Hi; I am quite new to this forum and this is my very first post. I had been thinking about swapping that 3speed TH400 with a ZF 8HP70 8 speed transmission. I did a lot of research in the web and could see that there are all the necessary adapters for this swap for SBC and BBC but nothing for BOP. Well, this is something I can handle with a Chevy => BOP adapter. Also, I could find the standalone control unit from a couple of sources. So, my final decision is to start this project ASAP. Now, I am in need of help from any of you buddies who might have done or seen this swap because I am living in Iran and having the parts purchased and shipped to me is kinda nightmare that I prefer not to experience twice. Any opinions and helps are mostly appreciated in advance. Pouria
That trannynis barely rated at a little over 500 tq handling....it doesn't take muchnon a 455 to eclipses that
8HP70 handles 520ft.lb as you said. My 74 Riv used to push out 355 when it was young. I rebuilt the motor very carefully a few months ago and it is in perfect shape now, but I am afraid it still can't beat it own performance of first day. This modern tranny has many advantages that to me the most important is 4.7:1 1st gear ratio that give a much better launch in comparison to the 2.48:1 of TH400. Also, the 8th gear is 0.67:1 that gives smoother cruise experience and much better fuel economy when compared to 1:1 of TH400. Anyway, this is now a big challenge for me and I am trying to collect the necessary parts and as much info as possible to start the project.
Looks like that is a BMW transmission. So the adapter goes from BMW to Chevy. You would need an additional adapter from Chevy to BOP? The ZF8HP70 Automatic Transmission is found in the BMW 7-Series, BMW X5 50i, BMW 5-Series , BMW 3-Series, Dodge Durango, Jaguar F-Type, Jeep Grand Cherokee, Ram 1500, Dodge Charger, Dodge Challenger, Range Rover Sport, Rolls-Royce Phantom, Maserati Quattroporte, Aston Martin Vanquish, Aston Martin Rapide and Alpina. Not sure of the dimensions, but that would be a cool swap if you can make it work. The Riviera is a heavy car. I hope it holds up. I doubt anyone here has even contemplated, let alone done what you are planning. If anything, I would think someone here would be using one of the later model GM transmissions. So, you are probably on your own. No such thing as a swap that goes smoothly without unforeseen complications. Good Luck, this should be interesting.
thats the new rams trans but why is my question? it takes a ton of adaptation. gm makes a 8l90e that would hold more power and will bolt up with 25 dollar adapter plate. both would need a stand alone but gm has alot more aftermarket support. the gear ratios are identical.
https://paceperformance.com/p-28983-gm-transmission-dimensions.html there is a spec on the gm trans out there. it doesnt have all 8l90 specs but there are slightly smaller than the 6l80 the issue you will have will be the circumference of the housing. that said if a th400 will fit it might.
Thanks everybody for your feeds. I get warm when I see replies to my post. The adapter for 8HP70 => BOP is also available for sales. 8HP70 holds BMW 750 that is little heavier than 74 Riviera. I don't think the weight is an issue for this tranny. Thanks for your wishes. I would start this challenge as soon as I found and by the right 8HP70. I investigated about both transmissions for a while and finally chose 8HP70 for a sort of reasons. The first is the availability and the price. A good working ZF can be found at around 600~800buckes while 8L90E isn't lower than 2500. Also, in Iran, there are no American cars after 90s while Germans are moving around and have many service centers. I have my own garage by the way and do the things myself, but when it comes to the spare parts, ZF is the winner in my area. Also, the ZF gear ratios are more linear than that of 8L90E specially in the first 4 gears. Also, I read some articles comparing these two transmissions and all of them voted for ZF at the end. Can't tell before having the unit in my garage, I will post here daily as soon as I start. In my recent search, I found this interesting thread in pro-touring forum where the author installed 8HP70 on small block Chevy and later on LS engine. Please have a look: https://www.pro-touring.com/threads/123590-Zf-8hp70-mated-to-sbc
The story began! I receive the 8HP70 last week. The unit is out of a 2015 Charger and seems nice: Also, I ordered the standalone TCU from HTG along with the patch PCB and received them: So, I started to open the pan, take out the valve body and mechatronics and finally to kill the original TCU inside the unit. I am not going into details of how this was done because there are many excellent videos on YouTube about this and here I am just posting photos. But, if there is any questions on any special part of the job, I would be more than happy to reply to the best of my knowledge: The first thing after removing the pan is to detach this connector: Oil pan screws: There are two sizes of screws on the valve body. Do NOT unfasten all and just stick to the bigger ones: I continue in the next post. It seems the number of the photos can't be more than 12/post.
