentioned something about changing class in his for sale ad. https://www.sccarallycross.com/forum/classifieds/cars/for-sale/644-vw-mf-rally-pickup

We never talked diffs but something interesting, that's the second time I've seen someone do very very well with a Quaife.

The problem with welded or clutch pack diffs is you can't turn off-power... if you can't turn off-power then it really limits your options, and keeping your options open is key.

ANY diff is better than running an open diff and shearing the diff pin from one-wheel spinning. Finishing poorly is still better than finishing on the end of a rope.

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Pete Remner
Cleveland, Ohio

1984 RX-7 (rallycross thing)
1978
Silence is golden, but duct tape is silver.



Edited 1 time(s). Last edit at 09/01/2016 04:51PM by Pete.

I love being off on Fridays. Was able to do a lot of spring/strut/shock research today.

Spent a lot of time back and forth with HotBits, and my rear suspension is set, and shipping out to me. Settled for two sets of springs. Both with the 20 Kg helpers. First set will be 250-60-25 for RallyCross only. Soft dirt, sand, sugar sand, mud we have down here. Second set will be 230-60-30 for the European RallySprint track at The FIRM, so I have a little extra give on their jump, and yumps. Lots of people in CFR region running their sprints are getting air, and I don't want the car bottoming out real bad.

Was able to get a hold of Leon, and a couple of guys that run Mark III and Mark IV Golfs/GTi's in RallyCross. With suggestions from this forum, as well as dialing those suggestions in with Leons advise; I am sticking with the Bilstein HD struts, and VW Jetta springs in the 160-175 lb. range.

For the initial dialing in of the car, I think this will work a lot better than where I was originally headed. Figure 175 front, with 168 rear for RallySprint, and 160 front, with 140 rear for RallyCross.

"It's all gone quiet" said Custard..."Too quiet" said Rhubarb.

Maybe it's time for a brief musical interlude before the discussion on the preservation of VW CVs takes place.

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Disappointingly not yet a Jackass

Motor mounts that don't allow the drivetrain to bang around and don't apply power at more than a turn of lock (half turn if you have fast steering) and they should live just fine...

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Pete Remner
Cleveland, Ohio

1984 RX-7 (rallycross thing)
1978
Silence is golden, but duct tape is silver.

If I have any issues at all with CV's, I will follow Leons lead and use the Driveshaft shop Stage 2.9 axles, rated for 500 whp. He never had a failure after switching to them. It's going to take me so long to learn how to drive this thing, it will be a full season or more, before I am trying to squeeze lots of throttle coming out of corners anyways.



Edited 1 time(s). Last edit at 09/06/2016 05:23AM by DanielSL.

Ugh, DSS is a good way to spend a lot of money. A pair of $40 spares in the trunk and the tools to change it is much better for now.

The trick is, you're more likely to break axles BEFORE you learn to drive the thing, when you overshoot and end up not thinking and you go full power at full lock and the outer CV disassembles itself. Then you break the $40 axle from Rock Auto and not the $500 axle from DSS.

That's also a real good way to train yourself to not do stupid things like that!

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Pete Remner
Cleveland, Ohio

1984 RX-7 (rallycross thing)
1978
Silence is golden, but duct tape is silver.



Edited 1 time(s). Last edit at 09/05/2016 05:27PM by Pete.

Quote
DanielSL
If I have any issues at all with CV's, I will follow Leons lead and use the Driveshaft shop Stage 2.9 axles, rated for 1000 whp. He never had a failure after switching to them. It's going to take me so long to learn how to drive this thing, it will be a full season or more, before I am trying to squeeze lots of throttle coming out of corners anyways.

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John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.



Edited 1 time(s). Last edit at 09/05/2016 05:28PM by john vanlandingham.

Quote
DanielSL
If I have any issues at all with CV's, I will follow Leons lead and use the Driveshaft shop Stage 2.9 axles, rated for 1000 whp. He never had a failure after switching to them. It's going to take me so long to learn how to drive this thing, it will be a full season or more, before I am trying to squeeze lots of throttle coming out of corners anyways.

It's not the power, it's the combo of the suspension articulation and steering lock. My buddy with the 270 hp 1.8t rally Golf used to shred those "unbreakable" Driveshaft shop half shafts. In fact one broke on the opening spectator stage of the New England Forest rally. Brand new, lasted less than 2 miles while turning up the hill at the finish of spectator stage. Don't waste your money.

