UN.. Gearboxes
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Thread: UN.. Gearboxes

  1. #1
    Tadpole slax's Avatar
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    Default UN.. Gearboxes

    Have done a bit of research and found many older postings on UN1 gearboxes and NG3 gearboxes.

    Have worked out that UN1 gearboxes appearstronger and better suited to higher load/torque situations than NG3 but also appear but be rarer than the proverbial hens tooth.

    Investigations else where have come up with other UN numbers such as UN5 in a renault master van, can anyone entitlighten me as to whether the UN1 box has a newer stronger replacement and what vehicles if any it can be found in.

    Also is there any web source for gear ratios etc that anyone knows of.

    I currently have an old 4 speed UN1 attached to a rover V8, I did not do the join but am curious to know why the box needed to be turned upside down and presumably the diff switched over. Any details would be helpful.

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  2. #2
    1000+ Posts Europa's Avatar
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    Quote Originally Posted by slax
    Have done a bit of research and found many older postings on UN1 gearboxes and NG3 gearboxes.

    Have worked out that UN1 gearboxes appearstronger and better suited to higher load/torque situations than NG3 but also appear but be rarer than the proverbial hens tooth.

    Investigations else where have come up with other UN numbers such as UN5 in a renault master van, can anyone entitlighten me as to whether the UN1 box has a newer stronger replacement and what vehicles if any it can be found in.

    Also is there any web source for gear ratios etc that anyone knows of.

    I currently have an old 4 speed UN1 attached to a rover V8, I did not do the join but am curious to know why the box needed to be turned upside down and presumably the diff switched over. Any details would be helpful.
    UN boxes are the strongest longitudinal transaxle made by Renault, as you say they can be found in the vans, as well as R25 V6 models (non sold here with manual transmission unfortunately). Some R25 4 cylinder models have UN boxes as well.

    They were also used in the Lotus Esprit.

    AFAIK, there are no new longitudinal transmissions like the UN1.

    I would say the box has been rotated in your application precisely for the reason you state - it will have the effect of rotating the dif. Ironically it should theoretically be possibly to rotate the dif internally on a UN1 as the pinion is aligned centrally to the crown wheel.
    '05 Pearl Black Mégane 5-Door LXR(Daily Driver), '75 Trak Yellow R16TSA (Parts Car), '74 Midnight Blue R17TS (Rebuilding), '73 457 Blue R17TL (Parts Car), '72 Alpine White R16TL (Retired), '69 Sunburst Brown R16TS (Awaiting Rebuild), '68 "Appliance White" Europa (Stored)

  3. #3
    Simon's Avatar
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    I ripped the following gearbox details from a website ages ago. I thought it may be useful, suddenly it has become useful. Unfortunately it is in an Excel file format so it doesn't translate well. Car model number at top, then gearbox index number followed by the ratios.

    The type 369 gearbox is the predecessor to the UN1 box, and many of the parts are interchangeable. In Australia the late model Renault 20TS is fitted with a five speed 369 gearbox, and the early leaded petrol Renault 25GTX is fitted with a UN1 gearbox.


    Renault five speed manual transaxle gear and differential ratios

    Model
    Part No.
    1st
    2nd
    3rd
    4th
    5th
    Rev
    Diff

    20
    369.00
    3.36
    2.06
    1.38
    1.06
    0.82
    3.55
    4.11


    369.05
    3.36
    2.06
    1.38
    1.06
    0.82
    3.55
    4.11

    20TX
    369
    3.36
    2.06
    1.38
    1.06
    0.87
    3.55
    3.778

    20LS/TS
    369
    3.82
    2.18
    1.41
    1.03
    0.86
    3.55
    3.778

    21Turbo
    UN1-013
    3.36
    2.05
    1.38
    1.03
    0.82
    3.54
    3.44

    25GTX
    UN 1-03
    3.36
    2.05
    1.38
    1.04
    0.82
    3.55
    3.89

    25V6
    UN 1-04
    3.36
    2.05
    1.38
    0.96
    0.76
    3.55
    3.89

    Alpine GTA
    UN1-05
    3.36
    2.05
    1.38
    1.04
    0.82
    3.55
    3.44

    25 Blindee
    UN 1-06
    3.36
    2.05
    1.38
    0.96
    0.76
    3.55
    4.11

    Alpine Turbo
    UN1-07
    3.36
    2.05
    1.38
    0.96
    0.76
    3.55
    3.44

    25V6 Turbo
    UN1-08
    3.36
    2.05
    1.38
    0.96
    0.76
    3.55
    3.778

