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Nissan L28 to GM/Olds Adapter Plate


240Z Turbo

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Well, although I drilled the 280zxt bellhousing for the C4 it turns out I will have to use the Maxima bellhousing because it is bigger. There is no stock app converter for a C4 that fits into the 280zxt bell. I may still do the C4 swap, but have sent out my bellhousing and nissan pattern plate to a company to make the adapter plate to mate the GM/Olds tranny to the nissan L28 engine. I sent the stuff out today so I will be next week before he gives me a quote on how much. It should be under $200/per for the initial 2 plates I am having made. Will keep you updated. If the height differences for the flexplate/converter are not too far off I have found a company that will also make a custom flexplate(non-SFI) so this is a boltup affair. I will also need to determine what application OEM glide converter I want to use. This will keep the costs down for a converter.

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I'm going to hang on to the maxima tranny for a while and see how my rebuilt tranny holds up. I will probably use it myself down the road. Unless you want to trade me for a certain abused 4sp auto that has lead a tough life in a twin turbo 240. :wink: After the swap is completed of course.

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UPDATE:

The company received the plate and bellhousing yesterday. Preliminary layup shows an overlap with the starter and dowel locator for the powerglide tranny. We believe we have an easy fix for this. Take one of the other bolt holes as a locator point using a bushing so a bolt can still be passed through the hole. The company said they would let me know something by Thursday. I will keep you updated.

BTW: The plate will be made from 1/2" aluminum.

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UPDATE:

Plate is a go and will cost about $300. Gear reduction type starter must be used as it does not have the snout that extends into the bellhousing. This allows the hole in the plate for the starter to be much smaller allowing enough material for the tranny dowel pin to be used. It was slighty overlaping the stock starter hole. I am shipping them the raw material to save some cost and it should be ready by Friday next week. I will post pics.

Nah, nah, nah, nah, nah...nah, I'm gonna have a powerglide :twisted:

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I guess it won't be a street car anymore, at least highway driving. 2 speed on the highway, ick. :shock:

The highway gearing will be no different than stock in 1973. The glide ratio in 2nd gear is 1:1 as was the stock 240z tranny in 4th gear, also 1:1. I admit OD is nice, but how often do I drive the car on long trips? That damn plastic seat hurts my ass :P

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  • 2 weeks later...
Guest nikko74z

My partner and I have had a turbo 350 for 2 years behind a stroker I6 with 14:1 compression. We use a ford 8.8 rear pumpkin. The tranny has a trans break and we launch at around 3200 rpm. We have been having a problem with the datsun flywheel. It keeps breaking. The plate was milled flat after cutting it out. The converter is straight and there is no vibration when I run it through the gears. The flexplate breaks in a circle where the bolts attach it to the back of the crank. Its a perfect circle the size of the crank. It looks like a donut. We have gone through 3 flexplates since we put the thing together. It runs in the 12's on motor, but the goal was to shoot 225 nos shot as well. If the damm thing breaks flex plates on the motor alone. The nos is out of the question. My theory is that some where, something is not flat and straight. It all comes apart this week-end. The converter goes back to the shop. The adaptor will be checked and the transmission will be coming apart to see if there is any wear on the pump and to make sure the bell housing is straight. I was even considering setting up the tranmission mount with a rubber insolator. Right now, its solid and I do not know if this poses a problem. At the moment, the 200 tranny has better gearing than the 350 for our application. All in all its been a headache, by we just got sick of trashing the 4 speed when you missed 2nd gear.

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Nikko, I have run over 10 mid-low 11 second passes with the stock maxima flexplate. However, I am not leaving with a transbrake. My new adapters scheme does not use the nissan flexplate to transfer power, only to work with the stock starter. Spaced about 1/2" off the nissan flexplate is a custom HD flexplate that has no ring gear and has been cut down. So, the stock GM converter is bolted to a HD flexplate attached to the crank. I have finished the adapter plate for the 2nd flexplate and all bolts up with the proper clearances. I am currently trying to locate some specific bolts M12x1.25 to bolt this adapter to the crank. It is a tight fit, but it should work. I may have these made from 4140HT in the future as I am suspect to the T6061's ability to withstand the abuse.

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nikko74z >>> My partner and I have had a turbo 350 for 2 years behind a stroker I6 with 14:1 compression. We use a ford 8.8 rear pumpkin.

 

Sounds like a nice set up. Is there any way to see some pics of this install ????

 

Thanks

joel

 

I second that. I would be nice to have some gearing options with the ford rearend.

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UPDATE:

Here is a pic of the prototype adapter for the 2nd flexplate(GM HD). The raised portion in the middle centers the pilot for the GM converter and also centers the GM HD flexplate. The inner 6 holes go to the nissan crank while the outer 6 holes are for the GM HD flexplate.

adapter1.JPG

adapter2.JPG

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