4.7 low ratio RF1A TC to surf autobox

[dannyboy77]

right just thought i would do the write up for getting rid of the stock chain driven TC and putting on a 4.7 low ratio gear driven transfer case onto the back of the surf/lexus A341E auto box. This is easier said than done as there is a lot of confusing infomration about the conversion with NO PICS!!!

the reason for the conversion / mod is that the chain TC VF1A has a low ratio (for offroading) of 2.57:1, the gear TC RF1A is 2.28:1 but you can only increase the low range ratio on the gear TC to 4.7 but NOT you cant mod the chain TC. the RF1A is normally found on the old pick ups and the VF1A on the surfs and the automatic surf which is what i have. this will give you 51% more power / torque at low range

http://www.4wdhub.com/tcase/toyota.html

Transfer Case Setup Transfer Case Ratio FinalDrive Ratio
Stock 2.28:1 44:1
Replacement Gears 4.70:1 91:1

as you can see the final ratio as twice the stock ratio!

so the build, as usual not straight forward and a bit of a pig. i was in contact with lowrange offroad which were helpful but after speaking to them discussing what i had and sending pics and waiting weeks for it to turn up i ended up with the wrong adaptor! so i had to send it back and get then get them to send the right one.

the problem with changing from chain to gear TC is the chain TC (right) is a female end and the gear TC (left) is a male end plus the bolt configuration to go on the adaptor (the collar piece between the autobox and the TC) is different. you can see the photo below

https://flic.kr/p/JcYh5G

so to get it to fit to the male end of the autobox and to marry to the existing adaptor which goes between the auto box and TC you also need an adaptor plate that fits onto the new gear TC and an female to female 23 spine coupler to marry to the autobox male outputshaft

https://flic.kr/p/JvR5NF

you can see the adaptor for the gear TC will fit on the existing extension piece that goes between the autobox and the TC

https://flic.kr/p/JCGjUX

the existing adaptor collar that goes between the autobox and TC has a rubber seal and a bearing in the middle of it that needs to be removed as the diameter of the female to female sleeve that attaches the male end of the TC to the male end of the autobox is bigger than the internal diameter of the bearing. Lowrange said it isn’t needed, Toyota have put it there i gather to eliminate the rotary motion but one didn’t come with the kit so will see if there is any vibration?

https://flic.kr/p/JCGbrK

https://flic.kr/p/JvR4BH

now you can see i have removed the bearing and the rubber seal etc

https://flic.kr/p/JcYj2N

you get a piece of tube that fits in the middle of the adaptor which has a rubber seal that will fit tight to the output shaft of the new gear TC

https://flic.kr/p/HGwCZs

so fitting it together you can see through the top of the adaptor collar how it all fits together

https://flic.kr/p/JcYhCq

https://flic.kr/p/JcYinw

https://flic.kr/p/JcYinw

just checking to make sure it all fits

https://flic.kr/p/JcYftf

[dannyboy77]

just to go off at a slight tangent here. I have gone for the 4.7 low ratio TC but you can get a crawler box which would fit between the TC and the existing adaptor collar. The crawler box duel set up has a low ratio of 2.28 and the exiting low ratio of TC is 2.28 so combined would equal 4.7.



https://www.marlincrawler.com/transf...-transfer-case

there are pros and cons for this. I have gone for the straight 4.7 low ratio as with the duel set up i would have to lengthen the front prop and shorten the rear prop and move the cross member underneath. Also i think i have to go top shift rather than forward shift because i think i cant have the 4” forward shift as i don’t think it would work with the opening of the top of the existing adaptor collar. Also you can see the bolt configuration of the gear TC for the top shift lever is different to the bolt configuration of the existing adaptor so i couldn’t use a lever designed for the gear TC. And i don’t think the existing the lever in the surf would work or not on the forward shift gear TC? For someone else to figure out. The existing surf TC is forward shift btw.

https://www.marlincrawler.com/tech/t...fer-case-bible

st to finish off the write up. with the TC being a top shift i had to cut another hole for the lever to come through the body. from the pics below you can see i might be able to of fitted a forward shift TC and use the existing shifter but i have opted for the top shift to be safe.

https://flic.kr/p/JpmYRm


i will blank off the existing opening (right) and the shifter will go on the left

https://flic.kr/p/HTMxGB

i had to make a metal bracket to bolt down the waterproof gaiter for the new shifter and fit it to the existing waterroof gaiter of the automatic gear shifter.

https://flic.kr/p/HTPmAq

just to side track the speedo sensor from the chain TC (right) is different from the speedo sensor in the new chain TC (left). also the chain TC sensor works mechanically not electrically. you need a mech to elec convetor that fits onto the 3 pin conncector.