    30TX
    369-01/06/017
    3.36
    2.05
    1.38
    1.06
    0.82
    3.55
    3.89

    30TS
    369-01/06/014
    3.36
    2.05
    1.38
    1.06
    0.82
    3.55
    3.89

    Also this site has some nice pics.
    http://www.lotusespritworld.co.uk/ET...l/Gearbox.html

    This place also seems to know Renault gearboxes too.
    http://www.albinsgear.com.au/

  4. #4
    farmerdave
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    Quote Originally Posted by slax
    I currently have an old 4 speed UN1 attached to a rover V8, I did not do the join but am curious to know why the box needed to be turned upside down and presumably the diff switched over. Any details would be helpful.
    The 4 speed "UN type" box is designated as a 367 and was fitted to some R20s and one of the R30 models. The basic ratios are 3.36, 2.06, 1.32, 0.93, reverse 3.18, 9X35 or 8x33 final drive depending on the model.
    Turning the gearbox upside down is more usual in applications using Porsche gearboxes where the engine is ahead of the box, otherwise 5 reverse gears result. The UN type diff can be flipped in the housing to avoid turning the box as the CW/pinion setup is symmetrical, Renault made both types in various forms.

    Farmerdave

  5. #5
    Tadpole slax's Avatar
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    Would the UN Gearbox found in vans such as a Master be built stronger than the UN1 from say the R25, I think the payload on a van being 3.5T and the expectation a van would be drivenharder than most cars.

    I read somewhere this was described as a UN5 was this meant to be UN1-05 or is UN5 correct.

  6. #6
    1000+ Posts Europa's Avatar
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    According to Renault we have the following

    UN1 (early)
    UN1 (late)
    UN5

    The UN5 has has 4 planet wheels in the differential, which should make it stronger. I think the UN1 fitted to Australian R25 4cyl had 2 planet wheels, but I can't be certain - others will know.

    I believe the strongest variation was made for the Lotus Esprit, but I'm not sure of the gearbox suffix for that version.
    '05 Pearl Black Mégane 5-Door LXR(Daily Driver), '75 Trak Yellow R16TSA (Parts Car), '74 Midnight Blue R17TS (Rebuilding), '73 457 Blue R17TL (Parts Car), '72 Alpine White R16TL (Retired), '69 Sunburst Brown R16TS (Awaiting Rebuild), '68 "Appliance White" Europa (Stored)

  7. #7
    Fellow Frogger!
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    Default Transaxle

    Quote Originally Posted by Europa
    According to Renault we have the following

    UN1 (early)
    UN1 (late)
    UN5

    The UN5 has has 4 planet wheels in the differential, which should make it stronger. I think the UN1 fitted to Australian R25 4cyl had 2 planet wheels, but I can't be certain - others will know.

    I believe the strongest variation was made for the Lotus Esprit, but I'm not sure of the gearbox suffix for that version.
    Last time I was looking inside one of these it appeared that the crownwheel if placed on the "other" side of the pinion should be fine BUT the backside of the front(clutch side) would need a recess machined to give crownwheel clearance. As we were going to put this on a smallblock chev the answer was a totally new lump of alli machined to give the bolt pattern on the flywheel side and recess for the crownwheel on the other.

  8. #8
    1000+ Posts alan moore's Avatar
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    The diff ratio in the UN5 would only be good for hill climbing or an off road buggy. It is way too low and is something like a 5 to 1 ratio.
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  9. #9
    Tadpole slax's Avatar
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    Quote Originally Posted by alan moore
    The diff ratio in the UN5 would only be good for hill climbing or an off road buggy. It is way too low and is something like a 5 to 1 ratio.
    Does anyone have the ratios for a UN5 box ?

    PS thanks to all so far you have all been a wealth of information and exceptionally quick.

  10. #10
    1000+ Posts Europa's Avatar
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    Quote Originally Posted by slax
    Does anyone have the ratios for a UN5 box ?

    PS thanks to all so far you have all been a wealth of information and exceptionally quick.
    Head over to http://www.8gordini.com and download the M.R.BVUN manual.
    '05 Pearl Black Mégane 5-Door LXR(Daily Driver), '75 Trak Yellow R16TSA (Parts Car), '74 Midnight Blue R17TS (Rebuilding), '73 457 Blue R17TL (Parts Car), '72 Alpine White R16TL (Retired), '69 Sunburst Brown R16TS (Awaiting Rebuild), '68 "Appliance White" Europa (Stored)

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