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Opel is a 4-letter word...
http://www.flickr.com/photos/10498579@N07/sets/

rated for 1000hp, hmm, I dunno, you might as well just go for the stage 5 ones, they're rated for one million hp.

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alkun
rated for 1000hp, hmm, I dunno, you might as well just go for the stage 5 ones, they're rated for one million hp.

But will stage 5 shafts work on stages 1,2,3,4,6,7,8,9,10 etc?

I'd be hesitant in procuring shafts that only worked on a particular stage of a rally.
Plus the cost to buy the "full set" for a long multi-stage rally and the hassle of changing them after every stage would piss off the service crew.
Shafts @ 1000 bucks is surely going to eat into a team's beer budget...

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Disappointingly not yet a Jackass

Had to edit my post. I'll be getting the Stage 2.9 shafts. Which are 500 Hp rated. Messed up on 2.9 vs. 5. Not nutty enough to spend 1500 on CV axles. 800, yes, sure.

I have two sets of freshly rebuilt CV's from the GTi's. Those handle the stock 180 Hp, as well as modified cars easily. I also have the original TT-Q 225 Hp axles. When we install the drivetrain, we will see if they will work with the Jetta sourced transmission and the GTi spindles. If they do, I will have them rebuilt, and use them, with the GTi CV axles as the spares.

Ascona; Thanks for the heads up. I will Not order a set unless I have serious issues with the stock ones. As I have 2-3 sets already (depending on if TT's will work), so if I break all of them doing RallyCross, then I will think about it again. However, that money can go other places right now, if they are not as reliable as they sound.

Danster; We should be safe then. I'm a Drambuie and Captain Morgan guy. And my team is almost exclusively Captain Morgan people as well. LOL.

What breaks in rallycross is not shafts, it is the CVs, when you're under power and high articulation, especially when it is bumpy and/or the engine is boinging around, the internal friction in the CV binds the ball to the races and breaks the cage apart. When the cage breaks apart the balls come free and the joint is done.

The "high power" axles are still going to break! You're not going to be twisting and breaking axle sticks, that isn't the weak point until you get up into ridiculous power. Heck I know people who DO make that kind of power and the CVs are never the problem, it's always the axle sticks. (I'm pretty sure it's the same joints that VW used on the A4 chassis cars too, 108mm right?) But you're not driving a 1000hp all wheel drive car. The "upgraded" axles are for drag racers and don't address the real problem, CV joints breaking the cage when subjected to high power at high articulation.

The only real fix is to not use all that much steering when under power! VWMS had you put a 17 or 19mm collar on each side of the rack to limit steering travel. I'm not a fan of this, it limits options, better to train your hands and right foot. A training that comes easier after experiencing the suckage of blowing an axle from being stupid. That sucks enough but it would suck more if it were to happen with an axle that cost more than most peoples' tire budget.

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Pete Remner
Cleveland, Ohio

1984 RX-7 (rallycross thing)
1978
Silence is golden, but duct tape is silver.



Edited 2 time(s). Last edit at 09/06/2016 06:27AM by Pete.

Pete;
I know it will be the CV itself, as the limiting factor, as I've dealt with CV's for my entire life. Don't think I've ever owned a RWD car, without also having an AWD or FWD in the stable at the same time. So 28 years of changing axles out to do clutch swaps, and maintenance on my own VW's and Audis.
Never actually opened one up, even though I have seen enough on the micro-fiche over the years, that I understand how they bind and break. I figured they would be a weak link, which is why I asked Leon his opinion when talking to him about springs.
However, enough guys here have brought up good points. That is so much money to spend, that doesn't make any sense. The DSS axles, are heavier duty axles, to keep them from twisting when High Hp engines transfer lots of power to sticky tires. It makes more sense to use their stuff on my Mk. 7 when I break the 400 whp barrier, than to use it on the RX car.
Because of the build time, I already had sent out both of my sets of GTi axles to be rebuilt, so I would have a set of fresh CV's and a good set of spares before my first event.

I have a simple philosophy with cars...

That's fine, I have that too, but there is a huge difference between spending and wasting. YUUGE.

Super fancy axles that will break exactly the same as $40 Rock Auto axles because they don't fix the specific problem that needs addressed, is wasteful. If you blow 4-5 axles a year while learning to drive the thing, that's a huge expense that didn't need to happen.

'Course, it's always your money, your budget, and events need filler competitors to pad out the ranks so contingency will pay full amount.

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Pete Remner
Cleveland, Ohio

1984 RX-7 (rallycross thing)
1978
Silence is golden, but duct tape is silver.