Overdrive unit for 80 series landcruiser

Submitted: Tuesday, May 25, 2004 at 01:37

ThreadID: 13134 Views:20860 Replies:7 FollowUps:1

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wet feet

Can anyone help with a overdrive unit to reduce revs on a 5 spd manual 1 HDT turbo diesel in a 80 Series landcruiser. 5th gear ratio is 0.88, running a 4.11 final drive which relates to 2800rpm at 110km/h I would like to reduce it to 2100 - 2200rpm.
A 3.54 final drive f +r diff is available ($1700), as is a gearmaster unit from Marks 4wd Adaptors($$$$$$$). Any help would be great. Can the 5th gear be substituted with a lower ratio?

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Reply By: rolande- Tuesday, May 25, 2004 at 08:10

Reply By: Member - Pesty (SA) - Tuesday, May 25, 2004 at 08:39

Reply By: Bob Y. - Qld - Tuesday, May 25, 2004 at 10:44

Reply By: floyd - Tuesday, May 25, 2004 at 14:33

Reply By: Member - DOZER- Tuesday, May 25, 2004 at 15:54

Reply By: bob - Tuesday, May 25, 2004 at 22:05

Reply By: ross - Tuesday, May 25, 2004 at 22:10

Tuesday, May 25, 2004 at 22:10

Wet feet,I agree with the others ,"the rubber overdrive" is the most effective.
Keeps your mechanicals nice and stock for reliability and is the most economical.
My 73 series with .845 5th gear 4.11 diff and 33 in BFG at 110klmh sits on about 2300-2400 rpm.
It throws the speedo out about 6%
It made a huge reduction to cabin noise
I still take off in 2nd gear unless its a really steep hill.
Ive never found 1st gear low range too high with the 33 in tyres and 3F motor,so your turbo diesel will lap it up.
Some of those overdrives are noisy and get hot.

AnswerID: 60169

Follow Up By: wet feet - Tuesday, Jun 01, 2004 at 12:21

Tuesday, Jun 01, 2004 at 12:21

Hi guys,
Thanks a lot to all those that responded. In particular, Dozer, Floyd, Bob Y Ross and Bob. This is the first (well second now)time on explore OZ and I really appreciated the feedback. I have the update model which has the 265/75 x 16 BFG A/T currently and for some funny reason the final drive on the 1HDT is 0.88 cf to 0.81 for say the 1HZ according to my manual (Max Ellery pub'). The "low" final drive makes 200rpm difference at 100kmh.
The reason behind looking for a o/d unit, is in looking for the vehicle, numerous others were looked at and they all seemed to suffer from copious amounts of blowby which I put down to too high revs typically at touring speeds, especially for the turbo diesel. I really appreciated the comments re BHP and torque cf to revs and I will probably go the rubber option as i too were concerned about reliability issues of the o/d unit on the proven toyota product (which incidentally is only supposed to be used at speeds of 80kmh and above in 4 or 5th.
I spoke to my diesel mechanic about high revving diesels and even though the 1hdt is an overhead cam he still thought that 2800rpm on the Hume was too high for the 4.2 litre. Maybe 3litre turbo diesels need more revs, but all the auto's sit on about 2100 - 2300 with a torque convertor though.

Toyota's unofficial comment is the high revs for 5th is that it is made as a 4wd for low ratio and must be useable there????

Anyway thanks a lot for all your comments.

wet feet

FollowupID: 322736