https://flic.kr/p/J1BeFV

https://flic.kr/p/J1Bi1F

all fitted now and looks quite neat. need to get a leather gaiter just to finish it off

https://flic.kr/p/JA6jRG

[dannyboy77]

for some reason flickr pics wont show up in the tread? dont know why

[galooph]

Here you go, dannyboy, I sorted out the inline pics

right just thought i would do the write up for getting rid of the stock chain driven TC and putting on a 4.7 low ratio gear driven transfer case onto the back of the surf/lexus A341E auto box. This is easier said than done as there is a lot of confusing infomration about the conversion with NO PICS!!!

the reason for the conversion / mod is that the chain TC VF1A has a low ratio (for offroading) of 2.57:1, the gear TC RF1A is 2.28:1 but you can only increase the low range ratio on the gear TC to 4.7 but NOT you cant mod the chain TC. the RF1A is normally found on the old pick ups and the VF1A on the surfs and the automatic surf which is what i have. this will give you 51% more power / torque at low range

http://www.4wdhub.com/tcase/toyota.html

Transfer Case Setup Transfer Case Ratio FinalDrive Ratio
Stock 2.28:1 44:1
Replacement Gears 4.70:1 91:1

as you can see the final ratio as twice the stock ratio!

so the build, as usual not straight forward and a bit of a pig. i was in contact with lowrange offroad which were helpful but after speaking to them discussing what i had and sending pics and waiting weeks for it to turn up i ended up with the wrong adaptor! so i had to send it back and get then get them to send the right one.

the problem with changing from chain to gear TC is the chain TC (right) is a female end and the gear TC (left) is a male end plus the bolt configuration to go on the adaptor (the collar piece between the autobox and the TC) is different. you can see the photo below



so to get it to fit to the male end of the autobox and to marry to the existing adaptor which goes between the auto box and TC you also need an adaptor plate that fits onto the new gear TC and an female to female 23 spine coupler to marry to the autobox male outputshaft



you can see the adaptor for the gear TC will fit on the existing extension piece that goes between the autobox and the TC



the existing adaptor collar that goes between the autobox and TC has a rubber seal and a bearing in the middle of it that needs to be removed as the diameter of the female to female sleeve that attaches the male end of the TC to the male end of the autobox is bigger than the internal diameter of the bearing. Lowrange said it isn’t needed, Toyota have put it there i gather to eliminate the rotary motion but one didn’t come with the kit so will see if there is any vibration?





now you can see i have removed the bearing and the rubber seal etc



you get a piece of tube that fits in the middle of the adaptor which has a rubber seal that will fit tight to the output shaft of the new gear TC



so fitting it together you can see through the top of the adaptor collar how it all fits together





just checking to make sure it all fits

[galooph]

Part 2...

just to go off at a slight tangent here. I have gone for the 4.7 low ratio TC but you can get a crawler box which would fit between the TC and the existing adaptor collar. The crawler box duel set up has a low ratio of 2.28 and the exiting low ratio of TC is 2.28 so combined would equal 4.7.

https://www.marlincrawler.com/transf...-transfer-case

there are pros and cons for this. I have gone for the straight 4.7 low ratio as with the duel set up i would have to lengthen the front prop and shorten the rear prop and move the cross member underneath. Also i think i have to go top shift rather than forward shift because i think i cant have the 4” forward shift as i don’t think it would work with the opening of the top of the existing adaptor collar. Also you can see the bolt configuration of the gear TC for the top shift lever is different to the bolt configuration of the existing adaptor so i couldn’t use a lever designed for the gear TC. And i don’t think the existing the lever in the surf would work or not on the forward shift gear TC? For someone else to figure out. The existing surf TC is forward shift btw.

https://www.marlincrawler.com/tech/t...fer-case-bible

st to finish off the write up. with the TC being a top shift i had to cut another hole for the lever to come through the body. from the pics below you can see i might be able to of fitted a forward shift TC and use the existing shifter but i have opted for the top shift to be safe.



i will blank off the existing opening (right) and the shifter will go on the left



i had to make a metal bracket to bolt down the waterproof gaiter for the new shifter and fit it to the existing waterroof gaiter of the automatic gear shifter.



just to side track the speedo sensor from the chain TC (right) is different from the speedo sensor in the new chain TC (left). also the chain TC sensor works mechanically not electrically. you need a mech to elec convetor that fits onto the 3 pin conncector.





all fitted now and looks quite neat. need to get a leather gaiter just to finish it off

[dannyboy77]

thanks for that galooph