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Post by pmd400 on Oct 5, 2022 21:01:20 GMT
Hi
Has anyone ever put a later model 4 speed overdrive auto trans behind a 3 litre? Is the 3 litre bellhousing pattern an sae pattern?
Josh
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Post by eightofthem (Andy) on Oct 6, 2022 18:48:42 GMT
Welcome to the forum Josh.
It's perfectly do able.
The ZF has been transplanted into the P5B, so no problem with the actual fit.
Your issue will be the connection between the engine and transmission.
I have a solution that I am working on to resolve that.
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Post by pmd400 on Oct 7, 2022 0:25:25 GMT
Have you got anymore info you are willing to share? I’m guessing the mark 3 drive plate and ring gear with be required for the swap. There is a company in the states that make sae to chevy trans adapters. The rover 3 litre looks to be a round 12 stud bellhousing pattern like an sae.
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Post by eightofthem (Andy) on Oct 7, 2022 12:47:06 GMT
Hi Josh.
Yes for sure, before we gallop along too far, what do you have at the moment Mk11 or MK3 ? Is it auto already or manual ? DG or BW box ?
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Post by MK IA Norway Viking on Oct 7, 2022 12:53:13 GMT
Good afternoon,
I like to enter this thread. I have a MK IA with 4 speed manual box.
I have just ordered an overdrive and will be fitting it before next driving season. I will need to obtain an itermediate drive-shaft that fits, for the one presently installed will be too long when the overdrive is fitted behind the gearbox.
The solution you work on Josh, will that include an intermediate shaft that will fit the new setup on my car ?
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Post by enigmas on Oct 7, 2022 22:42:23 GMT
You may have misunderstood the context of the modification being discussed Norway Viking. The modification under consideration is that of fitting a modern 4 speed automatic overdrive (not a period/factory manual overdrive trans) behind a P5 3 litre 6 cylinder engine.
The considerations for this type of modification are quite different than for adapting a manual trans.
A few technical considerations are:
A suitable flexplate, flexplate adaptor or flexplate modification that allows the P5 3 litre starter motor to engage correctly.
A bellhousing or bellhousing adaptor that couples up to the 3 litre engine and also allows for the correct backspacing of the torque convertor when fitted up to the transmissions pump.
A spigot engagement hole for the engine side of the torque convertor when it bolts up to the flexplate. The flexplate (hence its name) allows for slight movement of the torque convertor back and forth under torque loading and heat cycling when the vehicle is being driven.
Another consideration more so on a well worn engine is crankshaft movement via well worn thrust bearings. Axially crankshaft movement (fore and aft) needs to be taken into account with regard to torque convertor backspacing. This is to safeguard the transmission pump when the torque convertor moves back and forth slightly during normal operational use.
These are the considerations I needed to evaluate when adapting a ZF4HP22 automatic from a Jaguar to a P76 V8. Some components will need to be custom fabricated.
Good luck with your project.
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Post by pmd400 on Oct 9, 2022 10:45:39 GMT
Mk ii, auto, DG gearbox
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latecomer
Rover Rookie
Always expect the unexpected
Posts: 9 
Location: Yorkshire
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Post by latecomer on Oct 10, 2022 9:58:53 GMT
Andy,
Hello. Trust all is well with you.
I have a 1967 P5 mkIII coupe with BW 3 speed auto box that I would like to uprate to a ZF4. It would be much appreciated if you could keep me in the loop with regards your upcoming resolution.
Regards,
Stuart
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Post by eightofthem (Andy) on Oct 10, 2022 21:13:43 GMT
It would be easirer for the conversion if you have a BW35 rather than the DG.
That said it can still be achieved either way.
Stuart, will do 👍🏻
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Post by enigmas on Oct 10, 2022 22:44:32 GMT
Looking forward to seeing the development of this conversion. This is one complex project!
I'm envisaging lots of custom fabricated pieces, including:
A modified bell housing and or bell housing adaptor,
A custom flex plate, and
A rear spigot bush centralizing adaptor for the ZF torque convertor
All these components will need to be carefully engineered to ensure proper alignment and torque convertor setback within the transmission. Any newly engineered and/or altered rotating pieces will also need to be rebalanced as these items tack onto the end of the crankshaft. Any slight runout will cause a severe imbalance situation. Been there myself on my MG Magnette project.
This is one hell of a project and a very costly as a one off conversion, but good luck to you Andy and all kudos to you if you manage it.
As an aside a simpler solution on a MK3 P5 is to adapt John (Wallet's) laycock electric overdrive unit to the rear of the BW35 of the MK3 as John did on his immaculate P5B. Then drop the differential ratio to 3.7:1 (from the existing 3.5:1) This would provide both an overdrive and a faster more responsive MK3. The BW35 in the MK3 can be readily beefed up to P5B standards or to BW40 standards and also utilize a later valve body for more responsive changes. The BW box can be easily upgraded.
I realize John sold the manufacturing rights to his "overdrive conversion kit" but I imagine that the company that bought the manufacturing rights to his kit is still in business.
This the way I would go with a factory standard MK3. The MK 2 is a different prospect as it has the DG automatic fitted to it.
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