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UN1 Holloway reinforced shaft/gears kit available again - group buy - Gearchange/Gearbox/Clutch - The Lotus Forums Jump to content
MrDangerUS

UN1 Holloway reinforced shaft/gears kit available again - group buy

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Yep, need Ten Little Indians to play!

Well..., actually only 6 now, LOL.

I met in November 2014 with the President of EMCO Gears, which manufactured the UN-1 transmission upgrade kit for Holloway Performance. EMCO is willing to make more kits, but the minimum production order would have to be at least 10 units. EMCO is asking $4000.00 per kit, which is very close to the closing sale price of the original Holloway kit. This is a great deal, because the original production run required 20 units minimum.

EMCO manufactures racing gear sets for INDY cars, Porsche, Ferrari and other high performance cars, so they have a proven track record.

It would be great if we could find 10 people interested in acquiring this kit and be able to organize some kind of "group buy". IF we identify 10 people interested in this kit, I will then be in position to discuss the arrangements with EMCO and work out the details.
Here are details from Craig, the owner of Holloway Performance and the design reasons:

"Lotus did very little to upgrade the gearbox after the S4 model in 1991. The introduction of the V8 in 1997 placed a new amount of stress on the design, which is why the upgrade kit was developed. The only change in 1998 was the position of the external gear shift "translator" on the outside of the gearbox case. Nothing on the internals changed.

The upgrade kit addresses 3 weaknesses.
1. The primary shaft which takes the power from the engine is a 1 piece design on the upgrade, versus 2 pieces on the OEM. All flex is removed.
2. The primary shaft is larger diameter and 9310 grade race steel, which eliminates the potential for shaft breaking on the 5th gear overhang (a common failure on OEM).
3. All bearings have higher torque specs, plus gears 1 and 2 ratios are optimized to reduce the "step" between gears, allowing for better synchronizer functionality.

All of these changes make the gearbox internals well capable of 600+ ft lb of torque. Great insurance as a new gearbox would be almost impossible to locate should the OEM fail.

Please be aware that the EMCO / Holloway Performance kit is designed as drop in kit for gearboxes with 52mm rear shaft bearing. 52 mm bearing was used starting with the S4 model.
I took the 52mm rear shaft bearing statement from Holloway page. I do not have transmission parts list for SE model, therefore I can not compare to S4 and V-8 units and verify if it is only larger outside diameter bearing difference or if the primary shaft was different also. If it is larger outside diameter bearing, then trans case could be machined to fit a new 52 mm bearing... S4 primary shaft is A082F6545S (UN26)

I am just trying to see if we can find 6 more people interested. I am buying one of 10 and there are 3 people who showed the interest on LotusTalk in making their transmissions much stronger and eliminating known issues.

 

 

Holloway UN1 upgrade kit.jpg

Edited by MrDangerUS

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This kit fits only:
UN1 – 026 – High Torque G/Box – Stronger Casings etc. introduced circa 1993. This 'Box had rear cover with R/H shift lever
UN1 – 027 – V8 Gearbox – Introduced in 1996 on V8 Esprit. Similar to 4 Cyl High Torque units with new Clutch
Housing. It carried over the R/H shift lever.

This kit will fit only S4, S4S and V-8 Esprits.

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Holloway kit decreased first gear ratio focusing on addressing synchronization engagement issue.  It did not drop the first gear ratio as extremely as Quaife/GTO kit. This makes Holloway kit more friendly for lower torque 4 cylinder engines. 

1-st    3.0   (GTO 2.66)

2-nd  1.94 (GTO  1.75)

 

 

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1 hour ago, plumdeplakmuis said:

Just to be sure, 1998 GT3 will not fit?

It WILL fit, if you have one of these in your car: 

UN1 – 026 – High Torque G/Box – Stronger Casings etc. introduced circa 1993. This 'Box had rear cover with R/H shift lever
UN1 – 027 – V8 Gearbox – Introduced in 1996 on V8 Esprit. Similar to 4 Cyl High Torque units with new Clutch

I have a feeling that you have one of the above "hi torque" gearboxes. If you're not sure, please ask the nearest dealer. If you give them your VIN, they will be able to tell you.

Edited by MrDangerUS

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5 hours ago, plumdeplakmuis said:

Just to be sure, 1998 GT3 will not fit?

Jaap,
het zal passen, als uw auto deze 026 of 027 hoge koppel versnellingsbak geïntroduceerd circa 1993 heeft.

ik denk dat uw auto een van heeft de 'Hallo koppel' versnellingsbakken. Als u niet zeker weet, vraagt u de dichtstbijzijnde dealer. Als je ze uw VIN geven, zullen ze u kunnen vertellen.

Best Regards

John

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Dear John,

(You speak Dutch?)

Gearbox is a UN 28 for the GT3. Do you know differences in the shaft cause the upgrade not to fit?

If it is the crownwheel, I'm considering also changing the diff to Quaife LSD, and then installing a new wheel.


VAN DER LEE Turbo Systems     -      www.vdlee.com

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All the UN1 Lotus Gearboxes are very similar. This is the 'simplified' history.
These changes included Revised Gearchange & Synchro on Reverse Gear. The introduction of the Esprit GT3 created another variant of the UN1 gearbox. This variant is only approved for the 2 Litre version of the Lotus Turbocharged engine. This version of the UN1 is designated UN1 – 028 and has a different Crownwheel & Pinion that is only suitable for use and validated for the GT3 engine. UN1- 028 is not recommended for use on the 2.2 Litre Engine.
UN1 – 016 – 4 Cylinder G/Box – First variant of Lotus UN1– First used on X180 Introduction in 1988. This 'Box had rear cover with L/H shift lever.
UN1 – 026 – High Torque G/Box – Stronger Casings etc. introduced circa 1993. This 'Box had rear cover with R/H shift lever
UN1 – 027 – V8 Gearbox – Introduced in 1996 on V8 Esprit. This box was basically similar to 4 Cyl High Torque units with new Clutch
Housing. It carried over the R/H shift lever. It had synchro on Reverse Gear and a higher 5th gear. The shift mechanism was changed to an improved version of the R/H mechanism from VIN W2272 – this requires a different shift master unit and cables.

