Which gearbox?

[mwagner10702]

For the sake of discussion let's assume I am considering replacing my stock US gearbox with either a CR dogleg box or perhaps a Tremec unit. My car is 75% HPDE track, 25% road usage which is why the dogleg box is being considered. The car may also eventually get a 2.5 or 2.7ltr engine with a desired 300hp at the flywheel so the gearbox would need to support that requirement. The replacement box should require minimal to no interior modifications if at all possible. Any modifications would need to be easily reversible. I realize other mechanical modifications may be necessary (i.e. change the diff ratio) as well.

Putting aside cost for the moment, I would appreciate your recommendations.

Thanks,
Mark

[HANDBLT]

Best upgrade I've ever done. Bar none. By far. The 3-4 shift on the US gearbox is shit. Any of the CR boxes will make the track experience so much better. I have the GrpA 5 speed gearbox and other than getting going from a stop since 1st gear is so long, the rest is glorious. 500rpm drop per gear.

My 2 cents

T

[mwagner10702]

Thank you!

[Ironhead]

I might be the lone voice here....

I prefer the stock box to the dogleg. The issue for me was the 40+ years of driving cars with first on the upper left, like the stock box, continuing to drive cars with that arrangement today, and the muscle memory that comes with it. I know it sounds petty, but trying to re-learn which gear is where...after so long...can be surprisingly difficult.

As far as the Tremec...I have a T56 Magnum in a non-BMW project car. This particular tranny handles something like 700 Lb-Ft of torque, so overkill for the E30M3, but to my tastes it shifts so much better and faster than any Getrags I have used, there is no comparison. I'm sure they have lighter-duty trannys that would be suitable for the E30M3....

[jimmy p.]

Transmissions are really the key to unlock the real fun in an S14. We dont have vanos, when we build these engines for track use no matter what displacement they have a pretty narrow power band.
Small RPM drops are the key.
The key to small RPM drops is $$$$$.
I have given this soooooo much thought. So much.

None of the 265 street options are perfect, or even really "good" for a track S14. They both fine transmissions and neither is better than the other. I have both and they both have their up and downside. Both fine for street cars and the occasional track day.

The factory Gruppe A or Samsonas 5 speed version are the ticket to ride if you want to have small RPM drops and really keep your S14 on the boil in a 265 based transmission.
The tall first gear becomes useable on track and now you actually have 5 closely spaced gears to use on track.
In both street versions first is a throwaway so you really have a 4 speed. 2nd gear is really too low to use on track except for the slowest of slow corners so you really only hav a 3 speed.
Yes you are looking at $7K entry fee for a Samsonas gear set last time I checked (and it has been a while), I think the gear set was $7K before you find someone to build it (and pay them to build it).

The real hot ticket is the Samsonas 6 speed version. But again even more $$$ AND you still need to find someone in the US to work on Getrag 265s, thats a shallow pool.

Now if you get away from the Getrag and are mechanically inclined and not afraid of adapting something else there are lots good of non BMW proper racing transmission options.
Quaife makes several transmissions that have much superior ratios and are small and light that fit in an E30 well. They have H pattern options and sequential, 5 or 6 speeds.
I think the entry level ones are still up over $5 or $6K but now you have a proper race transmission that the aftermarket supports.

I went with a G Force Road Race T5, it was a much lower cost of entry. The Tremec T5 is approximately the same size and weight as a 265, I think I paid ~$2800 for a brand new factory built, straight cut gear, dog ring trans. Now the downside is you are stuck with the ratios that GForce built for that trans and the selections are not huge.
The GForce version with the straight gears is supposed to handle 600 V8 horsepower so it will last a lifetime in an S14 powered car unless you do something stupid to it (which I have done).
1st gear is still a paddock gear but I do actually have 4 useable gears on track and if I break a dog ring its around $200 to get it fixed (at the GForce factory) If I did it myself even less.
My RPM drops are not as sexy as the Gruppe A or Samsonas options, but its less than half the cost and future maintenance is almost free in comparison to the 265 based trans options.

The real hot hot ticket is the Drenth sequential 6 speed. 6 perfectly spaced gears and never miss a shift again. Case size and weight is in the realm of the 265, I think its almost a bolt in.
Last time I checked I think thats around a ~$10k project but wow is it perfect.

Transmissions are a deep subject, there are WAY more options, it really comes down to (a) how much you want to spend and (b) your tolerance / ability to adapt and develop a non BMW option.
I could literally keep writing about this subject for hours but I think you can get the basics from the above.

Cheers
Jimmy p

[mwagner10702]

Thanks Jimmy. Really appreciate your thoughts here.

[Ironhead]

"Clunk" (mike drop). Nothing more needs to be said. Well done Jimmy.

I just wanted to add....with the tracks I visit...the 265 is a two speed trans. I never use 5th, only very rarely use 2nd.

[1990m3]

I have a Samsonas and it's awesome on track but I'd never want it on a street car. The gear whine alone increases interior volume about 100% and is now the loudest thing I hear in the car. I drove it to my friends shop for alignment and it was miserable (I didn't wear ear plugs).

Prior I ran a US gearbox with a 4.45 diff and was very happy with it. I'd run that again in a heatbeat.

[Anri]

Hi,

The US 5spd 265 has exact same ratios as Getrag 260. The gear box is nice for street driving and quick take off the line but that is it. In fact the Getrag 260 is little lighter than the Getrag 265 which is welcomed. The G260 came on all M30 big block engined cars which will be direct fit to out S14 block.

