Sequential / Dog Box servicing question. RB26

[brian_s30z]

Hello All,

I really want to get a dogbox H pattern, possibly a sequential, but I've been dissuaded by the servicing of said transmissions. I contacted Samsons to enquire about a RWD dogbox for my rb26 240z, but they told me their transmission need to be checked/serviced and rebuilt rather frequently.   Their response:

"Inspection of gearbox would be needed after 600-700km. Of course there are some drivers who inspect gearbox after full season and it looks like new, while other can damage dogs after 50km."

My question to the H-pattern dog and Sequential RB cars, how often do you service/inspect and/or rebuild your transmission?  

 

[r32-25t]

I’ve got the ppg sequential and while I’ve only driven it a few times, my plan is to change the oil regularly and keep driving it unless something goes wrong like popping out of gear

[BK]

As above with the servicing, regular oil changes to keep an eye on any shedding of metal.. The most important thing to do is actually learn how to drive them, then dog wear becomes almost minimal.

I have an H pattern dog and basically have to drive around on the street like a truck - double clutch all gears and rev match. Simon Pfizer himself from PPG kept his H pattern dog in his own 32 GTR without the need to replace a single part after 20000km +, so it can definitely be done.

 

[joshuaho96]

I’m not sure how it is in Australia but in the US most long distance heavy duty freight trucks are still manual transmissions with no synchronizers. If they had to inspect the transmission internals every 600-700 km they would never be able to get their jobs done in a reasonable amount of time. It’s definitely heavily dependent on how good you are at shifting gears. If you can float gears smoothly with no drama you could probably go indefinitely with no replacement. If you’re learning on the transmission and making a lot of mistakes wear can be quite a lot and require short replacement intervals. Personally I know I’m not a pro at floating gears so I would go with synchros but if you are already double clutching every shift perfectly it’s not a far leap at that point to a dogbox. 

[BK]

On 01/05/2022 at 3:42 PM, joshuaho96 said:

I’m not sure how it is in Australia but in the US most long distance heavy duty freight trucks are still manual transmissions with no synchronizers. If they had to inspect the transmission internals every 600-700 km they would never be able to get their jobs done in a reasonable amount of time. It’s definitely heavily dependent on how good you are at shifting gears. If you can float gears smoothly with no drama you could probably go indefinitely with no replacement. If you’re learning on the transmission and making a lot of mistakes wear can be quite a lot and require short replacement intervals. Personally I know I’m not a pro at floating gears so I would go with synchros but if you are already double clutching every shift perfectly it’s not a far leap at that point to a dogbox. 

Trucks are same here - they come from the US. But yes pretty much what you said is spot on.

[Duncan]

Good on the guys at Samsonas for being honest about living with a box like that. Keep in mind they would be assuming plenty of race, not street use in that estimate.

As the guys said above, I'd change the oil annually and look for sparkles. I'd take it out for a rebuild only if I couldn't regularly get a gear.

[The Bogan]

On 01/05/2022 at 4:49 PM, BK said:

Trucks are same here - they come from the US. But yes pretty much what you said is spot on.

The gears in truck transmissions are huge, well they are in a R series Mack

We pulled a old Mack R series box to peices years ago for a look

We taught alot of people to drive in these, there was a huge amount of "cleaning the teeth in the gearbox" with the new drivers

Once they work out road speed, RPM and what gear their in, with a little rev matching and mechanical sympathy they are as quite as

Lots of fun taking off from a set of lights on a hill in a loaded Mack Dump with a trailer carrying a 15 ton bit of plant equipment

It's like tap dancing

I miss our old trucks

[BK]

On 01/05/2022 at 5:11 PM, Duncan said:

Good on the guys at Samsonas for being honest about living with a box like that. Keep in mind they would be assuming plenty of race, not street use in that estimate.

As the guys said above, I'd change the oil annually and look for sparkles. I'd take it out for a rebuild only if I couldn't regularly get a gear.

So far with dog boxes I've broken gears before dog wear has become an issue. I also used to run Quaife / Trust dog boxes frequently for years so that's not surprising.....

[brian_s30z]

Thanks all. Seems more reasonable from what you're telling me. Now time to hunt down an automatic bell

[burn4005]

having a big Neodymium magnet on the drain plug to pick up metal in the sump of the box is a good idea.

the quicker you are with your shifts the longer the dogs will last.

an air shifted sequential with shift cut/blip > manual sequential > manual H pattern as far as dog longevity goes depending on your downshifting ability.

Edited May 5, 2022 by burn4005