Well, more photos below: The valve body removed The mechatronics removed And painful part of the work, the TCU cover had to be cut with a dremel and all the tiny wires had to be cut from the pins! I spent plenty of time cleaning inside the TCU housing to make sure no metal particle or remains of tiny wires are there. There is no room to risk, when the part is closed and sealed, it costs much time and energy to open and check for problems. So, do it once and do it right! Then, for more safety and piece of mind, I covered and sealed the old TCU with some thick adhesive tape and SENZOR sealing compound resistant up-to 330 degrees (Centigrade) Then, it was the right time to solder the patch PCB in place: At this point, I noticed the PCB couldn't lay down fully at its place and after some minutes of useless efforts, I decided to cut some part of the board by a cutter: And after this modification, the PCB laid down fully in place: Well, this is not going to bring me any sort of problem but I was expecting more from a 130Euro PCB! Then I started to solder and below is the result: It was time to go home or mom would go crazy I will continue next Friday (weekend in my area) and keep posting.
This is a very interesting swap. I'm subscribing to watch the progress. I'm also curious- how did a 74 Riv get to Iran? Are there lots of old American cars there?
Yes actually. The Amrican cars used to be very popular in Iran during 50s, 60s, 70s and even early 80s. After the so called revolution in 1979, the import of American cars slowed down and finally stopped. Here we had the GM assembly line for Chevy Nova, Buick Skylark and Cadillac Seville. Nowadays, there is a good number of classic cars here some of which are in excellent conditions and some under restoration in well equipped shops. I have three Buicks, 66 LeSabre (340ci), 71 GS 350 and this 74 Riviera. In case of success in swapping the transmission of Rivi, the GS will be my next project.
This is really interesting. I have often wondered what a modern 8 or 10 speed transmission would be like behind a healthy Buick 455, keeping the engine right at peak torque all the way down the track. Gotta be worth 5 tenths or more?
very cool! It takes people like you to think out of the box and try stuff. Without that, we would never know what works and what not. This tranny could be the next big thing as the older trannies are getting harder to find. Fernando
It's the heart of hot-rodding. To take something that never was and make it fit your own personal preferences. I'm curious to see how this turns out. Being as new things now do not have a BOP bellhousing, I think we are freer to explore non GM options.
Hello everybody; Thank you all for the encouraging messages. During the last week I was trying to gather as much information as possible about the project specially about 8HP mechatronics. Being one of the most modern trannies of the time, the unit is not that much complicated at all and there are some groups on FaceBook with extremely open and supporting members that leave no question unanswered for more than an hour. I believe the change will be more than one second. It is not only the gearing and ratio, but this unit is much more efficient than the old stuff and delivers the torque to the rear wheels with much less robbery in the middle of the way. It is 6% more efficient than its extremely efficient predecessor, 6HP! My expectation is to see an amazing launch with the first gear of 4.7:1 (TH400 is 2.6:1) and up-to 40% better fuel economy with the 8th gear of 0.67:1 in the highway (TH400 is 1:1). Thanks for your heartwarming message my friend. I try to do it in a way to provide full details so the next folks who decide to go the same way to do it with all the path known from the beginning. Well, having the adapter to BOP is my next challenge. The Chrysler version of the 8HP bolts on the Mopar small block with no modification. So, maybe someone has already designed the adapter to bolt a TF727 on a BOP? I keep searching. Also, a friend in Denmark made one homemade adapter to mate 8HP on his 68 Pontiac GTO (amazing project but unfortunately not too much about it on the web) and he said he may share the drawings with me.
