Diff's and gearboxes mated to 18RG's.

[RT104GT]

having been an owner of an original 18RG engine (serial number 095125) mated to a P51 GT gearbox and a 7.1 inch 4.111;1 limited slip differential. I would like to hear from people about what drive chains their Celicas RAN and now Run, and why you all lust after a P51 and f series Diff.
.............................editted.............. ......
a few 18RG's came into Springvale Melbourne and by 1984 Modern Motor was full of second hand 18RG's mated to W50 GT gearboxes.
I would like to hear from anyone who has a genuine P51 box and what they think.
I would like to hear from anyone who bought an 18RG in the 1980's and what car you put it into?
I would like to hear from anyone with a genuine F series 7.5 diff 4.111 or 4.3 and where it came from?
For my money the Supra box is the ideal replacment for the P51 in the form of a W55 is an ideal replacement.
What does the forum think?

[WDE_BDY]

The F series is 7.5"

And I agree the W55 is the better box option, even the factory went to that in the RA63. The RA63 drivetrain I have is now in a KE70 ute though and is jap spec as I'm in NZ.

Callum

[RT104GT]

Hi callum.
Whats the chance of finding any wrecked RT104 or RT112 GT SR etc in New Zealand wreckers? I need the dash and instruments, and trim, the 2.5 inch small clock from the GT. I understand there are a few wrecked coupes over your way?
And the obvious question any LSD's around anywhere and P51 or W55 gearboxes?

I understand that you can use gearboxes and diffs for Celica/Corona out of certain commercial two wheel drive Toyota utes?

[WDE_BDY]

Well I just bought an F series Torsen centre from an Altezza for the Crown diff going into my KE70, unfortunately though haven't seen any RT104's or RT112's in my area so can't help you there. There are plenty of W55 boxes around, its the bellhousing that is hard to find.

Callum

[The Witzl]

I've never used a P51 gearbox behind any of my 18R-Gs, but I have used a W50 and a W58. Currently I run the W58 box behind my hybrid 18R-GE and find that it's a billion times better than the W50 box in both gear ratios, strength, ease of shifts, and noise.
Admittedly my W50 was probably a bit worn, but still the W58 is so much better.

To fit the W55/W57/W58, you need to get your hands on a 21R/22R bellhousing and clutch fork that was mated to the W55 gearbox in either an RA60, RA65 or RT142. You will also need the clutch slave cylinder that matches, but the RA2* slave can be used with a little modification.

You can use the RA65 gearbox mount or the RA23/28 gearbox mount, but i used the RA65 as it's much meatier and stronger than the RA28 item (i bought the Kelpro brand). Using the RA65 mount and stock RA28 gearbox crossmember, the crossmember's front bolt holes only lined up with the rear bolt holes in the floorpan of the car..... simple fix invoved some 8mm steel plate unto which the gbox crossmember bolts to which also bolts to the floorpan's stock bolt holes.

The other area of question with using the W55/57/58 is the selector position. To fit the box without cutting up your floorpan you need to use the RT142 selector housing, which is the most forward available (see the numerous threads on this topic here in the forums). This does put the stick pretty far forward, and in 1st/3rd/5th gear the stick is pretty close to the dash console..... but a little heat and some bending of the stick would sort this out

Everything else mates up perfectly - tailshaft, clutch, speedo cable (RT142 speedo driver gear is correct 4.11:1 ratio i think) etc all just go on as per normal.


The biggest difference i've noticed with the move from W50 -> W58 is the gear ratios. 5th gear is actually a REAL overdrive gear.... 80kph is just over 2000rpm in 5th, which does wonders for your economy and the EFI 18R-GE has so much torque down low it just loves the new 5th gear. Normal city driving is also easier thanks to not having to shift gears so much when booting it a little, the gears have some decent reach now.

The last point is the strength. We ALL know the W58 is well superior in strength, and being that I'm going turbo in the not too distant future this was very important to me!

[RT104GT]

Thanks for all the feedback, you sure know your stuff. OK about there being a DOHC marked cover for the 18RG.
I am going to email the japanese owner, to find out the good oil.

[WDE_BDY]

OK about there being a DOHC marked cover for the 18RG.
I am going to email the japanese owner, to find out the good oil.

Like this?

[river]

Hi,

While the W58 offers a lower 5th gear for better cruising (over the W50), it has a longer 2nd gear. For cruising the W58 is nicer than the W50 - for acceleration the W50 is better.

However, if you have a P51 then you got the best that Toyota made at that time. All the first gen GT/GTV 18R-G powered Celicas got the P51, and so did the 18R-G powered GT Coronas and I think even some of the 2-door "sporty" Crowns got them.

The P51 is ostensibly a Porsche/ZF patented gearbox that was built by Toyota, and as such it used specialised bands for synchronisation instead of the normal type of synchros. They're a very strong steel-case box.

The W50 was used behind the standard 18R engines, while the P51 was used behind the 18R-G engines. The P51 was phased out in the late 70s and I think (though yet to be confirmed) that all 18R/18R-G powered vehicles in the Celica range used the W50 with the introduction of the RA40. I am not sure if this was a production cost issue (ie P51 costing more to produce and maybe license costs due to the Porsche/ZF patent), or by this stage the 18R-GU/18R-GUE had lost enough HP (over the 18R-G/18R-GR) that the W50 was deemed strong enough to sit behind it.

