Tracsport T9 Semi Helical Gearskit Options

[PJJackson]

This year I bought a left hand drive Birkin with 5k miles on it built in 2013. It has a 2.0L Duratec, a 5-speed Type 9, and a Subaru diff. The gearbox was rebuilt by Tracsport with the semi helical gearkit.

 

I'm surprised by how much noise this transmission makes under engine braking, but not noisy at all when accelerating.  I can hear plenty of exhaust note when accelerating, but barely any when I lift my foot off the gas pedal.  I've never owned a car like this before, so I'm not sure what to expect. It's surprising to me that it would be a bad bearing since the transmission only has 5k miles on it (of course it has obviously sat for long periods of time and maybe that would allow some corrosion to occur in the bearings).

 

These transimission are supposed to be "95% quieter" than straight cut gears, but I would expect louder than stock gears.

 

Has anyone had this experience with this transmission and gearkit?

[NSXguy]

Yes “big tooth” gears will be noisier than standard gears but less noisier than straight cut gears. It’s the trade-off for the increased torque “handling” capacity. No free lunches as the saying goes... 
 

oems use helical gears(and lots of them) to give quietest, smoothest gear engagement for your normal road driving but at an expense. A bigger tooth (and fewer) is an upgrade for spirited or Motorsport, with its own noise compromise. Then straight cut for pure Motorsports/ ultimate performance but then you get all the noise. 
 

so in short, what you are experiencing is normal. You will typically hear the gears more at idle and low load. 

[Croc]

17 hours ago, PJJackson said:

 

Has anyone had this experience with this transmission and gearkit?

 

Yes your experience is exactly what I would expect and what I have heard from other owners of Tracsport T9 equipped boxes.  

 

If you are worried about internal corrosion from sitting then I think the risk is overrated as they would have been covered in grease then in an oil-rich environment.  Its hard for rust to develop that way.  I am assuming it was stored "wet", now if the box were stored "dry" then maybe you need to consider a gearbox oil change.

[oilteq]

Assuming you are using a synthetic 75W-90, you may want to try a conventional GL4 SAE 90 or 80W-90.  All three grades have to hit the same SAE 90 window at 100 degrees C, but the petroleum oils are slightly thicker at a typical 150-degree F operating temperature.  I talked several people (mostly truck drivers) into such a change, and they tell me their transmission is quieter and has a smoother shift feel.

[PJJackson]

19 minutes ago, oilteq said:

Assuming you are using a synthetic 75W-90, you may want to try a conventional GL4 SAE 90 or 80W-90.  All three grades have to hit the same SAE 90 window at 100 degrees C, but the petroleum oils are slightly thicker at a typical 150-degree F operating temperature.  I talked several people (mostly truck drivers) into such a change, and they tell me their transmission is quieter and has a smoother shift feel.

That's interesting.  I will consider that.

[7Westfield]

I run Redline MTL in my T9

[S1Steve]

This topic has inspired me to change the oil in my type 9.. Redline MLT….  Going to buy a fancy 8 dollar pump from Harbor Freight…

[IamScotticus]

I've read a lot of love for the RedLine MTL.

 

But are we sure it's the box and not the diff?

 

A 1st gear job is something I'd like to do in my T9.  Looking for kits on this side.  Any offers?

[BruceBe]

We have these particular T9s in several race cars competing in our Caterham spec-series (CC4) in the Pacific Northwest. Everyone’s ears are tuned differently, but no one has reported that sort of asymmetric noise pattern on the over-run. I’ve personally driven each of the vehicles in anger on track as well without noticing anything.

 

The previous comment about the diff is worth consideration.

 

These gearboxes have proven bulletproof over several seasons of very hard racing with, at times, some abusive gear changes.

 

We run Redline MTL.

 

cheers,

-Bruce

[PJJackson]

1 hour ago, BruceBe said:

We have these particular T9s in several race cars competing in our Caterham spec-series (CC4) in the Pacific Northwest. Everyone’s ears are tuned differently, but no one has reported that sort of asymmetric noise pattern on the over-run. I’ve personally driven each of the vehicles in anger on track as well without noticing anything.

 

The previous comment about the diff is worth consideration.

 

These gearboxes have proven bulletproof over several seasons of very hard racing with, at times, some abusive gear changes.

 

We run Redline MTL.

 

cheers,

-Bruce

I don't believe it is the diff because the sound seems to come from the footwells and not from behind the rear bulkhead, but it's possible the sound is traveling through the tunnel and tricking my ears.

 

Thank you for sharing your experience with these Tracsport gearkits.  That does make me wonder if I have a bad bearing in the box.

 

I think I will need to drive the car more and listen more closely to the location of the noise and whether the noise is there on acelleration (and just less noticalbe because it is covered by engine load and induction noise).  I just learned that the semi helical gearkit is only on 1st through 4th so it would interesting to see if the noise is there in 5th gear.   Ugh!  I was hoping to work on this during the winter, but I may need to drive it this summer to diagnose it and fix it next winter, if there really is a problem.

[IamScotticus]

 

OP (Original Poster), you may be perfectly correct in your estimate, as this is a very small car. It shouldn't be difficult to locate a noise.  But the diff is hard mounted to the frame and noise will be transmitted all through the car.

 

Noise location can be tricky.  I have a pickup that soon after new, developed what I was sure was a front end clunk.  Thats exactly where the noise came from.  Thank gawd for internet research.  It was the rear bed U bolts on the leaf springs had slackened and loosened with break-in.  It is a very common occurrence with trucks.  Internet sleuthing will reveal that on a differential, worn pinion shaft bearings and loss of preload is a common cause of the noise you are have, when you have it.

I only suggest this so you don't rule it out chasing something else.

 

OP, It would be a major pita, but can you separate the diff enough to check the pinion for float?  If this is measurable in situ,  as well as oil level and condition?

you should be able to leave the drive shaft connected.  You may be able to leave the diff attached and try sliding the shaft with your hands.  Any slack can be narrowed to u-joints or pinion end float.  Then check for pinion float.  The pinion bearing preload is something that can ease with time creating a slack that only makes noise from contact with the back side of the gears and bearings.

 

I am not a professional mechanic, just an annoying amateur.

Edited January 4 by IamScotticus

[BruceBe]

It’s also possible that the powertrain is moving slightly under the reverse loading of decel, and you’re getting some other vibratory noise related to components contacting each other (tunnel, exhaust, etc). And if it’s more pronounced at a certain rpm, something might be resonating as well.

 

Cheers,

-Bruce

[CarlB]

I have the same gearbox and have not noticed any noise off throttle, but I have to say my car is loud. If you have the aluminum case, there is a drain and fill plug. The fill plug is not accessible on a S-3 Caterham but might be on a Burkin. Change the oil and see what it looks like. I think there are other good ideas mentioned here as well. Tracsport specifically recommends The Redline oil.