[Geighty7]

Let’s hear some opinions.

Pros/cons of engine braking during break in. Would love to hear from both ZF8 and 6MT owners.

This is my second G87 and I’m getting ready for another break in process.

I am rocking a 6MT looking to really settle that clutch in nice during this pivotal first 300 miles paired with a nice brake run-in. Likely super easy on the clutch (this means slipping a bit more than I’d normally drive).

Still on the fence if I introduce sub 4k engine braking or throw it into neutral during the first 600 miles when slowing.

[Bumpinjeep]

There's multiple threads on this. I would just search and comment there if needed.

[meechy6ix0]

Originally Posted by M2siast

It’s important to engine brake and not throw it into neutral. It’ll help with engine break-in.

However, I don’t recommend lowering gears to reduce the speed of the cars, ever. That’s what the brakes are for. But don’t ever put it in neutral (unless you’re already below 20km/h and coming to a stop).

Running in neutral means idling. It’s important to idle as little as possible, especially during break-in.

This for the ZF Manual.

For the ZF auto:

NEVER EVER EVER EVER throw the car in neutral while driving, and avoid throwing it in neutral after stopping. Just leave it in drive if you’ll resume driving, or put it in park if parking it.

don’t have an auto, but why don’t put it in neutral?

[Geighty7]

Originally Posted by M2siast

It’s important to engine brake and not throw it into neutral. It’ll help with engine break-in.

However, I don’t recommend lowering gears to reduce the speed of the cars, ever. That’s what the brakes are for. But don’t ever put it in neutral (unless you’re already below 20km/h and coming to a stop).

Running in neutral means idling. It’s important to idle as little as possible, especially during break-in.

This for the ZF Manual.

For the ZF auto:

NEVER EVER EVER EVER throw the car in neutral while driving, and avoid throwing it in neutral after stopping. Just leave it in drive if you’ll resume driving, or put it in park if parking it.

What’s your opinion on the clutch engagement in the first 300 miles while it’s breaking in?

[two_three_two]

Originally Posted by Geighty7

What’s your opinion on the clutch engagement in the first 300 miles while it’s breaking in?

i personally felt a huge difference in my clutch from 0 miles to 2k miles (now at 3k). first 300-400 miles i granny drove until warm, and never topped 4.5k rpm. after that until break in i still granny drove it until warm but once warm wasnt shy about running to 5k rpm. post break in i am driving normally until warm and then holding nothing back once warm

FWIW i still havent launched the car.

[RockCrusher]

Originally Posted by Geighty7

Let’s hear some opinions.

Pros/cons of engine braking during break in. Would love to hear from both ZF8 and 6MT owners.

This is my second G87 and I’m getting ready for another break in process.

I am rocking a 6MT looking to really settle that clutch in nice during this pivotal first 300 miles paired with a nice brake run-in. Likely super easy on the clutch (this means slipping a bit more than I’d normally drive).

Still on the fence if I introduce sub 4k engine braking or throw it into neutral during the first 600 miles when slowing.

Super easy on the clutch does *not* involve slipping the clutch more.

Doesn't take much engine RPMs and clutch slippage to get the car moving from a dead stop. That's all one should use. Just enough engine RPMs and clutch slippage but no more.

Rather than type all of this in I'll just paste it...

Break-in procedure

Engine, transmission, and axle drive

Up to 600 miles/1,000 km

Drive at varying engine and road speeds, but do not exceed 5000 rpm and 106 mph/170 km/h.

Avoid full throttle or kickdown under all circumstances.


From 600 miles/1,000 km to 1,200 miles/2,000 km

Drive at varying engine and road speeds, but do not exceed 6000 rpm and 130 mph/210 km/h.

Avoid full load in gears 1 to 3.


At 1,200 miles/2,000 km

Have break-in service maintenance performed.


As you drive the car sub 4K RPMs engine braking is going to happen unless you take extraordinary steps to avoid it. Which you shouldn't do.

With either a manual or automatic transmission whenever possible I rely upon engine braking to slow the car. There is more with a manual to be sure.

But I don't downshift to slow the car. I downshift when engine RPMs have come down -- from the vehicle's speed decreasing -- to a pretty low RPM. Downshifting at lower RPMs to reduce wear and tear on the synchros and clutch. Now with the M2 this wear and tear is alleviated to some extent by the rev matching that is done on a downshift.

Still old habits die hard. Even though I could downshift at much higher RPMs when slowing the car there is no real need to. Any braking necessary will be obtained from the brakes. That's what they are for.

The vehicle can slow quite a bit even in a higher gear before engine RPMs decrease to too low a level. When the speed gets low and the engine RPMs get down to around 1K I'll shift into neutral -- depending upon the circumstances I may have at some point while the car is slowing downshifted to a lower gear so it is not like the car has coasted all the time while in say 6th gear -- while using the brakes to slow the car further and bring the car to a stop.

That is if I'm on the freeway and take an exit exit ramp length permitting I'll let the vehicle shed speed while in 6th gear then as the vehicle speed decreases I will down shift to a lower gear -- 4th gear -- and let the vehicle shed more speed. As engine RPMs drop to some point I'll shift to neutral then brake the car to a stop.

On city streets chances are the transmission is *not* in 6th gear but in 5th, 4th or possibly 3rd gear.

(As an aside and as a general rule for cruising at the posted speed I use 2nd in 25mph zones, 3rd in 35mph zones, 4th in 45mph zones, 5th in 55mph zones and 6th for higher speed limit zones.)

For a stop I let engine braking do its thing and just let the car slow to the point engine RPMs are low enough that a downshift (or a shift into neutral) is called for.

Thus by using just engine braking to scrub the speed off the car without downshifting and then as the car's speed gets to the point a down shift is becoming necessary shifting to neutral and applying the brakes reduces wear and tear on the clutch, transmission, and brakes.

This technique has worked well for me over the years. I have driven a number of cars equipped with manual transmissions to 150K miles and beyond with no excessive clutch wear. (In the case of my '96 Mustang GT the throw out bearing went bad at ~150K miles. Clutch was still ok but I just had both the throw out bearing and clutch hardware renewed.) (Now with the case of my Boxster at 317K miles on the original clutch while the clutch was not slipping nor manifesting any other signs of trouble the effort it took to work the clutch pedal signaled the clutch was worn out and due for replacement.)

Oh, for automatics for slowing down with time permitting I let off the gas and let whatever engine braking there is reduce vehicle speed.

Trouble is the engine braking effect with an automatic transmission is less than what a manual transmission provides. But I don't downshift the automatic to slow the car. I rely on the brakes to slow the car. (As my auto tech buddies told me years ago brakes are cheaper to renew than clutches/transmissions.)

In short there is no need for you to over think this. Really just adhering the break in guidelines as you drive the car the engine will be treated to a mix of various throttle openings/engine loads/RPMs and break in will proceed on schedule. Far and away the vast majority of any break in occurs with the engine under some load. There is no need for you to avoid or increase the amount of engine braking time. Whatever engine braking that occurs operating the vehicle in accordance with break in guidelines and in accordance with safe and legal vehicle operation is fine.