UN1 – 028 – 4 cylinder G/Box for the Esprit GT3 (2.0 Litre) w/different Axle &Gear Ratios - not suitable for 2.2 Litre Engine Torque.
In a nutshell the 026 & 027 Gearboxes are very similar except for the Clutch Housing, Synchro on Reverse, 5th Gear Ratio. The clutch Housings & Rear Cover (with shift lever) can be changed over easily. Minor improvements were introduced at the time of Sport 350 to improve durability.
The Lotus versions of the Box were very similar to Renault units at first sight. What people do not realize is that the Lotus versions had some very important differences. The main issue is the crown wheel & pinion. Although the Ratio is identical to some Renault vehicle applications the material is different. The Renault material will not survive the Lotus application (even the earliest non intercooled cars). Running on the approved oil is another critical item.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The original UN1 design, although durable and lightweight, was not crafted for the high torque of a Lotus Esprit. The OEM gearbox possesses three weaknesses, all of which are managed by the Holloway Performance upgrade.
The primary shaft is two pieces connected by a weak spline configuration subject to breakage
The 5th gear overhang is tapered and poorly supported, creating a weakness
The primary shaft flexes under high torque due to its narrow diameter, again creating vulnerability
In addition to the weaknesses of the OEM design, the UN1 gearbox is nearing obsolescence. Parts are difficult to obtain and expensive. When it breaks, and it will, the Holloway Performance kit enables you to increase the UN1’s capacity.
Which model of Esprit? Those with 52mm rear shaft bearing, starting with the S4 model
What are the gear ratios? 1st/2nd are 3.00/1.94 (OEM 3.36/2.05)
What are the gear cuts? 1st is straight cut; 2nd is helical cut
Why change the gear ratios? To lower the “step” between gears, easing synchro transition
Is a different clutch plate required? Original clutch is used; no alterations

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Bummed. 1992 SE is looking for improved xmission - what happened to the 6 speed that was around years ago? Was it also improved for torque as well or just 6 gears?

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Mikie,

If you wish, you may start looking for  026 or 027 hi torque tranny on ebay (actually there is one on US ebay, 02 V8 donor), or call  http://www.lotusbits.com/about.html

 

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On 1/19/2016 at 10:24, plumdeplakmuis said:

Dear John,

(You speak Dutch?)

Gearbox is a UN 28 for the GT3. Do you know differences in the shaft cause the upgrade not to fit?

If it is the crownwheel, I'm considering also changing the diff to Quaife LSD, and then installing a new wheel.

Jaap,

 

Please check your car date of production on the plaque. Here is the information from Lotus:

Transmission designation - S4S; GT3 prior June '98  has UN1-026

                                          -GT3  from June '98      has      UN1-028

                                          - V8                                has     UN1-027

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Man this is tempting but I'd be hit with such brutal import duties. It'd be nice to ramp the V8 up to a more respectable 500 HP


Vanya Stanisavljevic '91 Esprit SE | '91 Elan SE | '97 XK8

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On 1/19/2016 at 10:24, plumdeplakmuis said:

Dear John,

(You speak Dutch?)

Gearbox is a UN 28 for the GT3. Do you know differences in the shaft cause the upgrade not to fit?

If it is the crownwheel, I'm considering also changing the diff to Quaife LSD, and then installing a new wheel.

Jaap,

kijken dit diagram:   http://www.deroure.com/diagrams.asp?TBL=1588&MAK=1&MDL=15&SMA=0&SMO=0&ST=&SC=0
het toont de dezelfde achterste as lagers op UN1-028 / GT3. Dit doet me denken dat rekening houdend met diameter hetzelfde is.

Primaire as-nummer is verschillend voor GT3, maar ik weet niet waarom. U kunt de schacht kit toch krijgen. Als u het niet gebruikt, kunt u het later verkopen. U zult nooit verliezen geen geld op dit.
Cheers

John

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May also be interested in one of these conversions depending on when they expected to be made/manufatured.

Been planning to install my 450 BHP chip and or an intercooler for some time now so the upgrade would do nicely

Paul

 

 

 

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I have found some better mail rates.

New Zealand and Australia $79 USD + 55 insurance.

Any other country, which is closer to US will be less.

Russia shipping - $100

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On 1/22/2016 at 05:40, Vanya said:

Man this is tempting but I'd be hit with such brutal import duties. It'd be nice to ramp the V8 up to a more respectable 500 HP

Vanya,

 

What are the value to duty fees rates? I'm sure something can be worked out. It takes TWO  to TANGO!

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I believe all in all I pay 30% on top of the value + shipping together, taxes and import fees together...


Vanya Stanisavljevic '91 Esprit SE | '91 Elan SE | '97 XK8

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The cost of the kit is 4K and not 10K. Majority of Lotus Owners are a good mechanics and they can manage to DIY the transmission.

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Except that I must buy an S or S4s tranny (apparently $5K+) then try to fit it to my SE (cost unknown) even before applying the modified parts ($4k) it would work on my coach, correct? That is why I asked for information about the 6 speed tranny that someone once made for the Esprit as perhaps a better option...

Edited by MikieP

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