G260/G265 ratios are 1st 3.83 2nd 2.20 3rd 1.40 4th 1:1 5th 0.81

Dog-Box. 1st 3.72 2nd 2.40 3rd 1.77 4th 1.26 5th 1:1

Dog-Box is much better option compare to 265/260 for those who are after hi performance and cams, and box, and much better on the track which keeps the Rev up top with less rpm drop and also gives you the freedom to use various differentials for specific tracks.


Anytime one has a gear box which uses a Clutch on shifting the calculation should be to minimize shifting and to have as little rpm drop as possible and the Dog Box does exactly that (Till today I have not found replacement on Dog-Box being better option and I looked at Zillion boxes, just none). One can collect a data form its home track and apply. Less shifting is better on Clutch type. More shifting is better if one choses a Flat-Shift type of boxes like Samsonas then we have gains because one can use all the gears and accelerate the engine without the loss of physical clutch type which it has its losses.


A properly geared engine for a specific track is like adding 100hp to your engine and even more...

I made a calculator so I can calculate the speed at the specific track what my engine accelerates based on data I have collected for the specific track etc.

By far no box can beat the Dog-Leg for using a Clutch type shifting because the gear ratios are very good its very light at 87 pounds (I scaled it about 10 years ago but forgot the exact #)

Bellow I applied the Data in comparison on the G265/G260 vs. Dog-Box.

If anybody has a specific gear box which wants me apply the data just post the ratios and we can compare.

Note how to read the data: Say you chose 8000rpm on any gear then on 2nd look at the graph and search for the same mph. Say 1st gear is 46mph at 8000, 2nd same mph 5100rpm. 8000-5100rpm is 3400rpm drop.

jimmy p. The price is around $5500 what extra work or parts have you calculated so that it jumped to 10k ?


Regards,
Anri

[jimmy p.]

@First E30 M3
Anri - not sure you read my whole post, but If you can get Drenth sequentials for $5500 I'll take two tomorrow. Let me know where to send the money and I'll send you my shipping address.

https://racecarsdirect.com/Advert/Details/99764/drenth-dg400-sequential-gearbox-400nm500nm

Regarding the Samsonas 265 optionI just checked on VAC's site the Samsonas gear set is now $6K USD (+ someone to build it) I had not checked in a while, probably should have.
So my post was off ~$1ooo on the Samsonas option.

[Anri]

@First E30 M3
Anri - not sure you read my whole post, but If you can get Drenth sequentials for $5500 I'll take two tomorrow. Let me know where to send the money and I'll send you my shipping address.

https://racecarsdirect.com/Advert/De...box-400nm500nm



Regarding the Samsonas 265 optionI just checked on VAC's site the Samsonas gear set is now $6K USD (+ someone to build it) I had not checked in a while, probably should have.
So my post was off ~$1ooo on the Samsonas option.

Jimmy,

I am sorry for not making a note, I was referring for Samsonas not Drenth. Drenth is more money indeed. About a year ago I sow the 265 Samsonas Kit which is slight cheaper than Gr.A. and the ratios are virtually same with micro chances which are neglected.

Okay so price went to 6k plus shipping, honestly its not too bad. I also can put it together.

I am tiny bit happier with the Samsonas ratios vs Drenth.

Regards,
Anri

[RGNLM3]

If you have other cars with a normal H-pattern manual, you may not want to have a dog-leg in the mix. Might cause more mis-shifts.

[jimmy p.]

If you have other cars with a normal H-pattern manual, you may not want to have a dog-leg in the mix. Might cause more mis-shifts.

LOL Long ago when I first got the Gruppe A car I had an OD box in my club racer and the Gruppe A box in the Gruppe A car (which is a dogleg first) I used to have a piece of gaffer tape on the dashboard of the Gruppe A car with the shift pattern as a reminder.

[jimmy p.]

I The gear whine alone increases interior volume about 100% and is now the loudest thing I hear in the car. I drove it to my friends shop for alignment and it was miserable (I didn't wear ear plugs).

OMG the gear whine is almost (and I said almost) the best part. Its intoxicating LOL. I sometimes think I race to hear the gearbox LOL (although I have worked in the live music biz for 37 years so I could possibly be a little deaf.

[1990m3]

OMG the gear whine is almost (and I said almost) the best part. Its intoxicating LOL. I sometimes think I race to hear the gearbox LOL (although I have worked in the live music biz for 37 years so I could possibly be a little deaf.

Yes -- on the track. On the street though it's not great!

[craz azn]

If you already have a US spec gearbox installed, I would just pair it with a super short diff, and enjoy. I have a eurospec car with a dogleg, and the gear ratio spread between 3rd to 4th gear drives me insane. In my opinion, it is not worth the cost to change from an overdrive US gearbox to a dogleg, plus still have the required diff ratio change costs involved.

That said, I will echo what the others have said, and point out that the car comes alive with a transmission that utilizes a race gear ratio spread. Unfortunately, almost every option in this arena is very pricey, and probably unlikely to be a bolt in solution.

FWIW, I'm looking to put a Group A gearset into my spare 265/5 and hopefully that should satisfy my gear ratio woes.

[idickers]

One intriguing option is the Mazda RX8 6-speed. I guy over on the 2002FAQ made an adapter plate. The RX8 boxes come with some interesting gearing. There are two variants, the S1 and the S2, and in the attached pic they are compared to the Getrag 245 boxes that are often used in the 2002, the overdrive 245 and the unobtanium 245 close ratio.