The P51 is very notchy on the gear changes, very quiet (considering it's age) and geared perfectly for the 18R-G. You can hit the redline in all gears except for 5th gear, where the gearing limits the engine to 5600rpm. Sometimes, when stationery, reverse is hard to select - however if you put it in 1st gear (clutch in of course) then it will slip into reverse. This is a characteristic of this box and some other Toyota boxes.

In any event, P51's are very rare and getting parts is nigh impossible to get, therefore you'll need parts custom made for them. My P51 is a little worn on the synchro for 3rd gear (on the down change) and finally, after 5 years, I was able to get a spare box. I've yet to get this box overhauled 'cos it will need a gearbox artisan and I'm sure it's going to cost me dearly - but this is par for the course when you restore some of these old rare cars.

F-series 2-pinion LSD.... what more can be said except it's a tough LSD that can take whatever your 18R-G is going to give it. Still used and recommended by many Toyota enthusiasts. The 1st gen GT Celicas used a 3.909 ratio. Like the P51, if your classic has one then keep it.

seeyuzz
river

[Vios-GT_07]

Sometimes, when stationery, reverse is hard to select - however if you put it in 1st gear (clutch in of course) then it will slip into reverse. This is a characteristic of this box and some other Toyota boxes.

i'd just play around with it i.e. third, fourth, then reverse... good wrist exercise and reverse will seem really smooth after that.. most manuals don't like reverse..

edit : i had a ride in an 18R-G celica the other night.. finally the first ride ever, and yeh it was good.. i can't believe it still has original internals, afaik a bit weak i reckon from what i gather in comparison with the hype here.. but none the less i can see why it's the tractor motor.. i should've asked what box he was running with but i remember 5th was very close to 4th... i'd prefer this ratios though coz it seemed to suit.. 2nd and 3rd had a good kick to it..

[RT104GT]

However, if you have a P51 then you got the best that Toyota made at that time. All the first gen GT/GTV 18R-G powered Celicas got the P51, and so did the 18R-G powered GT Coronas and I think even some of the 2-door "sporty" Crowns got them.

Mine failed at less than 100,000 heavy km in the middle of the 79 Repco Rally.


The P51 is very notchy on the gear changes, very quiet (considering it's age) and geared perfectly for the 18R-G. You can hit the redline in all gears except for 5th gear, where the gearing limits the engine to 5600rpm. Sometimes, when stationery, reverse is hard to select - however if you put it in 1st gear (clutch in of course) then it will slip into reverse. This is a characteristic of this box and some other Toyota boxes.


DITTO W51.


In any event, P51's are very rare and getting parts is nigh impossible to get, therefore you'll need parts custom made for them. My P51 is a little worn on the synchro for 3rd gear (on the down change) and finally, after 5 years, I was able to get a spare box. I've yet to get this box overhauled 'cos it will need a gearbox artisan and I'm sure it's going to cost me dearly - but this is par for the course when you restore some of these old rare cars.

Toyota could not fix my P51 in 1979 as parts were unobtainable after Toyota discontinued the licence building in 1978.

I cant imagine where you would find parts these days.
The main problem was large bearings.

My P51 is still somewhere in Hamilton in a thousand pieces.
The guy who borrowed it has dementure and forgot where all the parts are located.


F-series 2-pinion LSD.... what more can be said except it's a tough LSD that can take whatever your 18R-G is going to give it. Still used and recommended by many Toyota enthusiasts. The 1st gen GT Celicas used a 3.909 ratio. Like the P51, if your classic has one then keep it.

Corona used rare 4.111: Crown wheel and pinion unavailable in Australia.

RT104GT

[RT104GT]

Actually reflecting on Rivers comments I d not know which gearbox I have but it behaves exactly the same as the p51 pulled out. it is notchy it crunches from 4th to 3rd and crunches from 3rd to second and you can beat the syncros.

Toyota say to run Dextron 3 and not to run normal Gearbox oil.

If anyone can assist with the gearbox casting numbers for both boxes, I will put it on this site when I read it off the box.

I counted three or four 5 speed Toyota boxes for sale quite cheaply on Ebay a couple mated to Holden bell housings for about $100 each and a couple of others for about $200

[river]

Hi,

You could have a W50. The ratios are fairly close to the P51 and it uses the same outside casing - which means it bolts right into the car the same as a P51.

seeyuzz
river

[RT104GT]

Hi

33111-20090 just read off casing.

Dozens of 5 speed variants in parts book depending on diff used.

5F has dual retaining reverse idler retainers.


09/1975 5F 3.909 33030-20150 P51 SR/Celica GT

09/1975 5F 4.100 33030-20200 P51GT Corona

08/1973 5F 33101-20010 W50 GL

33111-20090 W50 late Celica W50 Steel

Diffs in Corona are 6.7 and LSD is 7.1 inches
F Celica 7.5?

[The Witzl]

River - remember my arguments regarding the gearbox casings of the W50 vs the P51??

the P51 appears to not have the "ridgeback" like the W50 - the top of the casing rises as it goes forward towards the bellhousing

River.... let me underneath your car and I will prove it. Dont worry, i wont touch anything!

[RT104GT]

No one gets under my skirts.


NOW I WANT YOU ALL TO GO SHINE A TORCH ON YOUR TRANSMISSION HOUSINGS THANKS


gearbox

on ebay is 33111-20090

NOPE a P51 $140.00



Dont bid Im getting it cheap as.

\I am also winning the timing stuff so go away please.