PROMO Guru Autowerks - ZF 6HP26/28 Transmission Adapter

martymil

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Sep 6, 2017
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Finally got the kit on mikes car, had a few hurdles to jump through with coding as it was a little different
to the USA models I guess but its all running with no errors.

Took it for a few laps around the block and the hp28 is nice and smooth and the kit is an engineering marvel.

Still need to load up the custom tcu tune as the shift points are set to low and it changes gear as its starts to build boost.

Cant wait to take it roll racing, this thing is going to hurt some ego's.
 
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135i2

Specialist
Jul 23, 2017
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135i
Finally got the kit on mikes car, had a few hurdles to jump through with coding as it was a little different
to the USA models I guess but its all running with no errors.

Took it for a few laps around the block and the hp28 is nice and smooth and the kit is an engineering marvel.

Still need to load up the custom tcu tune as the shift points are set to low and it changes gear as its starts to build boost.

Cant wait to take it roll racing, this thing is going to hurt some ego's.
Well Xmas and a bout of Covid got in the way, but the 135 ST is going really well with the Guru 6hp28 Adapter Kit.

A car ferry today back to MAD Auto Developments with Marty, and the low km 6hp28 seems to be a great choice for all the mods on the car. Feels strong and smooth thanks to the coding by Marty, hard to find a more switched on guy for our E-series.

Guru has done such a great job with this kit and if you are sitting on the fence, don't, couldn't ask for better back up and customer service despite being on the other side of the planet. Kudos Josh, thanks. Rod Stuphin has the custom tune ready to drop in after such short notice that the car was ready to start. MAD will be finalising some of the last tweaks on the car.

Advan Performance did the spanner work beautifully, big shout out to Adam and his team in Auburn, Sydney. My 6hp28 has the old 6hp21 valve body and a 6hp26 TCU from Guru. Trans was converted back to M-Shift from E-Shift so there are some scavenged parts from the 21. Guru might have some M-Shift parts to help out those that don't want to strip their 21 but not sure if he managed to get these hard to find items from ZF.

Thanks again to Josh, Adam, Marty and Rod.

Almost time to annoy V8Bait again.
 
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amjad

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Mar 6, 2022
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Greetings and congratulations on this marvel !
Any plans to extend this innovation to other Car Makers using ZF 6HP28 (Jaguar, etc.) ?
What is the torque number beyond which, this adapter would be recommended on the Stock transmission ?
 

JonEQuest

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Nov 7, 2018
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Kenner Louisiana USA
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2008 335i Convertible
RHD ZF6HP28 into the 135i ST.

Josh at Guru has been great to deal with through the whole process.
I did buy the wrong donor box so we have had to find a way forward with this local 530d unit.
A 330d would have created less of a headache but at least this puppy will hold a little more power and torque.

Having Advan Performance in Sydney install the Guru Kit around their other work.
Old box out, so you can see how tight the 3584RS is.

View attachment 62429





The 28 with a the old 21 valve body installed.
A 335d TCU supplied by Guru is also in (the black bit).

View attachment 62430




Guru Adapter on my brand new OEM 6hp21 torque converter.
Old box in the background.

View attachment 62431





335d TCU on the 21 valve body and in the 28.

View attachment 62432




Adapter only needed minor clearance work around the ST.
View attachment 62433
I thought you needed to use a HP28 TC? You said the Guru adapter bolted to the HP21 TQ?
 

JonEQuest

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Nov 7, 2018
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Kenner Louisiana USA
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2008 335i Convertible
Used a brand new hp21 converter on Mikes swap, drives like a brand new car.
OK, I thought that you had to get the HP28 TC as well. I have a fairly fresh TC. So the HP21 TC goes into the HP28 transmission? I thought it wouldn't fit because of the input shaft? I am still contemplating just doing a welded bell housing. Mainly because I have:

(1) A spare HP19/21 housing sitting on the side of my house.
(2) A spare N54 engine block sitting on a stand that I can test fit things on.
(3) A freind who is an expert welder with 20+ years experience.
 

martymil

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Sep 6, 2017
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All i'm going to say if your thinking about getting a zf6hp28 stop and get it, this kit is phenomenal.

I finally ironed the bugs out of this install and it's flawless.

The only thing I would change is the two bottom allen head bolts in the gearbox crossmember to button head bolts as they stick out to far
and vibrate against the factory alloy crossmember on heavy acceleration, it has about 5mm of clearance but it's not enough in high powered applications and sounds really bad and we thought there was something wrong with it.

I had to loosen the gearbox crossmember bolts and adjust it all the way towards the back of the car with the slack in the holes but even then its not quite enough considering how much the factory bushes flex.

Car is ready to hit the drag strip to test this gearbox out and see how it holds up, but it's as smooth as butter so far.
 
Last edited:

JonEQuest

Private
Nov 7, 2018
39
16
0
Kenner Louisiana USA
Ride
2008 335i Convertible
All i'm going to say if your thinking about getting a zf6hp28 stop and get it, this kit is phenomenal.

I finally ironed the bugs out of this install and it's flawless.

The only thing I would change is the two bottom allen head bolts in the gearbox crossmember to button head bolts as they stick out to far
and vibrate against the factory alloy crossmember on heavy acceleration, it has about 5mm of clearance but it's not enough in high powered applications and sounds really bad and we thought there was something wrong with it.

I had to loosen the gearbox crossmember bolts and adjust it all the way towards the back of the car with the slack in the holes but even then its not quite enough considering how much the factory bushes flex.

Car is ready to hit the drag strip to test this gearbox out and see how it holds up, but it's as smooth as butter so far.
I am thinking of getting it. I just have spent sooo much money already. My freind offered to put my 500 mile frictions into the dud "race" transmission I bought that had garbage in the pan. I really am too trusting sometimes. Anyway that would be a free route except fluids and my back breaking labor. I just know if it doesn't work out I am back at doing the HP28 swap. I really don't want to swap transmissions more than 1 more time and I know the HP28 is the better way to go but the cost is expensive.
All i'm going to say if your thinking about getting a zf6hp28 stop and get it, this kit is phenomenal.

I finally ironed the bugs out of this install and it's flawless.

The only thing I would change is the two bottom allen head bolts in the gearbox crossmember to button head bolts as they stick out to far
and vibrate against the factory alloy crossmember on heavy acceleration, it has about 5mm of clearance but it's not enough in high powered applications and sounds really bad and we thought there was something wrong with it.

I had to loosen the gearbox crossmember bolts and adjust it all the way towards the back of the car with the slack in the holes but even then its not quite enough considering how much the factory bushes flex.

Car is ready to hit the drag strip to test this gearbox out and see how it holds up, but it's as smooth as butter so far.
What kind of bugs did you have to iron out?
 

martymil

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Sep 6, 2017
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Down Under @ madautodevelopments
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The only issue he had with this kit was the bad vibration due to the two bottom bolts on the support bracket that was supplied with this kit which is nothing and easily swapped out with button head bolts.

The bugs where not due to the kit but modify the host of custom parts fitted to this car that needed fitnessing to make everything work and not rub or vibrate.

I still haven't changed the bolts due to the bolt supplier not being open on weekends.

We are heading to the drags this week to run some logs and put down a mph and possibly a time if traction is not an issue.
 
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