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Thread: My 8HP70 swap.
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10-14-2020 #1Registered User
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- Jan 2020
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- Sweden
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My 8HP70 swap.
Hi, Håkan from Sweden here. Now that i have finished im doing a thread of my swap.
This is the car i made the swap in, 1965 Dodge Coronet 440 with a mild 512cui engine and Holley sniper.
I have a very slow going pro touring project in the garage, same car as above:
I have been wanting to replace the old leaky 727 for an overdrive transmission a long time and in january or so i first heard of successful swaps in Poland of the 8HP70 using the https://htg-tuning.com/ GCU.
This seemed like a good solution since it replaces the stock ECU in the transmission and fully controls it.
So, i started researching and at the time i only knew the 8HP70 could be found in Dodges and BMW´s and since the Dodge ones is very expensive in Europe i went with a BMW (i didnt find any measurments of the bellhousing so i had to estimate from pictures if it was likely to fit).
I got one from a BMW F10 2014 but as soon as i got it home it was clear that the bolt pattern was way to small.
So, after that i did more research and found out the 8HP70 was in a lot of different cars and found a Jaguar XF 2.2D wich looked right in size.
This one was spot on in size, so now i had to fabricate an adapterplate. I found a blueprint of the 727 bigblock bellhousing so i could get the measurments of the engine side from that minus the holes for the starter.
As for the transmission i first tried a method i saw online using a lexan plate secured o the transmission and then using guides in the holes drill thru the lexan to get the hole positions, i then had the guys in the measuring department at work run it in a Zeiss measuring machine. I then double checked the distances between the guide pin holes on the transmission vs the measured and it turned out this method wasnt exact enough.
So i brought the transmission to a company and had them measure it properly, both the bellhousing and the output shaft flange.
(To be continued, got to go to work).
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10-15-2020 #2Registered User
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- Jan 2020
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- Sweden
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I got very precise measurments so i then used Solidworks to make a model of the adapter, since the Jaguar 8HP70 has the torque converter sticking out a bit from the bellhousing i needed to make a quite thick plate.
In conjunction with this i had to get a flexplate with ring gear for the starter since the torque converter doesnt have one. I decided to use one from ATI: ATI915650X used to put GM transmissions on Mopar bigblocks.
Ill write all measurments in millimeters since thats what i use and i dont want to accidently miscalculate to inches and cause confusion.
When i calculated the thickness of the flexplate and how much the torque converter was sticking out plus the needed play in-out of the transmission i ended up with a 35 mm plate.
The flexplate is used with a crank adapter so the center hole is bigger then the crank pilot so i had to make an adapter for this. It adds 2 mm behind the flexplate and centers it.
Also the pilot on the torque converter needs an adapter since its much smaller than the original one, seen in the picture above.
Check to see it mounts straight. I used ARP 200-2902 bolts for the flexplate.
All good
Next was making new holes in the flexplate for the torque converter bolts, made on the Deckel mill.
Fits like a glove (you can see the flexplate adapter here also)
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10-15-2020 #3Registered User
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- Jan 2020
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- Sweden
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All this took a long time since i had to finish one step before i could do the next.
Got the adapter plate from gas cutting, this is steel since the weight isnt important on this car, its cheaper and i can weld the dowel pins on.
Time to make the holes on the bigger mill at my brothers work. Its made in one setup and the holes for the dowel pins are drilled and reamed straight through to avoid having to flip it over.
I finished drilling and making threads at home.
Testfitting with dowelpins, fits very snug (i later read that 3 pins isnt necessary and you an skip the top one).
Engine and transmission mounted
Did a test with an indicator gauge on the flexplate and measuring to the input shaft on the transmission, about 0,23 mm total runout.
https://youtu.be/O_AQvlQgR6E
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10-17-2020 #4Registered User
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- Jan 2020
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- Sweden
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I had to make connectors for the oil inlet and outlet, i used AN6 because the biggest oilcooler i could find at the speedshop had those connectors.
Next was fitting the starter. Since i didnt have any measurments for this i made a plate with welded bolts that fit to the starter and then i aligned it to the starter ring with a nice gap. I then welded the plate to the adapter and made shims to align it in the length axis.
The Jaguar 8HP70 i use have a similar output axle flange as the Dodges but it is a bit smaller so i had to make an adapter for it also.
I used the Spicer 3-2-119 Flange Yoke for 1350 universal joints and had a company CNC cut the adapter, i made the threads myself.
I used 12.9 grade M10 allen head bolts to fasten it to the flange.
And ARP 200-2807 for the yoke.
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10-17-2020 #5Registered User
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- Jan 2020
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- Sweden
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Now it was time to modify the transmission so the GCU can control it, HTG-tuning have made an instruction wich can be found here:
https://drive.google.com/file/d/1vMy...FeSe-BnD6/view
Unfortunately when i did my soldering the instruction said to use thinner wire and they found out later that 17awg, 1mm2 was needed to drive the solenoids so i had to redo some of the cables as seen in the picture.
I used Permatex grey to secure the cables.
On these transmissions the oil filter is integrated in the oilpan, one for the Jaguar was about 110$ or so but since i had heard that all 8HP70´s should be the same in this area i bought a cheap one for a BMW instead at 35$. It fit but one bolt in a corner was a bit tricky to get in, i think it was because of cheap product and not a difference in bolt pattern. And with this in the car for the first time in like 20 years it is not leaking transmission fluid!
Here is a pic with the oilpan off and the torque converter attached to the flexplate, Bolts are 12.9 grade M10 allen head. The procedure to remove the mechatronic unit is kinda easy. The tricky part was to split the plastic cover to expose the ECU, you have to grind off 2 "knobs" on the plastic to separete the 2 halves. Unfortunately i dont have any pics of this.
When you are done with the soldering and have assembled the mechatronic unit again but before you put the oilpan on you should do a valvetest to see that the soldering is correct. See the testing part on htg-tuning.com FAQ section. Here is my result (poor pic):
Time to see how it fits in the car, since i have my project car in a rotisserie i put the engineblock and transmission on a lifting table and rolled it under to see how much i need to cut out of the tunnel.
The clearance was decent but it was hitting the transmission crossmember, the 8HP70 is much bigger in this area than the 727. I cut out part of the crossmember.
Now i could get it to where it should be but it was very close to the tunnel so i decided to cut it all out and make a new one plus a new inverted crossmember.
Later it turned out i should have made the crossmember a bit higher to allow the transmission to be raised a bit more for better driveline angles, it works for now though.
New transmission mount needed, i could use the outer holes in the transmission crossmember and drilled 2 new ones in new location. I used a Energy Suspension Transmission Mounts 3.1108G and welded up the frame (not the best pictures).
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10-17-2020 #6