CaribbeanPirate

I was thinking about it as im using them in the Buggy, if anyone has, let us know how it goes!

Paper2

Hello CaribbeanPirate, the engine is the Reds R5T Team Edition GT

Hotspur

Anyone run the the 13/44 in both diffs? Or usually just the rear?

thommi

GT class rules do not allow for having under-/overdrive. Both front and rear need to have the same diff gearing. With that, the gearing ratios are an adjustment to make depending on the track layout.

British Menace

Yes. I have ran that configuration in my diff's.
I found it good for the big tracks but too much was lost, for me out of the slower corner's.

Having said that ..... My clutch was not the best in the world. Good but not great. Going to a Buku clutch may give you what you need out of the slower corner's using 13/44 diff's.

Regards
BM

Scott B

iTrader: (47)

What rule book states no under or overdrive?? I didn't find anything in the Roar rules..

Hotspur

Yes that is what i am experiencing. Coming out of slower corners. I was running 12/42 front and 13/44 rear before. Lap times were better but the back came around a lot. It seemed to have settled it down. Our straight is about 200ft. Would 12/42 front and back not be enough?

thommi

I have found an IFMAR draft here... http://www.efra.ws/wp-content/upload...compressed.pdf

it says:

No center differential allowed. Ball differentials not allowed/only gear differentials. Front and Rear differential gear ratios must be identical. Front or rear underdrive or overdrive is not permitted. The final drive ratio front and rear must be the same.

thommi

Two things... has anybody tried the Buku clutch with the Mugen bell? Does it fit? Mugen bells are a bit smaller than regular clutch bells, having an inner diameter of 26mm compared to the usual 26,5mm.

About the rear end coming around, go heavy on front diff oil, but real low on rear. depending on track conditions, I run 1 million front, 10k rear (low/medium grip), and 500k front, max 30k rear on high grip.

Scott B

iTrader: (47)

edit... Just went thru the roar webpage a bit more and found basically a copy of the ifmar rules so over/under drive is not legal under roar rules either.

Thought about trying it before but I've always gotten the car to work with the 13/44 gears frt/rear so never did try it, good thing I didn't.

Scott B

iTrader: (47)

I've been running the buku, works good. I played with turning the set screws in a little at a time but seems best to just tighten them in all the way and back them out about a half turn or so but that will depend on the motor as that was great on my picco but still felt sluggish on my mito. And this was with the std buku Gt shoes, I have the lightweight versions still to try.

Interesting you run so thin in the rear, I've been running 2.5 or 1mil front and 150k rear and don't have issues with loosing the rear end.

British Menace

Yes. The BUKU clutch fit's fine. I have not ran it yet though.

I would run 12/44t diff's. 15/21 Pinion's and 50/45 (or 44t if you have it) spur gears. At 200ft you will top out around 3/4 of the way down the straightaway but that shouldn't make a lot of difference to your lap time. Where you will gain is in acceleration and middle rev's.
The only time you could suffer with this is if you run an off-road engine. (lot's of bottom end but wont rev out top end)

As far as the rear end grip.
I have ran most set up idea's as far as oil's from 2.5Mill to 500K Front and 50K to 300K rear. With varying success. The high front diff oil's do make the car easier to drive and can be very fast especially if you have been able to cut the caster down on the front end to improve the car's turn in.
The rear seam's more a personal choice. My car still turned in well with 300K rear oil just as it did with 50K oil?? I have ran these both on low and higher grip tracks too. So I would leave your rear diff' and fine tune with oil once your happier with the rest of the rear acting as you like.
Use a middle of the road oil, say, 75K oil just for now.
(I have even heard of some using 500K oil in the rear in low traction circumstance's!)

What I would do is put your rear toe to max using the insert;s and your anti-squat to max also.(Front pin holder high, rear low) and don't go too soft on the rear spring's! You need the mechanical grip from the harder spring's, especially if you run the car low (Ride height)
Keep you top rear arm's short and steep too and put some angle to your rear shocks. This will give you some advance warning of the rear end sliding out. (This will also make the rear spring's feel softer to the car hence you needing to go to a harder rear spring - Blue or white!)
2.5 to 3 degrees of rear camber too.

Hopefully this all help's. Sorry for the long post. I get carried away some times :-)

Regards
BM

Hotspur

Did you mean 12/42 the stock gearing or run 12/44? I'm using a top elite 5 modified from The nitro shop for GT. I use the rcshox pistons with 1,000 oil and the black springs? Do you think the springs are to soft and causing some of the problems? Thanks for all the help .

thommi

We tried out a lot of things, shocks oils, pistons, springs, shock positions... but what makes most difference is the diff setup. While with a lower real oil you might not make the absolute fastest laptime, you will be ways more consistent, and this is what wins the races. GT class is about very small differences, and being consistent is key. I did use oils like 1 million front, 500k rear, but try it out once, go to 30 or so in the rear and tell us about it on here after it... In order of what you should work on in the GT class, I would say diff setup first, then clutch (right clutch with right settings), then body. If you got a good engine (get yourself a WERKS GT) and you got these three settings right, you should be all set.

British Menace

You can try the 42/12 to start if you like. I have gone to the 44/12 set up because of the acceleration gain's.
I would definitely go to harder spring's. Especially if your track has a decent amount of grip.
Try Mugen blue all round or even Mugen White's all round.

Once you've done this and the rear lower suspension pin placement and camber's. You can start looking at diff oils.

Try different oils but try to remember these few point's.
Always try to put the same amount of oil in each time you fill.
Check for leaks each time and make sure your outdrives and drive pin's/ shafts are in good mechanical shape!

Choose a front oil, say 1Mill, if that's what you've been running, and stick with that for now and concentrate on the rear.

When choosing rear oil. Go real thin to start. You need to watch the car at corner entry, when off power or braking. The car will probably be a little loose (over steering) with the very thin oil. Don't worry too much about mid or corner exit for now. Just corner entry.
If the car is loose at entry. You need to go thicker on the oil. Keep doing this until your corner entry is stable and you like the feel of the rear of the car going in.
Now go to the front diff. Thicker your front diff, = less turn in Thinner front oil = better turn in.
Again. Concentrate on corner entry first.

When you get the front how you like your entry and the rear is still stable. Your getting close....... :-) You'll be able to go thicker all round if traction is high.

Remember. With the rear diff. Thicker oil will give you over steer at corner exit. Too thin will give you over steer at corner entry. :-)

Hope this help's. Sound's as though you have a really good engine so you may be able to pull 44/12 down your main straight but if your engine and clutch can pull the slower corners with 42/12? .... go with that.

Also. There are many ways to go about setting up a car, especially where diff's are concerned. I have just pointed one way of doing it.

Good luck.

Regards
BM